Auto merge of #3727 - RalfJung:rustup, r=RalfJung

Rustup

To unblock https://github.com/rust-lang/miri/pull/3688

175 files changed, 3016 insertions, 2108 deletions

diff --git a/compiler/rustc_ast_lowering/src/expr.rs b/compiler/rustc_ast_lowering/src/expr.rs
index 624bca525b9..218fa974022 100644
--- a/compiler/rustc_ast_lowering/src/expr.rs
+++ b/compiler/rustc_ast_lowering/src/expr.rs
@@ -103,7 +103,6 @@ impl<'hir> LoweringContext<'_, 'hir> {
                         ParamMode::Optional,
                         ParenthesizedGenericArgs::Err,
                         ImplTraitContext::Disallowed(ImplTraitPosition::Path),
-                        None,
                         // Method calls can't have bound modifiers
                         None,
                     ));
diff --git a/compiler/rustc_ast_lowering/src/item.rs b/compiler/rustc_ast_lowering/src/item.rs
index 74e04eff4f3..d59ac576629 100644
--- a/compiler/rustc_ast_lowering/src/item.rs
+++ b/compiler/rustc_ast_lowering/src/item.rs
@@ -56,7 +56,7 @@ impl<'a, 'hir> ItemLowerer<'a, 'hir> {
         owner: NodeId,
         f: impl FnOnce(&mut LoweringContext<'_, 'hir>) -> hir::OwnerNode<'hir>,
     ) {
-        let mut lctx = LoweringContext::new(self.tcx, self.resolver);
+        let mut lctx = LoweringContext::new(self.tcx, self.resolver, self.ast_index);
         lctx.with_hir_id_owner(owner, |lctx| f(lctx));
 
         for (def_id, info) in lctx.children {
@@ -190,6 +190,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 let (generics, (ty, body_id)) = self.lower_generics(
                     generics,
                     Const::No,
+                    false,
                     id,
                     ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
                     |this| {
@@ -221,7 +222,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
 
                     let itctx = ImplTraitContext::Universal;
                     let (generics, decl) =
-                        this.lower_generics(generics, header.constness, id, itctx, |this| {
+                        this.lower_generics(generics, header.constness, false, id, itctx, |this| {
                             this.lower_fn_decl(
                                 decl,
                                 id,
@@ -265,6 +266,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 let (generics, ty) = self.lower_generics(
                     &generics,
                     Const::No,
+                    false,
                     id,
                     ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
                     |this| match ty {
@@ -293,6 +295,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 let (generics, variants) = self.lower_generics(
                     generics,
                     Const::No,
+                    false,
                     id,
                     ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
                     |this| {
@@ -307,6 +310,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 let (generics, struct_def) = self.lower_generics(
                     generics,
                     Const::No,
+                    false,
                     id,
                     ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
                     |this| this.lower_variant_data(hir_id, struct_def),
@@ -317,6 +321,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 let (generics, vdata) = self.lower_generics(
                     generics,
                     Const::No,
+                    false,
                     id,
                     ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
                     |this| this.lower_variant_data(hir_id, vdata),
@@ -348,12 +353,9 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 // parent lifetime.
                 let itctx = ImplTraitContext::Universal;
                 let (generics, (trait_ref, lowered_ty)) =
-                    self.lower_generics(ast_generics, *constness, id, itctx, |this| {
+                    self.lower_generics(ast_generics, Const::No, false, id, itctx, |this| {
                         let modifiers = TraitBoundModifiers {
-                            constness: match *constness {
-                                Const::Yes(span) => BoundConstness::Maybe(span),
-                                Const::No => BoundConstness::Never,
-                            },
+                            constness: BoundConstness::Never,
                             asyncness: BoundAsyncness::Normal,
                             // we don't use this in bound lowering
                             polarity: BoundPolarity::Positive,
@@ -389,6 +391,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     ImplPolarity::Negative(s) => ImplPolarity::Negative(self.lower_span(*s)),
                 };
                 hir::ItemKind::Impl(self.arena.alloc(hir::Impl {
+                    constness: self.lower_constness(*constness),
                     safety: self.lower_safety(*safety, hir::Safety::Safe),
                     polarity,
                     defaultness,
@@ -400,15 +403,10 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 }))
             }
             ItemKind::Trait(box Trait { is_auto, safety, generics, bounds, items }) => {
-                // FIXME(const_trait_impl, effects, fee1-dead) this should be simplified if possible
-                let constness = attrs
-                    .unwrap_or(&[])
-                    .iter()
-                    .find(|x| x.has_name(sym::const_trait))
-                    .map_or(Const::No, |x| Const::Yes(x.span));
                 let (generics, (safety, items, bounds)) = self.lower_generics(
                     generics,
-                    constness,
+                    Const::No,
+                    false,
                     id,
                     ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
                     |this| {
@@ -429,6 +427,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 let (generics, bounds) = self.lower_generics(
                     generics,
                     Const::No,
+                    false,
                     id,
                     ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
                     |this| {
@@ -609,30 +608,45 @@ impl<'hir> LoweringContext<'_, 'hir> {
         // This is used to track which lifetimes have already been defined,
         // and which need to be replicated when lowering an async fn.
 
-        let generics = match parent_hir.node().expect_item().kind {
+        let parent_item = parent_hir.node().expect_item();
+        let constness = match parent_item.kind {
             hir::ItemKind::Impl(impl_) => {
                 self.is_in_trait_impl = impl_.of_trait.is_some();
-                &impl_.generics
+                // N.B. the impl should always lower to methods that have `const host: bool` params if the trait
+                // is const. It doesn't matter whether the `impl` itself is const. Disallowing const fn from
+                // calling non-const impls are done through associated types.
+                if let Some(def_id) = impl_.of_trait.and_then(|tr| tr.trait_def_id()) {
+                    if let Some(local_def) = def_id.as_local() {
+                        match &self.ast_index[local_def] {
+                            AstOwner::Item(ast::Item { attrs, .. }) => attrs
+                                .iter()
+                                .find(|attr| attr.has_name(sym::const_trait))
+                                .map_or(Const::No, |attr| Const::Yes(attr.span)),
+                            _ => Const::No,
+                        }
+                    } else {
+                        self.tcx
+                            .get_attr(def_id, sym::const_trait)
+                            .map_or(Const::No, |attr| Const::Yes(attr.span))
+                    }
+                } else {
+                    Const::No
+                }
             }
-            hir::ItemKind::Trait(_, _, generics, _, _) => generics,
+            hir::ItemKind::Trait(_, _, _, _, _) => parent_hir
+                .attrs
+                .get(parent_item.hir_id().local_id)
+                .iter()
+                .find(|attr| attr.has_name(sym::const_trait))
+                .map_or(Const::No, |attr| Const::Yes(attr.span)),
             kind => {
                 span_bug!(item.span, "assoc item has unexpected kind of parent: {}", kind.descr())
             }
         };
 
-        if self.tcx.features().effects {
-            self.host_param_id = generics
-                .params
-                .iter()
-                .find(|param| {
-                    matches!(param.kind, hir::GenericParamKind::Const { is_host_effect: true, .. })
-                })
-                .map(|param| param.def_id);
-        }
-
         match ctxt {
-            AssocCtxt::Trait => hir::OwnerNode::TraitItem(self.lower_trait_item(item)),
-            AssocCtxt::Impl => hir::OwnerNode::ImplItem(self.lower_impl_item(item)),
+            AssocCtxt::Trait => hir::OwnerNode::TraitItem(self.lower_trait_item(item, constness)),
+            AssocCtxt::Impl => hir::OwnerNode::ImplItem(self.lower_impl_item(item, constness)),
         }
     }
 
@@ -648,7 +662,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     let fdec = &sig.decl;
                     let itctx = ImplTraitContext::Universal;
                     let (generics, (fn_dec, fn_args)) =
-                        self.lower_generics(generics, Const::No, i.id, itctx, |this| {
+                        self.lower_generics(generics, Const::No, false, i.id, itctx, |this| {
                             (
                                 // Disallow `impl Trait` in foreign items.
                                 this.lower_fn_decl(
@@ -765,7 +779,11 @@ impl<'hir> LoweringContext<'_, 'hir> {
         }
     }
 
-    fn lower_trait_item(&mut self, i: &AssocItem) -> &'hir hir::TraitItem<'hir> {
+    fn lower_trait_item(
+        &mut self,
+        i: &AssocItem,
+        trait_constness: Const,
+    ) -> &'hir hir::TraitItem<'hir> {
         let hir_id = self.lower_node_id(i.id);
         self.lower_attrs(hir_id, &i.attrs);
         let trait_item_def_id = hir_id.expect_owner();
@@ -775,6 +793,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 let (generics, kind) = self.lower_generics(
                     generics,
                     Const::No,
+                    false,
                     i.id,
                     ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
                     |this| {
@@ -795,6 +814,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     i.id,
                     FnDeclKind::Trait,
                     sig.header.coroutine_kind,
+                    trait_constness,
                 );
                 (generics, hir::TraitItemKind::Fn(sig, hir::TraitFn::Required(names)), false)
             }
@@ -813,6 +833,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     i.id,
                     FnDeclKind::Trait,
                     sig.header.coroutine_kind,
+                    trait_constness,
                 );
                 (generics, hir::TraitItemKind::Fn(sig, hir::TraitFn::Provided(body_id)), true)
             }
@@ -822,6 +843,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 let (generics, kind) = self.lower_generics(
                     &generics,
                     Const::No,
+                    false,
                     i.id,
                     ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
                     |this| {
@@ -894,7 +916,11 @@ impl<'hir> LoweringContext<'_, 'hir> {
         self.expr(span, hir::ExprKind::Err(guar))
     }
 
-    fn lower_impl_item(&mut self, i: &AssocItem) -> &'hir hir::ImplItem<'hir> {
+    fn lower_impl_item(
+        &mut self,
+        i: &AssocItem,
+        constness_of_trait: Const,
+    ) -> &'hir hir::ImplItem<'hir> {
         // Since `default impl` is not yet implemented, this is always true in impls.
         let has_value = true;
         let (defaultness, _) = self.lower_defaultness(i.kind.defaultness(), has_value);
@@ -905,6 +931,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
             AssocItemKind::Const(box ConstItem { generics, ty, expr, .. }) => self.lower_generics(
                 generics,
                 Const::No,
+                false,
                 i.id,
                 ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
                 |this| {
@@ -930,6 +957,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     i.id,
                     if self.is_in_trait_impl { FnDeclKind::Impl } else { FnDeclKind::Inherent },
                     sig.header.coroutine_kind,
+                    constness_of_trait,
                 );
 
                 (generics, hir::ImplItemKind::Fn(sig, body_id))
@@ -940,6 +968,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 self.lower_generics(
                     &generics,
                     Const::No,
+                    false,
                     i.id,
                     ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
                     |this| match ty {
@@ -1352,15 +1381,18 @@ impl<'hir> LoweringContext<'_, 'hir> {
         id: NodeId,
         kind: FnDeclKind,
         coroutine_kind: Option<CoroutineKind>,
+        parent_constness: Const,
     ) -> (&'hir hir::Generics<'hir>, hir::FnSig<'hir>) {
         let header = self.lower_fn_header(sig.header);
         // Don't pass along the user-provided constness of trait associated functions; we don't want to
         // synthesize a host effect param for them. We reject `const` on them during AST validation.
-        let constness = if kind == FnDeclKind::Inherent { sig.header.constness } else { Const::No };
+        let constness =
+            if kind == FnDeclKind::Inherent { sig.header.constness } else { parent_constness };
         let itctx = ImplTraitContext::Universal;
-        let (generics, decl) = self.lower_generics(generics, constness, id, itctx, |this| {
-            this.lower_fn_decl(&sig.decl, id, sig.span, kind, coroutine_kind)
-        });
+        let (generics, decl) =
+            self.lower_generics(generics, constness, kind == FnDeclKind::Impl, id, itctx, |this| {
+                this.lower_fn_decl(&sig.decl, id, sig.span, kind, coroutine_kind)
+            });
         (generics, hir::FnSig { header, decl, span: self.lower_span(sig.span) })
     }
 
@@ -1436,6 +1468,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         &mut self,
         generics: &Generics,
         constness: Const,
+        force_append_constness: bool,
         parent_node_id: NodeId,
         itctx: ImplTraitContext,
         f: impl FnOnce(&mut Self) -> T,
@@ -1496,7 +1529,9 @@ impl<'hir> LoweringContext<'_, 'hir> {
         // if the effects feature is enabled. This needs to be done before we lower where
         // clauses since where clauses need to bind to the DefId of the host param
         let host_param_parts = if let Const::Yes(span) = constness
-            && self.tcx.features().effects
+            // if this comes from implementing a `const` trait, we must force constness to be appended
+            // to the impl item, no matter whether effects is enabled.
+            && (self.tcx.features().effects || force_append_constness)
         {
             let span = self.lower_span(span);
             let param_node_id = self.next_node_id();
@@ -1609,6 +1644,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                             }),
                         )),
                     )),
+                    // FIXME(effects) we might not need a default.
                     default: Some(self.arena.alloc(hir::AnonConst {
                         def_id: anon_const,
                         hir_id: const_id,
@@ -1616,6 +1652,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                         span,
                     })),
                     is_host_effect: true,
+                    synthetic: true,
                 },
                 colon_span: None,
                 pure_wrt_drop: false,
diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs
index 0a06304fcec..8fba46625ab 100644
--- a/compiler/rustc_ast_lowering/src/lib.rs
+++ b/compiler/rustc_ast_lowering/src/lib.rs
@@ -142,14 +142,19 @@ struct LoweringContext<'a, 'hir> {
     generics_def_id_map: Vec<LocalDefIdMap<LocalDefId>>,
 
     host_param_id: Option<LocalDefId>,
+    ast_index: &'a IndexSlice<LocalDefId, AstOwner<'a>>,
 }
 
 impl<'a, 'hir> LoweringContext<'a, 'hir> {
-    fn new(tcx: TyCtxt<'hir>, resolver: &'a mut ResolverAstLowering) -> Self {
+    fn new(
+        tcx: TyCtxt<'hir>,
+        resolver: &'a mut ResolverAstLowering,
+        ast_index: &'a IndexSlice<LocalDefId, AstOwner<'a>>,
+    ) -> Self {
         Self {
             // Pseudo-globals.
             tcx,
-            resolver: resolver,
+            resolver,
             arena: tcx.hir_arena,
 
             // HirId handling.
@@ -185,6 +190,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             allow_async_iterator: [sym::gen_future, sym::async_iterator].into(),
             generics_def_id_map: Default::default(),
             host_param_id: None,
+            ast_index,
         }
     }
 
@@ -2135,7 +2141,11 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         param: &GenericParam,
         source: hir::GenericParamSource,
     ) -> hir::GenericParam<'hir> {
-        let (name, kind) = self.lower_generic_param_kind(param, source);
+        let (name, kind) = self.lower_generic_param_kind(
+            param,
+            source,
+            attr::contains_name(&param.attrs, sym::rustc_runtime),
+        );
 
         let hir_id = self.lower_node_id(param.id);
         self.lower_attrs(hir_id, &param.attrs);
@@ -2155,6 +2165,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         &mut self,
         param: &GenericParam,
         source: hir::GenericParamSource,
+        is_host_effect: bool,
     ) -> (hir::ParamName, hir::GenericParamKind<'hir>) {
         match &param.kind {
             GenericParamKind::Lifetime => {
@@ -2220,7 +2231,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
 
                 (
                     hir::ParamName::Plain(self.lower_ident(param.ident)),
-                    hir::GenericParamKind::Const { ty, default, is_host_effect: false },
+                    hir::GenericParamKind::Const { ty, default, is_host_effect, synthetic: false },
                 )
             }
         }
@@ -2607,78 +2618,6 @@ struct GenericArgsCtor<'hir> {
 }
 
 impl<'hir> GenericArgsCtor<'hir> {
-    fn push_constness(
-        &mut self,
-        lcx: &mut LoweringContext<'_, 'hir>,
-        constness: ast::BoundConstness,
-    ) {
-        if !lcx.tcx.features().effects {
-            return;
-        }
-
-        let (span, body) = match constness {
-            BoundConstness::Never => return,
-            BoundConstness::Always(span) => {
-                let span = lcx.lower_span(span);
-
-                let body = hir::ExprKind::Lit(
-                    lcx.arena.alloc(hir::Lit { node: LitKind::Bool(false), span }),
-                );
-
-                (span, body)
-            }
-            BoundConstness::Maybe(span) => {
-                let span = lcx.lower_span(span);
-
-                let Some(host_param_id) = lcx.host_param_id else {
-                    lcx.dcx().span_delayed_bug(
-                        span,
-                        "no host param id for call in const yet no errors reported",
-                    );
-                    return;
-                };
-
-                let hir_id = lcx.next_id();
-                let res = Res::Def(DefKind::ConstParam, host_param_id.to_def_id());
-                let body = hir::ExprKind::Path(hir::QPath::Resolved(
-                    None,
-                    lcx.arena.alloc(hir::Path {
-                        span,
-                        res,
-                        segments: arena_vec![
-                            lcx;
-                            hir::PathSegment::new(
-                                Ident { name: sym::host, span },
-                                hir_id,
-                                res
-                            )
-                        ],
-                    }),
-                ));
-
-                (span, body)
-            }
-        };
-        let body = lcx.lower_body(|lcx| (&[], lcx.expr(span, body)));
-
-        let id = lcx.next_node_id();
-        let hir_id = lcx.next_id();
-
-        let def_id = lcx.create_def(
-            lcx.current_hir_id_owner.def_id,
-            id,
-            kw::Empty,
-            DefKind::AnonConst,
-            span,
-        );
-
-        lcx.children.push((def_id, hir::MaybeOwner::NonOwner(hir_id)));
-        self.args.push(hir::GenericArg::Const(hir::ConstArg {
-            value: lcx.arena.alloc(hir::AnonConst { def_id, hir_id, body, span }),
-            is_desugared_from_effects: true,
-        }))
-    }
-
     fn is_empty(&self) -> bool {
         self.args.is_empty()
             && self.constraints.is_empty()
diff --git a/compiler/rustc_ast_lowering/src/path.rs b/compiler/rustc_ast_lowering/src/path.rs
index 9d38e1e6784..9a1ca703699 100644
--- a/compiler/rustc_ast_lowering/src/path.rs
+++ b/compiler/rustc_ast_lowering/src/path.rs
@@ -107,8 +107,6 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                         param_mode,
                         parenthesized_generic_args,
                         itctx,
-                        // if this is the last segment, add constness to the trait path
-                        if i == proj_start - 1 { modifiers.map(|m| m.constness) } else { None },
                         bound_modifier_allowed_features.clone(),
                     )
                 },
@@ -165,7 +163,6 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                 ParenthesizedGenericArgs::Err,
                 itctx,
                 None,
-                None,
             ));
             let qpath = hir::QPath::TypeRelative(ty, hir_segment);
 
@@ -208,7 +205,6 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     ParenthesizedGenericArgs::Err,
                     ImplTraitContext::Disallowed(ImplTraitPosition::Path),
                     None,
-                    None,
                 )
             })),
             span: self.lower_span(p.span),
@@ -222,7 +218,6 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         param_mode: ParamMode,
         parenthesized_generic_args: ParenthesizedGenericArgs,
         itctx: ImplTraitContext,
-        constness: Option<ast::BoundConstness>,
         // Additional features ungated with a bound modifier like `async`.
         // This is passed down to the implicit associated type binding in
         // parenthesized bounds.
@@ -289,10 +284,6 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             )
         };
 
-        if let Some(constness) = constness {
-            generic_args.push_constness(self, constness);
-        }
-
         let has_lifetimes =
             generic_args.args.iter().any(|arg| matches!(arg, GenericArg::Lifetime(_)));
 
diff --git a/compiler/rustc_ast_passes/src/ast_validation.rs b/compiler/rustc_ast_passes/src/ast_validation.rs
index ba4b6130b60..022f953c6e7 100644
--- a/compiler/rustc_ast_passes/src/ast_validation.rs
+++ b/compiler/rustc_ast_passes/src/ast_validation.rs
@@ -1,10 +1,20 @@
-// Validate AST before lowering it to HIR.
-//
-// This pass is supposed to catch things that fit into AST data structures,
-// but not permitted by the language. It runs after expansion when AST is frozen,
-// so it can check for erroneous constructions produced by syntax extensions.
-// This pass is supposed to perform only simple checks not requiring name resolution
-// or type checking or some other kind of complex analysis.
+//! Validate AST before lowering it to HIR.
+//!
+//! This pass intends to check that the constructed AST is *syntactically valid* to allow the rest
+//! of the compiler to assume that the AST is valid. These checks cannot be performed during parsing
+//! because attribute macros are allowed to accept certain pieces of invalid syntax such as a
+//! function without body outside of a trait definition:
+//!
+//! ```ignore (illustrative)
+//! #[my_attribute]
+//! mod foo {
+//!     fn missing_body();
+//! }
+//! ```
+//!
+//! These checks are run post-expansion, after AST is frozen, to be able to check for erroneous
+//! constructions produced by proc macros. This pass is only intended for simple checks that do not
+//! require name resolution or type checking, or other kinds of complex analysis.
 
 use itertools::{Either, Itertools};
 use rustc_ast::ptr::P;
@@ -459,13 +469,18 @@ impl<'a> AstValidator<'a> {
     fn check_item_safety(&self, span: Span, safety: Safety) {
         match self.extern_mod_safety {
             Some(extern_safety) => {
-                if matches!(safety, Safety::Unsafe(_) | Safety::Safe(_))
-                    && (extern_safety == Safety::Default || !self.features.unsafe_extern_blocks)
-                {
-                    self.dcx().emit_err(errors::InvalidSafetyOnExtern {
-                        item_span: span,
-                        block: self.current_extern_span().shrink_to_lo(),
-                    });
+                if matches!(safety, Safety::Unsafe(_) | Safety::Safe(_)) {
+                    if extern_safety == Safety::Default {
+                        self.dcx().emit_err(errors::InvalidSafetyOnExtern {
+                            item_span: span,
+                            block: Some(self.current_extern_span().shrink_to_lo()),
+                        });
+                    } else if !self.features.unsafe_extern_blocks {
+                        self.dcx().emit_err(errors::InvalidSafetyOnExtern {
+                            item_span: span,
+                            block: None,
+                        });
+                    }
                 }
             }
             None => {
@@ -1088,7 +1103,15 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
                             }
                         }
                     } else if let &Safety::Unsafe(span) = safety {
-                        this.dcx().emit_err(errors::UnsafeItem { span, kind: "extern block" });
+                        let mut diag = this
+                            .dcx()
+                            .create_err(errors::UnsafeItem { span, kind: "extern block" });
+                        rustc_session::parse::add_feature_diagnostics(
+                            &mut diag,
+                            self.session,
+                            sym::unsafe_extern_blocks,
+                        );
+                        diag.emit();
                     }
 
                     if abi.is_none() {
diff --git a/compiler/rustc_ast_passes/src/errors.rs b/compiler/rustc_ast_passes/src/errors.rs
index 965d8fac712..bfb90476450 100644
--- a/compiler/rustc_ast_passes/src/errors.rs
+++ b/compiler/rustc_ast_passes/src/errors.rs
@@ -222,7 +222,7 @@ pub struct InvalidSafetyOnExtern {
     #[primary_span]
     pub item_span: Span,
     #[suggestion(code = "unsafe ", applicability = "machine-applicable", style = "verbose")]
-    pub block: Span,
+    pub block: Option<Span>,
 }
 
 #[derive(Diagnostic)]
diff --git a/compiler/rustc_borrowck/src/borrowck_errors.rs b/compiler/rustc_borrowck/src/borrowck_errors.rs
index f26f8711dd4..8eb44458137 100644
--- a/compiler/rustc_borrowck/src/borrowck_errors.rs
+++ b/compiler/rustc_borrowck/src/borrowck_errors.rs
@@ -6,8 +6,8 @@ use rustc_middle::span_bug;
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_span::Span;
 
-impl<'tcx> crate::MirBorrowckCtxt<'_, '_, '_, 'tcx> {
-    pub fn dcx(&self) -> DiagCtxtHandle<'tcx> {
+impl<'infcx, 'tcx> crate::MirBorrowckCtxt<'_, '_, 'infcx, 'tcx> {
+    pub fn dcx(&self) -> DiagCtxtHandle<'infcx> {
         self.infcx.dcx()
     }
 
@@ -18,7 +18,7 @@ impl<'tcx> crate::MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         place: &str,
         borrow_place: &str,
         value_place: &str,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'infcx> {
         self.dcx().create_err(crate::session_diagnostics::MoveBorrow {
             place,
             span,
@@ -34,7 +34,7 @@ impl<'tcx> crate::MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         desc: &str,
         borrow_span: Span,
         borrow_desc: &str,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'infcx> {
         struct_span_code_err!(
             self.dcx(),
             span,
@@ -54,7 +54,7 @@ impl<'tcx> crate::MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         old_loan_span: Span,
         old_opt_via: &str,
         old_load_end_span: Option<Span>,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'infcx> {
         let via = |msg: &str| if msg.is_empty() { "".to_string() } else { format!(" (via {msg})") };
         let mut err = struct_span_code_err!(
             self.dcx(),
@@ -101,7 +101,7 @@ impl<'tcx> crate::MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         desc: &str,
         old_loan_span: Span,
         old_load_end_span: Option<Span>,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'infcx> {
         let mut err = struct_span_code_err!(
             self.dcx(),
             new_loan_span,
@@ -134,7 +134,7 @@ impl<'tcx> crate::MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         noun_old: &str,
         old_opt_via: &str,
         previous_end_span: Option<Span>,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'infcx> {
         let mut err = struct_span_code_err!(
             self.dcx(),
             new_loan_span,
@@ -166,7 +166,7 @@ impl<'tcx> crate::MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         old_opt_via: &str,
         previous_end_span: Option<Span>,
         second_borrow_desc: &str,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'infcx> {
         let mut err = struct_span_code_err!(
             self.dcx(),
             new_loan_span,
@@ -198,7 +198,7 @@ impl<'tcx> crate::MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         kind_old: &str,
         msg_old: &str,
         old_load_end_span: Option<Span>,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'infcx> {
         let via = |msg: &str| if msg.is_empty() { "".to_string() } else { format!(" (via {msg})") };
         let mut err = struct_span_code_err!(
             self.dcx(),
@@ -239,7 +239,7 @@ impl<'tcx> crate::MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         span: Span,
         borrow_span: Span,
         desc: &str,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'infcx> {
         struct_span_code_err!(
             self.dcx(),
             span,
@@ -256,12 +256,12 @@ impl<'tcx> crate::MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         span: Span,
         desc: &str,
         is_arg: bool,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'infcx> {
         let msg = if is_arg { "to immutable argument" } else { "twice to immutable variable" };
         struct_span_code_err!(self.dcx(), span, E0384, "cannot assign {} {}", msg, desc)
     }
 
-    pub(crate) fn cannot_assign(&self, span: Span, desc: &str) -> Diag<'tcx> {
+    pub(crate) fn cannot_assign(&self, span: Span, desc: &str) -> Diag<'infcx> {
         struct_span_code_err!(self.dcx(), span, E0594, "cannot assign to {}", desc)
     }
 
@@ -269,7 +269,7 @@ impl<'tcx> crate::MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         &self,
         move_from_span: Span,
         move_from_desc: &str,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'infcx> {
         struct_span_code_err!(
             self.dcx(),
             move_from_span,
@@ -287,7 +287,7 @@ impl<'tcx> crate::MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         move_from_span: Span,
         ty: Ty<'_>,
         is_index: Option<bool>,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'infcx> {
         let type_name = match (&ty.kind(), is_index) {
             (&ty::Array(_, _), Some(true)) | (&ty::Array(_, _), None) => "array",
             (&ty::Slice(_), _) => "slice",
@@ -308,7 +308,7 @@ impl<'tcx> crate::MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         &self,
         move_from_span: Span,
         container_ty: Ty<'_>,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'infcx> {
         struct_span_code_err!(
             self.dcx(),
             move_from_span,
@@ -325,7 +325,7 @@ impl<'tcx> crate::MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         verb: &str,
         optional_adverb_for_moved: &str,
         moved_path: Option<String>,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'infcx> {
         let moved_path = moved_path.map(|mp| format!(": `{mp}`")).unwrap_or_default();
 
         struct_span_code_err!(
@@ -344,7 +344,7 @@ impl<'tcx> crate::MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         span: Span,
         path: &str,
         reason: &str,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'infcx> {
         struct_span_code_err!(
             self.dcx(),
             span,
@@ -362,7 +362,7 @@ impl<'tcx> crate::MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         immutable_place: &str,
         immutable_section: &str,
         action: &str,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'infcx> {
         struct_span_code_err!(
             self.dcx(),
             mutate_span,
@@ -380,7 +380,7 @@ impl<'tcx> crate::MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         &self,
         span: Span,
         yield_span: Span,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'infcx> {
         let coroutine_kind = self.body.coroutine.as_ref().unwrap().coroutine_kind;
         struct_span_code_err!(
             self.dcx(),
@@ -391,7 +391,7 @@ impl<'tcx> crate::MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         .with_span_label(yield_span, "possible yield occurs here")
     }
 
-    pub(crate) fn cannot_borrow_across_destructor(&self, borrow_span: Span) -> Diag<'tcx> {
+    pub(crate) fn cannot_borrow_across_destructor(&self, borrow_span: Span) -> Diag<'infcx> {
         struct_span_code_err!(
             self.dcx(),
             borrow_span,
@@ -400,7 +400,7 @@ impl<'tcx> crate::MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         )
     }
 
-    pub(crate) fn path_does_not_live_long_enough(&self, span: Span, path: &str) -> Diag<'tcx> {
+    pub(crate) fn path_does_not_live_long_enough(&self, span: Span, path: &str) -> Diag<'infcx> {
         struct_span_code_err!(self.dcx(), span, E0597, "{} does not live long enough", path,)
     }
 
@@ -410,7 +410,7 @@ impl<'tcx> crate::MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         return_kind: &str,
         reference_desc: &str,
         path_desc: &str,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'infcx> {
         struct_span_code_err!(
             self.dcx(),
             span,
@@ -433,7 +433,7 @@ impl<'tcx> crate::MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         borrowed_path: &str,
         capture_span: Span,
         scope: &str,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'infcx> {
         struct_span_code_err!(
             self.dcx(),
             closure_span,
@@ -445,7 +445,7 @@ impl<'tcx> crate::MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         .with_span_label(closure_span, format!("may outlive borrowed value {borrowed_path}"))
     }
 
-    pub(crate) fn thread_local_value_does_not_live_long_enough(&self, span: Span) -> Diag<'tcx> {
+    pub(crate) fn thread_local_value_does_not_live_long_enough(&self, span: Span) -> Diag<'infcx> {
         struct_span_code_err!(
             self.dcx(),
             span,
@@ -454,7 +454,7 @@ impl<'tcx> crate::MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         )
     }
 
-    pub(crate) fn temporary_value_borrowed_for_too_long(&self, span: Span) -> Diag<'tcx> {
+    pub(crate) fn temporary_value_borrowed_for_too_long(&self, span: Span) -> Diag<'infcx> {
         struct_span_code_err!(self.dcx(), span, E0716, "temporary value dropped while borrowed",)
     }
 }
diff --git a/compiler/rustc_borrowck/src/dataflow.rs b/compiler/rustc_borrowck/src/dataflow.rs
index f2b5ddcd782..00a30dc2240 100644
--- a/compiler/rustc_borrowck/src/dataflow.rs
+++ b/compiler/rustc_borrowck/src/dataflow.rs
@@ -15,24 +15,24 @@ use std::fmt;
 use crate::{places_conflict, BorrowSet, PlaceConflictBias, PlaceExt, RegionInferenceContext};
 
 /// The results of the dataflow analyses used by the borrow checker.
-pub struct BorrowckResults<'mir, 'tcx> {
-    pub(crate) borrows: Results<'tcx, Borrows<'mir, 'tcx>>,
-    pub(crate) uninits: Results<'tcx, MaybeUninitializedPlaces<'mir, 'tcx>>,
-    pub(crate) ever_inits: Results<'tcx, EverInitializedPlaces<'mir, 'tcx>>,
+pub struct BorrowckResults<'a, 'mir, 'tcx> {
+    pub(crate) borrows: Results<'tcx, Borrows<'a, 'mir, 'tcx>>,
+    pub(crate) uninits: Results<'tcx, MaybeUninitializedPlaces<'a, 'mir, 'tcx>>,
+    pub(crate) ever_inits: Results<'tcx, EverInitializedPlaces<'a, 'mir, 'tcx>>,
 }
 
 /// The transient state of the dataflow analyses used by the borrow checker.
 #[derive(Debug)]
-pub struct BorrowckFlowState<'mir, 'tcx> {
-    pub(crate) borrows: <Borrows<'mir, 'tcx> as AnalysisDomain<'tcx>>::Domain,
-    pub(crate) uninits: <MaybeUninitializedPlaces<'mir, 'tcx> as AnalysisDomain<'tcx>>::Domain,
-    pub(crate) ever_inits: <EverInitializedPlaces<'mir, 'tcx> as AnalysisDomain<'tcx>>::Domain,
+pub struct BorrowckFlowState<'a, 'mir, 'tcx> {
+    pub(crate) borrows: <Borrows<'a, 'mir, 'tcx> as AnalysisDomain<'tcx>>::Domain,
+    pub(crate) uninits: <MaybeUninitializedPlaces<'a, 'mir, 'tcx> as AnalysisDomain<'tcx>>::Domain,
+    pub(crate) ever_inits: <EverInitializedPlaces<'a, 'mir, 'tcx> as AnalysisDomain<'tcx>>::Domain,
 }
 
-impl<'mir, 'tcx> ResultsVisitable<'tcx> for BorrowckResults<'mir, 'tcx> {
+impl<'a, 'mir, 'tcx> ResultsVisitable<'tcx> for BorrowckResults<'a, 'mir, 'tcx> {
     // All three analyses are forward, but we have to use just one here.
-    type Direction = <Borrows<'mir, 'tcx> as AnalysisDomain<'tcx>>::Direction;
-    type FlowState = BorrowckFlowState<'mir, 'tcx>;
+    type Direction = <Borrows<'a, 'mir, 'tcx> as AnalysisDomain<'tcx>>::Direction;
+    type FlowState = BorrowckFlowState<'a, 'mir, 'tcx>;
 
     fn new_flow_state(&self, body: &mir::Body<'tcx>) -> Self::FlowState {
         BorrowckFlowState {
@@ -106,11 +106,11 @@ rustc_index::newtype_index! {
 /// `BorrowIndex`, and maps each such index to a `BorrowData`
 /// describing the borrow. These indexes are used for representing the
 /// borrows in compact bitvectors.
-pub struct Borrows<'mir, 'tcx> {
+pub struct Borrows<'a, 'mir, 'tcx> {
     tcx: TyCtxt<'tcx>,
     body: &'mir Body<'tcx>,
 
-    borrow_set: &'mir BorrowSet<'tcx>,
+    borrow_set: &'a BorrowSet<'tcx>,
     borrows_out_of_scope_at_location: FxIndexMap<Location, Vec<BorrowIndex>>,
 }
 
@@ -389,12 +389,12 @@ impl<'tcx> PoloniusOutOfScopePrecomputer<'_, 'tcx> {
     }
 }
 
-impl<'mir, 'tcx> Borrows<'mir, 'tcx> {
+impl<'a, 'mir, 'tcx> Borrows<'a, 'mir, 'tcx> {
     pub fn new(
         tcx: TyCtxt<'tcx>,
         body: &'mir Body<'tcx>,
-        regioncx: &'mir RegionInferenceContext<'tcx>,
-        borrow_set: &'mir BorrowSet<'tcx>,
+        regioncx: &RegionInferenceContext<'tcx>,
+        borrow_set: &'a BorrowSet<'tcx>,
     ) -> Self {
         let mut borrows_out_of_scope_at_location =
             calculate_borrows_out_of_scope_at_location(body, regioncx, borrow_set);
@@ -494,7 +494,7 @@ impl<'mir, 'tcx> Borrows<'mir, 'tcx> {
     }
 }
 
-impl<'tcx> rustc_mir_dataflow::AnalysisDomain<'tcx> for Borrows<'_, 'tcx> {
+impl<'tcx> rustc_mir_dataflow::AnalysisDomain<'tcx> for Borrows<'_, '_, 'tcx> {
     type Domain = BitSet<BorrowIndex>;
 
     const NAME: &'static str = "borrows";
@@ -517,7 +517,7 @@ impl<'tcx> rustc_mir_dataflow::AnalysisDomain<'tcx> for Borrows<'_, 'tcx> {
 ///   region stops containing the CFG points reachable from the issuing location.
 /// - we also kill loans of conflicting places when overwriting a shared path: e.g. borrows of
 ///   `a.b.c` when `a` is overwritten.
-impl<'tcx> rustc_mir_dataflow::GenKillAnalysis<'tcx> for Borrows<'_, 'tcx> {
+impl<'tcx> rustc_mir_dataflow::GenKillAnalysis<'tcx> for Borrows<'_, '_, 'tcx> {
     type Idx = BorrowIndex;
 
     fn domain_size(&self, _: &mir::Body<'tcx>) -> usize {
@@ -617,8 +617,8 @@ impl<'tcx> rustc_mir_dataflow::GenKillAnalysis<'tcx> for Borrows<'_, 'tcx> {
     }
 }
 
-impl DebugWithContext<Borrows<'_, '_>> for BorrowIndex {
-    fn fmt_with(&self, ctxt: &Borrows<'_, '_>, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+impl DebugWithContext<Borrows<'_, '_, '_>> for BorrowIndex {
+    fn fmt_with(&self, ctxt: &Borrows<'_, '_, '_>, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(f, "{:?}", ctxt.location(*self))
     }
 }
diff --git a/compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs b/compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs
index d46febffba8..8bf3e670ff2 100644
--- a/compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs
@@ -149,13 +149,13 @@ trait TypeOpInfo<'tcx> {
 
     fn base_universe(&self) -> ty::UniverseIndex;
 
-    fn nice_error(
+    fn nice_error<'infcx>(
         &self,
-        mbcx: &mut MirBorrowckCtxt<'_, '_, '_, 'tcx>,
+        mbcx: &mut MirBorrowckCtxt<'_, '_, 'infcx, 'tcx>,
         cause: ObligationCause<'tcx>,
         placeholder_region: ty::Region<'tcx>,
         error_region: Option<ty::Region<'tcx>>,
-    ) -> Option<Diag<'tcx>>;
+    ) -> Option<Diag<'infcx>>;
 
     #[instrument(level = "debug", skip(self, mbcx))]
     fn report_error(
@@ -231,18 +231,25 @@ impl<'tcx> TypeOpInfo<'tcx> for PredicateQuery<'tcx> {
         self.base_universe
     }
 
-    fn nice_error(
+    fn nice_error<'infcx>(
         &self,
-        mbcx: &mut MirBorrowckCtxt<'_, '_, '_, 'tcx>,
+        mbcx: &mut MirBorrowckCtxt<'_, '_, 'infcx, 'tcx>,
         cause: ObligationCause<'tcx>,
         placeholder_region: ty::Region<'tcx>,
         error_region: Option<ty::Region<'tcx>>,
-    ) -> Option<Diag<'tcx>> {
+    ) -> Option<Diag<'infcx>> {
         let (infcx, key, _) =
             mbcx.infcx.tcx.infer_ctxt().build_with_canonical(cause.span, &self.canonical_query);
         let ocx = ObligationCtxt::new(&infcx);
         type_op_prove_predicate_with_cause(&ocx, key, cause);
-        try_extract_error_from_fulfill_cx(&ocx, mbcx.mir_def_id(), placeholder_region, error_region)
+        let diag = try_extract_error_from_fulfill_cx(
+            &ocx,
+            mbcx.mir_def_id(),
+            placeholder_region,
+            error_region,
+        )?
+        .with_dcx(mbcx.dcx());
+        Some(diag)
     }
 }
 
@@ -268,13 +275,13 @@ where
         self.base_universe
     }
 
-    fn nice_error(
+    fn nice_error<'infcx>(
         &self,
-        mbcx: &mut MirBorrowckCtxt<'_, '_, '_, 'tcx>,
+        mbcx: &mut MirBorrowckCtxt<'_, '_, 'infcx, 'tcx>,
         cause: ObligationCause<'tcx>,
         placeholder_region: ty::Region<'tcx>,
         error_region: Option<ty::Region<'tcx>>,
-    ) -> Option<Diag<'tcx>> {
+    ) -> Option<Diag<'infcx>> {
         let (infcx, key, _) =
             mbcx.infcx.tcx.infer_ctxt().build_with_canonical(cause.span, &self.canonical_query);
         let ocx = ObligationCtxt::new(&infcx);
@@ -288,7 +295,14 @@ where
         let (param_env, value) = key.into_parts();
         let _ = ocx.normalize(&cause, param_env, value.value);
 
-        try_extract_error_from_fulfill_cx(&ocx, mbcx.mir_def_id(), placeholder_region, error_region)
+        let diag = try_extract_error_from_fulfill_cx(
+            &ocx,
+            mbcx.mir_def_id(),
+            placeholder_region,
+            error_region,
+        )?
+        .with_dcx(mbcx.dcx());
+        Some(diag)
     }
 }
 
@@ -308,18 +322,25 @@ impl<'tcx> TypeOpInfo<'tcx> for AscribeUserTypeQuery<'tcx> {
         self.base_universe
     }
 
-    fn nice_error(
+    fn nice_error<'infcx>(
         &self,
-        mbcx: &mut MirBorrowckCtxt<'_, '_, '_, 'tcx>,
+        mbcx: &mut MirBorrowckCtxt<'_, '_, 'infcx, 'tcx>,
         cause: ObligationCause<'tcx>,
         placeholder_region: ty::Region<'tcx>,
         error_region: Option<ty::Region<'tcx>>,
-    ) -> Option<Diag<'tcx>> {
+    ) -> Option<Diag<'infcx>> {
         let (infcx, key, _) =
             mbcx.infcx.tcx.infer_ctxt().build_with_canonical(cause.span, &self.canonical_query);
         let ocx = ObligationCtxt::new(&infcx);
         type_op_ascribe_user_type_with_span(&ocx, key, Some(cause.span)).ok()?;
-        try_extract_error_from_fulfill_cx(&ocx, mbcx.mir_def_id(), placeholder_region, error_region)
+        let diag = try_extract_error_from_fulfill_cx(
+            &ocx,
+            mbcx.mir_def_id(),
+            placeholder_region,
+            error_region,
+        )?
+        .with_dcx(mbcx.dcx());
+        Some(diag)
     }
 }
 
@@ -334,13 +355,13 @@ impl<'tcx> TypeOpInfo<'tcx> for crate::type_check::InstantiateOpaqueType<'tcx> {
         self.base_universe.unwrap()
     }
 
-    fn nice_error(
+    fn nice_error<'infcx>(
         &self,
-        mbcx: &mut MirBorrowckCtxt<'_, '_, '_, 'tcx>,
+        mbcx: &mut MirBorrowckCtxt<'_, '_, 'infcx, 'tcx>,
         _cause: ObligationCause<'tcx>,
         placeholder_region: ty::Region<'tcx>,
         error_region: Option<ty::Region<'tcx>>,
-    ) -> Option<Diag<'tcx>> {
+    ) -> Option<Diag<'infcx>> {
         try_extract_error_from_region_constraints(
             mbcx.infcx,
             mbcx.mir_def_id(),
@@ -358,12 +379,12 @@ impl<'tcx> TypeOpInfo<'tcx> for crate::type_check::InstantiateOpaqueType<'tcx> {
 }
 
 #[instrument(skip(ocx), level = "debug")]
-fn try_extract_error_from_fulfill_cx<'tcx>(
-    ocx: &ObligationCtxt<'_, 'tcx>,
+fn try_extract_error_from_fulfill_cx<'a, 'tcx>(
+    ocx: &ObligationCtxt<'a, 'tcx>,
     generic_param_scope: LocalDefId,
     placeholder_region: ty::Region<'tcx>,
     error_region: Option<ty::Region<'tcx>>,
-) -> Option<Diag<'tcx>> {
+) -> Option<Diag<'a>> {
     // We generally shouldn't have errors here because the query was
     // already run, but there's no point using `span_delayed_bug`
     // when we're going to emit an error here anyway.
@@ -381,15 +402,15 @@ fn try_extract_error_from_fulfill_cx<'tcx>(
 }
 
 #[instrument(level = "debug", skip(infcx, region_var_origin, universe_of_region))]
-fn try_extract_error_from_region_constraints<'tcx>(
-    infcx: &InferCtxt<'tcx>,
+fn try_extract_error_from_region_constraints<'a, 'tcx>(
+    infcx: &'a InferCtxt<'tcx>,
     generic_param_scope: LocalDefId,
     placeholder_region: ty::Region<'tcx>,
     error_region: Option<ty::Region<'tcx>>,
     region_constraints: &RegionConstraintData<'tcx>,
     mut region_var_origin: impl FnMut(RegionVid) -> RegionVariableOrigin,
     mut universe_of_region: impl FnMut(RegionVid) -> UniverseIndex,
-) -> Option<Diag<'tcx>> {
+) -> Option<Diag<'a>> {
     let placeholder_universe = match placeholder_region.kind() {
         ty::RePlaceholder(p) => p.universe,
         ty::ReVar(vid) => universe_of_region(vid),
diff --git a/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs b/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
index 1cc7fee718e..44ab762f66e 100644
--- a/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
@@ -73,7 +73,7 @@ enum StorageDeadOrDrop<'tcx> {
     Destructor(Ty<'tcx>),
 }
 
-impl<'tcx> MirBorrowckCtxt<'_, '_, '_, 'tcx> {
+impl<'infcx, 'tcx> MirBorrowckCtxt<'_, '_, 'infcx, 'tcx> {
     pub(crate) fn report_use_of_moved_or_uninitialized(
         &mut self,
         location: Location,
@@ -341,7 +341,7 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, '_, 'tcx> {
     fn suggest_ref_or_clone(
         &self,
         mpi: MovePathIndex,
-        err: &mut Diag<'tcx>,
+        err: &mut Diag<'infcx>,
         in_pattern: &mut bool,
         move_spans: UseSpans<'tcx>,
     ) {
@@ -517,7 +517,7 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         desired_action: InitializationRequiringAction,
         span: Span,
         use_spans: UseSpans<'tcx>,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'infcx> {
         // We need all statements in the body where the binding was assigned to later find all
         // the branching code paths where the binding *wasn't* assigned to.
         let inits = &self.move_data.init_path_map[mpi];
@@ -1288,7 +1288,7 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, '_, 'tcx> {
             return false;
         }
         // Try to find predicates on *generic params* that would allow copying `ty`
-        let suggestion =
+        let mut suggestion =
             if let Some(symbol) = tcx.hir().maybe_get_struct_pattern_shorthand_field(expr) {
                 format!(": {symbol}.clone()")
             } else {
@@ -1296,6 +1296,8 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, '_, 'tcx> {
             };
         let mut sugg = Vec::with_capacity(2);
         let mut inner_expr = expr;
+        let mut is_raw_ptr = false;
+        let typeck_result = self.infcx.tcx.typeck(self.mir_def_id());
         // Remove uses of `&` and `*` when suggesting `.clone()`.
         while let hir::ExprKind::AddrOf(.., inner) | hir::ExprKind::Unary(hir::UnOp::Deref, inner) =
             &inner_expr.kind
@@ -1306,14 +1308,32 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, '_, 'tcx> {
                 return false;
             }
             inner_expr = inner;
+            if let Some(inner_type) = typeck_result.node_type_opt(inner.hir_id) {
+                if matches!(inner_type.kind(), ty::RawPtr(..)) {
+                    is_raw_ptr = true;
+                    break;
+                }
+            }
         }
-        if inner_expr.span.lo() != expr.span.lo() {
+        // Cloning the raw pointer doesn't make sense in some cases and would cause a type mismatch error. (see #126863)
+        if inner_expr.span.lo() != expr.span.lo() && !is_raw_ptr {
+            // Remove "(*" or "(&"
             sugg.push((expr.span.with_hi(inner_expr.span.lo()), String::new()));
         }
+        // Check whether `expr` is surrounded by parentheses or not.
         let span = if inner_expr.span.hi() != expr.span.hi() {
             // Account for `(*x)` to suggest `x.clone()`.
-            expr.span.with_lo(inner_expr.span.hi())
+            if is_raw_ptr {
+                expr.span.shrink_to_hi()
+            } else {
+                // Remove the close parenthesis ")"
+                expr.span.with_lo(inner_expr.span.hi())
+            }
         } else {
+            if is_raw_ptr {
+                sugg.push((expr.span.shrink_to_lo(), "(".to_string()));
+                suggestion = ").clone()".to_string();
+            }
             expr.span.shrink_to_hi()
         };
         sugg.push((span, suggestion));
@@ -1441,7 +1461,7 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         location: Location,
         (place, _span): (Place<'tcx>, Span),
         borrow: &BorrowData<'tcx>,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'infcx> {
         let borrow_spans = self.retrieve_borrow_spans(borrow);
         let borrow_span = borrow_spans.args_or_use();
 
@@ -1491,7 +1511,7 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         (place, span): (Place<'tcx>, Span),
         gen_borrow_kind: BorrowKind,
         issued_borrow: &BorrowData<'tcx>,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'infcx> {
         let issued_spans = self.retrieve_borrow_spans(issued_borrow);
         let issued_span = issued_spans.args_or_use();
 
@@ -1782,7 +1802,7 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         err
     }
 
-    fn suggest_copy_for_type_in_cloned_ref(&self, err: &mut Diag<'tcx>, place: Place<'tcx>) {
+    fn suggest_copy_for_type_in_cloned_ref(&self, err: &mut Diag<'infcx>, place: Place<'tcx>) {
         let tcx = self.infcx.tcx;
         let hir = tcx.hir();
         let Some(body_id) = tcx.hir_node(self.mir_hir_id()).body_id() else { return };
@@ -2841,7 +2861,7 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         drop_span: Span,
         borrow_spans: UseSpans<'tcx>,
         explanation: BorrowExplanation<'tcx>,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'infcx> {
         debug!(
             "report_local_value_does_not_live_long_enough(\
              {:?}, {:?}, {:?}, {:?}, {:?}\
@@ -3016,7 +3036,7 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         &self,
         drop_span: Span,
         borrow_span: Span,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'infcx> {
         debug!(
             "report_thread_local_value_does_not_live_long_enough(\
              {:?}, {:?}\
@@ -3041,7 +3061,7 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         borrow_spans: UseSpans<'tcx>,
         proper_span: Span,
         explanation: BorrowExplanation<'tcx>,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'infcx> {
         if let BorrowExplanation::MustBeValidFor { category, span, from_closure: false, .. } =
             explanation
         {
@@ -3206,7 +3226,7 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         return_span: Span,
         category: ConstraintCategory<'tcx>,
         opt_place_desc: Option<&String>,
-    ) -> Result<(), Diag<'tcx>> {
+    ) -> Result<(), Diag<'infcx>> {
         let return_kind = match category {
             ConstraintCategory::Return(_) => "return",
             ConstraintCategory::Yield => "yield",
@@ -3299,7 +3319,7 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         constraint_span: Span,
         captured_var: &str,
         scope: &str,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'infcx> {
         let tcx = self.infcx.tcx;
         let args_span = use_span.args_or_use();
 
@@ -3411,7 +3431,7 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         upvar_span: Span,
         upvar_name: Symbol,
         escape_span: Span,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'infcx> {
         let tcx = self.infcx.tcx;
 
         let escapes_from = tcx.def_descr(self.mir_def_id().to_def_id());
diff --git a/compiler/rustc_borrowck/src/diagnostics/mod.rs b/compiler/rustc_borrowck/src/diagnostics/mod.rs
index 842ed38f1e2..4567a014fe8 100644
--- a/compiler/rustc_borrowck/src/diagnostics/mod.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/mod.rs
@@ -69,7 +69,7 @@ pub(super) struct DescribePlaceOpt {
 
 pub(super) struct IncludingTupleField(pub(super) bool);
 
-impl<'tcx> MirBorrowckCtxt<'_, '_, '_, 'tcx> {
+impl<'infcx, 'tcx> MirBorrowckCtxt<'_, '_, 'infcx, 'tcx> {
     /// Adds a suggestion when a closure is invoked twice with a moved variable or when a closure
     /// is moved after being invoked.
     ///
@@ -86,7 +86,7 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         &self,
         location: Location,
         place: PlaceRef<'tcx>,
-        diag: &mut Diag<'_>,
+        diag: &mut Diag<'infcx>,
     ) -> bool {
         debug!("add_moved_or_invoked_closure_note: location={:?} place={:?}", location, place);
         let mut target = place.local_or_deref_local();
diff --git a/compiler/rustc_borrowck/src/diagnostics/move_errors.rs b/compiler/rustc_borrowck/src/diagnostics/move_errors.rs
index 12fa4c4f5ee..c817a80a541 100644
--- a/compiler/rustc_borrowck/src/diagnostics/move_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/move_errors.rs
@@ -93,7 +93,7 @@ enum GroupedMoveError<'tcx> {
     },
 }
 
-impl<'tcx> MirBorrowckCtxt<'_, '_, '_, 'tcx> {
+impl<'infcx, 'tcx> MirBorrowckCtxt<'_, '_, 'infcx, 'tcx> {
     pub(crate) fn report_move_errors(&mut self) {
         let grouped_errors = self.group_move_errors();
         for error in grouped_errors {
@@ -291,7 +291,7 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         self.buffer_error(err);
     }
 
-    fn report_cannot_move_from_static(&mut self, place: Place<'tcx>, span: Span) -> Diag<'tcx> {
+    fn report_cannot_move_from_static(&mut self, place: Place<'tcx>, span: Span) -> Diag<'infcx> {
         let description = if place.projection.len() == 1 {
             format!("static item {}", self.describe_any_place(place.as_ref()))
         } else {
@@ -428,7 +428,7 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         deref_target_place: Place<'tcx>,
         span: Span,
         use_spans: Option<UseSpans<'tcx>>,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'infcx> {
         let tcx = self.infcx.tcx;
         // Inspect the type of the content behind the
         // borrow to provide feedback about why this
@@ -639,12 +639,27 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, '_, 'tcx> {
     fn add_borrow_suggestions(&self, err: &mut Diag<'_>, span: Span) {
         match self.infcx.tcx.sess.source_map().span_to_snippet(span) {
             Ok(snippet) if snippet.starts_with('*') => {
-                err.span_suggestion_verbose(
-                    span.with_hi(span.lo() + BytePos(1)),
-                    "consider removing the dereference here",
-                    String::new(),
-                    Applicability::MaybeIncorrect,
-                );
+                let sp = span.with_lo(span.lo() + BytePos(1));
+                let inner = self.find_expr(sp);
+                let mut is_raw_ptr = false;
+                if let Some(inner) = inner {
+                    let typck_result = self.infcx.tcx.typeck(self.mir_def_id());
+                    if let Some(inner_type) = typck_result.node_type_opt(inner.hir_id) {
+                        if matches!(inner_type.kind(), ty::RawPtr(..)) {
+                            is_raw_ptr = true;
+                        }
+                    }
+                }
+                // If the `inner` is a raw pointer, do not suggest removing the "*", see #126863
+                // FIXME: need to check whether the assigned object can be a raw pointer, see `tests/ui/borrowck/issue-20801.rs`.
+                if !is_raw_ptr {
+                    err.span_suggestion_verbose(
+                        span.with_hi(span.lo() + BytePos(1)),
+                        "consider removing the dereference here",
+                        String::new(),
+                        Applicability::MaybeIncorrect,
+                    );
+                }
             }
             _ => {
                 err.span_suggestion_verbose(
diff --git a/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs b/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs
index 93fac3181ba..19a4df0cd7b 100644
--- a/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs
@@ -30,7 +30,7 @@ pub(crate) enum AccessKind {
     Mutate,
 }
 
-impl<'tcx> MirBorrowckCtxt<'_, '_, '_, 'tcx> {
+impl<'infcx, 'tcx> MirBorrowckCtxt<'_, '_, 'infcx, 'tcx> {
     pub(crate) fn report_mutability_error(
         &mut self,
         access_place: Place<'tcx>,
@@ -541,7 +541,7 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, '_, 'tcx> {
     }
 
     /// Suggest `map[k] = v` => `map.insert(k, v)` and the like.
-    fn suggest_map_index_mut_alternatives(&self, ty: Ty<'tcx>, err: &mut Diag<'tcx>, span: Span) {
+    fn suggest_map_index_mut_alternatives(&self, ty: Ty<'tcx>, err: &mut Diag<'infcx>, span: Span) {
         let Some(adt) = ty.ty_adt_def() else { return };
         let did = adt.did();
         if self.infcx.tcx.is_diagnostic_item(sym::HashMap, did)
@@ -550,13 +550,13 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, '_, 'tcx> {
             /// Walks through the HIR, looking for the corresponding span for this error.
             /// When it finds it, see if it corresponds to assignment operator whose LHS
             /// is an index expr.
-            struct SuggestIndexOperatorAlternativeVisitor<'a, 'tcx> {
+            struct SuggestIndexOperatorAlternativeVisitor<'a, 'infcx, 'tcx> {
                 assign_span: Span,
-                err: &'a mut Diag<'tcx>,
+                err: &'a mut Diag<'infcx>,
                 ty: Ty<'tcx>,
                 suggested: bool,
             }
-            impl<'a, 'tcx> Visitor<'tcx> for SuggestIndexOperatorAlternativeVisitor<'a, 'tcx> {
+            impl<'a, 'cx, 'tcx> Visitor<'tcx> for SuggestIndexOperatorAlternativeVisitor<'a, 'cx, 'tcx> {
                 fn visit_stmt(&mut self, stmt: &'tcx hir::Stmt<'tcx>) {
                     hir::intravisit::walk_stmt(self, stmt);
                     let expr = match stmt.kind {
diff --git a/compiler/rustc_borrowck/src/diagnostics/region_errors.rs b/compiler/rustc_borrowck/src/diagnostics/region_errors.rs
index db78edc45b9..fba18c38146 100644
--- a/compiler/rustc_borrowck/src/diagnostics/region_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/region_errors.rs
@@ -160,7 +160,7 @@ pub struct ErrorConstraintInfo<'tcx> {
     pub(super) span: Span,
 }
 
-impl<'tcx> MirBorrowckCtxt<'_, '_, '_, 'tcx> {
+impl<'infcx, 'tcx> MirBorrowckCtxt<'_, '_, 'infcx, 'tcx> {
     /// Converts a region inference variable into a `ty::Region` that
     /// we can use for error reporting. If `r` is universally bound,
     /// then we use the name that we have on record for it. If `r` is
@@ -360,7 +360,7 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, '_, 'tcx> {
                     let named_key = self.regioncx.name_regions(self.infcx.tcx, key);
                     let named_region = self.regioncx.name_regions(self.infcx.tcx, member_region);
                     let diag = unexpected_hidden_region_diagnostic(
-                        self.infcx.tcx,
+                        self.infcx,
                         self.mir_def_id(),
                         span,
                         named_ty,
@@ -589,7 +589,7 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, '_, 'tcx> {
         &self,
         errci: &ErrorConstraintInfo<'tcx>,
         kind: ReturnConstraint,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'infcx> {
         let ErrorConstraintInfo { outlived_fr, span, .. } = errci;
 
         let mut output_ty = self.regioncx.universal_regions().unnormalized_output_ty;
@@ -658,7 +658,7 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, '_, 'tcx> {
     ///    |     ^^^^^^^^^^ `x` escapes the function body here
     /// ```
     #[instrument(level = "debug", skip(self))]
-    fn report_escaping_data_error(&self, errci: &ErrorConstraintInfo<'tcx>) -> Diag<'tcx> {
+    fn report_escaping_data_error(&self, errci: &ErrorConstraintInfo<'tcx>) -> Diag<'infcx> {
         let ErrorConstraintInfo { span, category, .. } = errci;
 
         let fr_name_and_span = self.regioncx.get_var_name_and_span_for_region(
@@ -767,7 +767,7 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, '_, 'tcx> {
     ///    |                    is returning data with lifetime `'b`
     /// ```
     #[allow(rustc::diagnostic_outside_of_impl)] // FIXME
-    fn report_general_error(&self, errci: &ErrorConstraintInfo<'tcx>) -> Diag<'tcx> {
+    fn report_general_error(&self, errci: &ErrorConstraintInfo<'tcx>) -> Diag<'infcx> {
         let ErrorConstraintInfo {
             fr,
             fr_is_local,
diff --git a/compiler/rustc_borrowck/src/lib.rs b/compiler/rustc_borrowck/src/lib.rs
index 69efee2fbdc..e6f8ffd428d 100644
--- a/compiler/rustc_borrowck/src/lib.rs
+++ b/compiler/rustc_borrowck/src/lib.rs
@@ -310,8 +310,8 @@ fn do_mir_borrowck<'tcx>(
         promoted_mbcx.report_move_errors();
         diags = promoted_mbcx.diags;
 
-        struct MoveVisitor<'a, 'b, 'mir, 'cx, 'tcx> {
-            ctxt: &'a mut MirBorrowckCtxt<'b, 'mir, 'cx, 'tcx>,
+        struct MoveVisitor<'a, 'b, 'mir, 'infcx, 'tcx> {
+            ctxt: &'a mut MirBorrowckCtxt<'b, 'mir, 'infcx, 'tcx>,
         }
 
         impl<'tcx> Visitor<'tcx> for MoveVisitor<'_, '_, '_, '_, 'tcx> {
@@ -528,8 +528,8 @@ impl<'tcx> Deref for BorrowckInferCtxt<'tcx> {
     }
 }
 
-struct MirBorrowckCtxt<'a, 'mir, 'cx, 'tcx> {
-    infcx: &'cx BorrowckInferCtxt<'tcx>,
+struct MirBorrowckCtxt<'a, 'mir, 'infcx, 'tcx> {
+    infcx: &'infcx BorrowckInferCtxt<'tcx>,
     param_env: ParamEnv<'tcx>,
     body: &'mir Body<'tcx>,
     move_data: &'a MoveData<'tcx>,
@@ -596,7 +596,7 @@ struct MirBorrowckCtxt<'a, 'mir, 'cx, 'tcx> {
     /// Results of Polonius analysis.
     polonius_output: Option<Rc<PoloniusOutput>>,
 
-    diags: diags::BorrowckDiags<'tcx>,
+    diags: diags::BorrowckDiags<'infcx, 'tcx>,
     move_errors: Vec<MoveError<'tcx>>,
 }
 
@@ -605,15 +605,15 @@ struct MirBorrowckCtxt<'a, 'mir, 'cx, 'tcx> {
 // 2. loans made in overlapping scopes do not conflict
 // 3. assignments do not affect things loaned out as immutable
 // 4. moves do not affect things loaned out in any way
-impl<'mir, 'tcx, R> rustc_mir_dataflow::ResultsVisitor<'mir, 'tcx, R>
-    for MirBorrowckCtxt<'_, 'mir, '_, 'tcx>
+impl<'a, 'mir, 'tcx, R> rustc_mir_dataflow::ResultsVisitor<'mir, 'tcx, R>
+    for MirBorrowckCtxt<'a, 'mir, '_, 'tcx>
 {
-    type FlowState = Flows<'mir, 'tcx>;
+    type FlowState = Flows<'a, 'mir, 'tcx>;
 
     fn visit_statement_before_primary_effect(
         &mut self,
         _results: &mut R,
-        flow_state: &Flows<'mir, 'tcx>,
+        flow_state: &Flows<'_, 'mir, 'tcx>,
         stmt: &'mir Statement<'tcx>,
         location: Location,
     ) {
@@ -683,7 +683,7 @@ impl<'mir, 'tcx, R> rustc_mir_dataflow::ResultsVisitor<'mir, 'tcx, R>
     fn visit_terminator_before_primary_effect(
         &mut self,
         _results: &mut R,
-        flow_state: &Flows<'mir, 'tcx>,
+        flow_state: &Flows<'_, 'mir, 'tcx>,
         term: &'mir Terminator<'tcx>,
         loc: Location,
     ) {
@@ -794,7 +794,7 @@ impl<'mir, 'tcx, R> rustc_mir_dataflow::ResultsVisitor<'mir, 'tcx, R>
     fn visit_terminator_after_primary_effect(
         &mut self,
         _results: &mut R,
-        flow_state: &Flows<'mir, 'tcx>,
+        flow_state: &Flows<'_, 'mir, 'tcx>,
         term: &'mir Terminator<'tcx>,
         loc: Location,
     ) {
@@ -988,7 +988,7 @@ impl<'mir, 'tcx> MirBorrowckCtxt<'_, 'mir, '_, 'tcx> {
         place_span: (Place<'tcx>, Span),
         kind: (AccessDepth, ReadOrWrite),
         is_local_mutation_allowed: LocalMutationIsAllowed,
-        flow_state: &Flows<'mir, 'tcx>,
+        flow_state: &Flows<'_, 'mir, 'tcx>,
     ) {
         let (sd, rw) = kind;
 
@@ -1038,7 +1038,7 @@ impl<'mir, 'tcx> MirBorrowckCtxt<'_, 'mir, '_, 'tcx> {
         place_span: (Place<'tcx>, Span),
         sd: AccessDepth,
         rw: ReadOrWrite,
-        flow_state: &Flows<'mir, 'tcx>,
+        flow_state: &Flows<'_, 'mir, 'tcx>,
     ) -> bool {
         let mut error_reported = false;
         let borrow_set = Rc::clone(&self.borrow_set);
@@ -1179,7 +1179,7 @@ impl<'mir, 'tcx> MirBorrowckCtxt<'_, 'mir, '_, 'tcx> {
         location: Location,
         place_span: (Place<'tcx>, Span),
         kind: AccessDepth,
-        flow_state: &Flows<'mir, 'tcx>,
+        flow_state: &Flows<'_, 'mir, 'tcx>,
     ) {
         // Write of P[i] or *P requires P init'd.
         self.check_if_assigned_path_is_moved(location, place_span, flow_state);
@@ -1197,7 +1197,7 @@ impl<'mir, 'tcx> MirBorrowckCtxt<'_, 'mir, '_, 'tcx> {
         &mut self,
         location: Location,
         (rvalue, span): (&'mir Rvalue<'tcx>, Span),
-        flow_state: &Flows<'mir, 'tcx>,
+        flow_state: &Flows<'_, 'mir, 'tcx>,
     ) {
         match rvalue {
             &Rvalue::Ref(_ /*rgn*/, bk, place) => {
@@ -1455,7 +1455,7 @@ impl<'mir, 'tcx> MirBorrowckCtxt<'_, 'mir, '_, 'tcx> {
         &mut self,
         location: Location,
         (operand, span): (&'mir Operand<'tcx>, Span),
-        flow_state: &Flows<'mir, 'tcx>,
+        flow_state: &Flows<'_, 'mir, 'tcx>,
     ) {
         match *operand {
             Operand::Copy(place) => {
@@ -1579,7 +1579,7 @@ impl<'mir, 'tcx> MirBorrowckCtxt<'_, 'mir, '_, 'tcx> {
         &mut self,
         location: Location,
         span: Span,
-        flow_state: &Flows<'mir, 'tcx>,
+        flow_state: &Flows<'_, 'mir, 'tcx>,
     ) {
         // Two-phase borrow support: For each activation that is newly
         // generated at this statement, check if it interferes with
@@ -1743,7 +1743,7 @@ impl<'mir, 'tcx> MirBorrowckCtxt<'_, 'mir, '_, 'tcx> {
         location: Location,
         desired_action: InitializationRequiringAction,
         place_span: (PlaceRef<'tcx>, Span),
-        flow_state: &Flows<'mir, 'tcx>,
+        flow_state: &Flows<'_, 'mir, 'tcx>,
     ) {
         let maybe_uninits = &flow_state.uninits;
 
@@ -1848,7 +1848,7 @@ impl<'mir, 'tcx> MirBorrowckCtxt<'_, 'mir, '_, 'tcx> {
         location: Location,
         desired_action: InitializationRequiringAction,
         place_span: (PlaceRef<'tcx>, Span),
-        flow_state: &Flows<'mir, 'tcx>,
+        flow_state: &Flows<'_, 'mir, 'tcx>,
     ) {
         let maybe_uninits = &flow_state.uninits;
 
@@ -1947,7 +1947,7 @@ impl<'mir, 'tcx> MirBorrowckCtxt<'_, 'mir, '_, 'tcx> {
         &mut self,
         location: Location,
         (place, span): (Place<'tcx>, Span),
-        flow_state: &Flows<'mir, 'tcx>,
+        flow_state: &Flows<'_, 'mir, 'tcx>,
     ) {
         debug!("check_if_assigned_path_is_moved place: {:?}", place);
 
@@ -2013,7 +2013,7 @@ impl<'mir, 'tcx> MirBorrowckCtxt<'_, 'mir, '_, 'tcx> {
             location: Location,
             base: PlaceRef<'tcx>,
             span: Span,
-            flow_state: &Flows<'mir, 'tcx>,
+            flow_state: &Flows<'_, 'mir, 'tcx>,
         ) {
             // rust-lang/rust#21232: Until Rust allows reads from the
             // initialized parts of partially initialized structs, we
@@ -2104,7 +2104,7 @@ impl<'mir, 'tcx> MirBorrowckCtxt<'_, 'mir, '_, 'tcx> {
         (place, span): (Place<'tcx>, Span),
         kind: ReadOrWrite,
         is_local_mutation_allowed: LocalMutationIsAllowed,
-        flow_state: &Flows<'mir, 'tcx>,
+        flow_state: &Flows<'_, 'mir, 'tcx>,
         location: Location,
     ) -> bool {
         debug!(
@@ -2220,7 +2220,7 @@ impl<'mir, 'tcx> MirBorrowckCtxt<'_, 'mir, '_, 'tcx> {
     fn is_local_ever_initialized(
         &self,
         local: Local,
-        flow_state: &Flows<'mir, 'tcx>,
+        flow_state: &Flows<'_, 'mir, 'tcx>,
     ) -> Option<InitIndex> {
         let mpi = self.move_data.rev_lookup.find_local(local)?;
         let ii = &self.move_data.init_path_map[mpi];
@@ -2228,7 +2228,7 @@ impl<'mir, 'tcx> MirBorrowckCtxt<'_, 'mir, '_, 'tcx> {
     }
 
     /// Adds the place into the used mutable variables set
-    fn add_used_mut(&mut self, root_place: RootPlace<'tcx>, flow_state: &Flows<'mir, 'tcx>) {
+    fn add_used_mut(&mut self, root_place: RootPlace<'tcx>, flow_state: &Flows<'_, 'mir, 'tcx>) {
         match root_place {
             RootPlace { place_local: local, place_projection: [], is_local_mutation_allowed } => {
                 // If the local may have been initialized, and it is now currently being
@@ -2428,12 +2428,12 @@ mod diags {
 
     use super::*;
 
-    enum BufferedDiag<'tcx> {
-        Error(Diag<'tcx>),
-        NonError(Diag<'tcx, ()>),
+    enum BufferedDiag<'infcx> {
+        Error(Diag<'infcx>),
+        NonError(Diag<'infcx, ()>),
     }
 
-    impl<'tcx> BufferedDiag<'tcx> {
+    impl<'infcx> BufferedDiag<'infcx> {
         fn sort_span(&self) -> Span {
             match self {
                 BufferedDiag::Error(diag) => diag.sort_span,
@@ -2442,7 +2442,7 @@ mod diags {
         }
     }
 
-    pub struct BorrowckDiags<'tcx> {
+    pub struct BorrowckDiags<'infcx, 'tcx> {
         /// This field keeps track of move errors that are to be reported for given move indices.
         ///
         /// There are situations where many errors can be reported for a single move out (see
@@ -2457,15 +2457,15 @@ mod diags {
         /// `BTreeMap` is used to preserve the order of insertions when iterating. This is necessary
         /// when errors in the map are being re-added to the error buffer so that errors with the
         /// same primary span come out in a consistent order.
-        buffered_move_errors: BTreeMap<Vec<MoveOutIndex>, (PlaceRef<'tcx>, Diag<'tcx>)>,
+        buffered_move_errors: BTreeMap<Vec<MoveOutIndex>, (PlaceRef<'tcx>, Diag<'infcx>)>,
 
-        buffered_mut_errors: FxIndexMap<Span, (Diag<'tcx>, usize)>,
+        buffered_mut_errors: FxIndexMap<Span, (Diag<'infcx>, usize)>,
 
         /// Buffer of diagnostics to be reported. A mixture of error and non-error diagnostics.
-        buffered_diags: Vec<BufferedDiag<'tcx>>,
+        buffered_diags: Vec<BufferedDiag<'infcx>>,
     }
 
-    impl<'tcx> BorrowckDiags<'tcx> {
+    impl<'infcx, 'tcx> BorrowckDiags<'infcx, 'tcx> {
         pub fn new() -> Self {
             BorrowckDiags {
                 buffered_move_errors: BTreeMap::new(),
@@ -2474,28 +2474,28 @@ mod diags {
             }
         }
 
-        pub fn buffer_error(&mut self, diag: Diag<'tcx>) {
+        pub fn buffer_error(&mut self, diag: Diag<'infcx>) {
             self.buffered_diags.push(BufferedDiag::Error(diag));
         }
 
-        pub fn buffer_non_error(&mut self, diag: Diag<'tcx, ()>) {
+        pub fn buffer_non_error(&mut self, diag: Diag<'infcx, ()>) {
             self.buffered_diags.push(BufferedDiag::NonError(diag));
         }
     }
 
-    impl<'tcx> MirBorrowckCtxt<'_, '_, '_, 'tcx> {
-        pub fn buffer_error(&mut self, diag: Diag<'tcx>) {
+    impl<'infcx, 'tcx> MirBorrowckCtxt<'_, '_, 'infcx, 'tcx> {
+        pub fn buffer_error(&mut self, diag: Diag<'infcx>) {
             self.diags.buffer_error(diag);
         }
 
-        pub fn buffer_non_error(&mut self, diag: Diag<'tcx, ()>) {
+        pub fn buffer_non_error(&mut self, diag: Diag<'infcx, ()>) {
             self.diags.buffer_non_error(diag);
         }
 
         pub fn buffer_move_error(
             &mut self,
             move_out_indices: Vec<MoveOutIndex>,
-            place_and_err: (PlaceRef<'tcx>, Diag<'tcx>),
+            place_and_err: (PlaceRef<'tcx>, Diag<'infcx>),
         ) -> bool {
             if let Some((_, diag)) =
                 self.diags.buffered_move_errors.insert(move_out_indices, place_and_err)
@@ -2508,12 +2508,12 @@ mod diags {
             }
         }
 
-        pub fn get_buffered_mut_error(&mut self, span: Span) -> Option<(Diag<'tcx>, usize)> {
+        pub fn get_buffered_mut_error(&mut self, span: Span) -> Option<(Diag<'infcx>, usize)> {
             // FIXME(#120456) - is `swap_remove` correct?
             self.diags.buffered_mut_errors.swap_remove(&span)
         }
 
-        pub fn buffer_mut_error(&mut self, span: Span, diag: Diag<'tcx>, count: usize) {
+        pub fn buffer_mut_error(&mut self, span: Span, diag: Diag<'infcx>, count: usize) {
             self.diags.buffered_mut_errors.insert(span, (diag, count));
         }
 
@@ -2554,7 +2554,7 @@ mod diags {
         pub fn has_move_error(
             &self,
             move_out_indices: &[MoveOutIndex],
-        ) -> Option<&(PlaceRef<'tcx>, Diag<'tcx>)> {
+        ) -> Option<&(PlaceRef<'tcx>, Diag<'infcx>)> {
             self.diags.buffered_move_errors.get(move_out_indices)
         }
     }
diff --git a/compiler/rustc_borrowck/src/nll.rs b/compiler/rustc_borrowck/src/nll.rs
index 923cf7e9405..2ffa9ba5b4d 100644
--- a/compiler/rustc_borrowck/src/nll.rs
+++ b/compiler/rustc_borrowck/src/nll.rs
@@ -81,7 +81,7 @@ pub(crate) fn compute_regions<'cx, 'tcx>(
     promoted: &IndexSlice<Promoted, Body<'tcx>>,
     location_table: &LocationTable,
     param_env: ty::ParamEnv<'tcx>,
-    flow_inits: &mut ResultsCursor<'cx, 'tcx, MaybeInitializedPlaces<'cx, 'tcx>>,
+    flow_inits: &mut ResultsCursor<'cx, 'tcx, MaybeInitializedPlaces<'_, 'cx, 'tcx>>,
     move_data: &MoveData<'tcx>,
     borrow_set: &BorrowSet<'tcx>,
     upvars: &[&ty::CapturedPlace<'tcx>],
@@ -262,13 +262,13 @@ pub(super) fn dump_mir_results<'tcx>(
 
 #[allow(rustc::diagnostic_outside_of_impl)]
 #[allow(rustc::untranslatable_diagnostic)]
-pub(super) fn dump_annotation<'tcx>(
-    infcx: &BorrowckInferCtxt<'tcx>,
+pub(super) fn dump_annotation<'tcx, 'cx>(
+    infcx: &'cx BorrowckInferCtxt<'tcx>,
     body: &Body<'tcx>,
     regioncx: &RegionInferenceContext<'tcx>,
     closure_region_requirements: &Option<ClosureRegionRequirements<'tcx>>,
     opaque_type_values: &FxIndexMap<LocalDefId, OpaqueHiddenType<'tcx>>,
-    diags: &mut crate::diags::BorrowckDiags<'tcx>,
+    diags: &mut crate::diags::BorrowckDiags<'cx, 'tcx>,
 ) {
     let tcx = infcx.tcx;
     let base_def_id = tcx.typeck_root_def_id(body.source.def_id());
@@ -285,7 +285,7 @@ pub(super) fn dump_annotation<'tcx>(
 
     let def_span = tcx.def_span(body.source.def_id());
     let mut err = if let Some(closure_region_requirements) = closure_region_requirements {
-        let mut err = tcx.dcx().struct_span_note(def_span, "external requirements");
+        let mut err = infcx.dcx().struct_span_note(def_span, "external requirements");
 
         regioncx.annotate(tcx, &mut err);
 
@@ -304,7 +304,7 @@ pub(super) fn dump_annotation<'tcx>(
 
         err
     } else {
-        let mut err = tcx.dcx().struct_span_note(def_span, "no external requirements");
+        let mut err = infcx.dcx().struct_span_note(def_span, "no external requirements");
         regioncx.annotate(tcx, &mut err);
 
         err
diff --git a/compiler/rustc_borrowck/src/region_infer/opaque_types.rs b/compiler/rustc_borrowck/src/region_infer/opaque_types.rs
index 67e5c8352df..e195ceded1b 100644
--- a/compiler/rustc_borrowck/src/region_infer/opaque_types.rs
+++ b/compiler/rustc_borrowck/src/region_infer/opaque_types.rs
@@ -285,7 +285,7 @@ impl<'tcx> InferCtxt<'tcx> {
         }
 
         if let Err(guar) =
-            check_opaque_type_parameter_valid(self.tcx, opaque_type_key, instantiated_ty.span)
+            check_opaque_type_parameter_valid(self, opaque_type_key, instantiated_ty.span)
         {
             return Ty::new_error(self.tcx, guar);
         }
@@ -294,6 +294,10 @@ impl<'tcx> InferCtxt<'tcx> {
             .remap_generic_params_to_declaration_params(opaque_type_key, self.tcx, false)
             .ty;
 
+        if let Err(e) = definition_ty.error_reported() {
+            return Ty::new_error(self.tcx, e);
+        }
+
         // `definition_ty` does not live in of the current inference context,
         // so lets make sure that we don't accidentally misuse our current `infcx`.
         match check_opaque_type_well_formed(
@@ -387,10 +391,11 @@ fn check_opaque_type_well_formed<'tcx>(
 /// [rustc-dev-guide chapter]:
 /// https://rustc-dev-guide.rust-lang.org/opaque-types-region-infer-restrictions.html
 fn check_opaque_type_parameter_valid<'tcx>(
-    tcx: TyCtxt<'tcx>,
+    infcx: &InferCtxt<'tcx>,
     opaque_type_key: OpaqueTypeKey<'tcx>,
     span: Span,
 ) -> Result<(), ErrorGuaranteed> {
+    let tcx = infcx.tcx;
     let opaque_generics = tcx.generics_of(opaque_type_key.def_id);
     let opaque_env = LazyOpaqueTyEnv::new(tcx, opaque_type_key.def_id);
     let mut seen_params: FxIndexMap<_, Vec<_>> = FxIndexMap::default();
@@ -420,7 +425,7 @@ fn check_opaque_type_parameter_valid<'tcx>(
 
             opaque_env.param_is_error(i)?;
 
-            return Err(tcx.dcx().emit_err(NonGenericOpaqueTypeParam {
+            return Err(infcx.dcx().emit_err(NonGenericOpaqueTypeParam {
                 ty: arg,
                 kind,
                 span,
@@ -438,7 +443,7 @@ fn check_opaque_type_parameter_valid<'tcx>(
                 .collect();
             #[allow(rustc::diagnostic_outside_of_impl)]
             #[allow(rustc::untranslatable_diagnostic)]
-            return Err(tcx
+            return Err(infcx
                 .dcx()
                 .struct_span_err(span, "non-defining opaque type use in defining scope")
                 .with_span_note(spans, format!("{descr} used multiple times"))
diff --git a/compiler/rustc_borrowck/src/type_check/liveness/mod.rs b/compiler/rustc_borrowck/src/type_check/liveness/mod.rs
index b777e01f7a6..6d6425b5f19 100644
--- a/compiler/rustc_borrowck/src/type_check/liveness/mod.rs
+++ b/compiler/rustc_borrowck/src/type_check/liveness/mod.rs
@@ -34,7 +34,7 @@ pub(super) fn generate<'mir, 'tcx>(
     typeck: &mut TypeChecker<'_, 'tcx>,
     body: &Body<'tcx>,
     elements: &Rc<DenseLocationMap>,
-    flow_inits: &mut ResultsCursor<'mir, 'tcx, MaybeInitializedPlaces<'mir, 'tcx>>,
+    flow_inits: &mut ResultsCursor<'mir, 'tcx, MaybeInitializedPlaces<'_, 'mir, 'tcx>>,
     move_data: &MoveData<'tcx>,
 ) {
     debug!("liveness::generate");
diff --git a/compiler/rustc_borrowck/src/type_check/liveness/trace.rs b/compiler/rustc_borrowck/src/type_check/liveness/trace.rs
index 359c4ea0eb1..eb86c8d06f1 100644
--- a/compiler/rustc_borrowck/src/type_check/liveness/trace.rs
+++ b/compiler/rustc_borrowck/src/type_check/liveness/trace.rs
@@ -43,7 +43,7 @@ pub(super) fn trace<'mir, 'tcx>(
     typeck: &mut TypeChecker<'_, 'tcx>,
     body: &Body<'tcx>,
     elements: &Rc<DenseLocationMap>,
-    flow_inits: &mut ResultsCursor<'mir, 'tcx, MaybeInitializedPlaces<'mir, 'tcx>>,
+    flow_inits: &mut ResultsCursor<'mir, 'tcx, MaybeInitializedPlaces<'_, 'mir, 'tcx>>,
     move_data: &MoveData<'tcx>,
     relevant_live_locals: Vec<Local>,
     boring_locals: Vec<Local>,
@@ -101,7 +101,7 @@ pub(super) fn trace<'mir, 'tcx>(
 }
 
 /// Contextual state for the type-liveness coroutine.
-struct LivenessContext<'me, 'typeck, 'flow, 'tcx> {
+struct LivenessContext<'a, 'me, 'typeck, 'flow, 'tcx> {
     /// Current type-checker, giving us our inference context etc.
     typeck: &'me mut TypeChecker<'typeck, 'tcx>,
 
@@ -119,7 +119,7 @@ struct LivenessContext<'me, 'typeck, 'flow, 'tcx> {
 
     /// Results of dataflow tracking which variables (and paths) have been
     /// initialized.
-    flow_inits: &'me mut ResultsCursor<'flow, 'tcx, MaybeInitializedPlaces<'flow, 'tcx>>,
+    flow_inits: &'me mut ResultsCursor<'flow, 'tcx, MaybeInitializedPlaces<'a, 'flow, 'tcx>>,
 
     /// Index indicating where each variable is assigned, used, or
     /// dropped.
@@ -131,8 +131,8 @@ struct DropData<'tcx> {
     region_constraint_data: Option<&'tcx QueryRegionConstraints<'tcx>>,
 }
 
-struct LivenessResults<'me, 'typeck, 'flow, 'tcx> {
-    cx: LivenessContext<'me, 'typeck, 'flow, 'tcx>,
+struct LivenessResults<'a, 'me, 'typeck, 'flow, 'tcx> {
+    cx: LivenessContext<'a, 'me, 'typeck, 'flow, 'tcx>,
 
     /// Set of points that define the current local.
     defs: BitSet<PointIndex>,
@@ -153,8 +153,8 @@ struct LivenessResults<'me, 'typeck, 'flow, 'tcx> {
     stack: Vec<PointIndex>,
 }
 
-impl<'me, 'typeck, 'flow, 'tcx> LivenessResults<'me, 'typeck, 'flow, 'tcx> {
-    fn new(cx: LivenessContext<'me, 'typeck, 'flow, 'tcx>) -> Self {
+impl<'a, 'me, 'typeck, 'flow, 'tcx> LivenessResults<'a, 'me, 'typeck, 'flow, 'tcx> {
+    fn new(cx: LivenessContext<'a, 'me, 'typeck, 'flow, 'tcx>) -> Self {
         let num_points = cx.elements.num_points();
         LivenessResults {
             cx,
@@ -507,7 +507,7 @@ impl<'me, 'typeck, 'flow, 'tcx> LivenessResults<'me, 'typeck, 'flow, 'tcx> {
     }
 }
 
-impl<'tcx> LivenessContext<'_, '_, '_, 'tcx> {
+impl<'tcx> LivenessContext<'_, '_, '_, '_, 'tcx> {
     /// Returns `true` if the local variable (or some part of it) is initialized at the current
     /// cursor position. Callers should call one of the `seek` methods immediately before to point
     /// the cursor to the desired location.
diff --git a/compiler/rustc_borrowck/src/type_check/mod.rs b/compiler/rustc_borrowck/src/type_check/mod.rs
index 81bde14a82f..aa25e3adf28 100644
--- a/compiler/rustc_borrowck/src/type_check/mod.rs
+++ b/compiler/rustc_borrowck/src/type_check/mod.rs
@@ -129,7 +129,7 @@ pub(crate) fn type_check<'mir, 'tcx>(
     location_table: &LocationTable,
     borrow_set: &BorrowSet<'tcx>,
     all_facts: &mut Option<AllFacts>,
-    flow_inits: &mut ResultsCursor<'mir, 'tcx, MaybeInitializedPlaces<'mir, 'tcx>>,
+    flow_inits: &mut ResultsCursor<'mir, 'tcx, MaybeInitializedPlaces<'_, 'mir, 'tcx>>,
     move_data: &MoveData<'tcx>,
     elements: &Rc<DenseLocationMap>,
     upvars: &[&ty::CapturedPlace<'tcx>],
diff --git a/compiler/rustc_borrowck/src/used_muts.rs b/compiler/rustc_borrowck/src/used_muts.rs
index 25e1f6268e0..e2de6b8b4a9 100644
--- a/compiler/rustc_borrowck/src/used_muts.rs
+++ b/compiler/rustc_borrowck/src/used_muts.rs
@@ -45,10 +45,10 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, '_, 'tcx> {
 
 /// MIR visitor for collecting used mutable variables.
 /// The 'visit lifetime represents the duration of the MIR walk.
-struct GatherUsedMutsVisitor<'visit, 'a, 'mir, 'cx, 'tcx> {
+struct GatherUsedMutsVisitor<'visit, 'a, 'mir, 'infcx, 'tcx> {
     temporary_used_locals: FxIndexSet<Local>,
     never_initialized_mut_locals: &'visit mut FxIndexSet<Local>,
-    mbcx: &'visit mut MirBorrowckCtxt<'a, 'mir, 'cx, 'tcx>,
+    mbcx: &'visit mut MirBorrowckCtxt<'a, 'mir, 'infcx, 'tcx>,
 }
 
 impl GatherUsedMutsVisitor<'_, '_, '_, '_, '_> {
diff --git a/compiler/rustc_codegen_cranelift/.github/workflows/abi-cafe.yml b/compiler/rustc_codegen_cranelift/.github/workflows/abi-cafe.yml
index b7063f35a3e..1ed6f8fc359 100644
--- a/compiler/rustc_codegen_cranelift/.github/workflows/abi-cafe.yml
+++ b/compiler/rustc_codegen_cranelift/.github/workflows/abi-cafe.yml
@@ -55,10 +55,6 @@ jobs:
       if: matrix.os == 'macos-latest' && matrix.env.TARGET_TRIPLE == 'x86_64-apple-darwin'
       run: rustup set default-host x86_64-apple-darwin
 
-    - name: Select XCode version
-      if: matrix.os == 'macos-latest'
-      run: sudo xcode-select -s /Applications/Xcode_14.3.1.app
-
     - name: Prepare dependencies
       run: ./y.sh prepare
 
diff --git a/compiler/rustc_codegen_cranelift/.github/workflows/main.yml b/compiler/rustc_codegen_cranelift/.github/workflows/main.yml
index 1f5a6513f63..a2ae3d63fb9 100644
--- a/compiler/rustc_codegen_cranelift/.github/workflows/main.yml
+++ b/compiler/rustc_codegen_cranelift/.github/workflows/main.yml
@@ -66,6 +66,9 @@ jobs:
             env:
               TARGET_TRIPLE: aarch64-unknown-linux-gnu
             apt_deps: gcc-aarch64-linux-gnu qemu-user
+          - os: macos-latest
+            env:
+              TARGET_TRIPLE: aarch64-apple-darwin
           - os: ubuntu-latest
             env:
               TARGET_TRIPLE: s390x-unknown-linux-gnu
@@ -108,10 +111,6 @@ jobs:
         sudo apt-get update
         sudo apt-get install -y ${{ matrix.apt_deps }}
 
-    - name: Select XCode version
-      if: matrix.os == 'macos-latest'
-      run: sudo xcode-select -s /Applications/Xcode_14.3.1.app
-
     - name: Prepare dependencies
       run: ./y.sh prepare
 
@@ -214,6 +213,9 @@ jobs:
           - os: macos-latest
             env:
               TARGET_TRIPLE: x86_64-apple-darwin
+          - os: macos-latest
+            env:
+              TARGET_TRIPLE: aarch64-apple-darwin
           # cross-compile from Linux to Windows using mingw
           - os: ubuntu-latest
             env:
@@ -248,10 +250,6 @@ jobs:
         sudo apt-get update
         sudo apt-get install -y gcc-mingw-w64-x86-64
 
-    - name: Select XCode version
-      if: matrix.os == 'macos-latest'
-      run: sudo xcode-select -s /Applications/Xcode_14.3.1.app
-
     - name: Prepare dependencies
       run: ./y.sh prepare
 
@@ -282,7 +280,8 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 10
     if: ${{ github.ref == 'refs/heads/master' }}
-    needs: [rustfmt, test, bench, dist]
+    # FIXME add the bench job back to the dependency list once rust-lang/rust#125493 gets merged
+    needs: [rustfmt, test, dist]
 
     permissions:
       contents: write # for creating the dev tag and release
diff --git a/compiler/rustc_codegen_cranelift/Cargo.lock b/compiler/rustc_codegen_cranelift/Cargo.lock
index 33fe52ddbdd..15c9e9d66fa 100644
--- a/compiler/rustc_codegen_cranelift/Cargo.lock
+++ b/compiler/rustc_codegen_cranelift/Cargo.lock
@@ -46,18 +46,18 @@ checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
 
 [[package]]
 name = "cranelift-bforest"
-version = "0.107.0"
+version = "0.109.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "79b27922a6879b5b5361d0a084cb0b1941bf109a98540addcb932da13b68bed4"
+checksum = "0b6b33d7e757a887989eb18b35712b2a67d96171ec3149d1bfb657b29b7b367c"
 dependencies = [
  "cranelift-entity",
 ]
 
 [[package]]
 name = "cranelift-codegen"
-version = "0.107.0"
+version = "0.109.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "304c455b28bf56372729acb356afbb55d622f2b0f2f7837aa5e57c138acaac4d"
+checksum = "b9acf15cb22be42d07c3b57d7856329cb228b7315d385346149df2566ad5e4aa"
 dependencies = [
  "bumpalo",
  "cranelift-bforest",
@@ -70,45 +70,46 @@ dependencies = [
  "hashbrown 0.14.3",
  "log",
  "regalloc2",
+ "rustc-hash",
  "smallvec",
  "target-lexicon",
 ]
 
 [[package]]
 name = "cranelift-codegen-meta"
-version = "0.107.0"
+version = "0.109.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1653c56b99591d07f67c5ca7f9f25888948af3f4b97186bff838d687d666f613"
+checksum = "e934d301392b73b3f8b0540391fb82465a0f179a3cee7c726482ac4727efcc97"
 dependencies = [
  "cranelift-codegen-shared",
 ]
 
 [[package]]
 name = "cranelift-codegen-shared"
-version = "0.107.0"
+version = "0.109.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f5b6a9cf6b6eb820ee3f973a0db313c05dc12d370f37b4fe9630286e1672573f"
+checksum = "8afb2a2566b3d54b854dfb288b3b187f6d3d17d6f762c92898207eba302931da"
 
 [[package]]
 name = "cranelift-control"
-version = "0.107.0"
+version = "0.109.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d9d06e6bf30075fb6bed9e034ec046475093392eea1aff90eb5c44c4a033d19a"
+checksum = "0100f33b704cdacd01ad66ff41f8c5030d57cbff078e2a4e49ab1822591299fa"
 dependencies = [
  "arbitrary",
 ]
 
 [[package]]
 name = "cranelift-entity"
-version = "0.107.0"
+version = "0.109.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "29be04f931b73cdb9694874a295027471817f26f26d2f0ebe5454153176b6e3a"
+checksum = "a8cfdc315e5d18997093e040a8d234bea1ac1e118a716d3e30f40d449e78207b"
 
 [[package]]
 name = "cranelift-frontend"
-version = "0.107.0"
+version = "0.109.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a07fd7393041d7faa2f37426f5dc7fc04003b70988810e8c063beefeff1cd8f9"
+checksum = "0f74b84f16af2e982b0c0c72233503d9d55cbfe3865dbe807ca28dc6642a28b5"
 dependencies = [
  "cranelift-codegen",
  "log",
@@ -118,15 +119,15 @@ dependencies = [
 
 [[package]]
 name = "cranelift-isle"
-version = "0.107.0"
+version = "0.109.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f341d7938caa6dff8149dac05bb2b53fc680323826b83b4cf175ab9f5139a3c9"
+checksum = "adf306d3dde705fb94bd48082f01d38c4ededc74293a4c007805f610bf08bc6e"
 
 [[package]]
 name = "cranelift-jit"
-version = "0.107.0"
+version = "0.109.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "42733555e06433f1461570e09dbd756dafc228b4dac75c597cdbdc518de07522"
+checksum = "f5c5cfb8bbd3339cd25cca30e7516ff8fe5cb1feeddde6980cc4d5ef34df97bb"
 dependencies = [
  "anyhow",
  "cranelift-codegen",
@@ -144,9 +145,9 @@ dependencies = [
 
 [[package]]
 name = "cranelift-module"
-version = "0.107.0"
+version = "0.109.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "84950af02bb85f3da764d53a953b43bb29a732e793d4fe24637a61591be9a024"
+checksum = "7c9b0d4269b36fd858e6d8f20cd4938941186fb831488c361888cb2d6b33a9a6"
 dependencies = [
  "anyhow",
  "cranelift-codegen",
@@ -155,9 +156,9 @@ dependencies = [
 
 [[package]]
 name = "cranelift-native"
-version = "0.107.0"
+version = "0.109.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "82af6066e6448d26eeabb7aa26a43f7ff79f8217b06bade4ee6ef230aecc8880"
+checksum = "1ea0ebdef7aff4a79bcbc8b6495f31315f16b3bf311152f472eaa8d679352581"
 dependencies = [
  "cranelift-codegen",
  "libc",
@@ -166,9 +167,9 @@ dependencies = [
 
 [[package]]
 name = "cranelift-object"
-version = "0.107.0"
+version = "0.109.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "00af56107039ed150391df6f753298c7b08f2b6a2e0727d216b5fa599d684d8b"
+checksum = "19e33439ec20db058bc7cc3410f9748ab1ad90a35cef713d625c736f43e3820d"
 dependencies = [
  "anyhow",
  "cranelift-codegen",
@@ -278,9 +279,9 @@ checksum = "6c8640c5d730cb13ebd907d8d04b52f55ac9a2eec55b440c8892f40d56c76c1d"
 
 [[package]]
 name = "object"
-version = "0.33.0"
+version = "0.36.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d8dd6c0cdf9429bce006e1362bfce61fa1bfd8c898a643ed8d2b471934701d3d"
+checksum = "081b846d1d56ddfc18fdf1a922e4f6e07a11768ea1b92dec44e42b72712ccfce"
 dependencies = [
  "crc32fast",
  "hashbrown 0.14.3",
@@ -410,10 +411,11 @@ checksum = "49874b5167b65d7193b8aba1567f5c7d93d001cafc34600cee003eda787e483f"
 
 [[package]]
 name = "wasmtime-jit-icache-coherence"
-version = "20.0.0"
+version = "22.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7a9f93a3289057b26dc75eb84d6e60d7694f7d169c7c09597495de6e016a13ff"
+checksum = "5afe2f0499542f9a4bcfa1b55bfdda803b6ade4e7c93c6b99e0f39dba44b0a91"
 dependencies = [
+ "anyhow",
  "cfg-if",
  "libc",
  "windows-sys",
diff --git a/compiler/rustc_codegen_cranelift/Cargo.toml b/compiler/rustc_codegen_cranelift/Cargo.toml
index 2015cdbcc2a..2969a6cf6ec 100644
--- a/compiler/rustc_codegen_cranelift/Cargo.toml
+++ b/compiler/rustc_codegen_cranelift/Cargo.toml
@@ -8,15 +8,15 @@ crate-type = ["dylib"]
 
 [dependencies]
 # These have to be in sync with each other
-cranelift-codegen = { version = "0.107.0", default-features = false, features = ["std", "unwind", "all-arch"] }
-cranelift-frontend = { version = "0.107.0" }
-cranelift-module = { version = "0.107.0" }
-cranelift-native = { version = "0.107.0" }
-cranelift-jit = { version = "0.107.0", optional = true }
-cranelift-object = { version = "0.107.0" }
+cranelift-codegen = { version = "0.109.0", default-features = false, features = ["std", "unwind", "all-arch"] }
+cranelift-frontend = { version = "0.109.0" }
+cranelift-module = { version = "0.109.0" }
+cranelift-native = { version = "0.109.0" }
+cranelift-jit = { version = "0.109.0", optional = true }
+cranelift-object = { version = "0.109.0" }
 target-lexicon = "0.12.0"
 gimli = { version = "0.28", default-features = false, features = ["write"]}
-object = { version = "0.33", default-features = false, features = ["std", "read_core", "write", "archive", "coff", "elf", "macho", "pe"] }
+object = { version = "0.36", default-features = false, features = ["std", "read_core", "write", "archive", "coff", "elf", "macho", "pe"] }
 
 indexmap = "2.0.0"
 libloading = { version = "0.8.0", optional = true }
diff --git a/compiler/rustc_codegen_cranelift/Readme.md b/compiler/rustc_codegen_cranelift/Readme.md
index 00ea15cb38c..eb21e027dd0 100644
--- a/compiler/rustc_codegen_cranelift/Readme.md
+++ b/compiler/rustc_codegen_cranelift/Readme.md
@@ -70,7 +70,7 @@ For more docs on how to build and test see [build_system/usage.txt](build_system
 |FreeBSD|✅[^no-rustup]|❓|❓|❓|
 |AIX|❌[^xcoff]|N/A|N/A|❌[^xcoff]|
 |Other unixes|❓|❓|❓|❓|
-|macOS|✅|❌[^apple-silicon]|N/A|N/A|
+|macOS|✅|✅[^no-rustup]|N/A|N/A|
 |Windows|✅[^no-rustup]|❌|N/A|N/A|
 
 ✅: Fully supported and tested
@@ -80,7 +80,6 @@ For more docs on how to build and test see [build_system/usage.txt](build_system
 Not all targets are available as rustup component for nightly. See notes in the platform support matrix.
 
 [^xcoff]: XCOFF object file format is not supported.
-[^apple-silicon]: Tracked in [#1248](https://github.com/rust-lang/rustc_codegen_cranelift/issues/1248).
 [^no-rustup]: Not available as rustup component for nightly. You can build it yourself.
 
 ## Usage
diff --git a/compiler/rustc_codegen_cranelift/build_system/build_sysroot.rs b/compiler/rustc_codegen_cranelift/build_system/build_sysroot.rs
index 196ff8fda75..dfbe0f51e7b 100644
--- a/compiler/rustc_codegen_cranelift/build_system/build_sysroot.rs
+++ b/compiler/rustc_codegen_cranelift/build_system/build_sysroot.rs
@@ -267,10 +267,6 @@ fn build_clif_sysroot_for_triple(
             prefix.to_str().unwrap()
         ));
     }
-    rustflags.push("-Zunstable-options".to_owned());
-    for (name, values) in EXTRA_CHECK_CFGS {
-        rustflags.push(check_cfg_arg(name, *values));
-    }
     compiler.rustflags.extend(rustflags);
     let mut build_cmd = STANDARD_LIBRARY.build(&compiler, dirs);
     if channel == "release" {
@@ -330,34 +326,3 @@ fn build_rtstartup(dirs: &Dirs, compiler: &Compiler) -> Option<SysrootTarget> {
 
     Some(target_libs)
 }
-
-// Copied from https://github.com/rust-lang/rust/blob/4fd98a4b1b100f5329c6efae18031791f64372d2/src/bootstrap/src/utils/helpers.rs#L569-L585
-/// Create a `--check-cfg` argument invocation for a given name
-/// and it's values.
-fn check_cfg_arg(name: &str, values: Option<&[&str]>) -> String {
-    // Creating a string of the values by concatenating each value:
-    // ',values("tvos","watchos")' or '' (nothing) when there are no values.
-    let next = match values {
-        Some(values) => {
-            let mut tmp = values.iter().flat_map(|val| [",", "\"", val, "\""]).collect::<String>();
-
-            tmp.insert_str(1, "values(");
-            tmp.push(')');
-            tmp
-        }
-        None => "".to_string(),
-    };
-    format!("--check-cfg=cfg({name}{next})")
-}
-
-const EXTRA_CHECK_CFGS: &[(&str, Option<&[&str]>)] = &[
-    ("bootstrap", None),
-    ("stdarch_intel_sde", None),
-    ("no_fp_fmt_parse", None),
-    ("no_global_oom_handling", None),
-    ("no_rc", None),
-    ("no_sync", None),
-    ("netbsd10", None),
-    ("backtrace_in_libstd", None),
-    ("target_arch", Some(&["xtensa"])),
-];
diff --git a/compiler/rustc_codegen_cranelift/build_system/tests.rs b/compiler/rustc_codegen_cranelift/build_system/tests.rs
index 278f334796a..790d9cbd9fc 100644
--- a/compiler/rustc_codegen_cranelift/build_system/tests.rs
+++ b/compiler/rustc_codegen_cranelift/build_system/tests.rs
@@ -329,7 +329,6 @@ pub(crate) fn run_tests(
 struct TestRunner<'a> {
     is_native: bool,
     jit_supported: bool,
-    use_unstable_features: bool,
     skip_tests: &'a [&'a str],
     dirs: Dirs,
     target_compiler: Compiler,
@@ -361,15 +360,7 @@ impl<'a> TestRunner<'a> {
             && target_compiler.triple.contains("x86_64")
             && !target_compiler.triple.contains("windows");
 
-        Self {
-            is_native,
-            jit_supported,
-            use_unstable_features,
-            skip_tests,
-            dirs,
-            target_compiler,
-            stdlib_source,
-        }
+        Self { is_native, jit_supported, skip_tests, dirs, target_compiler, stdlib_source }
     }
 
     fn run_testsuite(&self, tests: &[TestCase]) {
@@ -393,31 +384,13 @@ impl<'a> TestRunner<'a> {
             match *cmd {
                 TestCaseCmd::Custom { func } => func(self),
                 TestCaseCmd::BuildLib { source, crate_types } => {
-                    if self.use_unstable_features {
-                        self.run_rustc([source, "--crate-type", crate_types]);
-                    } else {
-                        self.run_rustc([
-                            source,
-                            "--crate-type",
-                            crate_types,
-                            "--cfg",
-                            "no_unstable_features",
-                        ]);
-                    }
+                    self.run_rustc([source, "--crate-type", crate_types]);
                 }
                 TestCaseCmd::BuildBin { source } => {
-                    if self.use_unstable_features {
-                        self.run_rustc([source]);
-                    } else {
-                        self.run_rustc([source, "--cfg", "no_unstable_features"]);
-                    }
+                    self.run_rustc([source]);
                 }
                 TestCaseCmd::BuildBinAndRun { source, args } => {
-                    if self.use_unstable_features {
-                        self.run_rustc([source]);
-                    } else {
-                        self.run_rustc([source, "--cfg", "no_unstable_features"]);
-                    }
+                    self.run_rustc([source]);
                     self.run_out_command(
                         source.split('/').last().unwrap().split('.').next().unwrap(),
                         args,
@@ -472,7 +445,6 @@ impl<'a> TestRunner<'a> {
         cmd.arg(&self.target_compiler.triple);
         cmd.arg("-Cpanic=abort");
         cmd.arg("-Zunstable-options");
-        cmd.arg("--check-cfg=cfg(no_unstable_features)");
         cmd.arg("--check-cfg=cfg(jit)");
         cmd.args(args);
         cmd
diff --git a/compiler/rustc_codegen_cranelift/example/mini_core_hello_world.rs b/compiler/rustc_codegen_cranelift/example/mini_core_hello_world.rs
index aab20f67248..7d361a9ab2b 100644
--- a/compiler/rustc_codegen_cranelift/example/mini_core_hello_world.rs
+++ b/compiler/rustc_codegen_cranelift/example/mini_core_hello_world.rs
@@ -333,12 +333,7 @@ fn main() {
     #[cfg(all(not(jit), not(all(windows, target_env = "gnu"))))]
     test_tls();
 
-    #[cfg(all(
-        not(jit),
-        not(no_unstable_features),
-        target_arch = "x86_64",
-        any(target_os = "linux", target_os = "macos")
-    ))]
+    #[cfg(all(not(jit), target_arch = "x86_64", any(target_os = "linux", target_os = "macos")))]
     unsafe {
         global_asm_test();
         naked_test();
@@ -367,17 +362,12 @@ fn stack_val_align() {
     assert_eq!(&a as *const Foo as usize % 8192, 0);
 }
 
-#[cfg(all(
-    not(jit),
-    not(no_unstable_features),
-    target_arch = "x86_64",
-    any(target_os = "linux", target_os = "macos")
-))]
+#[cfg(all(not(jit), target_arch = "x86_64", any(target_os = "linux", target_os = "macos")))]
 extern "C" {
     fn global_asm_test();
 }
 
-#[cfg(all(not(jit), not(no_unstable_features), target_arch = "x86_64", target_os = "linux"))]
+#[cfg(all(not(jit), target_arch = "x86_64", target_os = "linux"))]
 global_asm! {
     "
     .global global_asm_test
@@ -387,7 +377,7 @@ global_asm! {
     "
 }
 
-#[cfg(all(not(jit), not(no_unstable_features), target_arch = "x86_64", target_os = "macos"))]
+#[cfg(all(not(jit), target_arch = "x86_64", target_os = "macos"))]
 global_asm! {
     "
     .global _global_asm_test
@@ -397,7 +387,7 @@ global_asm! {
     "
 }
 
-#[cfg(all(not(jit), not(no_unstable_features), target_arch = "x86_64"))]
+#[cfg(all(not(jit), target_arch = "x86_64"))]
 #[naked]
 extern "C" fn naked_test() {
     unsafe {
diff --git a/compiler/rustc_codegen_cranelift/example/std_example.rs b/compiler/rustc_codegen_cranelift/example/std_example.rs
index 7347b2e7789..6cedd84adfe 100644
--- a/compiler/rustc_codegen_cranelift/example/std_example.rs
+++ b/compiler/rustc_codegen_cranelift/example/std_example.rs
@@ -251,6 +251,9 @@ unsafe fn test_simd() {
     test_mm_add_epi8();
     test_mm_add_pd();
     test_mm_cvtepi8_epi16();
+    #[cfg(not(jit))]
+    test_mm_cvtps_epi32();
+    test_mm_cvttps_epi32();
     test_mm_cvtsi128_si64();
 
     test_mm_extract_epi8();
@@ -476,6 +479,41 @@ unsafe fn test_mm256_permutevar8x32_epi32() {
     assert_eq_m256i(r, e);
 }
 
+#[cfg(target_arch = "x86_64")]
+#[target_feature(enable = "avx2")]
+#[cfg(not(jit))]
+unsafe fn test_mm_cvtps_epi32() {
+    let floats: [f32; 4] = [1.5, -2.5, i32::MAX as f32 + 1.0, f32::NAN];
+
+    let float_vec = _mm_loadu_ps(floats.as_ptr());
+    let int_vec = _mm_cvtps_epi32(float_vec);
+
+    let mut ints: [i32; 4] = [0; 4];
+    _mm_storeu_si128(ints.as_mut_ptr() as *mut __m128i, int_vec);
+
+    // this is very different from `floats.map(|f| f as i32)`!
+    let expected_ints: [i32; 4] = [2, -2, i32::MIN, i32::MIN];
+
+    assert_eq!(ints, expected_ints);
+}
+
+#[cfg(target_arch = "x86_64")]
+#[target_feature(enable = "avx2")]
+unsafe fn test_mm_cvttps_epi32() {
+    let floats: [f32; 4] = [1.5, -2.5, i32::MAX as f32 + 1.0, f32::NAN];
+
+    let float_vec = _mm_loadu_ps(floats.as_ptr());
+    let int_vec = _mm_cvttps_epi32(float_vec);
+
+    let mut ints: [i32; 4] = [0; 4];
+    _mm_storeu_si128(ints.as_mut_ptr() as *mut __m128i, int_vec);
+
+    // this is very different from `floats.map(|f| f as i32)`!
+    let expected_ints: [i32; 4] = [1, -2, i32::MIN, i32::MIN];
+
+    assert_eq!(ints, expected_ints);
+}
+
 fn test_checked_mul() {
     let u: Option<u8> = u8::from_str_radix("1000", 10).ok();
     assert_eq!(u, None);
diff --git a/compiler/rustc_codegen_cranelift/patches/stdlib-lock.toml b/compiler/rustc_codegen_cranelift/patches/stdlib-lock.toml
index c8c7b45bc9a..9ea53e8f848 100644
--- a/compiler/rustc_codegen_cranelift/patches/stdlib-lock.toml
+++ b/compiler/rustc_codegen_cranelift/patches/stdlib-lock.toml
@@ -4,12 +4,12 @@ version = 3
 
 [[package]]
 name = "addr2line"
-version = "0.21.0"
+version = "0.22.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8a30b2e23b9e17a9f90641c7ab1549cd9b44f296d3ccbf309d2863cfe398a0cb"
+checksum = "6e4503c46a5c0c7844e948c9a4d6acd9f50cccb4de1c48eb9e291ea17470c678"
 dependencies = [
  "compiler_builtins",
- "gimli",
+ "gimli 0.29.0",
  "rustc-std-workspace-alloc",
  "rustc-std-workspace-core",
 ]
@@ -134,6 +134,17 @@ dependencies = [
 ]
 
 [[package]]
+name = "gimli"
+version = "0.29.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "40ecd4077b5ae9fd2e9e169b102c6c330d0605168eb0e8bf79952b256dbefffd"
+dependencies = [
+ "compiler_builtins",
+ "rustc-std-workspace-alloc",
+ "rustc-std-workspace-core",
+]
+
+[[package]]
 name = "hashbrown"
 version = "0.14.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -147,9 +158,9 @@ dependencies = [
 
 [[package]]
 name = "hermit-abi"
-version = "0.3.9"
+version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d231dfb89cfffdbc30e7fc41579ed6066ad03abda9e567ccafae602b97ec5024"
+checksum = "fbf6a919d6cf397374f7dfeeea91d974c7c0a7221d0d0f4f20d859d329e53fcc"
 dependencies = [
  "compiler_builtins",
  "rustc-std-workspace-alloc",
@@ -189,9 +200,9 @@ dependencies = [
 
 [[package]]
 name = "object"
-version = "0.32.1"
+version = "0.36.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9cf5f9dd3933bd50a9e1f149ec995f39ae2c496d31fd772c1fd45ebc27e902b0"
+checksum = "576dfe1fc8f9df304abb159d767a29d0476f7750fbf8aa7ad07816004a207434"
 dependencies = [
  "compiler_builtins",
  "memchr",
@@ -286,9 +297,9 @@ dependencies = [
 
 [[package]]
 name = "rustc-demangle"
-version = "0.1.23"
+version = "0.1.24"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d626bb9dae77e28219937af045c257c28bfd3f69333c512553507f5f9798cb76"
+checksum = "719b953e2095829ee67db738b3bfa9fa368c94900df327b3f07fe6e794d2fe1f"
 dependencies = [
  "compiler_builtins",
  "rustc-std-workspace-core",
@@ -396,8 +407,6 @@ dependencies = [
  "core",
  "getopts",
  "libc",
- "panic_abort",
- "panic_unwind",
  "std",
 ]
 
@@ -430,7 +439,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "37a19a21a537f635c16c7576f22d0f2f7d63353c1337ad4ce0d8001c7952a25b"
 dependencies = [
  "compiler_builtins",
- "gimli",
+ "gimli 0.28.1",
  "rustc-std-workspace-core",
 ]
 
diff --git a/compiler/rustc_codegen_cranelift/rust-toolchain b/compiler/rustc_codegen_cranelift/rust-toolchain
index a2ba79cbe90..cfa91744a0e 100644
--- a/compiler/rustc_codegen_cranelift/rust-toolchain
+++ b/compiler/rustc_codegen_cranelift/rust-toolchain
@@ -1,3 +1,3 @@
 [toolchain]
-channel = "nightly-2024-05-13"
+channel = "nightly-2024-06-30"
 components = ["rust-src", "rustc-dev", "llvm-tools"]
diff --git a/compiler/rustc_codegen_cranelift/scripts/test_rustc_tests.sh b/compiler/rustc_codegen_cranelift/scripts/test_rustc_tests.sh
index 689cda21643..c1b7e4b0e07 100755
--- a/compiler/rustc_codegen_cranelift/scripts/test_rustc_tests.sh
+++ b/compiler/rustc_codegen_cranelift/scripts/test_rustc_tests.sh
@@ -36,9 +36,8 @@ rm tests/ui/parser/unclosed-delimiter-in-dep.rs # submodule contains //~ERROR
 rm tests/ui/asm/x86_64/evex512-implicit-feature.rs # unimplemented AVX512 x86 vendor intrinsic
 
 # exotic linkages
-rm tests/ui/issues/issue-33992.rs # unsupported linkages
-rm tests/incremental/hashes/function_interfaces.rs # same
-rm tests/incremental/hashes/statics.rs # same
+rm tests/incremental/hashes/function_interfaces.rs
+rm tests/incremental/hashes/statics.rs
 
 # variadic arguments
 rm tests/ui/abi/mir/mir_codegen_calls_variadic.rs # requires float varargs
@@ -60,13 +59,20 @@ rm tests/ui/asm/x86_64/goto.rs # inline asm labels not supported
 
 # requires LTO
 rm -r tests/run-make/cdylib
-rm -r tests/run-make/issue-14500
-rm -r tests/run-make/issue-64153
 rm -r tests/run-make/codegen-options-parsing
 rm -r tests/run-make/lto-*
 rm -r tests/run-make/reproducible-build-2
 rm -r tests/run-make/issue-109934-lto-debuginfo
 rm -r tests/run-make/no-builtins-lto
+rm -r tests/run-make/reachable-extern-fn-available-lto
+
+# coverage instrumentation
+rm tests/ui/consts/precise-drop-with-coverage.rs
+rm tests/ui/issues/issue-85461.rs
+rm -r tests/ui/instrument-coverage/
+
+# missing f16/f128 support
+rm tests/ui/half-open-range-patterns/half-open-range-pats-semantics.rs
 
 # optimization tests
 # ==================
@@ -74,6 +80,7 @@ rm tests/ui/codegen/issue-28950.rs # depends on stack size optimizations
 rm tests/ui/codegen/init-large-type.rs # same
 rm tests/ui/issues/issue-40883.rs # same
 rm -r tests/run-make/fmt-write-bloat/ # tests an optimization
+rm tests/ui/statics/const_generics.rs # same
 
 # backend specific tests
 # ======================
@@ -85,6 +92,7 @@ rm -r tests/run-make/sepcomp-cci-copies # same
 rm -r tests/run-make/volatile-intrinsics # same
 rm -r tests/run-make/llvm-ident # same
 rm -r tests/run-make/no-builtins-attribute # same
+rm -r tests/run-make/pgo-gen-no-imp-symbols # same
 rm tests/ui/abi/stack-protector.rs # requires stack protector support
 rm -r tests/run-make/emit-stack-sizes # requires support for -Z emit-stack-sizes
 rm -r tests/run-make/optimization-remarks-dir # remarks are LLVM specific
@@ -93,13 +101,14 @@ rm -r tests/run-make/print-to-output # requires --print relocation-models
 # requires asm, llvm-ir and/or llvm-bc emit support
 # =============================================
 rm -r tests/run-make/emit-named-files
-rm -r tests/run-make/issue-30063
 rm -r tests/run-make/multiple-emits
 rm -r tests/run-make/output-type-permutations
 rm -r tests/run-make/emit-to-stdout
 rm -r tests/run-make/compressed-debuginfo
 rm -r tests/run-make/symbols-include-type-name
-
+rm -r tests/run-make/notify-all-emit-artifacts
+rm -r tests/run-make/reset-codegen-1
+rm -r tests/run-make/inline-always-many-cgu
 
 # giving different but possibly correct results
 # =============================================
@@ -118,6 +127,7 @@ rm -r tests/run-make/compiler-builtins # Expects lib/rustlib/src/rust to contain
 # ============
 rm -r tests/run-make/extern-fn-explicit-align # argument alignment not yet supported
 rm -r tests/run-make/panic-abort-eh_frame # .eh_frame emitted with panic=abort
+rm tests/ui/deprecation/deprecated_inline_threshold.rs # missing deprecation warning for -Cinline-threshold
 
 # bugs in the test suite
 # ======================
@@ -148,12 +158,12 @@ index 9607ff02f96..b7d97caf9a2 100644
 --- a/src/tools/run-make-support/src/rustdoc.rs
 +++ b/src/tools/run-make-support/src/rustdoc.rs
 @@ -34,8 +34,6 @@ pub fn bare() -> Self {
-     /// Construct a \`rustdoc\` invocation with \`-L \$(TARGET_RPATH_DIR)\` set.
+     #[track_caller]
      pub fn new() -> Self {
          let mut cmd = setup_common();
--        let target_rpath_dir = env::var_os("TARGET_RPATH_DIR").unwrap();
+-        let target_rpath_dir = env_var_os("TARGET_RPATH_DIR");
 -        cmd.arg(format!("-L{}", target_rpath_dir.to_string_lossy()));
-         Self { cmd, stdin: None }
+         Self { cmd }
      }
 
 EOF
diff --git a/compiler/rustc_codegen_cranelift/src/abi/mod.rs b/compiler/rustc_codegen_cranelift/src/abi/mod.rs
index 695dbaf2804..0d7eee7afb4 100644
--- a/compiler/rustc_codegen_cranelift/src/abi/mod.rs
+++ b/compiler/rustc_codegen_cranelift/src/abi/mod.rs
@@ -5,8 +5,9 @@ mod pass_mode;
 mod returning;
 
 use std::borrow::Cow;
+use std::mem;
 
-use cranelift_codegen::ir::SigRef;
+use cranelift_codegen::ir::{ArgumentPurpose, SigRef};
 use cranelift_codegen::isa::CallConv;
 use cranelift_module::ModuleError;
 use rustc_codegen_ssa::errors::CompilerBuiltinsCannotCall;
@@ -17,7 +18,7 @@ use rustc_middle::ty::TypeVisitableExt;
 use rustc_monomorphize::is_call_from_compiler_builtins_to_upstream_monomorphization;
 use rustc_session::Session;
 use rustc_span::source_map::Spanned;
-use rustc_target::abi::call::{Conv, FnAbi};
+use rustc_target::abi::call::{Conv, FnAbi, PassMode};
 use rustc_target::spec::abi::Abi;
 
 use self::pass_mode::*;
@@ -487,6 +488,7 @@ pub(crate) fn codegen_terminator_call<'tcx>(
     let args = args;
     assert_eq!(fn_abi.args.len(), args.len());
 
+    #[derive(Copy, Clone)]
     enum CallTarget {
         Direct(FuncRef),
         Indirect(SigRef, Value),
@@ -532,7 +534,7 @@ pub(crate) fn codegen_terminator_call<'tcx>(
     };
 
     self::returning::codegen_with_call_return_arg(fx, &fn_abi.ret, ret_place, |fx, return_ptr| {
-        let call_args = return_ptr
+        let mut call_args = return_ptr
             .into_iter()
             .chain(first_arg_override.into_iter())
             .chain(
@@ -545,47 +547,118 @@ pub(crate) fn codegen_terminator_call<'tcx>(
             )
             .collect::<Vec<Value>>();
 
-        let call_inst = match func_ref {
+        // FIXME: Find a cleaner way to support varargs.
+        if fn_abi.c_variadic {
+            adjust_call_for_c_variadic(fx, &fn_abi, source_info, func_ref, &mut call_args);
+        }
+
+        match func_ref {
             CallTarget::Direct(func_ref) => fx.bcx.ins().call(func_ref, &call_args),
             CallTarget::Indirect(sig, func_ptr) => {
                 fx.bcx.ins().call_indirect(sig, func_ptr, &call_args)
             }
+        }
+    });
+
+    if let Some(dest) = target {
+        let ret_block = fx.get_block(dest);
+        fx.bcx.ins().jump(ret_block, &[]);
+    } else {
+        fx.bcx.ins().trap(TrapCode::UnreachableCodeReached);
+    }
+
+    fn adjust_call_for_c_variadic<'tcx>(
+        fx: &mut FunctionCx<'_, '_, 'tcx>,
+        fn_abi: &FnAbi<'tcx, Ty<'tcx>>,
+        source_info: mir::SourceInfo,
+        target: CallTarget,
+        call_args: &mut Vec<Value>,
+    ) {
+        if fn_abi.conv != Conv::C {
+            fx.tcx.dcx().span_fatal(
+                source_info.span,
+                format!("Variadic call for non-C abi {:?}", fn_abi.conv),
+            );
+        }
+        let sig_ref = match target {
+            CallTarget::Direct(func_ref) => fx.bcx.func.dfg.ext_funcs[func_ref].signature,
+            CallTarget::Indirect(sig_ref, _) => sig_ref,
         };
+        // `mem::take()` the `params` so that `fx.bcx` can be used below.
+        let mut abi_params = mem::take(&mut fx.bcx.func.dfg.signatures[sig_ref].params);
+
+        // Recalculate the parameters in the signature to ensure the signature contains the variadic arguments.
+        let has_return_arg = matches!(fn_abi.ret.mode, PassMode::Indirect { .. });
+        // Drop everything except the return argument (if there is one).
+        abi_params.truncate(if has_return_arg { 1 } else { 0 });
+        // Add the fixed arguments.
+        abi_params.extend(
+            fn_abi.args[..fn_abi.fixed_count as usize]
+                .iter()
+                .flat_map(|arg_abi| arg_abi.get_abi_param(fx.tcx).into_iter()),
+        );
+        let fixed_arg_count = abi_params.len();
+        // Add the variadic arguments.
+        abi_params.extend(
+            fn_abi.args[fn_abi.fixed_count as usize..]
+                .iter()
+                .flat_map(|arg_abi| arg_abi.get_abi_param(fx.tcx).into_iter()),
+        );
 
-        // FIXME find a cleaner way to support varargs
-        if fn_sig.c_variadic() {
-            if !matches!(fn_sig.abi(), Abi::C { .. }) {
+        if fx.tcx.sess.target.is_like_osx && fx.tcx.sess.target.arch == "aarch64" {
+            // Add any padding arguments needed for Apple AArch64.
+            // There's no need to pad the argument list unless variadic arguments are actually being
+            // passed.
+            if abi_params.len() > fixed_arg_count {
+                // 128-bit integers take 2 registers, and everything else takes 1.
+                // FIXME: Add support for non-integer types
+                // This relies on the checks below to ensure all arguments are integer types and
+                // that the ABI is "C".
+                // The return argument isn't counted as it goes in its own dedicated register.
+                let integer_registers_used: usize = abi_params
+                    [if has_return_arg { 1 } else { 0 }..fixed_arg_count]
+                    .iter()
+                    .map(|arg| if arg.value_type.bits() == 128 { 2 } else { 1 })
+                    .sum();
+                // The ABI uses 8 registers before it starts pushing arguments to the stack. Pad out
+                // the registers if needed to ensure the variadic arguments are passed on the stack.
+                if integer_registers_used < 8 {
+                    abi_params.splice(
+                        fixed_arg_count..fixed_arg_count,
+                        (integer_registers_used..8).map(|_| AbiParam::new(types::I64)),
+                    );
+                    call_args.splice(
+                        fixed_arg_count..fixed_arg_count,
+                        (integer_registers_used..8).map(|_| fx.bcx.ins().iconst(types::I64, 0)),
+                    );
+                }
+            }
+
+            // `StructArgument` is not currently used by the `aarch64` ABI, and is therefore not
+            // handled when calculating how many padding arguments to use. Assert that this remains
+            // the case.
+            assert!(abi_params.iter().all(|param| matches!(
+                param.purpose,
+                // The only purposes used are `Normal` and `StructReturn`.
+                ArgumentPurpose::Normal | ArgumentPurpose::StructReturn
+            )));
+        }
+
+        // Check all parameters are integers.
+        for param in abi_params.iter() {
+            if !param.value_type.is_int() {
+                // FIXME: Set %al to upperbound on float args once floats are supported.
                 fx.tcx.dcx().span_fatal(
                     source_info.span,
-                    format!("Variadic call for non-C abi {:?}", fn_sig.abi()),
+                    format!("Non int ty {:?} for variadic call", param.value_type),
                 );
             }
-            let sig_ref = fx.bcx.func.dfg.call_signature(call_inst).unwrap();
-            let abi_params = call_args
-                .into_iter()
-                .map(|arg| {
-                    let ty = fx.bcx.func.dfg.value_type(arg);
-                    if !ty.is_int() {
-                        // FIXME set %al to upperbound on float args once floats are supported
-                        fx.tcx.dcx().span_fatal(
-                            source_info.span,
-                            format!("Non int ty {:?} for variadic call", ty),
-                        );
-                    }
-                    AbiParam::new(ty)
-                })
-                .collect::<Vec<AbiParam>>();
-            fx.bcx.func.dfg.signatures[sig_ref].params = abi_params;
         }
 
-        call_inst
-    });
+        assert_eq!(abi_params.len(), call_args.len());
 
-    if let Some(dest) = target {
-        let ret_block = fx.get_block(dest);
-        fx.bcx.ins().jump(ret_block, &[]);
-    } else {
-        fx.bcx.ins().trap(TrapCode::UnreachableCodeReached);
+        // Put the `AbiParam`s back in the signature.
+        fx.bcx.func.dfg.signatures[sig_ref].params = abi_params;
     }
 }
 
diff --git a/compiler/rustc_codegen_cranelift/src/allocator.rs b/compiler/rustc_codegen_cranelift/src/allocator.rs
index e8af3e8c255..b4a3825e996 100644
--- a/compiler/rustc_codegen_cranelift/src/allocator.rs
+++ b/compiler/rustc_codegen_cranelift/src/allocator.rs
@@ -11,15 +11,10 @@ use rustc_session::config::OomStrategy;
 use crate::prelude::*;
 
 /// Returns whether an allocator shim was created
-pub(crate) fn codegen(
-    tcx: TyCtxt<'_>,
-    module: &mut impl Module,
-    unwind_context: &mut UnwindContext,
-) -> bool {
+pub(crate) fn codegen(tcx: TyCtxt<'_>, module: &mut dyn Module) -> bool {
     let Some(kind) = allocator_kind_for_codegen(tcx) else { return false };
     codegen_inner(
         module,
-        unwind_context,
         kind,
         tcx.alloc_error_handler_kind(()).unwrap(),
         tcx.sess.opts.unstable_opts.oom,
@@ -28,8 +23,7 @@ pub(crate) fn codegen(
 }
 
 fn codegen_inner(
-    module: &mut impl Module,
-    unwind_context: &mut UnwindContext,
+    module: &mut dyn Module,
     kind: AllocatorKind,
     alloc_error_handler_kind: AllocatorKind,
     oom_strategy: OomStrategy,
@@ -67,7 +61,6 @@ fn codegen_inner(
             };
             crate::common::create_wrapper_function(
                 module,
-                unwind_context,
                 sig,
                 &global_fn_name(method.name),
                 &default_fn_name(method.name),
@@ -82,7 +75,6 @@ fn codegen_inner(
     };
     crate::common::create_wrapper_function(
         module,
-        unwind_context,
         sig,
         "__rust_alloc_error_handler",
         &alloc_error_handler_name(alloc_error_handler_kind),
diff --git a/compiler/rustc_codegen_cranelift/src/base.rs b/compiler/rustc_codegen_cranelift/src/base.rs
index b117dc496c2..c5b4277015a 100644
--- a/compiler/rustc_codegen_cranelift/src/base.rs
+++ b/compiler/rustc_codegen_cranelift/src/base.rs
@@ -249,9 +249,7 @@ pub(crate) fn compile_fn(
     }
 
     // Define debuginfo for function
-    let isa = module.isa();
     let debug_context = &mut cx.debug_context;
-    let unwind_context = &mut cx.unwind_context;
     cx.profiler.generic_activity("generate debug info").run(|| {
         if let Some(debug_context) = debug_context {
             codegened_func.func_debug_cx.unwrap().finalize(
@@ -260,7 +258,6 @@ pub(crate) fn compile_fn(
                 context,
             );
         }
-        unwind_context.add_function(codegened_func.func_id, &context, isa);
     });
 }
 
@@ -909,7 +906,7 @@ fn codegen_stmt<'tcx>(
         | StatementKind::PlaceMention(..)
         | StatementKind::AscribeUserType(..) => {}
 
-        StatementKind::Coverage { .. } => fx.tcx.dcx().fatal("-Zcoverage is unimplemented"),
+        StatementKind::Coverage { .. } => unreachable!(),
         StatementKind::Intrinsic(ref intrinsic) => match &**intrinsic {
             // We ignore `assume` intrinsics, they are only useful for optimizations
             NonDivergingIntrinsic::Assume(_) => {}
diff --git a/compiler/rustc_codegen_cranelift/src/common.rs b/compiler/rustc_codegen_cranelift/src/common.rs
index 21d0cd2d30f..09317139936 100644
--- a/compiler/rustc_codegen_cranelift/src/common.rs
+++ b/compiler/rustc_codegen_cranelift/src/common.rs
@@ -247,7 +247,6 @@ pub(crate) fn type_sign(ty: Ty<'_>) -> bool {
 
 pub(crate) fn create_wrapper_function(
     module: &mut dyn Module,
-    unwind_context: &mut UnwindContext,
     sig: Signature,
     wrapper_name: &str,
     callee_name: &str,
@@ -280,7 +279,6 @@ pub(crate) fn create_wrapper_function(
         bcx.finalize();
     }
     module.define_function(wrapper_func_id, &mut ctx).unwrap();
-    unwind_context.add_function(wrapper_func_id, &ctx, module.isa());
 }
 
 pub(crate) struct FunctionCx<'m, 'clif, 'tcx: 'm> {
@@ -395,6 +393,7 @@ impl<'tcx> FunctionCx<'_, '_, 'tcx> {
                 // FIXME Don't force the size to a multiple of <abi_align> bytes once Cranelift gets
                 // a way to specify stack slot alignment.
                 size: (size + abi_align - 1) / abi_align * abi_align,
+                align_shift: 4,
             });
             Pointer::stack_slot(stack_slot)
         } else {
@@ -405,6 +404,7 @@ impl<'tcx> FunctionCx<'_, '_, 'tcx> {
                 // FIXME Don't force the size to a multiple of <abi_align> bytes once Cranelift gets
                 // a way to specify stack slot alignment.
                 size: (size + align) / abi_align * abi_align,
+                align_shift: 4,
             });
             let base_ptr = self.bcx.ins().stack_addr(self.pointer_type, stack_slot, 0);
             let misalign_offset = self.bcx.ins().urem_imm(base_ptr, i64::from(align));
diff --git a/compiler/rustc_codegen_cranelift/src/driver/aot.rs b/compiler/rustc_codegen_cranelift/src/driver/aot.rs
index dcafac21bc7..763d9a48407 100644
--- a/compiler/rustc_codegen_cranelift/src/driver/aot.rs
+++ b/compiler/rustc_codegen_cranelift/src/driver/aot.rs
@@ -26,6 +26,7 @@ use rustc_session::Session;
 use crate::concurrency_limiter::{ConcurrencyLimiter, ConcurrencyLimiterToken};
 use crate::debuginfo::TypeDebugContext;
 use crate::global_asm::GlobalAsmConfig;
+use crate::unwind_module::UnwindModule;
 use crate::{prelude::*, BackendConfig};
 
 struct ModuleCodegenResult {
@@ -318,7 +319,11 @@ fn produce_final_output_artifacts(
     // These are used in linking steps and will be cleaned up afterward.
 }
 
-fn make_module(sess: &Session, backend_config: &BackendConfig, name: String) -> ObjectModule {
+fn make_module(
+    sess: &Session,
+    backend_config: &BackendConfig,
+    name: String,
+) -> UnwindModule<ObjectModule> {
     let isa = crate::build_isa(sess, backend_config);
 
     let mut builder =
@@ -327,16 +332,15 @@ fn make_module(sess: &Session, backend_config: &BackendConfig, name: String) ->
     // is important, while cg_clif cares more about compilation times. Enabling -Zfunction-sections
     // can easily double the amount of time necessary to perform linking.
     builder.per_function_section(sess.opts.unstable_opts.function_sections.unwrap_or(false));
-    ObjectModule::new(builder)
+    UnwindModule::new(ObjectModule::new(builder), true)
 }
 
 fn emit_cgu(
     output_filenames: &OutputFilenames,
     prof: &SelfProfilerRef,
     name: String,
-    module: ObjectModule,
+    module: UnwindModule<ObjectModule>,
     debug: Option<DebugContext>,
-    unwind_context: UnwindContext,
     global_asm_object_file: Option<PathBuf>,
     producer: &str,
 ) -> Result<ModuleCodegenResult, String> {
@@ -346,8 +350,6 @@ fn emit_cgu(
         debug.emit(&mut product);
     }
 
-    unwind_context.emit(&mut product);
-
     let module_regular = emit_module(
         output_filenames,
         prof,
@@ -494,7 +496,6 @@ fn module_codegen(
 
             let mut cx = crate::CodegenCx::new(
                 tcx,
-                backend_config.clone(),
                 module.isa(),
                 tcx.sess.opts.debuginfo != DebugInfo::None,
                 cgu_name,
@@ -531,13 +532,7 @@ fn module_codegen(
                     }
                 }
             }
-            crate::main_shim::maybe_create_entry_wrapper(
-                tcx,
-                &mut module,
-                &mut cx.unwind_context,
-                false,
-                cgu.is_primary(),
-            );
+            crate::main_shim::maybe_create_entry_wrapper(tcx, &mut module, false, cgu.is_primary());
 
             let cgu_name = cgu.name().as_str().to_owned();
 
@@ -571,7 +566,6 @@ fn module_codegen(
                     cgu_name,
                     module,
                     cx.debug_context,
-                    cx.unwind_context,
                     global_asm_object_file,
                     &producer,
                 )
@@ -665,13 +659,10 @@ pub(crate) fn run_aot(
     });
 
     let mut allocator_module = make_module(tcx.sess, &backend_config, "allocator_shim".to_string());
-    let mut allocator_unwind_context = UnwindContext::new(allocator_module.isa(), true);
-    let created_alloc_shim =
-        crate::allocator::codegen(tcx, &mut allocator_module, &mut allocator_unwind_context);
+    let created_alloc_shim = crate::allocator::codegen(tcx, &mut allocator_module);
 
     let allocator_module = if created_alloc_shim {
-        let mut product = allocator_module.finish();
-        allocator_unwind_context.emit(&mut product);
+        let product = allocator_module.finish();
 
         match emit_module(
             tcx.output_filenames(()),
diff --git a/compiler/rustc_codegen_cranelift/src/driver/jit.rs b/compiler/rustc_codegen_cranelift/src/driver/jit.rs
index 4b149131b61..dfee8e714e6 100644
--- a/compiler/rustc_codegen_cranelift/src/driver/jit.rs
+++ b/compiler/rustc_codegen_cranelift/src/driver/jit.rs
@@ -14,12 +14,12 @@ use rustc_session::Session;
 use rustc_span::Symbol;
 
 use crate::debuginfo::TypeDebugContext;
+use crate::unwind_module::UnwindModule;
 use crate::{prelude::*, BackendConfig};
 use crate::{CodegenCx, CodegenMode};
 
 struct JitState {
-    backend_config: BackendConfig,
-    jit_module: JITModule,
+    jit_module: UnwindModule<JITModule>,
 }
 
 thread_local! {
@@ -63,7 +63,7 @@ fn create_jit_module(
     tcx: TyCtxt<'_>,
     backend_config: &BackendConfig,
     hotswap: bool,
-) -> (JITModule, CodegenCx) {
+) -> (UnwindModule<JITModule>, CodegenCx) {
     let crate_info = CrateInfo::new(tcx, "dummy_target_cpu".to_string());
 
     let isa = crate::build_isa(tcx.sess, backend_config);
@@ -72,17 +72,11 @@ fn create_jit_module(
     crate::compiler_builtins::register_functions_for_jit(&mut jit_builder);
     jit_builder.symbol_lookup_fn(dep_symbol_lookup_fn(tcx.sess, crate_info));
     jit_builder.symbol("__clif_jit_fn", clif_jit_fn as *const u8);
-    let mut jit_module = JITModule::new(jit_builder);
+    let mut jit_module = UnwindModule::new(JITModule::new(jit_builder), false);
 
-    let mut cx = crate::CodegenCx::new(
-        tcx,
-        backend_config.clone(),
-        jit_module.isa(),
-        false,
-        Symbol::intern("dummy_cgu_name"),
-    );
+    let cx = crate::CodegenCx::new(tcx, jit_module.isa(), false, Symbol::intern("dummy_cgu_name"));
 
-    crate::allocator::codegen(tcx, &mut jit_module, &mut cx.unwind_context);
+    crate::allocator::codegen(tcx, &mut jit_module);
 
     (jit_module, cx)
 }
@@ -128,7 +122,7 @@ pub(crate) fn run_jit(tcx: TyCtxt<'_>, backend_config: BackendConfig) -> ! {
                         );
                     }
                     CodegenMode::JitLazy => {
-                        codegen_shim(tcx, &mut cx, &mut cached_context, &mut jit_module, inst)
+                        codegen_shim(tcx, &mut cached_context, &mut jit_module, inst)
                     }
                 },
                 MonoItem::Static(def_id) => {
@@ -146,18 +140,11 @@ pub(crate) fn run_jit(tcx: TyCtxt<'_>, backend_config: BackendConfig) -> ! {
         tcx.dcx().fatal("Inline asm is not supported in JIT mode");
     }
 
-    crate::main_shim::maybe_create_entry_wrapper(
-        tcx,
-        &mut jit_module,
-        &mut cx.unwind_context,
-        true,
-        true,
-    );
+    crate::main_shim::maybe_create_entry_wrapper(tcx, &mut jit_module, true, true);
 
     tcx.dcx().abort_if_errors();
 
-    jit_module.finalize_definitions().unwrap();
-    unsafe { cx.unwind_context.register_jit(&jit_module) };
+    jit_module.finalize_definitions();
 
     println!(
         "Rustc codegen cranelift will JIT run the executable, because -Cllvm-args=mode=jit was passed"
@@ -177,12 +164,12 @@ pub(crate) fn run_jit(tcx: TyCtxt<'_>, backend_config: BackendConfig) -> ! {
         call_conv: jit_module.target_config().default_call_conv,
     };
     let start_func_id = jit_module.declare_function("main", Linkage::Import, &start_sig).unwrap();
-    let finalized_start: *const u8 = jit_module.get_finalized_function(start_func_id);
+    let finalized_start: *const u8 = jit_module.module.get_finalized_function(start_func_id);
 
     LAZY_JIT_STATE.with(|lazy_jit_state| {
         let mut lazy_jit_state = lazy_jit_state.borrow_mut();
         assert!(lazy_jit_state.is_none());
-        *lazy_jit_state = Some(JitState { backend_config, jit_module });
+        *lazy_jit_state = Some(JitState { jit_module });
     });
 
     let f: extern "C" fn(c_int, *const *const c_char) -> c_int =
@@ -268,7 +255,6 @@ fn jit_fn(instance_ptr: *const Instance<'static>, trampoline_ptr: *const u8) ->
             let mut lazy_jit_state = lazy_jit_state.borrow_mut();
             let lazy_jit_state = lazy_jit_state.as_mut().unwrap();
             let jit_module = &mut lazy_jit_state.jit_module;
-            let backend_config = lazy_jit_state.backend_config.clone();
 
             let name = tcx.symbol_name(instance).name;
             let sig = crate::abi::get_function_sig(
@@ -278,7 +264,7 @@ fn jit_fn(instance_ptr: *const Instance<'static>, trampoline_ptr: *const u8) ->
             );
             let func_id = jit_module.declare_function(name, Linkage::Export, &sig).unwrap();
 
-            let current_ptr = jit_module.read_got_entry(func_id);
+            let current_ptr = jit_module.module.read_got_entry(func_id);
 
             // If the function's GOT entry has already been updated to point at something other
             // than the shim trampoline, don't re-jit but just return the new pointer instead.
@@ -288,11 +274,10 @@ fn jit_fn(instance_ptr: *const Instance<'static>, trampoline_ptr: *const u8) ->
                 return current_ptr;
             }
 
-            jit_module.prepare_for_function_redefine(func_id).unwrap();
+            jit_module.module.prepare_for_function_redefine(func_id).unwrap();
 
             let mut cx = crate::CodegenCx::new(
                 tcx,
-                backend_config,
                 jit_module.isa(),
                 false,
                 Symbol::intern("dummy_cgu_name"),
@@ -300,9 +285,8 @@ fn jit_fn(instance_ptr: *const Instance<'static>, trampoline_ptr: *const u8) ->
             codegen_and_compile_fn(tcx, &mut cx, &mut Context::new(), jit_module, instance);
 
             assert!(cx.global_asm.is_empty());
-            jit_module.finalize_definitions().unwrap();
-            unsafe { cx.unwind_context.register_jit(&jit_module) };
-            jit_module.get_finalized_function(func_id)
+            jit_module.finalize_definitions();
+            jit_module.module.get_finalized_function(func_id)
         })
     })
 }
@@ -310,7 +294,7 @@ fn jit_fn(instance_ptr: *const Instance<'static>, trampoline_ptr: *const u8) ->
 fn dep_symbol_lookup_fn(
     sess: &Session,
     crate_info: CrateInfo,
-) -> Box<dyn Fn(&str) -> Option<*const u8>> {
+) -> Box<dyn Fn(&str) -> Option<*const u8> + Send> {
     use rustc_middle::middle::dependency_format::Linkage;
 
     let mut dylib_paths = Vec::new();
@@ -362,9 +346,8 @@ fn dep_symbol_lookup_fn(
 
 fn codegen_shim<'tcx>(
     tcx: TyCtxt<'tcx>,
-    cx: &mut CodegenCx,
     cached_context: &mut Context,
-    module: &mut JITModule,
+    module: &mut UnwindModule<JITModule>,
     inst: Instance<'tcx>,
 ) {
     let pointer_type = module.target_config().pointer_type();
@@ -413,5 +396,4 @@ fn codegen_shim<'tcx>(
     trampoline_builder.ins().return_(&ret_vals);
 
     module.define_function(func_id, context).unwrap();
-    cx.unwind_context.add_function(func_id, context, module.isa());
 }
diff --git a/compiler/rustc_codegen_cranelift/src/inline_asm.rs b/compiler/rustc_codegen_cranelift/src/inline_asm.rs
index c6b26dd873b..c88230c9360 100644
--- a/compiler/rustc_codegen_cranelift/src/inline_asm.rs
+++ b/compiler/rustc_codegen_cranelift/src/inline_asm.rs
@@ -113,13 +113,7 @@ pub(crate) fn codegen_inline_asm_terminator<'tcx>(
                     );
                     let sig =
                         get_function_sig(fx.tcx, fx.target_config.default_call_conv, instance);
-                    create_wrapper_function(
-                        fx.module,
-                        &mut fx.cx.unwind_context,
-                        sig,
-                        &wrapper_name,
-                        symbol.name,
-                    );
+                    create_wrapper_function(fx.module, sig, &wrapper_name, symbol.name);
 
                     CInlineAsmOperand::Symbol { symbol: wrapper_name }
                 } else {
@@ -283,13 +277,7 @@ pub(crate) fn codegen_naked_asm<'tcx>(
                     );
                     let sig =
                         get_function_sig(tcx, module.target_config().default_call_conv, instance);
-                    create_wrapper_function(
-                        module,
-                        &mut cx.unwind_context,
-                        sig,
-                        &wrapper_name,
-                        symbol.name,
-                    );
+                    create_wrapper_function(module, sig, &wrapper_name, symbol.name);
 
                     CInlineAsmOperand::Symbol { symbol: wrapper_name }
                 } else {
diff --git a/compiler/rustc_codegen_cranelift/src/intrinsics/llvm_x86.rs b/compiler/rustc_codegen_cranelift/src/intrinsics/llvm_x86.rs
index d454f3c1de7..399518e58d8 100644
--- a/compiler/rustc_codegen_cranelift/src/intrinsics/llvm_x86.rs
+++ b/compiler/rustc_codegen_cranelift/src/intrinsics/llvm_x86.rs
@@ -459,11 +459,20 @@ pub(crate) fn codegen_x86_llvm_intrinsic_call<'tcx>(
             intrinsic_args!(fx, args => (a); intrinsic);
             let a = a.load_scalar(fx);
 
+            let value = fx.bcx.ins().x86_cvtt2dq(types::I32X4, a);
+            let cvalue = CValue::by_val(value, ret.layout());
+            ret.write_cvalue(fx, cvalue);
+        }
+        "llvm.x86.sse2.cvtps2dq" => {
+            // https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_mm_cvtps_epi32
+            intrinsic_args!(fx, args => (a); intrinsic);
+            let a = a.load_scalar(fx);
+
             // Using inline asm instead of fcvt_to_sint_sat as unrepresentable values are turned
             // into 0x80000000 for which Cranelift doesn't have a native instruction.
             codegen_inline_asm_inner(
                 fx,
-                &[InlineAsmTemplatePiece::String(format!("cvttps2dq xmm0, xmm0"))],
+                &[InlineAsmTemplatePiece::String(format!("cvtps2dq xmm0, xmm0"))],
                 &[CInlineAsmOperand::InOut {
                     reg: InlineAsmRegOrRegClass::Reg(InlineAsmReg::X86(X86InlineAsmReg::xmm0)),
                     _late: true,
@@ -1416,6 +1425,36 @@ pub(crate) fn codegen_x86_llvm_intrinsic_call<'tcx>(
             ret.write_cvalue(fx, res);
         }
 
+        "llvm.x86.rdtsc" => {
+            // https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_rdtsc&ig_expand=5273
+
+            let res_place = CPlace::new_stack_slot(
+                fx,
+                fx.layout_of(Ty::new_tup(fx.tcx, &[fx.tcx.types.u32, fx.tcx.types.u32])),
+            );
+            let eax_place = res_place.place_field(fx, FieldIdx::new(0));
+            let edx_place = res_place.place_field(fx, FieldIdx::new(1));
+            codegen_inline_asm_inner(
+                fx,
+                &[InlineAsmTemplatePiece::String("rdtsc".to_string())],
+                &[
+                    CInlineAsmOperand::Out {
+                        reg: InlineAsmRegOrRegClass::Reg(InlineAsmReg::X86(X86InlineAsmReg::ax)),
+                        late: true,
+                        place: Some(eax_place),
+                    },
+                    CInlineAsmOperand::Out {
+                        reg: InlineAsmRegOrRegClass::Reg(InlineAsmReg::X86(X86InlineAsmReg::dx)),
+                        late: true,
+                        place: Some(edx_place),
+                    },
+                ],
+                InlineAsmOptions::NOSTACK | InlineAsmOptions::NOMEM,
+            );
+            let res = res_place.to_cvalue(fx);
+            ret.write_cvalue_transmute(fx, res);
+        }
+
         _ => {
             fx.tcx
                 .dcx()
diff --git a/compiler/rustc_codegen_cranelift/src/lib.rs b/compiler/rustc_codegen_cranelift/src/lib.rs
index 06ca52b3903..192e6c91ea3 100644
--- a/compiler/rustc_codegen_cranelift/src/lib.rs
+++ b/compiler/rustc_codegen_cranelift/src/lib.rs
@@ -79,6 +79,7 @@ mod pretty_clif;
 mod toolchain;
 mod trap;
 mod unsize;
+mod unwind_module;
 mod value_and_place;
 mod vtable;
 
@@ -130,22 +131,13 @@ struct CodegenCx {
     global_asm: String,
     inline_asm_index: Cell<usize>,
     debug_context: Option<DebugContext>,
-    unwind_context: UnwindContext,
     cgu_name: Symbol,
 }
 
 impl CodegenCx {
-    fn new(
-        tcx: TyCtxt<'_>,
-        backend_config: BackendConfig,
-        isa: &dyn TargetIsa,
-        debug_info: bool,
-        cgu_name: Symbol,
-    ) -> Self {
+    fn new(tcx: TyCtxt<'_>, isa: &dyn TargetIsa, debug_info: bool, cgu_name: Symbol) -> Self {
         assert_eq!(pointer_ty(tcx), isa.pointer_type());
 
-        let unwind_context =
-            UnwindContext::new(isa, matches!(backend_config.codegen_mode, CodegenMode::Aot));
         let debug_context = if debug_info && !tcx.sess.target.options.is_like_windows {
             Some(DebugContext::new(tcx, isa, cgu_name.as_str()))
         } else {
@@ -158,7 +150,6 @@ impl CodegenCx {
             global_asm: String::new(),
             inline_asm_index: Cell::new(0),
             debug_context,
-            unwind_context,
             cgu_name,
         }
     }
@@ -175,7 +166,7 @@ impl CodegenBackend for CraneliftCodegenBackend {
     }
 
     fn init(&self, sess: &Session) {
-        use rustc_session::config::Lto;
+        use rustc_session::config::{InstrumentCoverage, Lto};
         match sess.lto() {
             Lto::No | Lto::ThinLocal => {}
             Lto::Thin | Lto::Fat => {
@@ -183,6 +174,11 @@ impl CodegenBackend for CraneliftCodegenBackend {
             }
         }
 
+        if sess.opts.cg.instrument_coverage() != InstrumentCoverage::No {
+            sess.dcx()
+                .fatal("`-Cinstrument-coverage` is LLVM specific and not supported by Cranelift");
+        }
+
         let mut config = self.config.borrow_mut();
         if config.is_none() {
             let new_config = BackendConfig::from_opts(&sess.opts.cg.llvm_args)
diff --git a/compiler/rustc_codegen_cranelift/src/main_shim.rs b/compiler/rustc_codegen_cranelift/src/main_shim.rs
index f9a729618a5..33d3f9b8a90 100644
--- a/compiler/rustc_codegen_cranelift/src/main_shim.rs
+++ b/compiler/rustc_codegen_cranelift/src/main_shim.rs
@@ -11,8 +11,7 @@ use crate::prelude::*;
 /// users main function.
 pub(crate) fn maybe_create_entry_wrapper(
     tcx: TyCtxt<'_>,
-    module: &mut impl Module,
-    unwind_context: &mut UnwindContext,
+    module: &mut dyn Module,
     is_jit: bool,
     is_primary_cgu: bool,
 ) {
@@ -36,12 +35,11 @@ pub(crate) fn maybe_create_entry_wrapper(
         return;
     }
 
-    create_entry_fn(tcx, module, unwind_context, main_def_id, is_jit, is_main_fn, sigpipe);
+    create_entry_fn(tcx, module, main_def_id, is_jit, is_main_fn, sigpipe);
 
     fn create_entry_fn(
         tcx: TyCtxt<'_>,
-        m: &mut impl Module,
-        unwind_context: &mut UnwindContext,
+        m: &mut dyn Module,
         rust_main_def_id: DefId,
         ignore_lang_start_wrapper: bool,
         is_main_fn: bool,
@@ -170,7 +168,5 @@ pub(crate) fn maybe_create_entry_wrapper(
         if let Err(err) = m.define_function(cmain_func_id, &mut ctx) {
             tcx.dcx().fatal(format!("entry symbol `{entry_name}` defined multiple times: {err}"));
         }
-
-        unwind_context.add_function(cmain_func_id, &ctx, m.isa());
     }
 }
diff --git a/compiler/rustc_codegen_cranelift/src/unwind_module.rs b/compiler/rustc_codegen_cranelift/src/unwind_module.rs
new file mode 100644
index 00000000000..b950aaa29ce
--- /dev/null
+++ b/compiler/rustc_codegen_cranelift/src/unwind_module.rs
@@ -0,0 +1,115 @@
+use cranelift_codegen::control::ControlPlane;
+use cranelift_codegen::ir::{Function, Signature};
+use cranelift_codegen::isa::{TargetFrontendConfig, TargetIsa};
+use cranelift_codegen::{Context, FinalizedMachReloc};
+use cranelift_module::{
+    DataDescription, DataId, FuncId, FuncOrDataId, Linkage, Module, ModuleDeclarations,
+    ModuleResult,
+};
+use cranelift_object::{ObjectModule, ObjectProduct};
+
+use crate::UnwindContext;
+
+/// A wrapper around a [Module] which adds any defined function to the [UnwindContext].
+pub(crate) struct UnwindModule<T> {
+    pub(crate) module: T,
+    unwind_context: UnwindContext,
+}
+
+impl<T: Module> UnwindModule<T> {
+    pub(crate) fn new(module: T, pic_eh_frame: bool) -> Self {
+        let unwind_context = UnwindContext::new(module.isa(), pic_eh_frame);
+        UnwindModule { module, unwind_context }
+    }
+}
+
+impl UnwindModule<ObjectModule> {
+    pub(crate) fn finish(self) -> ObjectProduct {
+        let mut product = self.module.finish();
+        self.unwind_context.emit(&mut product);
+        product
+    }
+}
+
+#[cfg(feature = "jit")]
+impl UnwindModule<cranelift_jit::JITModule> {
+    pub(crate) fn finalize_definitions(&mut self) {
+        self.module.finalize_definitions().unwrap();
+        let prev_unwind_context = std::mem::replace(
+            &mut self.unwind_context,
+            UnwindContext::new(self.module.isa(), false),
+        );
+        unsafe { prev_unwind_context.register_jit(&self.module) };
+    }
+}
+
+impl<T: Module> Module for UnwindModule<T> {
+    fn isa(&self) -> &dyn TargetIsa {
+        self.module.isa()
+    }
+
+    fn declarations(&self) -> &ModuleDeclarations {
+        self.module.declarations()
+    }
+
+    fn get_name(&self, name: &str) -> Option<FuncOrDataId> {
+        self.module.get_name(name)
+    }
+
+    fn target_config(&self) -> TargetFrontendConfig {
+        self.module.target_config()
+    }
+
+    fn declare_function(
+        &mut self,
+        name: &str,
+        linkage: Linkage,
+        signature: &Signature,
+    ) -> ModuleResult<FuncId> {
+        self.module.declare_function(name, linkage, signature)
+    }
+
+    fn declare_anonymous_function(&mut self, signature: &Signature) -> ModuleResult<FuncId> {
+        self.module.declare_anonymous_function(signature)
+    }
+
+    fn declare_data(
+        &mut self,
+        name: &str,
+        linkage: Linkage,
+        writable: bool,
+        tls: bool,
+    ) -> ModuleResult<DataId> {
+        self.module.declare_data(name, linkage, writable, tls)
+    }
+
+    fn declare_anonymous_data(&mut self, writable: bool, tls: bool) -> ModuleResult<DataId> {
+        self.module.declare_anonymous_data(writable, tls)
+    }
+
+    fn define_function_with_control_plane(
+        &mut self,
+        func: FuncId,
+        ctx: &mut Context,
+        ctrl_plane: &mut ControlPlane,
+    ) -> ModuleResult<()> {
+        self.module.define_function_with_control_plane(func, ctx, ctrl_plane)?;
+        self.unwind_context.add_function(func, ctx, self.module.isa());
+        Ok(())
+    }
+
+    fn define_function_bytes(
+        &mut self,
+        _func_id: FuncId,
+        _func: &Function,
+        _alignment: u64,
+        _bytes: &[u8],
+        _relocs: &[FinalizedMachReloc],
+    ) -> ModuleResult<()> {
+        unimplemented!()
+    }
+
+    fn define_data(&mut self, data_id: DataId, data: &DataDescription) -> ModuleResult<()> {
+        self.module.define_data(data_id, data)
+    }
+}
diff --git a/compiler/rustc_codegen_gcc/src/common.rs b/compiler/rustc_codegen_gcc/src/common.rs
index 548c23cc794..230fe4f5871 100644
--- a/compiler/rustc_codegen_gcc/src/common.rs
+++ b/compiler/rustc_codegen_gcc/src/common.rs
@@ -28,6 +28,19 @@ impl<'gcc, 'tcx> CodegenCx<'gcc, 'tcx> {
         global
         // TODO(antoyo): set linkage.
     }
+
+    pub fn const_bitcast(&self, value: RValue<'gcc>, typ: Type<'gcc>) -> RValue<'gcc> {
+        if value.get_type() == self.bool_type.make_pointer() {
+            if let Some(pointee) = typ.get_pointee() {
+                if pointee.dyncast_vector().is_some() {
+                    panic!()
+                }
+            }
+        }
+        // NOTE: since bitcast makes a value non-constant, don't bitcast if not necessary as some
+        // SIMD builtins require a constant value.
+        self.bitcast_if_needed(value, typ)
+    }
 }
 
 pub fn bytes_in_context<'gcc, 'tcx>(cx: &CodegenCx<'gcc, 'tcx>, bytes: &[u8]) -> RValue<'gcc> {
@@ -239,19 +252,6 @@ impl<'gcc, 'tcx> ConstMethods<'tcx> for CodegenCx<'gcc, 'tcx> {
         const_alloc_to_gcc(self, alloc)
     }
 
-    fn const_bitcast(&self, value: RValue<'gcc>, typ: Type<'gcc>) -> RValue<'gcc> {
-        if value.get_type() == self.bool_type.make_pointer() {
-            if let Some(pointee) = typ.get_pointee() {
-                if pointee.dyncast_vector().is_some() {
-                    panic!()
-                }
-            }
-        }
-        // NOTE: since bitcast makes a value non-constant, don't bitcast if not necessary as some
-        // SIMD builtins require a constant value.
-        self.bitcast_if_needed(value, typ)
-    }
-
     fn const_ptr_byte_offset(&self, base_addr: Self::Value, offset: abi::Size) -> Self::Value {
         self.context
             .new_array_access(None, base_addr, self.const_usize(offset.bytes()))
diff --git a/compiler/rustc_codegen_gcc/src/context.rs b/compiler/rustc_codegen_gcc/src/context.rs
index 4a1f5188a80..6231b09552c 100644
--- a/compiler/rustc_codegen_gcc/src/context.rs
+++ b/compiler/rustc_codegen_gcc/src/context.rs
@@ -27,7 +27,6 @@ use crate::callee::get_fn;
 use crate::common::SignType;
 
 pub struct CodegenCx<'gcc, 'tcx> {
-    pub check_overflow: bool,
     pub codegen_unit: &'tcx CodegenUnit<'tcx>,
     pub context: &'gcc Context<'gcc>,
 
@@ -134,8 +133,6 @@ impl<'gcc, 'tcx> CodegenCx<'gcc, 'tcx> {
         tcx: TyCtxt<'tcx>,
         supports_128bit_integers: bool,
     ) -> Self {
-        let check_overflow = tcx.sess.overflow_checks();
-
         let create_type = |ctype, rust_type| {
             let layout = tcx.layout_of(ParamEnv::reveal_all().and(rust_type)).unwrap();
             let align = layout.align.abi.bytes();
@@ -271,7 +268,6 @@ impl<'gcc, 'tcx> CodegenCx<'gcc, 'tcx> {
         }
 
         let mut cx = Self {
-            check_overflow,
             codegen_unit,
             context,
             current_func: RefCell::new(None),
@@ -511,10 +507,6 @@ impl<'gcc, 'tcx> MiscMethods<'tcx> for CodegenCx<'gcc, 'tcx> {
         &self.tcx.sess
     }
 
-    fn check_overflow(&self) -> bool {
-        self.check_overflow
-    }
-
     fn codegen_unit(&self) -> &'tcx CodegenUnit<'tcx> {
         self.codegen_unit
     }
diff --git a/compiler/rustc_codegen_gcc/src/type_.rs b/compiler/rustc_codegen_gcc/src/type_.rs
index 68471b028be..4caff2e6310 100644
--- a/compiler/rustc_codegen_gcc/src/type_.rs
+++ b/compiler/rustc_codegen_gcc/src/type_.rs
@@ -89,13 +89,34 @@ impl<'gcc, 'tcx> CodegenCx<'gcc, 'tcx> {
             ty::FloatTy::F128 => self.type_f128(),
         }
     }
-}
 
-impl<'gcc, 'tcx> BaseTypeMethods<'tcx> for CodegenCx<'gcc, 'tcx> {
-    fn type_i1(&self) -> Type<'gcc> {
+    pub fn type_i1(&self) -> Type<'gcc> {
         self.bool_type
     }
 
+    pub fn type_struct(&self, fields: &[Type<'gcc>], packed: bool) -> Type<'gcc> {
+        let types = fields.to_vec();
+        if let Some(typ) = self.struct_types.borrow().get(fields) {
+            return *typ;
+        }
+        let fields: Vec<_> = fields
+            .iter()
+            .enumerate()
+            .map(|(index, field)| {
+                self.context.new_field(None, *field, format!("field{}_TODO", index))
+            })
+            .collect();
+        let typ = self.context.new_struct_type(None, "struct", &fields).as_type();
+        if packed {
+            #[cfg(feature = "master")]
+            typ.set_packed();
+        }
+        self.struct_types.borrow_mut().insert(types, typ);
+        typ
+    }
+}
+
+impl<'gcc, 'tcx> BaseTypeMethods<'tcx> for CodegenCx<'gcc, 'tcx> {
     fn type_i8(&self) -> Type<'gcc> {
         self.i8_type
     }
@@ -131,7 +152,7 @@ impl<'gcc, 'tcx> BaseTypeMethods<'tcx> for CodegenCx<'gcc, 'tcx> {
     fn type_f64(&self) -> Type<'gcc> {
         self.double_type
     }
-    
+
     fn type_f128(&self) -> Type<'gcc> {
         unimplemented!("f16_f128")
     }
@@ -140,27 +161,6 @@ impl<'gcc, 'tcx> BaseTypeMethods<'tcx> for CodegenCx<'gcc, 'tcx> {
         self.context.new_function_pointer_type(None, return_type, params, false)
     }
 
-    fn type_struct(&self, fields: &[Type<'gcc>], packed: bool) -> Type<'gcc> {
-        let types = fields.to_vec();
-        if let Some(typ) = self.struct_types.borrow().get(fields) {
-            return *typ;
-        }
-        let fields: Vec<_> = fields
-            .iter()
-            .enumerate()
-            .map(|(index, field)| {
-                self.context.new_field(None, *field, format!("field{}_TODO", index))
-            })
-            .collect();
-        let typ = self.context.new_struct_type(None, "struct", &fields).as_type();
-        if packed {
-            #[cfg(feature = "master")]
-            typ.set_packed();
-        }
-        self.struct_types.borrow_mut().insert(types, typ);
-        typ
-    }
-
     fn type_kind(&self, typ: Type<'gcc>) -> TypeKind {
         if self.is_int_type_or_bool(typ) {
             TypeKind::Integer
diff --git a/compiler/rustc_codegen_llvm/src/common.rs b/compiler/rustc_codegen_llvm/src/common.rs
index 4ffc92eb633..d42c6ed827a 100644
--- a/compiler/rustc_codegen_llvm/src/common.rs
+++ b/compiler/rustc_codegen_llvm/src/common.rs
@@ -329,10 +329,6 @@ impl<'ll, 'tcx> ConstMethods<'tcx> for CodegenCx<'ll, 'tcx> {
         const_alloc_to_llvm(self, alloc, /*static*/ false)
     }
 
-    fn const_bitcast(&self, val: &'ll Value, ty: &'ll Type) -> &'ll Value {
-        self.const_bitcast(val, ty)
-    }
-
     fn const_ptr_byte_offset(&self, base_addr: Self::Value, offset: abi::Size) -> Self::Value {
         unsafe {
             llvm::LLVMConstInBoundsGEP2(
diff --git a/compiler/rustc_codegen_llvm/src/context.rs b/compiler/rustc_codegen_llvm/src/context.rs
index 7d92888feee..1a8e8efdae5 100644
--- a/compiler/rustc_codegen_llvm/src/context.rs
+++ b/compiler/rustc_codegen_llvm/src/context.rs
@@ -3,6 +3,7 @@ use crate::back::write::to_llvm_code_model;
 use crate::callee::get_fn;
 use crate::coverageinfo;
 use crate::debuginfo;
+use crate::debuginfo::metadata::apply_vcall_visibility_metadata;
 use crate::llvm;
 use crate::llvm_util;
 use crate::type_::Type;
@@ -43,7 +44,6 @@ use std::str;
 /// All other LLVM data structures in the `CodegenCx` are tied to that `llvm::Context`.
 pub struct CodegenCx<'ll, 'tcx> {
     pub tcx: TyCtxt<'tcx>,
-    pub check_overflow: bool,
     pub use_dll_storage_attrs: bool,
     pub tls_model: llvm::ThreadLocalMode,
 
@@ -441,8 +441,6 @@ impl<'ll, 'tcx> CodegenCx<'ll, 'tcx> {
         // start) and then strongly recommending static linkage on Windows!
         let use_dll_storage_attrs = tcx.sess.target.is_like_windows;
 
-        let check_overflow = tcx.sess.overflow_checks();
-
         let tls_model = to_llvm_tls_model(tcx.sess.tls_model());
 
         let (llcx, llmod) = (&*llvm_module.llcx, llvm_module.llmod());
@@ -466,7 +464,6 @@ impl<'ll, 'tcx> CodegenCx<'ll, 'tcx> {
 
         CodegenCx {
             tcx,
-            check_overflow,
             use_dll_storage_attrs,
             tls_model,
             llmod,
@@ -522,6 +519,15 @@ impl<'ll, 'tcx> MiscMethods<'tcx> for CodegenCx<'ll, 'tcx> {
         &self.vtables
     }
 
+    fn apply_vcall_visibility_metadata(
+        &self,
+        ty: Ty<'tcx>,
+        poly_trait_ref: Option<ty::PolyExistentialTraitRef<'tcx>>,
+        vtable: &'ll Value,
+    ) {
+        apply_vcall_visibility_metadata(self, ty, poly_trait_ref, vtable);
+    }
+
     fn get_fn(&self, instance: Instance<'tcx>) -> &'ll Value {
         get_fn(self, instance)
     }
@@ -596,10 +602,6 @@ impl<'ll, 'tcx> MiscMethods<'tcx> for CodegenCx<'ll, 'tcx> {
         self.tcx.sess
     }
 
-    fn check_overflow(&self) -> bool {
-        self.check_overflow
-    }
-
     fn codegen_unit(&self) -> &'tcx CodegenUnit<'tcx> {
         self.codegen_unit
     }
diff --git a/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs b/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs
index 8de4e0effad..742bfd76590 100644
--- a/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs
+++ b/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs
@@ -1449,12 +1449,18 @@ fn build_vtable_type_di_node<'ll, 'tcx>(
     .di_node
 }
 
-fn vcall_visibility_metadata<'ll, 'tcx>(
+pub(crate) fn apply_vcall_visibility_metadata<'ll, 'tcx>(
     cx: &CodegenCx<'ll, 'tcx>,
     ty: Ty<'tcx>,
     trait_ref: Option<PolyExistentialTraitRef<'tcx>>,
     vtable: &'ll Value,
 ) {
+    // FIXME(flip1995): The virtual function elimination optimization only works with full LTO in
+    // LLVM at the moment.
+    if !cx.sess().opts.unstable_opts.virtual_function_elimination || cx.sess().lto() != Lto::Fat {
+        return;
+    }
+
     enum VCallVisibility {
         Public = 0,
         LinkageUnit = 1,
@@ -1531,12 +1537,6 @@ pub fn create_vtable_di_node<'ll, 'tcx>(
     poly_trait_ref: Option<ty::PolyExistentialTraitRef<'tcx>>,
     vtable: &'ll Value,
 ) {
-    // FIXME(flip1995): The virtual function elimination optimization only works with full LTO in
-    // LLVM at the moment.
-    if cx.sess().opts.unstable_opts.virtual_function_elimination && cx.sess().lto() == Lto::Fat {
-        vcall_visibility_metadata(cx, ty, poly_trait_ref, vtable);
-    }
-
     if cx.dbg_cx.is_none() {
         return;
     }
diff --git a/compiler/rustc_codegen_llvm/src/lib.rs b/compiler/rustc_codegen_llvm/src/lib.rs
index 4b7a2643007..ed0989a0ba4 100644
--- a/compiler/rustc_codegen_llvm/src/lib.rs
+++ b/compiler/rustc_codegen_llvm/src/lib.rs
@@ -274,10 +274,11 @@ impl CodegenBackend for LlvmCodegenBackend {
             |tcx, ()| llvm_util::global_llvm_features(tcx.sess, true)
     }
 
-    fn print(&self, req: &PrintRequest, out: &mut dyn PrintBackendInfo, sess: &Session) {
+    fn print(&self, req: &PrintRequest, out: &mut String, sess: &Session) {
+        use std::fmt::Write;
         match req.kind {
             PrintKind::RelocationModels => {
-                writeln!(out, "Available relocation models:");
+                writeln!(out, "Available relocation models:").unwrap();
                 for name in &[
                     "static",
                     "pic",
@@ -288,25 +289,25 @@ impl CodegenBackend for LlvmCodegenBackend {
                     "ropi-rwpi",
                     "default",
                 ] {
-                    writeln!(out, "    {name}");
+                    writeln!(out, "    {name}").unwrap();
                 }
-                writeln!(out);
+                writeln!(out).unwrap();
             }
             PrintKind::CodeModels => {
-                writeln!(out, "Available code models:");
+                writeln!(out, "Available code models:").unwrap();
                 for name in &["tiny", "small", "kernel", "medium", "large"] {
-                    writeln!(out, "    {name}");
+                    writeln!(out, "    {name}").unwrap();
                 }
-                writeln!(out);
+                writeln!(out).unwrap();
             }
             PrintKind::TlsModels => {
-                writeln!(out, "Available TLS models:");
+                writeln!(out, "Available TLS models:").unwrap();
                 for name in
                     &["global-dynamic", "local-dynamic", "initial-exec", "local-exec", "emulated"]
                 {
-                    writeln!(out, "    {name}");
+                    writeln!(out, "    {name}").unwrap();
                 }
-                writeln!(out);
+                writeln!(out).unwrap();
             }
             PrintKind::StackProtectorStrategies => {
                 writeln!(
@@ -332,7 +333,8 @@ impl CodegenBackend for LlvmCodegenBackend {
     none
         Do not generate stack canaries.
 "#
-                );
+                )
+                .unwrap();
             }
             _other => llvm_util::print(req, out, sess),
         }
diff --git a/compiler/rustc_codegen_llvm/src/llvm_util.rs b/compiler/rustc_codegen_llvm/src/llvm_util.rs
index 7e0f264a4ae..0e89e66be49 100644
--- a/compiler/rustc_codegen_llvm/src/llvm_util.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm_util.rs
@@ -6,7 +6,6 @@ use crate::errors::{
 use crate::llvm;
 use libc::c_int;
 use rustc_codegen_ssa::base::wants_wasm_eh;
-use rustc_codegen_ssa::traits::PrintBackendInfo;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::small_c_str::SmallCStr;
 use rustc_fs_util::path_to_c_string;
@@ -18,6 +17,7 @@ use rustc_target::spec::{MergeFunctions, PanicStrategy};
 use rustc_target::target_features::RUSTC_SPECIFIC_FEATURES;
 
 use std::ffi::{c_char, c_void, CStr, CString};
+use std::fmt::Write;
 use std::path::Path;
 use std::ptr;
 use std::slice;
@@ -372,7 +372,7 @@ fn llvm_target_features(tm: &llvm::TargetMachine) -> Vec<(&str, &str)> {
     ret
 }
 
-fn print_target_features(out: &mut dyn PrintBackendInfo, sess: &Session, tm: &llvm::TargetMachine) {
+fn print_target_features(out: &mut String, sess: &Session, tm: &llvm::TargetMachine) {
     let mut llvm_target_features = llvm_target_features(tm);
     let mut known_llvm_target_features = FxHashSet::<&'static str>::default();
     let mut rustc_target_features = sess
@@ -412,24 +412,26 @@ fn print_target_features(out: &mut dyn PrintBackendInfo, sess: &Session, tm: &ll
         .max()
         .unwrap_or(0);
 
-    writeln!(out, "Features supported by rustc for this target:");
+    writeln!(out, "Features supported by rustc for this target:").unwrap();
     for (feature, desc) in &rustc_target_features {
-        writeln!(out, "    {feature:max_feature_len$} - {desc}.");
+        writeln!(out, "    {feature:max_feature_len$} - {desc}.").unwrap();
     }
-    writeln!(out, "\nCode-generation features supported by LLVM for this target:");
+    writeln!(out, "\nCode-generation features supported by LLVM for this target:").unwrap();
     for (feature, desc) in &llvm_target_features {
-        writeln!(out, "    {feature:max_feature_len$} - {desc}.");
+        writeln!(out, "    {feature:max_feature_len$} - {desc}.").unwrap();
     }
     if llvm_target_features.is_empty() {
-        writeln!(out, "    Target features listing is not supported by this LLVM version.");
+        writeln!(out, "    Target features listing is not supported by this LLVM version.")
+            .unwrap();
     }
-    writeln!(out, "\nUse +feature to enable a feature, or -feature to disable it.");
-    writeln!(out, "For example, rustc -C target-cpu=mycpu -C target-feature=+feature1,-feature2\n");
-    writeln!(out, "Code-generation features cannot be used in cfg or #[target_feature],");
-    writeln!(out, "and may be renamed or removed in a future version of LLVM or rustc.\n");
+    writeln!(out, "\nUse +feature to enable a feature, or -feature to disable it.").unwrap();
+    writeln!(out, "For example, rustc -C target-cpu=mycpu -C target-feature=+feature1,-feature2\n")
+        .unwrap();
+    writeln!(out, "Code-generation features cannot be used in cfg or #[target_feature],").unwrap();
+    writeln!(out, "and may be renamed or removed in a future version of LLVM or rustc.\n").unwrap();
 }
 
-pub(crate) fn print(req: &PrintRequest, mut out: &mut dyn PrintBackendInfo, sess: &Session) {
+pub(crate) fn print(req: &PrintRequest, mut out: &mut String, sess: &Session) {
     require_inited();
     let tm = create_informational_target_machine(sess);
     match req.kind {
@@ -440,9 +442,9 @@ pub(crate) fn print(req: &PrintRequest, mut out: &mut dyn PrintBackendInfo, sess
             let cpu_cstring = CString::new(handle_native(sess.target.cpu.as_ref()))
                 .unwrap_or_else(|e| bug!("failed to convert to cstring: {}", e));
             unsafe extern "C" fn callback(out: *mut c_void, string: *const c_char, len: usize) {
-                let out = &mut *(out as *mut &mut dyn PrintBackendInfo);
+                let out = &mut *(out as *mut &mut String);
                 let bytes = slice::from_raw_parts(string as *const u8, len);
-                write!(out, "{}", String::from_utf8_lossy(bytes));
+                write!(out, "{}", String::from_utf8_lossy(bytes)).unwrap();
             }
             unsafe {
                 llvm::LLVMRustPrintTargetCPUs(
diff --git a/compiler/rustc_codegen_llvm/src/type_.rs b/compiler/rustc_codegen_llvm/src/type_.rs
index a00f09dc40d..f1141c57ced 100644
--- a/compiler/rustc_codegen_llvm/src/type_.rs
+++ b/compiler/rustc_codegen_llvm/src/type_.rs
@@ -127,13 +127,24 @@ impl<'ll> CodegenCx<'ll, '_> {
     pub(crate) fn type_variadic_func(&self, args: &[&'ll Type], ret: &'ll Type) -> &'ll Type {
         unsafe { llvm::LLVMFunctionType(ret, args.as_ptr(), args.len() as c_uint, True) }
     }
-}
 
-impl<'ll, 'tcx> BaseTypeMethods<'tcx> for CodegenCx<'ll, 'tcx> {
-    fn type_i1(&self) -> &'ll Type {
+    pub(crate) fn type_i1(&self) -> &'ll Type {
         unsafe { llvm::LLVMInt1TypeInContext(self.llcx) }
     }
 
+    pub(crate) fn type_struct(&self, els: &[&'ll Type], packed: bool) -> &'ll Type {
+        unsafe {
+            llvm::LLVMStructTypeInContext(
+                self.llcx,
+                els.as_ptr(),
+                els.len() as c_uint,
+                packed as Bool,
+            )
+        }
+    }
+}
+
+impl<'ll, 'tcx> BaseTypeMethods<'tcx> for CodegenCx<'ll, 'tcx> {
     fn type_i8(&self) -> &'ll Type {
         unsafe { llvm::LLVMInt8TypeInContext(self.llcx) }
     }
@@ -178,17 +189,6 @@ impl<'ll, 'tcx> BaseTypeMethods<'tcx> for CodegenCx<'ll, 'tcx> {
         unsafe { llvm::LLVMFunctionType(ret, args.as_ptr(), args.len() as c_uint, False) }
     }
 
-    fn type_struct(&self, els: &[&'ll Type], packed: bool) -> &'ll Type {
-        unsafe {
-            llvm::LLVMStructTypeInContext(
-                self.llcx,
-                els.as_ptr(),
-                els.len() as c_uint,
-                packed as Bool,
-            )
-        }
-    }
-
     fn type_kind(&self, ty: &'ll Type) -> TypeKind {
         unsafe { llvm::LLVMRustGetTypeKind(ty).to_generic() }
     }
diff --git a/compiler/rustc_codegen_ssa/src/back/link.rs b/compiler/rustc_codegen_ssa/src/back/link.rs
index d509e4ce56d..da4fa41e2aa 100644
--- a/compiler/rustc_codegen_ssa/src/back/link.rs
+++ b/compiler/rustc_codegen_ssa/src/back/link.rs
@@ -45,7 +45,7 @@ use tempfile::Builder as TempFileBuilder;
 
 use itertools::Itertools;
 use std::collections::BTreeSet;
-use std::ffi::{OsStr, OsString};
+use std::ffi::OsString;
 use std::fs::{read, File, OpenOptions};
 use std::io::{BufWriter, Write};
 use std::ops::Deref;
@@ -1306,12 +1306,12 @@ fn link_sanitizer_runtime(
         let filename = format!("rustc{channel}_rt.{name}");
         let path = find_sanitizer_runtime(sess, &filename);
         let rpath = path.to_str().expect("non-utf8 component in path");
-        linker.args(&["-Wl,-rpath", "-Xlinker", rpath]);
+        linker.cc_args(&["-Wl,-rpath", "-Xlinker", rpath]);
         linker.link_dylib_by_name(&filename, false, true);
     } else if sess.target.is_like_msvc && flavor == LinkerFlavor::Msvc(Lld::No) && name == "asan" {
         // MSVC provides the `/INFERASANLIBS` argument to automatically find the
         // compatible ASAN library.
-        linker.arg("/INFERASANLIBS");
+        linker.link_arg("/INFERASANLIBS");
     } else {
         let filename = format!("librustc{channel}_rt.{name}.a");
         let path = find_sanitizer_runtime(sess, &filename).join(&filename);
@@ -1888,9 +1888,9 @@ fn add_post_link_objects(
 /// FIXME: Determine where exactly these args need to be inserted.
 fn add_pre_link_args(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) {
     if let Some(args) = sess.target.pre_link_args.get(&flavor) {
-        cmd.args(args.iter().map(Deref::deref));
+        cmd.verbatim_args(args.iter().map(Deref::deref));
     }
-    cmd.args(&sess.opts.unstable_opts.pre_link_args);
+    cmd.verbatim_args(&sess.opts.unstable_opts.pre_link_args);
 }
 
 /// Add a link script embedded in the target, if applicable.
@@ -1908,8 +1908,7 @@ fn add_link_script(cmd: &mut dyn Linker, sess: &Session, tmpdir: &Path, crate_ty
                 sess.dcx().emit_fatal(errors::LinkScriptWriteFailure { path, error });
             }
 
-            cmd.arg("--script");
-            cmd.arg(path);
+            cmd.link_arg("--script").link_arg(path);
         }
         _ => {}
     }
@@ -1918,7 +1917,7 @@ fn add_link_script(cmd: &mut dyn Linker, sess: &Session, tmpdir: &Path, crate_ty
 /// Add arbitrary "user defined" args defined from command line.
 /// FIXME: Determine where exactly these args need to be inserted.
 fn add_user_defined_link_args(cmd: &mut dyn Linker, sess: &Session) {
-    cmd.args(&sess.opts.cg.link_args);
+    cmd.verbatim_args(&sess.opts.cg.link_args);
 }
 
 /// Add arbitrary "late link" args defined by the target spec.
@@ -1936,15 +1935,15 @@ fn add_late_link_args(
         });
     if any_dynamic_crate {
         if let Some(args) = sess.target.late_link_args_dynamic.get(&flavor) {
-            cmd.args(args.iter().map(Deref::deref));
+            cmd.verbatim_args(args.iter().map(Deref::deref));
         }
     } else {
         if let Some(args) = sess.target.late_link_args_static.get(&flavor) {
-            cmd.args(args.iter().map(Deref::deref));
+            cmd.verbatim_args(args.iter().map(Deref::deref));
         }
     }
     if let Some(args) = sess.target.late_link_args.get(&flavor) {
-        cmd.args(args.iter().map(Deref::deref));
+        cmd.verbatim_args(args.iter().map(Deref::deref));
     }
 }
 
@@ -1952,7 +1951,7 @@ fn add_late_link_args(
 /// FIXME: Determine where exactly these args need to be inserted.
 fn add_post_link_args(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) {
     if let Some(args) = sess.target.post_link_args.get(&flavor) {
-        cmd.args(args.iter().map(Deref::deref));
+        cmd.verbatim_args(args.iter().map(Deref::deref));
     }
 }
 
@@ -2097,6 +2096,10 @@ fn add_rpath_args(
     codegen_results: &CodegenResults,
     out_filename: &Path,
 ) {
+    if !sess.target.has_rpath {
+        return;
+    }
+
     // FIXME (#2397): At some point we want to rpath our guesses as to
     // where extern libraries might live, based on the
     // add_lib_search_paths
@@ -2115,11 +2118,10 @@ fn add_rpath_args(
         let rpath_config = RPathConfig {
             libs: &*libs,
             out_filename: out_filename.to_path_buf(),
-            has_rpath: sess.target.has_rpath,
             is_like_osx: sess.target.is_like_osx,
             linker_is_gnu: sess.target.linker_flavor.is_gnu(),
         };
-        cmd.args(&rpath::get_rpath_flags(&rpath_config));
+        cmd.cc_args(&rpath::get_rpath_flags(&rpath_config));
     }
 }
 
@@ -2378,7 +2380,7 @@ fn add_order_independent_options(
         } else {
             ""
         };
-        cmd.arg(format!("--dynamic-linker={prefix}ld.so.1"));
+        cmd.link_arg(format!("--dynamic-linker={prefix}ld.so.1"));
     }
 
     if sess.target.eh_frame_header {
@@ -2393,8 +2395,7 @@ fn add_order_independent_options(
     }
 
     if sess.target.os == "emscripten" {
-        cmd.arg("-s");
-        cmd.arg(if sess.panic_strategy() == PanicStrategy::Abort {
+        cmd.cc_arg("-s").cc_arg(if sess.panic_strategy() == PanicStrategy::Abort {
             "DISABLE_EXCEPTION_CATCHING=1"
         } else {
             "DISABLE_EXCEPTION_CATCHING=0"
@@ -2402,22 +2403,21 @@ fn add_order_independent_options(
     }
 
     if flavor == LinkerFlavor::Llbc {
-        cmd.arg("--target");
-        cmd.arg(sess.target.llvm_target.as_ref());
-        cmd.arg("--target-cpu");
-        cmd.arg(&codegen_results.crate_info.target_cpu);
+        cmd.link_args(&[
+            "--target",
+            sess.target.llvm_target.as_ref(),
+            "--target-cpu",
+            &codegen_results.crate_info.target_cpu,
+        ]);
     } else if flavor == LinkerFlavor::Ptx {
-        cmd.arg("--fallback-arch");
-        cmd.arg(&codegen_results.crate_info.target_cpu);
+        cmd.link_args(&["--fallback-arch", &codegen_results.crate_info.target_cpu]);
     } else if flavor == LinkerFlavor::Bpf {
-        cmd.arg("--cpu");
-        cmd.arg(&codegen_results.crate_info.target_cpu);
+        cmd.link_args(&["--cpu", &codegen_results.crate_info.target_cpu]);
         if let Some(feat) = [sess.opts.cg.target_feature.as_str(), &sess.target.options.features]
             .into_iter()
             .find(|feat| !feat.is_empty())
         {
-            cmd.arg("--cpu-features");
-            cmd.arg(feat);
+            cmd.link_args(&["--cpu-features", feat]);
         }
     }
 
@@ -2618,7 +2618,11 @@ fn add_native_libs_from_crate(
             NativeLibKind::WasmImportModule => {}
             NativeLibKind::LinkArg => {
                 if link_static {
-                    cmd.linker_arg(OsStr::new(name), verbatim);
+                    if verbatim {
+                        cmd.verbatim_arg(name);
+                    } else {
+                        cmd.link_arg(name);
+                    }
                 }
             }
         }
@@ -3012,10 +3016,10 @@ fn add_apple_sdk(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) {
             // This is admittedly a bit strange, as on most targets
             // `-isysroot` only applies to include header files, but on Apple
             // targets this also applies to libraries and frameworks.
-            cmd.args(&["-isysroot", &sdk_root]);
+            cmd.cc_args(&["-isysroot", &sdk_root]);
         }
         LinkerFlavor::Darwin(Cc::No, _) => {
-            cmd.args(&["-syslibroot", &sdk_root]);
+            cmd.link_args(&["-syslibroot", &sdk_root]);
         }
         _ => unreachable!(),
     }
@@ -3026,8 +3030,9 @@ fn add_apple_sdk(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) {
         // search path.
 
         // The flags are called `-L` and `-F` both in Clang, ld64 and ldd.
-        cmd.arg(format!("-L{sdk_root}/System/iOSSupport/usr/lib"));
-        cmd.arg(format!("-F{sdk_root}/System/iOSSupport/System/Library/Frameworks"));
+        let sdk_root = Path::new(&sdk_root);
+        cmd.include_path(&sdk_root.join("System/iOSSupport/usr/lib"));
+        cmd.framework_path(&sdk_root.join("System/iOSSupport/System/Library/Frameworks"));
     }
 }
 
@@ -3142,7 +3147,7 @@ fn add_lld_args(
         for path in sess.get_tools_search_paths(false) {
             let linker_path = path.join("gcc-ld");
             linker_path_exists |= linker_path.exists();
-            cmd.arg({
+            cmd.cc_arg({
                 let mut arg = OsString::from("-B");
                 arg.push(linker_path);
                 arg
@@ -3162,7 +3167,7 @@ fn add_lld_args(
     // is to use LLD but the `wasm32-wasip2` target relies on a wrapper around
     // this, `wasm-component-ld`, which is overridden if this option is passed.
     if !sess.target.is_like_wasm {
-        cmd.arg("-fuse-ld=lld");
+        cmd.cc_arg("-fuse-ld=lld");
     }
 
     if !flavor.is_gnu() {
@@ -3186,7 +3191,7 @@ fn add_lld_args(
         // targeting a different linker flavor on macOS, and that's also always
         // the case when targeting WASM.
         if sess.target.linker_flavor != sess.host.linker_flavor {
-            cmd.arg(format!("--target={}", sess.target.llvm_target));
+            cmd.cc_arg(format!("--target={}", sess.target.llvm_target));
         }
     }
 }
diff --git a/compiler/rustc_codegen_ssa/src/back/linker.rs b/compiler/rustc_codegen_ssa/src/back/linker.rs
index a82478900b1..0f75ece9729 100644
--- a/compiler/rustc_codegen_ssa/src/back/linker.rs
+++ b/compiler/rustc_codegen_ssa/src/back/linker.rs
@@ -8,7 +8,7 @@ use std::fs::{self, File};
 use std::io::prelude::*;
 use std::io::{self, BufWriter};
 use std::path::{Path, PathBuf};
-use std::{env, mem, str};
+use std::{env, iter, mem, str};
 
 use rustc_hir::def_id::{CrateNum, LOCAL_CRATE};
 use rustc_metadata::find_native_static_library;
@@ -159,6 +159,102 @@ pub fn get_linker<'a>(
     }
 }
 
+// Note: Ideally neither these helper function, nor the macro-generated inherent methods below
+// would exist, and these functions would live in `trait Linker`.
+// Unfortunately, adding these functions to `trait Linker` make it `dyn`-incompatible.
+// If the methods are added to the trait with `where Self: Sized` bounds, then even a separate
+// implementation of them for `dyn Linker {}` wouldn't work due to a conflict with those
+// uncallable methods in the trait.
+
+/// Just pass the arguments to the linker as is.
+/// It is assumed that they are correctly prepared in advance.
+fn verbatim_args<L: Linker + ?Sized>(
+    l: &mut L,
+    args: impl IntoIterator<Item: AsRef<OsStr>>,
+) -> &mut L {
+    for arg in args {
+        l.cmd().arg(arg);
+    }
+    l
+}
+/// Arguments for the underlying linker.
+/// Add options to pass them through cc wrapper if `Linker` is a cc wrapper.
+fn link_args<L: Linker + ?Sized>(
+    l: &mut L,
+    args: impl IntoIterator<Item: AsRef<OsStr>, IntoIter: ExactSizeIterator>,
+) -> &mut L {
+    let args = args.into_iter();
+    if !l.is_cc() {
+        verbatim_args(l, args);
+    } else if args.len() != 0 {
+        // FIXME: Support arguments with commas, see `rpaths_to_flags` for the example.
+        let mut combined_arg = OsString::from("-Wl");
+        for arg in args {
+            combined_arg.push(",");
+            combined_arg.push(arg);
+        }
+        l.cmd().arg(combined_arg);
+    }
+    l
+}
+/// Arguments for the cc wrapper specifically.
+/// Check that it's indeed a cc wrapper and pass verbatim.
+fn cc_args<L: Linker + ?Sized>(l: &mut L, args: impl IntoIterator<Item: AsRef<OsStr>>) -> &mut L {
+    assert!(l.is_cc());
+    verbatim_args(l, args)
+}
+/// Arguments supported by both underlying linker and cc wrapper, pass verbatim.
+fn link_or_cc_args<L: Linker + ?Sized>(
+    l: &mut L,
+    args: impl IntoIterator<Item: AsRef<OsStr>>,
+) -> &mut L {
+    verbatim_args(l, args)
+}
+
+macro_rules! generate_arg_methods {
+    ($($ty:ty)*) => { $(
+        impl $ty {
+            pub fn verbatim_args(&mut self, args: impl IntoIterator<Item: AsRef<OsStr>>) -> &mut Self {
+                verbatim_args(self, args)
+            }
+            pub fn verbatim_arg(&mut self, arg: impl AsRef<OsStr>) -> &mut Self {
+                verbatim_args(self, iter::once(arg))
+            }
+            pub fn link_args(&mut self, args: impl IntoIterator<Item: AsRef<OsStr>, IntoIter: ExactSizeIterator>) -> &mut Self {
+                link_args(self, args)
+            }
+            pub fn link_arg(&mut self, arg: impl AsRef<OsStr>) -> &mut Self {
+                link_args(self, iter::once(arg))
+            }
+            pub fn cc_args(&mut self, args: impl IntoIterator<Item: AsRef<OsStr>>) -> &mut Self {
+                cc_args(self, args)
+            }
+            pub fn cc_arg(&mut self, arg: impl AsRef<OsStr>) -> &mut Self {
+                cc_args(self, iter::once(arg))
+            }
+            pub fn link_or_cc_args(&mut self, args: impl IntoIterator<Item: AsRef<OsStr>>) -> &mut Self {
+                link_or_cc_args(self, args)
+            }
+            pub fn link_or_cc_arg(&mut self, arg: impl AsRef<OsStr>) -> &mut Self {
+                link_or_cc_args(self, iter::once(arg))
+            }
+        }
+    )* }
+}
+
+generate_arg_methods! {
+    GccLinker<'_>
+    MsvcLinker<'_>
+    EmLinker<'_>
+    WasmLd<'_>
+    L4Bender<'_>
+    AixLinker<'_>
+    LlbcLinker<'_>
+    PtxLinker<'_>
+    BpfLinker<'_>
+    dyn Linker + '_
+}
+
 /// Linker abstraction used by `back::link` to build up the command to invoke a
 /// linker.
 ///
@@ -168,6 +264,9 @@ pub fn get_linker<'a>(
 /// MSVC linker (e.g., `link.exe`) is being used.
 pub trait Linker {
     fn cmd(&mut self) -> &mut Command;
+    fn is_cc(&self) -> bool {
+        false
+    }
     fn set_output_kind(&mut self, output_kind: LinkOutputKind, out_filename: &Path);
     fn link_dylib_by_name(&mut self, name: &str, verbatim: bool, as_needed: bool);
     fn link_framework_by_name(&mut self, _name: &str, _verbatim: bool, _as_needed: bool) {
@@ -175,10 +274,18 @@ pub trait Linker {
     }
     fn link_staticlib_by_name(&mut self, name: &str, verbatim: bool, whole_archive: bool);
     fn link_staticlib_by_path(&mut self, path: &Path, whole_archive: bool);
-    fn include_path(&mut self, path: &Path);
-    fn framework_path(&mut self, path: &Path);
-    fn output_filename(&mut self, path: &Path);
-    fn add_object(&mut self, path: &Path);
+    fn include_path(&mut self, path: &Path) {
+        link_or_cc_args(link_or_cc_args(self, &["-L"]), &[path]);
+    }
+    fn framework_path(&mut self, _path: &Path) {
+        bug!("framework path set with unsupported linker")
+    }
+    fn output_filename(&mut self, path: &Path) {
+        link_or_cc_args(link_or_cc_args(self, &["-o"]), &[path]);
+    }
+    fn add_object(&mut self, path: &Path) {
+        link_or_cc_args(self, &[path]);
+    }
     fn gc_sections(&mut self, keep_metadata: bool);
     fn no_gc_sections(&mut self);
     fn full_relro(&mut self);
@@ -198,25 +305,9 @@ pub trait Linker {
     fn add_no_exec(&mut self) {}
     fn add_as_needed(&mut self) {}
     fn reset_per_library_state(&mut self) {}
-    fn linker_arg(&mut self, arg: &OsStr, verbatim: bool) {
-        self.linker_args(&[arg], verbatim);
-    }
-    fn linker_args(&mut self, args: &[&OsStr], _verbatim: bool) {
-        args.into_iter().for_each(|a| {
-            self.cmd().arg(a);
-        });
-    }
 }
 
 impl dyn Linker + '_ {
-    pub fn arg(&mut self, arg: impl AsRef<OsStr>) {
-        self.cmd().arg(arg);
-    }
-
-    pub fn args(&mut self, args: impl IntoIterator<Item: AsRef<OsStr>>) {
-        self.cmd().args(args);
-    }
-
     pub fn take_cmd(&mut self) -> Command {
         mem::replace(self.cmd(), Command::new(""))
     }
@@ -233,14 +324,6 @@ pub struct GccLinker<'a> {
 }
 
 impl<'a> GccLinker<'a> {
-    fn linker_arg(&mut self, arg: impl AsRef<OsStr>) {
-        Linker::linker_arg(self, arg.as_ref(), false);
-    }
-    fn linker_args(&mut self, args: &[impl AsRef<OsStr>]) {
-        let args_vec: Vec<&OsStr> = args.iter().map(|x| x.as_ref()).collect();
-        Linker::linker_args(self, &args_vec, false);
-    }
-
     fn takes_hints(&self) -> bool {
         // Really this function only returns true if the underlying linker
         // configured for a compiler is binutils `ld.bfd` and `ld.gold`. We
@@ -262,7 +345,7 @@ impl<'a> GccLinker<'a> {
             return;
         }
         if self.hinted_static != Some(true) {
-            self.linker_arg("-Bstatic");
+            self.link_arg("-Bstatic");
             self.hinted_static = Some(true);
         }
     }
@@ -272,7 +355,7 @@ impl<'a> GccLinker<'a> {
             return;
         }
         if self.hinted_static != Some(false) {
-            self.linker_arg("-Bdynamic");
+            self.link_arg("-Bdynamic");
             self.hinted_static = Some(false);
         }
     }
@@ -281,7 +364,7 @@ impl<'a> GccLinker<'a> {
         if let Some(plugin_path) = plugin_path {
             let mut arg = OsString::from("-plugin=");
             arg.push(plugin_path);
-            self.linker_arg(&arg);
+            self.link_arg(&arg);
         }
 
         let opt_level = match self.sess.opts.optimize {
@@ -292,9 +375,9 @@ impl<'a> GccLinker<'a> {
         };
 
         if let Some(path) = &self.sess.opts.unstable_opts.profile_sample_use {
-            self.linker_arg(&format!("-plugin-opt=sample-profile={}", path.display()));
+            self.link_arg(&format!("-plugin-opt=sample-profile={}", path.display()));
         };
-        self.linker_args(&[
+        self.link_args(&[
             &format!("-plugin-opt={opt_level}"),
             &format!("-plugin-opt=mcpu={}", self.target_cpu),
         ]);
@@ -304,10 +387,10 @@ impl<'a> GccLinker<'a> {
         // On mac we need to tell the linker to let this library be rpathed
         if self.sess.target.is_like_osx {
             if !self.is_ld {
-                self.cmd.arg("-dynamiclib");
+                self.cc_arg("-dynamiclib");
             }
 
-            self.linker_arg("-dylib");
+            self.link_arg("-dylib");
 
             // Note that the `osx_rpath_install_name` option here is a hack
             // purely to support rustbuild right now, we should get a more
@@ -316,10 +399,10 @@ impl<'a> GccLinker<'a> {
             if self.sess.opts.cg.rpath || self.sess.opts.unstable_opts.osx_rpath_install_name {
                 let mut rpath = OsString::from("@rpath/");
                 rpath.push(out_filename.file_name().unwrap());
-                self.linker_args(&[OsString::from("-install_name"), rpath]);
+                self.link_arg("-install_name").link_arg(rpath);
             }
         } else {
-            self.cmd.arg("-shared");
+            self.link_or_cc_arg("-shared");
             if self.sess.target.is_like_windows {
                 // The output filename already contains `dll_suffix` so
                 // the resulting import library will have a name in the
@@ -336,7 +419,7 @@ impl<'a> GccLinker<'a> {
                 if let Some(implib_name) = implib_name {
                     let implib = out_filename.parent().map(|dir| dir.join(&implib_name));
                     if let Some(implib) = implib {
-                        self.linker_arg(&format!("--out-implib={}", (*implib).to_str().unwrap()));
+                        self.link_arg(&format!("--out-implib={}", (*implib).to_str().unwrap()));
                     }
                 }
             }
@@ -345,76 +428,56 @@ impl<'a> GccLinker<'a> {
 }
 
 impl<'a> Linker for GccLinker<'a> {
-    /// Passes a series of arguments directly to the linker.
-    ///
-    /// When the linker is ld-like, the arguments are simply appended to the command. When the
-    /// linker is not ld-like such as when using a compiler as a linker, the arguments are joined by
-    /// commas to form an argument that is then prepended with `-Wl`. In this situation, only a
-    /// single argument is appended to the command to ensure that the order of the arguments is
-    /// preserved by the compiler.
-    fn linker_args(&mut self, args: &[&OsStr], verbatim: bool) {
-        if self.is_ld || verbatim {
-            args.into_iter().for_each(|a| {
-                self.cmd.arg(a);
-            });
-        } else {
-            if !args.is_empty() {
-                let mut s = OsString::from("-Wl");
-                for a in args {
-                    s.push(",");
-                    s.push(a);
-                }
-                self.cmd.arg(s);
-            }
-        }
-    }
-
     fn cmd(&mut self) -> &mut Command {
         &mut self.cmd
     }
 
+    fn is_cc(&self) -> bool {
+        !self.is_ld
+    }
+
     fn set_output_kind(&mut self, output_kind: LinkOutputKind, out_filename: &Path) {
         match output_kind {
             LinkOutputKind::DynamicNoPicExe => {
                 if !self.is_ld && self.is_gnu {
-                    self.cmd.arg("-no-pie");
+                    self.cc_arg("-no-pie");
                 }
             }
             LinkOutputKind::DynamicPicExe => {
                 // noop on windows w/ gcc & ld, error w/ lld
                 if !self.sess.target.is_like_windows {
                     // `-pie` works for both gcc wrapper and ld.
-                    self.cmd.arg("-pie");
+                    self.link_or_cc_arg("-pie");
                 }
             }
             LinkOutputKind::StaticNoPicExe => {
                 // `-static` works for both gcc wrapper and ld.
-                self.cmd.arg("-static");
+                self.link_or_cc_arg("-static");
                 if !self.is_ld && self.is_gnu {
-                    self.cmd.arg("-no-pie");
+                    self.cc_arg("-no-pie");
                 }
             }
             LinkOutputKind::StaticPicExe => {
                 if !self.is_ld {
                     // Note that combination `-static -pie` doesn't work as expected
                     // for the gcc wrapper, `-static` in that case suppresses `-pie`.
-                    self.cmd.arg("-static-pie");
+                    self.cc_arg("-static-pie");
                 } else {
                     // `--no-dynamic-linker` and `-z text` are not strictly necessary for producing
                     // a static pie, but currently passed because gcc and clang pass them.
                     // The former suppresses the `INTERP` ELF header specifying dynamic linker,
                     // which is otherwise implicitly injected by ld (but not lld).
                     // The latter doesn't change anything, only ensures that everything is pic.
-                    self.cmd.args(&["-static", "-pie", "--no-dynamic-linker", "-z", "text"]);
+                    self.link_args(&["-static", "-pie", "--no-dynamic-linker", "-z", "text"]);
                 }
             }
             LinkOutputKind::DynamicDylib => self.build_dylib(out_filename),
             LinkOutputKind::StaticDylib => {
-                self.cmd.arg("-static");
+                self.link_or_cc_arg("-static");
                 self.build_dylib(out_filename);
             }
             LinkOutputKind::WasiReactorExe => {
-                self.linker_args(&["--entry", "_initialize"]);
+                self.link_args(&["--entry", "_initialize"]);
             }
         }
         // VxWorks compiler driver introduced `--static-crt` flag specifically for rustc,
@@ -430,7 +493,7 @@ impl<'a> Linker for GccLinker<'a> {
                     | LinkOutputKind::StaticDylib
             )
         {
-            self.cmd.arg("--static-crt");
+            self.cc_arg("--static-crt");
         }
     }
 
@@ -450,18 +513,18 @@ impl<'a> Linker for GccLinker<'a> {
                 // but we have no way to detect that here.
                 self.sess.dcx().emit_warn(errors::Ld64UnimplementedModifier);
             } else if self.is_gnu && !self.sess.target.is_like_windows {
-                self.linker_arg("--no-as-needed");
+                self.link_arg("--no-as-needed");
             } else {
                 self.sess.dcx().emit_warn(errors::LinkerUnsupportedModifier);
             }
         }
         self.hint_dynamic();
-        self.cmd.arg(format!("-l{}{name}", if verbatim && self.is_gnu { ":" } else { "" },));
+        self.link_or_cc_arg(format!("-l{}{name}", if verbatim && self.is_gnu { ":" } else { "" },));
         if !as_needed {
             if self.sess.target.is_like_osx {
                 // See above FIXME comment
             } else if self.is_gnu && !self.sess.target.is_like_windows {
-                self.linker_arg("--as-needed");
+                self.link_arg("--as-needed");
             }
         }
     }
@@ -471,63 +534,51 @@ impl<'a> Linker for GccLinker<'a> {
         if !as_needed {
             // FIXME(81490): ld64 as of macOS 11 supports the -needed_framework
             // flag but we have no way to detect that here.
-            // self.cmd.arg("-needed_framework").arg(name);
+            // self.link_or_cc_arg("-needed_framework").link_or_cc_arg(name);
             self.sess.dcx().emit_warn(errors::Ld64UnimplementedModifier);
         }
-        self.cmd.arg("-framework").arg(name);
+        self.link_or_cc_args(&["-framework", name]);
     }
 
     fn link_staticlib_by_name(&mut self, name: &str, verbatim: bool, whole_archive: bool) {
         self.hint_static();
         let colon = if verbatim && self.is_gnu { ":" } else { "" };
         if !whole_archive {
-            self.cmd.arg(format!("-l{colon}{name}"));
+            self.link_or_cc_arg(format!("-l{colon}{name}"));
         } else if self.sess.target.is_like_osx {
             // -force_load is the macOS equivalent of --whole-archive, but it
             // involves passing the full path to the library to link.
-            self.linker_arg("-force_load");
-            self.linker_arg(find_native_static_library(name, verbatim, self.sess));
+            self.link_arg("-force_load");
+            self.link_arg(find_native_static_library(name, verbatim, self.sess));
         } else {
-            self.linker_arg("--whole-archive");
-            self.cmd.arg(format!("-l{colon}{name}"));
-            self.linker_arg("--no-whole-archive");
+            self.link_arg("--whole-archive")
+                .link_or_cc_arg(format!("-l{colon}{name}"))
+                .link_arg("--no-whole-archive");
         }
     }
 
     fn link_staticlib_by_path(&mut self, path: &Path, whole_archive: bool) {
         self.hint_static();
         if !whole_archive {
-            self.cmd.arg(path);
+            self.link_or_cc_arg(path);
         } else if self.sess.target.is_like_osx {
-            self.linker_arg("-force_load");
-            self.linker_arg(path);
+            self.link_arg("-force_load").link_arg(path);
         } else {
-            self.linker_arg("--whole-archive");
-            self.linker_arg(path);
-            self.linker_arg("--no-whole-archive");
+            self.link_arg("--whole-archive").link_arg(path).link_arg("--no-whole-archive");
         }
     }
 
-    fn include_path(&mut self, path: &Path) {
-        self.cmd.arg("-L").arg(path);
-    }
     fn framework_path(&mut self, path: &Path) {
-        self.cmd.arg("-F").arg(path);
-    }
-    fn output_filename(&mut self, path: &Path) {
-        self.cmd.arg("-o").arg(path);
-    }
-    fn add_object(&mut self, path: &Path) {
-        self.cmd.arg(path);
+        self.link_or_cc_arg("-F").link_or_cc_arg(path);
     }
     fn full_relro(&mut self) {
-        self.linker_args(&["-z", "relro", "-z", "now"]);
+        self.link_args(&["-z", "relro", "-z", "now"]);
     }
     fn partial_relro(&mut self) {
-        self.linker_args(&["-z", "relro"]);
+        self.link_args(&["-z", "relro"]);
     }
     fn no_relro(&mut self) {
-        self.linker_args(&["-z", "norelro"]);
+        self.link_args(&["-z", "norelro"]);
     }
 
     fn gc_sections(&mut self, keep_metadata: bool) {
@@ -546,7 +597,7 @@ impl<'a> Linker for GccLinker<'a> {
         // for partial linking when using multiple codegen units (-r). So we
         // insert it here.
         if self.sess.target.is_like_osx {
-            self.linker_arg("-dead_strip");
+            self.link_arg("-dead_strip");
 
         // If we're building a dylib, we don't use --gc-sections because LLVM
         // has already done the best it can do, and we also don't want to
@@ -554,13 +605,13 @@ impl<'a> Linker for GccLinker<'a> {
         // --gc-sections drops the size of hello world from 1.8MB to 597K, a 67%
         // reduction.
         } else if (self.is_gnu || self.sess.target.is_like_wasm) && !keep_metadata {
-            self.linker_arg("--gc-sections");
+            self.link_arg("--gc-sections");
         }
     }
 
     fn no_gc_sections(&mut self) {
         if self.is_gnu || self.sess.target.is_like_wasm {
-            self.linker_arg("--no-gc-sections");
+            self.link_arg("--no-gc-sections");
         }
     }
 
@@ -574,7 +625,7 @@ impl<'a> Linker for GccLinker<'a> {
         if self.sess.opts.optimize == config::OptLevel::Default
             || self.sess.opts.optimize == config::OptLevel::Aggressive
         {
-            self.linker_arg("-O1");
+            self.link_arg("-O1");
         }
     }
 
@@ -594,8 +645,7 @@ impl<'a> Linker for GccLinker<'a> {
         //
         // Though it may be worth to try to revert those changes upstream, since
         // the overhead of the initialization should be minor.
-        self.cmd.arg("-u");
-        self.cmd.arg("__llvm_profile_runtime");
+        self.link_or_cc_args(&["-u", "__llvm_profile_runtime"]);
     }
 
     fn control_flow_guard(&mut self) {}
@@ -616,33 +666,33 @@ impl<'a> Linker for GccLinker<'a> {
                 // The --strip-debug case is handled by running an external
                 // `strip` utility as a separate step after linking.
                 if !self.sess.target.is_like_solaris {
-                    self.linker_arg("--strip-debug");
+                    self.link_arg("--strip-debug");
                 }
             }
             Strip::Symbols => {
-                self.linker_arg("--strip-all");
+                self.link_arg("--strip-all");
             }
         }
         match self.sess.opts.unstable_opts.debuginfo_compression {
             config::DebugInfoCompression::None => {}
             config::DebugInfoCompression::Zlib => {
-                self.linker_arg("--compress-debug-sections=zlib");
+                self.link_arg("--compress-debug-sections=zlib");
             }
             config::DebugInfoCompression::Zstd => {
-                self.linker_arg("--compress-debug-sections=zstd");
+                self.link_arg("--compress-debug-sections=zstd");
             }
         }
     }
 
     fn no_crt_objects(&mut self) {
         if !self.is_ld {
-            self.cmd.arg("-nostartfiles");
+            self.cc_arg("-nostartfiles");
         }
     }
 
     fn no_default_libraries(&mut self) {
         if !self.is_ld {
-            self.cmd.arg("-nodefaultlibs");
+            self.cc_arg("-nodefaultlibs");
         }
     }
 
@@ -718,24 +768,22 @@ impl<'a> Linker for GccLinker<'a> {
         }
 
         if self.sess.target.is_like_osx {
-            self.linker_args(&[OsString::from("-exported_symbols_list"), path.into()]);
+            self.link_arg("-exported_symbols_list").link_arg(path);
         } else if self.sess.target.is_like_solaris {
-            self.linker_args(&[OsString::from("-M"), path.into()]);
+            self.link_arg("-M").link_arg(path);
         } else {
             if is_windows {
-                self.linker_arg(path);
+                self.link_arg(path);
             } else {
                 let mut arg = OsString::from("--version-script=");
                 arg.push(path);
-                self.linker_arg(arg);
-                self.linker_arg("--no-undefined-version");
+                self.link_arg(arg).link_arg("--no-undefined-version");
             }
         }
     }
 
     fn subsystem(&mut self, subsystem: &str) {
-        self.linker_arg("--subsystem");
-        self.linker_arg(&subsystem);
+        self.link_args(&["--subsystem", subsystem]);
     }
 
     fn reset_per_library_state(&mut self) {
@@ -760,23 +808,23 @@ impl<'a> Linker for GccLinker<'a> {
     // Some versions of `gcc` add it implicitly, some (e.g. `musl-gcc`) don't,
     // so we just always add it.
     fn add_eh_frame_header(&mut self) {
-        self.linker_arg("--eh-frame-hdr");
+        self.link_arg("--eh-frame-hdr");
     }
 
     fn add_no_exec(&mut self) {
         if self.sess.target.is_like_windows {
-            self.linker_arg("--nxcompat");
+            self.link_arg("--nxcompat");
         } else if self.is_gnu {
-            self.linker_args(&["-z", "noexecstack"]);
+            self.link_args(&["-z", "noexecstack"]);
         }
     }
 
     fn add_as_needed(&mut self) {
         if self.is_gnu && !self.sess.target.is_like_windows {
-            self.linker_arg("--as-needed");
+            self.link_arg("--as-needed");
         } else if self.sess.target.is_like_solaris {
             // -z ignore is the Solaris equivalent to the GNU ld --as-needed option
-            self.linker_args(&["-z", "ignore"]);
+            self.link_args(&["-z", "ignore"]);
         }
     }
 }
@@ -798,10 +846,10 @@ impl<'a> Linker for MsvcLinker<'a> {
             | LinkOutputKind::StaticNoPicExe
             | LinkOutputKind::StaticPicExe => {}
             LinkOutputKind::DynamicDylib | LinkOutputKind::StaticDylib => {
-                self.cmd.arg("/DLL");
+                self.link_arg("/DLL");
                 let mut arg: OsString = "/IMPLIB:".into();
                 arg.push(out_filename.with_extension("dll.lib"));
-                self.cmd.arg(arg);
+                self.link_arg(arg);
             }
             LinkOutputKind::WasiReactorExe => {
                 panic!("can't link as reactor on non-wasi target");
@@ -810,44 +858,40 @@ impl<'a> Linker for MsvcLinker<'a> {
     }
 
     fn link_dylib_by_name(&mut self, name: &str, verbatim: bool, _as_needed: bool) {
-        self.cmd.arg(format!("{}{}", name, if verbatim { "" } else { ".lib" }));
+        self.link_arg(format!("{}{}", name, if verbatim { "" } else { ".lib" }));
     }
 
     fn link_staticlib_by_name(&mut self, name: &str, verbatim: bool, whole_archive: bool) {
         let prefix = if whole_archive { "/WHOLEARCHIVE:" } else { "" };
         let suffix = if verbatim { "" } else { ".lib" };
-        self.cmd.arg(format!("{prefix}{name}{suffix}"));
+        self.link_arg(format!("{prefix}{name}{suffix}"));
     }
 
     fn link_staticlib_by_path(&mut self, path: &Path, whole_archive: bool) {
         if !whole_archive {
-            self.cmd.arg(path);
+            self.link_arg(path);
         } else {
             let mut arg = OsString::from("/WHOLEARCHIVE:");
             arg.push(path);
-            self.cmd.arg(arg);
+            self.link_arg(arg);
         }
     }
 
-    fn add_object(&mut self, path: &Path) {
-        self.cmd.arg(path);
-    }
-
     fn gc_sections(&mut self, _keep_metadata: bool) {
         // MSVC's ICF (Identical COMDAT Folding) link optimization is
         // slow for Rust and thus we disable it by default when not in
         // optimization build.
         if self.sess.opts.optimize != config::OptLevel::No {
-            self.cmd.arg("/OPT:REF,ICF");
+            self.link_arg("/OPT:REF,ICF");
         } else {
             // It is necessary to specify NOICF here, because /OPT:REF
             // implies ICF by default.
-            self.cmd.arg("/OPT:REF,NOICF");
+            self.link_arg("/OPT:REF,NOICF");
         }
     }
 
     fn no_gc_sections(&mut self) {
-        self.cmd.arg("/OPT:NOREF,NOICF");
+        self.link_arg("/OPT:NOREF,NOICF");
     }
 
     fn full_relro(&mut self) {
@@ -867,23 +911,19 @@ impl<'a> Linker for MsvcLinker<'a> {
     }
 
     fn no_default_libraries(&mut self) {
-        self.cmd.arg("/NODEFAULTLIB");
+        self.link_arg("/NODEFAULTLIB");
     }
 
     fn include_path(&mut self, path: &Path) {
         let mut arg = OsString::from("/LIBPATH:");
         arg.push(path);
-        self.cmd.arg(&arg);
+        self.link_arg(&arg);
     }
 
     fn output_filename(&mut self, path: &Path) {
         let mut arg = OsString::from("/OUT:");
         arg.push(path);
-        self.cmd.arg(&arg);
-    }
-
-    fn framework_path(&mut self, _path: &Path) {
-        bug!("frameworks are not supported on windows")
+        self.link_arg(&arg);
     }
 
     fn optimize(&mut self) {
@@ -895,19 +935,19 @@ impl<'a> Linker for MsvcLinker<'a> {
     }
 
     fn control_flow_guard(&mut self) {
-        self.cmd.arg("/guard:cf");
+        self.link_arg("/guard:cf");
     }
 
     fn ehcont_guard(&mut self) {
         if self.sess.target.pointer_width == 64 {
-            self.cmd.arg("/guard:ehcont");
+            self.link_arg("/guard:ehcont");
         }
     }
 
     fn debuginfo(&mut self, _strip: Strip, natvis_debugger_visualizers: &[PathBuf]) {
         // This will cause the Microsoft linker to generate a PDB file
         // from the CodeView line tables in the object files.
-        self.cmd.arg("/DEBUG");
+        self.link_arg("/DEBUG");
 
         // Default to emitting only the file name of the PDB file into
         // the binary instead of the full path. Emitting the full path
@@ -916,7 +956,7 @@ impl<'a> Linker for MsvcLinker<'a> {
         //
         // This default behavior can be overridden by explicitly passing
         // `-Clink-arg=/PDBALTPATH:...` to rustc.
-        self.cmd.arg("/PDBALTPATH:%_PDB%");
+        self.link_arg("/PDBALTPATH:%_PDB%");
 
         // This will cause the Microsoft linker to embed .natvis info into the PDB file
         let natvis_dir_path = self.sess.sysroot.join("lib\\rustlib\\etc");
@@ -928,7 +968,7 @@ impl<'a> Linker for MsvcLinker<'a> {
                         if path.extension() == Some("natvis".as_ref()) {
                             let mut arg = OsString::from("/NATVIS:");
                             arg.push(path);
-                            self.cmd.arg(arg);
+                            self.link_arg(arg);
                         }
                     }
                     Err(error) => {
@@ -942,7 +982,7 @@ impl<'a> Linker for MsvcLinker<'a> {
         for path in natvis_debugger_visualizers {
             let mut arg = OsString::from("/NATVIS:");
             arg.push(path);
-            self.cmd.arg(arg);
+            self.link_arg(arg);
         }
     }
 
@@ -986,13 +1026,13 @@ impl<'a> Linker for MsvcLinker<'a> {
         }
         let mut arg = OsString::from("/DEF:");
         arg.push(path);
-        self.cmd.arg(&arg);
+        self.link_arg(&arg);
     }
 
     fn subsystem(&mut self, subsystem: &str) {
         // Note that previous passes of the compiler validated this subsystem,
         // so we just blindly pass it to the linker.
-        self.cmd.arg(&format!("/SUBSYSTEM:{subsystem}"));
+        self.link_arg(&format!("/SUBSYSTEM:{subsystem}"));
 
         // Windows has two subsystems we're interested in right now, the console
         // and windows subsystems. These both implicitly have different entry
@@ -1009,7 +1049,7 @@ impl<'a> Linker for MsvcLinker<'a> {
         //
         // For more information see RFC #1665
         if subsystem == "windows" {
-            self.cmd.arg("/ENTRY:mainCRTStartup");
+            self.link_arg("/ENTRY:mainCRTStartup");
         }
     }
 
@@ -1018,7 +1058,7 @@ impl<'a> Linker for MsvcLinker<'a> {
     }
 
     fn add_no_exec(&mut self) {
-        self.cmd.arg("/NXCOMPAT");
+        self.link_arg("/NXCOMPAT");
     }
 }
 
@@ -1032,31 +1072,23 @@ impl<'a> Linker for EmLinker<'a> {
         &mut self.cmd
     }
 
+    fn is_cc(&self) -> bool {
+        true
+    }
+
     fn set_output_kind(&mut self, _output_kind: LinkOutputKind, _out_filename: &Path) {}
 
     fn link_dylib_by_name(&mut self, name: &str, _verbatim: bool, _as_needed: bool) {
         // Emscripten always links statically
-        self.cmd.arg("-l").arg(name);
+        self.link_or_cc_args(&["-l", name]);
     }
 
     fn link_staticlib_by_name(&mut self, name: &str, _verbatim: bool, _whole_archive: bool) {
-        self.cmd.arg("-l").arg(name);
+        self.link_or_cc_args(&["-l", name]);
     }
 
     fn link_staticlib_by_path(&mut self, path: &Path, _whole_archive: bool) {
-        self.cmd.arg(path);
-    }
-
-    fn include_path(&mut self, path: &Path) {
-        self.cmd.arg("-L").arg(path);
-    }
-
-    fn output_filename(&mut self, path: &Path) {
-        self.cmd.arg("-o").arg(path);
-    }
-
-    fn add_object(&mut self, path: &Path) {
-        self.cmd.arg(path);
+        self.link_or_cc_arg(path);
     }
 
     fn full_relro(&mut self) {
@@ -1071,10 +1103,6 @@ impl<'a> Linker for EmLinker<'a> {
         // noop
     }
 
-    fn framework_path(&mut self, _path: &Path) {
-        bug!("frameworks are not supported on Emscripten")
-    }
-
     fn gc_sections(&mut self, _keep_metadata: bool) {
         // noop
     }
@@ -1085,7 +1113,7 @@ impl<'a> Linker for EmLinker<'a> {
 
     fn optimize(&mut self) {
         // Emscripten performs own optimizations
-        self.cmd.arg(match self.sess.opts.optimize {
+        self.cc_arg(match self.sess.opts.optimize {
             OptLevel::No => "-O0",
             OptLevel::Less => "-O1",
             OptLevel::Default => "-O2",
@@ -1106,7 +1134,7 @@ impl<'a> Linker for EmLinker<'a> {
     fn debuginfo(&mut self, _strip: Strip, _: &[PathBuf]) {
         // Preserve names or generate source maps depending on debug info
         // For more information see https://emscripten.org/docs/tools_reference/emcc.html#emcc-g
-        self.cmd.arg(match self.sess.opts.debuginfo {
+        self.cc_arg(match self.sess.opts.debuginfo {
             DebugInfo::None => "-g0",
             DebugInfo::Limited | DebugInfo::LineTablesOnly | DebugInfo::LineDirectivesOnly => {
                 "--profiling-funcs"
@@ -1118,13 +1146,13 @@ impl<'a> Linker for EmLinker<'a> {
     fn no_crt_objects(&mut self) {}
 
     fn no_default_libraries(&mut self) {
-        self.cmd.arg("-nodefaultlibs");
+        self.cc_arg("-nodefaultlibs");
     }
 
     fn export_symbols(&mut self, _tmpdir: &Path, _crate_type: CrateType, symbols: &[String]) {
         debug!("EXPORTED SYMBOLS:");
 
-        self.cmd.arg("-s");
+        self.cc_arg("-s");
 
         let mut arg = OsString::from("EXPORTED_FUNCTIONS=");
         let encoded = serde_json::to_string(
@@ -1135,7 +1163,7 @@ impl<'a> Linker for EmLinker<'a> {
 
         arg.push(encoded);
 
-        self.cmd.arg(arg);
+        self.cc_arg(arg);
     }
 
     fn subsystem(&mut self, _subsystem: &str) {
@@ -1153,7 +1181,7 @@ pub struct WasmLd<'a> {
 }
 
 impl<'a> WasmLd<'a> {
-    fn new(mut cmd: Command, sess: &'a Session) -> WasmLd<'a> {
+    fn new(cmd: Command, sess: &'a Session) -> WasmLd<'a> {
         // If the atomics feature is enabled for wasm then we need a whole bunch
         // of flags:
         //
@@ -1172,18 +1200,19 @@ impl<'a> WasmLd<'a> {
         // On wasm32-unknown-unknown, we also export symbols for glue code to use:
         //    * `--export=*tls*` - when `#[thread_local]` symbols are used these
         //      symbols are how the TLS segments are initialized and configured.
+        let mut wasm_ld = WasmLd { cmd, sess };
         if sess.target_features.contains(&sym::atomics) {
-            cmd.arg("--shared-memory");
-            cmd.arg("--max-memory=1073741824");
-            cmd.arg("--import-memory");
+            wasm_ld.link_args(&["--shared-memory", "--max-memory=1073741824", "--import-memory"]);
             if sess.target.os == "unknown" {
-                cmd.arg("--export=__wasm_init_tls");
-                cmd.arg("--export=__tls_size");
-                cmd.arg("--export=__tls_align");
-                cmd.arg("--export=__tls_base");
+                wasm_ld.link_args(&[
+                    "--export=__wasm_init_tls",
+                    "--export=__tls_size",
+                    "--export=__tls_align",
+                    "--export=__tls_base",
+                ]);
             }
         }
-        WasmLd { cmd, sess }
+        wasm_ld
     }
 }
 
@@ -1199,51 +1228,36 @@ impl<'a> Linker for WasmLd<'a> {
             | LinkOutputKind::StaticNoPicExe
             | LinkOutputKind::StaticPicExe => {}
             LinkOutputKind::DynamicDylib | LinkOutputKind::StaticDylib => {
-                self.cmd.arg("--no-entry");
+                self.link_arg("--no-entry");
             }
             LinkOutputKind::WasiReactorExe => {
-                self.cmd.arg("--entry");
-                self.cmd.arg("_initialize");
+                self.link_args(&["--entry", "_initialize"]);
             }
         }
     }
 
     fn link_dylib_by_name(&mut self, name: &str, _verbatim: bool, _as_needed: bool) {
-        self.cmd.arg("-l").arg(name);
+        self.link_or_cc_args(&["-l", name]);
     }
 
     fn link_staticlib_by_name(&mut self, name: &str, _verbatim: bool, whole_archive: bool) {
         if !whole_archive {
-            self.cmd.arg("-l").arg(name);
+            self.link_or_cc_args(&["-l", name]);
         } else {
-            self.cmd.arg("--whole-archive").arg("-l").arg(name).arg("--no-whole-archive");
+            self.link_arg("--whole-archive")
+                .link_or_cc_args(&["-l", name])
+                .link_arg("--no-whole-archive");
         }
     }
 
     fn link_staticlib_by_path(&mut self, path: &Path, whole_archive: bool) {
         if !whole_archive {
-            self.cmd.arg(path);
+            self.link_or_cc_arg(path);
         } else {
-            self.cmd.arg("--whole-archive").arg(path).arg("--no-whole-archive");
+            self.link_arg("--whole-archive").link_or_cc_arg(path).link_arg("--no-whole-archive");
         }
     }
 
-    fn include_path(&mut self, path: &Path) {
-        self.cmd.arg("-L").arg(path);
-    }
-
-    fn framework_path(&mut self, _path: &Path) {
-        panic!("frameworks not supported")
-    }
-
-    fn output_filename(&mut self, path: &Path) {
-        self.cmd.arg("-o").arg(path);
-    }
-
-    fn add_object(&mut self, path: &Path) {
-        self.cmd.arg(path);
-    }
-
     fn full_relro(&mut self) {}
 
     fn partial_relro(&mut self) {}
@@ -1251,17 +1265,17 @@ impl<'a> Linker for WasmLd<'a> {
     fn no_relro(&mut self) {}
 
     fn gc_sections(&mut self, _keep_metadata: bool) {
-        self.cmd.arg("--gc-sections");
+        self.link_arg("--gc-sections");
     }
 
     fn no_gc_sections(&mut self) {
-        self.cmd.arg("--no-gc-sections");
+        self.link_arg("--no-gc-sections");
     }
 
     fn optimize(&mut self) {
         // The -O flag is, as of late 2023, only used for merging of strings and debuginfo, and
         // only differentiates -O0 and -O1. It does not apply to LTO.
-        self.cmd.arg(match self.sess.opts.optimize {
+        self.link_arg(match self.sess.opts.optimize {
             OptLevel::No => "-O0",
             OptLevel::Less => "-O1",
             OptLevel::Default => "-O2",
@@ -1279,10 +1293,10 @@ impl<'a> Linker for WasmLd<'a> {
         match strip {
             Strip::None => {}
             Strip::Debuginfo => {
-                self.cmd.arg("--strip-debug");
+                self.link_arg("--strip-debug");
             }
             Strip::Symbols => {
-                self.cmd.arg("--strip-all");
+                self.link_arg("--strip-all");
             }
         }
     }
@@ -1297,7 +1311,7 @@ impl<'a> Linker for WasmLd<'a> {
 
     fn export_symbols(&mut self, _tmpdir: &Path, _crate_type: CrateType, symbols: &[String]) {
         for sym in symbols {
-            self.cmd.arg("--export").arg(&sym);
+            self.link_args(&["--export", sym]);
         }
 
         // LLD will hide these otherwise-internal symbols since it only exports
@@ -1305,8 +1319,7 @@ impl<'a> Linker for WasmLd<'a> {
         // others. Various bits and pieces of wasm32-unknown-unknown tooling use
         // this, so be sure these symbols make their way out of the linker as well.
         if self.sess.target.os == "unknown" {
-            self.cmd.arg("--export=__heap_base");
-            self.cmd.arg("--export=__data_end");
+            self.link_args(&["--export=__heap_base", "--export=__data_end"]);
         }
     }
 
@@ -1337,7 +1350,7 @@ impl<'a> WasmLd<'a> {
             // wasm-ld only handles integer LTO opt levels. Use O2
             config::OptLevel::Size | config::OptLevel::SizeMin => "O2",
         };
-        self.cmd.arg(&format!("--lto-{opt_level}"));
+        self.link_arg(&format!("--lto-{opt_level}"));
     }
 }
 
@@ -1362,56 +1375,43 @@ impl<'a> Linker for L4Bender<'a> {
     fn link_staticlib_by_name(&mut self, name: &str, _verbatim: bool, whole_archive: bool) {
         self.hint_static();
         if !whole_archive {
-            self.cmd.arg(format!("-PC{name}"));
+            self.link_arg(format!("-PC{name}"));
         } else {
-            self.cmd.arg("--whole-archive").arg(format!("-l{name}")).arg("--no-whole-archive");
+            self.link_arg("--whole-archive")
+                .link_or_cc_arg(format!("-l{name}"))
+                .link_arg("--no-whole-archive");
         }
     }
 
     fn link_staticlib_by_path(&mut self, path: &Path, whole_archive: bool) {
         self.hint_static();
         if !whole_archive {
-            self.cmd.arg(path);
+            self.link_or_cc_arg(path);
         } else {
-            self.cmd.arg("--whole-archive").arg(path).arg("--no-whole-archive");
+            self.link_arg("--whole-archive").link_or_cc_arg(path).link_arg("--no-whole-archive");
         }
     }
 
-    fn include_path(&mut self, path: &Path) {
-        self.cmd.arg("-L").arg(path);
-    }
-    fn framework_path(&mut self, _: &Path) {
-        bug!("frameworks are not supported on L4Re");
-    }
-    fn output_filename(&mut self, path: &Path) {
-        self.cmd.arg("-o").arg(path);
-    }
-
-    fn add_object(&mut self, path: &Path) {
-        self.cmd.arg(path);
-    }
-
     fn full_relro(&mut self) {
-        self.cmd.arg("-z").arg("relro");
-        self.cmd.arg("-z").arg("now");
+        self.link_args(&["-z", "relro", "-z", "now"]);
     }
 
     fn partial_relro(&mut self) {
-        self.cmd.arg("-z").arg("relro");
+        self.link_args(&["-z", "relro"]);
     }
 
     fn no_relro(&mut self) {
-        self.cmd.arg("-z").arg("norelro");
+        self.link_args(&["-z", "norelro"]);
     }
 
     fn gc_sections(&mut self, keep_metadata: bool) {
         if !keep_metadata {
-            self.cmd.arg("--gc-sections");
+            self.link_arg("--gc-sections");
         }
     }
 
     fn no_gc_sections(&mut self) {
-        self.cmd.arg("--no-gc-sections");
+        self.link_arg("--no-gc-sections");
     }
 
     fn optimize(&mut self) {
@@ -1420,7 +1420,7 @@ impl<'a> Linker for L4Bender<'a> {
         if self.sess.opts.optimize == config::OptLevel::Default
             || self.sess.opts.optimize == config::OptLevel::Aggressive
         {
-            self.cmd.arg("-O1");
+            self.link_arg("-O1");
         }
     }
 
@@ -1430,16 +1430,16 @@ impl<'a> Linker for L4Bender<'a> {
         match strip {
             Strip::None => {}
             Strip::Debuginfo => {
-                self.cmd().arg("--strip-debug");
+                self.link_arg("--strip-debug");
             }
             Strip::Symbols => {
-                self.cmd().arg("--strip-all");
+                self.link_arg("--strip-all");
             }
         }
     }
 
     fn no_default_libraries(&mut self) {
-        self.cmd.arg("-nostdlib");
+        self.cc_arg("-nostdlib");
     }
 
     fn export_symbols(&mut self, _: &Path, _: CrateType, _: &[String]) {
@@ -1449,7 +1449,7 @@ impl<'a> Linker for L4Bender<'a> {
     }
 
     fn subsystem(&mut self, subsystem: &str) {
-        self.cmd.arg(&format!("--subsystem {subsystem}"));
+        self.link_arg(&format!("--subsystem {subsystem}"));
     }
 
     fn reset_per_library_state(&mut self) {
@@ -1467,12 +1467,12 @@ impl<'a> Linker for L4Bender<'a> {
 
 impl<'a> L4Bender<'a> {
     pub fn new(cmd: Command, sess: &'a Session) -> L4Bender<'a> {
-        L4Bender { cmd: cmd, sess: sess, hinted_static: false }
+        L4Bender { cmd, sess: sess, hinted_static: false }
     }
 
     fn hint_static(&mut self) {
         if !self.hinted_static {
-            self.cmd.arg("-static");
+            self.link_or_cc_arg("-static");
             self.hinted_static = true;
         }
     }
@@ -1487,29 +1487,28 @@ pub struct AixLinker<'a> {
 
 impl<'a> AixLinker<'a> {
     pub fn new(cmd: Command, sess: &'a Session) -> AixLinker<'a> {
-        AixLinker { cmd: cmd, sess: sess, hinted_static: None }
+        AixLinker { cmd, sess: sess, hinted_static: None }
     }
 
     fn hint_static(&mut self) {
         if self.hinted_static != Some(true) {
-            self.cmd.arg("-bstatic");
+            self.link_arg("-bstatic");
             self.hinted_static = Some(true);
         }
     }
 
     fn hint_dynamic(&mut self) {
         if self.hinted_static != Some(false) {
-            self.cmd.arg("-bdynamic");
+            self.link_arg("-bdynamic");
             self.hinted_static = Some(false);
         }
     }
 
     fn build_dylib(&mut self, _out_filename: &Path) {
-        self.cmd.arg("-bM:SRE");
-        self.cmd.arg("-bnoentry");
+        self.link_args(&["-bM:SRE", "-bnoentry"]);
         // FIXME: Use CreateExportList utility to create export list
         // and remove -bexpfull.
-        self.cmd.arg("-bexpfull");
+        self.link_arg("-bexpfull");
     }
 }
 
@@ -1534,47 +1533,31 @@ impl<'a> Linker for AixLinker<'a> {
 
     fn link_dylib_by_name(&mut self, name: &str, _verbatim: bool, _as_needed: bool) {
         self.hint_dynamic();
-        self.cmd.arg(format!("-l{name}"));
+        self.link_or_cc_arg(format!("-l{name}"));
     }
 
     fn link_staticlib_by_name(&mut self, name: &str, verbatim: bool, whole_archive: bool) {
         self.hint_static();
         if !whole_archive {
-            self.cmd.arg(format!("-l{name}"));
+            self.link_or_cc_arg(format!("-l{name}"));
         } else {
             let mut arg = OsString::from("-bkeepfile:");
             arg.push(find_native_static_library(name, verbatim, self.sess));
-            self.cmd.arg(arg);
+            self.link_or_cc_arg(arg);
         }
     }
 
     fn link_staticlib_by_path(&mut self, path: &Path, whole_archive: bool) {
         self.hint_static();
         if !whole_archive {
-            self.cmd.arg(path);
+            self.link_or_cc_arg(path);
         } else {
             let mut arg = OsString::from("-bkeepfile:");
             arg.push(path);
-            self.cmd.arg(arg);
+            self.link_arg(arg);
         }
     }
 
-    fn include_path(&mut self, path: &Path) {
-        self.cmd.arg("-L").arg(path);
-    }
-
-    fn framework_path(&mut self, _: &Path) {
-        bug!("frameworks are not supported on AIX");
-    }
-
-    fn output_filename(&mut self, path: &Path) {
-        self.cmd.arg("-o").arg(path);
-    }
-
-    fn add_object(&mut self, path: &Path) {
-        self.cmd.arg(path);
-    }
-
     fn full_relro(&mut self) {}
 
     fn partial_relro(&mut self) {}
@@ -1582,17 +1565,17 @@ impl<'a> Linker for AixLinker<'a> {
     fn no_relro(&mut self) {}
 
     fn gc_sections(&mut self, _keep_metadata: bool) {
-        self.cmd.arg("-bgc");
+        self.link_arg("-bgc");
     }
 
     fn no_gc_sections(&mut self) {
-        self.cmd.arg("-bnogc");
+        self.link_arg("-bnogc");
     }
 
     fn optimize(&mut self) {}
 
     fn pgo_gen(&mut self) {
-        self.cmd.arg("-bdbg:namedsects:ss");
+        self.link_arg("-bdbg:namedsects:ss");
     }
 
     fn control_flow_guard(&mut self) {}
@@ -1618,7 +1601,7 @@ impl<'a> Linker for AixLinker<'a> {
         if let Err(e) = res {
             self.sess.dcx().fatal(format!("failed to write export file: {e}"));
         }
-        self.cmd.arg(format!("-bE:{}", path.to_str().unwrap()));
+        self.link_arg(format!("-bE:{}", path.to_str().unwrap()));
     }
 
     fn subsystem(&mut self, _subsystem: &str) {}
@@ -1747,39 +1730,27 @@ impl<'a> Linker for PtxLinker<'a> {
     }
 
     fn link_staticlib_by_path(&mut self, path: &Path, _whole_archive: bool) {
-        self.cmd.arg("--rlib").arg(path);
-    }
-
-    fn include_path(&mut self, path: &Path) {
-        self.cmd.arg("-L").arg(path);
+        self.link_arg("--rlib").link_arg(path);
     }
 
     fn debuginfo(&mut self, _strip: Strip, _: &[PathBuf]) {
-        self.cmd.arg("--debug");
+        self.link_arg("--debug");
     }
 
     fn add_object(&mut self, path: &Path) {
-        self.cmd.arg("--bitcode").arg(path);
+        self.link_arg("--bitcode").link_arg(path);
     }
 
     fn optimize(&mut self) {
         match self.sess.lto() {
             Lto::Thin | Lto::Fat | Lto::ThinLocal => {
-                self.cmd.arg("-Olto");
+                self.link_arg("-Olto");
             }
 
             Lto::No => {}
         }
     }
 
-    fn output_filename(&mut self, path: &Path) {
-        self.cmd.arg("-o").arg(path);
-    }
-
-    fn framework_path(&mut self, _path: &Path) {
-        panic!("frameworks not supported")
-    }
-
     fn full_relro(&mut self) {}
 
     fn partial_relro(&mut self) {}
@@ -1829,19 +1800,11 @@ impl<'a> Linker for LlbcLinker<'a> {
     }
 
     fn link_staticlib_by_path(&mut self, path: &Path, _whole_archive: bool) {
-        self.cmd.arg(path);
-    }
-
-    fn include_path(&mut self, path: &Path) {
-        self.cmd.arg("-L").arg(path);
+        self.link_or_cc_arg(path);
     }
 
     fn debuginfo(&mut self, _strip: Strip, _: &[PathBuf]) {
-        self.cmd.arg("--debug");
-    }
-
-    fn add_object(&mut self, path: &Path) {
-        self.cmd.arg(path);
+        self.link_arg("--debug");
     }
 
     fn optimize(&mut self) {
@@ -1855,14 +1818,6 @@ impl<'a> Linker for LlbcLinker<'a> {
         };
     }
 
-    fn output_filename(&mut self, path: &Path) {
-        self.cmd.arg("-o").arg(path);
-    }
-
-    fn framework_path(&mut self, _path: &Path) {
-        panic!("frameworks not supported")
-    }
-
     fn full_relro(&mut self) {}
 
     fn partial_relro(&mut self) {}
@@ -1887,7 +1842,7 @@ impl<'a> Linker for LlbcLinker<'a> {
         match _crate_type {
             CrateType::Cdylib => {
                 for sym in symbols {
-                    self.cmd.arg("--export-symbol").arg(sym);
+                    self.link_args(&["--export-symbol", sym]);
                 }
             }
             _ => (),
@@ -1920,23 +1875,15 @@ impl<'a> Linker for BpfLinker<'a> {
     }
 
     fn link_staticlib_by_path(&mut self, path: &Path, _whole_archive: bool) {
-        self.cmd.arg(path);
-    }
-
-    fn include_path(&mut self, path: &Path) {
-        self.cmd.arg("-L").arg(path);
+        self.link_or_cc_arg(path);
     }
 
     fn debuginfo(&mut self, _strip: Strip, _: &[PathBuf]) {
-        self.cmd.arg("--debug");
-    }
-
-    fn add_object(&mut self, path: &Path) {
-        self.cmd.arg(path);
+        self.link_arg("--debug");
     }
 
     fn optimize(&mut self) {
-        self.cmd.arg(match self.sess.opts.optimize {
+        self.link_arg(match self.sess.opts.optimize {
             OptLevel::No => "-O0",
             OptLevel::Less => "-O1",
             OptLevel::Default => "-O2",
@@ -1946,14 +1893,6 @@ impl<'a> Linker for BpfLinker<'a> {
         });
     }
 
-    fn output_filename(&mut self, path: &Path) {
-        self.cmd.arg("-o").arg(path);
-    }
-
-    fn framework_path(&mut self, _path: &Path) {
-        panic!("frameworks not supported")
-    }
-
     fn full_relro(&mut self) {}
 
     fn partial_relro(&mut self) {}
@@ -1985,7 +1924,7 @@ impl<'a> Linker for BpfLinker<'a> {
         if let Err(error) = res {
             self.sess.dcx().emit_fatal(errors::SymbolFileWriteFailure { error });
         } else {
-            self.cmd.arg("--export-symbols").arg(&path);
+            self.link_arg("--export-symbols").link_arg(&path);
         }
     }
 
diff --git a/compiler/rustc_codegen_ssa/src/back/rpath.rs b/compiler/rustc_codegen_ssa/src/back/rpath.rs
index f499bbcf853..82070d4453b 100644
--- a/compiler/rustc_codegen_ssa/src/back/rpath.rs
+++ b/compiler/rustc_codegen_ssa/src/back/rpath.rs
@@ -9,16 +9,10 @@ pub struct RPathConfig<'a> {
     pub libs: &'a [&'a Path],
     pub out_filename: PathBuf,
     pub is_like_osx: bool,
-    pub has_rpath: bool,
     pub linker_is_gnu: bool,
 }
 
 pub fn get_rpath_flags(config: &RPathConfig<'_>) -> Vec<OsString> {
-    // No rpath on windows
-    if !config.has_rpath {
-        return Vec::new();
-    }
-
     debug!("preparing the RPATH!");
 
     let rpaths = get_rpaths(config);
diff --git a/compiler/rustc_codegen_ssa/src/back/rpath/tests.rs b/compiler/rustc_codegen_ssa/src/back/rpath/tests.rs
index 0de90a1036e..c620e92db1f 100644
--- a/compiler/rustc_codegen_ssa/src/back/rpath/tests.rs
+++ b/compiler/rustc_codegen_ssa/src/back/rpath/tests.rs
@@ -37,7 +37,6 @@ fn test_rpath_relative() {
     if cfg!(target_os = "macos") {
         let config = &mut RPathConfig {
             libs: &[],
-            has_rpath: true,
             is_like_osx: true,
             linker_is_gnu: false,
             out_filename: PathBuf::from("bin/rustc"),
@@ -48,7 +47,6 @@ fn test_rpath_relative() {
         let config = &mut RPathConfig {
             libs: &[],
             out_filename: PathBuf::from("bin/rustc"),
-            has_rpath: true,
             is_like_osx: false,
             linker_is_gnu: true,
         };
@@ -62,7 +60,6 @@ fn test_rpath_relative_issue_119571() {
     let config = &mut RPathConfig {
         libs: &[],
         out_filename: PathBuf::from("rustc"),
-        has_rpath: true,
         is_like_osx: false,
         linker_is_gnu: true,
     };
diff --git a/compiler/rustc_codegen_ssa/src/meth.rs b/compiler/rustc_codegen_ssa/src/meth.rs
index ddc6797388e..febc8ee2be2 100644
--- a/compiler/rustc_codegen_ssa/src/meth.rs
+++ b/compiler/rustc_codegen_ssa/src/meth.rs
@@ -133,6 +133,7 @@ pub fn get_vtable<'tcx, Cx: CodegenMethods<'tcx>>(
     let align = cx.data_layout().pointer_align.abi;
     let vtable = cx.static_addr_of(vtable_const, align, Some("vtable"));
 
+    cx.apply_vcall_visibility_metadata(ty, trait_ref, vtable);
     cx.create_vtable_debuginfo(ty, trait_ref, vtable);
     cx.vtables().borrow_mut().insert((ty, trait_ref), vtable);
     vtable
diff --git a/compiler/rustc_codegen_ssa/src/mir/block.rs b/compiler/rustc_codegen_ssa/src/mir/block.rs
index 57138d3b9db..b1c22faf1ae 100644
--- a/compiler/rustc_codegen_ssa/src/mir/block.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/block.rs
@@ -658,7 +658,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
         // with #[rustc_inherit_overflow_checks] and inlined from
         // another crate (mostly core::num generic/#[inline] fns),
         // while the current crate doesn't use overflow checks.
-        if !bx.cx().check_overflow() && msg.is_optional_overflow_check() {
+        if !bx.sess().overflow_checks() && msg.is_optional_overflow_check() {
             const_cond = Some(expected);
         }
 
@@ -751,7 +751,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
         &mut self,
         helper: &TerminatorCodegenHelper<'tcx>,
         bx: &mut Bx,
-        intrinsic: Option<ty::IntrinsicDef>,
+        intrinsic: ty::IntrinsicDef,
         instance: Option<Instance<'tcx>>,
         source_info: mir::SourceInfo,
         target: Option<mir::BasicBlock>,
@@ -761,8 +761,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
         // Emit a panic or a no-op for `assert_*` intrinsics.
         // These are intrinsics that compile to panics so that we can get a message
         // which mentions the offending type, even from a const context.
-        let panic_intrinsic = intrinsic.and_then(|i| ValidityRequirement::from_intrinsic(i.name));
-        if let Some(requirement) = panic_intrinsic {
+        if let Some(requirement) = ValidityRequirement::from_intrinsic(intrinsic.name) {
             let ty = instance.unwrap().args.type_at(0);
 
             let do_panic = !bx
@@ -869,12 +868,6 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
         let sig = callee.layout.ty.fn_sig(bx.tcx());
         let abi = sig.abi();
 
-        // Handle intrinsics old codegen wants Expr's for, ourselves.
-        let intrinsic = match def {
-            Some(ty::InstanceKind::Intrinsic(def_id)) => Some(bx.tcx().intrinsic(def_id).unwrap()),
-            _ => None,
-        };
-
         let extra_args = &args[sig.inputs().skip_binder().len()..];
         let extra_args = bx.tcx().mk_type_list_from_iter(extra_args.iter().map(|op_arg| {
             let op_ty = op_arg.node.ty(self.mir, bx.tcx());
@@ -886,50 +879,25 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             None => bx.fn_abi_of_fn_ptr(sig, extra_args),
         };
 
-        if let Some(merging_succ) = self.codegen_panic_intrinsic(
-            &helper,
-            bx,
-            intrinsic,
-            instance,
-            source_info,
-            target,
-            unwind,
-            mergeable_succ,
-        ) {
-            return merging_succ;
-        }
-
         // The arguments we'll be passing. Plus one to account for outptr, if used.
         let arg_count = fn_abi.args.len() + fn_abi.ret.is_indirect() as usize;
 
-        if matches!(intrinsic, Some(ty::IntrinsicDef { name: sym::caller_location, .. })) {
-            return if let Some(target) = target {
-                let location =
-                    self.get_caller_location(bx, mir::SourceInfo { span: fn_span, ..source_info });
-
-                let mut llargs = Vec::with_capacity(arg_count);
-                let ret_dest = self.make_return_dest(
+        let instance = match def {
+            Some(ty::InstanceKind::Intrinsic(def_id)) => {
+                let intrinsic = bx.tcx().intrinsic(def_id).unwrap();
+                if let Some(merging_succ) = self.codegen_panic_intrinsic(
+                    &helper,
                     bx,
-                    destination,
-                    &fn_abi.ret,
-                    &mut llargs,
                     intrinsic,
-                    Some(target),
-                );
-                assert_eq!(llargs, []);
-                if let ReturnDest::IndirectOperand(tmp, _) = ret_dest {
-                    location.val.store(bx, tmp);
+                    instance,
+                    source_info,
+                    target,
+                    unwind,
+                    mergeable_succ,
+                ) {
+                    return merging_succ;
                 }
-                self.store_return(bx, ret_dest, &fn_abi.ret, location.immediate());
-                helper.funclet_br(self, bx, target, mergeable_succ)
-            } else {
-                MergingSucc::False
-            };
-        }
 
-        let instance = match intrinsic {
-            None => instance,
-            Some(intrinsic) => {
                 let mut llargs = Vec::with_capacity(1);
                 let ret_dest = self.make_return_dest(
                     bx,
@@ -971,6 +939,18 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                     })
                     .collect();
 
+                if matches!(intrinsic, ty::IntrinsicDef { name: sym::caller_location, .. }) {
+                    let location = self
+                        .get_caller_location(bx, mir::SourceInfo { span: fn_span, ..source_info });
+
+                    assert_eq!(llargs, []);
+                    if let ReturnDest::IndirectOperand(tmp, _) = ret_dest {
+                        location.val.store(bx, tmp);
+                    }
+                    self.store_return(bx, ret_dest, &fn_abi.ret, location.immediate());
+                    return helper.funclet_br(self, bx, target.unwrap(), mergeable_succ);
+                }
+
                 let instance = *instance.as_ref().unwrap();
                 match Self::codegen_intrinsic_call(bx, instance, fn_abi, &args, dest, span) {
                     Ok(()) => {
@@ -997,6 +977,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                     }
                 }
             }
+            _ => instance,
         };
 
         let mut llargs = Vec::with_capacity(arg_count);
diff --git a/compiler/rustc_codegen_ssa/src/traits/backend.rs b/compiler/rustc_codegen_ssa/src/traits/backend.rs
index e8b9490d401..3770bd11cf9 100644
--- a/compiler/rustc_codegen_ssa/src/traits/backend.rs
+++ b/compiler/rustc_codegen_ssa/src/traits/backend.rs
@@ -22,8 +22,6 @@ use rustc_session::{
 use rustc_span::symbol::Symbol;
 use rustc_target::abi::call::FnAbi;
 
-use std::fmt;
-
 pub trait BackendTypes {
     type Value: CodegenObject;
     type Function: CodegenObject;
@@ -62,7 +60,7 @@ pub trait CodegenBackend {
     fn locale_resource(&self) -> &'static str;
 
     fn init(&self, _sess: &Session) {}
-    fn print(&self, _req: &PrintRequest, _out: &mut dyn PrintBackendInfo, _sess: &Session) {}
+    fn print(&self, _req: &PrintRequest, _out: &mut String, _sess: &Session) {}
     fn target_features(&self, _sess: &Session, _allow_unstable: bool) -> Vec<Symbol> {
         vec![]
     }
@@ -150,19 +148,3 @@ pub trait ExtraBackendMethods:
         std::thread::Builder::new().name(name).spawn(f)
     }
 }
-
-pub trait PrintBackendInfo {
-    fn infallible_write_fmt(&mut self, args: fmt::Arguments<'_>);
-}
-
-impl PrintBackendInfo for String {
-    fn infallible_write_fmt(&mut self, args: fmt::Arguments<'_>) {
-        fmt::Write::write_fmt(self, args).unwrap();
-    }
-}
-
-impl dyn PrintBackendInfo + '_ {
-    pub fn write_fmt(&mut self, args: fmt::Arguments<'_>) {
-        self.infallible_write_fmt(args);
-    }
-}
diff --git a/compiler/rustc_codegen_ssa/src/traits/consts.rs b/compiler/rustc_codegen_ssa/src/traits/consts.rs
index 8cb17a5b37a..3da732602c5 100644
--- a/compiler/rustc_codegen_ssa/src/traits/consts.rs
+++ b/compiler/rustc_codegen_ssa/src/traits/consts.rs
@@ -37,6 +37,5 @@ pub trait ConstMethods<'tcx>: BackendTypes {
 
     fn scalar_to_backend(&self, cv: Scalar, layout: abi::Scalar, llty: Self::Type) -> Self::Value;
 
-    fn const_bitcast(&self, val: Self::Value, ty: Self::Type) -> Self::Value;
     fn const_ptr_byte_offset(&self, val: Self::Value, offset: abi::Size) -> Self::Value;
 }
diff --git a/compiler/rustc_codegen_ssa/src/traits/misc.rs b/compiler/rustc_codegen_ssa/src/traits/misc.rs
index 04e2b8796c4..0ace28ed3ba 100644
--- a/compiler/rustc_codegen_ssa/src/traits/misc.rs
+++ b/compiler/rustc_codegen_ssa/src/traits/misc.rs
@@ -9,7 +9,13 @@ pub trait MiscMethods<'tcx>: BackendTypes {
     fn vtables(
         &self,
     ) -> &RefCell<FxHashMap<(Ty<'tcx>, Option<ty::PolyExistentialTraitRef<'tcx>>), Self::Value>>;
-    fn check_overflow(&self) -> bool;
+    fn apply_vcall_visibility_metadata(
+        &self,
+        _ty: Ty<'tcx>,
+        _poly_trait_ref: Option<ty::PolyExistentialTraitRef<'tcx>>,
+        _vtable: Self::Value,
+    ) {
+    }
     fn get_fn(&self, instance: Instance<'tcx>) -> Self::Function;
     fn get_fn_addr(&self, instance: Instance<'tcx>) -> Self::Value;
     fn eh_personality(&self) -> Self::Value;
diff --git a/compiler/rustc_codegen_ssa/src/traits/mod.rs b/compiler/rustc_codegen_ssa/src/traits/mod.rs
index 728c2bc8c49..8cb58bd4c70 100644
--- a/compiler/rustc_codegen_ssa/src/traits/mod.rs
+++ b/compiler/rustc_codegen_ssa/src/traits/mod.rs
@@ -30,9 +30,7 @@ mod write;
 
 pub use self::abi::AbiBuilderMethods;
 pub use self::asm::{AsmBuilderMethods, AsmMethods, GlobalAsmOperandRef, InlineAsmOperandRef};
-pub use self::backend::{
-    Backend, BackendTypes, CodegenBackend, ExtraBackendMethods, PrintBackendInfo,
-};
+pub use self::backend::{Backend, BackendTypes, CodegenBackend, ExtraBackendMethods};
 pub use self::builder::{BuilderMethods, OverflowOp};
 pub use self::consts::ConstMethods;
 pub use self::coverageinfo::CoverageInfoBuilderMethods;
diff --git a/compiler/rustc_codegen_ssa/src/traits/type_.rs b/compiler/rustc_codegen_ssa/src/traits/type_.rs
index 403f6a73277..b1bad6cfa6f 100644
--- a/compiler/rustc_codegen_ssa/src/traits/type_.rs
+++ b/compiler/rustc_codegen_ssa/src/traits/type_.rs
@@ -12,7 +12,6 @@ use rustc_target::abi::{AddressSpace, Float, Integer};
 // This depends on `Backend` and not `BackendTypes`, because consumers will probably want to use
 // `LayoutOf` or `HasTyCtxt`. This way, they don't have to add a constraint on it themselves.
 pub trait BaseTypeMethods<'tcx>: Backend<'tcx> {
-    fn type_i1(&self) -> Self::Type;
     fn type_i8(&self) -> Self::Type;
     fn type_i16(&self) -> Self::Type;
     fn type_i32(&self) -> Self::Type;
@@ -27,7 +26,6 @@ pub trait BaseTypeMethods<'tcx>: Backend<'tcx> {
 
     fn type_array(&self, ty: Self::Type, len: u64) -> Self::Type;
     fn type_func(&self, args: &[Self::Type], ret: Self::Type) -> Self::Type;
-    fn type_struct(&self, els: &[Self::Type], packed: bool) -> Self::Type;
     fn type_kind(&self, ty: Self::Type) -> TypeKind;
     fn type_ptr(&self) -> Self::Type;
     fn type_ptr_ext(&self, address_space: AddressSpace) -> Self::Type;
@@ -115,8 +113,8 @@ pub trait LayoutTypeMethods<'tcx>: Backend<'tcx> {
     /// The backend type used for a rust type when it's in an SSA register.
     ///
     /// For nearly all types this is the same as the [`Self::backend_type`], however
-    /// `bool` (and other `0`-or-`1` values) are kept as [`BaseTypeMethods::type_i1`]
-    /// in registers but as [`BaseTypeMethods::type_i8`] in memory.
+    /// `bool` (and other `0`-or-`1` values) are kept as `i1` in registers but as
+    /// [`BaseTypeMethods::type_i8`] in memory.
     ///
     /// Converting values between the two different backend types is done using
     /// [`from_immediate`](super::BuilderMethods::from_immediate) and
diff --git a/compiler/rustc_const_eval/src/const_eval/fn_queries.rs b/compiler/rustc_const_eval/src/const_eval/fn_queries.rs
index 8c66888d100..7acd08e0cce 100644
--- a/compiler/rustc_const_eval/src/const_eval/fn_queries.rs
+++ b/compiler/rustc_const_eval/src/const_eval/fn_queries.rs
@@ -42,10 +42,7 @@ fn constness(tcx: TyCtxt<'_>, def_id: LocalDefId) -> hir::Constness {
         | hir::Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Const(..), .. }) => {
             hir::Constness::Const
         }
-        hir::Node::Item(hir::Item { kind: hir::ItemKind::Impl(_), .. }) => tcx
-            .generics_of(def_id)
-            .host_effect_index
-            .map_or(hir::Constness::NotConst, |_| hir::Constness::Const),
+        hir::Node::Item(hir::Item { kind: hir::ItemKind::Impl(impl_), .. }) => impl_.constness,
         hir::Node::ForeignItem(hir::ForeignItem { kind: hir::ForeignItemKind::Fn(..), .. }) => {
             // Intrinsics use `rustc_const_{un,}stable` attributes to indicate constness. All other
             // foreign items cannot be evaluated at compile-time.
diff --git a/compiler/rustc_const_eval/src/interpret/cast.rs b/compiler/rustc_const_eval/src/interpret/cast.rs
index a13630ce084..83b61ab1749 100644
--- a/compiler/rustc_const_eval/src/interpret/cast.rs
+++ b/compiler/rustc_const_eval/src/interpret/cast.rs
@@ -1,6 +1,6 @@
 use std::assert_matches::assert_matches;
 
-use rustc_apfloat::ieee::{Double, Single};
+use rustc_apfloat::ieee::{Double, Half, Quad, Single};
 use rustc_apfloat::{Float, FloatConvert};
 use rustc_middle::mir::interpret::{InterpResult, PointerArithmetic, Scalar};
 use rustc_middle::mir::CastKind;
@@ -187,10 +187,10 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
             bug!("FloatToFloat/FloatToInt cast: source type {} is not a float type", src.layout.ty)
         };
         let val = match fty {
-            FloatTy::F16 => unimplemented!("f16_f128"),
+            FloatTy::F16 => self.cast_from_float(src.to_scalar().to_f16()?, cast_to.ty),
             FloatTy::F32 => self.cast_from_float(src.to_scalar().to_f32()?, cast_to.ty),
             FloatTy::F64 => self.cast_from_float(src.to_scalar().to_f64()?, cast_to.ty),
-            FloatTy::F128 => unimplemented!("f16_f128"),
+            FloatTy::F128 => self.cast_from_float(src.to_scalar().to_f128()?, cast_to.ty),
         };
         Ok(ImmTy::from_scalar(val, cast_to))
     }
@@ -296,18 +296,18 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
             Float(fty) if signed => {
                 let v = v as i128;
                 match fty {
-                    FloatTy::F16 => unimplemented!("f16_f128"),
+                    FloatTy::F16 => Scalar::from_f16(Half::from_i128(v).value),
                     FloatTy::F32 => Scalar::from_f32(Single::from_i128(v).value),
                     FloatTy::F64 => Scalar::from_f64(Double::from_i128(v).value),
-                    FloatTy::F128 => unimplemented!("f16_f128"),
+                    FloatTy::F128 => Scalar::from_f128(Quad::from_i128(v).value),
                 }
             }
             // unsigned int -> float
             Float(fty) => match fty {
-                FloatTy::F16 => unimplemented!("f16_f128"),
+                FloatTy::F16 => Scalar::from_f16(Half::from_u128(v).value),
                 FloatTy::F32 => Scalar::from_f32(Single::from_u128(v).value),
                 FloatTy::F64 => Scalar::from_f64(Double::from_u128(v).value),
-                FloatTy::F128 => unimplemented!("f16_f128"),
+                FloatTy::F128 => Scalar::from_f128(Quad::from_u128(v).value),
             },
 
             // u8 -> char
@@ -321,7 +321,12 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
     /// Low-level cast helper function. Converts an apfloat `f` into int or float types.
     fn cast_from_float<F>(&self, f: F, dest_ty: Ty<'tcx>) -> Scalar<M::Provenance>
     where
-        F: Float + Into<Scalar<M::Provenance>> + FloatConvert<Single> + FloatConvert<Double>,
+        F: Float
+            + Into<Scalar<M::Provenance>>
+            + FloatConvert<Half>
+            + FloatConvert<Single>
+            + FloatConvert<Double>
+            + FloatConvert<Quad>,
     {
         use rustc_type_ir::TyKind::*;
 
@@ -358,10 +363,12 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
             }
             // float -> float
             Float(fty) => match fty {
-                FloatTy::F16 => unimplemented!("f16_f128"),
+                FloatTy::F16 => Scalar::from_f16(adjust_nan(self, f, f.convert(&mut false).value)),
                 FloatTy::F32 => Scalar::from_f32(adjust_nan(self, f, f.convert(&mut false).value)),
                 FloatTy::F64 => Scalar::from_f64(adjust_nan(self, f, f.convert(&mut false).value)),
-                FloatTy::F128 => unimplemented!("f16_f128"),
+                FloatTy::F128 => {
+                    Scalar::from_f128(adjust_nan(self, f, f.convert(&mut false).value))
+                }
             },
             // That's it.
             _ => span_bug!(self.cur_span(), "invalid float to {} cast", dest_ty),
diff --git a/compiler/rustc_data_structures/Cargo.toml b/compiler/rustc_data_structures/Cargo.toml
index f525510030b..c4b2e067bbe 100644
--- a/compiler/rustc_data_structures/Cargo.toml
+++ b/compiler/rustc_data_structures/Cargo.toml
@@ -50,7 +50,7 @@ libc = "0.2"
 memmap2 = "0.2.1"
 # tidy-alphabetical-end
 
-[target.'cfg(any(target_arch = "mips", target_arch = "powerpc", target_arch = "sparc"))'.dependencies]
+[target.'cfg(not(target_has_atomic = "64"))'.dependencies]
 portable-atomic = "1.5.1"
 
 [features]
diff --git a/compiler/rustc_data_structures/src/marker.rs b/compiler/rustc_data_structures/src/marker.rs
index 32fad0de1aa..83fdaff515b 100644
--- a/compiler/rustc_data_structures/src/marker.rs
+++ b/compiler/rustc_data_structures/src/marker.rs
@@ -147,14 +147,13 @@ cfg_match! {
             [crate::owned_slice::OwnedSlice]
         );
 
-        // MIPS, PowerPC and SPARC platforms with 32-bit pointers do not
-        // have AtomicU64 type.
-        #[cfg(not(any(target_arch = "powerpc", target_arch = "powerpc", target_arch = "sparc")))]
+        // Use portable AtomicU64 for targets without native 64-bit atomics
+        #[cfg(target_has_atomic = "64")]
         already_sync!(
             [std::sync::atomic::AtomicU64]
         );
 
-        #[cfg(any(target_arch = "mips", target_arch = "powerpc", target_arch = "sparc"))]
+        #[cfg(not(target_has_atomic = "64"))]
         already_sync!(
             [portable_atomic::AtomicU64]
         );
diff --git a/compiler/rustc_data_structures/src/sync.rs b/compiler/rustc_data_structures/src/sync.rs
index 5ae79ca988f..79ceb28abb5 100644
--- a/compiler/rustc_data_structures/src/sync.rs
+++ b/compiler/rustc_data_structures/src/sync.rs
@@ -270,12 +270,11 @@ cfg_match! {
 
         pub use std::sync::atomic::{AtomicBool, AtomicUsize, AtomicU32};
 
-        // MIPS, PowerPC and SPARC platforms with 32-bit pointers do not
-        // have AtomicU64 type.
-        #[cfg(not(any(target_arch = "mips", target_arch = "powerpc", target_arch = "sparc")))]
+        // Use portable AtomicU64 for targets without native 64-bit atomics
+        #[cfg(target_has_atomic = "64")]
         pub use std::sync::atomic::AtomicU64;
 
-        #[cfg(any(target_arch = "mips", target_arch = "powerpc", target_arch = "sparc"))]
+        #[cfg(not(target_has_atomic = "64"))]
         pub use portable_atomic::AtomicU64;
 
         pub use std::sync::Arc as Lrc;
diff --git a/compiler/rustc_errors/src/diagnostic.rs b/compiler/rustc_errors/src/diagnostic.rs
index e580910af77..d500f6d88a0 100644
--- a/compiler/rustc_errors/src/diagnostic.rs
+++ b/compiler/rustc_errors/src/diagnostic.rs
@@ -510,7 +510,7 @@ pub struct Diag<'a, G: EmissionGuarantee = ErrorGuaranteed> {
 // would be bad.
 impl<G> !Clone for Diag<'_, G> {}
 
-rustc_data_structures::static_assert_size!(Diag<'_, ()>, 2 * std::mem::size_of::<usize>());
+rustc_data_structures::static_assert_size!(Diag<'_, ()>, 3 * std::mem::size_of::<usize>());
 
 impl<G: EmissionGuarantee> Deref for Diag<'_, G> {
     type Target = DiagInner;
@@ -582,6 +582,11 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
         Self::new_diagnostic(dcx, DiagInner::new(level, message))
     }
 
+    /// Allow moving diagnostics between different error tainting contexts
+    pub fn with_dcx(mut self, dcx: DiagCtxtHandle<'_>) -> Diag<'_, G> {
+        Diag { dcx, diag: self.diag.take(), _marker: PhantomData }
+    }
+
     /// Creates a new `Diag` with an already constructed diagnostic.
     #[track_caller]
     pub(crate) fn new_diagnostic(dcx: DiagCtxtHandle<'a>, diag: DiagInner) -> Self {
diff --git a/compiler/rustc_errors/src/lib.rs b/compiler/rustc_errors/src/lib.rs
index 91112a57277..2086d4030f9 100644
--- a/compiler/rustc_errors/src/lib.rs
+++ b/compiler/rustc_errors/src/lib.rs
@@ -63,6 +63,7 @@ use rustc_span::source_map::SourceMap;
 use rustc_span::{Loc, Span, DUMMY_SP};
 use std::backtrace::{Backtrace, BacktraceStatus};
 use std::borrow::Cow;
+use std::cell::Cell;
 use std::error::Report;
 use std::fmt;
 use std::hash::Hash;
@@ -98,9 +99,9 @@ rustc_fluent_macro::fluent_messages! { "../messages.ftl" }
 
 // `PResult` is used a lot. Make sure it doesn't unintentionally get bigger.
 #[cfg(target_pointer_width = "64")]
-rustc_data_structures::static_assert_size!(PResult<'_, ()>, 16);
+rustc_data_structures::static_assert_size!(PResult<'_, ()>, 24);
 #[cfg(target_pointer_width = "64")]
-rustc_data_structures::static_assert_size!(PResult<'_, bool>, 16);
+rustc_data_structures::static_assert_size!(PResult<'_, bool>, 24);
 
 #[derive(Debug, PartialEq, Eq, Clone, Copy, Hash, Encodable, Decodable)]
 pub enum SuggestionStyle {
@@ -417,6 +418,9 @@ pub struct DiagCtxt {
 #[derive(Copy, Clone)]
 pub struct DiagCtxtHandle<'a> {
     dcx: &'a DiagCtxt,
+    /// Some contexts create `DiagCtxtHandle` with this field set, and thus all
+    /// errors emitted with it will automatically taint when emitting errors.
+    tainted_with_errors: Option<&'a Cell<Option<ErrorGuaranteed>>>,
 }
 
 impl<'a> std::ops::Deref for DiagCtxtHandle<'a> {
@@ -752,7 +756,17 @@ impl DiagCtxt {
     }
 
     pub fn handle<'a>(&'a self) -> DiagCtxtHandle<'a> {
-        DiagCtxtHandle { dcx: self }
+        DiagCtxtHandle { dcx: self, tainted_with_errors: None }
+    }
+
+    /// Link this to a taintable context so that emitting errors will automatically set
+    /// the `Option<ErrorGuaranteed>` instead of having to do that manually at every error
+    /// emission site.
+    pub fn taintable_handle<'a>(
+        &'a self,
+        tainted_with_errors: &'a Cell<Option<ErrorGuaranteed>>,
+    ) -> DiagCtxtHandle<'a> {
+        DiagCtxtHandle { dcx: self, tainted_with_errors: Some(tainted_with_errors) }
     }
 }
 
@@ -795,7 +809,9 @@ impl<'a> DiagCtxtHandle<'a> {
             // can be used to create a backtrace at the stashing site insted of whenever the
             // diagnostic context is dropped and thus delayed bugs are emitted.
             Error => Some(self.span_delayed_bug(span, format!("stashing {key:?}"))),
-            DelayedBug => return self.inner.borrow_mut().emit_diagnostic(diag),
+            DelayedBug => {
+                return self.inner.borrow_mut().emit_diagnostic(diag, self.tainted_with_errors);
+            }
             ForceWarning(_) | Warning | Note | OnceNote | Help | OnceHelp | FailureNote | Allow
             | Expect(_) => None,
         };
@@ -947,16 +963,19 @@ impl<'a> DiagCtxtHandle<'a> {
             (0, _) => {
                 // Use `ForceWarning` rather than `Warning` to guarantee emission, e.g. with a
                 // configuration like `--cap-lints allow --force-warn bare_trait_objects`.
-                inner.emit_diagnostic(DiagInner::new(
-                    ForceWarning(None),
-                    DiagMessage::Str(warnings),
-                ));
+                inner.emit_diagnostic(
+                    DiagInner::new(ForceWarning(None), DiagMessage::Str(warnings)),
+                    None,
+                );
             }
             (_, 0) => {
-                inner.emit_diagnostic(DiagInner::new(Error, errors));
+                inner.emit_diagnostic(DiagInner::new(Error, errors), self.tainted_with_errors);
             }
             (_, _) => {
-                inner.emit_diagnostic(DiagInner::new(Error, format!("{errors}; {warnings}")));
+                inner.emit_diagnostic(
+                    DiagInner::new(Error, format!("{errors}; {warnings}")),
+                    self.tainted_with_errors,
+                );
             }
         }
 
@@ -987,14 +1006,14 @@ impl<'a> DiagCtxtHandle<'a> {
                         "For more information about an error, try `rustc --explain {}`.",
                         &error_codes[0]
                     );
-                    inner.emit_diagnostic(DiagInner::new(FailureNote, msg1));
-                    inner.emit_diagnostic(DiagInner::new(FailureNote, msg2));
+                    inner.emit_diagnostic(DiagInner::new(FailureNote, msg1), None);
+                    inner.emit_diagnostic(DiagInner::new(FailureNote, msg2), None);
                 } else {
                     let msg = format!(
                         "For more information about this error, try `rustc --explain {}`.",
                         &error_codes[0]
                     );
-                    inner.emit_diagnostic(DiagInner::new(FailureNote, msg));
+                    inner.emit_diagnostic(DiagInner::new(FailureNote, msg), None);
                 }
             }
         }
@@ -1020,7 +1039,7 @@ impl<'a> DiagCtxtHandle<'a> {
     }
 
     pub fn emit_diagnostic(&self, diagnostic: DiagInner) -> Option<ErrorGuaranteed> {
-        self.inner.borrow_mut().emit_diagnostic(diagnostic)
+        self.inner.borrow_mut().emit_diagnostic(diagnostic, self.tainted_with_errors)
     }
 
     pub fn emit_artifact_notification(&self, path: &Path, artifact_type: &str) {
@@ -1080,7 +1099,7 @@ impl<'a> DiagCtxtHandle<'a> {
                 // Here the diagnostic is given back to `emit_diagnostic` where it was first
                 // intercepted. Now it should be processed as usual, since the unstable expectation
                 // id is now stable.
-                inner.emit_diagnostic(diag);
+                inner.emit_diagnostic(diag, self.tainted_with_errors);
             }
         }
 
@@ -1430,13 +1449,17 @@ impl DiagCtxtInner {
                     continue;
                 }
             }
-            guar = guar.or(self.emit_diagnostic(diag));
+            guar = guar.or(self.emit_diagnostic(diag, None));
         }
         guar
     }
 
     // Return value is only `Some` if the level is `Error` or `DelayedBug`.
-    fn emit_diagnostic(&mut self, mut diagnostic: DiagInner) -> Option<ErrorGuaranteed> {
+    fn emit_diagnostic(
+        &mut self,
+        mut diagnostic: DiagInner,
+        taint: Option<&Cell<Option<ErrorGuaranteed>>>,
+    ) -> Option<ErrorGuaranteed> {
         match diagnostic.level {
             Expect(expect_id) | ForceWarning(Some(expect_id)) => {
                 // The `LintExpectationId` can be stable or unstable depending on when it was
@@ -1609,6 +1632,9 @@ impl DiagCtxtInner {
                 if is_lint {
                     self.lint_err_guars.push(guar);
                 } else {
+                    if let Some(taint) = taint {
+                        taint.set(Some(guar));
+                    }
                     self.err_guars.push(guar);
                 }
                 self.panic_if_treat_err_as_bug();
@@ -1718,8 +1744,8 @@ impl DiagCtxtInner {
         // `-Ztreat-err-as-bug`, which we don't want.
         let note1 = "no errors encountered even though delayed bugs were created";
         let note2 = "those delayed bugs will now be shown as internal compiler errors";
-        self.emit_diagnostic(DiagInner::new(Note, note1));
-        self.emit_diagnostic(DiagInner::new(Note, note2));
+        self.emit_diagnostic(DiagInner::new(Note, note1), None);
+        self.emit_diagnostic(DiagInner::new(Note, note2), None);
 
         for bug in bugs {
             if let Some(out) = &mut out {
@@ -1752,7 +1778,7 @@ impl DiagCtxtInner {
             }
             bug.level = Bug;
 
-            self.emit_diagnostic(bug);
+            self.emit_diagnostic(bug, None);
         }
 
         // Panic with `DelayedBugPanic` to avoid "unexpected panic" messages.
diff --git a/compiler/rustc_feature/src/builtin_attrs.rs b/compiler/rustc_feature/src/builtin_attrs.rs
index f884f996927..910402d5499 100644
--- a/compiler/rustc_feature/src/builtin_attrs.rs
+++ b/compiler/rustc_feature/src/builtin_attrs.rs
@@ -833,6 +833,10 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
         rustc_const_panic_str, Normal, template!(Word), WarnFollowing,
         EncodeCrossCrate::Yes, INTERNAL_UNSTABLE
     ),
+    rustc_attr!(
+        rustc_runtime, Normal, template!(Word), WarnFollowing,
+        EncodeCrossCrate::No, INTERNAL_UNSTABLE
+    ),
 
     // ==========================================================================
     // Internal attributes, Layout related:
@@ -1114,6 +1118,10 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
         WarnFollowing, EncodeCrossCrate::No
     ),
     rustc_attr!(
+        TEST, rustc_dump_def_parents, Normal, template!(Word),
+        WarnFollowing, EncodeCrossCrate::No
+    ),
+    rustc_attr!(
         TEST, rustc_object_lifetime_default, Normal, template!(Word),
         WarnFollowing, EncodeCrossCrate::No
     ),
diff --git a/compiler/rustc_hir/src/hir.rs b/compiler/rustc_hir/src/hir.rs
index 22a6c06bba3..6cccdec94c0 100644
--- a/compiler/rustc_hir/src/hir.rs
+++ b/compiler/rustc_hir/src/hir.rs
@@ -526,6 +526,7 @@ pub enum GenericParamKind<'hir> {
         /// Optional default value for the const generic param
         default: Option<&'hir AnonConst>,
         is_host_effect: bool,
+        synthetic: bool,
     },
 }
 
@@ -3364,6 +3365,7 @@ pub enum ItemKind<'hir> {
 /// Refer to [`ImplItem`] for an associated item within an impl block.
 #[derive(Debug, Clone, Copy, HashStable_Generic)]
 pub struct Impl<'hir> {
+    pub constness: Constness,
     pub safety: Safety,
     pub polarity: ImplPolarity,
     pub defaultness: Defaultness,
diff --git a/compiler/rustc_hir/src/intravisit.rs b/compiler/rustc_hir/src/intravisit.rs
index 065ecc5d7b7..9bb3245ae05 100644
--- a/compiler/rustc_hir/src/intravisit.rs
+++ b/compiler/rustc_hir/src/intravisit.rs
@@ -543,6 +543,7 @@ pub fn walk_item<'v, V: Visitor<'v>>(visitor: &mut V, item: &'v Item<'v>) -> V::
             try_visit!(visitor.visit_enum_def(enum_definition, item.hir_id()));
         }
         ItemKind::Impl(Impl {
+            constness: _,
             safety: _,
             defaultness: _,
             polarity: _,
@@ -915,7 +916,7 @@ pub fn walk_generic_param<'v, V: Visitor<'v>>(
     match param.kind {
         GenericParamKind::Lifetime { .. } => {}
         GenericParamKind::Type { ref default, .. } => visit_opt!(visitor, visit_ty, default),
-        GenericParamKind::Const { ref ty, ref default, is_host_effect: _ } => {
+        GenericParamKind::Const { ref ty, ref default, is_host_effect: _, synthetic: _ } => {
             try_visit!(visitor.visit_ty(ty));
             if let Some(ref default) = default {
                 try_visit!(visitor.visit_const_param_default(param.hir_id, default));
diff --git a/compiler/rustc_hir/src/lang_items.rs b/compiler/rustc_hir/src/lang_items.rs
index 69461957f80..3c44acb1657 100644
--- a/compiler/rustc_hir/src/lang_items.rs
+++ b/compiler/rustc_hir/src/lang_items.rs
@@ -393,6 +393,14 @@ language_item_table! {
 
     String,                  sym::String,              string,                     Target::Struct,         GenericRequirement::None;
     CStr,                    sym::CStr,                c_str,                      Target::Struct,         GenericRequirement::None;
+
+    EffectsRuntime,          sym::EffectsRuntime,      effects_runtime,            Target::Struct,         GenericRequirement::None;
+    EffectsNoRuntime,        sym::EffectsNoRuntime,    effects_no_runtime,         Target::Struct,         GenericRequirement::None;
+    EffectsMaybe,            sym::EffectsMaybe,        effects_maybe,              Target::Struct,         GenericRequirement::None;
+    EffectsIntersection,     sym::EffectsIntersection, effects_intersection,       Target::Trait,          GenericRequirement::None;
+    EffectsIntersectionOutput, sym::EffectsIntersectionOutput, effects_intersection_output, Target::AssocTy, GenericRequirement::None;
+    EffectsCompat,           sym::EffectsCompat,       effects_compat,             Target::Trait,          GenericRequirement::Exact(1);
+    EffectsTyCompat,         sym::EffectsTyCompat,     effects_ty_compat,          Target::Trait,          GenericRequirement::Exact(1);
 }
 
 pub enum GenericRequirement {
diff --git a/compiler/rustc_hir_analysis/messages.ftl b/compiler/rustc_hir_analysis/messages.ftl
index 7ed32fb9d9f..064d9c077b0 100644
--- a/compiler/rustc_hir_analysis/messages.ftl
+++ b/compiler/rustc_hir_analysis/messages.ftl
@@ -120,6 +120,10 @@ hir_analysis_drop_impl_reservation = reservation `Drop` impls are not supported
 hir_analysis_duplicate_precise_capture = cannot capture parameter `{$name}` twice
     .label = parameter captured again here
 
+hir_analysis_effects_without_next_solver = using `#![feature(effects)]` without enabling next trait solver globally
+    .note = the next trait solver must be enabled globally for the effects feature to work correctly
+    .help = use `-Znext-solver` to enable
+
 hir_analysis_empty_specialization = specialization impl does not specialize any associated items
     .note = impl is a specialization of this impl
 
diff --git a/compiler/rustc_hir_analysis/src/bounds.rs b/compiler/rustc_hir_analysis/src/bounds.rs
index 7f0d72b3a8d..c7ee89e73c2 100644
--- a/compiler/rustc_hir_analysis/src/bounds.rs
+++ b/compiler/rustc_hir_analysis/src/bounds.rs
@@ -1,9 +1,13 @@
 //! Bounds are restrictions applied to some types after they've been lowered from the HIR to the
 //! [`rustc_middle::ty`] form.
 
+use rustc_data_structures::fx::FxIndexMap;
+use rustc_hir::def::DefKind;
 use rustc_hir::LangItem;
+use rustc_middle::ty::fold::FnMutDelegate;
 use rustc_middle::ty::{self, Ty, TyCtxt, Upcast};
-use rustc_span::Span;
+use rustc_span::def_id::DefId;
+use rustc_span::{sym, Span};
 
 /// Collects together a list of type bounds. These lists of bounds occur in many places
 /// in Rust's syntax:
@@ -24,6 +28,7 @@ use rustc_span::Span;
 #[derive(Default, PartialEq, Eq, Clone, Debug)]
 pub struct Bounds<'tcx> {
     clauses: Vec<(ty::Clause<'tcx>, Span)>,
+    effects_min_tys: FxIndexMap<Ty<'tcx>, Span>,
 }
 
 impl<'tcx> Bounds<'tcx> {
@@ -40,12 +45,14 @@ impl<'tcx> Bounds<'tcx> {
     pub fn push_trait_bound(
         &mut self,
         tcx: TyCtxt<'tcx>,
-        trait_ref: ty::PolyTraitRef<'tcx>,
+        defining_def_id: DefId,
+        bound_trait_ref: ty::PolyTraitRef<'tcx>,
         span: Span,
         polarity: ty::PredicatePolarity,
+        constness: ty::BoundConstness,
     ) {
         let clause = (
-            trait_ref
+            bound_trait_ref
                 .map_bound(|trait_ref| {
                     ty::ClauseKind::Trait(ty::TraitPredicate { trait_ref, polarity })
                 })
@@ -53,11 +60,98 @@ impl<'tcx> Bounds<'tcx> {
             span,
         );
         // FIXME(-Znext-solver): We can likely remove this hack once the new trait solver lands.
-        if tcx.is_lang_item(trait_ref.def_id(), LangItem::Sized) {
+        if tcx.is_lang_item(bound_trait_ref.def_id(), LangItem::Sized) {
             self.clauses.insert(0, clause);
         } else {
             self.clauses.push(clause);
         }
+
+        if !tcx.features().effects {
+            return;
+        }
+        // For `T: ~const Tr` or `T: const Tr`, we need to add an additional bound on the
+        // associated type of `<T as Tr>` and make sure that the effect is compatible.
+        let compat_val = match (tcx.def_kind(defining_def_id), constness) {
+            // FIXME(effects): revisit the correctness of this
+            (_, ty::BoundConstness::Const) => tcx.consts.false_,
+            // body owners that can have trait bounds
+            (DefKind::Const | DefKind::Fn | DefKind::AssocFn, ty::BoundConstness::ConstIfConst) => {
+                tcx.expected_host_effect_param_for_body(defining_def_id)
+            }
+
+            (_, ty::BoundConstness::NotConst) => {
+                if !tcx.has_attr(bound_trait_ref.def_id(), sym::const_trait) {
+                    return;
+                }
+                tcx.consts.true_
+            }
+
+            (
+                DefKind::Trait | DefKind::Impl { of_trait: true },
+                ty::BoundConstness::ConstIfConst,
+            ) => {
+                // this is either a where clause on an impl/trait header or on a trait.
+                // push `<T as Tr>::Effects` into the set for the `Min` bound.
+                let Some(assoc) = tcx.associated_type_for_effects(bound_trait_ref.def_id()) else {
+                    tcx.dcx().span_delayed_bug(span, "`~const` on trait without Effects assoc");
+                    return;
+                };
+
+                let ty = bound_trait_ref
+                    .map_bound(|trait_ref| Ty::new_projection(tcx, assoc, trait_ref.args));
+
+                // When the user has written `for<'a, T> X<'a, T>: ~const Foo`, replace the
+                // binders to dummy ones i.e. `X<'static, ()>` so they can be referenced in
+                // the `Min` associated type properly (which doesn't allow using `for<>`)
+                // This should work for any bound variables as long as they don't have any
+                // bounds e.g. `for<T: Trait>`.
+                // FIXME(effects) reconsider this approach to allow compatibility with `for<T: Tr>`
+                let ty = tcx.replace_bound_vars_uncached(
+                    ty,
+                    FnMutDelegate {
+                        regions: &mut |_| tcx.lifetimes.re_static,
+                        types: &mut |_| tcx.types.unit,
+                        consts: &mut |_| unimplemented!("`~const` does not support const binders"),
+                    },
+                );
+
+                self.effects_min_tys.insert(ty, span);
+                return;
+            }
+            // for
+            // ```
+            // trait Foo { type Bar: ~const Trait }
+            // ```
+            // ensure that `<Self::Bar as Trait>::Effects: TyCompat<Self::Effects>`.
+            //
+            // FIXME(effects) this is equality for now, which wouldn't be helpful for a non-const implementor
+            // that uses a `Bar` that implements `Trait` with `Maybe` effects.
+            (DefKind::AssocTy, ty::BoundConstness::ConstIfConst) => {
+                // FIXME(effects): implement this
+                return;
+            }
+            // probably illegal in this position.
+            (_, ty::BoundConstness::ConstIfConst) => {
+                tcx.dcx().span_delayed_bug(span, "invalid `~const` encountered");
+                return;
+            }
+        };
+        // create a new projection type `<T as Tr>::Effects`
+        let Some(assoc) = tcx.associated_type_for_effects(bound_trait_ref.def_id()) else {
+            tcx.dcx().span_delayed_bug(
+                span,
+                "`~const` trait bound has no effect assoc yet no errors encountered?",
+            );
+            return;
+        };
+        let self_ty = Ty::new_projection(tcx, assoc, bound_trait_ref.skip_binder().args);
+        // make `<T as Tr>::Effects: Compat<runtime>`
+        let new_trait_ref = ty::TraitRef::new(
+            tcx,
+            tcx.require_lang_item(LangItem::EffectsCompat, Some(span)),
+            [ty::GenericArg::from(self_ty), compat_val.into()],
+        );
+        self.clauses.push((bound_trait_ref.rebind(new_trait_ref).upcast(tcx), span));
     }
 
     pub fn push_projection_bound(
@@ -79,7 +173,15 @@ impl<'tcx> Bounds<'tcx> {
         self.clauses.insert(0, (trait_ref.upcast(tcx), span));
     }
 
-    pub fn clauses(&self) -> impl Iterator<Item = (ty::Clause<'tcx>, Span)> + '_ {
+    pub fn clauses(
+        &self,
+        // FIXME(effects): remove tcx
+        _tcx: TyCtxt<'tcx>,
+    ) -> impl Iterator<Item = (ty::Clause<'tcx>, Span)> + '_ {
         self.clauses.iter().cloned()
     }
+
+    pub fn effects_min_tys(&self) -> impl Iterator<Item = Ty<'tcx>> + '_ {
+        self.effects_min_tys.keys().copied()
+    }
 }
diff --git a/compiler/rustc_hir_analysis/src/check/check.rs b/compiler/rustc_hir_analysis/src/check/check.rs
index e13ea1a1935..f93777eda52 100644
--- a/compiler/rustc_hir_analysis/src/check/check.rs
+++ b/compiler/rustc_hir_analysis/src/check/check.rs
@@ -879,7 +879,8 @@ pub(super) fn check_specialization_validity<'tcx>(
     let result = opt_result.unwrap_or(Ok(()));
 
     if let Err(parent_impl) = result {
-        if !tcx.is_impl_trait_in_trait(impl_item) {
+        // FIXME(effects) the associated type from effects could be specialized
+        if !tcx.is_impl_trait_in_trait(impl_item) && !tcx.is_effects_desugared_assoc_ty(impl_item) {
             report_forbidden_specialization(tcx, impl_item, parent_impl);
         } else {
             tcx.dcx().delayed_bug(format!("parent item: {parent_impl:?} not marked as default"));
diff --git a/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs b/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
index 7fa5c96bc9a..b5b68471b9d 100644
--- a/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
+++ b/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
@@ -1985,10 +1985,10 @@ pub(super) fn check_type_bounds<'tcx>(
     let infcx = tcx.infer_ctxt().build();
     let ocx = ObligationCtxt::new_with_diagnostics(&infcx);
 
-    // A synthetic impl Trait for RPITIT desugaring has no HIR, which we currently use to get the
-    // span for an impl's associated type. Instead, for these, use the def_span for the synthesized
-    // associated type.
-    let impl_ty_span = if impl_ty.is_impl_trait_in_trait() {
+    // A synthetic impl Trait for RPITIT desugaring or assoc type for effects desugaring has no HIR,
+    // which we currently use to get the span for an impl's associated type. Instead, for these,
+    // use the def_span for the synthesized  associated type.
+    let impl_ty_span = if impl_ty.is_impl_trait_in_trait() || impl_ty.is_effects_desugaring {
         tcx.def_span(impl_ty_def_id)
     } else {
         match tcx.hir_node_by_def_id(impl_ty_def_id) {
diff --git a/compiler/rustc_hir_analysis/src/check/wfcheck.rs b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
index a188c1b12ae..2230528a5ae 100644
--- a/compiler/rustc_hir_analysis/src/check/wfcheck.rs
+++ b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
@@ -913,7 +913,12 @@ fn check_param_wf(tcx: TyCtxt<'_>, param: &hir::GenericParam<'_>) -> Result<(),
         hir::GenericParamKind::Lifetime { .. } | hir::GenericParamKind::Type { .. } => Ok(()),
 
         // Const parameters are well formed if their type is structural match.
-        hir::GenericParamKind::Const { ty: hir_ty, default: _, is_host_effect: _ } => {
+        hir::GenericParamKind::Const {
+            ty: hir_ty,
+            default: _,
+            is_host_effect: _,
+            synthetic: _,
+        } => {
             let ty = tcx.type_of(param.def_id).instantiate_identity();
 
             if tcx.features().adt_const_params {
diff --git a/compiler/rustc_hir_analysis/src/collect.rs b/compiler/rustc_hir_analysis/src/collect.rs
index e7892f17660..41fbef48940 100644
--- a/compiler/rustc_hir_analysis/src/collect.rs
+++ b/compiler/rustc_hir_analysis/src/collect.rs
@@ -70,10 +70,10 @@ pub fn provide(providers: &mut Providers) {
         predicates_of: predicates_of::predicates_of,
         predicates_defined_on,
         explicit_predicates_of: predicates_of::explicit_predicates_of,
-        super_predicates_of: predicates_of::super_predicates_of,
-        implied_predicates_of: predicates_of::implied_predicates_of,
-        super_predicates_that_define_assoc_item:
-            predicates_of::super_predicates_that_define_assoc_item,
+        explicit_super_predicates_of: predicates_of::explicit_super_predicates_of,
+        explicit_implied_predicates_of: predicates_of::explicit_implied_predicates_of,
+        explicit_supertraits_containing_assoc_item:
+            predicates_of::explicit_supertraits_containing_assoc_item,
         trait_explicit_predicates_and_bounds: predicates_of::trait_explicit_predicates_and_bounds,
         type_param_predicates: predicates_of::type_param_predicates,
         trait_def,
@@ -691,14 +691,14 @@ fn lower_item(tcx: TyCtxt<'_>, item_id: hir::ItemId) {
         hir::ItemKind::Trait(..) => {
             tcx.ensure().generics_of(def_id);
             tcx.ensure().trait_def(def_id);
-            tcx.at(it.span).super_predicates_of(def_id);
+            tcx.at(it.span).explicit_super_predicates_of(def_id);
             tcx.ensure().predicates_of(def_id);
             tcx.ensure().associated_items(def_id);
         }
         hir::ItemKind::TraitAlias(..) => {
             tcx.ensure().generics_of(def_id);
-            tcx.at(it.span).implied_predicates_of(def_id);
-            tcx.at(it.span).super_predicates_of(def_id);
+            tcx.at(it.span).explicit_implied_predicates_of(def_id);
+            tcx.at(it.span).explicit_super_predicates_of(def_id);
             tcx.ensure().predicates_of(def_id);
         }
         hir::ItemKind::Struct(struct_def, _) | hir::ItemKind::Union(struct_def, _) => {
@@ -1459,8 +1459,25 @@ fn infer_return_ty_for_fn_sig<'tcx>(
         Some(ty) => {
             let fn_sig = tcx.typeck(def_id).liberated_fn_sigs()[hir_id];
             // Typeck doesn't expect erased regions to be returned from `type_of`.
+            // This is a heuristic approach. If the scope has region paramters,
+            // we should change fn_sig's lifetime from `ReErased` to `ReError`,
+            // otherwise to `ReStatic`.
+            let has_region_params = generics.params.iter().any(|param| match param.kind {
+                GenericParamKind::Lifetime { .. } => true,
+                _ => false,
+            });
             let fn_sig = tcx.fold_regions(fn_sig, |r, _| match *r {
-                ty::ReErased => tcx.lifetimes.re_static,
+                ty::ReErased => {
+                    if has_region_params {
+                        ty::Region::new_error_with_message(
+                            tcx,
+                            DUMMY_SP,
+                            "erased region is not allowed here in return type",
+                        )
+                    } else {
+                        tcx.lifetimes.re_static
+                    }
+                }
                 _ => r,
             });
 
@@ -1638,44 +1655,19 @@ fn impl_trait_header(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Option<ty::ImplTrai
     let icx = ItemCtxt::new(tcx, def_id);
     let item = tcx.hir().expect_item(def_id);
     let impl_ = item.expect_impl();
-    impl_
-        .of_trait
-        .as_ref()
-        .map(|hir_trait_ref| {
-            let self_ty = tcx.type_of(def_id).instantiate_identity();
+    impl_.of_trait.as_ref().map(|ast_trait_ref| {
+        let selfty = tcx.type_of(def_id).instantiate_identity();
 
-            let trait_ref = if let Some(ErrorGuaranteed { .. }) = check_impl_constness(
-                tcx,
-                tcx.is_const_trait_impl_raw(def_id.to_def_id()),
-                hir_trait_ref,
-            ) {
-                // we have a const impl, but for a trait without `#[const_trait]`, so
-                // without the host param. If we continue with the HIR trait ref, we get
-                // ICEs for generic arg count mismatch. We do a little HIR editing to
-                // make HIR ty lowering happy.
-                let mut path_segments = hir_trait_ref.path.segments.to_vec();
-                let last_segment = path_segments.len() - 1;
-                let mut args = *path_segments[last_segment].args();
-                let last_arg = args.args.len() - 1;
-                assert!(matches!(args.args[last_arg], hir::GenericArg::Const(anon_const) if anon_const.is_desugared_from_effects));
-                args.args = &args.args[..args.args.len() - 1];
-                path_segments[last_segment].args = Some(tcx.hir_arena.alloc(args));
-                let path = hir::Path {
-                    span: hir_trait_ref.path.span,
-                    res: hir_trait_ref.path.res,
-                    segments: tcx.hir_arena.alloc_slice(&path_segments),
-                };
-                let trait_ref = tcx.hir_arena.alloc(hir::TraitRef { path: tcx.hir_arena.alloc(path), hir_ref_id: hir_trait_ref.hir_ref_id });
-                icx.lowerer().lower_impl_trait_ref(trait_ref, self_ty)
-            } else {
-                icx.lowerer().lower_impl_trait_ref(hir_trait_ref, self_ty)
-            };
-            ty::ImplTraitHeader {
-                trait_ref: ty::EarlyBinder::bind(trait_ref),
-                safety: impl_.safety,
-                polarity: polarity_of_impl(tcx, def_id, impl_, item.span)
-            }
-        })
+        check_impl_constness(tcx, tcx.is_const_trait_impl_raw(def_id.to_def_id()), ast_trait_ref);
+
+        let trait_ref = icx.lowerer().lower_impl_trait_ref(ast_trait_ref, selfty);
+
+        ty::ImplTraitHeader {
+            trait_ref: ty::EarlyBinder::bind(trait_ref),
+            safety: impl_.safety,
+            polarity: polarity_of_impl(tcx, def_id, impl_, item.span),
+        }
+    })
 }
 
 fn check_impl_constness(
diff --git a/compiler/rustc_hir_analysis/src/collect/dump.rs b/compiler/rustc_hir_analysis/src/collect/dump.rs
index 85e1c600d6d..c73d3a5390d 100644
--- a/compiler/rustc_hir_analysis/src/collect/dump.rs
+++ b/compiler/rustc_hir_analysis/src/collect/dump.rs
@@ -1,5 +1,7 @@
 use rustc_hir::def::DefKind;
-use rustc_hir::def_id::CRATE_DEF_ID;
+use rustc_hir::def_id::{LocalDefId, CRATE_DEF_ID};
+use rustc_hir::intravisit;
+use rustc_middle::hir::nested_filter::OnlyBodies;
 use rustc_middle::ty::TyCtxt;
 use rustc_span::sym;
 
@@ -41,3 +43,49 @@ pub(crate) fn predicates_and_item_bounds(tcx: TyCtxt<'_>) {
         }
     }
 }
+
+pub(crate) fn def_parents(tcx: TyCtxt<'_>) {
+    for did in tcx.hir().body_owners() {
+        if tcx.has_attr(did, sym::rustc_dump_def_parents) {
+            struct AnonConstFinder<'tcx> {
+                tcx: TyCtxt<'tcx>,
+                anon_consts: Vec<LocalDefId>,
+            }
+
+            impl<'tcx> intravisit::Visitor<'tcx> for AnonConstFinder<'tcx> {
+                type NestedFilter = OnlyBodies;
+
+                fn nested_visit_map(&mut self) -> Self::Map {
+                    self.tcx.hir()
+                }
+
+                fn visit_anon_const(&mut self, c: &'tcx rustc_hir::AnonConst) {
+                    self.anon_consts.push(c.def_id);
+                    intravisit::walk_anon_const(self, c)
+                }
+            }
+
+            // Look for any anon consts inside of this body owner as there is no way to apply
+            // the `rustc_dump_def_parents` attribute to the anon const so it would not be possible
+            // to see what its def parent is.
+            let mut anon_ct_finder = AnonConstFinder { tcx, anon_consts: vec![] };
+            intravisit::walk_expr(&mut anon_ct_finder, tcx.hir().body_owned_by(did).value);
+
+            for did in [did].into_iter().chain(anon_ct_finder.anon_consts) {
+                let span = tcx.def_span(did);
+
+                let mut diag = tcx.dcx().struct_span_err(
+                    span,
+                    format!("{}: {did:?}", sym::rustc_dump_def_parents.as_str()),
+                );
+
+                let mut current_did = did.to_def_id();
+                while let Some(parent_did) = tcx.opt_parent(current_did) {
+                    current_did = parent_did;
+                    diag.span_note(tcx.def_span(parent_did), format!("{parent_did:?}"));
+                }
+                diag.emit();
+            }
+        }
+    }
+}
diff --git a/compiler/rustc_hir_analysis/src/collect/generics_of.rs b/compiler/rustc_hir_analysis/src/collect/generics_of.rs
index 303fa23dbc1..9b02c1a61fa 100644
--- a/compiler/rustc_hir_analysis/src/collect/generics_of.rs
+++ b/compiler/rustc_hir_analysis/src/collect/generics_of.rs
@@ -354,7 +354,7 @@ pub(super) fn generics_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Generics {
                 kind,
             })
         }
-        GenericParamKind::Const { ty: _, default, is_host_effect } => {
+        GenericParamKind::Const { ty: _, default, is_host_effect, synthetic } => {
             if !matches!(allow_defaults, Defaults::Allowed)
                 && default.is_some()
                 // `host` effect params are allowed to have defaults.
@@ -388,6 +388,7 @@ pub(super) fn generics_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Generics {
                 kind: ty::GenericParamDefKind::Const {
                     has_default: default.is_some(),
                     is_host_effect,
+                    synthetic,
                 },
             })
         }
@@ -541,7 +542,8 @@ struct AnonConstInParamTyDetector {
 
 impl<'v> Visitor<'v> for AnonConstInParamTyDetector {
     fn visit_generic_param(&mut self, p: &'v hir::GenericParam<'v>) {
-        if let GenericParamKind::Const { ty, default: _, is_host_effect: _ } = p.kind {
+        if let GenericParamKind::Const { ty, default: _, is_host_effect: _, synthetic: _ } = p.kind
+        {
             let prev = self.in_param_ty;
             self.in_param_ty = true;
             self.visit_ty(ty);
diff --git a/compiler/rustc_hir_analysis/src/collect/item_bounds.rs b/compiler/rustc_hir_analysis/src/collect/item_bounds.rs
index d084d3aefeb..c03e074c80b 100644
--- a/compiler/rustc_hir_analysis/src/collect/item_bounds.rs
+++ b/compiler/rustc_hir_analysis/src/collect/item_bounds.rs
@@ -8,6 +8,7 @@ use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable, TypeFolder, TypeSuperFold
 use rustc_middle::{bug, span_bug};
 use rustc_span::def_id::{DefId, LocalDefId};
 use rustc_span::Span;
+use rustc_type_ir::Upcast;
 
 /// For associated types we include both bounds written on the type
 /// (`type X: Trait`) and predicates from the trait: `where Self::X: Trait`.
@@ -46,7 +47,7 @@ fn associated_type_bounds<'tcx>(
         }
     });
 
-    let all_bounds = tcx.arena.alloc_from_iter(bounds.clauses().chain(bounds_from_parent));
+    let all_bounds = tcx.arena.alloc_from_iter(bounds.clauses(tcx).chain(bounds_from_parent));
     debug!(
         "associated_type_bounds({}) = {:?}",
         tcx.def_path_str(assoc_item_def_id.to_def_id()),
@@ -75,7 +76,7 @@ fn opaque_type_bounds<'tcx>(
         icx.lowerer().add_sized_bound(&mut bounds, item_ty, hir_bounds, None, span);
         debug!(?bounds);
 
-        tcx.arena.alloc_from_iter(bounds.clauses())
+        tcx.arena.alloc_from_iter(bounds.clauses(tcx))
     })
 }
 
@@ -124,6 +125,32 @@ pub(super) fn explicit_item_bounds_with_filter(
         None => {}
     }
 
+    if tcx.is_effects_desugared_assoc_ty(def_id.to_def_id()) {
+        let mut predicates = Vec::new();
+
+        let parent = tcx.local_parent(def_id);
+
+        let preds = tcx.explicit_predicates_of(parent);
+
+        if let ty::AssocItemContainer::TraitContainer = tcx.associated_item(def_id).container {
+            // for traits, emit `type Effects: TyCompat<<(T1::Effects, ..) as Min>::Output>`
+            let tup = Ty::new(tcx, ty::Tuple(preds.effects_min_tys));
+            // FIXME(effects) span
+            let span = tcx.def_span(def_id);
+            let assoc = tcx.require_lang_item(hir::LangItem::EffectsIntersectionOutput, Some(span));
+            let proj = Ty::new_projection(tcx, assoc, [tup]);
+            let self_proj = Ty::new_projection(
+                tcx,
+                def_id.to_def_id(),
+                ty::GenericArgs::identity_for_item(tcx, def_id),
+            );
+            let trait_ = tcx.require_lang_item(hir::LangItem::EffectsTyCompat, Some(span));
+            let trait_ref = ty::TraitRef::new(tcx, trait_, [self_proj, proj]);
+            predicates.push((ty::Binder::dummy(trait_ref).upcast(tcx), span));
+        }
+        return ty::EarlyBinder::bind(tcx.arena.alloc_from_iter(predicates));
+    }
+
     let bounds = match tcx.hir_node_by_def_id(def_id) {
         hir::Node::TraitItem(hir::TraitItem {
             kind: hir::TraitItemKind::Type(bounds, _),
diff --git a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
index 3421c8da4e9..b89d034fc2e 100644
--- a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
+++ b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
@@ -57,6 +57,7 @@ pub(super) fn predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredic
 #[instrument(level = "trace", skip(tcx), ret)]
 fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::GenericPredicates<'_> {
     use rustc_hir::*;
+    use rustc_middle::ty::Ty;
 
     match tcx.opt_rpitit_info(def_id.to_def_id()) {
         Some(ImplTraitInTraitData::Trait { fn_def_id, .. }) => {
@@ -84,6 +85,7 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Gen
             return ty::GenericPredicates {
                 parent: Some(tcx.parent(def_id.to_def_id())),
                 predicates: tcx.arena.alloc_from_iter(predicates),
+                effects_min_tys: ty::List::empty(),
             };
         }
 
@@ -105,6 +107,7 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Gen
             return ty::GenericPredicates {
                 parent: Some(impl_def_id),
                 predicates: tcx.arena.alloc_from_iter(impl_predicates),
+                effects_min_tys: ty::List::empty(),
             };
         }
 
@@ -124,6 +127,7 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Gen
     // We use an `IndexSet` to preserve order of insertion.
     // Preserving the order of insertion is important here so as not to break UI tests.
     let mut predicates: FxIndexSet<(ty::Clause<'_>, Span)> = FxIndexSet::default();
+    let mut effects_min_tys = Vec::new();
 
     let hir_generics = node.generics().unwrap_or(NO_GENERICS);
     if let Node::Item(item) = node {
@@ -150,11 +154,13 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Gen
     // on a trait we must also consider the bounds that follow the trait's name,
     // like `trait Foo: A + B + C`.
     if let Some(self_bounds) = is_trait {
-        predicates.extend(
-            icx.lowerer()
-                .lower_mono_bounds(tcx.types.self_param, self_bounds, PredicateFilter::All)
-                .clauses(),
+        let bounds = icx.lowerer().lower_mono_bounds(
+            tcx.types.self_param,
+            self_bounds,
+            PredicateFilter::All,
         );
+        predicates.extend(bounds.clauses(tcx));
+        effects_min_tys.extend(bounds.effects_min_tys());
     }
 
     // In default impls, we can assume that the self type implements
@@ -187,7 +193,7 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Gen
                     param.span,
                 );
                 trace!(?bounds);
-                predicates.extend(bounds.clauses());
+                predicates.extend(bounds.clauses(tcx));
                 trace!(?predicates);
             }
             hir::GenericParamKind::Const { .. } => {
@@ -238,7 +244,8 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Gen
                     bound_vars,
                     OnlySelfBounds(false),
                 );
-                predicates.extend(bounds.clauses());
+                predicates.extend(bounds.clauses(tcx));
+                effects_min_tys.extend(bounds.effects_min_tys());
             }
 
             hir::WherePredicate::RegionPredicate(region_pred) => {
@@ -297,7 +304,8 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Gen
     // and the duplicated parameter, to ensure that they do not get out of sync.
     if let Node::Item(&Item { kind: ItemKind::OpaqueTy(..), .. }) = node {
         let opaque_ty_node = tcx.parent_hir_node(hir_id);
-        let Node::Ty(&Ty { kind: TyKind::OpaqueDef(_, lifetimes, _), .. }) = opaque_ty_node else {
+        let Node::Ty(&hir::Ty { kind: TyKind::OpaqueDef(_, lifetimes, _), .. }) = opaque_ty_node
+        else {
             bug!("unexpected {opaque_ty_node:?}")
         };
         debug!(?lifetimes);
@@ -306,9 +314,30 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Gen
         debug!(?predicates);
     }
 
+    // add `Self::Effects: Compat<HOST>` to ensure non-const impls don't get called
+    // in const contexts.
+    if let Node::TraitItem(&TraitItem { kind: TraitItemKind::Fn(..), .. }) = node
+        && let Some(host_effect_index) = generics.host_effect_index
+    {
+        let parent = generics.parent.unwrap();
+        let Some(assoc_def_id) = tcx.associated_type_for_effects(parent) else {
+            bug!("associated_type_for_effects returned None when there is host effect in generics");
+        };
+        let effects =
+            Ty::new_projection(tcx, assoc_def_id, ty::GenericArgs::identity_for_item(tcx, parent));
+        let param = generics.param_at(host_effect_index, tcx);
+        let span = tcx.def_span(param.def_id);
+        let host = ty::Const::new_param(tcx, ty::ParamConst::for_def(param));
+        let compat = tcx.require_lang_item(LangItem::EffectsCompat, Some(span));
+        let trait_ref =
+            ty::TraitRef::new(tcx, compat, [ty::GenericArg::from(effects), host.into()]);
+        predicates.push((ty::Binder::dummy(trait_ref).upcast(tcx), span));
+    }
+
     ty::GenericPredicates {
         parent: generics.parent,
         predicates: tcx.arena.alloc_from_iter(predicates),
+        effects_min_tys: tcx.mk_type_list(&effects_min_tys),
     }
 }
 
@@ -459,6 +488,7 @@ pub(super) fn explicit_predicates_of<'tcx>(
             ty::GenericPredicates {
                 parent: predicates_and_bounds.parent,
                 predicates: tcx.arena.alloc_slice(&predicates),
+                effects_min_tys: predicates_and_bounds.effects_min_tys,
             }
         }
     } else {
@@ -510,6 +540,7 @@ pub(super) fn explicit_predicates_of<'tcx>(
             return GenericPredicates {
                 parent: parent_preds.parent,
                 predicates: { tcx.arena.alloc_from_iter(filtered_predicates) },
+                effects_min_tys: parent_preds.effects_min_tys,
             };
         }
         gather_explicit_predicates_of(tcx, def_id)
@@ -519,21 +550,21 @@ pub(super) fn explicit_predicates_of<'tcx>(
 /// Ensures that the super-predicates of the trait with a `DefId`
 /// of `trait_def_id` are lowered and stored. This also ensures that
 /// the transitive super-predicates are lowered.
-pub(super) fn super_predicates_of(
+pub(super) fn explicit_super_predicates_of(
     tcx: TyCtxt<'_>,
     trait_def_id: LocalDefId,
 ) -> ty::GenericPredicates<'_> {
     implied_predicates_with_filter(tcx, trait_def_id.to_def_id(), PredicateFilter::SelfOnly)
 }
 
-pub(super) fn super_predicates_that_define_assoc_item(
+pub(super) fn explicit_supertraits_containing_assoc_item(
     tcx: TyCtxt<'_>,
     (trait_def_id, assoc_name): (DefId, Ident),
 ) -> ty::GenericPredicates<'_> {
     implied_predicates_with_filter(tcx, trait_def_id, PredicateFilter::SelfThatDefines(assoc_name))
 }
 
-pub(super) fn implied_predicates_of(
+pub(super) fn explicit_implied_predicates_of(
     tcx: TyCtxt<'_>,
     trait_def_id: LocalDefId,
 ) -> ty::GenericPredicates<'_> {
@@ -560,7 +591,7 @@ pub(super) fn implied_predicates_with_filter(
         // if `assoc_name` is None, then the query should've been redirected to an
         // external provider
         assert!(matches!(filter, PredicateFilter::SelfThatDefines(_)));
-        return tcx.super_predicates_of(trait_def_id);
+        return tcx.explicit_super_predicates_of(trait_def_id);
     };
 
     let Node::Item(item) = tcx.hir_node_by_def_id(trait_def_id) else {
@@ -587,7 +618,7 @@ pub(super) fn implied_predicates_with_filter(
 
     // Combine the two lists to form the complete set of superbounds:
     let implied_bounds =
-        &*tcx.arena.alloc_from_iter(superbounds.clauses().chain(where_bounds_that_match));
+        &*tcx.arena.alloc_from_iter(superbounds.clauses(tcx).chain(where_bounds_that_match));
     debug!(?implied_bounds);
 
     // Now require that immediate supertraits are lowered, which will, in
@@ -601,7 +632,7 @@ pub(super) fn implied_predicates_with_filter(
                 if let ty::ClauseKind::Trait(bound) = pred.kind().skip_binder()
                     && bound.polarity == ty::PredicatePolarity::Positive
                 {
-                    tcx.at(span).super_predicates_of(bound.def_id());
+                    tcx.at(span).explicit_super_predicates_of(bound.def_id());
                 }
             }
         }
@@ -611,14 +642,18 @@ pub(super) fn implied_predicates_with_filter(
                 if let ty::ClauseKind::Trait(bound) = pred.kind().skip_binder()
                     && bound.polarity == ty::PredicatePolarity::Positive
                 {
-                    tcx.at(span).implied_predicates_of(bound.def_id());
+                    tcx.at(span).explicit_implied_predicates_of(bound.def_id());
                 }
             }
         }
         _ => {}
     }
 
-    ty::GenericPredicates { parent: None, predicates: implied_bounds }
+    ty::GenericPredicates {
+        parent: None,
+        predicates: implied_bounds,
+        effects_min_tys: ty::List::empty(),
+    }
 }
 
 /// Returns the predicates defined on `item_def_id` of the form
@@ -744,7 +779,7 @@ impl<'tcx> ItemCtxt<'tcx> {
             );
         }
 
-        bounds.clauses().collect()
+        bounds.clauses(self.tcx).collect()
     }
 
     #[instrument(level = "trace", skip(self))]
diff --git a/compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs b/compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs
index abc3bb838db..cad7870a0a1 100644
--- a/compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs
+++ b/compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs
@@ -951,7 +951,7 @@ impl<'a, 'tcx> Visitor<'tcx> for BoundVarContext<'a, 'tcx> {
                     self.visit_ty(ty);
                 }
             }
-            GenericParamKind::Const { ty, default, is_host_effect: _ } => {
+            GenericParamKind::Const { ty, default, .. } => {
                 self.visit_ty(ty);
                 if let Some(default) = default {
                     self.visit_body(self.tcx.hir().body(default.body));
@@ -1760,7 +1760,7 @@ impl<'a, 'tcx> BoundVarContext<'a, 'tcx> {
             if let Some(assoc_item) = trait_defines_associated_item_named(def_id) {
                 break Some((bound_vars.into_iter().collect(), assoc_item));
             }
-            let predicates = tcx.super_predicates_that_define_assoc_item((def_id, assoc_name));
+            let predicates = tcx.explicit_supertraits_containing_assoc_item((def_id, assoc_name));
             let obligations = predicates.predicates.iter().filter_map(|&(pred, _)| {
                 let bound_predicate = pred.kind();
                 match bound_predicate.skip_binder() {
diff --git a/compiler/rustc_hir_analysis/src/errors.rs b/compiler/rustc_hir_analysis/src/errors.rs
index 44025c3cd61..3ffb51fa992 100644
--- a/compiler/rustc_hir_analysis/src/errors.rs
+++ b/compiler/rustc_hir_analysis/src/errors.rs
@@ -1699,3 +1699,9 @@ pub struct InvalidReceiverTy<'tcx> {
     pub span: Span,
     pub receiver_ty: Ty<'tcx>,
 }
+
+#[derive(Diagnostic)]
+#[diag(hir_analysis_effects_without_next_solver)]
+#[note]
+#[help]
+pub struct EffectsWithoutNextSolver;
diff --git a/compiler/rustc_hir_analysis/src/hir_ty_lowering/generics.rs b/compiler/rustc_hir_analysis/src/hir_ty_lowering/generics.rs
index 3f888c4e272..e92c377f0ce 100644
--- a/compiler/rustc_hir_analysis/src/hir_ty_lowering/generics.rs
+++ b/compiler/rustc_hir_analysis/src/hir_ty_lowering/generics.rs
@@ -256,6 +256,7 @@ pub fn lower_generic_args<'tcx: 'a, 'a>(
                             | GenericParamDefKind::Lifetime,
                             _,
                         ) => {
+                            // FIXME(effects): this should be removed
                             // SPECIAL CASE FOR DESUGARED EFFECT PARAMS
                             // This comes from the following example:
                             //
@@ -445,7 +446,7 @@ pub(crate) fn check_generic_arg_count(
         .own_params
         .iter()
         .filter(|param| {
-            matches!(param.kind, ty::GenericParamDefKind::Const { is_host_effect: true, .. })
+            matches!(param.kind, ty::GenericParamDefKind::Const { synthetic: true, .. })
         })
         .count();
     let named_const_param_count = param_counts.consts - synth_const_param_count;
diff --git a/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs b/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs
index 24ea328889c..2a68d3915bb 100644
--- a/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs
+++ b/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs
@@ -698,7 +698,14 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         );
 
         debug!(?poly_trait_ref);
-        bounds.push_trait_bound(tcx, poly_trait_ref, span, polarity);
+        bounds.push_trait_bound(
+            tcx,
+            self.item_def_id().to_def_id(),
+            poly_trait_ref,
+            span,
+            polarity,
+            constness,
+        );
 
         let mut dup_constraints = FxIndexMap::default();
         for constraint in trait_segment.args().constraints {
diff --git a/compiler/rustc_hir_analysis/src/hir_ty_lowering/object_safety.rs b/compiler/rustc_hir_analysis/src/hir_ty_lowering/object_safety.rs
index 34924f09d09..df69c1938dd 100644
--- a/compiler/rustc_hir_analysis/src/hir_ty_lowering/object_safety.rs
+++ b/compiler/rustc_hir_analysis/src/hir_ty_lowering/object_safety.rs
@@ -59,7 +59,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
 
         let mut trait_bounds = vec![];
         let mut projection_bounds = vec![];
-        for (pred, span) in bounds.clauses() {
+        for (pred, span) in bounds.clauses(tcx) {
             let bound_pred = pred.kind();
             match bound_pred.skip_binder() {
                 ty::ClauseKind::Trait(trait_pred) => {
@@ -133,7 +133,9 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                             tcx.associated_items(pred.def_id())
                                 .in_definition_order()
                                 .filter(|item| item.kind == ty::AssocKind::Type)
-                                .filter(|item| !item.is_impl_trait_in_trait())
+                                .filter(|item| {
+                                    !item.is_impl_trait_in_trait() && !item.is_effects_desugaring
+                                })
                                 .map(|item| item.def_id),
                         );
                     }
diff --git a/compiler/rustc_hir_analysis/src/lib.rs b/compiler/rustc_hir_analysis/src/lib.rs
index 0428abcdf24..44f1830a3b1 100644
--- a/compiler/rustc_hir_analysis/src/lib.rs
+++ b/compiler/rustc_hir_analysis/src/lib.rs
@@ -151,6 +151,12 @@ pub fn provide(providers: &mut Providers) {
 pub fn check_crate(tcx: TyCtxt<'_>) {
     let _prof_timer = tcx.sess.timer("type_check_crate");
 
+    // FIXME(effects): remove once effects is implemented in old trait solver
+    // or if the next solver is stabilized.
+    if tcx.features().effects && !tcx.next_trait_solver_globally() {
+        tcx.dcx().emit_err(errors::EffectsWithoutNextSolver);
+    }
+
     tcx.sess.time("coherence_checking", || {
         tcx.hir().par_for_each_module(|module| {
             let _ = tcx.ensure().check_mod_type_wf(module);
@@ -169,6 +175,7 @@ pub fn check_crate(tcx: TyCtxt<'_>) {
         tcx.sess.time("variance_dumping", || variance::dump::variances(tcx));
         collect::dump::opaque_hidden_types(tcx);
         collect::dump::predicates_and_item_bounds(tcx);
+        collect::dump::def_parents(tcx);
     }
 
     // Make sure we evaluate all static and (non-associated) const items, even if unused.
diff --git a/compiler/rustc_hir_pretty/src/lib.rs b/compiler/rustc_hir_pretty/src/lib.rs
index 25b0cbdc026..5105d60ae18 100644
--- a/compiler/rustc_hir_pretty/src/lib.rs
+++ b/compiler/rustc_hir_pretty/src/lib.rs
@@ -585,6 +585,7 @@ impl<'a> State<'a> {
                 self.print_struct(struct_def, generics, item.ident.name, item.span, true);
             }
             hir::ItemKind::Impl(&hir::Impl {
+                constness,
                 safety,
                 polarity,
                 defaultness,
@@ -599,6 +600,10 @@ impl<'a> State<'a> {
                 self.print_safety(safety);
                 self.word_nbsp("impl");
 
+                if let hir::Constness::Const = constness {
+                    self.word_nbsp("const");
+                }
+
                 if !generics.params.is_empty() {
                     self.print_generic_params(generics.params);
                     self.space();
@@ -2144,7 +2149,7 @@ impl<'a> State<'a> {
                     self.print_type(default);
                 }
             }
-            GenericParamKind::Const { ty, ref default, is_host_effect: _ } => {
+            GenericParamKind::Const { ty, ref default, is_host_effect: _, synthetic: _ } => {
                 self.word_space(":");
                 self.print_type(ty);
                 if let Some(default) = default {
diff --git a/compiler/rustc_hir_typeck/src/cast.rs b/compiler/rustc_hir_typeck/src/cast.rs
index 92f2d3254bb..cb1a412d17e 100644
--- a/compiler/rustc_hir_typeck/src/cast.rs
+++ b/compiler/rustc_hir_typeck/src/cast.rs
@@ -319,7 +319,7 @@ impl<'a, 'tcx> CastCheck<'tcx> {
                 } else {
                     errors::CannotCastToBoolHelp::Unsupported(self.span)
                 };
-                fcx.tcx.dcx().emit_err(errors::CannotCastToBool { span: self.span, expr_ty, help });
+                fcx.dcx().emit_err(errors::CannotCastToBool { span: self.span, expr_ty, help });
             }
             CastError::CastToChar => {
                 let mut err = type_error_struct!(
diff --git a/compiler/rustc_hir_typeck/src/coercion.rs b/compiler/rustc_hir_typeck/src/coercion.rs
index 0551b9bc1f0..f72e8a4afde 100644
--- a/compiler/rustc_hir_typeck/src/coercion.rs
+++ b/compiler/rustc_hir_typeck/src/coercion.rs
@@ -1797,16 +1797,16 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> {
         err.subdiagnostic(SuggestBoxingForReturnImplTrait::BoxReturnExpr { starts, ends });
     }
 
-    fn report_return_mismatched_types<'a>(
+    fn report_return_mismatched_types<'infcx>(
         &self,
         cause: &ObligationCause<'tcx>,
         expected: Ty<'tcx>,
         found: Ty<'tcx>,
         ty_err: TypeError<'tcx>,
-        fcx: &FnCtxt<'a, 'tcx>,
+        fcx: &'infcx FnCtxt<'_, 'tcx>,
         block_or_return_id: hir::HirId,
         expression: Option<&'tcx hir::Expr<'tcx>>,
-    ) -> Diag<'a> {
+    ) -> Diag<'infcx> {
         let mut err = fcx.err_ctxt().report_mismatched_types(cause, expected, found, ty_err);
 
         let due_to_block = matches!(fcx.tcx.hir_node(block_or_return_id), hir::Node::Block(..));
diff --git a/compiler/rustc_hir_typeck/src/demand.rs b/compiler/rustc_hir_typeck/src/demand.rs
index f9720c9c307..ad9c1e28211 100644
--- a/compiler/rustc_hir_typeck/src/demand.rs
+++ b/compiler/rustc_hir_typeck/src/demand.rs
@@ -172,21 +172,21 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     }
 
     pub fn demand_suptype_diag(
-        &self,
+        &'a self,
         sp: Span,
         expected: Ty<'tcx>,
         actual: Ty<'tcx>,
-    ) -> Result<(), Diag<'tcx>> {
+    ) -> Result<(), Diag<'a>> {
         self.demand_suptype_with_origin(&self.misc(sp), expected, actual)
     }
 
     #[instrument(skip(self), level = "debug")]
     pub fn demand_suptype_with_origin(
-        &self,
+        &'a self,
         cause: &ObligationCause<'tcx>,
         expected: Ty<'tcx>,
         actual: Ty<'tcx>,
-    ) -> Result<(), Diag<'tcx>> {
+    ) -> Result<(), Diag<'a>> {
         self.at(cause, self.param_env)
             .sup(DefineOpaqueTypes::Yes, expected, actual)
             .map(|infer_ok| self.register_infer_ok_obligations(infer_ok))
@@ -200,20 +200,20 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     }
 
     pub fn demand_eqtype_diag(
-        &self,
+        &'a self,
         sp: Span,
         expected: Ty<'tcx>,
         actual: Ty<'tcx>,
-    ) -> Result<(), Diag<'tcx>> {
+    ) -> Result<(), Diag<'a>> {
         self.demand_eqtype_with_origin(&self.misc(sp), expected, actual)
     }
 
     pub fn demand_eqtype_with_origin(
-        &self,
+        &'a self,
         cause: &ObligationCause<'tcx>,
         expected: Ty<'tcx>,
         actual: Ty<'tcx>,
-    ) -> Result<(), Diag<'tcx>> {
+    ) -> Result<(), Diag<'a>> {
         self.at(cause, self.param_env)
             .eq(DefineOpaqueTypes::Yes, expected, actual)
             .map(|infer_ok| self.register_infer_ok_obligations(infer_ok))
@@ -247,13 +247,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     /// will be permitted if the diverges flag is currently "always".
     #[instrument(level = "debug", skip(self, expr, expected_ty_expr, allow_two_phase))]
     pub fn demand_coerce_diag(
-        &self,
+        &'a self,
         mut expr: &'tcx hir::Expr<'tcx>,
         checked_ty: Ty<'tcx>,
         expected: Ty<'tcx>,
         mut expected_ty_expr: Option<&'tcx hir::Expr<'tcx>>,
         allow_two_phase: AllowTwoPhase,
-    ) -> Result<Ty<'tcx>, Diag<'tcx>> {
+    ) -> Result<Ty<'tcx>, Diag<'a>> {
         let expected = self.resolve_vars_with_obligations(expected);
 
         let e = match self.coerce(expr, checked_ty, expected, allow_two_phase, None) {
diff --git a/compiler/rustc_hir_typeck/src/expr.rs b/compiler/rustc_hir_typeck/src/expr.rs
index f4e1e461953..2fbc8a3f146 100644
--- a/compiler/rustc_hir_typeck/src/expr.rs
+++ b/compiler/rustc_hir_typeck/src/expr.rs
@@ -638,7 +638,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 // Set expectation to error in that case and set tainted
                 // by error (#114529)
                 let coerce_to = opt_coerce_to.unwrap_or_else(|| {
-                    let guar = tcx.dcx().span_delayed_bug(
+                    let guar = self.dcx().span_delayed_bug(
                         expr.span,
                         "illegal break with value found but no error reported",
                     );
@@ -1716,7 +1716,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             } else {
                 error_happened = true;
                 let guar = if let Some(prev_span) = seen_fields.get(&ident) {
-                    tcx.dcx().emit_err(FieldMultiplySpecifiedInInitializer {
+                    self.dcx().emit_err(FieldMultiplySpecifiedInInitializer {
                         span: field.ident.span,
                         prev_span: *prev_span,
                         ident,
@@ -1757,7 +1757,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         if adt_kind == AdtKind::Union {
             if hir_fields.len() != 1 {
                 struct_span_code_err!(
-                    tcx.dcx(),
+                    self.dcx(),
                     span,
                     E0784,
                     "union expressions should have exactly one field",
diff --git a/compiler/rustc_hir_typeck/src/expr_use_visitor.rs b/compiler/rustc_hir_typeck/src/expr_use_visitor.rs
index 0ba4bd090f5..9a353bfe49d 100644
--- a/compiler/rustc_hir_typeck/src/expr_use_visitor.rs
+++ b/compiler/rustc_hir_typeck/src/expr_use_visitor.rs
@@ -170,7 +170,7 @@ impl<'tcx> TypeInformationCtxt<'tcx> for &FnCtxt<'_, 'tcx> {
     }
 
     fn report_error(&self, span: Span, msg: impl ToString) -> Self::Error {
-        self.tcx.dcx().span_delayed_bug(span, msg.to_string())
+        self.dcx().span_delayed_bug(span, msg.to_string())
     }
 
     fn error_reported_in_ty(&self, ty: Ty<'tcx>) -> Result<(), Self::Error> {
diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs
index 061afd03062..5450243417f 100644
--- a/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs
+++ b/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs
@@ -1182,7 +1182,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     name: self.tcx.item_name(def.did()).to_ident_string(),
                 });
                 if ty.raw.has_param() {
-                    let guar = self.tcx.dcx().emit_err(errors::SelfCtorFromOuterItem {
+                    let guar = self.dcx().emit_err(errors::SelfCtorFromOuterItem {
                         span: path_span,
                         impl_span: tcx.def_span(impl_def_id),
                         sugg,
@@ -1207,7 +1207,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     // Check the visibility of the ctor.
                     let vis = tcx.visibility(ctor_def_id);
                     if !vis.is_accessible_from(tcx.parent_module(hir_id).to_def_id(), tcx) {
-                        tcx.dcx()
+                        self.dcx()
                             .emit_err(CtorIsPrivate { span, def: tcx.def_path_str(adt_def.did()) });
                     }
                     let new_res = Res::Def(DefKind::Ctor(CtorOf::Struct, ctor_kind), ctor_def_id);
@@ -1216,7 +1216,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     (new_res, Some(user_args.args))
                 }
                 _ => {
-                    let mut err = tcx.dcx().struct_span_err(
+                    let mut err = self.dcx().struct_span_err(
                         span,
                         "the `Self` constructor can only be used with tuple or unit structs",
                     );
@@ -1304,7 +1304,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         self.fcx.ty_infer(Some(param), inf.span).into()
                     }
                     (
-                        &GenericParamDefKind::Const { has_default, is_host_effect },
+                        &GenericParamDefKind::Const { has_default, is_host_effect, .. },
                         GenericArg::Infer(inf),
                     ) => {
                         if has_default && is_host_effect {
@@ -1346,7 +1346,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                             self.fcx.var_for_def(self.span, param)
                         }
                     }
-                    GenericParamDefKind::Const { has_default, is_host_effect } => {
+                    GenericParamDefKind::Const { has_default, is_host_effect, .. } => {
                         if has_default {
                             // N.B. this is a bit of a hack. `infer_args` is passed depending on
                             // whether the user has provided generic args. E.g. for `Vec::new`
diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs
index 1138642c56d..c6d72700b3f 100644
--- a/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs
+++ b/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs
@@ -238,7 +238,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     // Otherwise, there's a mismatch, so clear out what we're expecting, and set
                     // our input types to err_args so we don't blow up the error messages
                     let guar = struct_span_code_err!(
-                        tcx.dcx(),
+                        self.dcx(),
                         call_span,
                         E0059,
                         "cannot use call notation; the first type parameter \
@@ -453,7 +453,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     .map(|vars| self.resolve_vars_if_possible(vars)),
             );
 
-            self.set_tainted_by_errors(self.report_arg_errors(
+            self.report_arg_errors(
                 compatibility_diagonal,
                 formal_and_expected_inputs,
                 provided_args,
@@ -462,7 +462,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 fn_def_id,
                 call_span,
                 call_expr,
-            ));
+            );
         }
     }
 
@@ -788,7 +788,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                             format!("arguments to this {call_name} are incorrect"),
                         );
                     } else {
-                        err = tcx.dcx().struct_span_err(
+                        err = self.dcx().struct_span_err(
                             full_call_span,
                             format!(
                                 "{call_name} takes {}{} but {} {} supplied",
@@ -848,7 +848,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 span_bug!(error_span, "expected errors from argument matrix");
             } else {
                 let mut err =
-                    tcx.dcx().create_err(errors::ArgMismatchIndeterminate { span: error_span });
+                    self.dcx().create_err(errors::ArgMismatchIndeterminate { span: error_span });
                 suggest_confusable(&mut err);
                 return err.emit();
             }
@@ -951,16 +951,42 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             return err.emit();
         }
 
+        // Special case, we found an extra argument is provided, which is very common in practice.
+        // but there is a obviously better removing suggestion compared to the current one,
+        // try to find the argument with Error type, if we removed it all the types will become good,
+        // then we will replace the current suggestion.
+        if let [Error::Extra(provided_idx)] = &errors[..] {
+            let remove_idx_is_perfect = |idx: usize| -> bool {
+                let removed_arg_tys = provided_arg_tys
+                    .iter()
+                    .enumerate()
+                    .filter_map(|(j, arg)| if idx == j { None } else { Some(arg) })
+                    .collect::<IndexVec<ProvidedIdx, _>>();
+                std::iter::zip(formal_and_expected_inputs.iter(), removed_arg_tys.iter()).all(
+                    |((expected_ty, _), (provided_ty, _))| {
+                        !provided_ty.references_error()
+                            && self.can_coerce(*provided_ty, *expected_ty)
+                    },
+                )
+            };
+
+            if !remove_idx_is_perfect(provided_idx.as_usize()) {
+                if let Some(i) = (0..provided_args.len()).find(|&i| remove_idx_is_perfect(i)) {
+                    errors = vec![Error::Extra(ProvidedIdx::from_usize(i))];
+                }
+            }
+        }
+
         let mut err = if formal_and_expected_inputs.len() == provided_args.len() {
             struct_span_code_err!(
-                tcx.dcx(),
+                self.dcx(),
                 full_call_span,
                 E0308,
                 "arguments to this {} are incorrect",
                 call_name,
             )
         } else {
-            tcx.dcx()
+            self.dcx()
                 .struct_span_err(
                     full_call_span,
                     format!(
@@ -1424,7 +1450,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         expected_ty: Ty<'tcx>,
         provided_ty: Ty<'tcx>,
         arg: &hir::Expr<'tcx>,
-        err: &mut Diag<'tcx>,
+        err: &mut Diag<'_>,
     ) {
         if let ty::RawPtr(_, hir::Mutability::Mut) = expected_ty.kind()
             && let ty::RawPtr(_, hir::Mutability::Not) = provided_ty.kind()
@@ -2042,7 +2068,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     }
                     if block_num > 1 && found_semi {
                         err.span_suggestion_verbose(
-                            span.shrink_to_lo(),
+                            // use the span of the *whole* expr
+                            self.tcx.hir().span(binding_hir_id).shrink_to_lo(),
                             "you might have meant to return this to infer its type parameters",
                             "return ",
                             Applicability::MaybeIncorrect,
diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs
index c0d60477967..da68da029b4 100644
--- a/compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs
+++ b/compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs
@@ -144,8 +144,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         }
     }
 
-    pub(crate) fn dcx(&self) -> DiagCtxtHandle<'tcx> {
-        self.infcx.dcx()
+    pub(crate) fn dcx(&self) -> DiagCtxtHandle<'a> {
+        self.root_ctxt.infcx.dcx()
     }
 
     pub fn cause(&self, span: Span, code: ObligationCauseCode<'tcx>) -> ObligationCause<'tcx> {
@@ -274,6 +274,7 @@ impl<'tcx> HirTyLowerer<'tcx> for FnCtxt<'_, 'tcx> {
                     }
                 }),
             ),
+            effects_min_tys: ty::List::empty(),
         }
     }
 
diff --git a/compiler/rustc_hir_typeck/src/intrinsicck.rs b/compiler/rustc_hir_typeck/src/intrinsicck.rs
index 5eafc60a04e..0389c06c312 100644
--- a/compiler/rustc_hir_typeck/src/intrinsicck.rs
+++ b/compiler/rustc_hir_typeck/src/intrinsicck.rs
@@ -52,7 +52,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             // Note: this path is currently not reached in any test, so any
             // example that triggers this would be worth minimizing and
             // converting into a test.
-            tcx.dcx().span_bug(span, "argument to transmute has inference variables");
+            self.dcx().span_bug(span, "argument to transmute has inference variables");
         }
         // Transmutes that are only changing lifetimes are always ok.
         if from == to {
@@ -76,7 +76,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             if let (&ty::FnDef(..), SizeSkeleton::Known(size_to, _)) = (from.kind(), sk_to)
                 && size_to == Pointer(dl.instruction_address_space).size(&tcx)
             {
-                struct_span_code_err!(tcx.dcx(), span, E0591, "can't transmute zero-sized type")
+                struct_span_code_err!(self.dcx(), span, E0591, "can't transmute zero-sized type")
                     .with_note(format!("source type: {from}"))
                     .with_note(format!("target type: {to}"))
                     .with_help("cast with `as` to a pointer instead")
@@ -116,7 +116,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         };
 
         let mut err = struct_span_code_err!(
-            tcx.dcx(),
+            self.dcx(),
             span,
             E0512,
             "cannot transmute between types of different sizes, \
diff --git a/compiler/rustc_hir_typeck/src/method/mod.rs b/compiler/rustc_hir_typeck/src/method/mod.rs
index e1223307b53..ff8899ae036 100644
--- a/compiler/rustc_hir_typeck/src/method/mod.rs
+++ b/compiler/rustc_hir_typeck/src/method/mod.rs
@@ -21,7 +21,7 @@ use rustc_middle::ty::{self, GenericParamDefKind, Ty, TypeVisitableExt};
 use rustc_middle::ty::{GenericArgs, GenericArgsRef};
 use rustc_middle::{bug, span_bug};
 use rustc_span::symbol::Ident;
-use rustc_span::Span;
+use rustc_span::{sym, Span};
 use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt;
 use rustc_trait_selection::traits::{self, NormalizeExt};
 
@@ -356,6 +356,17 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     ) -> Option<InferOk<'tcx, MethodCallee<'tcx>>> {
         let (obligation, args) =
             self.obligation_for_method(cause, trait_def_id, self_ty, opt_input_types);
+        // FIXME(effects) find a better way to do this
+        // Operators don't have generic methods, but making them `#[const_trait]` gives them
+        // `const host: bool`.
+        let args = if self.tcx.has_attr(trait_def_id, sym::const_trait) {
+            self.tcx.mk_args_from_iter(
+                args.iter()
+                    .chain([self.tcx.expected_host_effect_param_for_body(self.body_id).into()]),
+            )
+        } else {
+            args
+        };
         self.construct_obligation_for_trait(m_name, trait_def_id, obligation, args)
     }
 
@@ -393,6 +404,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         debug!("lookup_in_trait_adjusted: method_item={:?}", method_item);
         let mut obligations = vec![];
 
+        // FIXME(effects): revisit when binops get `#[const_trait]`
+
         // Instantiate late-bound regions and instantiate the trait
         // parameters into the method type to get the actual method type.
         //
diff --git a/compiler/rustc_hir_typeck/src/method/probe.rs b/compiler/rustc_hir_typeck/src/method/probe.rs
index 9747a91ccbf..63b30d79aba 100644
--- a/compiler/rustc_hir_typeck/src/method/probe.rs
+++ b/compiler/rustc_hir_typeck/src/method/probe.rs
@@ -1279,6 +1279,7 @@ impl<'tcx> Pick<'tcx> {
                     trait_item_def_id: _,
                     fn_has_self_parameter: _,
                     opt_rpitit_info: _,
+                    is_effects_desugaring: _,
                 },
             kind: _,
             import_ids: _,
diff --git a/compiler/rustc_hir_typeck/src/method/suggest.rs b/compiler/rustc_hir_typeck/src/method/suggest.rs
index a385bc70e35..e310730bf9e 100644
--- a/compiler/rustc_hir_typeck/src/method/suggest.rs
+++ b/compiler/rustc_hir_typeck/src/method/suggest.rs
@@ -705,7 +705,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         let mut err = if is_write && let SelfSource::MethodCall(rcvr_expr) = source {
             self.suggest_missing_writer(rcvr_ty, rcvr_expr)
         } else {
-            let mut err = tcx.dcx().create_err(NoAssociatedItem {
+            let mut err = self.dcx().create_err(NoAssociatedItem {
                 span,
                 item_kind,
                 item_name,
@@ -1194,7 +1194,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         span: item_span,
                         ..
                     })) => {
-                        tcx.dcx().span_delayed_bug(
+                        self.dcx().span_delayed_bug(
                             *item_span,
                             "auto trait is invoked with no method error, but no error reported?",
                         );
@@ -2361,7 +2361,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     );
                     if pick.is_ok() {
                         let range_span = parent_expr.span.with_hi(expr.span.hi());
-                        return Err(tcx.dcx().emit_err(errors::MissingParenthesesInRange {
+                        return Err(self.dcx().emit_err(errors::MissingParenthesesInRange {
                             span,
                             ty_str: ty_str.to_string(),
                             method_name: item_name.as_str().to_string(),
@@ -2420,7 +2420,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             && let SelfSource::MethodCall(expr) = source
         {
             let mut err = struct_span_code_err!(
-                tcx.dcx(),
+                self.dcx(),
                 span,
                 E0689,
                 "can't call {} `{}` on ambiguous numeric type `{}`",
diff --git a/compiler/rustc_hir_typeck/src/pat.rs b/compiler/rustc_hir_typeck/src/pat.rs
index aaf3d3ec34d..f932a27e9a2 100644
--- a/compiler/rustc_hir_typeck/src/pat.rs
+++ b/compiler/rustc_hir_typeck/src/pat.rs
@@ -89,7 +89,7 @@ struct PatInfo<'tcx, 'a> {
     current_depth: u32,
 }
 
-impl<'tcx> FnCtxt<'_, 'tcx> {
+impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     fn pattern_cause(&self, ti: &TopInfo<'tcx>, cause_span: Span) -> ObligationCause<'tcx> {
         let code = ObligationCauseCode::Pattern {
             span: ti.span,
@@ -100,12 +100,12 @@ impl<'tcx> FnCtxt<'_, 'tcx> {
     }
 
     fn demand_eqtype_pat_diag(
-        &self,
+        &'a self,
         cause_span: Span,
         expected: Ty<'tcx>,
         actual: Ty<'tcx>,
         ti: &TopInfo<'tcx>,
-    ) -> Result<(), Diag<'tcx>> {
+    ) -> Result<(), Diag<'a>> {
         self.demand_eqtype_with_origin(&self.pattern_cause(ti, cause_span), expected, actual)
             .map_err(|mut diag| {
                 if let Some(expr) = ti.origin_expr {
@@ -698,7 +698,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             && let MutblCap::WeaklyNot(and_pat_span) = pat_info.max_ref_mutbl
         {
             let mut err = struct_span_code_err!(
-                self.tcx.dcx(),
+                self.dcx(),
                 ident.span,
                 E0596,
                 "cannot borrow as mutable inside an `&` pattern"
@@ -1010,7 +1010,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         let (res, opt_ty, segments) = path_resolution;
         match res {
             Res::Err => {
-                let e = tcx.dcx().span_delayed_bug(qpath.span(), "`Res::Err` but no error emitted");
+                let e =
+                    self.dcx().span_delayed_bug(qpath.span(), "`Res::Err` but no error emitted");
                 self.set_tainted_by_errors(e);
                 return Ty::new_error(tcx, e);
             }
@@ -1191,7 +1192,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         let (res, opt_ty, segments) =
             self.resolve_ty_and_res_fully_qualified_call(qpath, pat.hir_id, pat.span);
         if res == Res::Err {
-            let e = tcx.dcx().span_delayed_bug(pat.span, "`Res::Err` but no error emitted");
+            let e = self.dcx().span_delayed_bug(pat.span, "`Res::Err` but no error emitted");
             self.set_tainted_by_errors(e);
             on_error(e);
             return Ty::new_error(tcx, e);
@@ -1207,7 +1208,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
         let variant = match res {
             Res::Err => {
-                tcx.dcx().span_bug(pat.span, "`Res::Err` but no error emitted");
+                self.dcx().span_bug(pat.span, "`Res::Err` but no error emitted");
             }
             Res::Def(DefKind::AssocConst | DefKind::AssocFn, _) => {
                 let e = report_unexpected_res(res);
@@ -1549,10 +1550,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         // Report an error if an incorrect number of fields was specified.
         if adt.is_union() {
             if fields.len() != 1 {
-                tcx.dcx().emit_err(errors::UnionPatMultipleFields { span: pat.span });
+                self.dcx().emit_err(errors::UnionPatMultipleFields { span: pat.span });
             }
             if has_rest_pat {
-                tcx.dcx().emit_err(errors::UnionPatDotDot { span: pat.span });
+                self.dcx().emit_err(errors::UnionPatDotDot { span: pat.span });
             }
         } else if !unmentioned_fields.is_empty() {
             let accessible_unmentioned_fields: Vec<_> = unmentioned_fields
@@ -1690,7 +1691,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         pat: &'tcx Pat<'tcx>,
         variant: &ty::VariantDef,
         args: ty::GenericArgsRef<'tcx>,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'a> {
         let tcx = self.tcx;
         let (field_names, t, plural) = if let [field] = inexistent_fields {
             (format!("a field named `{}`", field.ident), "this", "")
@@ -1710,7 +1711,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         };
         let spans = inexistent_fields.iter().map(|field| field.ident.span).collect::<Vec<_>>();
         let mut err = struct_span_code_err!(
-            tcx.dcx(),
+            self.dcx(),
             spans,
             E0026,
             "{} `{}` does not have {}",
@@ -1881,7 +1882,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         &self,
         pat: &Pat<'_>,
         fields: &'tcx [hir::PatField<'tcx>],
-    ) -> Diag<'tcx> {
+    ) -> Diag<'a> {
         let mut err = self
             .dcx()
             .struct_span_err(pat.span, "pattern requires `..` due to inaccessible fields");
@@ -1973,7 +1974,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         unmentioned_fields: &[(&ty::FieldDef, Ident)],
         have_inaccessible_fields: bool,
         fields: &'tcx [hir::PatField<'tcx>],
-    ) -> Diag<'tcx> {
+    ) -> Diag<'a> {
         let inaccessible = if have_inaccessible_fields { " and inaccessible fields" } else { "" };
         let field_names = if let [(_, field)] = unmentioned_fields {
             format!("field `{field}`{inaccessible}")
diff --git a/compiler/rustc_infer/src/infer/error_reporting/mod.rs b/compiler/rustc_infer/src/infer/error_reporting/mod.rs
index 227691d0994..a8fd3ca8c59 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/mod.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/mod.rs
@@ -139,7 +139,7 @@ pub struct TypeErrCtxt<'a, 'tcx> {
 }
 
 impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
-    pub fn dcx(&self) -> DiagCtxtHandle<'tcx> {
+    pub fn dcx(&self) -> DiagCtxtHandle<'a> {
         self.infcx.dcx()
     }
 
@@ -305,16 +305,17 @@ fn label_msg_span(
     }
 }
 
-#[instrument(level = "trace", skip(tcx))]
-pub fn unexpected_hidden_region_diagnostic<'tcx>(
-    tcx: TyCtxt<'tcx>,
+#[instrument(level = "trace", skip(infcx))]
+pub fn unexpected_hidden_region_diagnostic<'a, 'tcx>(
+    infcx: &'a InferCtxt<'tcx>,
     generic_param_scope: LocalDefId,
     span: Span,
     hidden_ty: Ty<'tcx>,
     hidden_region: ty::Region<'tcx>,
     opaque_ty_key: ty::OpaqueTypeKey<'tcx>,
-) -> Diag<'tcx> {
-    let mut err = tcx.dcx().create_err(errors::OpaqueCapturesLifetime {
+) -> Diag<'a> {
+    let tcx = infcx.tcx;
+    let mut err = infcx.dcx().create_err(errors::OpaqueCapturesLifetime {
         span,
         opaque_ty: Ty::new_opaque(tcx, opaque_ty_key.def_id.to_def_id(), opaque_ty_key.args),
         opaque_ty_span: tcx.def_span(opaque_ty_key.def_id),
@@ -436,7 +437,7 @@ impl<'tcx> InferCtxt<'tcx> {
     }
 }
 
-impl<'tcx> TypeErrCtxt<'_, 'tcx> {
+impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
     pub fn report_region_errors(
         &self,
         generic_param_scope: LocalDefId,
@@ -2206,7 +2207,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         &self,
         trace: TypeTrace<'tcx>,
         terr: TypeError<'tcx>,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'a> {
         debug!("report_and_explain_type_error(trace={:?}, terr={:?})", trace, terr);
 
         let span = trace.cause.span();
@@ -2215,7 +2216,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
             span,
             self.type_error_additional_suggestions(&trace, terr),
         );
-        let mut diag = self.tcx.dcx().create_err(failure_code);
+        let mut diag = self.dcx().create_err(failure_code);
         self.note_type_err(&mut diag, &trace.cause, None, Some(trace.values), terr, false, false);
         diag
     }
@@ -2357,14 +2358,14 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         origin: Option<SubregionOrigin<'tcx>>,
         bound_kind: GenericKind<'tcx>,
         sub: Region<'tcx>,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'a> {
         if let Some(SubregionOrigin::CompareImplItemObligation {
             span,
             impl_item_def_id,
             trait_item_def_id,
         }) = origin
         {
-            return self.report_extra_impl_obligation(
+            return self.infcx.report_extra_impl_obligation(
                 span,
                 impl_item_def_id,
                 trait_item_def_id,
@@ -2790,7 +2791,7 @@ impl<'tcx> TypeRelation<TyCtxt<'tcx>> for SameTypeModuloInfer<'_, 'tcx> {
 }
 
 impl<'tcx> InferCtxt<'tcx> {
-    fn report_inference_failure(&self, var_origin: RegionVariableOrigin) -> Diag<'tcx> {
+    fn report_inference_failure(&self, var_origin: RegionVariableOrigin) -> Diag<'_> {
         let br_string = |br: ty::BoundRegionKind| {
             let mut s = match br {
                 ty::BrNamed(_, name) => name.to_string(),
@@ -2829,7 +2830,7 @@ impl<'tcx> InferCtxt<'tcx> {
         };
 
         struct_span_code_err!(
-            self.tcx.dcx(),
+            self.dcx(),
             var_origin.span(),
             E0495,
             "cannot infer an appropriate lifetime{} due to conflicting requirements",
diff --git a/compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs b/compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs
index d7349abc44c..084aebc296f 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs
@@ -391,7 +391,7 @@ impl<'tcx> InferCtxt<'tcx> {
         span: Span,
         arg_data: InferenceDiagnosticsData,
         error_code: TypeAnnotationNeeded,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'_> {
         let source_kind = "other";
         let source_name = "";
         let failure_span = None;
@@ -436,7 +436,7 @@ impl<'tcx> InferCtxt<'tcx> {
     }
 }
 
-impl<'tcx> TypeErrCtxt<'_, 'tcx> {
+impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
     #[instrument(level = "debug", skip(self, error_code))]
     pub fn emit_inference_failure_err(
         &self,
@@ -445,7 +445,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         arg: GenericArg<'tcx>,
         error_code: TypeAnnotationNeeded,
         should_label_span: bool,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'a> {
         let arg = self.resolve_vars_if_possible(arg);
         let arg_data = self.extract_inference_diagnostics_data(arg, None);
 
@@ -453,7 +453,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
             // If we don't have any typeck results we're outside
             // of a body, so we won't be able to get better info
             // here.
-            return self.bad_inference_failure_err(failure_span, arg_data, error_code);
+            return self.infcx.bad_inference_failure_err(failure_span, arg_data, error_code);
         };
 
         let mut local_visitor = FindInferSourceVisitor::new(self, typeck_results, arg);
@@ -465,7 +465,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         }
 
         let Some(InferSource { span, kind }) = local_visitor.infer_source else {
-            return self.bad_inference_failure_err(failure_span, arg_data, error_code);
+            return self.infcx.bad_inference_failure_err(failure_span, arg_data, error_code);
         };
 
         let (source_kind, name, path) = kind.ty_localized_msg(self);
diff --git a/compiler/rustc_infer/src/infer/error_reporting/note.rs b/compiler/rustc_infer/src/infer/error_reporting/note.rs
index 8fd19563c30..d1fc9c9f140 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/note.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/note.rs
@@ -14,7 +14,7 @@ use rustc_span::symbol::kw;
 
 use super::ObligationCauseAsDiagArg;
 
-impl<'tcx> TypeErrCtxt<'_, 'tcx> {
+impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
     pub(super) fn note_region_origin(&self, err: &mut Diag<'_>, origin: &SubregionOrigin<'tcx>) {
         match *origin {
             infer::Subtype(ref trace) => RegionOriginNote::WithRequirement {
@@ -79,7 +79,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         origin: SubregionOrigin<'tcx>,
         sub: Region<'tcx>,
         sup: Region<'tcx>,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'a> {
         let mut err = match origin {
             infer::Subtype(box trace) => {
                 let terr = TypeError::RegionsDoesNotOutlive(sup, sub);
@@ -245,7 +245,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                 })
             }
             infer::CompareImplItemObligation { span, impl_item_def_id, trait_item_def_id } => {
-                let mut err = self.report_extra_impl_obligation(
+                let mut err = self.infcx.report_extra_impl_obligation(
                     span,
                     impl_item_def_id,
                     trait_item_def_id,
@@ -378,7 +378,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         placeholder_origin: SubregionOrigin<'tcx>,
         sub: Region<'tcx>,
         sup: Region<'tcx>,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'a> {
         // I can't think how to do better than this right now. -nikomatsakis
         debug!(?placeholder_origin, ?sub, ?sup, "report_placeholder_failure");
         match placeholder_origin {
diff --git a/compiler/rustc_infer/src/infer/mod.rs b/compiler/rustc_infer/src/infer/mod.rs
index a3cf588da1c..ff593d7ffb7 100644
--- a/compiler/rustc_infer/src/infer/mod.rs
+++ b/compiler/rustc_infer/src/infer/mod.rs
@@ -684,8 +684,8 @@ impl<'tcx> InferOk<'tcx, ()> {
 }
 
 impl<'tcx> InferCtxt<'tcx> {
-    pub fn dcx(&self) -> DiagCtxtHandle<'tcx> {
-        self.tcx.dcx()
+    pub fn dcx(&self) -> DiagCtxtHandle<'_> {
+        self.tcx.dcx().taintable_handle(&self.tainted_by_errors)
     }
 
     pub fn defining_opaque_types(&self) -> &'tcx ty::List<LocalDefId> {
@@ -1089,19 +1089,7 @@ impl<'tcx> InferCtxt<'tcx> {
     /// inference variables, regionck errors).
     #[must_use = "this method does not have any side effects"]
     pub fn tainted_by_errors(&self) -> Option<ErrorGuaranteed> {
-        if let Some(guar) = self.tainted_by_errors.get() {
-            Some(guar)
-        } else if self.dcx().err_count_excluding_lint_errs() > self.err_count_on_creation {
-            // Errors reported since this infcx was made. Lint errors are
-            // excluded to avoid some being swallowed in the presence of
-            // non-lint errors. (It's arguable whether or not this exclusion is
-            // important.)
-            let guar = self.dcx().has_errors().unwrap();
-            self.set_tainted_by_errors(guar);
-            Some(guar)
-        } else {
-            None
-        }
+        self.tainted_by_errors.get()
     }
 
     /// Set the "tainted by errors" flag to true. We call this when we
@@ -1328,8 +1316,7 @@ impl<'tcx> InferCtxt<'tcx> {
                     bug!("`{value:?}` is not fully resolved");
                 }
                 if value.has_infer_regions() {
-                    let guar =
-                        self.tcx.dcx().delayed_bug(format!("`{value:?}` is not fully resolved"));
+                    let guar = self.dcx().delayed_bug(format!("`{value:?}` is not fully resolved"));
                     Ok(self.tcx.fold_regions(value, |re, _| {
                         if re.is_var() { ty::Region::new_error(self.tcx, guar) } else { re }
                     }))
@@ -1607,7 +1594,7 @@ impl<'tcx> InferCtxt<'tcx> {
     }
 }
 
-impl<'tcx> TypeErrCtxt<'_, 'tcx> {
+impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
     // [Note-Type-error-reporting]
     // An invariant is that anytime the expected or actual type is Error (the special
     // error type, meaning that an error occurred when typechecking this expression),
@@ -1623,9 +1610,9 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         sp: Span,
         mk_diag: M,
         actual_ty: Ty<'tcx>,
-    ) -> Diag<'tcx>
+    ) -> Diag<'a>
     where
-        M: FnOnce(String) -> Diag<'tcx>,
+        M: FnOnce(String) -> Diag<'a>,
     {
         let actual_ty = self.resolve_vars_if_possible(actual_ty);
         debug!("type_error_struct_with_diag({:?}, {:?})", sp, actual_ty);
@@ -1646,7 +1633,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         expected: Ty<'tcx>,
         actual: Ty<'tcx>,
         err: TypeError<'tcx>,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'a> {
         self.report_and_explain_type_error(TypeTrace::types(cause, true, expected, actual), err)
     }
 
@@ -1656,7 +1643,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         expected: ty::Const<'tcx>,
         actual: ty::Const<'tcx>,
         err: TypeError<'tcx>,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'a> {
         self.report_and_explain_type_error(TypeTrace::consts(cause, true, expected, actual), err)
     }
 }
diff --git a/compiler/rustc_infer/src/infer/opaque_types/mod.rs b/compiler/rustc_infer/src/infer/opaque_types/mod.rs
index b8dd501a721..7c764cccc47 100644
--- a/compiler/rustc_infer/src/infer/opaque_types/mod.rs
+++ b/compiler/rustc_infer/src/infer/opaque_types/mod.rs
@@ -156,7 +156,7 @@ impl<'tcx> InferCtxt<'tcx> {
                     if self.can_define_opaque_ty(b_def_id)
                         && self.tcx.is_type_alias_impl_trait(b_def_id)
                     {
-                        self.tcx.dcx().emit_err(OpaqueHiddenTypeDiag {
+                        self.dcx().emit_err(OpaqueHiddenTypeDiag {
                             span,
                             hidden_type: self.tcx.def_span(b_def_id),
                             opaque_type: self.tcx.def_span(def_id),
diff --git a/compiler/rustc_infer/src/traits/error_reporting/mod.rs b/compiler/rustc_infer/src/traits/error_reporting/mod.rs
index 890e25368bc..7730fe29e09 100644
--- a/compiler/rustc_infer/src/traits/error_reporting/mod.rs
+++ b/compiler/rustc_infer/src/traits/error_reporting/mod.rs
@@ -12,15 +12,15 @@ use std::fmt;
 use std::iter;
 
 impl<'tcx> InferCtxt<'tcx> {
-    pub fn report_extra_impl_obligation(
-        &self,
+    pub fn report_extra_impl_obligation<'a>(
+        &'a self,
         error_span: Span,
         impl_item_def_id: LocalDefId,
         trait_item_def_id: DefId,
         requirement: &dyn fmt::Display,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'a> {
         let mut err = struct_span_code_err!(
-            self.tcx.dcx(),
+            self.dcx(),
             error_span,
             E0276,
             "impl has stricter requirements than trait"
diff --git a/compiler/rustc_infer/src/traits/util.rs b/compiler/rustc_infer/src/traits/util.rs
index ab4148faaab..24cf9f03fcd 100644
--- a/compiler/rustc_infer/src/traits/util.rs
+++ b/compiler/rustc_infer/src/traits/util.rs
@@ -275,10 +275,10 @@ impl<'tcx, O: Elaboratable<'tcx>> Elaborator<'tcx, O> {
                 }
                 // Get predicates implied by the trait, or only super predicates if we only care about self predicates.
                 let predicates = match self.mode {
-                    Filter::All => tcx.implied_predicates_of(data.def_id()),
-                    Filter::OnlySelf => tcx.super_predicates_of(data.def_id()),
+                    Filter::All => tcx.explicit_implied_predicates_of(data.def_id()),
+                    Filter::OnlySelf => tcx.explicit_super_predicates_of(data.def_id()),
                     Filter::OnlySelfThatDefines(ident) => {
-                        tcx.super_predicates_that_define_assoc_item((data.def_id(), ident))
+                        tcx.explicit_supertraits_containing_assoc_item((data.def_id(), ident))
                     }
                 };
 
@@ -420,7 +420,7 @@ pub fn transitive_bounds<'tcx>(
 
 /// A specialized variant of `elaborate` that only elaborates trait references that may
 /// define the given associated item with the name `assoc_name`. It uses the
-/// `super_predicates_that_define_assoc_item` query to avoid enumerating super-predicates that
+/// `explicit_supertraits_containing_assoc_item` query to avoid enumerating super-predicates that
 /// aren't related to `assoc_item`. This is used when resolving types like `Self::Item` or
 /// `T::Item` and helps to avoid cycle errors (see e.g. #35237).
 pub fn transitive_bounds_that_define_assoc_item<'tcx>(
diff --git a/compiler/rustc_interface/src/tests.rs b/compiler/rustc_interface/src/tests.rs
index 02322c9b282..9bd67a1154b 100644
--- a/compiler/rustc_interface/src/tests.rs
+++ b/compiler/rustc_interface/src/tests.rs
@@ -2,14 +2,22 @@
 use crate::interface::{initialize_checked_jobserver, parse_cfg};
 use rustc_data_structures::profiling::TimePassesFormat;
 use rustc_errors::{emitter::HumanReadableErrorType, registry, ColorConfig};
+use rustc_session::config::{build_configuration, build_session_options, rustc_optgroups};
 use rustc_session::config::{
-    build_configuration, build_session_options, rustc_optgroups, BranchProtection, CFGuard, Cfg,
-    CollapseMacroDebuginfo, CoverageLevel, CoverageOptions, DebugInfo, DumpMonoStatsFormat,
-    ErrorOutputType, ExternEntry, ExternLocation, Externs, FunctionReturn, InliningThreshold,
-    Input, InstrumentCoverage, InstrumentXRay, LinkSelfContained, LinkerPluginLto, LocationDetail,
-    LtoCli, NextSolverConfig, OomStrategy, Options, OutFileName, OutputType, OutputTypes, PAuthKey,
-    PacRet, Passes, PatchableFunctionEntry, Polonius, ProcMacroExecutionStrategy, Strip,
-    SwitchWithOptPath, SymbolManglingVersion, WasiExecModel,
+    BranchProtection, CFGuard, Cfg, CollapseMacroDebuginfo, CoverageLevel, CoverageOptions,
+    DebugInfo, DumpMonoStatsFormat, ErrorOutputType,
+};
+use rustc_session::config::{
+    ExternEntry, ExternLocation, Externs, FunctionReturn, InliningThreshold, Input,
+    InstrumentCoverage, InstrumentXRay, LinkSelfContained, LinkerPluginLto,
+};
+use rustc_session::config::{
+    LocationDetail, LtoCli, NextSolverConfig, OomStrategy, Options, OutFileName, OutputType,
+    OutputTypes, PAuthKey, PacRet, Passes, PatchableFunctionEntry,
+};
+use rustc_session::config::{
+    Polonius, ProcMacroExecutionStrategy, Strip, SwitchWithOptPath, SymbolManglingVersion,
+    WasiExecModel,
 };
 use rustc_session::lint::Level;
 use rustc_session::search_paths::SearchPath;
diff --git a/compiler/rustc_lint/messages.ftl b/compiler/rustc_lint/messages.ftl
index 46cf87d1e3c..3e952558d29 100644
--- a/compiler/rustc_lint/messages.ftl
+++ b/compiler/rustc_lint/messages.ftl
@@ -56,8 +56,6 @@ lint_builtin_asm_labels = avoid using named labels in inline assembly
     .help = only local labels of the form `<number>:` should be used in inline asm
     .note = see the asm section of Rust By Example <https://doc.rust-lang.org/nightly/rust-by-example/unsafe/asm.html#labels> for more information
 
-lint_builtin_box_pointers = type uses owned (Box type) pointers: {$ty}
-
 lint_builtin_clashing_extern_diff_name = `{$this}` redeclares `{$orig}` with a different signature
     .previous_decl_label = `{$orig}` previously declared here
     .mismatch_label = this signature doesn't match the previous declaration
diff --git a/compiler/rustc_lint/src/builtin.rs b/compiler/rustc_lint/src/builtin.rs
index 98318cd14d9..79c8046f9b7 100644
--- a/compiler/rustc_lint/src/builtin.rs
+++ b/compiler/rustc_lint/src/builtin.rs
@@ -24,9 +24,9 @@ use crate::fluent_generated as fluent;
 use crate::{
     errors::BuiltinEllipsisInclusiveRangePatterns,
     lints::{
-        BuiltinAnonymousParams, BuiltinBoxPointers, BuiltinConstNoMangle,
-        BuiltinDeprecatedAttrLink, BuiltinDeprecatedAttrLinkSuggestion, BuiltinDeprecatedAttrUsed,
-        BuiltinDerefNullptr, BuiltinEllipsisInclusiveRangePatternsLint, BuiltinExplicitOutlives,
+        BuiltinAnonymousParams, BuiltinConstNoMangle, BuiltinDeprecatedAttrLink,
+        BuiltinDeprecatedAttrLinkSuggestion, BuiltinDeprecatedAttrUsed, BuiltinDerefNullptr,
+        BuiltinEllipsisInclusiveRangePatternsLint, BuiltinExplicitOutlives,
         BuiltinExplicitOutlivesSuggestion, BuiltinFeatureIssueNote, BuiltinIncompleteFeatures,
         BuiltinIncompleteFeaturesHelp, BuiltinInternalFeatures, BuiltinKeywordIdents,
         BuiltinMissingCopyImpl, BuiltinMissingDebugImpl, BuiltinMissingDoc,
@@ -56,7 +56,6 @@ use rustc_middle::bug;
 use rustc_middle::lint::in_external_macro;
 use rustc_middle::ty::layout::LayoutOf;
 use rustc_middle::ty::print::with_no_trimmed_paths;
-use rustc_middle::ty::GenericArgKind;
 use rustc_middle::ty::TypeVisitableExt;
 use rustc_middle::ty::Upcast;
 use rustc_middle::ty::{self, Ty, TyCtxt, VariantDef};
@@ -135,80 +134,6 @@ impl EarlyLintPass for WhileTrue {
 }
 
 declare_lint! {
-    /// The `box_pointers` lints use of the Box type.
-    ///
-    /// ### Example
-    ///
-    /// ```rust,compile_fail
-    /// #![deny(box_pointers)]
-    /// struct Foo {
-    ///     x: Box<i32>,
-    /// }
-    /// ```
-    ///
-    /// {{produces}}
-    ///
-    /// ### Explanation
-    ///
-    /// This lint is mostly historical, and not particularly useful. `Box<T>`
-    /// used to be built into the language, and the only way to do heap
-    /// allocation. Today's Rust can call into other allocators, etc.
-    BOX_POINTERS,
-    Allow,
-    "use of owned (Box type) heap memory"
-}
-
-declare_lint_pass!(BoxPointers => [BOX_POINTERS]);
-
-impl BoxPointers {
-    fn check_heap_type(&self, cx: &LateContext<'_>, span: Span, ty: Ty<'_>) {
-        for leaf in ty.walk() {
-            if let GenericArgKind::Type(leaf_ty) = leaf.unpack()
-                && leaf_ty.is_box()
-            {
-                cx.emit_span_lint(BOX_POINTERS, span, BuiltinBoxPointers { ty });
-            }
-        }
-    }
-}
-
-impl<'tcx> LateLintPass<'tcx> for BoxPointers {
-    fn check_item(&mut self, cx: &LateContext<'_>, it: &hir::Item<'_>) {
-        match it.kind {
-            hir::ItemKind::Fn(..)
-            | hir::ItemKind::TyAlias(..)
-            | hir::ItemKind::Enum(..)
-            | hir::ItemKind::Struct(..)
-            | hir::ItemKind::Union(..) => self.check_heap_type(
-                cx,
-                it.span,
-                cx.tcx.type_of(it.owner_id).instantiate_identity(),
-            ),
-            _ => (),
-        }
-
-        // If it's a struct, we also have to check the fields' types
-        match it.kind {
-            hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => {
-                for field in struct_def.fields() {
-                    self.check_heap_type(
-                        cx,
-                        field.span,
-                        cx.tcx.type_of(field.def_id).instantiate_identity(),
-                    );
-                }
-            }
-            _ => (),
-        }
-    }
-
-    fn check_expr(&mut self, cx: &LateContext<'_>, e: &hir::Expr<'_>) {
-        let ty = cx.typeck_results().node_type(e.hir_id);
-        self.check_heap_type(cx, e.span, ty);
-    }
-}
-
-declare_lint! {
     /// The `non_shorthand_field_patterns` lint detects using `Struct { x: x }`
     /// instead of `Struct { x }` in a pattern.
     ///
@@ -1640,7 +1565,6 @@ declare_lint_pass!(
     /// which are used by other parts of the compiler.
     SoftLints => [
         WHILE_TRUE,
-        BOX_POINTERS,
         NON_SHORTHAND_FIELD_PATTERNS,
         UNSAFE_CODE,
         MISSING_DOCS,
diff --git a/compiler/rustc_lint/src/lib.rs b/compiler/rustc_lint/src/lib.rs
index 7dae2de7bfb..17f9d4421ae 100644
--- a/compiler/rustc_lint/src/lib.rs
+++ b/compiler/rustc_lint/src/lib.rs
@@ -187,7 +187,6 @@ late_lint_methods!(
             ImproperCTypesDefinitions: ImproperCTypesDefinitions,
             InvalidFromUtf8: InvalidFromUtf8,
             VariantSizeDifferences: VariantSizeDifferences,
-            BoxPointers: BoxPointers,
             PathStatements: PathStatements,
             LetUnderscore: LetUnderscore,
             InvalidReferenceCasting: InvalidReferenceCasting,
@@ -551,6 +550,10 @@ fn register_builtins(store: &mut LintStore) {
         "converted into hard error, see RFC #3535 \
          <https://rust-lang.github.io/rfcs/3535-constants-in-patterns.html> for more information",
     );
+    store.register_removed(
+        "box_pointers",
+        "it does not detect other kinds of allocations, and existed only for historical reasons",
+    );
 }
 
 fn register_internals(store: &mut LintStore) {
diff --git a/compiler/rustc_lint/src/lints.rs b/compiler/rustc_lint/src/lints.rs
index 14084405d0e..7c5640f5959 100644
--- a/compiler/rustc_lint/src/lints.rs
+++ b/compiler/rustc_lint/src/lints.rs
@@ -67,12 +67,6 @@ pub struct BuiltinWhileTrue {
 }
 
 #[derive(LintDiagnostic)]
-#[diag(lint_builtin_box_pointers)]
-pub struct BuiltinBoxPointers<'a> {
-    pub ty: Ty<'a>,
-}
-
-#[derive(LintDiagnostic)]
 #[diag(lint_builtin_non_shorthand_field_patterns)]
 pub struct BuiltinNonShorthandFieldPatterns {
     pub ident: Ident,
diff --git a/compiler/rustc_lint/src/multiple_supertrait_upcastable.rs b/compiler/rustc_lint/src/multiple_supertrait_upcastable.rs
index aa1d94228ea..445dcd41e5d 100644
--- a/compiler/rustc_lint/src/multiple_supertrait_upcastable.rs
+++ b/compiler/rustc_lint/src/multiple_supertrait_upcastable.rs
@@ -45,7 +45,7 @@ impl<'tcx> LateLintPass<'tcx> for MultipleSupertraitUpcastable {
         {
             let direct_super_traits_iter = cx
                 .tcx
-                .super_predicates_of(def_id)
+                .explicit_super_predicates_of(def_id)
                 .predicates
                 .into_iter()
                 .filter_map(|(pred, _)| pred.as_trait_clause());
diff --git a/compiler/rustc_lint/src/non_local_def.rs b/compiler/rustc_lint/src/non_local_def.rs
index 300dac442d5..17429ed061f 100644
--- a/compiler/rustc_lint/src/non_local_def.rs
+++ b/compiler/rustc_lint/src/non_local_def.rs
@@ -50,7 +50,7 @@ declare_lint! {
     /// All nested bodies (functions, enum discriminant, array length, consts) (expect for
     /// `const _: Ty = { ... }` in top-level module, which is still undecided) are checked.
     pub NON_LOCAL_DEFINITIONS,
-    Warn,
+    Allow,
     "checks for non-local definitions",
     report_in_external_macro
 }
diff --git a/compiler/rustc_lint_defs/src/builtin.rs b/compiler/rustc_lint_defs/src/builtin.rs
index 472e93d202d..2ade6964ca8 100644
--- a/compiler/rustc_lint_defs/src/builtin.rs
+++ b/compiler/rustc_lint_defs/src/builtin.rs
@@ -74,6 +74,7 @@ declare_lint_pass! {
         NON_CONTIGUOUS_RANGE_ENDPOINTS,
         NON_EXHAUSTIVE_OMITTED_PATTERNS,
         ORDER_DEPENDENT_TRAIT_OBJECTS,
+        OUT_OF_SCOPE_MACRO_CALLS,
         OVERLAPPING_RANGE_ENDPOINTS,
         PATTERNS_IN_FNS_WITHOUT_BODY,
         PRIVATE_BOUNDS,
diff --git a/compiler/rustc_metadata/src/rmeta/decoder.rs b/compiler/rustc_metadata/src/rmeta/decoder.rs
index ea7037740f1..83b41e0540e 100644
--- a/compiler/rustc_metadata/src/rmeta/decoder.rs
+++ b/compiler/rustc_metadata/src/rmeta/decoder.rs
@@ -1348,7 +1348,9 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
     }
 
     fn get_associated_item(self, id: DefIndex, sess: &'a Session) -> ty::AssocItem {
-        let name = if self.root.tables.opt_rpitit_info.get(self, id).is_some() {
+        let name = if self.root.tables.opt_rpitit_info.get(self, id).is_some()
+            || self.root.tables.is_effects_desugaring.get(self, id)
+        {
             kw::Empty
         } else {
             self.item_name(id)
@@ -1371,6 +1373,7 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
             container,
             fn_has_self_parameter: has_self,
             opt_rpitit_info,
+            is_effects_desugaring: self.root.tables.is_effects_desugaring.get(self, id),
         }
     }
 
diff --git a/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs b/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
index c9450142cd3..6b240f0f0b3 100644
--- a/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
+++ b/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
@@ -211,8 +211,8 @@ provide! { tcx, def_id, other, cdata,
     explicit_predicates_of => { table }
     generics_of => { table }
     inferred_outlives_of => { table_defaulted_array }
-    super_predicates_of => { table }
-    implied_predicates_of => { table }
+    explicit_super_predicates_of => { table }
+    explicit_implied_predicates_of => { table }
     type_of => { table }
     type_alias_is_lazy => { cdata.root.tables.type_alias_is_lazy.get(cdata, def_id.index) }
     variances_of => { table }
@@ -279,6 +279,9 @@ provide! { tcx, def_id, other, cdata,
             .process_decoded(tcx, || panic!("{def_id:?} does not have trait_impl_trait_tys")))
     }
 
+    associated_type_for_effects => {
+        table
+    }
     associated_types_for_impl_traits_in_associated_fn => { table_defaulted_array }
 
     visibility => { cdata.get_visibility(def_id.index) }
diff --git a/compiler/rustc_metadata/src/rmeta/encoder.rs b/compiler/rustc_metadata/src/rmeta/encoder.rs
index 4bd2ec09a6e..209316ca20f 100644
--- a/compiler/rustc_metadata/src/rmeta/encoder.rs
+++ b/compiler/rustc_metadata/src/rmeta/encoder.rs
@@ -1431,8 +1431,8 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
             }
             if let DefKind::Trait = def_kind {
                 record!(self.tables.trait_def[def_id] <- self.tcx.trait_def(def_id));
-                record!(self.tables.super_predicates_of[def_id] <- self.tcx.super_predicates_of(def_id));
-                record!(self.tables.implied_predicates_of[def_id] <- self.tcx.implied_predicates_of(def_id));
+                record!(self.tables.explicit_super_predicates_of[def_id] <- self.tcx.explicit_super_predicates_of(def_id));
+                record!(self.tables.explicit_implied_predicates_of[def_id] <- self.tcx.explicit_implied_predicates_of(def_id));
 
                 let module_children = self.tcx.module_children_local(local_id);
                 record_array!(self.tables.module_children_non_reexports[def_id] <-
@@ -1440,8 +1440,8 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
             }
             if let DefKind::TraitAlias = def_kind {
                 record!(self.tables.trait_def[def_id] <- self.tcx.trait_def(def_id));
-                record!(self.tables.super_predicates_of[def_id] <- self.tcx.super_predicates_of(def_id));
-                record!(self.tables.implied_predicates_of[def_id] <- self.tcx.implied_predicates_of(def_id));
+                record!(self.tables.explicit_super_predicates_of[def_id] <- self.tcx.explicit_super_predicates_of(def_id));
+                record!(self.tables.explicit_implied_predicates_of[def_id] <- self.tcx.explicit_implied_predicates_of(def_id));
             }
             if let DefKind::Trait | DefKind::Impl { .. } = def_kind {
                 let associated_item_def_ids = self.tcx.associated_item_def_ids(def_id);
@@ -1454,6 +1454,9 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
                 for &def_id in associated_item_def_ids {
                     self.encode_info_for_assoc_item(def_id);
                 }
+                if let Some(assoc_def_id) = self.tcx.associated_type_for_effects(def_id) {
+                    record!(self.tables.associated_type_for_effects[def_id] <- assoc_def_id);
+                }
             }
             if def_kind == DefKind::Closure
                 && let Some(coroutine_kind) = self.tcx.coroutine_kind(def_id)
@@ -1634,6 +1637,9 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
                 );
             }
         }
+        if item.is_effects_desugaring {
+            self.tables.is_effects_desugaring.set(def_id.index, true);
+        }
     }
 
     fn encode_mir(&mut self) {
diff --git a/compiler/rustc_metadata/src/rmeta/mod.rs b/compiler/rustc_metadata/src/rmeta/mod.rs
index 87900c23d8d..2a44b3423ae 100644
--- a/compiler/rustc_metadata/src/rmeta/mod.rs
+++ b/compiler/rustc_metadata/src/rmeta/mod.rs
@@ -391,7 +391,9 @@ define_tables! {
     inferred_outlives_of: Table<DefIndex, LazyArray<(ty::Clause<'static>, Span)>>,
     inherent_impls: Table<DefIndex, LazyArray<DefIndex>>,
     associated_types_for_impl_traits_in_associated_fn: Table<DefIndex, LazyArray<DefId>>,
+    associated_type_for_effects: Table<DefIndex, Option<LazyValue<DefId>>>,
     opt_rpitit_info: Table<DefIndex, Option<LazyValue<ty::ImplTraitInTraitData>>>,
+    is_effects_desugaring: Table<DefIndex, bool>,
     unused_generic_params: Table<DefIndex, UnusedGenericParams>,
     // Reexported names are not associated with individual `DefId`s,
     // e.g. a glob import can introduce a lot of names, all with the same `DefId`.
@@ -416,10 +418,10 @@ define_tables! {
     lookup_deprecation_entry: Table<DefIndex, LazyValue<attr::Deprecation>>,
     explicit_predicates_of: Table<DefIndex, LazyValue<ty::GenericPredicates<'static>>>,
     generics_of: Table<DefIndex, LazyValue<ty::Generics>>,
-    super_predicates_of: Table<DefIndex, LazyValue<ty::GenericPredicates<'static>>>,
+    explicit_super_predicates_of: Table<DefIndex, LazyValue<ty::GenericPredicates<'static>>>,
     // As an optimization, we only store this for trait aliases,
-    // since it's identical to super_predicates_of for traits.
-    implied_predicates_of: Table<DefIndex, LazyValue<ty::GenericPredicates<'static>>>,
+    // since it's identical to explicit_super_predicates_of for traits.
+    explicit_implied_predicates_of: Table<DefIndex, LazyValue<ty::GenericPredicates<'static>>>,
     type_of: Table<DefIndex, LazyValue<ty::EarlyBinder<'static, Ty<'static>>>>,
     variances_of: Table<DefIndex, LazyArray<ty::Variance>>,
     fn_sig: Table<DefIndex, LazyValue<ty::EarlyBinder<'static, ty::PolyFnSig<'static>>>>,
diff --git a/compiler/rustc_middle/src/query/mod.rs b/compiler/rustc_middle/src/query/mod.rs
index 230a44bcf24..d40a7833589 100644
--- a/compiler/rustc_middle/src/query/mod.rs
+++ b/compiler/rustc_middle/src/query/mod.rs
@@ -368,6 +368,7 @@ rustc_queries! {
         desc { |tcx| "finding item bounds for `{}`", tcx.def_path_str(key) }
         cache_on_disk_if { key.is_local() }
         separate_provide_extern
+        feedable
     }
 
     /// The set of item bounds (see [`TyCtxt::explicit_item_bounds`]) that
@@ -378,6 +379,7 @@ rustc_queries! {
         desc { |tcx| "finding item bounds for `{}`", tcx.def_path_str(key) }
         cache_on_disk_if { key.is_local() }
         separate_provide_extern
+        feedable
     }
 
     /// Elaborated version of the predicates from `explicit_item_bounds`.
@@ -646,6 +648,9 @@ rustc_queries! {
     }
 
     /// Returns the predicates written explicitly by the user.
+    ///
+    /// You should probably use `predicates_of` unless you're looking for
+    /// predicates with explicit spans for diagnostics purposes.
     query explicit_predicates_of(key: DefId) -> ty::GenericPredicates<'tcx> {
         desc { |tcx| "computing explicit predicates of `{}`", tcx.def_path_str(key) }
         cache_on_disk_if { key.is_local() }
@@ -662,29 +667,32 @@ rustc_queries! {
         feedable
     }
 
-    /// Maps from the `DefId` of a trait to the list of
-    /// super-predicates. This is a subset of the full list of
-    /// predicates. We store these in a separate map because we must
-    /// evaluate them even during type conversion, often before the
-    /// full predicates are available (note that supertraits have
-    /// additional acyclicity requirements).
-    query super_predicates_of(key: DefId) -> ty::GenericPredicates<'tcx> {
+    /// Maps from the `DefId` of a trait to the list of super-predicates of the trait,
+    /// *before* elaboration (so it doesn't contain transitive super-predicates). This
+    /// is a subset of the full list of predicates. We store these in a separate map
+    /// because we must evaluate them even during type conversion, often before the full
+    /// predicates are available (note that super-predicates must not be cyclic).
+    query explicit_super_predicates_of(key: DefId) -> ty::GenericPredicates<'tcx> {
         desc { |tcx| "computing the super predicates of `{}`", tcx.def_path_str(key) }
         cache_on_disk_if { key.is_local() }
         separate_provide_extern
     }
 
-    query implied_predicates_of(key: DefId) -> ty::GenericPredicates<'tcx> {
+    /// The predicates of the trait that are implied during elaboration. This is a
+    /// superset of the super-predicates of the trait, but a subset of the predicates
+    /// of the trait. For regular traits, this includes all super-predicates and their
+    /// associated type bounds. For trait aliases, currently, this includes all of the
+    /// predicates of the trait alias.
+    query explicit_implied_predicates_of(key: DefId) -> ty::GenericPredicates<'tcx> {
         desc { |tcx| "computing the implied predicates of `{}`", tcx.def_path_str(key) }
         cache_on_disk_if { key.is_local() }
         separate_provide_extern
     }
 
-    /// The `Option<Ident>` is the name of an associated type. If it is `None`, then this query
-    /// returns the full set of predicates. If `Some<Ident>`, then the query returns only the
-    /// subset of super-predicates that reference traits that define the given associated type.
-    /// This is used to avoid cycles in resolving types like `T::Item`.
-    query super_predicates_that_define_assoc_item(key: (DefId, rustc_span::symbol::Ident)) -> ty::GenericPredicates<'tcx> {
+    /// The Ident is the name of an associated type.The query returns only the subset
+    /// of supertraits that define the given associated type. This is used to avoid
+    /// cycles in resolving type-dependent associated item paths like `T::Item`.
+    query explicit_supertraits_containing_assoc_item(key: (DefId, rustc_span::symbol::Ident)) -> ty::GenericPredicates<'tcx> {
         desc { |tcx| "computing the super traits of `{}` with associated type name `{}`",
             tcx.def_path_str(key.0),
             key.1
@@ -847,6 +855,12 @@ rustc_queries! {
         separate_provide_extern
     }
 
+    query associated_type_for_effects(def_id: DefId) -> Option<DefId> {
+        desc { |tcx| "creating associated items for effects in `{}`", tcx.def_path_str(def_id) }
+        cache_on_disk_if { def_id.is_local() }
+        separate_provide_extern
+    }
+
     /// Given an impl trait in trait `opaque_ty_def_id`, create and return the corresponding
     /// associated item.
     query associated_type_for_impl_trait_in_trait(opaque_ty_def_id: LocalDefId) -> LocalDefId {
diff --git a/compiler/rustc_middle/src/traits/util.rs b/compiler/rustc_middle/src/traits/util.rs
index adbb6cf2ddc..7437be7a74c 100644
--- a/compiler/rustc_middle/src/traits/util.rs
+++ b/compiler/rustc_middle/src/traits/util.rs
@@ -35,7 +35,7 @@ struct Elaborator<'tcx> {
 impl<'tcx> Elaborator<'tcx> {
     fn elaborate(&mut self, trait_ref: PolyTraitRef<'tcx>) {
         let super_predicates =
-            self.tcx.super_predicates_of(trait_ref.def_id()).predicates.iter().filter_map(
+            self.tcx.explicit_super_predicates_of(trait_ref.def_id()).predicates.iter().filter_map(
                 |&(pred, _)| {
                     let clause = pred.instantiate_supertrait(self.tcx, trait_ref);
                     self.visited.insert(clause).then_some(clause)
diff --git a/compiler/rustc_middle/src/ty/assoc.rs b/compiler/rustc_middle/src/ty/assoc.rs
index 1cdde3f057c..820f5e950a9 100644
--- a/compiler/rustc_middle/src/ty/assoc.rs
+++ b/compiler/rustc_middle/src/ty/assoc.rs
@@ -34,6 +34,8 @@ pub struct AssocItem {
     /// return-position `impl Trait` in trait desugaring. The `ImplTraitInTraitData`
     /// provides additional information about its source.
     pub opt_rpitit_info: Option<ty::ImplTraitInTraitData>,
+
+    pub is_effects_desugaring: bool,
 }
 
 impl AssocItem {
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index 4bac9396e59..9225ae6300f 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -342,12 +342,15 @@ impl<'tcx> Interner for TyCtxt<'tcx> {
         )
     }
 
-    fn super_predicates_of(
+    fn explicit_super_predicates_of(
         self,
         def_id: DefId,
     ) -> ty::EarlyBinder<'tcx, impl IntoIterator<Item = ty::Clause<'tcx>>> {
         ty::EarlyBinder::bind(
-            self.super_predicates_of(def_id).instantiate_identity(self).predicates.into_iter(),
+            self.explicit_super_predicates_of(def_id)
+                .instantiate_identity(self)
+                .predicates
+                .into_iter(),
         )
     }
 
@@ -598,6 +601,11 @@ fn trait_lang_item_to_lang_item(lang_item: TraitSolverLangItem) -> LangItem {
         TraitSolverLangItem::Destruct => LangItem::Destruct,
         TraitSolverLangItem::DiscriminantKind => LangItem::DiscriminantKind,
         TraitSolverLangItem::DynMetadata => LangItem::DynMetadata,
+        TraitSolverLangItem::EffectsMaybe => LangItem::EffectsMaybe,
+        TraitSolverLangItem::EffectsIntersection => LangItem::EffectsIntersection,
+        TraitSolverLangItem::EffectsIntersectionOutput => LangItem::EffectsIntersectionOutput,
+        TraitSolverLangItem::EffectsNoRuntime => LangItem::EffectsNoRuntime,
+        TraitSolverLangItem::EffectsRuntime => LangItem::EffectsRuntime,
         TraitSolverLangItem::FnPtrTrait => LangItem::FnPtrTrait,
         TraitSolverLangItem::FusedIterator => LangItem::FusedIterator,
         TraitSolverLangItem::Future => LangItem::Future,
@@ -2440,7 +2448,7 @@ impl<'tcx> TyCtxt<'tcx> {
     /// Given the def_id of a Trait `trait_def_id` and the name of an associated item `assoc_name`
     /// returns true if the `trait_def_id` defines an associated item of name `assoc_name`.
     pub fn trait_may_define_assoc_item(self, trait_def_id: DefId, assoc_name: Ident) -> bool {
-        self.super_traits_of(trait_def_id).any(|trait_did| {
+        self.supertrait_def_ids(trait_def_id).any(|trait_did| {
             self.associated_items(trait_did)
                 .filter_by_name_unhygienic(assoc_name.name)
                 .any(|item| self.hygienic_eq(assoc_name, item.ident(self), trait_did))
@@ -2463,9 +2471,9 @@ impl<'tcx> TyCtxt<'tcx> {
 
     /// Computes the def-ids of the transitive supertraits of `trait_def_id`. This (intentionally)
     /// does not compute the full elaborated super-predicates but just the set of def-ids. It is used
-    /// to identify which traits may define a given associated type to help avoid cycle errors.
-    /// Returns a `DefId` iterator.
-    fn super_traits_of(self, trait_def_id: DefId) -> impl Iterator<Item = DefId> + 'tcx {
+    /// to identify which traits may define a given associated type to help avoid cycle errors,
+    /// and to make size estimates for vtable layout computation.
+    pub fn supertrait_def_ids(self, trait_def_id: DefId) -> impl Iterator<Item = DefId> + 'tcx {
         let mut set = FxHashSet::default();
         let mut stack = vec![trait_def_id];
 
@@ -2473,7 +2481,7 @@ impl<'tcx> TyCtxt<'tcx> {
 
         iter::from_fn(move || -> Option<DefId> {
             let trait_did = stack.pop()?;
-            let generic_predicates = self.super_predicates_of(trait_did);
+            let generic_predicates = self.explicit_super_predicates_of(trait_did);
 
             for (predicate, _) in generic_predicates.predicates {
                 if let ty::ClauseKind::Trait(data) = predicate.kind().skip_binder() {
@@ -3095,9 +3103,9 @@ impl<'tcx> TyCtxt<'tcx> {
         matches!(
             node,
             hir::Node::Item(hir::Item {
-                kind: hir::ItemKind::Impl(hir::Impl { generics, .. }),
+                kind: hir::ItemKind::Impl(hir::Impl { constness, .. }),
                 ..
-            }) if generics.params.iter().any(|p| matches!(p.kind, hir::GenericParamKind::Const { is_host_effect: true, .. }))
+            }) if matches!(constness, hir::Constness::Const)
         )
     }
 
diff --git a/compiler/rustc_middle/src/ty/generics.rs b/compiler/rustc_middle/src/ty/generics.rs
index 6467689a8aa..844023df1e3 100644
--- a/compiler/rustc_middle/src/ty/generics.rs
+++ b/compiler/rustc_middle/src/ty/generics.rs
@@ -14,7 +14,7 @@ use super::{Clause, InstantiatedPredicates, ParamConst, ParamTy, Ty, TyCtxt};
 pub enum GenericParamDefKind {
     Lifetime,
     Type { has_default: bool, synthetic: bool },
-    Const { has_default: bool, is_host_effect: bool },
+    Const { has_default: bool, is_host_effect: bool, synthetic: bool },
 }
 
 impl GenericParamDefKind {
@@ -371,6 +371,7 @@ impl<'tcx> Generics {
 pub struct GenericPredicates<'tcx> {
     pub parent: Option<DefId>,
     pub predicates: &'tcx [(Clause<'tcx>, Span)],
+    pub effects_min_tys: &'tcx ty::List<Ty<'tcx>>,
 }
 
 impl<'tcx> GenericPredicates<'tcx> {
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index 9c2bfc12a18..7d57d88f40f 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -1608,7 +1608,7 @@ impl<'tcx> TyCtxt<'tcx> {
         }
     }
 
-    /// If the def-id is an associated type that was desugared from a
+    /// If the `def_id` is an associated type that was desugared from a
     /// return-position `impl Trait` from a trait, then provide the source info
     /// about where that RPITIT came from.
     pub fn opt_rpitit_info(self, def_id: DefId) -> Option<ImplTraitInTraitData> {
@@ -1619,6 +1619,16 @@ impl<'tcx> TyCtxt<'tcx> {
         }
     }
 
+    /// Whether the `def_id` is an associated type that was desugared from a
+    /// `#[const_trait]` or `impl_const`.
+    pub fn is_effects_desugared_assoc_ty(self, def_id: DefId) -> bool {
+        if let DefKind::AssocTy = self.def_kind(def_id) {
+            self.associated_item(def_id).is_effects_desugaring
+        } else {
+            false
+        }
+    }
+
     pub fn find_field_index(self, ident: Ident, variant: &VariantDef) -> Option<FieldIdx> {
         variant.fields.iter_enumerated().find_map(|(i, field)| {
             self.hygienic_eq(ident, field.ident(self), variant.def_id).then_some(i)
diff --git a/compiler/rustc_middle/src/ty/vtable.rs b/compiler/rustc_middle/src/ty/vtable.rs
index dc3c84f9e43..466c3b93f8e 100644
--- a/compiler/rustc_middle/src/ty/vtable.rs
+++ b/compiler/rustc_middle/src/ty/vtable.rs
@@ -3,8 +3,6 @@ use std::fmt;
 use crate::mir::interpret::{alloc_range, AllocId, Allocation, Pointer, Scalar};
 use crate::ty::{self, Instance, PolyTraitRef, Ty, TyCtxt};
 use rustc_ast::Mutability;
-use rustc_data_structures::fx::FxHashSet;
-use rustc_hir::def_id::DefId;
 use rustc_macros::HashStable;
 
 #[derive(Clone, Copy, PartialEq, HashStable)]
@@ -42,45 +40,12 @@ impl<'tcx> fmt::Debug for VtblEntry<'tcx> {
 impl<'tcx> TyCtxt<'tcx> {
     pub const COMMON_VTABLE_ENTRIES: &'tcx [VtblEntry<'tcx>] =
         &[VtblEntry::MetadataDropInPlace, VtblEntry::MetadataSize, VtblEntry::MetadataAlign];
-
-    pub fn supertrait_def_ids(self, trait_def_id: DefId) -> SupertraitDefIds<'tcx> {
-        SupertraitDefIds {
-            tcx: self,
-            stack: vec![trait_def_id],
-            visited: Some(trait_def_id).into_iter().collect(),
-        }
-    }
 }
 
 pub const COMMON_VTABLE_ENTRIES_DROPINPLACE: usize = 0;
 pub const COMMON_VTABLE_ENTRIES_SIZE: usize = 1;
 pub const COMMON_VTABLE_ENTRIES_ALIGN: usize = 2;
 
-pub struct SupertraitDefIds<'tcx> {
-    tcx: TyCtxt<'tcx>,
-    stack: Vec<DefId>,
-    visited: FxHashSet<DefId>,
-}
-
-impl Iterator for SupertraitDefIds<'_> {
-    type Item = DefId;
-
-    fn next(&mut self) -> Option<DefId> {
-        let def_id = self.stack.pop()?;
-        let predicates = self.tcx.super_predicates_of(def_id);
-        let visited = &mut self.visited;
-        self.stack.extend(
-            predicates
-                .predicates
-                .iter()
-                .filter_map(|(pred, _)| pred.as_trait_clause())
-                .map(|trait_ref| trait_ref.def_id())
-                .filter(|&super_def_id| visited.insert(super_def_id)),
-        );
-        Some(def_id)
-    }
-}
-
 // Note that we don't have access to a self type here, this has to be purely based on the trait (and
 // supertrait) definitions. That means we can't call into the same vtable_entries code since that
 // returns a specific instantiation (e.g., with Vacant slots when bounds aren't satisfied). The goal
diff --git a/compiler/rustc_mir_build/src/build/block.rs b/compiler/rustc_mir_build/src/build/block.rs
index c1d645aa42c..5ccbd7c59cf 100644
--- a/compiler/rustc_mir_build/src/build/block.rs
+++ b/compiler/rustc_mir_build/src/build/block.rs
@@ -1,3 +1,4 @@
+use crate::build::matches::{DeclareLetBindings, EmitStorageLive, ScheduleDrops};
 use crate::build::ForGuard::OutsideGuard;
 use crate::build::{BlockAnd, BlockAndExtension, BlockFrame, Builder};
 use rustc_middle::middle::region::Scope;
@@ -189,38 +190,43 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
 
                     let initializer_span = this.thir[*initializer].span;
                     let scope = (*init_scope, source_info);
-                    let failure = unpack!(
-                        block = this.in_scope(scope, *lint_level, |this| {
-                            this.declare_bindings(
-                                visibility_scope,
-                                remainder_span,
-                                pattern,
-                                None,
-                                Some((Some(&destination), initializer_span)),
-                            );
-                            this.visit_primary_bindings(
-                                pattern,
-                                UserTypeProjections::none(),
-                                &mut |this, _, _, node, span, _, _| {
-                                    this.storage_live_binding(
-                                        block,
-                                        node,
-                                        span,
-                                        OutsideGuard,
-                                        true,
-                                    );
-                                },
-                            );
-                            this.ast_let_else(
-                                block,
-                                *initializer,
-                                initializer_span,
-                                *else_block,
-                                &last_remainder_scope,
-                                pattern,
-                            )
-                        })
-                    );
+                    let failure_and_block = this.in_scope(scope, *lint_level, |this| {
+                        this.declare_bindings(
+                            visibility_scope,
+                            remainder_span,
+                            pattern,
+                            None,
+                            Some((Some(&destination), initializer_span)),
+                        );
+                        this.visit_primary_bindings(
+                            pattern,
+                            UserTypeProjections::none(),
+                            &mut |this, _, _, node, span, _, _| {
+                                this.storage_live_binding(
+                                    block,
+                                    node,
+                                    span,
+                                    OutsideGuard,
+                                    ScheduleDrops::Yes,
+                                );
+                            },
+                        );
+                        let else_block_span = this.thir[*else_block].span;
+                        let (matching, failure) =
+                            this.in_if_then_scope(last_remainder_scope, else_block_span, |this| {
+                                this.lower_let_expr(
+                                    block,
+                                    *initializer,
+                                    pattern,
+                                    None,
+                                    initializer_span,
+                                    DeclareLetBindings::No,
+                                    EmitStorageLive::No,
+                                )
+                            });
+                        matching.and(failure)
+                    });
+                    let failure = unpack!(block = failure_and_block);
                     this.cfg.goto(failure, source_info, failure_entry);
 
                     if let Some(source_scope) = visibility_scope {
@@ -292,7 +298,13 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                             pattern,
                             UserTypeProjections::none(),
                             &mut |this, _, _, node, span, _, _| {
-                                this.storage_live_binding(block, node, span, OutsideGuard, true);
+                                this.storage_live_binding(
+                                    block,
+                                    node,
+                                    span,
+                                    OutsideGuard,
+                                    ScheduleDrops::Yes,
+                                );
                                 this.schedule_drop_for_binding(node, span, OutsideGuard);
                             },
                         )
diff --git a/compiler/rustc_mir_build/src/build/expr/into.rs b/compiler/rustc_mir_build/src/build/expr/into.rs
index 76bdc26a501..942c69b5c0a 100644
--- a/compiler/rustc_mir_build/src/build/expr/into.rs
+++ b/compiler/rustc_mir_build/src/build/expr/into.rs
@@ -1,6 +1,7 @@
 //! See docs in build/expr/mod.rs
 
 use crate::build::expr::category::{Category, RvalueFunc};
+use crate::build::matches::DeclareLetBindings;
 use crate::build::{BlockAnd, BlockAndExtension, BlockFrame, Builder, NeedsTemporary};
 use rustc_ast::InlineAsmOptions;
 use rustc_data_structures::fx::FxHashMap;
@@ -86,7 +87,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                                     cond,
                                     Some(condition_scope), // Temp scope
                                     source_info,
-                                    true, // Declare `let` bindings normally
+                                    DeclareLetBindings::Yes, // Declare `let` bindings normally
                                 ));
 
                                 // Lower the `then` arm into its block.
@@ -163,7 +164,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                             source_info,
                             // This flag controls how inner `let` expressions are lowered,
                             // but either way there shouldn't be any of those in here.
-                            true,
+                            DeclareLetBindings::LetNotPermitted,
                         )
                     });
                 let (short_circuit, continuation, constant) = match op {
diff --git a/compiler/rustc_mir_build/src/build/matches/mod.rs b/compiler/rustc_mir_build/src/build/matches/mod.rs
index 932406fd1aa..efed52231e3 100644
--- a/compiler/rustc_mir_build/src/build/matches/mod.rs
+++ b/compiler/rustc_mir_build/src/build/matches/mod.rs
@@ -21,12 +21,14 @@ use rustc_span::symbol::Symbol;
 use rustc_span::{BytePos, Pos, Span};
 use rustc_target::abi::VariantIdx;
 use tracing::{debug, instrument};
+use util::visit_bindings;
 
 // helper functions, broken out by category:
 mod simplify;
 mod test;
 mod util;
 
+use std::assert_matches::assert_matches;
 use std::borrow::Borrow;
 use std::mem;
 
@@ -38,9 +40,50 @@ struct ThenElseArgs {
     /// `self.local_scope()` is used.
     temp_scope_override: Option<region::Scope>,
     variable_source_info: SourceInfo,
+    /// Determines how bindings should be handled when lowering `let` expressions.
+    ///
     /// Forwarded to [`Builder::lower_let_expr`] when lowering [`ExprKind::Let`].
-    /// When false (for match guards), `let` bindings won't be declared.
-    declare_let_bindings: bool,
+    declare_let_bindings: DeclareLetBindings,
+}
+
+/// Should lowering a `let` expression also declare its bindings?
+///
+/// Used by [`Builder::lower_let_expr`] when lowering [`ExprKind::Let`].
+#[derive(Clone, Copy)]
+pub(crate) enum DeclareLetBindings {
+    /// Yes, declare `let` bindings as normal for `if` conditions.
+    Yes,
+    /// No, don't declare `let` bindings, because the caller declares them
+    /// separately due to special requirements.
+    ///
+    /// Used for match guards and let-else.
+    No,
+    /// Let expressions are not permitted in this context, so it is a bug to
+    /// try to lower one (e.g inside lazy-boolean-or or boolean-not).
+    LetNotPermitted,
+}
+
+/// Used by [`Builder::bind_matched_candidate_for_arm_body`] to determine
+/// whether or not to call [`Builder::storage_live_binding`] to emit
+/// [`StatementKind::StorageLive`].
+#[derive(Clone, Copy)]
+pub(crate) enum EmitStorageLive {
+    /// Yes, emit `StorageLive` as normal.
+    Yes,
+    /// No, don't emit `StorageLive`. The caller has taken responsibility for
+    /// emitting `StorageLive` as appropriate.
+    No,
+}
+
+/// Used by [`Builder::storage_live_binding`] and [`Builder::bind_matched_candidate_for_arm_body`]
+/// to decide whether to schedule drops.
+#[derive(Clone, Copy, Debug)]
+pub(crate) enum ScheduleDrops {
+    /// Yes, the relevant functions should also schedule drops as appropriate.
+    Yes,
+    /// No, don't schedule drops. The caller has taken responsibility for any
+    /// appropriate drops.
+    No,
 }
 
 impl<'a, 'tcx> Builder<'a, 'tcx> {
@@ -56,7 +99,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         expr_id: ExprId,
         temp_scope_override: Option<region::Scope>,
         variable_source_info: SourceInfo,
-        declare_let_bindings: bool,
+        declare_let_bindings: DeclareLetBindings,
     ) -> BlockAnd<()> {
         self.then_else_break_inner(
             block,
@@ -90,13 +133,19 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                         this.then_else_break_inner(
                             block,
                             lhs,
-                            ThenElseArgs { declare_let_bindings: true, ..args },
+                            ThenElseArgs {
+                                declare_let_bindings: DeclareLetBindings::LetNotPermitted,
+                                ..args
+                            },
                         )
                     });
                 let rhs_success_block = unpack!(this.then_else_break_inner(
                     failure_block,
                     rhs,
-                    ThenElseArgs { declare_let_bindings: true, ..args },
+                    ThenElseArgs {
+                        declare_let_bindings: DeclareLetBindings::LetNotPermitted,
+                        ..args
+                    },
                 ));
 
                 // Make the LHS and RHS success arms converge to a common block.
@@ -126,7 +175,10 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                         this.then_else_break_inner(
                             block,
                             arg,
-                            ThenElseArgs { declare_let_bindings: true, ..args },
+                            ThenElseArgs {
+                                declare_let_bindings: DeclareLetBindings::LetNotPermitted,
+                                ..args
+                            },
                         )
                     });
                 this.break_for_else(success_block, args.variable_source_info);
@@ -146,6 +198,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 Some(args.variable_source_info.scope),
                 args.variable_source_info.span,
                 args.declare_let_bindings,
+                EmitStorageLive::Yes,
             ),
             _ => {
                 let mut block = block;
@@ -314,13 +367,21 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
 
         let match_start_span = span.shrink_to_lo().to(scrutinee_span);
 
-        let fake_borrow_temps = self.lower_match_tree(
+        // The set of places that we are creating fake borrows of. If there are no match guards then
+        // we don't need any fake borrows, so don't track them.
+        let fake_borrow_temps: Vec<(Place<'tcx>, Local, FakeBorrowKind)> = if match_has_guard {
+            util::collect_fake_borrows(self, &candidates, scrutinee_span, scrutinee_place.base())
+        } else {
+            Vec::new()
+        };
+
+        self.lower_match_tree(
             block,
             scrutinee_span,
             &scrutinee_place,
             match_start_span,
-            match_has_guard,
             &mut candidates,
+            false,
         );
 
         self.lower_match_arms(
@@ -375,89 +436,6 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             .collect()
     }
 
-    /// Create the decision tree for the match expression, starting from `block`.
-    ///
-    /// Modifies `candidates` to store the bindings and type ascriptions for
-    /// that candidate.
-    ///
-    /// Returns the places that need fake borrows because we bind or test them.
-    fn lower_match_tree<'pat>(
-        &mut self,
-        block: BasicBlock,
-        scrutinee_span: Span,
-        scrutinee_place_builder: &PlaceBuilder<'tcx>,
-        match_start_span: Span,
-        match_has_guard: bool,
-        candidates: &mut [&mut Candidate<'pat, 'tcx>],
-    ) -> Vec<(Place<'tcx>, Local, FakeBorrowKind)> {
-        // The set of places that we are creating fake borrows of. If there are no match guards then
-        // we don't need any fake borrows, so don't track them.
-        let fake_borrows: Vec<(Place<'tcx>, Local, FakeBorrowKind)> = if match_has_guard {
-            util::collect_fake_borrows(
-                self,
-                candidates,
-                scrutinee_span,
-                scrutinee_place_builder.base(),
-            )
-        } else {
-            Vec::new()
-        };
-
-        // See the doc comment on `match_candidates` for why we have an
-        // otherwise block. Match checking will ensure this is actually
-        // unreachable.
-        let otherwise_block = self.cfg.start_new_block();
-
-        // This will generate code to test scrutinee_place and
-        // branch to the appropriate arm block
-        self.match_candidates(match_start_span, scrutinee_span, block, otherwise_block, candidates);
-
-        let source_info = self.source_info(scrutinee_span);
-
-        // Matching on a `scrutinee_place` with an uninhabited type doesn't
-        // generate any memory reads by itself, and so if the place "expression"
-        // contains unsafe operations like raw pointer dereferences or union
-        // field projections, we wouldn't know to require an `unsafe` block
-        // around a `match` equivalent to `std::intrinsics::unreachable()`.
-        // See issue #47412 for this hole being discovered in the wild.
-        //
-        // HACK(eddyb) Work around the above issue by adding a dummy inspection
-        // of `scrutinee_place`, specifically by applying `ReadForMatch`.
-        //
-        // NOTE: ReadForMatch also checks that the scrutinee is initialized.
-        // This is currently needed to not allow matching on an uninitialized,
-        // uninhabited value. If we get never patterns, those will check that
-        // the place is initialized, and so this read would only be used to
-        // check safety.
-        let cause_matched_place = FakeReadCause::ForMatchedPlace(None);
-
-        if let Some(scrutinee_place) = scrutinee_place_builder.try_to_place(self) {
-            self.cfg.push_fake_read(
-                otherwise_block,
-                source_info,
-                cause_matched_place,
-                scrutinee_place,
-            );
-        }
-
-        self.cfg.terminate(otherwise_block, source_info, TerminatorKind::Unreachable);
-
-        // Link each leaf candidate to the `pre_binding_block` of the next one.
-        let mut previous_candidate: Option<&mut Candidate<'_, '_>> = None;
-
-        for candidate in candidates {
-            candidate.visit_leaves(|leaf_candidate| {
-                if let Some(ref mut prev) = previous_candidate {
-                    assert!(leaf_candidate.false_edge_start_block.is_some());
-                    prev.next_candidate_start_block = leaf_candidate.false_edge_start_block;
-                }
-                previous_candidate = Some(leaf_candidate);
-            });
-        }
-
-        fake_borrows
-    }
-
     /// Lower the bindings, guards and arm bodies of a `match` expression.
     ///
     /// The decision tree should have already been created
@@ -513,7 +491,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                         &fake_borrow_temps,
                         scrutinee_span,
                         Some((arm, match_scope)),
-                        false,
+                        EmitStorageLive::Yes,
                     );
 
                     this.fixed_temps_scope = old_dedup_scope;
@@ -558,7 +536,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         fake_borrow_temps: &[(Place<'tcx>, Local, FakeBorrowKind)],
         scrutinee_span: Span,
         arm_match_scope: Option<(&Arm<'tcx>, region::Scope)>,
-        storages_alive: bool,
+        emit_storage_live: EmitStorageLive,
     ) -> BasicBlock {
         if candidate.subcandidates.is_empty() {
             // Avoid generating another `BasicBlock` when we only have one
@@ -569,8 +547,8 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 fake_borrow_temps,
                 scrutinee_span,
                 arm_match_scope,
-                true,
-                storages_alive,
+                ScheduleDrops::Yes,
+                emit_storage_live,
             )
         } else {
             // It's helpful to avoid scheduling drops multiple times to save
@@ -588,7 +566,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             // To handle this we instead unschedule it's drop after each time
             // we lower the guard.
             let target_block = self.cfg.start_new_block();
-            let mut schedule_drops = true;
+            let mut schedule_drops = ScheduleDrops::Yes;
             let arm = arm_match_scope.unzip().0;
             // We keep a stack of all of the bindings and type ascriptions
             // from the parent candidates that we visit, that also need to
@@ -607,10 +585,10 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                         scrutinee_span,
                         arm_match_scope,
                         schedule_drops,
-                        storages_alive,
+                        emit_storage_live,
                     );
                     if arm.is_none() {
-                        schedule_drops = false;
+                        schedule_drops = ScheduleDrops::No;
                     }
                     self.cfg.goto(binding_end, outer_source_info, target_block);
                 },
@@ -636,8 +614,13 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         match irrefutable_pat.kind {
             // Optimize the case of `let x = ...` to write directly into `x`
             PatKind::Binding { mode: BindingMode(ByRef::No, _), var, subpattern: None, .. } => {
-                let place =
-                    self.storage_live_binding(block, var, irrefutable_pat.span, OutsideGuard, true);
+                let place = self.storage_live_binding(
+                    block,
+                    var,
+                    irrefutable_pat.span,
+                    OutsideGuard,
+                    ScheduleDrops::Yes,
+                );
                 unpack!(block = self.expr_into_dest(place, block, initializer_id));
 
                 // Inject a fake read, see comments on `FakeReadCause::ForLet`.
@@ -670,8 +653,13 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                     },
                 ascription: thir::Ascription { ref annotation, variance: _ },
             } => {
-                let place =
-                    self.storage_live_binding(block, var, irrefutable_pat.span, OutsideGuard, true);
+                let place = self.storage_live_binding(
+                    block,
+                    var,
+                    irrefutable_pat.span,
+                    OutsideGuard,
+                    ScheduleDrops::Yes,
+                );
                 unpack!(block = self.expr_into_dest(place, block, initializer_id));
 
                 // Inject a fake read, see comments on `FakeReadCause::ForLet`.
@@ -728,62 +716,56 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         set_match_place: bool,
     ) -> BlockAnd<()> {
         let mut candidate = Candidate::new(initializer.clone(), irrefutable_pat, false, self);
-        let fake_borrow_temps = self.lower_match_tree(
-            block,
-            irrefutable_pat.span,
-            &initializer,
-            irrefutable_pat.span,
-            false,
-            &mut [&mut candidate],
-        );
 
         // For matches and function arguments, the place that is being matched
         // can be set when creating the variables. But the place for
         // let PATTERN = ... might not even exist until we do the assignment.
         // so we set it here instead.
         if set_match_place {
-            let mut next = Some(&candidate);
-            while let Some(candidate_ref) = next.take() {
-                for binding in &candidate_ref.extra_data.bindings {
+            // `try_to_place` may fail if it is unable to resolve the given `PlaceBuilder` inside a
+            // closure. In this case, we don't want to include a scrutinee place.
+            // `scrutinee_place_builder` will fail for destructured assignments. This is because a
+            // closure only captures the precise places that it will read and as a result a closure
+            // may not capture the entire tuple/struct and rather have individual places that will
+            // be read in the final MIR.
+            // Example:
+            // ```
+            // let foo = (0, 1);
+            // let c = || {
+            //    let (v1, v2) = foo;
+            // };
+            // ```
+            if let Some(place) = initializer.try_to_place(self) {
+                visit_bindings(&[&mut candidate], |binding: &Binding<'_>| {
                     let local = self.var_local_id(binding.var_id, OutsideGuard);
-                    // `try_to_place` may fail if it is unable to resolve the given
-                    // `PlaceBuilder` inside a closure. In this case, we don't want to include
-                    // a scrutinee place. `scrutinee_place_builder` will fail for destructured
-                    // assignments. This is because a closure only captures the precise places
-                    // that it will read and as a result a closure may not capture the entire
-                    // tuple/struct and rather have individual places that will be read in the
-                    // final MIR.
-                    // Example:
-                    // ```
-                    // let foo = (0, 1);
-                    // let c = || {
-                    //    let (v1, v2) = foo;
-                    // };
-                    // ```
-                    if let Some(place) = initializer.try_to_place(self) {
-                        let LocalInfo::User(BindingForm::Var(VarBindingForm {
-                            opt_match_place: Some((ref mut match_place, _)),
-                            ..
-                        })) = **self.local_decls[local].local_info.as_mut().assert_crate_local()
-                        else {
-                            bug!("Let binding to non-user variable.")
-                        };
+                    if let LocalInfo::User(BindingForm::Var(VarBindingForm {
+                        opt_match_place: Some((ref mut match_place, _)),
+                        ..
+                    })) = **self.local_decls[local].local_info.as_mut().assert_crate_local()
+                    {
                         *match_place = Some(place);
-                    }
-                }
-                // All of the subcandidates should bind the same locals, so we
-                // only visit the first one.
-                next = candidate_ref.subcandidates.get(0)
+                    } else {
+                        bug!("Let binding to non-user variable.")
+                    };
+                });
             }
         }
 
+        self.lower_match_tree(
+            block,
+            irrefutable_pat.span,
+            &initializer,
+            irrefutable_pat.span,
+            &mut [&mut candidate],
+            false,
+        );
         self.bind_pattern(
             self.source_info(irrefutable_pat.span),
             candidate,
-            fake_borrow_temps.as_slice(),
+            &[],
             irrefutable_pat.span,
             None,
-            false,
+            EmitStorageLive::Yes,
         )
         .unit()
     }
@@ -859,13 +841,15 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         }
     }
 
+    /// Emits a [`StatementKind::StorageLive`] for the given var, and also
+    /// schedules a drop if requested (and possible).
     pub(crate) fn storage_live_binding(
         &mut self,
         block: BasicBlock,
         var: LocalVarId,
         span: Span,
         for_guard: ForGuard,
-        schedule_drop: bool,
+        schedule_drop: ScheduleDrops,
     ) -> Place<'tcx> {
         let local_id = self.var_local_id(var, for_guard);
         let source_info = self.source_info(span);
@@ -873,7 +857,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         // Although there is almost always scope for given variable in corner cases
         // like #92893 we might get variable with no scope.
         if let Some(region_scope) = self.region_scope_tree.var_scope(var.0.local_id)
-            && schedule_drop
+            && matches!(schedule_drop, ScheduleDrops::Yes)
         {
             self.schedule_drop(span, region_scope, local_id, DropKind::Storage);
         }
@@ -1306,6 +1290,79 @@ pub(crate) struct ArmHasGuard(pub(crate) bool);
 // Main matching algorithm
 
 impl<'a, 'tcx> Builder<'a, 'tcx> {
+    /// The entrypoint of the matching algorithm. Create the decision tree for the match expression,
+    /// starting from `block`.
+    ///
+    /// Modifies `candidates` to store the bindings and type ascriptions for
+    /// that candidate.
+    ///
+    /// `refutable` indicates whether the candidate list is refutable (for `if let` and `let else`)
+    /// or not (for `let` and `match`). In the refutable case we return the block to which we branch
+    /// on failure.
+    fn lower_match_tree<'pat>(
+        &mut self,
+        block: BasicBlock,
+        scrutinee_span: Span,
+        scrutinee_place_builder: &PlaceBuilder<'tcx>,
+        match_start_span: Span,
+        candidates: &mut [&mut Candidate<'pat, 'tcx>],
+        refutable: bool,
+    ) -> BasicBlock {
+        // See the doc comment on `match_candidates` for why we have an otherwise block.
+        let otherwise_block = self.cfg.start_new_block();
+
+        // This will generate code to test scrutinee_place and branch to the appropriate arm block
+        self.match_candidates(match_start_span, scrutinee_span, block, otherwise_block, candidates);
+
+        // Link each leaf candidate to the `false_edge_start_block` of the next one.
+        let mut previous_candidate: Option<&mut Candidate<'_, '_>> = None;
+        for candidate in candidates {
+            candidate.visit_leaves(|leaf_candidate| {
+                if let Some(ref mut prev) = previous_candidate {
+                    assert!(leaf_candidate.false_edge_start_block.is_some());
+                    prev.next_candidate_start_block = leaf_candidate.false_edge_start_block;
+                }
+                previous_candidate = Some(leaf_candidate);
+            });
+        }
+
+        if refutable {
+            // In refutable cases there's always at least one candidate, and we want a false edge to
+            // the failure block.
+            previous_candidate.as_mut().unwrap().next_candidate_start_block = Some(otherwise_block)
+        } else {
+            // Match checking ensures `otherwise_block` is actually unreachable in irrefutable
+            // cases.
+            let source_info = self.source_info(scrutinee_span);
+
+            // Matching on a scrutinee place of an uninhabited type doesn't generate any memory
+            // reads by itself, and so if the place is uninitialized we wouldn't know. In order to
+            // disallow the following:
+            // ```rust
+            // let x: !;
+            // match x {}
+            // ```
+            // we add a dummy read on the place.
+            //
+            // NOTE: If we require never patterns for empty matches, those will check that the place
+            // is initialized, and so this read would no longer be needed.
+            let cause_matched_place = FakeReadCause::ForMatchedPlace(None);
+
+            if let Some(scrutinee_place) = scrutinee_place_builder.try_to_place(self) {
+                self.cfg.push_fake_read(
+                    otherwise_block,
+                    source_info,
+                    cause_matched_place,
+                    scrutinee_place,
+                );
+            }
+
+            self.cfg.terminate(otherwise_block, source_info, TerminatorKind::Unreachable);
+        }
+
+        otherwise_block
+    }
+
     /// The main match algorithm. It begins with a set of candidates
     /// `candidates` and has the job of generating code to determine
     /// which of these candidates, if any, is the correct one. The
@@ -1997,53 +2054,69 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
 // Pat binding - used for `let` and function parameters as well.
 
 impl<'a, 'tcx> Builder<'a, 'tcx> {
-    /// If the bindings have already been declared, set `declare_bindings` to
-    /// `false` to avoid duplicated bindings declaration. Used for if-let guards.
+    /// Lowers a `let` expression that appears in a suitable context
+    /// (e.g. an `if` condition or match guard).
+    ///
+    /// Also used for lowering let-else statements, since they have similar
+    /// needs despite not actually using `let` expressions.
+    ///
+    /// Use [`DeclareLetBindings`] to control whether the `let` bindings are
+    /// declared or not.
     pub(crate) fn lower_let_expr(
         &mut self,
         mut block: BasicBlock,
         expr_id: ExprId,
         pat: &Pat<'tcx>,
         source_scope: Option<SourceScope>,
-        span: Span,
-        declare_bindings: bool,
+        scope_span: Span,
+        declare_let_bindings: DeclareLetBindings,
+        emit_storage_live: EmitStorageLive,
     ) -> BlockAnd<()> {
         let expr_span = self.thir[expr_id].span;
-        let expr_place_builder = unpack!(block = self.lower_scrutinee(block, expr_id, expr_span));
-        let wildcard = Pat::wildcard_from_ty(pat.ty);
-        let mut guard_candidate = Candidate::new(expr_place_builder.clone(), pat, false, self);
-        let mut otherwise_candidate =
-            Candidate::new(expr_place_builder.clone(), &wildcard, false, self);
-        let fake_borrow_temps = self.lower_match_tree(
+        let scrutinee = unpack!(block = self.lower_scrutinee(block, expr_id, expr_span));
+        let mut candidate = Candidate::new(scrutinee.clone(), pat, false, self);
+        let otherwise_block = self.lower_match_tree(
             block,
+            expr_span,
+            &scrutinee,
             pat.span,
-            &expr_place_builder,
-            pat.span,
-            false,
-            &mut [&mut guard_candidate, &mut otherwise_candidate],
+            &mut [&mut candidate],
+            true,
         );
-        let expr_place = expr_place_builder.try_to_place(self);
-        let opt_expr_place = expr_place.as_ref().map(|place| (Some(place), expr_span));
-        let otherwise_post_guard_block = otherwise_candidate.pre_binding_block.unwrap();
-        self.break_for_else(otherwise_post_guard_block, self.source_info(expr_span));
 
-        if declare_bindings {
-            self.declare_bindings(source_scope, pat.span.to(span), pat, None, opt_expr_place);
+        self.break_for_else(otherwise_block, self.source_info(expr_span));
+
+        match declare_let_bindings {
+            DeclareLetBindings::Yes => {
+                let expr_place = scrutinee.try_to_place(self);
+                let opt_expr_place = expr_place.as_ref().map(|place| (Some(place), expr_span));
+                self.declare_bindings(
+                    source_scope,
+                    pat.span.to(scope_span),
+                    pat,
+                    None,
+                    opt_expr_place,
+                );
+            }
+            DeclareLetBindings::No => {} // Caller is responsible for bindings.
+            DeclareLetBindings::LetNotPermitted => {
+                self.tcx.dcx().span_bug(expr_span, "let expression not expected in this context")
+            }
         }
 
-        let post_guard_block = self.bind_pattern(
+        let success = self.bind_pattern(
             self.source_info(pat.span),
-            guard_candidate,
-            fake_borrow_temps.as_slice(),
+            candidate,
+            &[],
             expr_span,
             None,
-            false,
+            emit_storage_live,
         );
 
         // If branch coverage is enabled, record this branch.
-        self.visit_coverage_conditional_let(pat, post_guard_block, otherwise_post_guard_block);
+        self.visit_coverage_conditional_let(pat, success, otherwise_block);
 
-        post_guard_block.unit()
+        success.unit()
     }
 
     /// Initializes each of the bindings from the candidate by
@@ -2061,8 +2134,8 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         fake_borrows: &[(Place<'tcx>, Local, FakeBorrowKind)],
         scrutinee_span: Span,
         arm_match_scope: Option<(&Arm<'tcx>, region::Scope)>,
-        schedule_drops: bool,
-        storages_alive: bool,
+        schedule_drops: ScheduleDrops,
+        emit_storage_live: EmitStorageLive,
     ) -> BasicBlock {
         debug!("bind_and_guard_matched_candidate(candidate={:?})", candidate);
 
@@ -2091,14 +2164,15 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             return self.cfg.start_new_block();
         }
 
-        self.ascribe_types(
-            block,
-            parent_data
-                .iter()
-                .flat_map(|d| &d.ascriptions)
-                .cloned()
-                .chain(candidate.extra_data.ascriptions),
-        );
+        let ascriptions = parent_data
+            .iter()
+            .flat_map(|d| &d.ascriptions)
+            .cloned()
+            .chain(candidate.extra_data.ascriptions);
+        let bindings =
+            parent_data.iter().flat_map(|d| &d.bindings).chain(&candidate.extra_data.bindings);
+
+        self.ascribe_types(block, ascriptions);
 
         // rust-lang/rust#27282: The `autoref` business deserves some
         // explanation here.
@@ -2185,12 +2259,11 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             && let Some(guard) = arm.guard
         {
             let tcx = self.tcx;
-            let bindings =
-                parent_data.iter().flat_map(|d| &d.bindings).chain(&candidate.extra_data.bindings);
 
             self.bind_matched_candidate_for_guard(block, schedule_drops, bindings.clone());
-            let guard_frame =
-                GuardFrame { locals: bindings.map(|b| GuardFrameLocal::new(b.var_id)).collect() };
+            let guard_frame = GuardFrame {
+                locals: bindings.clone().map(|b| GuardFrameLocal::new(b.var_id)).collect(),
+            };
             debug!("entering guard building context: {:?}", guard_frame);
             self.guard_context.push(guard_frame);
 
@@ -2211,7 +2284,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                         guard,
                         None, // Use `self.local_scope()` as the temp scope
                         this.source_info(arm.span),
-                        false, // For guards, `let` bindings are declared separately
+                        DeclareLetBindings::No, // For guards, `let` bindings are declared separately
                     )
                 });
 
@@ -2263,11 +2336,8 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             // ```
             //
             // and that is clearly not correct.
-            let by_value_bindings = parent_data
-                .iter()
-                .flat_map(|d| &d.bindings)
-                .chain(&candidate.extra_data.bindings)
-                .filter(|binding| matches!(binding.binding_mode.0, ByRef::No));
+            let by_value_bindings =
+                bindings.filter(|binding| matches!(binding.binding_mode.0, ByRef::No));
             // Read all of the by reference bindings to ensure that the
             // place they refer to can't be modified by the guard.
             for binding in by_value_bindings.clone() {
@@ -2275,12 +2345,16 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 let cause = FakeReadCause::ForGuardBinding;
                 self.cfg.push_fake_read(post_guard_block, guard_end, cause, Place::from(local_id));
             }
-            assert!(schedule_drops, "patterns with guards must schedule drops");
+            assert_matches!(
+                schedule_drops,
+                ScheduleDrops::Yes,
+                "patterns with guards must schedule drops"
+            );
             self.bind_matched_candidate_for_arm_body(
                 post_guard_block,
-                true,
+                ScheduleDrops::Yes,
                 by_value_bindings,
-                storages_alive,
+                emit_storage_live,
             );
 
             post_guard_block
@@ -2291,8 +2365,8 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             self.bind_matched_candidate_for_arm_body(
                 block,
                 schedule_drops,
-                parent_data.iter().flat_map(|d| &d.bindings).chain(&candidate.extra_data.bindings),
-                storages_alive,
+                bindings,
+                emit_storage_live,
             );
             block
         }
@@ -2328,7 +2402,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
     fn bind_matched_candidate_for_guard<'b>(
         &mut self,
         block: BasicBlock,
-        schedule_drops: bool,
+        schedule_drops: ScheduleDrops,
         bindings: impl IntoIterator<Item = &'b Binding<'tcx>>,
     ) where
         'tcx: 'b,
@@ -2381,9 +2455,9 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
     fn bind_matched_candidate_for_arm_body<'b>(
         &mut self,
         block: BasicBlock,
-        schedule_drops: bool,
+        schedule_drops: ScheduleDrops,
         bindings: impl IntoIterator<Item = &'b Binding<'tcx>>,
-        storages_alive: bool,
+        emit_storage_live: EmitStorageLive,
     ) where
         'tcx: 'b,
     {
@@ -2393,21 +2467,20 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         // Assign each of the bindings. This may trigger moves out of the candidate.
         for binding in bindings {
             let source_info = self.source_info(binding.span);
-            let local = if storages_alive {
+            let local = match emit_storage_live {
                 // Here storages are already alive, probably because this is a binding
                 // from let-else.
                 // We just need to schedule drop for the value.
-                self.var_local_id(binding.var_id, OutsideGuard).into()
-            } else {
-                self.storage_live_binding(
+                EmitStorageLive::No => self.var_local_id(binding.var_id, OutsideGuard).into(),
+                EmitStorageLive::Yes => self.storage_live_binding(
                     block,
                     binding.var_id,
                     binding.span,
                     OutsideGuard,
                     schedule_drops,
-                )
+                ),
             };
-            if schedule_drops {
+            if matches!(schedule_drops, ScheduleDrops::Yes) {
                 self.schedule_drop_for_binding(binding.var_id, binding.span, OutsideGuard);
             }
             let rvalue = match binding.binding_mode.0 {
@@ -2493,55 +2566,4 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         debug!(?locals);
         self.var_indices.insert(var_id, locals);
     }
-
-    pub(crate) fn ast_let_else(
-        &mut self,
-        mut block: BasicBlock,
-        init_id: ExprId,
-        initializer_span: Span,
-        else_block: BlockId,
-        let_else_scope: &region::Scope,
-        pattern: &Pat<'tcx>,
-    ) -> BlockAnd<BasicBlock> {
-        let else_block_span = self.thir[else_block].span;
-        let (matching, failure) = self.in_if_then_scope(*let_else_scope, else_block_span, |this| {
-            let scrutinee = unpack!(block = this.lower_scrutinee(block, init_id, initializer_span));
-            let pat = Pat { ty: pattern.ty, span: else_block_span, kind: PatKind::Wild };
-            let mut wildcard = Candidate::new(scrutinee.clone(), &pat, false, this);
-            let mut candidate = Candidate::new(scrutinee.clone(), pattern, false, this);
-            let fake_borrow_temps = this.lower_match_tree(
-                block,
-                initializer_span,
-                &scrutinee,
-                pattern.span,
-                false,
-                &mut [&mut candidate, &mut wildcard],
-            );
-            // This block is for the matching case
-            let matching = this.bind_pattern(
-                this.source_info(pattern.span),
-                candidate,
-                fake_borrow_temps.as_slice(),
-                initializer_span,
-                None,
-                true,
-            );
-            // This block is for the failure case
-            let failure = this.bind_pattern(
-                this.source_info(else_block_span),
-                wildcard,
-                fake_borrow_temps.as_slice(),
-                initializer_span,
-                None,
-                true,
-            );
-
-            // If branch coverage is enabled, record this branch.
-            this.visit_coverage_conditional_let(pattern, matching, failure);
-
-            this.break_for_else(failure, this.source_info(initializer_span));
-            matching.unit()
-        });
-        matching.and(failure)
-    }
 }
diff --git a/compiler/rustc_mir_build/src/build/matches/util.rs b/compiler/rustc_mir_build/src/build/matches/util.rs
index 630d0b9438d..3bec154e1df 100644
--- a/compiler/rustc_mir_build/src/build/matches/util.rs
+++ b/compiler/rustc_mir_build/src/build/matches/util.rs
@@ -1,3 +1,5 @@
+use std::marker::PhantomData;
+
 use crate::build::expr::as_place::{PlaceBase, PlaceBuilder};
 use crate::build::matches::{Binding, Candidate, FlatPat, MatchPair, TestCase};
 use crate::build::Builder;
@@ -269,18 +271,6 @@ impl<'pat, 'tcx> MatchPair<'pat, 'tcx> {
     }
 }
 
-pub(super) struct FakeBorrowCollector<'a, 'b, 'tcx> {
-    cx: &'a mut Builder<'b, 'tcx>,
-    /// Base of the scrutinee place. Used to distinguish bindings inside the scrutinee place from
-    /// bindings inside deref patterns.
-    scrutinee_base: PlaceBase,
-    /// Store for each place the kind of borrow to take. In case of conflicts, we take the strongest
-    /// borrow (i.e. Deep > Shallow).
-    /// Invariant: for any place in `fake_borrows`, all the prefixes of this place that are
-    /// dereferences are also borrowed with the same of stronger borrow kind.
-    fake_borrows: FxIndexMap<Place<'tcx>, FakeBorrowKind>,
-}
-
 /// Determine the set of places that have to be stable across match guards.
 ///
 /// Returns a list of places that need a fake borrow along with a local to store it.
@@ -344,6 +334,18 @@ pub(super) fn collect_fake_borrows<'tcx>(
         .collect()
 }
 
+pub(super) struct FakeBorrowCollector<'a, 'b, 'tcx> {
+    cx: &'a mut Builder<'b, 'tcx>,
+    /// Base of the scrutinee place. Used to distinguish bindings inside the scrutinee place from
+    /// bindings inside deref patterns.
+    scrutinee_base: PlaceBase,
+    /// Store for each place the kind of borrow to take. In case of conflicts, we take the strongest
+    /// borrow (i.e. Deep > Shallow).
+    /// Invariant: for any place in `fake_borrows`, all the prefixes of this place that are
+    /// dereferences are also borrowed with the same of stronger borrow kind.
+    fake_borrows: FxIndexMap<Place<'tcx>, FakeBorrowKind>,
+}
+
 impl<'a, 'b, 'tcx> FakeBorrowCollector<'a, 'b, 'tcx> {
     // Fake borrow this place and its dereference prefixes.
     fn fake_borrow(&mut self, place: Place<'tcx>, kind: FakeBorrowKind) {
@@ -457,6 +459,57 @@ impl<'a, 'b, 'tcx> FakeBorrowCollector<'a, 'b, 'tcx> {
     }
 }
 
+/// Visit all the bindings of these candidates. Because or-alternatives bind the same variables, we
+/// only explore the first one of each or-pattern.
+pub(super) fn visit_bindings<'tcx>(
+    candidates: &[&mut Candidate<'_, 'tcx>],
+    f: impl FnMut(&Binding<'tcx>),
+) {
+    let mut visitor = BindingsVisitor { f, phantom: PhantomData };
+    for candidate in candidates.iter() {
+        visitor.visit_candidate(candidate);
+    }
+}
+
+pub(super) struct BindingsVisitor<'tcx, F> {
+    f: F,
+    phantom: PhantomData<&'tcx ()>,
+}
+
+impl<'tcx, F> BindingsVisitor<'tcx, F>
+where
+    F: FnMut(&Binding<'tcx>),
+{
+    fn visit_candidate(&mut self, candidate: &Candidate<'_, 'tcx>) {
+        for binding in &candidate.extra_data.bindings {
+            (self.f)(binding)
+        }
+        for match_pair in &candidate.match_pairs {
+            self.visit_match_pair(match_pair);
+        }
+    }
+
+    fn visit_flat_pat(&mut self, flat_pat: &FlatPat<'_, 'tcx>) {
+        for binding in &flat_pat.extra_data.bindings {
+            (self.f)(binding)
+        }
+        for match_pair in &flat_pat.match_pairs {
+            self.visit_match_pair(match_pair);
+        }
+    }
+
+    fn visit_match_pair(&mut self, match_pair: &MatchPair<'_, 'tcx>) {
+        if let TestCase::Or { pats, .. } = &match_pair.test_case {
+            // All the or-alternatives should bind the same locals, so we only visit the first one.
+            self.visit_flat_pat(&pats[0])
+        } else {
+            for subpair in &match_pair.subpairs {
+                self.visit_match_pair(subpair);
+            }
+        }
+    }
+}
+
 #[must_use]
 pub(crate) fn ref_pat_borrow_kind(ref_mutability: Mutability) -> BorrowKind {
     match ref_mutability {
diff --git a/compiler/rustc_mir_dataflow/src/impls/initialized.rs b/compiler/rustc_mir_dataflow/src/impls/initialized.rs
index f0b79dab0c9..ffcf630b653 100644
--- a/compiler/rustc_mir_dataflow/src/impls/initialized.rs
+++ b/compiler/rustc_mir_dataflow/src/impls/initialized.rs
@@ -50,15 +50,19 @@ use crate::{lattice, AnalysisDomain, GenKill, GenKillAnalysis, MaybeReachable};
 /// Similarly, at a given `drop` statement, the set-intersection
 /// between this data and `MaybeUninitializedPlaces` yields the set of
 /// places that would require a dynamic drop-flag at that statement.
-pub struct MaybeInitializedPlaces<'a, 'tcx> {
+pub struct MaybeInitializedPlaces<'a, 'mir, 'tcx> {
     tcx: TyCtxt<'tcx>,
-    body: &'a Body<'tcx>,
+    body: &'mir Body<'tcx>,
     mdpe: &'a MoveDataParamEnv<'tcx>,
     skip_unreachable_unwind: bool,
 }
 
-impl<'a, 'tcx> MaybeInitializedPlaces<'a, 'tcx> {
-    pub fn new(tcx: TyCtxt<'tcx>, body: &'a Body<'tcx>, mdpe: &'a MoveDataParamEnv<'tcx>) -> Self {
+impl<'a, 'mir, 'tcx> MaybeInitializedPlaces<'a, 'mir, 'tcx> {
+    pub fn new(
+        tcx: TyCtxt<'tcx>,
+        body: &'mir Body<'tcx>,
+        mdpe: &'a MoveDataParamEnv<'tcx>,
+    ) -> Self {
         MaybeInitializedPlaces { tcx, body, mdpe, skip_unreachable_unwind: false }
     }
 
@@ -84,7 +88,7 @@ impl<'a, 'tcx> MaybeInitializedPlaces<'a, 'tcx> {
     }
 }
 
-impl<'a, 'tcx> HasMoveData<'tcx> for MaybeInitializedPlaces<'a, 'tcx> {
+impl<'a, 'mir, 'tcx> HasMoveData<'tcx> for MaybeInitializedPlaces<'a, 'mir, 'tcx> {
     fn move_data(&self) -> &MoveData<'tcx> {
         &self.mdpe.move_data
     }
@@ -125,17 +129,21 @@ impl<'a, 'tcx> HasMoveData<'tcx> for MaybeInitializedPlaces<'a, 'tcx> {
 /// Similarly, at a given `drop` statement, the set-intersection
 /// between this data and `MaybeInitializedPlaces` yields the set of
 /// places that would require a dynamic drop-flag at that statement.
-pub struct MaybeUninitializedPlaces<'a, 'tcx> {
+pub struct MaybeUninitializedPlaces<'a, 'mir, 'tcx> {
     tcx: TyCtxt<'tcx>,
-    body: &'a Body<'tcx>,
+    body: &'mir Body<'tcx>,
     mdpe: &'a MoveDataParamEnv<'tcx>,
 
     mark_inactive_variants_as_uninit: bool,
     skip_unreachable_unwind: BitSet<mir::BasicBlock>,
 }
 
-impl<'a, 'tcx> MaybeUninitializedPlaces<'a, 'tcx> {
-    pub fn new(tcx: TyCtxt<'tcx>, body: &'a Body<'tcx>, mdpe: &'a MoveDataParamEnv<'tcx>) -> Self {
+impl<'a, 'mir, 'tcx> MaybeUninitializedPlaces<'a, 'mir, 'tcx> {
+    pub fn new(
+        tcx: TyCtxt<'tcx>,
+        body: &'mir Body<'tcx>,
+        mdpe: &'a MoveDataParamEnv<'tcx>,
+    ) -> Self {
         MaybeUninitializedPlaces {
             tcx,
             body,
@@ -164,7 +172,7 @@ impl<'a, 'tcx> MaybeUninitializedPlaces<'a, 'tcx> {
     }
 }
 
-impl<'a, 'tcx> HasMoveData<'tcx> for MaybeUninitializedPlaces<'a, 'tcx> {
+impl<'a, 'tcx> HasMoveData<'tcx> for MaybeUninitializedPlaces<'a, '_, 'tcx> {
     fn move_data(&self) -> &MoveData<'tcx> {
         &self.mdpe.move_data
     }
@@ -250,24 +258,24 @@ impl<'a, 'tcx> HasMoveData<'tcx> for DefinitelyInitializedPlaces<'a, 'tcx> {
 ///     c = S;                                  // {a, b, c, d }
 /// }
 /// ```
-pub struct EverInitializedPlaces<'a, 'tcx> {
-    body: &'a Body<'tcx>,
+pub struct EverInitializedPlaces<'a, 'mir, 'tcx> {
+    body: &'mir Body<'tcx>,
     mdpe: &'a MoveDataParamEnv<'tcx>,
 }
 
-impl<'a, 'tcx> EverInitializedPlaces<'a, 'tcx> {
-    pub fn new(body: &'a Body<'tcx>, mdpe: &'a MoveDataParamEnv<'tcx>) -> Self {
+impl<'a, 'mir, 'tcx> EverInitializedPlaces<'a, 'mir, 'tcx> {
+    pub fn new(body: &'mir Body<'tcx>, mdpe: &'a MoveDataParamEnv<'tcx>) -> Self {
         EverInitializedPlaces { body, mdpe }
     }
 }
 
-impl<'a, 'tcx> HasMoveData<'tcx> for EverInitializedPlaces<'a, 'tcx> {
+impl<'a, 'tcx> HasMoveData<'tcx> for EverInitializedPlaces<'a, '_, 'tcx> {
     fn move_data(&self) -> &MoveData<'tcx> {
         &self.mdpe.move_data
     }
 }
 
-impl<'a, 'tcx> MaybeInitializedPlaces<'a, 'tcx> {
+impl<'a, 'mir, 'tcx> MaybeInitializedPlaces<'a, 'mir, 'tcx> {
     fn update_bits(
         trans: &mut impl GenKill<MovePathIndex>,
         path: MovePathIndex,
@@ -280,7 +288,7 @@ impl<'a, 'tcx> MaybeInitializedPlaces<'a, 'tcx> {
     }
 }
 
-impl<'a, 'tcx> MaybeUninitializedPlaces<'a, 'tcx> {
+impl<'a, 'tcx> MaybeUninitializedPlaces<'a, '_, 'tcx> {
     fn update_bits(
         trans: &mut impl GenKill<MovePathIndex>,
         path: MovePathIndex,
@@ -306,7 +314,7 @@ impl<'a, 'tcx> DefinitelyInitializedPlaces<'a, 'tcx> {
     }
 }
 
-impl<'tcx> AnalysisDomain<'tcx> for MaybeInitializedPlaces<'_, 'tcx> {
+impl<'tcx> AnalysisDomain<'tcx> for MaybeInitializedPlaces<'_, '_, 'tcx> {
     /// There can be many more `MovePathIndex` than there are locals in a MIR body.
     /// We use a chunked bitset to avoid paying too high a memory footprint.
     type Domain = MaybeReachable<ChunkedBitSet<MovePathIndex>>;
@@ -328,7 +336,7 @@ impl<'tcx> AnalysisDomain<'tcx> for MaybeInitializedPlaces<'_, 'tcx> {
     }
 }
 
-impl<'tcx> GenKillAnalysis<'tcx> for MaybeInitializedPlaces<'_, 'tcx> {
+impl<'tcx> GenKillAnalysis<'tcx> for MaybeInitializedPlaces<'_, '_, 'tcx> {
     type Idx = MovePathIndex;
 
     fn domain_size(&self, _: &Body<'tcx>) -> usize {
@@ -441,7 +449,7 @@ impl<'tcx> GenKillAnalysis<'tcx> for MaybeInitializedPlaces<'_, 'tcx> {
     }
 }
 
-impl<'tcx> AnalysisDomain<'tcx> for MaybeUninitializedPlaces<'_, 'tcx> {
+impl<'tcx> AnalysisDomain<'tcx> for MaybeUninitializedPlaces<'_, '_, 'tcx> {
     /// There can be many more `MovePathIndex` than there are locals in a MIR body.
     /// We use a chunked bitset to avoid paying too high a memory footprint.
     type Domain = ChunkedBitSet<MovePathIndex>;
@@ -465,7 +473,7 @@ impl<'tcx> AnalysisDomain<'tcx> for MaybeUninitializedPlaces<'_, 'tcx> {
     }
 }
 
-impl<'tcx> GenKillAnalysis<'tcx> for MaybeUninitializedPlaces<'_, 'tcx> {
+impl<'tcx> GenKillAnalysis<'tcx> for MaybeUninitializedPlaces<'_, '_, 'tcx> {
     type Idx = MovePathIndex;
 
     fn domain_size(&self, _: &Body<'tcx>) -> usize {
@@ -642,7 +650,7 @@ impl<'tcx> GenKillAnalysis<'tcx> for DefinitelyInitializedPlaces<'_, 'tcx> {
     }
 }
 
-impl<'tcx> AnalysisDomain<'tcx> for EverInitializedPlaces<'_, 'tcx> {
+impl<'tcx> AnalysisDomain<'tcx> for EverInitializedPlaces<'_, '_, 'tcx> {
     /// There can be many more `InitIndex` than there are locals in a MIR body.
     /// We use a chunked bitset to avoid paying too high a memory footprint.
     type Domain = ChunkedBitSet<InitIndex>;
@@ -661,7 +669,7 @@ impl<'tcx> AnalysisDomain<'tcx> for EverInitializedPlaces<'_, 'tcx> {
     }
 }
 
-impl<'tcx> GenKillAnalysis<'tcx> for EverInitializedPlaces<'_, 'tcx> {
+impl<'tcx> GenKillAnalysis<'tcx> for EverInitializedPlaces<'_, '_, 'tcx> {
     type Idx = InitIndex;
 
     fn domain_size(&self, _: &Body<'tcx>) -> usize {
diff --git a/compiler/rustc_mir_dataflow/src/value_analysis.rs b/compiler/rustc_mir_dataflow/src/value_analysis.rs
index 5e2d88f94ca..bfbfff7e259 100644
--- a/compiler/rustc_mir_dataflow/src/value_analysis.rs
+++ b/compiler/rustc_mir_dataflow/src/value_analysis.rs
@@ -846,9 +846,10 @@ impl Map {
 
         if let ty::Ref(_, ref_ty, _) | ty::RawPtr(ref_ty, _) = ty.kind()
             && let ty::Slice(..) = ref_ty.kind()
+            // The user may have written a predicate like `[T]: Sized` in their where clauses,
+            // which makes slices scalars.
+            && self.places[place].value_index.is_none()
         {
-            assert!(self.places[place].value_index.is_none(), "slices are not scalars");
-
             // Prepend new child to the linked list.
             let len = self.places.push(PlaceInfo::new(Some(TrackElem::DerefLen)));
             self.places[len].next_sibling = self.places[place].first_child;
diff --git a/compiler/rustc_mir_transform/src/cost_checker.rs b/compiler/rustc_mir_transform/src/cost_checker.rs
index 7e401b5482f..3333bebff3a 100644
--- a/compiler/rustc_mir_transform/src/cost_checker.rs
+++ b/compiler/rustc_mir_transform/src/cost_checker.rs
@@ -31,6 +31,37 @@ impl<'b, 'tcx> CostChecker<'b, 'tcx> {
         CostChecker { tcx, param_env, callee_body, instance, penalty: 0, bonus: 0 }
     }
 
+    /// Add function-level costs not well-represented by the block-level costs.
+    ///
+    /// Needed because the `CostChecker` is used sometimes for just blocks,
+    /// and even the full `Inline` doesn't call `visit_body`, so there's nowhere
+    /// to put this logic in the visitor.
+    pub fn add_function_level_costs(&mut self) {
+        fn is_call_like(bbd: &BasicBlockData<'_>) -> bool {
+            use TerminatorKind::*;
+            match bbd.terminator().kind {
+                Call { .. } | Drop { .. } | Assert { .. } | InlineAsm { .. } => true,
+
+                Goto { .. }
+                | SwitchInt { .. }
+                | UnwindResume
+                | UnwindTerminate(_)
+                | Return
+                | Unreachable => false,
+
+                Yield { .. } | CoroutineDrop | FalseEdge { .. } | FalseUnwind { .. } => {
+                    unreachable!()
+                }
+            }
+        }
+
+        // If the only has one Call (or similar), inlining isn't increasing the total
+        // number of calls, so give extra encouragement to inlining that.
+        if self.callee_body.basic_blocks.iter().filter(|bbd| is_call_like(bbd)).count() == 1 {
+            self.bonus += CALL_PENALTY;
+        }
+    }
+
     pub fn cost(&self) -> usize {
         usize::saturating_sub(self.penalty, self.bonus)
     }
diff --git a/compiler/rustc_mir_transform/src/coverage/mappings.rs b/compiler/rustc_mir_transform/src/coverage/mappings.rs
index 759bb7c1f9d..235992ac547 100644
--- a/compiler/rustc_mir_transform/src/coverage/mappings.rs
+++ b/compiler/rustc_mir_transform/src/coverage/mappings.rs
@@ -9,9 +9,8 @@ use rustc_middle::ty::TyCtxt;
 use rustc_span::Span;
 
 use crate::coverage::graph::{BasicCoverageBlock, CoverageGraph, START_BCB};
-use crate::coverage::spans::{
-    extract_refined_covspans, unexpand_into_body_span_with_visible_macro,
-};
+use crate::coverage::spans::extract_refined_covspans;
+use crate::coverage::unexpand::unexpand_into_body_span;
 use crate::coverage::ExtractedHirInfo;
 
 /// Associates an ordinary executable code span with its corresponding BCB.
@@ -202,8 +201,7 @@ pub(super) fn extract_branch_pairs(
             if !raw_span.ctxt().outer_expn_data().is_root() {
                 return None;
             }
-            let (span, _) =
-                unexpand_into_body_span_with_visible_macro(raw_span, hir_info.body_span)?;
+            let span = unexpand_into_body_span(raw_span, hir_info.body_span)?;
 
             let bcb_from_marker =
                 |marker: BlockMarkerId| basic_coverage_blocks.bcb_from_bb(block_markers[marker]?);
@@ -238,7 +236,7 @@ pub(super) fn extract_mcdc_mappings(
             if !raw_span.ctxt().outer_expn_data().is_root() {
                 return None;
             }
-            let (span, _) = unexpand_into_body_span_with_visible_macro(raw_span, body_span)?;
+            let span = unexpand_into_body_span(raw_span, body_span)?;
 
             let true_bcb = bcb_from_marker(true_marker)?;
             let false_bcb = bcb_from_marker(false_marker)?;
@@ -261,7 +259,7 @@ pub(super) fn extract_mcdc_mappings(
 
     mcdc_decisions.extend(branch_info.mcdc_decision_spans.iter().filter_map(
         |decision: &mir::coverage::MCDCDecisionSpan| {
-            let (span, _) = unexpand_into_body_span_with_visible_macro(decision.span, body_span)?;
+            let span = unexpand_into_body_span(decision.span, body_span)?;
 
             let end_bcbs = decision
                 .end_markers
diff --git a/compiler/rustc_mir_transform/src/coverage/mod.rs b/compiler/rustc_mir_transform/src/coverage/mod.rs
index 4a64d21f3d1..d55bde311c1 100644
--- a/compiler/rustc_mir_transform/src/coverage/mod.rs
+++ b/compiler/rustc_mir_transform/src/coverage/mod.rs
@@ -6,6 +6,7 @@ mod mappings;
 mod spans;
 #[cfg(test)]
 mod tests;
+mod unexpand;
 
 use rustc_middle::mir::coverage::{
     CodeRegion, CoverageKind, DecisionInfo, FunctionCoverageInfo, Mapping, MappingKind,
diff --git a/compiler/rustc_mir_transform/src/coverage/spans.rs b/compiler/rustc_mir_transform/src/coverage/spans.rs
index 84a70d1f02d..7612c01c52e 100644
--- a/compiler/rustc_mir_transform/src/coverage/spans.rs
+++ b/compiler/rustc_mir_transform/src/coverage/spans.rs
@@ -14,11 +14,6 @@ use crate::coverage::ExtractedHirInfo;
 
 mod from_mir;
 
-// FIXME(#124545) It's awkward that we have to re-export this, because it's an
-// internal detail of `from_mir` that is also needed when handling branch and
-// MC/DC spans. Ideally we would find a more natural home for it.
-pub(super) use from_mir::unexpand_into_body_span_with_visible_macro;
-
 pub(super) fn extract_refined_covspans(
     mir_body: &mir::Body<'_>,
     hir_info: &ExtractedHirInfo,
diff --git a/compiler/rustc_mir_transform/src/coverage/spans/from_mir.rs b/compiler/rustc_mir_transform/src/coverage/spans/from_mir.rs
index 09deb7534bf..2ca166929ee 100644
--- a/compiler/rustc_mir_transform/src/coverage/spans/from_mir.rs
+++ b/compiler/rustc_mir_transform/src/coverage/spans/from_mir.rs
@@ -4,12 +4,13 @@ use rustc_middle::mir::{
     self, AggregateKind, FakeReadCause, Rvalue, Statement, StatementKind, Terminator,
     TerminatorKind,
 };
-use rustc_span::{ExpnKind, MacroKind, Span, Symbol};
+use rustc_span::{Span, Symbol};
 
 use crate::coverage::graph::{
     BasicCoverageBlock, BasicCoverageBlockData, CoverageGraph, START_BCB,
 };
 use crate::coverage::spans::Covspan;
+use crate::coverage::unexpand::unexpand_into_body_span_with_visible_macro;
 use crate::coverage::ExtractedHirInfo;
 
 pub(crate) struct ExtractedCovspans {
@@ -215,59 +216,6 @@ fn filtered_terminator_span(terminator: &Terminator<'_>) -> Option<Span> {
     }
 }
 
-/// Returns an extrapolated span (pre-expansion[^1]) corresponding to a range
-/// within the function's body source. This span is guaranteed to be contained
-/// within, or equal to, the `body_span`. If the extrapolated span is not
-/// contained within the `body_span`, `None` is returned.
-///
-/// [^1]Expansions result from Rust syntax including macros, syntactic sugar,
-/// etc.).
-pub(crate) fn unexpand_into_body_span_with_visible_macro(
-    original_span: Span,
-    body_span: Span,
-) -> Option<(Span, Option<Symbol>)> {
-    let (span, prev) = unexpand_into_body_span_with_prev(original_span, body_span)?;
-
-    let visible_macro = prev
-        .map(|prev| match prev.ctxt().outer_expn_data().kind {
-            ExpnKind::Macro(MacroKind::Bang, name) => Some(name),
-            _ => None,
-        })
-        .flatten();
-
-    Some((span, visible_macro))
-}
-
-/// Walks through the expansion ancestors of `original_span` to find a span that
-/// is contained in `body_span` and has the same [`SyntaxContext`] as `body_span`.
-/// The ancestor that was traversed just before the matching span (if any) is
-/// also returned.
-///
-/// For example, a return value of `Some((ancestor, Some(prev))` means that:
-/// - `ancestor == original_span.find_ancestor_inside_same_ctxt(body_span)`
-/// - `ancestor == prev.parent_callsite()`
-///
-/// [`SyntaxContext`]: rustc_span::SyntaxContext
-fn unexpand_into_body_span_with_prev(
-    original_span: Span,
-    body_span: Span,
-) -> Option<(Span, Option<Span>)> {
-    let mut prev = None;
-    let mut curr = original_span;
-
-    while !body_span.contains(curr) || !curr.eq_ctxt(body_span) {
-        prev = Some(curr);
-        curr = curr.parent_callsite()?;
-    }
-
-    debug_assert_eq!(Some(curr), original_span.find_ancestor_in_same_ctxt(body_span));
-    if let Some(prev) = prev {
-        debug_assert_eq!(Some(curr), prev.parent_callsite());
-    }
-
-    Some((curr, prev))
-}
-
 #[derive(Debug)]
 pub(crate) struct Hole {
     pub(crate) span: Span,
diff --git a/compiler/rustc_mir_transform/src/coverage/unexpand.rs b/compiler/rustc_mir_transform/src/coverage/unexpand.rs
new file mode 100644
index 00000000000..8cde291b907
--- /dev/null
+++ b/compiler/rustc_mir_transform/src/coverage/unexpand.rs
@@ -0,0 +1,60 @@
+use rustc_span::{ExpnKind, MacroKind, Span, Symbol};
+
+/// Walks through the expansion ancestors of `original_span` to find a span that
+/// is contained in `body_span` and has the same [syntax context] as `body_span`.
+pub(crate) fn unexpand_into_body_span(original_span: Span, body_span: Span) -> Option<Span> {
+    // Because we don't need to return any extra ancestor information,
+    // we can just delegate directly to `find_ancestor_inside_same_ctxt`.
+    original_span.find_ancestor_inside_same_ctxt(body_span)
+}
+
+/// Walks through the expansion ancestors of `original_span` to find a span that
+/// is contained in `body_span` and has the same [syntax context] as `body_span`.
+///
+/// If the returned span represents a bang-macro invocation (e.g. `foo!(..)`),
+/// the returned symbol will be the name of that macro (e.g. `foo`).
+pub(crate) fn unexpand_into_body_span_with_visible_macro(
+    original_span: Span,
+    body_span: Span,
+) -> Option<(Span, Option<Symbol>)> {
+    let (span, prev) = unexpand_into_body_span_with_prev(original_span, body_span)?;
+
+    let visible_macro = prev
+        .map(|prev| match prev.ctxt().outer_expn_data().kind {
+            ExpnKind::Macro(MacroKind::Bang, name) => Some(name),
+            _ => None,
+        })
+        .flatten();
+
+    Some((span, visible_macro))
+}
+
+/// Walks through the expansion ancestors of `original_span` to find a span that
+/// is contained in `body_span` and has the same [syntax context] as `body_span`.
+/// The ancestor that was traversed just before the matching span (if any) is
+/// also returned.
+///
+/// For example, a return value of `Some((ancestor, Some(prev)))` means that:
+/// - `ancestor == original_span.find_ancestor_inside_same_ctxt(body_span)`
+/// - `prev.parent_callsite() == ancestor`
+///
+/// [syntax context]: rustc_span::SyntaxContext
+fn unexpand_into_body_span_with_prev(
+    original_span: Span,
+    body_span: Span,
+) -> Option<(Span, Option<Span>)> {
+    let mut prev = None;
+    let mut curr = original_span;
+
+    while !body_span.contains(curr) || !curr.eq_ctxt(body_span) {
+        prev = Some(curr);
+        curr = curr.parent_callsite()?;
+    }
+
+    debug_assert_eq!(Some(curr), original_span.find_ancestor_inside_same_ctxt(body_span));
+    if let Some(prev) = prev {
+        debug_assert_eq!(Some(curr), prev.parent_callsite());
+    }
+
+    Some((curr, prev))
+}
diff --git a/compiler/rustc_mir_transform/src/dataflow_const_prop.rs b/compiler/rustc_mir_transform/src/dataflow_const_prop.rs
index 0fd85eb345d..8b965f4d18e 100644
--- a/compiler/rustc_mir_transform/src/dataflow_const_prop.rs
+++ b/compiler/rustc_mir_transform/src/dataflow_const_prop.rs
@@ -181,11 +181,6 @@ impl<'tcx> ValueAnalysis<'tcx> for ConstAnalysis<'_, 'tcx> {
                         state.insert_value_idx(value_target, val, self.map());
                     }
                     if let Some(overflow_target) = overflow_target {
-                        let overflow = match overflow {
-                            FlatSet::Top => FlatSet::Top,
-                            FlatSet::Elem(overflow) => FlatSet::Elem(overflow),
-                            FlatSet::Bottom => FlatSet::Bottom,
-                        };
                         // We have flooded `target` earlier.
                         state.insert_value_idx(overflow_target, overflow, self.map());
                     }
diff --git a/compiler/rustc_mir_transform/src/elaborate_drops.rs b/compiler/rustc_mir_transform/src/elaborate_drops.rs
index 665b2260294..fbbb8c5e472 100644
--- a/compiler/rustc_mir_transform/src/elaborate_drops.rs
+++ b/compiler/rustc_mir_transform/src/elaborate_drops.rs
@@ -97,7 +97,7 @@ impl<'tcx> MirPass<'tcx> for ElaborateDrops {
 #[instrument(level = "trace", skip(body, flow_inits), ret)]
 fn compute_dead_unwinds<'mir, 'tcx>(
     body: &'mir Body<'tcx>,
-    flow_inits: &mut ResultsCursor<'mir, 'tcx, MaybeInitializedPlaces<'mir, 'tcx>>,
+    flow_inits: &mut ResultsCursor<'mir, 'tcx, MaybeInitializedPlaces<'_, 'mir, 'tcx>>,
 ) -> BitSet<BasicBlock> {
     // We only need to do this pass once, because unwind edges can only
     // reach cleanup blocks, which can't have unwind edges themselves.
@@ -118,12 +118,12 @@ fn compute_dead_unwinds<'mir, 'tcx>(
     dead_unwinds
 }
 
-struct InitializationData<'mir, 'tcx> {
-    inits: ResultsCursor<'mir, 'tcx, MaybeInitializedPlaces<'mir, 'tcx>>,
-    uninits: ResultsCursor<'mir, 'tcx, MaybeUninitializedPlaces<'mir, 'tcx>>,
+struct InitializationData<'a, 'mir, 'tcx> {
+    inits: ResultsCursor<'mir, 'tcx, MaybeInitializedPlaces<'a, 'mir, 'tcx>>,
+    uninits: ResultsCursor<'mir, 'tcx, MaybeUninitializedPlaces<'a, 'mir, 'tcx>>,
 }
 
-impl InitializationData<'_, '_> {
+impl InitializationData<'_, '_, '_> {
     fn seek_before(&mut self, loc: Location) {
         self.inits.seek_before_primary_effect(loc);
         self.uninits.seek_before_primary_effect(loc);
@@ -134,17 +134,17 @@ impl InitializationData<'_, '_> {
     }
 }
 
-struct Elaborator<'a, 'b, 'tcx> {
-    ctxt: &'a mut ElaborateDropsCtxt<'b, 'tcx>,
+struct Elaborator<'a, 'b, 'mir, 'tcx> {
+    ctxt: &'a mut ElaborateDropsCtxt<'b, 'mir, 'tcx>,
 }
 
-impl fmt::Debug for Elaborator<'_, '_, '_> {
+impl fmt::Debug for Elaborator<'_, '_, '_, '_> {
     fn fmt(&self, _f: &mut fmt::Formatter<'_>) -> fmt::Result {
         Ok(())
     }
 }
 
-impl<'a, 'tcx> DropElaborator<'a, 'tcx> for Elaborator<'a, '_, 'tcx> {
+impl<'a, 'tcx> DropElaborator<'a, 'tcx> for Elaborator<'a, '_, '_, 'tcx> {
     type Path = MovePathIndex;
 
     fn patch(&mut self) -> &mut MirPatch<'tcx> {
@@ -238,16 +238,16 @@ impl<'a, 'tcx> DropElaborator<'a, 'tcx> for Elaborator<'a, '_, 'tcx> {
     }
 }
 
-struct ElaborateDropsCtxt<'a, 'tcx> {
+struct ElaborateDropsCtxt<'a, 'mir, 'tcx> {
     tcx: TyCtxt<'tcx>,
-    body: &'a Body<'tcx>,
+    body: &'mir Body<'tcx>,
     env: &'a MoveDataParamEnv<'tcx>,
-    init_data: InitializationData<'a, 'tcx>,
+    init_data: InitializationData<'a, 'mir, 'tcx>,
     drop_flags: IndexVec<MovePathIndex, Option<Local>>,
     patch: MirPatch<'tcx>,
 }
 
-impl<'b, 'tcx> ElaborateDropsCtxt<'b, 'tcx> {
+impl<'b, 'mir, 'tcx> ElaborateDropsCtxt<'b, 'mir, 'tcx> {
     fn move_data(&self) -> &'b MoveData<'tcx> {
         &self.env.move_data
     }
diff --git a/compiler/rustc_mir_transform/src/gvn.rs b/compiler/rustc_mir_transform/src/gvn.rs
index 936a7e2d9de..3dbdeb615cf 100644
--- a/compiler/rustc_mir_transform/src/gvn.rs
+++ b/compiler/rustc_mir_transform/src/gvn.rs
@@ -1074,11 +1074,11 @@ impl<'body, 'tcx> VnState<'body, 'tcx> {
         {
             lhs = *lhs_value;
             rhs = *rhs_value;
-            if let Some(op) = self.try_as_operand(lhs, location) {
-                *lhs_operand = op;
-            }
-            if let Some(op) = self.try_as_operand(rhs, location) {
-                *rhs_operand = op;
+            if let Some(lhs_op) = self.try_as_operand(lhs, location)
+                && let Some(rhs_op) = self.try_as_operand(rhs, location)
+            {
+                *lhs_operand = lhs_op;
+                *rhs_operand = rhs_op;
             }
         }
 
diff --git a/compiler/rustc_mir_transform/src/inline.rs b/compiler/rustc_mir_transform/src/inline.rs
index 0a5fc697d03..6fa31c1174d 100644
--- a/compiler/rustc_mir_transform/src/inline.rs
+++ b/compiler/rustc_mir_transform/src/inline.rs
@@ -11,7 +11,7 @@ use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs}
 use rustc_middle::mir::visit::*;
 use rustc_middle::mir::*;
 use rustc_middle::ty::TypeVisitableExt;
-use rustc_middle::ty::{self, Instance, InstanceKind, ParamEnv, Ty, TyCtxt};
+use rustc_middle::ty::{self, Instance, InstanceKind, ParamEnv, Ty, TyCtxt, TypeFlags};
 use rustc_session::config::{DebugInfo, OptLevel};
 use rustc_span::source_map::Spanned;
 use rustc_span::sym;
@@ -85,13 +85,18 @@ fn inline<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) -> bool {
     }
 
     let param_env = tcx.param_env_reveal_all_normalized(def_id);
+    let codegen_fn_attrs = tcx.codegen_fn_attrs(def_id);
 
     let mut this = Inliner {
         tcx,
         param_env,
-        codegen_fn_attrs: tcx.codegen_fn_attrs(def_id),
+        codegen_fn_attrs,
         history: Vec::new(),
         changed: false,
+        caller_is_inline_forwarder: matches!(
+            codegen_fn_attrs.inline,
+            InlineAttr::Hint | InlineAttr::Always
+        ) && body_is_forwarder(body),
     };
     let blocks = START_BLOCK..body.basic_blocks.next_index();
     this.process_blocks(body, blocks);
@@ -111,6 +116,9 @@ struct Inliner<'tcx> {
     history: Vec<DefId>,
     /// Indicates that the caller body has been modified.
     changed: bool,
+    /// Indicates that the caller is #[inline] and just calls another function,
+    /// and thus we can inline less into it as it'll be inlined itself.
+    caller_is_inline_forwarder: bool,
 }
 
 impl<'tcx> Inliner<'tcx> {
@@ -306,6 +314,16 @@ impl<'tcx> Inliner<'tcx> {
             InstanceKind::Intrinsic(_) | InstanceKind::Virtual(..) => {
                 return Err("instance without MIR (intrinsic / virtual)");
             }
+
+            // FIXME(#127030): `ConstParamHasTy` has bad interactions with
+            // the drop shim builder, which does not evaluate predicates in
+            // the correct param-env for types being dropped. Stall resolving
+            // the MIR for this instance until all of its const params are
+            // substituted.
+            InstanceKind::DropGlue(_, Some(ty)) if ty.has_type_flags(TypeFlags::HAS_CT_PARAM) => {
+                return Err("still needs substitution");
+            }
+
             // This cannot result in an immediate cycle since the callee MIR is a shim, which does
             // not get any optimizations run on it. Any subsequent inlining may cause cycles, but we
             // do not need to catch this here, we can wait until the inliner decides to continue
@@ -475,7 +493,9 @@ impl<'tcx> Inliner<'tcx> {
     ) -> Result<(), &'static str> {
         let tcx = self.tcx;
 
-        let mut threshold = if cross_crate_inlinable {
+        let mut threshold = if self.caller_is_inline_forwarder {
+            self.tcx.sess.opts.unstable_opts.inline_mir_forwarder_threshold.unwrap_or(30)
+        } else if cross_crate_inlinable {
             self.tcx.sess.opts.unstable_opts.inline_mir_hint_threshold.unwrap_or(100)
         } else {
             self.tcx.sess.opts.unstable_opts.inline_mir_threshold.unwrap_or(50)
@@ -494,6 +514,8 @@ impl<'tcx> Inliner<'tcx> {
         let mut checker =
             CostChecker::new(self.tcx, self.param_env, Some(callsite.callee), callee_body);
 
+        checker.add_function_level_costs();
+
         // Traverse the MIR manually so we can account for the effects of inlining on the CFG.
         let mut work_list = vec![START_BLOCK];
         let mut visited = BitSet::new_empty(callee_body.basic_blocks.len());
@@ -1081,3 +1103,37 @@ fn try_instance_mir<'tcx>(
     }
     Ok(tcx.instance_mir(instance))
 }
+
+fn body_is_forwarder(body: &Body<'_>) -> bool {
+    let TerminatorKind::Call { target, .. } = body.basic_blocks[START_BLOCK].terminator().kind
+    else {
+        return false;
+    };
+    if let Some(target) = target {
+        let TerminatorKind::Return = body.basic_blocks[target].terminator().kind else {
+            return false;
+        };
+    }
+
+    let max_blocks = if !body.is_polymorphic {
+        2
+    } else if target.is_none() {
+        3
+    } else {
+        4
+    };
+    if body.basic_blocks.len() > max_blocks {
+        return false;
+    }
+
+    body.basic_blocks.iter_enumerated().all(|(bb, bb_data)| {
+        bb == START_BLOCK
+            || matches!(
+                bb_data.terminator().kind,
+                TerminatorKind::Return
+                    | TerminatorKind::Drop { .. }
+                    | TerminatorKind::UnwindResume
+                    | TerminatorKind::UnwindTerminate(_)
+            )
+    })
+}
diff --git a/compiler/rustc_mir_transform/src/jump_threading.rs b/compiler/rustc_mir_transform/src/jump_threading.rs
index 23cc0c46e73..27e506a920b 100644
--- a/compiler/rustc_mir_transform/src/jump_threading.rs
+++ b/compiler/rustc_mir_transform/src/jump_threading.rs
@@ -91,43 +91,8 @@ impl<'tcx> MirPass<'tcx> for JumpThreading {
             opportunities: Vec::new(),
         };
 
-        for (bb, bbdata) in body.basic_blocks.iter_enumerated() {
-            debug!(?bb, term = ?bbdata.terminator());
-            if bbdata.is_cleanup || loop_headers.contains(bb) {
-                continue;
-            }
-            let Some((discr, targets)) = bbdata.terminator().kind.as_switch() else { continue };
-            let Some(discr) = discr.place() else { continue };
-            debug!(?discr, ?bb);
-
-            let discr_ty = discr.ty(body, tcx).ty;
-            let Ok(discr_layout) = finder.ecx.layout_of(discr_ty) else { continue };
-
-            let Some(discr) = finder.map.find(discr.as_ref()) else { continue };
-            debug!(?discr);
-
-            let cost = CostChecker::new(tcx, param_env, None, body);
-
-            let mut state = State::new(ConditionSet::default(), finder.map);
-
-            let conds = if let Some((value, then, else_)) = targets.as_static_if() {
-                let Some(value) = ScalarInt::try_from_uint(value, discr_layout.size) else {
-                    continue;
-                };
-                arena.alloc_from_iter([
-                    Condition { value, polarity: Polarity::Eq, target: then },
-                    Condition { value, polarity: Polarity::Ne, target: else_ },
-                ])
-            } else {
-                arena.alloc_from_iter(targets.iter().filter_map(|(value, target)| {
-                    let value = ScalarInt::try_from_uint(value, discr_layout.size)?;
-                    Some(Condition { value, polarity: Polarity::Eq, target })
-                }))
-            };
-            let conds = ConditionSet(conds);
-            state.insert_value_idx(discr, conds, finder.map);
-
-            finder.find_opportunity(bb, state, cost, 0);
+        for bb in body.basic_blocks.indices() {
+            finder.start_from_switch(bb);
         }
 
         let opportunities = finder.opportunities;
@@ -216,6 +181,46 @@ impl<'tcx, 'a> TOFinder<'tcx, 'a> {
     }
 
     /// Recursion entry point to find threading opportunities.
+    #[instrument(level = "trace", skip(self))]
+    fn start_from_switch(&mut self, bb: BasicBlock) -> Option<!> {
+        let bbdata = &self.body[bb];
+        if bbdata.is_cleanup || self.loop_headers.contains(bb) {
+            return None;
+        }
+        let (discr, targets) = bbdata.terminator().kind.as_switch()?;
+        let discr = discr.place()?;
+        debug!(?discr, ?bb);
+
+        let discr_ty = discr.ty(self.body, self.tcx).ty;
+        let discr_layout = self.ecx.layout_of(discr_ty).ok()?;
+
+        let discr = self.map.find(discr.as_ref())?;
+        debug!(?discr);
+
+        let cost = CostChecker::new(self.tcx, self.param_env, None, self.body);
+        let mut state = State::new(ConditionSet::default(), self.map);
+
+        let conds = if let Some((value, then, else_)) = targets.as_static_if() {
+            let value = ScalarInt::try_from_uint(value, discr_layout.size)?;
+            self.arena.alloc_from_iter([
+                Condition { value, polarity: Polarity::Eq, target: then },
+                Condition { value, polarity: Polarity::Ne, target: else_ },
+            ])
+        } else {
+            self.arena.alloc_from_iter(targets.iter().filter_map(|(value, target)| {
+                let value = ScalarInt::try_from_uint(value, discr_layout.size)?;
+                Some(Condition { value, polarity: Polarity::Eq, target })
+            }))
+        };
+        let conds = ConditionSet(conds);
+        state.insert_value_idx(discr, conds, self.map);
+
+        self.find_opportunity(bb, state, cost, 0);
+        None
+    }
+
+    /// Recursively walk statements backwards from this bb's terminator to find threading
+    /// opportunities.
     #[instrument(level = "trace", skip(self, cost), ret)]
     fn find_opportunity(
         &mut self,
@@ -270,12 +275,13 @@ impl<'tcx, 'a> TOFinder<'tcx, 'a> {
                     self.process_switch_int(discr, targets, bb, &mut state);
                     self.find_opportunity(pred, state, cost, depth + 1);
                 }
-                _ => self.recurse_through_terminator(pred, &state, &cost, depth),
+                _ => self.recurse_through_terminator(pred, || state, &cost, depth),
             }
-        } else {
+        } else if let &[ref predecessors @ .., last_pred] = &predecessors[..] {
             for &pred in predecessors {
-                self.recurse_through_terminator(pred, &state, &cost, depth);
+                self.recurse_through_terminator(pred, || state.clone(), &cost, depth);
             }
+            self.recurse_through_terminator(last_pred, || state, &cost, depth);
         }
 
         let new_tos = &mut self.opportunities[last_non_rec..];
@@ -566,11 +572,12 @@ impl<'tcx, 'a> TOFinder<'tcx, 'a> {
         None
     }
 
-    #[instrument(level = "trace", skip(self, cost))]
+    #[instrument(level = "trace", skip(self, state, cost))]
     fn recurse_through_terminator(
         &mut self,
         bb: BasicBlock,
-        state: &State<ConditionSet<'a>>,
+        // Pass a closure that may clone the state, as we don't want to do it each time.
+        state: impl FnOnce() -> State<ConditionSet<'a>>,
         cost: &CostChecker<'_, 'tcx>,
         depth: usize,
     ) {
@@ -600,7 +607,7 @@ impl<'tcx, 'a> TOFinder<'tcx, 'a> {
         };
 
         // We can recurse through this terminator.
-        let mut state = state.clone();
+        let mut state = state();
         if let Some(place_to_flood) = place_to_flood {
             state.flood_with(place_to_flood.as_ref(), self.map, ConditionSet::default());
         }
diff --git a/compiler/rustc_next_trait_solver/src/solve/assembly/mod.rs b/compiler/rustc_next_trait_solver/src/solve/assembly/mod.rs
index 21439530c08..6ee684605ac 100644
--- a/compiler/rustc_next_trait_solver/src/solve/assembly/mod.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/assembly/mod.rs
@@ -269,6 +269,11 @@ where
         ecx: &mut EvalCtxt<'_, D>,
         goal: Goal<I, Self>,
     ) -> Vec<Candidate<I>>;
+
+    fn consider_builtin_effects_intersection_candidate(
+        ecx: &mut EvalCtxt<'_, D>,
+        goal: Goal<I, Self>,
+    ) -> Result<Candidate<I>, NoSolution>;
 }
 
 impl<D, I> EvalCtxt<'_, D>
@@ -420,6 +425,8 @@ where
             G::consider_builtin_destruct_candidate(self, goal)
         } else if cx.is_lang_item(trait_def_id, TraitSolverLangItem::TransmuteTrait) {
             G::consider_builtin_transmute_candidate(self, goal)
+        } else if cx.is_lang_item(trait_def_id, TraitSolverLangItem::EffectsIntersection) {
+            G::consider_builtin_effects_intersection_candidate(self, goal)
         } else {
             Err(NoSolution)
         };
diff --git a/compiler/rustc_next_trait_solver/src/solve/assembly/structural_traits.rs b/compiler/rustc_next_trait_solver/src/solve/assembly/structural_traits.rs
index 0cef8d9f4bc..3447b39fa5b 100644
--- a/compiler/rustc_next_trait_solver/src/solve/assembly/structural_traits.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/assembly/structural_traits.rs
@@ -668,8 +668,9 @@ where
 {
     let cx = ecx.cx();
     let mut requirements = vec![];
-    requirements
-        .extend(cx.super_predicates_of(trait_ref.def_id).iter_instantiated(cx, trait_ref.args));
+    requirements.extend(
+        cx.explicit_super_predicates_of(trait_ref.def_id).iter_instantiated(cx, trait_ref.args),
+    );
 
     // FIXME(associated_const_equality): Also add associated consts to
     // the requirements here.
diff --git a/compiler/rustc_next_trait_solver/src/solve/normalizes_to/mod.rs b/compiler/rustc_next_trait_solver/src/solve/normalizes_to/mod.rs
index 4e8cb4384f4..9275bcc8e97 100644
--- a/compiler/rustc_next_trait_solver/src/solve/normalizes_to/mod.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/normalizes_to/mod.rs
@@ -864,6 +864,68 @@ where
     ) -> Result<Candidate<I>, NoSolution> {
         panic!("`BikeshedIntrinsicFrom` does not have an associated type: {:?}", goal)
     }
+
+    fn consider_builtin_effects_intersection_candidate(
+        ecx: &mut EvalCtxt<'_, D>,
+        goal: Goal<I, Self>,
+    ) -> Result<Candidate<I>, NoSolution> {
+        let ty::Tuple(types) = goal.predicate.self_ty().kind() else {
+            return Err(NoSolution);
+        };
+
+        let cx = ecx.cx();
+
+        let mut first_non_maybe = None;
+        let mut non_maybe_count = 0;
+        for ty in types.iter() {
+            if !matches!(ty::EffectKind::try_from_ty(cx, ty), Some(ty::EffectKind::Maybe)) {
+                first_non_maybe.get_or_insert(ty);
+                non_maybe_count += 1;
+            }
+        }
+
+        match non_maybe_count {
+            0 => {
+                let ty = ty::EffectKind::Maybe.to_ty(cx);
+                ecx.probe_builtin_trait_candidate(BuiltinImplSource::Misc).enter(|ecx| {
+                    ecx.instantiate_normalizes_to_term(goal, ty.into());
+                    ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
+                })
+            }
+            1 => {
+                let ty = first_non_maybe.unwrap();
+                ecx.probe_builtin_trait_candidate(BuiltinImplSource::Misc).enter(|ecx| {
+                    ecx.instantiate_normalizes_to_term(goal, ty.into());
+                    ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
+                })
+            }
+            _ => {
+                let mut min = ty::EffectKind::Maybe;
+
+                for ty in types.iter() {
+                    // We can't find the intersection if the types used are generic.
+                    //
+                    // FIXME(effects) do we want to look at where clauses to get some
+                    // clue for the case where generic types are being used?
+                    let Some(kind) = ty::EffectKind::try_from_ty(cx, ty) else {
+                        return Err(NoSolution);
+                    };
+
+                    let Some(result) = ty::EffectKind::intersection(min, kind) else {
+                        return Err(NoSolution);
+                    };
+
+                    min = result;
+                }
+
+                let ty = min.to_ty(cx);
+                ecx.probe_builtin_trait_candidate(BuiltinImplSource::Misc).enter(|ecx| {
+                    ecx.instantiate_normalizes_to_term(goal, ty.into());
+                    ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
+                })
+            }
+        }
+    }
 }
 
 impl<D, I> EvalCtxt<'_, D>
diff --git a/compiler/rustc_next_trait_solver/src/solve/trait_goals.rs b/compiler/rustc_next_trait_solver/src/solve/trait_goals.rs
index 2bc9d35c2b0..f5832f7e5b4 100644
--- a/compiler/rustc_next_trait_solver/src/solve/trait_goals.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/trait_goals.rs
@@ -702,6 +702,47 @@ where
             }
         })
     }
+
+    fn consider_builtin_effects_intersection_candidate(
+        ecx: &mut EvalCtxt<'_, D>,
+        goal: Goal<I, Self>,
+    ) -> Result<Candidate<I>, NoSolution> {
+        if goal.predicate.polarity != ty::PredicatePolarity::Positive {
+            return Err(NoSolution);
+        }
+
+        let ty::Tuple(types) = goal.predicate.self_ty().kind() else {
+            return Err(NoSolution);
+        };
+
+        let cx = ecx.cx();
+        let maybe_count = types
+            .iter()
+            .filter_map(|ty| ty::EffectKind::try_from_ty(cx, ty))
+            .filter(|&ty| ty == ty::EffectKind::Maybe)
+            .count();
+
+        // Don't do concrete type check unless there are more than one type that will influence the result.
+        // This would allow `(Maybe, T): Min` pass even if we know nothing about `T`.
+        if types.len() - maybe_count > 1 {
+            let mut min = ty::EffectKind::Maybe;
+
+            for ty in types.iter() {
+                let Some(kind) = ty::EffectKind::try_from_ty(ecx.cx(), ty) else {
+                    return Err(NoSolution);
+                };
+
+                let Some(result) = ty::EffectKind::intersection(min, kind) else {
+                    return Err(NoSolution);
+                };
+
+                min = result;
+            }
+        }
+
+        ecx.probe_builtin_trait_candidate(BuiltinImplSource::Misc)
+            .enter(|ecx| ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes))
+    }
 }
 
 impl<D, I> EvalCtxt<'_, D>
diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index 3cdc20b6c65..b2df9a14eb0 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
@@ -2327,7 +2327,7 @@ impl<'a> Parser<'a> {
         let before = self.prev_token.clone();
         let binder = if self.check_keyword(kw::For) {
             let lo = self.token.span;
-            let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
+            let (lifetime_defs, _) = self.parse_late_bound_lifetime_defs()?;
             let span = lo.to(self.prev_token.span);
 
             self.psess.gated_spans.gate(sym::closure_lifetime_binder, span);
diff --git a/compiler/rustc_parse/src/parser/generics.rs b/compiler/rustc_parse/src/parser/generics.rs
index fde16ac957d..10c7715c7dc 100644
--- a/compiler/rustc_parse/src/parser/generics.rs
+++ b/compiler/rustc_parse/src/parser/generics.rs
@@ -457,7 +457,7 @@ impl<'a> Parser<'a> {
         // * `for<'a> Trait1<'a>: Trait2<'a /* ok */>`
         // * `(for<'a> Trait1<'a>): Trait2<'a /* not ok */>`
         // * `for<'a> for<'b> Trait1<'a, 'b>: Trait2<'a /* ok */, 'b /* not ok */>`
-        let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
+        let (lifetime_defs, _) = self.parse_late_bound_lifetime_defs()?;
 
         // Parse type with mandatory colon and (possibly empty) bounds,
         // or with mandatory equality sign and the second type.
diff --git a/compiler/rustc_parse/src/parser/ty.rs b/compiler/rustc_parse/src/parser/ty.rs
index d2043c353fe..1e5b227aaa9 100644
--- a/compiler/rustc_parse/src/parser/ty.rs
+++ b/compiler/rustc_parse/src/parser/ty.rs
@@ -18,7 +18,7 @@ use rustc_ast::{
 };
 use rustc_errors::{Applicability, PResult};
 use rustc_span::symbol::{kw, sym, Ident};
-use rustc_span::{Span, Symbol};
+use rustc_span::{ErrorGuaranteed, Span, Symbol};
 use thin_vec::{thin_vec, ThinVec};
 
 #[derive(Copy, Clone, PartialEq)]
@@ -280,7 +280,7 @@ impl<'a> Parser<'a> {
             // Function pointer type or bound list (trait object type) starting with a poly-trait.
             //   `for<'lt> [unsafe] [extern "ABI"] fn (&'lt S) -> T`
             //   `for<'lt> Trait1<'lt> + Trait2 + 'a`
-            let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
+            let (lifetime_defs, _) = self.parse_late_bound_lifetime_defs()?;
             if self.check_fn_front_matter(false, Case::Sensitive) {
                 self.parse_ty_bare_fn(
                     lo,
@@ -833,12 +833,9 @@ impl<'a> Parser<'a> {
         let lo = self.token.span;
         let leading_token = self.prev_token.clone();
         let has_parens = self.eat(&token::OpenDelim(Delimiter::Parenthesis));
-        let inner_lo = self.token.span;
 
-        let modifiers = self.parse_trait_bound_modifiers()?;
         let bound = if self.token.is_lifetime() {
-            self.error_lt_bound_with_modifiers(modifiers);
-            self.parse_generic_lt_bound(lo, inner_lo, has_parens)?
+            self.parse_generic_lt_bound(lo, has_parens)?
         } else if self.eat_keyword(kw::Use) {
             // parse precise captures, if any. This is `use<'lt, 'lt, P, P>`; a list of
             // lifetimes and ident params (including SelfUpper). These are validated later
@@ -848,7 +845,7 @@ impl<'a> Parser<'a> {
             let (args, args_span) = self.parse_precise_capturing_args()?;
             GenericBound::Use(args, use_span.to(args_span))
         } else {
-            self.parse_generic_ty_bound(lo, has_parens, modifiers, &leading_token)?
+            self.parse_generic_ty_bound(lo, has_parens, &leading_token)?
         };
 
         Ok(bound)
@@ -858,50 +855,64 @@ impl<'a> Parser<'a> {
     /// ```ebnf
     /// LT_BOUND = LIFETIME
     /// ```
-    fn parse_generic_lt_bound(
-        &mut self,
-        lo: Span,
-        inner_lo: Span,
-        has_parens: bool,
-    ) -> PResult<'a, GenericBound> {
-        let bound = GenericBound::Outlives(self.expect_lifetime());
+    fn parse_generic_lt_bound(&mut self, lo: Span, has_parens: bool) -> PResult<'a, GenericBound> {
+        let lt = self.expect_lifetime();
+        let bound = GenericBound::Outlives(lt);
         if has_parens {
             // FIXME(Centril): Consider not erroring here and accepting `('lt)` instead,
             // possibly introducing `GenericBound::Paren(P<GenericBound>)`?
-            self.recover_paren_lifetime(lo, inner_lo)?;
+            self.recover_paren_lifetime(lo, lt.ident.span)?;
         }
         Ok(bound)
     }
 
     /// Emits an error if any trait bound modifiers were present.
-    fn error_lt_bound_with_modifiers(&self, modifiers: TraitBoundModifiers) {
-        match modifiers.constness {
+    fn error_lt_bound_with_modifiers(
+        &self,
+        modifiers: TraitBoundModifiers,
+        binder_span: Option<Span>,
+    ) -> ErrorGuaranteed {
+        let TraitBoundModifiers { constness, asyncness, polarity } = modifiers;
+
+        match constness {
             BoundConstness::Never => {}
             BoundConstness::Always(span) | BoundConstness::Maybe(span) => {
-                self.dcx().emit_err(errors::ModifierLifetime {
-                    span,
-                    modifier: modifiers.constness.as_str(),
-                });
+                return self
+                    .dcx()
+                    .emit_err(errors::ModifierLifetime { span, modifier: constness.as_str() });
             }
         }
 
-        match modifiers.polarity {
+        match polarity {
             BoundPolarity::Positive => {}
             BoundPolarity::Negative(span) | BoundPolarity::Maybe(span) => {
-                self.dcx().emit_err(errors::ModifierLifetime {
-                    span,
-                    modifier: modifiers.polarity.as_str(),
-                });
+                return self
+                    .dcx()
+                    .emit_err(errors::ModifierLifetime { span, modifier: polarity.as_str() });
+            }
+        }
+
+        match asyncness {
+            BoundAsyncness::Normal => {}
+            BoundAsyncness::Async(span) => {
+                return self
+                    .dcx()
+                    .emit_err(errors::ModifierLifetime { span, modifier: asyncness.as_str() });
             }
         }
+
+        if let Some(span) = binder_span {
+            return self.dcx().emit_err(errors::ModifierLifetime { span, modifier: "for<...>" });
+        }
+
+        unreachable!("lifetime bound intercepted in `parse_generic_ty_bound` but no modifiers?")
     }
 
     /// Recover on `('lifetime)` with `(` already eaten.
-    fn recover_paren_lifetime(&mut self, lo: Span, inner_lo: Span) -> PResult<'a, ()> {
-        let inner_span = inner_lo.to(self.prev_token.span);
+    fn recover_paren_lifetime(&mut self, lo: Span, lt_span: Span) -> PResult<'a, ()> {
         self.expect(&token::CloseDelim(Delimiter::Parenthesis))?;
         let span = lo.to(self.prev_token.span);
-        let (sugg, snippet) = if let Ok(snippet) = self.span_to_snippet(inner_span) {
+        let (sugg, snippet) = if let Ok(snippet) = self.span_to_snippet(lt_span) {
             (Some(span), snippet)
         } else {
             (None, String::new())
@@ -916,7 +927,7 @@ impl<'a> Parser<'a> {
     /// If no modifiers are present, this does not consume any tokens.
     ///
     /// ```ebnf
-    /// TRAIT_BOUND_MODIFIERS = [["~"] "const"] ["?" | "!"]
+    /// TRAIT_BOUND_MODIFIERS = [["~"] "const"] ["async"] ["?" | "!"]
     /// ```
     fn parse_trait_bound_modifiers(&mut self) -> PResult<'a, TraitBoundModifiers> {
         let constness = if self.eat(&token::Tilde) {
@@ -970,15 +981,23 @@ impl<'a> Parser<'a> {
     /// TY_BOUND_NOPAREN = [TRAIT_BOUND_MODIFIERS] [for<LT_PARAM_DEFS>] SIMPLE_PATH
     /// ```
     ///
-    /// For example, this grammar accepts `~const ?for<'a: 'b> m::Trait<'a>`.
+    /// For example, this grammar accepts `for<'a: 'b> ~const ?m::Trait<'a>`.
     fn parse_generic_ty_bound(
         &mut self,
         lo: Span,
         has_parens: bool,
-        modifiers: TraitBoundModifiers,
         leading_token: &Token,
     ) -> PResult<'a, GenericBound> {
-        let mut lifetime_defs = self.parse_late_bound_lifetime_defs()?;
+        let modifiers = self.parse_trait_bound_modifiers()?;
+        let (mut lifetime_defs, binder_span) = self.parse_late_bound_lifetime_defs()?;
+
+        // Recover erroneous lifetime bound with modifiers or binder.
+        // e.g. `T: for<'a> 'a` or `T: ~const 'a`.
+        if self.token.is_lifetime() {
+            let _: ErrorGuaranteed = self.error_lt_bound_with_modifiers(modifiers, binder_span);
+            return self.parse_generic_lt_bound(lo, has_parens);
+        }
+
         let mut path = if self.token.is_keyword(kw::Fn)
             && self.look_ahead(1, |tok| tok.kind == TokenKind::OpenDelim(Delimiter::Parenthesis))
             && let Some(path) = self.recover_path_from_fn()
@@ -1094,16 +1113,19 @@ impl<'a> Parser<'a> {
     }
 
     /// Optionally parses `for<$generic_params>`.
-    pub(super) fn parse_late_bound_lifetime_defs(&mut self) -> PResult<'a, ThinVec<GenericParam>> {
+    pub(super) fn parse_late_bound_lifetime_defs(
+        &mut self,
+    ) -> PResult<'a, (ThinVec<GenericParam>, Option<Span>)> {
         if self.eat_keyword(kw::For) {
+            let lo = self.token.span;
             self.expect_lt()?;
             let params = self.parse_generic_params()?;
             self.expect_gt()?;
-            // We rely on AST validation to rule out invalid cases: There must not be type
-            // parameters, and the lifetime parameters must not have bounds.
-            Ok(params)
+            // We rely on AST validation to rule out invalid cases: There must not be
+            // type or const parameters, and parameters must not have bounds.
+            Ok((params, Some(lo.to(self.prev_token.span))))
         } else {
-            Ok(ThinVec::new())
+            Ok((ThinVec::new(), None))
         }
     }
 
diff --git a/compiler/rustc_passes/messages.ftl b/compiler/rustc_passes/messages.ftl
index 5a560325ab9..d7513fbad63 100644
--- a/compiler/rustc_passes/messages.ftl
+++ b/compiler/rustc_passes/messages.ftl
@@ -782,6 +782,7 @@ passes_used_compiler_linker =
 
 passes_used_static =
     attribute must be applied to a `static` variable
+    .label = but this is a {$target}
 
 passes_useless_assignment =
     useless assignment of {$is_field_assign ->
diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs
index 5f8e4a8b7a7..0eb9d1ce59f 100644
--- a/compiler/rustc_passes/src/check_attr.rs
+++ b/compiler/rustc_passes/src/check_attr.rs
@@ -274,7 +274,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         }
 
         self.check_repr(attrs, span, target, item, hir_id);
-        self.check_used(attrs, target);
+        self.check_used(attrs, target, span);
     }
 
     fn inline_attr_str_error_with_macro_def(&self, hir_id: HirId, attr: &Attribute, sym: &str) {
@@ -1930,12 +1930,16 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         }
     }
 
-    fn check_used(&self, attrs: &[Attribute], target: Target) {
+    fn check_used(&self, attrs: &[Attribute], target: Target, target_span: Span) {
         let mut used_linker_span = None;
         let mut used_compiler_span = None;
         for attr in attrs.iter().filter(|attr| attr.has_name(sym::used)) {
             if target != Target::Static {
-                self.dcx().emit_err(errors::UsedStatic { span: attr.span });
+                self.dcx().emit_err(errors::UsedStatic {
+                    attr_span: attr.span,
+                    span: target_span,
+                    target: target.name(),
+                });
             }
             let inner = attr.meta_item_list();
             match inner.as_deref() {
diff --git a/compiler/rustc_passes/src/errors.rs b/compiler/rustc_passes/src/errors.rs
index 7734dba3670..a026ff3b13b 100644
--- a/compiler/rustc_passes/src/errors.rs
+++ b/compiler/rustc_passes/src/errors.rs
@@ -551,7 +551,10 @@ pub struct ReprConflictingLint;
 #[diag(passes_used_static)]
 pub struct UsedStatic {
     #[primary_span]
+    pub attr_span: Span,
+    #[label]
     pub span: Span,
+    pub target: &'static str,
 }
 
 #[derive(Diagnostic)]
diff --git a/compiler/rustc_session/src/options.rs b/compiler/rustc_session/src/options.rs
index 80f7ca544f3..2e4421d50e3 100644
--- a/compiler/rustc_session/src/options.rs
+++ b/compiler/rustc_session/src/options.rs
@@ -1766,6 +1766,8 @@ options! {
         "enable LLVM inlining (default: yes)"),
     inline_mir: Option<bool> = (None, parse_opt_bool, [TRACKED],
         "enable MIR inlining (default: no)"),
+    inline_mir_forwarder_threshold: Option<usize> = (None, parse_opt_number, [TRACKED],
+        "inlining threshold when the caller is a simple forwarding function (default: 30)"),
     inline_mir_hint_threshold: Option<usize> = (None, parse_opt_number, [TRACKED],
         "inlining threshold for functions with inline hint (default: 100)"),
     inline_mir_preserve_debug: Option<bool> = (None, parse_opt_bool, [TRACKED],
diff --git a/compiler/rustc_smir/src/rustc_smir/context.rs b/compiler/rustc_smir/src/rustc_smir/context.rs
index e23f4289e98..4eefd0eb17c 100644
--- a/compiler/rustc_smir/src/rustc_smir/context.rs
+++ b/compiler/rustc_smir/src/rustc_smir/context.rs
@@ -160,7 +160,8 @@ impl<'tcx> Context for TablesWrapper<'tcx> {
     fn predicates_of(&self, def_id: stable_mir::DefId) -> stable_mir::ty::GenericPredicates {
         let mut tables = self.0.borrow_mut();
         let def_id = tables[def_id];
-        let GenericPredicates { parent, predicates } = tables.tcx.predicates_of(def_id);
+        let GenericPredicates { parent, predicates, effects_min_tys: _ } =
+            tables.tcx.predicates_of(def_id);
         stable_mir::ty::GenericPredicates {
             parent: parent.map(|did| tables.trait_def(did)),
             predicates: predicates
@@ -181,7 +182,8 @@ impl<'tcx> Context for TablesWrapper<'tcx> {
     ) -> stable_mir::ty::GenericPredicates {
         let mut tables = self.0.borrow_mut();
         let def_id = tables[def_id];
-        let GenericPredicates { parent, predicates } = tables.tcx.explicit_predicates_of(def_id);
+        let GenericPredicates { parent, predicates, effects_min_tys: _ } =
+            tables.tcx.explicit_predicates_of(def_id);
         stable_mir::ty::GenericPredicates {
             parent: parent.map(|did| tables.trait_def(did)),
             predicates: predicates
diff --git a/compiler/rustc_smir/src/rustc_smir/convert/ty.rs b/compiler/rustc_smir/src/rustc_smir/convert/ty.rs
index 74c3fcc9b9e..9382460d6d4 100644
--- a/compiler/rustc_smir/src/rustc_smir/convert/ty.rs
+++ b/compiler/rustc_smir/src/rustc_smir/convert/ty.rs
@@ -600,7 +600,7 @@ impl<'tcx> Stable<'tcx> for rustc_middle::ty::GenericParamDefKind {
             ty::GenericParamDefKind::Type { has_default, synthetic } => {
                 GenericParamDefKind::Type { has_default: *has_default, synthetic: *synthetic }
             }
-            ty::GenericParamDefKind::Const { has_default, is_host_effect: _ } => {
+            ty::GenericParamDefKind::Const { has_default, is_host_effect: _, synthetic: _ } => {
                 GenericParamDefKind::Const { has_default: *has_default }
             }
         }
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index 3b6147c4c0f..7da9211bcbf 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -194,6 +194,14 @@ symbols! {
         Display,
         DoubleEndedIterator,
         Duration,
+        EffectsCompat,
+        EffectsIntersection,
+        EffectsIntersectionOutput,
+        EffectsMaybe,
+        EffectsNoRuntime,
+        EffectsRuntime,
+        EffectsTyCompat,
+        Effects__,
         Encodable,
         Encoder,
         Enumerate,
@@ -1606,6 +1614,7 @@ symbols! {
         rustc_do_not_const_check,
         rustc_doc_primitive,
         rustc_dummy,
+        rustc_dump_def_parents,
         rustc_dump_item_bounds,
         rustc_dump_predicates,
         rustc_dump_user_args,
@@ -1658,6 +1667,7 @@ symbols! {
         rustc_reallocator,
         rustc_regions,
         rustc_reservation_impl,
+        rustc_runtime,
         rustc_safe_intrinsic,
         rustc_serialize,
         rustc_skip_during_method_dispatch,
diff --git a/compiler/rustc_trait_selection/Cargo.toml b/compiler/rustc_trait_selection/Cargo.toml
index 1f4fb57d996..f023a0eb53a 100644
--- a/compiler/rustc_trait_selection/Cargo.toml
+++ b/compiler/rustc_trait_selection/Cargo.toml
@@ -5,8 +5,6 @@ edition = "2021"
 
 [dependencies]
 # tidy-alphabetical-start
-bitflags = "2.4.1"
-derivative = "2.2.0"
 itertools = "0.12"
 rustc_ast = { path = "../rustc_ast" }
 rustc_ast_ir = { path = "../rustc_ast_ir" }
@@ -15,7 +13,6 @@ rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_errors = { path = "../rustc_errors" }
 rustc_fluent_macro = { path = "../rustc_fluent_macro" }
 rustc_hir = { path = "../rustc_hir" }
-rustc_index = { path = "../rustc_index" }
 rustc_infer = { path = "../rustc_infer" }
 rustc_macros = { path = "../rustc_macros" }
 rustc_middle = { path = "../rustc_middle" }
@@ -28,7 +25,6 @@ rustc_span = { path = "../rustc_span" }
 rustc_target = { path = "../rustc_target" }
 rustc_transmute = { path = "../rustc_transmute", features = ["rustc"] }
 rustc_type_ir = { path = "../rustc_type_ir" }
-rustc_type_ir_macros = { path = "../rustc_type_ir_macros" }
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
 tracing = "0.1"
 # tidy-alphabetical-end
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/infer_ctxt_ext.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/infer_ctxt_ext.rs
index 4b5b1d77b30..34da8e576ce 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/infer_ctxt_ext.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/infer_ctxt_ext.rs
@@ -88,7 +88,7 @@ impl<'tcx> InferCtxt<'tcx> {
         found_args: Vec<ArgKind>,
         is_closure: bool,
         closure_arg_span: Option<Span>,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'_> {
         let kind = if is_closure { "closure" } else { "function" };
 
         let args_str = |arguments: &[ArgKind], other: &[ArgKind]| {
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
index f4a026c0367..ccf86dbb1d0 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
@@ -241,8 +241,8 @@ pub fn suggest_restriction<'tcx, G: EmissionGuarantee>(
     }
 }
 
-#[extension(pub trait TypeErrCtxtExt<'tcx>)]
-impl<'tcx> TypeErrCtxt<'_, 'tcx> {
+#[extension(pub trait TypeErrCtxtExt<'a, 'tcx>)]
+impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
     fn suggest_restricting_param_bound(
         &self,
         err: &mut Diag<'_>,
@@ -1845,7 +1845,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
 
     fn point_at_returns_when_relevant(
         &self,
-        err: &mut Diag<'tcx>,
+        err: &mut Diag<'_>,
         obligation: &PredicateObligation<'tcx>,
     ) {
         match obligation.cause.code().peel_derives() {
@@ -1884,7 +1884,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         cause: &ObligationCauseCode<'tcx>,
         found_node: Option<Node<'_>>,
         param_env: ty::ParamEnv<'tcx>,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'a> {
         pub(crate) fn build_fn_sig_ty<'tcx>(
             infcx: &InferCtxt<'tcx>,
             trait_ref: ty::TraitRef<'tcx>,
@@ -2104,7 +2104,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
     fn note_conflicting_closure_bounds(
         &self,
         cause: &ObligationCauseCode<'tcx>,
-        err: &mut Diag<'tcx>,
+        err: &mut Diag<'_>,
     ) {
         // First, look for an `WhereClauseInExpr`, which means we can get
         // the uninstantiated predicate list of the called function. And check
@@ -4995,6 +4995,12 @@ fn point_at_assoc_type_restriction<G: EmissionGuarantee>(
     let ty::ClauseKind::Projection(proj) = clause else {
         return;
     };
+    // avoid ICEing since effects desugared associated types don't have names.
+    // this path should only be hit for `~const` on invalid places, so they
+    // will have an informative error already.
+    if tcx.is_effects_desugared_assoc_ty(proj.projection_term.def_id) {
+        return;
+    }
     let name = tcx.item_name(proj.projection_term.def_id);
     let mut predicates = generics.predicates.iter().peekable();
     let mut prev: Option<&hir::WhereBoundPredicate<'_>> = None;
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs
index d3096cf4b52..adf1076a7c9 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs
@@ -82,8 +82,8 @@ pub fn suggest_new_overflow_limit<'tcx, G: EmissionGuarantee>(
     ));
 }
 
-#[extension(pub trait TypeErrCtxtExt<'tcx>)]
-impl<'tcx> TypeErrCtxt<'_, 'tcx> {
+#[extension(pub trait TypeErrCtxtExt<'a, 'tcx>)]
+impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
     fn report_fulfillment_errors(
         &self,
         mut errors: Vec<FulfillmentError<'tcx>>,
@@ -228,7 +228,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         cause: OverflowCause<'tcx>,
         span: Span,
         suggest_increasing_limit: bool,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'a> {
         fn with_short_path<'tcx, T>(tcx: TyCtxt<'tcx>, value: T) -> String
         where
             T: fmt::Display + Print<'tcx, FmtPrinter<'tcx, 'tcx>>,
@@ -1101,7 +1101,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                 && let ty::FnPtr(sig) = by_ref_captures.kind()
                 && !sig.skip_binder().output().is_unit()
             {
-                let mut err = self.tcx.dcx().create_err(AsyncClosureNotFn {
+                let mut err = self.dcx().create_err(AsyncClosureNotFn {
                     span: self.tcx.def_span(closure_def_id),
                     kind: expected_kind.as_str(),
                 });
@@ -1351,7 +1351,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         &self,
         ty: Ty<'tcx>,
         obligation: &PredicateObligation<'tcx>,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'a> {
         let span = obligation.cause.span;
 
         let mut diag = match ty.kind() {
@@ -1445,8 +1445,8 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
     }
 }
 
-#[extension(pub(super) trait InferCtxtPrivExt<'tcx>)]
-impl<'tcx> TypeErrCtxt<'_, 'tcx> {
+#[extension(pub(super) trait InferCtxtPrivExt<'a, 'tcx>)]
+impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
     fn can_match_trait(
         &self,
         goal: ty::TraitPredicate<'tcx>,
@@ -2884,7 +2884,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
             self.suggest_unsized_bound_if_applicable(err, obligation);
             if let Some(span) = err.span.primary_span()
                 && let Some(mut diag) =
-                    self.tcx.dcx().steal_non_err(span, StashKey::AssociatedTypeSuggestion)
+                    self.dcx().steal_non_err(span, StashKey::AssociatedTypeSuggestion)
                 && let Ok(ref mut s1) = err.suggestions
                 && let Ok(ref mut s2) = diag.suggestions
             {
@@ -3379,7 +3379,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         found_kind: ty::ClosureKind,
         kind: ty::ClosureKind,
         trait_prefix: &'static str,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'a> {
         let closure_span = self.tcx.def_span(closure_def_id);
 
         let mut err = ClosureKindMismatch {
@@ -3422,7 +3422,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         found_trait_ref: ty::TraitRef<'tcx>,
         expected_trait_ref: ty::TraitRef<'tcx>,
         terr: TypeError<'tcx>,
-    ) -> Diag<'tcx> {
+    ) -> Diag<'a> {
         let self_ty = found_trait_ref.self_ty();
         let (cause, terr) = if let ty::Closure(def_id, _) = self_ty.kind() {
             (
@@ -3473,7 +3473,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         span: Span,
         found_trait_ref: ty::TraitRef<'tcx>,
         expected_trait_ref: ty::TraitRef<'tcx>,
-    ) -> Result<Diag<'tcx>, ErrorGuaranteed> {
+    ) -> Result<Diag<'a>, ErrorGuaranteed> {
         let found_trait_ref = self.resolve_vars_if_possible(found_trait_ref);
         let expected_trait_ref = self.resolve_vars_if_possible(expected_trait_ref);
 
@@ -3553,7 +3553,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                     })
                     .unwrap_or((found_span, None, found));
 
-                self.report_arg_count_mismatch(
+                self.infcx.report_arg_count_mismatch(
                     span,
                     closure_span,
                     expected,
@@ -3569,7 +3569,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         &self,
         obligation: &PredicateObligation<'tcx>,
         span: Span,
-    ) -> Result<Diag<'tcx>, ErrorGuaranteed> {
+    ) -> Result<Diag<'a>, ErrorGuaranteed> {
         if !self.tcx.features().generic_const_exprs {
             let guar = self
                 .dcx()
diff --git a/compiler/rustc_trait_selection/src/traits/object_safety.rs b/compiler/rustc_trait_selection/src/traits/object_safety.rs
index 4d10d33fa6e..f1611bd049d 100644
--- a/compiler/rustc_trait_selection/src/traits/object_safety.rs
+++ b/compiler/rustc_trait_selection/src/traits/object_safety.rs
@@ -187,7 +187,7 @@ fn predicates_reference_self(
 ) -> SmallVec<[Span; 1]> {
     let trait_ref = ty::Binder::dummy(ty::TraitRef::identity(tcx, trait_def_id));
     let predicates = if supertraits_only {
-        tcx.super_predicates_of(trait_def_id)
+        tcx.explicit_super_predicates_of(trait_def_id)
     } else {
         tcx.predicates_of(trait_def_id)
     };
@@ -256,7 +256,7 @@ fn super_predicates_have_non_lifetime_binders(
     if !tcx.features().non_lifetime_binders {
         return SmallVec::new();
     }
-    tcx.super_predicates_of(trait_def_id)
+    tcx.explicit_super_predicates_of(trait_def_id)
         .predicates
         .iter()
         .filter_map(|(pred, span)| pred.has_non_region_bound_vars().then_some(*span))
diff --git a/compiler/rustc_trait_selection/src/traits/select/confirmation.rs b/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
index 8c5dc88184c..9508a3e8e15 100644
--- a/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
@@ -574,7 +574,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         // Check supertraits hold. This is so that their associated type bounds
         // will be checked in the code below.
         for super_trait in tcx
-            .super_predicates_of(trait_predicate.def_id())
+            .explicit_super_predicates_of(trait_predicate.def_id())
             .instantiate(tcx, trait_predicate.trait_ref.args)
             .predicates
             .into_iter()
diff --git a/compiler/rustc_trait_selection/src/traits/util.rs b/compiler/rustc_trait_selection/src/traits/util.rs
index f132e36468a..951af4b0920 100644
--- a/compiler/rustc_trait_selection/src/traits/util.rs
+++ b/compiler/rustc_trait_selection/src/traits/util.rs
@@ -128,7 +128,7 @@ impl<'tcx> TraitAliasExpander<'tcx> {
         }
 
         // Get components of trait alias.
-        let predicates = tcx.super_predicates_of(trait_ref.def_id());
+        let predicates = tcx.explicit_super_predicates_of(trait_ref.def_id());
         debug!(?predicates);
 
         let items = predicates.predicates.iter().rev().filter_map(|(pred, span)| {
diff --git a/compiler/rustc_trait_selection/src/traits/vtable.rs b/compiler/rustc_trait_selection/src/traits/vtable.rs
index 017b0a45d1f..e54ced85dee 100644
--- a/compiler/rustc_trait_selection/src/traits/vtable.rs
+++ b/compiler/rustc_trait_selection/src/traits/vtable.rs
@@ -117,7 +117,7 @@ fn prepare_vtable_segments_inner<'tcx, T>(
             let &(inner_most_trait_ref, _, _) = stack.last().unwrap();
 
             let mut direct_super_traits_iter = tcx
-                .super_predicates_of(inner_most_trait_ref.def_id())
+                .explicit_super_predicates_of(inner_most_trait_ref.def_id())
                 .predicates
                 .into_iter()
                 .filter_map(move |(pred, _)| {
diff --git a/compiler/rustc_ty_utils/src/assoc.rs b/compiler/rustc_ty_utils/src/assoc.rs
index 4395eb57cd6..6726db8bb54 100644
--- a/compiler/rustc_ty_utils/src/assoc.rs
+++ b/compiler/rustc_ty_utils/src/assoc.rs
@@ -4,8 +4,9 @@ use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{DefId, DefIdMap, LocalDefId};
 use rustc_hir::intravisit::{self, Visitor};
 use rustc_middle::query::Providers;
-use rustc_middle::ty::{self, ImplTraitInTraitData, TyCtxt};
+use rustc_middle::ty::{self, ImplTraitInTraitData, Ty, TyCtxt};
 use rustc_middle::{bug, span_bug};
+use rustc_span::sym;
 use rustc_span::symbol::kw;
 
 pub(crate) fn provide(providers: &mut Providers) {
@@ -14,6 +15,7 @@ pub(crate) fn provide(providers: &mut Providers) {
         associated_item_def_ids,
         associated_items,
         associated_types_for_impl_traits_in_associated_fn,
+        associated_type_for_effects,
         associated_type_for_impl_trait_in_trait,
         impl_item_implementor_ids,
         ..*providers
@@ -44,7 +46,8 @@ fn associated_item_def_ids(tcx: TyCtxt<'_>, def_id: LocalDefId) -> &[DefId] {
                                 )
                             })
                             .copied(),
-                    ),
+                    )
+                    .chain(tcx.associated_type_for_effects(def_id)),
             )
         }
         hir::ItemKind::Impl(impl_) => {
@@ -70,7 +73,8 @@ fn associated_item_def_ids(tcx: TyCtxt<'_>, def_id: LocalDefId) -> &[DefId] {
                                 )
                             })
                             .copied()
-                    })),
+                    }))
+                    .chain(tcx.associated_type_for_effects(def_id)),
             )
         }
         _ => span_bug!(item.span, "associated_item_def_ids: not impl or trait"),
@@ -143,6 +147,7 @@ fn associated_item_from_trait_item_ref(trait_item_ref: &hir::TraitItemRef) -> ty
         container: ty::TraitContainer,
         fn_has_self_parameter: has_self,
         opt_rpitit_info: None,
+        is_effects_desugaring: false,
     }
 }
 
@@ -162,9 +167,138 @@ fn associated_item_from_impl_item_ref(impl_item_ref: &hir::ImplItemRef) -> ty::A
         container: ty::ImplContainer,
         fn_has_self_parameter: has_self,
         opt_rpitit_info: None,
+        is_effects_desugaring: false,
     }
 }
 
+/// Given an `def_id` of a trait or a trait impl:
+///
+/// If `def_id` is a trait that has `#[const_trait]`, then it synthesizes
+/// a new def id corresponding to a new associated type for the effects.
+///
+/// If `def_id` is an impl, then synthesize the associated type according
+/// to the constness of the impl.
+fn associated_type_for_effects(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Option<DefId> {
+    // don't synthesize the associated type even if the user has written `const_trait`
+    // if the effects feature is disabled.
+    if !tcx.features().effects {
+        return None;
+    }
+    let (feed, parent_did) = match tcx.def_kind(def_id) {
+        DefKind::Trait => {
+            let trait_def_id = def_id;
+            let attr = tcx.get_attr(def_id, sym::const_trait)?;
+
+            let span = attr.span;
+            let trait_assoc_ty = tcx.at(span).create_def(trait_def_id, kw::Empty, DefKind::AssocTy);
+
+            let local_def_id = trait_assoc_ty.def_id();
+            let def_id = local_def_id.to_def_id();
+
+            // Copy span of the attribute.
+            trait_assoc_ty.def_ident_span(Some(span));
+
+            trait_assoc_ty.associated_item(ty::AssocItem {
+                name: kw::Empty,
+                kind: ty::AssocKind::Type,
+                def_id,
+                trait_item_def_id: None,
+                container: ty::TraitContainer,
+                fn_has_self_parameter: false,
+                opt_rpitit_info: None,
+                is_effects_desugaring: true,
+            });
+
+            // No default type
+            trait_assoc_ty.defaultness(hir::Defaultness::Default { has_value: false });
+
+            trait_assoc_ty.is_type_alias_impl_trait(false);
+
+            (trait_assoc_ty, trait_def_id)
+        }
+        DefKind::Impl { .. } => {
+            let impl_def_id = def_id;
+            let trait_id = tcx.trait_id_of_impl(def_id.to_def_id())?;
+
+            // first get the DefId of the assoc type on the trait, if there is not,
+            // then we don't need to generate it on the impl.
+            let trait_assoc_id = tcx.associated_type_for_effects(trait_id)?;
+
+            // FIXME(effects): span
+            let span = tcx.def_ident_span(def_id).unwrap();
+
+            let impl_assoc_ty = tcx.at(span).create_def(def_id, kw::Empty, DefKind::AssocTy);
+
+            let local_def_id = impl_assoc_ty.def_id();
+            let def_id = local_def_id.to_def_id();
+
+            impl_assoc_ty.def_ident_span(Some(span));
+
+            impl_assoc_ty.associated_item(ty::AssocItem {
+                name: kw::Empty,
+                kind: ty::AssocKind::Type,
+                def_id,
+                trait_item_def_id: Some(trait_assoc_id),
+                container: ty::ImplContainer,
+                fn_has_self_parameter: false,
+                opt_rpitit_info: None,
+                is_effects_desugaring: true,
+            });
+
+            // no default value.
+            impl_assoc_ty.defaultness(hir::Defaultness::Final);
+
+            // set the type of the associated type! If this is a const impl,
+            // we set to Maybe, otherwise we set to `Runtime`.
+            let type_def_id = if tcx.is_const_trait_impl_raw(impl_def_id.to_def_id()) {
+                tcx.require_lang_item(hir::LangItem::EffectsMaybe, Some(span))
+            } else {
+                tcx.require_lang_item(hir::LangItem::EffectsRuntime, Some(span))
+            };
+            // FIXME(effects): make impls use `Min` for their effect types
+            impl_assoc_ty.type_of(ty::EarlyBinder::bind(Ty::new_adt(
+                tcx,
+                tcx.adt_def(type_def_id),
+                ty::GenericArgs::empty(),
+            )));
+
+            (impl_assoc_ty, impl_def_id)
+        }
+        def_kind => bug!(
+            "associated_type_for_effects: {:?} should be Trait or Impl but is {:?}",
+            def_id,
+            def_kind
+        ),
+    };
+
+    feed.feed_hir();
+
+    // visibility is public.
+    feed.visibility(ty::Visibility::Public);
+
+    // Copy generics_of of the trait/impl, making the trait/impl as parent.
+    feed.generics_of({
+        let parent_generics = tcx.generics_of(parent_did);
+        let parent_count = parent_generics.parent_count + parent_generics.own_params.len();
+
+        ty::Generics {
+            parent: Some(parent_did.to_def_id()),
+            parent_count,
+            own_params: vec![],
+            param_def_id_to_index: parent_generics.param_def_id_to_index.clone(),
+            has_self: false,
+            has_late_bound_regions: None,
+            host_effect_index: parent_generics.host_effect_index,
+        }
+    });
+    feed.explicit_item_super_predicates(ty::EarlyBinder::bind(&[]));
+
+    // There are no inferred outlives for the synthesized associated type.
+    feed.inferred_outlives_of(&[]);
+
+    Some(feed.def_id().to_def_id())
+}
+
 /// Given an `fn_def_id` of a trait or a trait implementation:
 ///
 /// if `fn_def_id` is a function defined inside a trait, then it synthesizes
@@ -275,6 +409,7 @@ fn associated_type_for_impl_trait_in_trait(
             fn_def_id: fn_def_id.to_def_id(),
             opaque_def_id: opaque_ty_def_id.to_def_id(),
         }),
+        is_effects_desugaring: false,
     });
 
     // Copy visility of the containing function.
@@ -326,6 +461,7 @@ fn associated_type_for_impl_trait_in_impl(
         container: ty::ImplContainer,
         fn_has_self_parameter: false,
         opt_rpitit_info: Some(ImplTraitInTraitData::Impl { fn_def_id: impl_fn_def_id.to_def_id() }),
+        is_effects_desugaring: false,
     });
 
     // Copy visility of the containing function.
diff --git a/compiler/rustc_type_ir/src/effects.rs b/compiler/rustc_type_ir/src/effects.rs
new file mode 100644
index 00000000000..f7942f2f982
--- /dev/null
+++ b/compiler/rustc_type_ir/src/effects.rs
@@ -0,0 +1,59 @@
+use crate::inherent::{AdtDef, IntoKind, Ty};
+use crate::lang_items::TraitSolverLangItem::{EffectsMaybe, EffectsNoRuntime, EffectsRuntime};
+use crate::Interner;
+
+#[derive(Clone, Copy, PartialEq, Eq)]
+pub enum EffectKind {
+    Maybe,
+    Runtime,
+    NoRuntime,
+}
+
+impl EffectKind {
+    pub fn try_from_def_id<I: Interner>(tcx: I, def_id: I::DefId) -> Option<EffectKind> {
+        if tcx.is_lang_item(def_id, EffectsMaybe) {
+            Some(EffectKind::Maybe)
+        } else if tcx.is_lang_item(def_id, EffectsRuntime) {
+            Some(EffectKind::Runtime)
+        } else if tcx.is_lang_item(def_id, EffectsNoRuntime) {
+            Some(EffectKind::NoRuntime)
+        } else {
+            None
+        }
+    }
+
+    pub fn to_def_id<I: Interner>(self, tcx: I) -> I::DefId {
+        let lang_item = match self {
+            EffectKind::Maybe => EffectsMaybe,
+            EffectKind::NoRuntime => EffectsNoRuntime,
+            EffectKind::Runtime => EffectsRuntime,
+        };
+
+        tcx.require_lang_item(lang_item)
+    }
+
+    pub fn try_from_ty<I: Interner>(tcx: I, ty: I::Ty) -> Option<EffectKind> {
+        if let crate::Adt(def, _) = ty.kind() {
+            Self::try_from_def_id(tcx, def.def_id())
+        } else {
+            None
+        }
+    }
+
+    pub fn to_ty<I: Interner>(self, tcx: I) -> I::Ty {
+        I::Ty::new_adt(tcx, tcx.adt_def(self.to_def_id(tcx)), Default::default())
+    }
+
+    /// Returns an intersection between two effect kinds. If one effect kind
+    /// is more permissive than the other (e.g. `Maybe` vs `Runtime`), this
+    /// returns the less permissive effect kind (`Runtime`).
+    pub fn intersection(a: Self, b: Self) -> Option<Self> {
+        use EffectKind::*;
+        match (a, b) {
+            (Maybe, x) | (x, Maybe) => Some(x),
+            (Runtime, Runtime) => Some(Runtime),
+            (NoRuntime, NoRuntime) => Some(NoRuntime),
+            (Runtime, NoRuntime) | (NoRuntime, Runtime) => None,
+        }
+    }
+}
diff --git a/compiler/rustc_type_ir/src/interner.rs b/compiler/rustc_type_ir/src/interner.rs
index b89ea30fc34..6665158c7cd 100644
--- a/compiler/rustc_type_ir/src/interner.rs
+++ b/compiler/rustc_type_ir/src/interner.rs
@@ -209,8 +209,7 @@ pub trait Interner:
         def_id: Self::DefId,
     ) -> ty::EarlyBinder<Self, impl IntoIterator<Item = Self::Clause>>;
 
-    // FIXME: Rename this so it's obvious it's only *immediate* super predicates.
-    fn super_predicates_of(
+    fn explicit_super_predicates_of(
         self,
         def_id: Self::DefId,
     ) -> ty::EarlyBinder<Self, impl IntoIterator<Item = Self::Clause>>;
diff --git a/compiler/rustc_type_ir/src/lang_items.rs b/compiler/rustc_type_ir/src/lang_items.rs
index cf5ec1ab3fe..cf00c37caa2 100644
--- a/compiler/rustc_type_ir/src/lang_items.rs
+++ b/compiler/rustc_type_ir/src/lang_items.rs
@@ -17,6 +17,11 @@ pub enum TraitSolverLangItem {
     Destruct,
     DiscriminantKind,
     DynMetadata,
+    EffectsIntersection,
+    EffectsIntersectionOutput,
+    EffectsMaybe,
+    EffectsNoRuntime,
+    EffectsRuntime,
     FnPtrTrait,
     FusedIterator,
     Future,
diff --git a/compiler/rustc_type_ir/src/lib.rs b/compiler/rustc_type_ir/src/lib.rs
index 9b8ca5efdda..d7442e7c89c 100644
--- a/compiler/rustc_type_ir/src/lib.rs
+++ b/compiler/rustc_type_ir/src/lib.rs
@@ -35,6 +35,7 @@ mod macros;
 mod binder;
 mod canonical;
 mod const_kind;
+mod effects;
 mod flags;
 mod generic_arg;
 mod interner;
@@ -51,6 +52,7 @@ pub use canonical::*;
 #[cfg(feature = "nightly")]
 pub use codec::*;
 pub use const_kind::*;
+pub use effects::*;
 pub use flags::*;
 pub use generic_arg::*;
 pub use interner::*;