Auto merge of #2731 - RalfJung:rustup, r=RalfJung

Rustup

16 files changed, 99 insertions, 884 deletions

diff --git a/compiler/rustc_hir_analysis/src/astconv/mod.rs b/compiler/rustc_hir_analysis/src/astconv/mod.rs
index 66906b331da..71f26eb60c9 100644
--- a/compiler/rustc_hir_analysis/src/astconv/mod.rs
+++ b/compiler/rustc_hir_analysis/src/astconv/mod.rs
@@ -680,7 +680,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         let assoc_bindings = self.create_assoc_bindings_for_generic_args(args);
 
         let poly_trait_ref =
-            ty::Binder::bind_with_vars(ty::TraitRef::new(trait_def_id, substs), bound_vars);
+            ty::Binder::bind_with_vars(tcx.mk_trait_ref(trait_def_id, substs), bound_vars);
 
         debug!(?poly_trait_ref, ?assoc_bindings);
         bounds.trait_bounds.push((poly_trait_ref, span, constness));
@@ -813,7 +813,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         if let Some(b) = trait_segment.args().bindings.first() {
             Self::prohibit_assoc_ty_binding(self.tcx(), b.span);
         }
-        ty::TraitRef::new(trait_def_id, substs)
+        self.tcx().mk_trait_ref(trait_def_id, substs)
     }
 
     #[instrument(level = "debug", skip(self, span))]
@@ -1146,10 +1146,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
 
             debug!(?substs_trait_ref_and_assoc_item);
 
-            ty::ProjectionTy {
-                item_def_id: assoc_item.def_id,
-                substs: substs_trait_ref_and_assoc_item,
-            }
+            self.tcx().mk_alias_ty(assoc_item.def_id, substs_trait_ref_and_assoc_item)
         });
 
         if !speculative {
@@ -1195,7 +1192,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                 // the "projection predicate" for:
                 //
                 // `<T as Iterator>::Item = u32`
-                let assoc_item_def_id = projection_ty.skip_binder().item_def_id;
+                let assoc_item_def_id = projection_ty.skip_binder().def_id;
                 let def_kind = tcx.def_kind(assoc_item_def_id);
                 match (def_kind, term.unpack()) {
                     (hir::def::DefKind::AssocTy, ty::TermKind::Ty(_))
@@ -1244,7 +1241,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                 //
                 // Calling `skip_binder` is okay, because `add_bounds` expects the `param_ty`
                 // parameter to have a skipped binder.
-                let param_ty = tcx.mk_ty(ty::Projection(projection_ty.skip_binder()));
+                let param_ty = tcx.mk_ty(ty::Alias(ty::Projection, projection_ty.skip_binder()));
                 self.add_bounds(param_ty, ast_bounds.iter(), bounds, candidate.bound_vars());
             }
         }
diff --git a/compiler/rustc_hir_analysis/src/check/check.rs b/compiler/rustc_hir_analysis/src/check/check.rs
index fc0ca62090d..aa01feb3a1e 100644
--- a/compiler/rustc_hir_analysis/src/check/check.rs
+++ b/compiler/rustc_hir_analysis/src/check/check.rs
@@ -570,7 +570,7 @@ fn check_item_type<'tcx>(tcx: TyCtxt<'tcx>, id: hir::ItemId) {
                             assoc_item,
                             assoc_item,
                             default.span,
-                            ty::TraitRef { def_id: it.owner_id.to_def_id(), substs: trait_substs },
+                            tcx.mk_trait_ref(it.owner_id.to_def_id(), trait_substs),
                         );
                     }
                     _ => {}
@@ -1440,7 +1440,7 @@ fn opaque_type_cycle_error(tcx: TyCtxt<'_>, def_id: LocalDefId, span: Span) -> E
                 impl<'tcx> ty::visit::TypeVisitor<'tcx> for OpaqueTypeCollector {
                     fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
                         match *t.kind() {
-                            ty::Opaque(def, _) => {
+                            ty::Alias(ty::Opaque, ty::AliasTy { def_id: def, .. }) => {
                                 self.0.push(def);
                                 ControlFlow::CONTINUE
                             }
diff --git a/compiler/rustc_hir_analysis/src/check/compare_method.rs b/compiler/rustc_hir_analysis/src/check/compare_method.rs
index 1d6f9b29176..6b9ce9a4599 100644
--- a/compiler/rustc_hir_analysis/src/check/compare_method.rs
+++ b/compiler/rustc_hir_analysis/src/check/compare_method.rs
@@ -67,6 +67,10 @@ pub(crate) fn compare_impl_method<'tcx>(
         return;
     }
 
+    if let Err(_) = compare_asyncness(tcx, impl_m, impl_m_span, trait_m, trait_item_span) {
+        return;
+    }
+
     if let Err(_) = compare_predicate_entailment(tcx, impl_m, impl_m_span, trait_m, impl_trait_ref)
     {
         return;
@@ -323,6 +327,34 @@ fn compare_predicate_entailment<'tcx>(
     Ok(())
 }
 
+fn compare_asyncness<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    impl_m: &ty::AssocItem,
+    impl_m_span: Span,
+    trait_m: &ty::AssocItem,
+    trait_item_span: Option<Span>,
+) -> Result<(), ErrorGuaranteed> {
+    if tcx.asyncness(trait_m.def_id) == hir::IsAsync::Async {
+        match tcx.fn_sig(impl_m.def_id).skip_binder().output().kind() {
+            ty::Alias(ty::Opaque, ..) => {
+                // allow both `async fn foo()` and `fn foo() -> impl Future`
+            }
+            ty::Error(rustc_errors::ErrorGuaranteed { .. }) => {
+                // We don't know if it's ok, but at least it's already an error.
+            }
+            _ => {
+                return Err(tcx.sess.emit_err(crate::errors::AsyncTraitImplShouldBeAsync {
+                    span: impl_m_span,
+                    method_name: trait_m.name,
+                    trait_item_span,
+                }));
+            }
+        };
+    }
+
+    Ok(())
+}
+
 #[instrument(skip(tcx), level = "debug", ret)]
 pub fn collect_trait_impl_trait_tys<'tcx>(
     tcx: TyCtxt<'tcx>,
@@ -571,10 +603,10 @@ impl<'tcx> TypeFolder<'tcx> for ImplTraitInTraitCollector<'_, 'tcx> {
     }
 
     fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
-        if let ty::Projection(proj) = ty.kind()
-            && self.tcx().def_kind(proj.item_def_id) == DefKind::ImplTraitPlaceholder
+        if let ty::Alias(ty::Projection, proj) = ty.kind()
+            && self.tcx().def_kind(proj.def_id) == DefKind::ImplTraitPlaceholder
         {
-            if let Some((ty, _)) = self.types.get(&proj.item_def_id) {
+            if let Some((ty, _)) = self.types.get(&proj.def_id) {
                 return *ty;
             }
             //FIXME(RPITIT): Deny nested RPITIT in substs too
@@ -586,9 +618,9 @@ impl<'tcx> TypeFolder<'tcx> for ImplTraitInTraitCollector<'_, 'tcx> {
                 span: self.span,
                 kind: TypeVariableOriginKind::MiscVariable,
             });
-            self.types.insert(proj.item_def_id, (infer_ty, proj.substs));
+            self.types.insert(proj.def_id, (infer_ty, proj.substs));
             // Recurse into bounds
-            for (pred, pred_span) in self.tcx().bound_explicit_item_bounds(proj.item_def_id).subst_iter_copied(self.tcx(), proj.substs) {
+            for (pred, pred_span) in self.tcx().bound_explicit_item_bounds(proj.def_id).subst_iter_copied(self.tcx(), proj.substs) {
                 let pred = pred.fold_with(self);
                 let pred = self.ocx.normalize(
                     &ObligationCause::misc(self.span, self.body_id),
@@ -601,7 +633,7 @@ impl<'tcx> TypeFolder<'tcx> for ImplTraitInTraitCollector<'_, 'tcx> {
                     ObligationCause::new(
                         self.span,
                         self.body_id,
-                        ObligationCauseCode::BindingObligation(proj.item_def_id, pred_span),
+                        ObligationCauseCode::BindingObligation(proj.def_id, pred_span),
                     ),
                     self.param_env,
                     pred,
@@ -1734,8 +1766,8 @@ pub fn check_type_bounds<'tcx>(
     let normalize_param_env = {
         let mut predicates = param_env.caller_bounds().iter().collect::<Vec<_>>();
         match impl_ty_value.kind() {
-            ty::Projection(proj)
-                if proj.item_def_id == trait_ty.def_id && proj.substs == rebased_substs =>
+            ty::Alias(ty::Projection, proj)
+                if proj.def_id == trait_ty.def_id && proj.substs == rebased_substs =>
             {
                 // Don't include this predicate if the projected type is
                 // exactly the same as the projection. This can occur in
@@ -1746,10 +1778,7 @@ pub fn check_type_bounds<'tcx>(
             _ => predicates.push(
                 ty::Binder::bind_with_vars(
                     ty::ProjectionPredicate {
-                        projection_ty: ty::ProjectionTy {
-                            item_def_id: trait_ty.def_id,
-                            substs: rebased_substs,
-                        },
+                        projection_ty: tcx.mk_alias_ty(trait_ty.def_id, rebased_substs),
                         term: impl_ty_value.into(),
                     },
                     bound_vars,
diff --git a/compiler/rustc_hir_analysis/src/check/mod.rs b/compiler/rustc_hir_analysis/src/check/mod.rs
index 29255472a25..57f0cae12bb 100644
--- a/compiler/rustc_hir_analysis/src/check/mod.rs
+++ b/compiler/rustc_hir_analysis/src/check/mod.rs
@@ -352,11 +352,7 @@ fn bounds_from_generic_predicates<'tcx>(
         // insert the associated types where they correspond, but for now let's be "lazy" and
         // propose this instead of the following valid resugaring:
         // `T: Trait, Trait::Assoc = K` → `T: Trait<Assoc = K>`
-        where_clauses.push(format!(
-            "{} = {}",
-            tcx.def_path_str(p.projection_ty.item_def_id),
-            p.term,
-        ));
+        where_clauses.push(format!("{} = {}", tcx.def_path_str(p.projection_ty.def_id), p.term));
     }
     let where_clauses = if where_clauses.is_empty() {
         String::new()
diff --git a/compiler/rustc_hir_analysis/src/check/wfcheck.rs b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
index b065ace6bf5..94d333c336e 100644
--- a/compiler/rustc_hir_analysis/src/check/wfcheck.rs
+++ b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
@@ -31,7 +31,6 @@ use rustc_trait_selection::traits::{
 };
 
 use std::cell::LazyCell;
-use std::convert::TryInto;
 use std::iter;
 use std::ops::{ControlFlow, Deref};
 
@@ -760,7 +759,7 @@ impl<'tcx> TypeVisitor<'tcx> for GATSubstCollector<'tcx> {
 
     fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
         match t.kind() {
-            ty::Projection(p) if p.item_def_id == self.gat => {
+            ty::Alias(ty::Projection, p) if p.def_id == self.gat => {
                 for (idx, subst) in p.substs.iter().enumerate() {
                     match subst.unpack() {
                         GenericArgKind::Lifetime(lt) if !lt.is_late_bound() => {
@@ -1593,12 +1592,12 @@ fn check_return_position_impl_trait_in_trait_bounds<'tcx>(
     {
         for arg in fn_output.walk() {
             if let ty::GenericArgKind::Type(ty) = arg.unpack()
-                && let ty::Projection(proj) = ty.kind()
-                && tcx.def_kind(proj.item_def_id) == DefKind::ImplTraitPlaceholder
-                && tcx.impl_trait_in_trait_parent(proj.item_def_id) == fn_def_id.to_def_id()
+                && let ty::Alias(ty::Projection, proj) = ty.kind()
+                && tcx.def_kind(proj.def_id) == DefKind::ImplTraitPlaceholder
+                && tcx.impl_trait_in_trait_parent(proj.def_id) == fn_def_id.to_def_id()
             {
-                let span = tcx.def_span(proj.item_def_id);
-                let bounds = wfcx.tcx().explicit_item_bounds(proj.item_def_id);
+                let span = tcx.def_span(proj.def_id);
+                let bounds = wfcx.tcx().explicit_item_bounds(proj.def_id);
                 let wf_obligations = bounds.iter().flat_map(|&(bound, bound_span)| {
                     let bound = ty::EarlyBinder(bound).subst(tcx, proj.substs);
                     let normalized_bound = wfcx.normalize(span, None, bound);
diff --git a/compiler/rustc_hir_analysis/src/coherence/inherent_impls.rs b/compiler/rustc_hir_analysis/src/coherence/inherent_impls.rs
index 2890c149b3a..6469f389bf9 100644
--- a/compiler/rustc_hir_analysis/src/coherence/inherent_impls.rs
+++ b/compiler/rustc_hir_analysis/src/coherence/inherent_impls.rs
@@ -223,7 +223,7 @@ impl<'tcx> InherentCollect<'tcx> {
             | ty::Tuple(..) => {
                 self.check_primitive_impl(item.owner_id.def_id, self_ty, items, ty.span)
             }
-            ty::Projection(..) | ty::Opaque(..) | ty::Param(_) => {
+            ty::Alias(..) | ty::Param(_) => {
                 let mut err = struct_span_err!(
                     self.tcx.sess,
                     ty.span,
diff --git a/compiler/rustc_hir_analysis/src/collect.rs b/compiler/rustc_hir_analysis/src/collect.rs
index 72288e5bc76..0c4649cea14 100644
--- a/compiler/rustc_hir_analysis/src/collect.rs
+++ b/compiler/rustc_hir_analysis/src/collect.rs
@@ -17,28 +17,20 @@
 use crate::astconv::AstConv;
 use crate::check::intrinsic::intrinsic_operation_unsafety;
 use crate::errors;
-use rustc_ast as ast;
-use rustc_ast::{MetaItemKind, NestedMetaItem};
-use rustc_attr::{list_contains_name, InlineAttr, InstructionSetAttr, OptimizeAttr};
 use rustc_data_structures::captures::Captures;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder, ErrorGuaranteed, StashKey};
 use rustc_hir as hir;
-use rustc_hir::def_id::{DefId, LocalDefId, LOCAL_CRATE};
+use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::intravisit::{self, Visitor};
-use rustc_hir::weak_lang_items::WEAK_LANG_ITEMS;
-use rustc_hir::{lang_items, GenericParamKind, LangItem, Node};
+use rustc_hir::{GenericParamKind, Node};
 use rustc_middle::hir::nested_filter;
-use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
-use rustc_middle::mir::mono::Linkage;
 use rustc_middle::ty::query::Providers;
 use rustc_middle::ty::util::{Discr, IntTypeExt};
-use rustc_middle::ty::{self, AdtKind, Const, DefIdTree, IsSuggestable, ToPredicate, Ty, TyCtxt};
-use rustc_session::lint;
-use rustc_session::parse::feature_err;
+use rustc_middle::ty::{self, AdtKind, Const, IsSuggestable, ToPredicate, Ty, TyCtxt};
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
 use rustc_span::Span;
-use rustc_target::spec::{abi, SanitizerSet};
+use rustc_target::spec::abi;
 use rustc_trait_selection::traits::error_reporting::suggestions::NextTypeParamName;
 use std::iter;
 
@@ -78,10 +70,7 @@ pub fn provide(providers: &mut Providers) {
         impl_polarity,
         is_foreign_item,
         generator_kind,
-        codegen_fn_attrs,
-        asm_target_features,
         collect_mod_item_types,
-        should_inherit_track_caller,
         ..*providers
     };
 }
@@ -500,7 +489,7 @@ impl<'tcx> AstConv<'tcx> for ItemCtxt<'tcx> {
                         format!(
                             "{}::",
                             // Erase named lt, we want `<A as B<'_>::C`, not `<A as B<'a>::C`.
-                            self.tcx.anonymize_late_bound_regions(poly_trait_ref).skip_binder(),
+                            self.tcx.anonymize_bound_vars(poly_trait_ref).skip_binder(),
                         ),
                         Applicability::MaybeIncorrect,
                     );
@@ -1455,797 +1444,3 @@ fn generator_kind(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::GeneratorKind>
         _ => bug!("generator_kind applied to non-local def-id {:?}", def_id),
     }
 }
-
-fn from_target_feature(
-    tcx: TyCtxt<'_>,
-    attr: &ast::Attribute,
-    supported_target_features: &FxHashMap<String, Option<Symbol>>,
-    target_features: &mut Vec<Symbol>,
-) {
-    let Some(list) = attr.meta_item_list() else { return };
-    let bad_item = |span| {
-        let msg = "malformed `target_feature` attribute input";
-        let code = "enable = \"..\"";
-        tcx.sess
-            .struct_span_err(span, msg)
-            .span_suggestion(span, "must be of the form", code, Applicability::HasPlaceholders)
-            .emit();
-    };
-    let rust_features = tcx.features();
-    for item in list {
-        // Only `enable = ...` is accepted in the meta-item list.
-        if !item.has_name(sym::enable) {
-            bad_item(item.span());
-            continue;
-        }
-
-        // Must be of the form `enable = "..."` (a string).
-        let Some(value) = item.value_str() else {
-            bad_item(item.span());
-            continue;
-        };
-
-        // We allow comma separation to enable multiple features.
-        target_features.extend(value.as_str().split(',').filter_map(|feature| {
-            let Some(feature_gate) = supported_target_features.get(feature) else {
-                let msg =
-                    format!("the feature named `{}` is not valid for this target", feature);
-                let mut err = tcx.sess.struct_span_err(item.span(), &msg);
-                err.span_label(
-                    item.span(),
-                    format!("`{}` is not valid for this target", feature),
-                );
-                if let Some(stripped) = feature.strip_prefix('+') {
-                    let valid = supported_target_features.contains_key(stripped);
-                    if valid {
-                        err.help("consider removing the leading `+` in the feature name");
-                    }
-                }
-                err.emit();
-                return None;
-            };
-
-            // Only allow features whose feature gates have been enabled.
-            let allowed = match feature_gate.as_ref().copied() {
-                Some(sym::arm_target_feature) => rust_features.arm_target_feature,
-                Some(sym::hexagon_target_feature) => rust_features.hexagon_target_feature,
-                Some(sym::powerpc_target_feature) => rust_features.powerpc_target_feature,
-                Some(sym::mips_target_feature) => rust_features.mips_target_feature,
-                Some(sym::riscv_target_feature) => rust_features.riscv_target_feature,
-                Some(sym::avx512_target_feature) => rust_features.avx512_target_feature,
-                Some(sym::sse4a_target_feature) => rust_features.sse4a_target_feature,
-                Some(sym::tbm_target_feature) => rust_features.tbm_target_feature,
-                Some(sym::wasm_target_feature) => rust_features.wasm_target_feature,
-                Some(sym::cmpxchg16b_target_feature) => rust_features.cmpxchg16b_target_feature,
-                Some(sym::movbe_target_feature) => rust_features.movbe_target_feature,
-                Some(sym::rtm_target_feature) => rust_features.rtm_target_feature,
-                Some(sym::f16c_target_feature) => rust_features.f16c_target_feature,
-                Some(sym::ermsb_target_feature) => rust_features.ermsb_target_feature,
-                Some(sym::bpf_target_feature) => rust_features.bpf_target_feature,
-                Some(sym::aarch64_ver_target_feature) => rust_features.aarch64_ver_target_feature,
-                Some(name) => bug!("unknown target feature gate {}", name),
-                None => true,
-            };
-            if !allowed {
-                feature_err(
-                    &tcx.sess.parse_sess,
-                    feature_gate.unwrap(),
-                    item.span(),
-                    &format!("the target feature `{}` is currently unstable", feature),
-                )
-                .emit();
-            }
-            Some(Symbol::intern(feature))
-        }));
-    }
-}
-
-fn linkage_by_name(tcx: TyCtxt<'_>, def_id: LocalDefId, name: &str) -> Linkage {
-    use rustc_middle::mir::mono::Linkage::*;
-
-    // Use the names from src/llvm/docs/LangRef.rst here. Most types are only
-    // applicable to variable declarations and may not really make sense for
-    // Rust code in the first place but allow them anyway and trust that the
-    // user knows what they're doing. Who knows, unanticipated use cases may pop
-    // up in the future.
-    //
-    // ghost, dllimport, dllexport and linkonce_odr_autohide are not supported
-    // and don't have to be, LLVM treats them as no-ops.
-    match name {
-        "appending" => Appending,
-        "available_externally" => AvailableExternally,
-        "common" => Common,
-        "extern_weak" => ExternalWeak,
-        "external" => External,
-        "internal" => Internal,
-        "linkonce" => LinkOnceAny,
-        "linkonce_odr" => LinkOnceODR,
-        "private" => Private,
-        "weak" => WeakAny,
-        "weak_odr" => WeakODR,
-        _ => tcx.sess.span_fatal(tcx.def_span(def_id), "invalid linkage specified"),
-    }
-}
-
-fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: DefId) -> CodegenFnAttrs {
-    if cfg!(debug_assertions) {
-        let def_kind = tcx.def_kind(did);
-        assert!(
-            def_kind.has_codegen_attrs(),
-            "unexpected `def_kind` in `codegen_fn_attrs`: {def_kind:?}",
-        );
-    }
-
-    let did = did.expect_local();
-    let attrs = tcx.hir().attrs(tcx.hir().local_def_id_to_hir_id(did));
-    let mut codegen_fn_attrs = CodegenFnAttrs::new();
-    if tcx.should_inherit_track_caller(did) {
-        codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
-    }
-
-    let supported_target_features = tcx.supported_target_features(LOCAL_CRATE);
-
-    let mut inline_span = None;
-    let mut link_ordinal_span = None;
-    let mut no_sanitize_span = None;
-    for attr in attrs.iter() {
-        if attr.has_name(sym::cold) {
-            codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD;
-        } else if attr.has_name(sym::rustc_allocator) {
-            codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR;
-        } else if attr.has_name(sym::ffi_returns_twice) {
-            if tcx.is_foreign_item(did) {
-                codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_RETURNS_TWICE;
-            } else {
-                // `#[ffi_returns_twice]` is only allowed `extern fn`s.
-                struct_span_err!(
-                    tcx.sess,
-                    attr.span,
-                    E0724,
-                    "`#[ffi_returns_twice]` may only be used on foreign functions"
-                )
-                .emit();
-            }
-        } else if attr.has_name(sym::ffi_pure) {
-            if tcx.is_foreign_item(did) {
-                if attrs.iter().any(|a| a.has_name(sym::ffi_const)) {
-                    // `#[ffi_const]` functions cannot be `#[ffi_pure]`
-                    struct_span_err!(
-                        tcx.sess,
-                        attr.span,
-                        E0757,
-                        "`#[ffi_const]` function cannot be `#[ffi_pure]`"
-                    )
-                    .emit();
-                } else {
-                    codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_PURE;
-                }
-            } else {
-                // `#[ffi_pure]` is only allowed on foreign functions
-                struct_span_err!(
-                    tcx.sess,
-                    attr.span,
-                    E0755,
-                    "`#[ffi_pure]` may only be used on foreign functions"
-                )
-                .emit();
-            }
-        } else if attr.has_name(sym::ffi_const) {
-            if tcx.is_foreign_item(did) {
-                codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_CONST;
-            } else {
-                // `#[ffi_const]` is only allowed on foreign functions
-                struct_span_err!(
-                    tcx.sess,
-                    attr.span,
-                    E0756,
-                    "`#[ffi_const]` may only be used on foreign functions"
-                )
-                .emit();
-            }
-        } else if attr.has_name(sym::rustc_nounwind) {
-            codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
-        } else if attr.has_name(sym::rustc_reallocator) {
-            codegen_fn_attrs.flags |= CodegenFnAttrFlags::REALLOCATOR;
-        } else if attr.has_name(sym::rustc_deallocator) {
-            codegen_fn_attrs.flags |= CodegenFnAttrFlags::DEALLOCATOR;
-        } else if attr.has_name(sym::rustc_allocator_zeroed) {
-            codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR_ZEROED;
-        } else if attr.has_name(sym::naked) {
-            codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED;
-        } else if attr.has_name(sym::no_mangle) {
-            codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
-        } else if attr.has_name(sym::no_coverage) {
-            codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_COVERAGE;
-        } else if attr.has_name(sym::rustc_std_internal_symbol) {
-            codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
-        } else if attr.has_name(sym::used) {
-            let inner = attr.meta_item_list();
-            match inner.as_deref() {
-                Some([item]) if item.has_name(sym::linker) => {
-                    if !tcx.features().used_with_arg {
-                        feature_err(
-                            &tcx.sess.parse_sess,
-                            sym::used_with_arg,
-                            attr.span,
-                            "`#[used(linker)]` is currently unstable",
-                        )
-                        .emit();
-                    }
-                    codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED_LINKER;
-                }
-                Some([item]) if item.has_name(sym::compiler) => {
-                    if !tcx.features().used_with_arg {
-                        feature_err(
-                            &tcx.sess.parse_sess,
-                            sym::used_with_arg,
-                            attr.span,
-                            "`#[used(compiler)]` is currently unstable",
-                        )
-                        .emit();
-                    }
-                    codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED;
-                }
-                Some(_) => {
-                    tcx.sess.emit_err(errors::ExpectedUsedSymbol { span: attr.span });
-                }
-                None => {
-                    // Unfortunately, unconditionally using `llvm.used` causes
-                    // issues in handling `.init_array` with the gold linker,
-                    // but using `llvm.compiler.used` caused a nontrival amount
-                    // of unintentional ecosystem breakage -- particularly on
-                    // Mach-O targets.
-                    //
-                    // As a result, we emit `llvm.compiler.used` only on ELF
-                    // targets. This is somewhat ad-hoc, but actually follows
-                    // our pre-LLVM 13 behavior (prior to the ecosystem
-                    // breakage), and seems to match `clang`'s behavior as well
-                    // (both before and after LLVM 13), possibly because they
-                    // have similar compatibility concerns to us. See
-                    // https://github.com/rust-lang/rust/issues/47384#issuecomment-1019080146
-                    // and following comments for some discussion of this, as
-                    // well as the comments in `rustc_codegen_llvm` where these
-                    // flags are handled.
-                    //
-                    // Anyway, to be clear: this is still up in the air
-                    // somewhat, and is subject to change in the future (which
-                    // is a good thing, because this would ideally be a bit
-                    // more firmed up).
-                    let is_like_elf = !(tcx.sess.target.is_like_osx
-                        || tcx.sess.target.is_like_windows
-                        || tcx.sess.target.is_like_wasm);
-                    codegen_fn_attrs.flags |= if is_like_elf {
-                        CodegenFnAttrFlags::USED
-                    } else {
-                        CodegenFnAttrFlags::USED_LINKER
-                    };
-                }
-            }
-        } else if attr.has_name(sym::cmse_nonsecure_entry) {
-            if !matches!(tcx.fn_sig(did).abi(), abi::Abi::C { .. }) {
-                struct_span_err!(
-                    tcx.sess,
-                    attr.span,
-                    E0776,
-                    "`#[cmse_nonsecure_entry]` requires C ABI"
-                )
-                .emit();
-            }
-            if !tcx.sess.target.llvm_target.contains("thumbv8m") {
-                struct_span_err!(tcx.sess, attr.span, E0775, "`#[cmse_nonsecure_entry]` is only valid for targets with the TrustZone-M extension")
-                    .emit();
-            }
-            codegen_fn_attrs.flags |= CodegenFnAttrFlags::CMSE_NONSECURE_ENTRY;
-        } else if attr.has_name(sym::thread_local) {
-            codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL;
-        } else if attr.has_name(sym::track_caller) {
-            if !tcx.is_closure(did.to_def_id()) && tcx.fn_sig(did).abi() != abi::Abi::Rust {
-                struct_span_err!(tcx.sess, attr.span, E0737, "`#[track_caller]` requires Rust ABI")
-                    .emit();
-            }
-            if tcx.is_closure(did.to_def_id()) && !tcx.features().closure_track_caller {
-                feature_err(
-                    &tcx.sess.parse_sess,
-                    sym::closure_track_caller,
-                    attr.span,
-                    "`#[track_caller]` on closures is currently unstable",
-                )
-                .emit();
-            }
-            codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
-        } else if attr.has_name(sym::export_name) {
-            if let Some(s) = attr.value_str() {
-                if s.as_str().contains('\0') {
-                    // `#[export_name = ...]` will be converted to a null-terminated string,
-                    // so it may not contain any null characters.
-                    struct_span_err!(
-                        tcx.sess,
-                        attr.span,
-                        E0648,
-                        "`export_name` may not contain null characters"
-                    )
-                    .emit();
-                }
-                codegen_fn_attrs.export_name = Some(s);
-            }
-        } else if attr.has_name(sym::target_feature) {
-            if !tcx.is_closure(did.to_def_id())
-                && tcx.fn_sig(did).unsafety() == hir::Unsafety::Normal
-            {
-                if tcx.sess.target.is_like_wasm || tcx.sess.opts.actually_rustdoc {
-                    // The `#[target_feature]` attribute is allowed on
-                    // WebAssembly targets on all functions, including safe
-                    // ones. Other targets require that `#[target_feature]` is
-                    // only applied to unsafe functions (pending the
-                    // `target_feature_11` feature) because on most targets
-                    // execution of instructions that are not supported is
-                    // considered undefined behavior. For WebAssembly which is a
-                    // 100% safe target at execution time it's not possible to
-                    // execute undefined instructions, and even if a future
-                    // feature was added in some form for this it would be a
-                    // deterministic trap. There is no undefined behavior when
-                    // executing WebAssembly so `#[target_feature]` is allowed
-                    // on safe functions (but again, only for WebAssembly)
-                    //
-                    // Note that this is also allowed if `actually_rustdoc` so
-                    // if a target is documenting some wasm-specific code then
-                    // it's not spuriously denied.
-                } else if !tcx.features().target_feature_11 {
-                    let mut err = feature_err(
-                        &tcx.sess.parse_sess,
-                        sym::target_feature_11,
-                        attr.span,
-                        "`#[target_feature(..)]` can only be applied to `unsafe` functions",
-                    );
-                    err.span_label(tcx.def_span(did), "not an `unsafe` function");
-                    err.emit();
-                } else {
-                    check_target_feature_trait_unsafe(tcx, did, attr.span);
-                }
-            }
-            from_target_feature(
-                tcx,
-                attr,
-                supported_target_features,
-                &mut codegen_fn_attrs.target_features,
-            );
-        } else if attr.has_name(sym::linkage) {
-            if let Some(val) = attr.value_str() {
-                let linkage = Some(linkage_by_name(tcx, did, val.as_str()));
-                if tcx.is_foreign_item(did) {
-                    codegen_fn_attrs.import_linkage = linkage;
-                } else {
-                    codegen_fn_attrs.linkage = linkage;
-                }
-            }
-        } else if attr.has_name(sym::link_section) {
-            if let Some(val) = attr.value_str() {
-                if val.as_str().bytes().any(|b| b == 0) {
-                    let msg = format!(
-                        "illegal null byte in link_section \
-                         value: `{}`",
-                        &val
-                    );
-                    tcx.sess.span_err(attr.span, &msg);
-                } else {
-                    codegen_fn_attrs.link_section = Some(val);
-                }
-            }
-        } else if attr.has_name(sym::link_name) {
-            codegen_fn_attrs.link_name = attr.value_str();
-        } else if attr.has_name(sym::link_ordinal) {
-            link_ordinal_span = Some(attr.span);
-            if let ordinal @ Some(_) = check_link_ordinal(tcx, attr) {
-                codegen_fn_attrs.link_ordinal = ordinal;
-            }
-        } else if attr.has_name(sym::no_sanitize) {
-            no_sanitize_span = Some(attr.span);
-            if let Some(list) = attr.meta_item_list() {
-                for item in list.iter() {
-                    if item.has_name(sym::address) {
-                        codegen_fn_attrs.no_sanitize |= SanitizerSet::ADDRESS;
-                    } else if item.has_name(sym::cfi) {
-                        codegen_fn_attrs.no_sanitize |= SanitizerSet::CFI;
-                    } else if item.has_name(sym::kcfi) {
-                        codegen_fn_attrs.no_sanitize |= SanitizerSet::KCFI;
-                    } else if item.has_name(sym::memory) {
-                        codegen_fn_attrs.no_sanitize |= SanitizerSet::MEMORY;
-                    } else if item.has_name(sym::memtag) {
-                        codegen_fn_attrs.no_sanitize |= SanitizerSet::MEMTAG;
-                    } else if item.has_name(sym::shadow_call_stack) {
-                        codegen_fn_attrs.no_sanitize |= SanitizerSet::SHADOWCALLSTACK;
-                    } else if item.has_name(sym::thread) {
-                        codegen_fn_attrs.no_sanitize |= SanitizerSet::THREAD;
-                    } else if item.has_name(sym::hwaddress) {
-                        codegen_fn_attrs.no_sanitize |= SanitizerSet::HWADDRESS;
-                    } else {
-                        tcx.sess
-                            .struct_span_err(item.span(), "invalid argument for `no_sanitize`")
-                            .note("expected one of: `address`, `cfi`, `hwaddress`, `kcfi`, `memory`, `memtag`, `shadow-call-stack`, or `thread`")
-                            .emit();
-                    }
-                }
-            }
-        } else if attr.has_name(sym::instruction_set) {
-            codegen_fn_attrs.instruction_set = match attr.meta_kind() {
-                Some(MetaItemKind::List(ref items)) => match items.as_slice() {
-                    [NestedMetaItem::MetaItem(set)] => {
-                        let segments =
-                            set.path.segments.iter().map(|x| x.ident.name).collect::<Vec<_>>();
-                        match segments.as_slice() {
-                            [sym::arm, sym::a32] | [sym::arm, sym::t32] => {
-                                if !tcx.sess.target.has_thumb_interworking {
-                                    struct_span_err!(
-                                        tcx.sess.diagnostic(),
-                                        attr.span,
-                                        E0779,
-                                        "target does not support `#[instruction_set]`"
-                                    )
-                                    .emit();
-                                    None
-                                } else if segments[1] == sym::a32 {
-                                    Some(InstructionSetAttr::ArmA32)
-                                } else if segments[1] == sym::t32 {
-                                    Some(InstructionSetAttr::ArmT32)
-                                } else {
-                                    unreachable!()
-                                }
-                            }
-                            _ => {
-                                struct_span_err!(
-                                    tcx.sess.diagnostic(),
-                                    attr.span,
-                                    E0779,
-                                    "invalid instruction set specified",
-                                )
-                                .emit();
-                                None
-                            }
-                        }
-                    }
-                    [] => {
-                        struct_span_err!(
-                            tcx.sess.diagnostic(),
-                            attr.span,
-                            E0778,
-                            "`#[instruction_set]` requires an argument"
-                        )
-                        .emit();
-                        None
-                    }
-                    _ => {
-                        struct_span_err!(
-                            tcx.sess.diagnostic(),
-                            attr.span,
-                            E0779,
-                            "cannot specify more than one instruction set"
-                        )
-                        .emit();
-                        None
-                    }
-                },
-                _ => {
-                    struct_span_err!(
-                        tcx.sess.diagnostic(),
-                        attr.span,
-                        E0778,
-                        "must specify an instruction set"
-                    )
-                    .emit();
-                    None
-                }
-            };
-        } else if attr.has_name(sym::repr) {
-            codegen_fn_attrs.alignment = match attr.meta_item_list() {
-                Some(items) => match items.as_slice() {
-                    [item] => match item.name_value_literal() {
-                        Some((sym::align, literal)) => {
-                            let alignment = rustc_attr::parse_alignment(&literal.kind);
-
-                            match alignment {
-                                Ok(align) => Some(align),
-                                Err(msg) => {
-                                    struct_span_err!(
-                                        tcx.sess.diagnostic(),
-                                        attr.span,
-                                        E0589,
-                                        "invalid `repr(align)` attribute: {}",
-                                        msg
-                                    )
-                                    .emit();
-
-                                    None
-                                }
-                            }
-                        }
-                        _ => None,
-                    },
-                    [] => None,
-                    _ => None,
-                },
-                None => None,
-            };
-        }
-    }
-
-    codegen_fn_attrs.inline = attrs.iter().fold(InlineAttr::None, |ia, attr| {
-        if !attr.has_name(sym::inline) {
-            return ia;
-        }
-        match attr.meta_kind() {
-            Some(MetaItemKind::Word) => InlineAttr::Hint,
-            Some(MetaItemKind::List(ref items)) => {
-                inline_span = Some(attr.span);
-                if items.len() != 1 {
-                    struct_span_err!(
-                        tcx.sess.diagnostic(),
-                        attr.span,
-                        E0534,
-                        "expected one argument"
-                    )
-                    .emit();
-                    InlineAttr::None
-                } else if list_contains_name(&items, sym::always) {
-                    InlineAttr::Always
-                } else if list_contains_name(&items, sym::never) {
-                    InlineAttr::Never
-                } else {
-                    struct_span_err!(
-                        tcx.sess.diagnostic(),
-                        items[0].span(),
-                        E0535,
-                        "invalid argument"
-                    )
-                    .help("valid inline arguments are `always` and `never`")
-                    .emit();
-
-                    InlineAttr::None
-                }
-            }
-            Some(MetaItemKind::NameValue(_)) => ia,
-            None => ia,
-        }
-    });
-
-    codegen_fn_attrs.optimize = attrs.iter().fold(OptimizeAttr::None, |ia, attr| {
-        if !attr.has_name(sym::optimize) {
-            return ia;
-        }
-        let err = |sp, s| struct_span_err!(tcx.sess.diagnostic(), sp, E0722, "{}", s).emit();
-        match attr.meta_kind() {
-            Some(MetaItemKind::Word) => {
-                err(attr.span, "expected one argument");
-                ia
-            }
-            Some(MetaItemKind::List(ref items)) => {
-                inline_span = Some(attr.span);
-                if items.len() != 1 {
-                    err(attr.span, "expected one argument");
-                    OptimizeAttr::None
-                } else if list_contains_name(&items, sym::size) {
-                    OptimizeAttr::Size
-                } else if list_contains_name(&items, sym::speed) {
-                    OptimizeAttr::Speed
-                } else {
-                    err(items[0].span(), "invalid argument");
-                    OptimizeAttr::None
-                }
-            }
-            Some(MetaItemKind::NameValue(_)) => ia,
-            None => ia,
-        }
-    });
-
-    // #73631: closures inherit `#[target_feature]` annotations
-    if tcx.features().target_feature_11 && tcx.is_closure(did.to_def_id()) {
-        let owner_id = tcx.parent(did.to_def_id());
-        if tcx.def_kind(owner_id).has_codegen_attrs() {
-            codegen_fn_attrs
-                .target_features
-                .extend(tcx.codegen_fn_attrs(owner_id).target_features.iter().copied());
-        }
-    }
-
-    // If a function uses #[target_feature] it can't be inlined into general
-    // purpose functions as they wouldn't have the right target features
-    // enabled. For that reason we also forbid #[inline(always)] as it can't be
-    // respected.
-    if !codegen_fn_attrs.target_features.is_empty() {
-        if codegen_fn_attrs.inline == InlineAttr::Always {
-            if let Some(span) = inline_span {
-                tcx.sess.span_err(
-                    span,
-                    "cannot use `#[inline(always)]` with \
-                     `#[target_feature]`",
-                );
-            }
-        }
-    }
-
-    if !codegen_fn_attrs.no_sanitize.is_empty() {
-        if codegen_fn_attrs.inline == InlineAttr::Always {
-            if let (Some(no_sanitize_span), Some(inline_span)) = (no_sanitize_span, inline_span) {
-                let hir_id = tcx.hir().local_def_id_to_hir_id(did);
-                tcx.struct_span_lint_hir(
-                    lint::builtin::INLINE_NO_SANITIZE,
-                    hir_id,
-                    no_sanitize_span,
-                    "`no_sanitize` will have no effect after inlining",
-                    |lint| lint.span_note(inline_span, "inlining requested here"),
-                )
-            }
-        }
-    }
-
-    if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::NAKED) {
-        codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_COVERAGE;
-        codegen_fn_attrs.inline = InlineAttr::Never;
-    }
-
-    // Weak lang items have the same semantics as "std internal" symbols in the
-    // sense that they're preserved through all our LTO passes and only
-    // strippable by the linker.
-    //
-    // Additionally weak lang items have predetermined symbol names.
-    if WEAK_LANG_ITEMS.iter().any(|&l| tcx.lang_items().get(l) == Some(did.to_def_id())) {
-        codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
-    }
-    if let Some((name, _)) = lang_items::extract(attrs)
-        && let Some(lang_item) = LangItem::from_name(name)
-        && let Some(link_name) = lang_item.link_name()
-    {
-        codegen_fn_attrs.export_name = Some(link_name);
-        codegen_fn_attrs.link_name = Some(link_name);
-    }
-    check_link_name_xor_ordinal(tcx, &codegen_fn_attrs, link_ordinal_span);
-
-    // Internal symbols to the standard library all have no_mangle semantics in
-    // that they have defined symbol names present in the function name. This
-    // also applies to weak symbols where they all have known symbol names.
-    if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) {
-        codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
-    }
-
-    // Any linkage to LLVM intrinsics for now forcibly marks them all as never
-    // unwinds since LLVM sometimes can't handle codegen which `invoke`s
-    // intrinsic functions.
-    if let Some(name) = &codegen_fn_attrs.link_name {
-        if name.as_str().starts_with("llvm.") {
-            codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
-        }
-    }
-
-    codegen_fn_attrs
-}
-
-/// Computes the set of target features used in a function for the purposes of
-/// inline assembly.
-fn asm_target_features<'tcx>(tcx: TyCtxt<'tcx>, did: DefId) -> &'tcx FxHashSet<Symbol> {
-    let mut target_features = tcx.sess.unstable_target_features.clone();
-    if tcx.def_kind(did).has_codegen_attrs() {
-        let attrs = tcx.codegen_fn_attrs(did);
-        target_features.extend(&attrs.target_features);
-        match attrs.instruction_set {
-            None => {}
-            Some(InstructionSetAttr::ArmA32) => {
-                target_features.remove(&sym::thumb_mode);
-            }
-            Some(InstructionSetAttr::ArmT32) => {
-                target_features.insert(sym::thumb_mode);
-            }
-        }
-    }
-
-    tcx.arena.alloc(target_features)
-}
-
-/// Checks if the provided DefId is a method in a trait impl for a trait which has track_caller
-/// applied to the method prototype.
-fn should_inherit_track_caller(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
-    if let Some(impl_item) = tcx.opt_associated_item(def_id)
-        && let ty::AssocItemContainer::ImplContainer = impl_item.container
-        && let Some(trait_item) = impl_item.trait_item_def_id
-    {
-        return tcx
-            .codegen_fn_attrs(trait_item)
-            .flags
-            .intersects(CodegenFnAttrFlags::TRACK_CALLER);
-    }
-
-    false
-}
-
-fn check_link_ordinal(tcx: TyCtxt<'_>, attr: &ast::Attribute) -> Option<u16> {
-    use rustc_ast::{LitIntType, LitKind, MetaItemLit};
-    if !tcx.features().raw_dylib && tcx.sess.target.arch == "x86" {
-        feature_err(
-            &tcx.sess.parse_sess,
-            sym::raw_dylib,
-            attr.span,
-            "`#[link_ordinal]` is unstable on x86",
-        )
-        .emit();
-    }
-    let meta_item_list = attr.meta_item_list();
-    let meta_item_list = meta_item_list.as_deref();
-    let sole_meta_list = match meta_item_list {
-        Some([item]) => item.lit(),
-        Some(_) => {
-            tcx.sess
-                .struct_span_err(attr.span, "incorrect number of arguments to `#[link_ordinal]`")
-                .note("the attribute requires exactly one argument")
-                .emit();
-            return None;
-        }
-        _ => None,
-    };
-    if let Some(MetaItemLit { kind: LitKind::Int(ordinal, LitIntType::Unsuffixed), .. }) =
-        sole_meta_list
-    {
-        // According to the table at https://docs.microsoft.com/en-us/windows/win32/debug/pe-format#import-header,
-        // the ordinal must fit into 16 bits.  Similarly, the Ordinal field in COFFShortExport (defined
-        // in llvm/include/llvm/Object/COFFImportFile.h), which we use to communicate import information
-        // to LLVM for `#[link(kind = "raw-dylib"_])`, is also defined to be uint16_t.
-        //
-        // FIXME: should we allow an ordinal of 0?  The MSVC toolchain has inconsistent support for this:
-        // both LINK.EXE and LIB.EXE signal errors and abort when given a .DEF file that specifies
-        // a zero ordinal.  However, llvm-dlltool is perfectly happy to generate an import library
-        // for such a .DEF file, and MSVC's LINK.EXE is also perfectly happy to consume an import
-        // library produced by LLVM with an ordinal of 0, and it generates an .EXE.  (I don't know yet
-        // if the resulting EXE runs, as I haven't yet built the necessary DLL -- see earlier comment
-        // about LINK.EXE failing.)
-        if *ordinal <= u16::MAX as u128 {
-            Some(*ordinal as u16)
-        } else {
-            let msg = format!("ordinal value in `link_ordinal` is too large: `{}`", &ordinal);
-            tcx.sess
-                .struct_span_err(attr.span, &msg)
-                .note("the value may not exceed `u16::MAX`")
-                .emit();
-            None
-        }
-    } else {
-        tcx.sess
-            .struct_span_err(attr.span, "illegal ordinal format in `link_ordinal`")
-            .note("an unsuffixed integer value, e.g., `1`, is expected")
-            .emit();
-        None
-    }
-}
-
-fn check_link_name_xor_ordinal(
-    tcx: TyCtxt<'_>,
-    codegen_fn_attrs: &CodegenFnAttrs,
-    inline_span: Option<Span>,
-) {
-    if codegen_fn_attrs.link_name.is_none() || codegen_fn_attrs.link_ordinal.is_none() {
-        return;
-    }
-    let msg = "cannot use `#[link_name]` with `#[link_ordinal]`";
-    if let Some(span) = inline_span {
-        tcx.sess.span_err(span, msg);
-    } else {
-        tcx.sess.err(msg);
-    }
-}
-
-/// Checks the function annotated with `#[target_feature]` is not a safe
-/// trait method implementation, reporting an error if it is.
-fn check_target_feature_trait_unsafe(tcx: TyCtxt<'_>, id: LocalDefId, attr_span: Span) {
-    let hir_id = tcx.hir().local_def_id_to_hir_id(id);
-    let node = tcx.hir().get(hir_id);
-    if let Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Fn(..), .. }) = node {
-        let parent_id = tcx.hir().get_parent_item(hir_id);
-        let parent_item = tcx.hir().expect_item(parent_id.def_id);
-        if let hir::ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }) = parent_item.kind {
-            tcx.sess
-                .struct_span_err(
-                    attr_span,
-                    "`#[target_feature(..)]` cannot be applied to safe trait method",
-                )
-                .span_label(attr_span, "cannot be applied to safe trait method")
-                .span_label(tcx.def_span(id), "not an `unsafe` function")
-                .emit();
-        }
-    }
-}
diff --git a/compiler/rustc_hir_analysis/src/collect/lifetimes.rs b/compiler/rustc_hir_analysis/src/collect/lifetimes.rs
index 9a7b261fffd..b4ad3467e7d 100644
--- a/compiler/rustc_hir_analysis/src/collect/lifetimes.rs
+++ b/compiler/rustc_hir_analysis/src/collect/lifetimes.rs
@@ -1749,7 +1749,7 @@ fn is_late_bound_map(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Option<&FxIndexSet<
                 ty::Param(param_ty) => {
                     self.arg_is_constrained[param_ty.index as usize] = true;
                 }
-                ty::Projection(_) => return ControlFlow::Continue(()),
+                ty::Alias(ty::Projection, _) => return ControlFlow::Continue(()),
                 _ => (),
             }
             t.super_visit_with(self)
diff --git a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
index 45e241f4e09..79d75231e5d 100644
--- a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
+++ b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
@@ -75,7 +75,7 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericP
 
     const NO_GENERICS: &hir::Generics<'_> = hir::Generics::empty();
 
-    // We use an `IndexSet` to preserves order of insertion.
+    // 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::Predicate<'_>, Span)> = FxIndexSet::default();
 
@@ -97,11 +97,7 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericP
             | ItemKind::Struct(_, ref generics)
             | ItemKind::Union(_, ref generics) => *generics,
 
-            ItemKind::Trait(_, _, ref generics, ..) => {
-                is_trait = Some(ty::TraitRef::identity(tcx, def_id));
-                *generics
-            }
-            ItemKind::TraitAlias(ref generics, _) => {
+            ItemKind::Trait(_, _, ref generics, ..) | ItemKind::TraitAlias(ref generics, _) => {
                 is_trait = Some(ty::TraitRef::identity(tcx, def_id));
                 *generics
             }
@@ -406,14 +402,15 @@ pub(super) fn explicit_predicates_of<'tcx>(
             // For a predicate from a where clause to become a bound on an
             // associated type:
             // * It must use the identity substs of the item.
-            //     * Since any generic parameters on the item are not in scope,
-            //       this means that the item is not a GAT, and its identity
-            //       substs are the same as the trait's.
+            //   * We're in the scope of the trait, so we can't name any
+            //     parameters of the GAT. That means that all we need to
+            //     check are that the substs of the projection are the
+            //     identity substs of the trait.
             // * It must be an associated type for this trait (*not* a
             //   supertrait).
-            if let ty::Projection(projection) = ty.kind() {
+            if let ty::Alias(ty::Projection, projection) = ty.kind() {
                 projection.substs == trait_identity_substs
-                    && tcx.associated_item(projection.item_def_id).container_id(tcx) == def_id
+                    && tcx.associated_item(projection.def_id).container_id(tcx) == def_id
             } else {
                 false
             }
diff --git a/compiler/rustc_hir_analysis/src/collect/type_of.rs b/compiler/rustc_hir_analysis/src/collect/type_of.rs
index 9bd1715ce39..b678990f94e 100644
--- a/compiler/rustc_hir_analysis/src/collect/type_of.rs
+++ b/compiler/rustc_hir_analysis/src/collect/type_of.rs
@@ -52,7 +52,7 @@ pub(super) fn opt_const_param_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Option<
             // Using the ItemCtxt convert the HIR for the unresolved assoc type into a
             // ty which is a fully resolved projection.
             // For the code example above, this would mean converting Self::Assoc<3>
-            // into a ty::Projection(<Self as Foo>::Assoc<3>)
+            // into a ty::Alias(ty::Projection, <Self as Foo>::Assoc<3>)
             let item_hir_id = tcx
                 .hir()
                 .parent_iter(hir_id)
@@ -68,8 +68,8 @@ pub(super) fn opt_const_param_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Option<
             // the def_id that this query was called with. We filter to only type and const args here
             // as a precaution for if it's ever allowed to elide lifetimes in GAT's. It currently isn't
             // but it can't hurt to be safe ^^
-            if let ty::Projection(projection) = ty.kind() {
-                let generics = tcx.generics_of(projection.item_def_id);
+            if let ty::Alias(ty::Projection, projection) = ty.kind() {
+                let generics = tcx.generics_of(projection.def_id);
 
                 let arg_index = segment
                     .args
@@ -666,7 +666,7 @@ fn find_opaque_ty_constraints_for_tait(tcx: TyCtxt<'_>, def_id: LocalDefId) -> T
 
     let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
     let scope = tcx.hir().get_defining_scope(hir_id);
-    let mut locator = ConstraintLocator { def_id: def_id, tcx, found: None, typeck_types: vec![] };
+    let mut locator = ConstraintLocator { def_id, tcx, found: None, typeck_types: vec![] };
 
     debug!(?scope);
 
@@ -803,7 +803,7 @@ fn find_opaque_ty_constraints_for_rpit(
     if let Some(concrete) = concrete {
         let scope = tcx.hir().local_def_id_to_hir_id(owner_def_id);
         debug!(?scope);
-        let mut locator = ConstraintChecker { def_id: def_id, tcx, found: concrete };
+        let mut locator = ConstraintChecker { def_id, tcx, found: concrete };
 
         match tcx.hir().get(scope) {
             Node::Item(it) => intravisit::walk_item(&mut locator, it),
diff --git a/compiler/rustc_hir_analysis/src/constrained_generic_params.rs b/compiler/rustc_hir_analysis/src/constrained_generic_params.rs
index b4057df7896..95c971c0d78 100644
--- a/compiler/rustc_hir_analysis/src/constrained_generic_params.rs
+++ b/compiler/rustc_hir_analysis/src/constrained_generic_params.rs
@@ -59,7 +59,7 @@ struct ParameterCollector {
 impl<'tcx> TypeVisitor<'tcx> for ParameterCollector {
     fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
         match *t.kind() {
-            ty::Projection(..) if !self.include_nonconstraining => {
+            ty::Alias(ty::Projection, ..) if !self.include_nonconstraining => {
                 // projections are not injective
                 return ControlFlow::CONTINUE;
             }
diff --git a/compiler/rustc_hir_analysis/src/errors.rs b/compiler/rustc_hir_analysis/src/errors.rs
index c92ab749bc1..d383fcacb3a 100644
--- a/compiler/rustc_hir_analysis/src/errors.rs
+++ b/compiler/rustc_hir_analysis/src/errors.rs
@@ -52,6 +52,17 @@ pub struct LifetimesOrBoundsMismatchOnTrait {
 }
 
 #[derive(Diagnostic)]
+#[diag(hir_analysis_async_trait_impl_should_be_async)]
+pub struct AsyncTraitImplShouldBeAsync {
+    #[primary_span]
+    // #[label]
+    pub span: Span,
+    #[label(trait_item_label)]
+    pub trait_item_span: Option<Span>,
+    pub method_name: Symbol,
+}
+
+#[derive(Diagnostic)]
 #[diag(hir_analysis_drop_impl_on_wrong_item, code = "E0120")]
 pub struct DropImplOnWrongItem {
     #[primary_span]
@@ -254,13 +265,6 @@ pub struct ExternCrateNotIdiomatic {
 }
 
 #[derive(Diagnostic)]
-#[diag(hir_analysis_expected_used_symbol)]
-pub struct ExpectedUsedSymbol {
-    #[primary_span]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
 #[diag(hir_analysis_const_impl_for_non_const_trait)]
 pub struct ConstImplForNonConstTrait {
     #[primary_span]
diff --git a/compiler/rustc_hir_analysis/src/outlives/implicit_infer.rs b/compiler/rustc_hir_analysis/src/outlives/implicit_infer.rs
index 90c6edb65e4..af8d7e85158 100644
--- a/compiler/rustc_hir_analysis/src/outlives/implicit_infer.rs
+++ b/compiler/rustc_hir_analysis/src/outlives/implicit_infer.rs
@@ -196,13 +196,13 @@ fn insert_required_predicates_to_be_wf<'tcx>(
                 }
             }
 
-            ty::Projection(obj) => {
+            ty::Alias(ty::Projection, obj) => {
                 // This corresponds to `<T as Foo<'a>>::Bar`. In this case, we should use the
                 // explicit predicates as well.
                 debug!("Projection");
                 check_explicit_predicates(
                     tcx,
-                    tcx.parent(obj.item_def_id),
+                    tcx.parent(obj.def_id),
                     obj.substs,
                     required_predicates,
                     explicit_map,
diff --git a/compiler/rustc_hir_analysis/src/outlives/utils.rs b/compiler/rustc_hir_analysis/src/outlives/utils.rs
index 0409c7081dc..b51b740d08e 100644
--- a/compiler/rustc_hir_analysis/src/outlives/utils.rs
+++ b/compiler/rustc_hir_analysis/src/outlives/utils.rs
@@ -90,7 +90,7 @@ pub(crate) fn insert_outlives_predicate<'tcx>(
                         // ```
                         //
                         // Here we want to add an explicit `where <T as Iterator>::Item: 'a`.
-                        let ty: Ty<'tcx> = tcx.mk_projection(proj_ty.item_def_id, proj_ty.substs);
+                        let ty: Ty<'tcx> = tcx.mk_projection(proj_ty.def_id, proj_ty.substs);
                         required_predicates
                             .entry(ty::OutlivesPredicate(ty.into(), outlived_region))
                             .or_insert(span);
diff --git a/compiler/rustc_hir_analysis/src/variance/constraints.rs b/compiler/rustc_hir_analysis/src/variance/constraints.rs
index 6ce0c18bf45..5e4d82b6fd5 100644
--- a/compiler/rustc_hir_analysis/src/variance/constraints.rs
+++ b/compiler/rustc_hir_analysis/src/variance/constraints.rs
@@ -249,14 +249,10 @@ impl<'a, 'tcx> ConstraintContext<'a, 'tcx> {
                 self.add_constraints_from_substs(current, def.did(), substs, variance);
             }
 
-            ty::Projection(ref data) => {
+            ty::Alias(_, ref data) => {
                 self.add_constraints_from_invariant_substs(current, data.substs, variance);
             }
 
-            ty::Opaque(_, substs) => {
-                self.add_constraints_from_invariant_substs(current, substs, variance);
-            }
-
             ty::Dynamic(data, r, _) => {
                 // The type `Foo<T+'a>` is contravariant w/r/t `'a`:
                 let contra = self.contravariant(variance);
diff --git a/compiler/rustc_hir_analysis/src/variance/mod.rs b/compiler/rustc_hir_analysis/src/variance/mod.rs
index 8b2719c2f8a..24008f88814 100644
--- a/compiler/rustc_hir_analysis/src/variance/mod.rs
+++ b/compiler/rustc_hir_analysis/src/variance/mod.rs
@@ -111,11 +111,13 @@ fn variance_of_opaque(tcx: TyCtxt<'_>, item_def_id: LocalDefId) -> &[ty::Varianc
         #[instrument(level = "trace", skip(self), ret)]
         fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
             match t.kind() {
-                ty::Opaque(def_id, substs) => self.visit_opaque(*def_id, substs),
-                ty::Projection(proj)
-                    if self.tcx.def_kind(proj.item_def_id) == DefKind::ImplTraitPlaceholder =>
+                ty::Alias(_, ty::AliasTy { def_id, substs, .. })
+                    if matches!(
+                        self.tcx.def_kind(*def_id),
+                        DefKind::OpaqueTy | DefKind::ImplTraitPlaceholder
+                    ) =>
                 {
-                    self.visit_opaque(proj.item_def_id, proj.substs)
+                    self.visit_opaque(*def_id, substs)
                 }
                 _ => t.super_visit_with(self),
             }
@@ -158,7 +160,7 @@ fn variance_of_opaque(tcx: TyCtxt<'_>, item_def_id: LocalDefId) -> &[ty::Varianc
         // instead of requiring an additional `+ 'a`.
         match pred.kind().skip_binder() {
             ty::PredicateKind::Clause(ty::Clause::Trait(ty::TraitPredicate {
-                trait_ref: ty::TraitRef { def_id: _, substs },
+                trait_ref: ty::TraitRef { def_id: _, substs, .. },
                 constness: _,
                 polarity: _,
             })) => {
@@ -167,7 +169,7 @@ fn variance_of_opaque(tcx: TyCtxt<'_>, item_def_id: LocalDefId) -> &[ty::Varianc
                 }
             }
             ty::PredicateKind::Clause(ty::Clause::Projection(ty::ProjectionPredicate {
-                projection_ty: ty::ProjectionTy { substs, item_def_id: _ },
+                projection_ty: ty::AliasTy { substs, .. },
                 term,
             })) => {
                 for subst in &substs[1..] {