1 files changed, 31 insertions, 4 deletions

diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 58a0c76769f..2654c390ccf 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -10832,6 +10832,8 @@ bool Sema::DiagnoseAssignmentResult(AssignConvertType ConvTy,
   ConversionFixItGenerator ConvHints;
   bool MayHaveConvFixit = false;
   bool MayHaveFunctionDiff = false;
+  const ObjCInterfaceDecl *IFace = nullptr;
+  const ObjCProtocolDecl *PDecl = nullptr;
 
   switch (ConvTy) {
   case Compatible:
@@ -10913,11 +10915,32 @@ bool Sema::DiagnoseAssignmentResult(AssignConvertType ConvTy,
   case IncompatibleBlockPointer:
     DiagKind = diag::err_typecheck_convert_incompatible_block_pointer;
     break;
-  case IncompatibleObjCQualifiedId:
-    // FIXME: Diagnose the problem in ObjCQualifiedIdTypesAreCompatible, since
-    // it can give a more specific diagnostic.
+  case IncompatibleObjCQualifiedId: {
+    if (SrcType->isObjCQualifiedIdType()) {
+      const ObjCObjectPointerType *srcOPT =
+                SrcType->getAs<ObjCObjectPointerType>();
+      for (auto *srcProto : srcOPT->quals()) {
+        PDecl = srcProto;
+        break;
+      }
+      if (const ObjCInterfaceType *IFaceT =
+            DstType->getAs<ObjCObjectPointerType>()->getInterfaceType())
+        IFace = IFaceT->getDecl();
+    }
+    else if (DstType->isObjCQualifiedIdType()) {
+      const ObjCObjectPointerType *dstOPT =
+        DstType->getAs<ObjCObjectPointerType>();
+      for (auto *dstProto : dstOPT->quals()) {
+        PDecl = dstProto;
+        break;
+      }
+      if (const ObjCInterfaceType *IFaceT =
+            SrcType->getAs<ObjCObjectPointerType>()->getInterfaceType())
+        IFace = IFaceT->getDecl();
+    }
     DiagKind = diag::warn_incompatible_qualified_id;
     break;
+  }
   case IncompatibleVectors:
     DiagKind = diag::warn_incompatible_vectors;
     break;
@@ -10975,7 +10998,11 @@ bool Sema::DiagnoseAssignmentResult(AssignConvertType ConvTy,
     HandleFunctionTypeMismatch(FDiag, SecondType, FirstType);
 
   Diag(Loc, FDiag);
-
+  if (DiagKind == diag::warn_incompatible_qualified_id &&
+      PDecl && IFace && !IFace->hasDefinition())
+      Diag(IFace->getLocation(), diag::not_incomplete_class_and_qualified_id)
+        << IFace->getName() << PDecl->getName();
+    
   if (SecondType == Context.OverloadTy)
     NoteAllOverloadCandidates(OverloadExpr::find(SrcExpr).Expression,
                               FirstType);