Introduce `DefPathData::AnonAssocTy`.

PR #137977 changed `DefPathData::TypeNs` to contain `Option<Symbol>` to
account for RPITIT assoc types being anonymous. This commit changes it
back to `Symbol` and gives anonymous assoc types their own variant. It
makes things a bit nicer overall.

1 files changed, 10 insertions, 5 deletions

diff --git a/compiler/rustc_hir/src/def.rs b/compiler/rustc_hir/src/def.rs
index dc00b52a593..9372ab532bf 100644
--- a/compiler/rustc_hir/src/def.rs
+++ b/compiler/rustc_hir/src/def.rs
@@ -267,11 +267,16 @@ impl DefKind {
             | DefKind::ForeignTy
             | DefKind::TraitAlias
             | DefKind::TyParam
-            | DefKind::ExternCrate => DefPathData::TypeNs(Some(name.unwrap())),
-
-            // An associated type names will be missing for an RPITIT. It will
-            // later be given a name with `synthetic` in it, if necessary.
-            DefKind::AssocTy => DefPathData::TypeNs(name),
+            | DefKind::ExternCrate => DefPathData::TypeNs(name.unwrap()),
+
+            // An associated type name will be missing for an RPITIT.
+            DefKind::AssocTy => {
+                if let Some(name) = name {
+                    DefPathData::TypeNs(name)
+                } else {
+                    DefPathData::AnonAssocTy
+                }
+            }
 
             // It's not exactly an anon const, but wrt DefPathData, there
             // is no difference.