Auto merge of #121252 - fmease:rollup-x7zogl8, r=fmease

Rollup of 7 pull requests

Successful merges:

 - #120526 (rustdoc: Correctly handle long crate names on mobile)
 - #121100 (Detect when method call on argument could be removed to fulfill failed trait bound)
 - #121160 (rustdoc: fix and refactor HTML rendering a bit)
 - #121198 (Add more checks for `unnamed_fields` during HIR analysis)
 - #121218 (Fix missing trait impls for type in rustc docs)
 - #121221 (AstConv: Refactor lowering of associated item bindings a bit)
 - #121237 (Use better heuristic for printing Cargo specific diagnostics)

r? `@ghost`
`@rustbot` modify labels: rollup

15 files changed, 210 insertions, 195 deletions

diff --git a/compiler/rustc_codegen_ssa/src/errors.rs b/compiler/rustc_codegen_ssa/src/errors.rs
index 3d7903b5efb..e42a8bd9ed9 100644
--- a/compiler/rustc_codegen_ssa/src/errors.rs
+++ b/compiler/rustc_codegen_ssa/src/errors.rs
@@ -362,8 +362,11 @@ impl<G: EmissionGuarantee> IntoDiagnostic<'_, G> for LinkingFailed<'_> {
         // which by now we have no way to translate.
         if contains_undefined_ref {
             diag.note(fluent::codegen_ssa_extern_funcs_not_found)
-                .note(fluent::codegen_ssa_specify_libraries_to_link)
-                .note(fluent::codegen_ssa_use_cargo_directive);
+                .note(fluent::codegen_ssa_specify_libraries_to_link);
+
+            if rustc_session::utils::was_invoked_from_cargo() {
+                diag.note(fluent::codegen_ssa_use_cargo_directive);
+            }
         }
         diag
     }
diff --git a/compiler/rustc_hir/src/hir.rs b/compiler/rustc_hir/src/hir.rs
index 77044df9a40..fcb15925f6a 100644
--- a/compiler/rustc_hir/src/hir.rs
+++ b/compiler/rustc_hir/src/hir.rs
@@ -2998,6 +2998,12 @@ impl<'hir> Item<'hir> {
         ItemId { owner_id: self.owner_id }
     }
 
+    /// Check if this is an [`ItemKind::Enum`], [`ItemKind::Struct`] or
+    /// [`ItemKind::Union`].
+    pub fn is_adt(&self) -> bool {
+        matches!(self.kind, ItemKind::Enum(..) | ItemKind::Struct(..) | ItemKind::Union(..))
+    }
+
     expect_methods_self_kind! {
         expect_extern_crate, Option<Symbol>, ItemKind::ExternCrate(s), *s;
 
diff --git a/compiler/rustc_hir_analysis/messages.ftl b/compiler/rustc_hir_analysis/messages.ftl
index a61cfd0e4ce..f32b14aca23 100644
--- a/compiler/rustc_hir_analysis/messages.ftl
+++ b/compiler/rustc_hir_analysis/messages.ftl
@@ -198,6 +198,8 @@ hir_analysis_invalid_union_field =
 hir_analysis_invalid_union_field_sugg =
     wrap the field type in `ManuallyDrop<...>`
 
+hir_analysis_invalid_unnamed_field_ty = unnamed fields can only have struct or union types
+
 hir_analysis_late_bound_const_in_apit = `impl Trait` can only mention const parameters from an fn or impl
     .label = const parameter declared here
 
diff --git a/compiler/rustc_hir_analysis/src/astconv/bounds.rs b/compiler/rustc_hir_analysis/src/astconv/bounds.rs
index dab1e2d5253..6940b4a5045 100644
--- a/compiler/rustc_hir_analysis/src/astconv/bounds.rs
+++ b/compiler/rustc_hir_analysis/src/astconv/bounds.rs
@@ -9,9 +9,7 @@ use rustc_span::{ErrorGuaranteed, Span};
 use rustc_trait_selection::traits;
 use smallvec::SmallVec;
 
-use crate::astconv::{
-    AstConv, ConvertedBinding, ConvertedBindingKind, OnlySelfBounds, PredicateFilter,
-};
+use crate::astconv::{AstConv, OnlySelfBounds, PredicateFilter};
 use crate::bounds::Bounds;
 use crate::errors;
 
@@ -238,7 +236,7 @@ impl<'tcx> dyn AstConv<'tcx> + '_ {
         &self,
         hir_ref_id: hir::HirId,
         trait_ref: ty::PolyTraitRef<'tcx>,
-        binding: &ConvertedBinding<'_, 'tcx>,
+        binding: &hir::TypeBinding<'tcx>,
         bounds: &mut Bounds<'tcx>,
         speculative: bool,
         dup_bindings: &mut FxIndexMap<DefId, Span>,
@@ -263,21 +261,20 @@ impl<'tcx> dyn AstConv<'tcx> + '_ {
 
         let tcx = self.tcx();
 
-        let assoc_kind =
-            if binding.gen_args.parenthesized == hir::GenericArgsParentheses::ReturnTypeNotation {
-                ty::AssocKind::Fn
-            } else if let ConvertedBindingKind::Equality(term) = binding.kind
-                && let ty::TermKind::Const(_) = term.node.unpack()
-            {
-                ty::AssocKind::Const
-            } else {
-                ty::AssocKind::Type
-            };
+        let assoc_kind = if binding.gen_args.parenthesized
+            == hir::GenericArgsParentheses::ReturnTypeNotation
+        {
+            ty::AssocKind::Fn
+        } else if let hir::TypeBindingKind::Equality { term: hir::Term::Const(_) } = binding.kind {
+            ty::AssocKind::Const
+        } else {
+            ty::AssocKind::Type
+        };
 
         let candidate = if self.trait_defines_associated_item_named(
             trait_ref.def_id(),
             assoc_kind,
-            binding.item_name,
+            binding.ident,
         ) {
             // Simple case: The assoc item is defined in the current trait.
             trait_ref
@@ -289,14 +286,14 @@ impl<'tcx> dyn AstConv<'tcx> + '_ {
                 trait_ref.skip_binder().print_only_trait_name(),
                 None,
                 assoc_kind,
-                binding.item_name,
+                binding.ident,
                 path_span,
-                Some(&binding),
+                Some(binding),
             )?
         };
 
         let (assoc_ident, def_scope) =
-            tcx.adjust_ident_and_get_scope(binding.item_name, candidate.def_id(), hir_ref_id);
+            tcx.adjust_ident_and_get_scope(binding.ident, candidate.def_id(), hir_ref_id);
 
         // We have already adjusted the item name above, so compare with `.normalize_to_macros_2_0()`
         // instead of calling `filter_by_name_and_kind` which would needlessly normalize the
@@ -312,7 +309,7 @@ impl<'tcx> dyn AstConv<'tcx> + '_ {
                 .dcx()
                 .struct_span_err(
                     binding.span,
-                    format!("{} `{}` is private", assoc_item.kind, binding.item_name),
+                    format!("{} `{}` is private", assoc_item.kind, binding.ident),
                 )
                 .with_span_label(binding.span, format!("private {}", assoc_item.kind))
                 .emit();
@@ -327,7 +324,7 @@ impl<'tcx> dyn AstConv<'tcx> + '_ {
                     tcx.dcx().emit_err(errors::ValueOfAssociatedStructAlreadySpecified {
                         span: binding.span,
                         prev_span: *prev_span,
-                        item_name: binding.item_name,
+                        item_name: binding.ident,
                         def_path: tcx.def_path_str(assoc_item.container_id(tcx)),
                     });
                 })
@@ -390,14 +387,12 @@ impl<'tcx> dyn AstConv<'tcx> + '_ {
             {
                 alias_ty
             } else {
-                return Err(self.tcx().dcx().emit_err(
-                    crate::errors::ReturnTypeNotationOnNonRpitit {
-                        span: binding.span,
-                        ty: tcx.liberate_late_bound_regions(assoc_item.def_id, output),
-                        fn_span: tcx.hir().span_if_local(assoc_item.def_id),
-                        note: (),
-                    },
-                ));
+                return Err(tcx.dcx().emit_err(crate::errors::ReturnTypeNotationOnNonRpitit {
+                    span: binding.span,
+                    ty: tcx.liberate_late_bound_regions(assoc_item.def_id, output),
+                    fn_span: tcx.hir().span_if_local(assoc_item.def_id),
+                    note: (),
+                }));
             };
 
             // Finally, move the fn return type's bound vars over to account for the early bound
@@ -410,9 +405,11 @@ impl<'tcx> dyn AstConv<'tcx> + '_ {
             let bound_vars = tcx.late_bound_vars(binding.hir_id);
             ty::Binder::bind_with_vars(instantiation_output, bound_vars)
         } else {
-            // Append the generic arguments of the associated type to the `trait_ref`.
+            // Create the generic arguments for the associated type or constant by joining the
+            // parent arguments (the arguments of the trait) and the own arguments (the ones of
+            // the associated item itself) and construct an alias type using them.
             candidate.map_bound(|trait_ref| {
-                let ident = Ident::new(assoc_item.name, binding.item_name.span);
+                let ident = Ident::new(assoc_item.name, binding.ident.span);
                 let item_segment = hir::PathSegment {
                     ident,
                     hir_id: binding.hir_id,
@@ -421,77 +418,82 @@ impl<'tcx> dyn AstConv<'tcx> + '_ {
                     infer_args: false,
                 };
 
-                let args_trait_ref_and_assoc_item = self.create_args_for_associated_item(
+                let alias_args = self.create_args_for_associated_item(
                     path_span,
                     assoc_item.def_id,
                     &item_segment,
                     trait_ref.args,
                 );
+                debug!(?alias_args);
 
-                debug!(?args_trait_ref_and_assoc_item);
-
-                ty::AliasTy::new(tcx, assoc_item.def_id, args_trait_ref_and_assoc_item)
+                // Note that we're indeed also using `AliasTy` (alias *type*) for associated
+                // *constants* to represent *const projections*. Alias *term* would be a more
+                // appropriate name but alas.
+                ty::AliasTy::new(tcx, assoc_item.def_id, alias_args)
             })
         };
 
-        if !speculative {
-            // Find any late-bound regions declared in `ty` that are not
-            // declared in the trait-ref or assoc_item. These are not well-formed.
-            //
-            // Example:
-            //
-            //     for<'a> <T as Iterator>::Item = &'a str // <-- 'a is bad
-            //     for<'a> <T as FnMut<(&'a u32,)>>::Output = &'a str // <-- 'a is ok
-            if let ConvertedBindingKind::Equality(ty) = binding.kind {
-                let late_bound_in_trait_ref =
-                    tcx.collect_constrained_late_bound_regions(&projection_ty);
-                let late_bound_in_ty =
-                    tcx.collect_referenced_late_bound_regions(&trait_ref.rebind(ty.node));
-                debug!(?late_bound_in_trait_ref);
-                debug!(?late_bound_in_ty);
-
-                // FIXME: point at the type params that don't have appropriate lifetimes:
-                // struct S1<F: for<'a> Fn(&i32, &i32) -> &'a i32>(F);
-                //                         ----  ----     ^^^^^^^
-                self.validate_late_bound_regions(
-                    late_bound_in_trait_ref,
-                    late_bound_in_ty,
-                    |br_name| {
-                        struct_span_code_err!(
-                            tcx.dcx(),
-                            binding.span,
-                            E0582,
-                            "binding for associated type `{}` references {}, \
-                             which does not appear in the trait input types",
-                            binding.item_name,
-                            br_name
-                        )
-                    },
-                );
-            }
-        }
-
         match binding.kind {
-            ConvertedBindingKind::Equality(..) if let ty::AssocKind::Fn = assoc_kind => {
-                return Err(self.tcx().dcx().emit_err(
-                    crate::errors::ReturnTypeNotationEqualityBound { span: binding.span },
-                ));
+            hir::TypeBindingKind::Equality { .. } if let ty::AssocKind::Fn = assoc_kind => {
+                return Err(tcx.dcx().emit_err(crate::errors::ReturnTypeNotationEqualityBound {
+                    span: binding.span,
+                }));
             }
-            ConvertedBindingKind::Equality(term) => {
+            hir::TypeBindingKind::Equality { term } => {
+                let term = match term {
+                    hir::Term::Ty(ty) => self.ast_ty_to_ty(ty).into(),
+                    hir::Term::Const(ct) => ty::Const::from_anon_const(tcx, ct.def_id).into(),
+                };
+
+                if !speculative {
+                    // Find any late-bound regions declared in `ty` that are not
+                    // declared in the trait-ref or assoc_item. These are not well-formed.
+                    //
+                    // Example:
+                    //
+                    //     for<'a> <T as Iterator>::Item = &'a str // <-- 'a is bad
+                    //     for<'a> <T as FnMut<(&'a u32,)>>::Output = &'a str // <-- 'a is ok
+                    let late_bound_in_projection_ty =
+                        tcx.collect_constrained_late_bound_regions(&projection_ty);
+                    let late_bound_in_term =
+                        tcx.collect_referenced_late_bound_regions(&trait_ref.rebind(term));
+                    debug!(?late_bound_in_projection_ty);
+                    debug!(?late_bound_in_term);
+
+                    // FIXME: point at the type params that don't have appropriate lifetimes:
+                    // struct S1<F: for<'a> Fn(&i32, &i32) -> &'a i32>(F);
+                    //                         ----  ----     ^^^^^^^
+                    // NOTE(associated_const_equality): This error should be impossible to trigger
+                    //                                  with associated const equality bounds.
+                    self.validate_late_bound_regions(
+                        late_bound_in_projection_ty,
+                        late_bound_in_term,
+                        |br_name| {
+                            struct_span_code_err!(
+                                tcx.dcx(),
+                                binding.span,
+                                E0582,
+                                "binding for associated type `{}` references {}, \
+                                 which does not appear in the trait input types",
+                                binding.ident,
+                                br_name
+                            )
+                        },
+                    );
+                }
+
                 // "Desugar" a constraint like `T: Iterator<Item = u32>` this to
                 // the "projection predicate" for:
                 //
                 // `<T as Iterator>::Item = u32`
                 bounds.push_projection_bound(
                     tcx,
-                    projection_ty.map_bound(|projection_ty| ty::ProjectionPredicate {
-                        projection_ty,
-                        term: term.node,
-                    }),
+                    projection_ty
+                        .map_bound(|projection_ty| ty::ProjectionPredicate { projection_ty, term }),
                     binding.span,
                 );
             }
-            ConvertedBindingKind::Constraint(ast_bounds) => {
+            hir::TypeBindingKind::Constraint { bounds: ast_bounds } => {
                 // "Desugar" a constraint like `T: Iterator<Item: Debug>` to
                 //
                 // `<T as Iterator>::Item: Debug`
diff --git a/compiler/rustc_hir_analysis/src/astconv/errors.rs b/compiler/rustc_hir_analysis/src/astconv/errors.rs
index ea8d364bba6..ad34c31ef8f 100644
--- a/compiler/rustc_hir_analysis/src/astconv/errors.rs
+++ b/compiler/rustc_hir_analysis/src/astconv/errors.rs
@@ -1,4 +1,4 @@
-use crate::astconv::{AstConv, ConvertedBindingKind};
+use crate::astconv::AstConv;
 use crate::errors::{
     self, AssocTypeBindingNotAllowed, ManualImplementation, MissingTypeParams,
     ParenthesizedFnTraitExpansion,
@@ -111,7 +111,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         assoc_kind: ty::AssocKind,
         assoc_name: Ident,
         span: Span,
-        binding: Option<&super::ConvertedBinding<'_, 'tcx>>,
+        binding: Option<&hir::TypeBinding<'tcx>>,
     ) -> ErrorGuaranteed
     where
         I: Iterator<Item = ty::PolyTraitRef<'tcx>>,
@@ -243,7 +243,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                         None,
                     ) && suggested_name != assoc_name.name
                     {
-                        // We suggested constraining a type parameter, but the associated type on it
+                        // We suggested constraining a type parameter, but the associated item on it
                         // was also not an exact match, so we also suggest changing it.
                         err.span_suggestion_verbose(
                             assoc_name.span,
@@ -258,16 +258,17 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
             }
         }
 
-        // If we still couldn't find any associated type, and only one associated type exists,
+        // If we still couldn't find any associated item, and only one associated item exists,
         // suggests using it.
         if let [candidate_name] = all_candidate_names.as_slice() {
-            // this should still compile, except on `#![feature(associated_type_defaults)]`
-            // where it could suggests `type A = Self::A`, thus recursing infinitely
-            let applicability = if tcx.features().associated_type_defaults {
-                Applicability::Unspecified
-            } else {
-                Applicability::MaybeIncorrect
-            };
+            // This should still compile, except on `#![feature(associated_type_defaults)]`
+            // where it could suggests `type A = Self::A`, thus recursing infinitely.
+            let applicability =
+                if assoc_kind == ty::AssocKind::Type && tcx.features().associated_type_defaults {
+                    Applicability::Unspecified
+                } else {
+                    Applicability::MaybeIncorrect
+                };
 
             err.sugg = Some(errors::AssocItemNotFoundSugg::Other {
                 span: assoc_name.span,
@@ -289,13 +290,13 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         assoc_kind: ty::AssocKind,
         ident: Ident,
         span: Span,
-        binding: Option<&super::ConvertedBinding<'_, 'tcx>>,
+        binding: Option<&hir::TypeBinding<'tcx>>,
     ) -> ErrorGuaranteed {
         let tcx = self.tcx();
 
         let bound_on_assoc_const_label = if let ty::AssocKind::Const = assoc_item.kind
             && let Some(binding) = binding
-            && let ConvertedBindingKind::Constraint(_) = binding.kind
+            && let hir::TypeBindingKind::Constraint { .. } = binding.kind
         {
             let lo = if binding.gen_args.span_ext.is_dummy() {
                 ident.span
@@ -309,25 +310,29 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
 
         // FIXME(associated_const_equality): This has quite a few false positives and negatives.
         let wrap_in_braces_sugg = if let Some(binding) = binding
-            && let ConvertedBindingKind::Equality(term) = binding.kind
-            && let ty::TermKind::Ty(ty) = term.node.unpack()
+            && let hir::TypeBindingKind::Equality { term: hir::Term::Ty(hir_ty) } = binding.kind
+            && let ty = self.ast_ty_to_ty(hir_ty)
             && (ty.is_enum() || ty.references_error())
             && tcx.features().associated_const_equality
         {
             Some(errors::AssocKindMismatchWrapInBracesSugg {
-                lo: term.span.shrink_to_lo(),
-                hi: term.span.shrink_to_hi(),
+                lo: hir_ty.span.shrink_to_lo(),
+                hi: hir_ty.span.shrink_to_hi(),
             })
         } else {
             None
         };
 
         // For equality bounds, we want to blame the term (RHS) instead of the item (LHS) since
-        // one can argue that that's more “untuitive” to the user.
+        // one can argue that that's more “intuitive” to the user.
         let (span, expected_because_label, expected, got) = if let Some(binding) = binding
-            && let ConvertedBindingKind::Equality(term) = binding.kind
+            && let hir::TypeBindingKind::Equality { term } = binding.kind
         {
-            (term.span, Some(ident.span), assoc_item.kind, assoc_kind)
+            let span = match term {
+                hir::Term::Ty(ty) => ty.span,
+                hir::Term::Const(ct) => tcx.def_span(ct.def_id),
+            };
+            (span, Some(ident.span), assoc_item.kind, assoc_kind)
         } else {
             (ident.span, None, assoc_kind, assoc_item.kind)
         };
diff --git a/compiler/rustc_hir_analysis/src/astconv/mod.rs b/compiler/rustc_hir_analysis/src/astconv/mod.rs
index 94c49453cdc..3ccf78567ed 100644
--- a/compiler/rustc_hir_analysis/src/astconv/mod.rs
+++ b/compiler/rustc_hir_analysis/src/astconv/mod.rs
@@ -35,7 +35,6 @@ use rustc_middle::ty::{
 };
 use rustc_session::lint::builtin::AMBIGUOUS_ASSOCIATED_ITEMS;
 use rustc_span::edit_distance::find_best_match_for_name;
-use rustc_span::source_map::{respan, Spanned};
 use rustc_span::symbol::{kw, Ident, Symbol};
 use rustc_span::{sym, BytePos, Span, DUMMY_SP};
 use rustc_target::spec::abi;
@@ -151,21 +150,6 @@ pub trait AstConv<'tcx> {
     fn infcx(&self) -> Option<&InferCtxt<'tcx>>;
 }
 
-#[derive(Debug)]
-struct ConvertedBinding<'a, 'tcx> {
-    hir_id: hir::HirId,
-    item_name: Ident,
-    kind: ConvertedBindingKind<'a, 'tcx>,
-    gen_args: &'tcx GenericArgs<'tcx>,
-    span: Span,
-}
-
-#[derive(Debug)]
-enum ConvertedBindingKind<'a, 'tcx> {
-    Equality(Spanned<ty::Term<'tcx>>),
-    Constraint(&'a [hir::GenericBound<'tcx>]),
-}
-
 /// New-typed boolean indicating whether explicit late-bound lifetimes
 /// are present in a set of generic arguments.
 ///
@@ -316,7 +300,9 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
     /// Given the type/lifetime/const arguments provided to some path (along with
     /// an implicit `Self`, if this is a trait reference), returns the complete
     /// set of generic arguments. This may involve applying defaulted type parameters.
-    /// Constraints on associated types are created from `create_assoc_bindings_for_generic_args`.
+    ///
+    /// Constraints on associated types are not converted here but
+    /// separately in `add_predicates_for_ast_type_binding`.
     ///
     /// Example:
     ///
@@ -329,8 +315,8 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
     /// 2. The path in question is the path to the trait `std::ops::Index`,
     ///    which will have been resolved to a `def_id`
     /// 3. The `generic_args` contains info on the `<...>` contents. The `usize` type
-    ///    parameters are returned in the `GenericArgsRef`, the associated type bindings like
-    ///    `Output = u32` are returned from `create_assoc_bindings_for_generic_args`.
+    ///    parameters are returned in the `GenericArgsRef`
+    /// 4. Associated type bindings like `Output = u32` are contained in `generic_args.bindings`.
     ///
     /// Note that the type listing given here is *exactly* what the user provided.
     ///
@@ -591,52 +577,6 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         (args, arg_count)
     }
 
-    fn create_assoc_bindings_for_generic_args<'a>(
-        &self,
-        generic_args: &'a hir::GenericArgs<'tcx>,
-    ) -> Vec<ConvertedBinding<'a, 'tcx>> {
-        // Convert associated-type bindings or constraints into a separate vector.
-        // Example: Given this:
-        //
-        //     T: Iterator<Item = u32>
-        //
-        // The `T` is passed in as a self-type; the `Item = u32` is
-        // not a "type parameter" of the `Iterator` trait, but rather
-        // a restriction on `<T as Iterator>::Item`, so it is passed
-        // back separately.
-        let assoc_bindings = generic_args
-            .bindings
-            .iter()
-            .map(|binding| {
-                let kind = match &binding.kind {
-                    hir::TypeBindingKind::Equality { term } => match term {
-                        hir::Term::Ty(ty) => ConvertedBindingKind::Equality(respan(
-                            ty.span,
-                            self.ast_ty_to_ty(ty).into(),
-                        )),
-                        hir::Term::Const(c) => {
-                            let span = self.tcx().def_span(c.def_id);
-                            let c = Const::from_anon_const(self.tcx(), c.def_id);
-                            ConvertedBindingKind::Equality(respan(span, c.into()))
-                        }
-                    },
-                    hir::TypeBindingKind::Constraint { bounds } => {
-                        ConvertedBindingKind::Constraint(bounds)
-                    }
-                };
-                ConvertedBinding {
-                    hir_id: binding.hir_id,
-                    item_name: binding.ident,
-                    kind,
-                    gen_args: binding.gen_args,
-                    span: binding.span,
-                }
-            })
-            .collect();
-
-        assoc_bindings
-    }
-
     pub fn create_args_for_associated_item(
         &self,
         span: Span,
@@ -742,18 +682,16 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         let bound_vars = tcx.late_bound_vars(trait_ref.hir_ref_id);
         debug!(?bound_vars);
 
-        let assoc_bindings = self.create_assoc_bindings_for_generic_args(args);
-
         let poly_trait_ref = ty::Binder::bind_with_vars(
             ty::TraitRef::new(tcx, trait_def_id, generic_args),
             bound_vars,
         );
 
-        debug!(?poly_trait_ref, ?assoc_bindings);
+        debug!(?poly_trait_ref);
         bounds.push_trait_bound(tcx, poly_trait_ref, span, polarity);
 
         let mut dup_bindings = FxIndexMap::default();
-        for binding in &assoc_bindings {
+        for binding in args.bindings {
             // Don't register additional associated type bounds for negative bounds,
             // since we should have emitten an error for them earlier, and they will
             // not be well-formed!
@@ -1029,7 +967,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         assoc_kind: ty::AssocKind,
         assoc_name: Ident,
         span: Span,
-        binding: Option<&ConvertedBinding<'_, 'tcx>>,
+        binding: Option<&hir::TypeBinding<'tcx>>,
     ) -> Result<ty::PolyTraitRef<'tcx>, ErrorGuaranteed>
     where
         I: Iterator<Item = ty::PolyTraitRef<'tcx>>,
@@ -1069,7 +1007,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
             // Provide a more specific error code index entry for equality bindings.
             err.code(
                 if let Some(binding) = binding
-                    && let ConvertedBindingKind::Equality(_) = binding.kind
+                    && let hir::TypeBindingKind::Equality { .. } = binding.kind
                 {
                     E0222
                 } else {
@@ -1094,16 +1032,21 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                     );
                     if let Some(binding) = binding {
                         match binding.kind {
-                            ConvertedBindingKind::Equality(term) => {
+                            hir::TypeBindingKind::Equality { term } => {
+                                let term: ty::Term<'_> = match term {
+                                    hir::Term::Ty(ty) => self.ast_ty_to_ty(ty).into(),
+                                    hir::Term::Const(ct) => {
+                                        ty::Const::from_anon_const(tcx, ct.def_id).into()
+                                    }
+                                };
                                 // FIXME(#97583): This isn't syntactically well-formed!
                                 where_bounds.push(format!(
                                     "        T: {trait}::{assoc_name} = {term}",
                                     trait = bound.print_only_trait_path(),
-                                    term = term.node,
                                 ));
                             }
                             // FIXME: Provide a suggestion.
-                            ConvertedBindingKind::Constraint(_bounds) => {}
+                            hir::TypeBindingKind::Constraint { bounds: _ } => {}
                         }
                     } else {
                         err.span_suggestion_verbose(
diff --git a/compiler/rustc_hir_analysis/src/check/check.rs b/compiler/rustc_hir_analysis/src/check/check.rs
index 1410273e3bc..2c367b15df2 100644
--- a/compiler/rustc_hir_analysis/src/check/check.rs
+++ b/compiler/rustc_hir_analysis/src/check/check.rs
@@ -129,17 +129,20 @@ fn check_unnamed_fields(tcx: TyCtxt<'_>, def: ty::AdtDef<'_>) {
     for field in variant.fields.iter().filter(|f| f.is_unnamed()) {
         let field_ty = tcx.type_of(field.did).instantiate_identity();
         if let Some(adt) = field_ty.ty_adt_def()
-            && !adt.is_anonymous()
-            && !adt.repr().c()
+            && !adt.is_enum()
         {
-            let field_ty_span = tcx.def_span(adt.did());
-            tcx.dcx().emit_err(errors::UnnamedFieldsRepr::FieldMissingReprC {
-                span: tcx.def_span(field.did),
-                field_ty_span,
-                field_ty,
-                field_adt_kind: adt.descr(),
-                sugg_span: field_ty_span.shrink_to_lo(),
-            });
+            if !adt.is_anonymous() && !adt.repr().c() {
+                let field_ty_span = tcx.def_span(adt.did());
+                tcx.dcx().emit_err(errors::UnnamedFieldsRepr::FieldMissingReprC {
+                    span: tcx.def_span(field.did),
+                    field_ty_span,
+                    field_ty,
+                    field_adt_kind: adt.descr(),
+                    sugg_span: field_ty_span.shrink_to_lo(),
+                });
+            }
+        } else {
+            tcx.dcx().emit_err(errors::InvalidUnnamedFieldTy { span: tcx.def_span(field.did) });
         }
     }
 }
diff --git a/compiler/rustc_hir_analysis/src/collect.rs b/compiler/rustc_hir_analysis/src/collect.rs
index 43f0af5bd1d..a5ef1490bce 100644
--- a/compiler/rustc_hir_analysis/src/collect.rs
+++ b/compiler/rustc_hir_analysis/src/collect.rs
@@ -943,7 +943,15 @@ impl<'tcx> FieldUniquenessCheckContext<'tcx> {
                 }
             }
             hir::TyKind::Path(hir::QPath::Resolved(_, hir::Path { res, .. })) => {
-                self.check_field_in_nested_adt(self.tcx.adt_def(res.def_id()), field.span);
+                // If this is a direct path to an ADT, we can check it
+                // If this is a type alias or non-ADT, `check_unnamed_fields` should verify it
+                if let Some(def_id) = res.opt_def_id()
+                    && let Some(local) = def_id.as_local()
+                    && let Node::Item(item) = self.tcx.hir_node_by_def_id(local)
+                    && item.is_adt()
+                {
+                    self.check_field_in_nested_adt(self.tcx.adt_def(def_id), field.span);
+                }
             }
             // Abort due to errors (there must be an error if an unnamed field
             //  has any type kind other than an anonymous adt or a named adt)
diff --git a/compiler/rustc_hir_analysis/src/errors.rs b/compiler/rustc_hir_analysis/src/errors.rs
index 6a505b96197..3bd7687a544 100644
--- a/compiler/rustc_hir_analysis/src/errors.rs
+++ b/compiler/rustc_hir_analysis/src/errors.rs
@@ -662,6 +662,13 @@ pub(crate) struct InvalidUnionField {
 }
 
 #[derive(Diagnostic)]
+#[diag(hir_analysis_invalid_unnamed_field_ty)]
+pub struct InvalidUnnamedFieldTy {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
 #[diag(hir_analysis_return_type_notation_on_non_rpitit)]
 pub(crate) struct ReturnTypeNotationOnNonRpitit<'tcx> {
     #[primary_span]
diff --git a/compiler/rustc_hir_typeck/src/errors.rs b/compiler/rustc_hir_typeck/src/errors.rs
index 10e12d01b1f..1af0b75bd23 100644
--- a/compiler/rustc_hir_typeck/src/errors.rs
+++ b/compiler/rustc_hir_typeck/src/errors.rs
@@ -293,7 +293,7 @@ pub enum HelpUseLatestEdition {
 impl HelpUseLatestEdition {
     pub fn new() -> Self {
         let edition = LATEST_STABLE_EDITION;
-        if std::env::var_os("CARGO").is_some() {
+        if rustc_session::utils::was_invoked_from_cargo() {
             Self::Cargo { edition }
         } else {
             Self::Standalone { edition }
diff --git a/compiler/rustc_incremental/src/persist/fs.rs b/compiler/rustc_incremental/src/persist/fs.rs
index 2578f284dee..23d29916922 100644
--- a/compiler/rustc_incremental/src/persist/fs.rs
+++ b/compiler/rustc_incremental/src/persist/fs.rs
@@ -492,7 +492,7 @@ fn lock_directory(
                 lock_err,
                 session_dir,
                 is_unsupported_lock,
-                is_cargo: std::env::var_os("CARGO").map(|_| ()),
+                is_cargo: rustc_session::utils::was_invoked_from_cargo().then_some(()),
             }))
         }
     }
diff --git a/compiler/rustc_lint/src/context/diagnostics.rs b/compiler/rustc_lint/src/context/diagnostics.rs
index 0fa61c5d87e..5af2b6daec1 100644
--- a/compiler/rustc_lint/src/context/diagnostics.rs
+++ b/compiler/rustc_lint/src/context/diagnostics.rs
@@ -205,7 +205,7 @@ pub(super) fn builtin(
                 Vec::new()
             };
 
-            let is_from_cargo = std::env::var_os("CARGO").is_some();
+            let is_from_cargo = rustc_session::utils::was_invoked_from_cargo();
             let mut is_feature_cfg = name == sym::feature;
 
             if is_feature_cfg && is_from_cargo {
@@ -340,7 +340,7 @@ pub(super) fn builtin(
                 .copied()
                 .flatten()
                 .collect();
-            let is_from_cargo = std::env::var_os("CARGO").is_some();
+            let is_from_cargo = rustc_session::utils::was_invoked_from_cargo();
 
             // Show the full list if all possible values for a given name, but don't do it
             // for names as the possibilities could be very long
diff --git a/compiler/rustc_parse/src/errors.rs b/compiler/rustc_parse/src/errors.rs
index 3c3a8d6fbb9..674f7218ea6 100644
--- a/compiler/rustc_parse/src/errors.rs
+++ b/compiler/rustc_parse/src/errors.rs
@@ -2545,7 +2545,7 @@ pub enum HelpUseLatestEdition {
 impl HelpUseLatestEdition {
     pub fn new() -> Self {
         let edition = LATEST_STABLE_EDITION;
-        if std::env::var_os("CARGO").is_some() {
+        if rustc_session::utils::was_invoked_from_cargo() {
             Self::Cargo { edition }
         } else {
             Self::Standalone { edition }
diff --git a/compiler/rustc_session/src/utils.rs b/compiler/rustc_session/src/utils.rs
index f76c69af526..50ebbdccf67 100644
--- a/compiler/rustc_session/src/utils.rs
+++ b/compiler/rustc_session/src/utils.rs
@@ -1,7 +1,10 @@
 use crate::session::Session;
 use rustc_data_structures::profiling::VerboseTimingGuard;
 use rustc_fs_util::try_canonicalize;
-use std::path::{Path, PathBuf};
+use std::{
+    path::{Path, PathBuf},
+    sync::OnceLock,
+};
 
 impl Session {
     pub fn timer(&self, what: &'static str) -> VerboseTimingGuard<'_> {
@@ -158,3 +161,18 @@ pub fn extra_compiler_flags() -> Option<(Vec<String>, bool)> {
 
     if !result.is_empty() { Some((result, excluded_cargo_defaults)) } else { None }
 }
+
+/// Returns whenever rustc was launched by Cargo as opposed to another build system.
+///
+/// To be used in diagnostics to avoid printing Cargo specific suggestions to other
+/// build systems (like Bazel, Buck2, Makefile, ...).
+pub fn was_invoked_from_cargo() -> bool {
+    static FROM_CARGO: OnceLock<bool> = OnceLock::new();
+
+    // To be able to detect Cargo, we use the simplest and least intrusive
+    // way: we check whenever the `CARGO_CRATE_NAME` env is set.
+    //
+    // Note that it is common in Makefiles to define the `CARGO` env even
+    // though we may not have been called by Cargo, so we avoid using it.
+    *FROM_CARGO.get_or_init(|| std::env::var_os("CARGO_CRATE_NAME").is_some())
+}
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 0472981086e..2d85f84f480 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
@@ -3689,6 +3689,24 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         if let Node::Expr(expr) = tcx.hir_node(arg_hir_id)
             && let Some(typeck_results) = &self.typeck_results
         {
+            if let hir::Expr { kind: hir::ExprKind::MethodCall(_, rcvr, _, _), .. } = expr
+                && let Some(ty) = typeck_results.node_type_opt(rcvr.hir_id)
+                && let Some(failed_pred) = failed_pred.to_opt_poly_trait_pred()
+                && let pred = failed_pred.map_bound(|pred| pred.with_self_ty(tcx, ty))
+                && self.predicate_must_hold_modulo_regions(&Obligation::misc(
+                    tcx, expr.span, body_id, param_env, pred,
+                ))
+            {
+                err.span_suggestion_verbose(
+                    expr.span.with_lo(rcvr.span.hi()),
+                    format!(
+                        "consider removing this method call, as the receiver has type `{ty}` and \
+                         `{pred}` trivially holds",
+                    ),
+                    "",
+                    Applicability::MaybeIncorrect,
+                );
+            }
             if let hir::Expr { kind: hir::ExprKind::Block(block, _), .. } = expr {
                 let inner_expr = expr.peel_blocks();
                 let ty = typeck_results
@@ -3824,7 +3842,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
             }
         }
 
-        if let Node::Expr(expr) = tcx.hir_node(call_hir_id) {
+        if let Node::Expr(expr) = call_node {
             if let hir::ExprKind::Call(hir::Expr { span, .. }, _)
             | hir::ExprKind::MethodCall(
                 hir::PathSegment { ident: Ident { span, .. }, .. },