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

1 files changed, 6 insertions, 0 deletions

diff --git a/compiler/rustc_resolve/src/lib.rs b/compiler/rustc_resolve/src/lib.rs
index 6c0f2b89347..6b07bfdec67 100644
--- a/compiler/rustc_resolve/src/lib.rs
+++ b/compiler/rustc_resolve/src/lib.rs
@@ -1016,6 +1016,8 @@ pub struct Resolver<'a, 'tcx> {
     binding_parent_modules: FxHashMap<NameBinding<'a>, Module<'a>>,
 
     underscore_disambiguator: u32,
+    /// Disambiguator for anonymous adts.
+    empty_disambiguator: u32,
 
     /// Maps glob imports to the names of items actually imported.
     glob_map: FxHashMap<LocalDefId, FxHashSet<Symbol>>,
@@ -1367,6 +1369,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
             module_children: Default::default(),
             trait_map: NodeMap::default(),
             underscore_disambiguator: 0,
+            empty_disambiguator: 0,
             empty_module,
             module_map,
             block_map: Default::default(),
@@ -1734,6 +1737,9 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
         let disambiguator = if ident.name == kw::Underscore {
             self.underscore_disambiguator += 1;
             self.underscore_disambiguator
+        } else if ident.name == kw::Empty {
+            self.empty_disambiguator += 1;
+            self.empty_disambiguator
         } else {
             0
         };