Merge pull request swiftlang#72433 from DougGregor/demangle-noncopyable-ext

[Demangle-to-type] Properly match extensions of conditionally-copyable types

Author: DougGregor

lib/AST/ASTDemangler.cpp

@@ -1282,9 +1282,20 @@ ASTBuilder::findDeclContext(NodePointer node) {
         continue;
       }
 
-      if (ext->getGenericSignature().getCanonicalSignature() == genericSig) {
+      auto extSig = ext->getGenericSignature().getCanonicalSignature();
+      if (extSig == genericSig) {
         return ext;
       }
+
+      // If the extension mangling doesn't include a generic signature, it
+      // might be because the nominal type suppresses conformance.
+      if (!genericSig) {
+        SmallVector<Requirement, 2> requirements;
+        SmallVector<InverseRequirement, 2> inverses;
+        extSig->getRequirementsWithInverses(requirements, inverses);
+        if (requirements.empty())
+          return ext;
+      }
     }
 
     return nullptr;

test/IRGen/mangling_inverse_generics_evolution.swift

@@ -76,3 +76,13 @@ open class ManagedBuffer<Header, Element: ~Copyable> {
     fatalError("boom")
   }
 }
+
+extension UnsafePointer {
+  struct AtomicRepresentation { }
+}
+
+// CHECK: $sSP4testE20AtomicRepresentationVySi_GD
+func useAtomicRepresentation() {
+  let x = UnsafePointer<Int>.AtomicRepresentation()
+  print(x)
+}