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

5 files changed, 20 insertions, 3 deletions

diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs
index 89977934cde..0b705df2a60 100644
--- a/src/librustdoc/clean/mod.rs
+++ b/src/librustdoc/clean/mod.rs
@@ -1892,6 +1892,9 @@ pub(crate) fn clean_ty<'tcx>(ty: &hir::Ty<'tcx>, cx: &mut DocContext<'tcx>) -> T
         TyKind::BareFn(barefn) => BareFunction(Box::new(clean_bare_fn_ty(barefn, cx))),
         // Rustdoc handles `TyKind::Err`s by turning them into `Type::Infer`s.
         TyKind::Infer | TyKind::Err(_) | TyKind::Typeof(..) | TyKind::InferDelegation(..) => Infer,
+        TyKind::AnonAdt(..) => {
+            unimplemented!("Anonymous structs or unions are not supported yet")
+        }
     }
 }
 
diff --git a/src/tools/clippy/clippy_lints/src/dereference.rs b/src/tools/clippy/clippy_lints/src/dereference.rs
index cdbb52f497b..0ddfeaa0ae0 100644
--- a/src/tools/clippy/clippy_lints/src/dereference.rs
+++ b/src/tools/clippy/clippy_lints/src/dereference.rs
@@ -831,6 +831,7 @@ impl TyCoercionStability {
                 | TyKind::Typeof(..)
                 | TyKind::TraitObject(..)
                 | TyKind::InferDelegation(..)
+                | TyKind::AnonAdt(..)
                 | TyKind::Err(_) => Self::Reborrow,
             };
         }
diff --git a/src/tools/clippy/clippy_utils/src/hir_utils.rs b/src/tools/clippy/clippy_utils/src/hir_utils.rs
index 4fa93ad23c3..d50332e82da 100644
--- a/src/tools/clippy/clippy_utils/src/hir_utils.rs
+++ b/src/tools/clippy/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(_) => {},
         }
     }
 
diff --git a/src/tools/rustfmt/src/types.rs b/src/tools/rustfmt/src/types.rs
index cd2582e66be..aaef80f4aef 100644
--- a/src/tools/rustfmt/src/types.rs
+++ b/src/tools/rustfmt/src/types.rs
@@ -806,8 +806,8 @@ impl Rewrite for ast::Ty {
             ast::TyKind::Tup(ref items) => {
                 rewrite_tuple(context, items.iter(), self.span, shape, items.len() == 1)
             }
-            ast::TyKind::AnonStruct(_) => Some(context.snippet(self.span).to_owned()),
-            ast::TyKind::AnonUnion(_) => Some(context.snippet(self.span).to_owned()),
+            ast::TyKind::AnonStruct(..) => Some(context.snippet(self.span).to_owned()),
+            ast::TyKind::AnonUnion(..) => Some(context.snippet(self.span).to_owned()),
             ast::TyKind::Path(ref q_self, ref path) => {
                 rewrite_path(context, PathContext::Type, q_self, path, shape)
             }
diff --git a/src/tools/rustfmt/tests/target/anonymous-types.rs b/src/tools/rustfmt/tests/target/anonymous-types.rs
index 8e08c314ed1..e8c2d83878c 100644
--- a/src/tools/rustfmt/tests/target/anonymous-types.rs
+++ b/src/tools/rustfmt/tests/target/anonymous-types.rs
@@ -16,4 +16,16 @@ struct Foo {
     e: f32,
 }
 
+// Test for https://github.com/rust-lang/rust/issues/117942
+struct Foo {
+    _: union  {
+        #[rustfmt::skip]
+    f: String,
+    },
+    #[rustfmt::skip]
+    _: struct {
+    g: i32,
+    },
+}
+
 fn main() {}