[Clang] fix overload resolution for object parameters with top-level cv-qualifiers in member functions

clang/docs/ReleaseNotes.rst

@@ -455,6 +455,7 @@ Bug Fixes to C++ Support
   containing outer unexpanded parameters were not correctly expanded. (#GH101754)
 - Fixed a bug in constraint expression comparison where the ``sizeof...`` expression was not handled properly
   in certain friend declarations. (#GH93099)
+- Fixed overload handling for object parameters with top-level cv-qualifiers in explicit member functions (#GH100394)
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^

clang/lib/Sema/SemaOverload.cpp

@@ -1511,6 +1511,9 @@ static bool IsOverloadOrOverrideImpl(Sema &SemaRef, FunctionDecl *New,
       auto NewObjectType = New->getFunctionObjectParameterReferenceType();
       auto OldObjectType = Old->getFunctionObjectParameterReferenceType();
 
+      if (NewObjectType.isConstQualified() != OldObjectType.isConstQualified())
+        return false;
+
       auto IsImplicitWithNoRefQual = [](const CXXMethodDecl *F) {
         return F->getRefQualifier() == RQ_None &&
                !F->isExplicitObjectMemberFunction();

clang/test/SemaCXX/cxx2b-deducing-this.cpp

@@ -1073,3 +1073,10 @@ int main() {
   return foo[]; // expected-error {{no viable overloaded operator[] for type 'Foo'}}
 }
 }
+
+namespace GH100394 {
+struct C {
+  void f(this const C);
+  void f() const ;      // ok
+};
+}