Auto merge of #115367 - frank-king:feature/unnamed-fields-hir, r=davidtwco

Lowering unnamed fields and anonymous adt

This implements #49804.

Goals:
- [x] lowering anonymous ADTs from AST to HIR
- [x] generating definitions of anonymous ADTs
- [x] uniqueness check of the unnamed fields
- [x] field projection of anonymous ADTs
- [x] `#[repr(C)]` check of the anonymous ADTs

Non-Goals (will be in the next PRs)
- capturing generic params for the anonymous ADTs from the parent ADT
- pattern matching of anonymous ADTs
- structural expressions of anonymous ADTs
- rustdoc support of anonymous ADTs

Author: bors

clippy_lints/src/dereference.rs

@@ -831,6 +831,7 @@ impl TyCoercionStability {
                 | TyKind::Typeof(..)
                 | TyKind::TraitObject(..)
                 | TyKind::InferDelegation(..)
+                | TyKind::AnonAdt(..)
                 | TyKind::Err(_) => Self::Reborrow,
             };
         }

clippy_utils/src/hir_utils.rs

@@ -515,6 +515,7 @@ impl HirEqInterExpr<'_, '_, '_> {
             (TyKind::Path(l), TyKind::Path(r)) => self.eq_qpath(l, r),
             (&TyKind::Tup(l), &TyKind::Tup(r)) => over(l, r, |l, r| self.eq_ty(l, r)),
             (&TyKind::Infer, &TyKind::Infer) => true,
+            (TyKind::AnonAdt(l_item_id), TyKind::AnonAdt(r_item_id)) => l_item_id == r_item_id,
             _ => false,
         }
     }
@@ -1108,7 +1109,7 @@ impl<'a, 'tcx> SpanlessHash<'a, 'tcx> {
             TyKind::Typeof(anon_const) => {
                 self.hash_body(anon_const.body);
             },
-            TyKind::Err(_) | TyKind::Infer | TyKind::Never | TyKind::InferDelegation(..) => {},
+            TyKind::Err(_) | TyKind::Infer | TyKind::Never | TyKind::InferDelegation(..) | TyKind::AnonAdt(_) => {},
         }
     }