[Macros] Use the original attribute list when gathering possible macro-generated

names in the source lookup cache.

Invoking macro expansion while populating the source lookup cache is deliberately
avoided because it's prone to circularity. This applies to member attribute expansion,
which is requested via `getSemanticAttrs()`. Populating the auxiliary decl cache
should use the original attribute list, because declarations found via global lookup,
such as macro and operator decls, cannot have inferred attached macros.

Author: hborla

lib/AST/Module.cpp

@@ -350,7 +350,7 @@ void SourceLookupCache::populateAuxiliaryDeclCache() {
     // macro does not produce the requested name, so the only impact is possibly
     // expanding earlier than needed / unnecessarily looking in the top-level
     // auxiliary decl cache.
-    for (auto attrConst : decl->getSemanticAttrs().getAttributes<CustomAttr>()) {
+    for (auto attrConst : decl->getAttrs().getAttributes<CustomAttr>()) {
       auto *attr = const_cast<CustomAttr *>(attrConst);
       UnresolvedMacroReference macroRef(attr);
       auto macroName = macroRef.getMacroName().getBaseIdentifier();

test/Concurrency/global_actor_function_types.swift

@@ -386,3 +386,13 @@ func test_global_actor_mismatch() {
     let _: @MainActor () -> T = fn // expected-error{{cannot convert value actor-isolated to 'GA' to specified type actor-isolated to 'MainActor'}}
   }
 }
+
+struct GlobalType {}
+
+@_Concurrency.MainActor
+extension global_actor_function_types.GlobalType {
+  @_Concurrency.MainActor static func ==(
+    lhs: global_actor_function_types.GlobalType,
+    rhs: global_actor_function_types.GlobalType
+  ) -> Bool { true }
+}