From d32967402813e489ab567c9d271804f12f1cfcaa Mon Sep 17 00:00:00 2001
From: Fariborz Jahanian <fjahanian@apple.com>
Date: Thu, 19 Jun 2014 23:05:46 +0000
Subject: [PATCH] Objective-C qoi. When Objective-C pointer mismatches with a
 qualified-id type because pointer is object of a forward class declaration,
 include this info in a diagnostic note. // rdar://10751015

llvm-svn: 211324
---
 .../clang/Basic/DiagnosticSemaKinds.td        |  2 ++
 clang/lib/Sema/SemaExpr.cpp                   | 35 ++++++++++++++++---
 clang/test/SemaObjC/comptypes-legal.m         | 17 +++++++++
 3 files changed, 50 insertions(+), 4 deletions(-)

diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index b3a732e9e4cb..e6c8b9a34bd0 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -5491,6 +5491,8 @@ def err_typecheck_missing_return_type_incompatible : Error<
   "return type must match previous return type}0,1 when %select{block "
   "literal|lambda expression}2 has unspecified explicit return type">;
 
+def not_incomplete_class_and_qualified_id : Note<
+  "conformance of forward class %0 to protocol %1 can not be confirmed">;
 def warn_incompatible_qualified_id : Warning<
   "%select{%diff{assigning to $ from incompatible type $|"
   "assigning to type from incompatible type}0,1"
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 58a0c76769f2..2654c390ccf2 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);
diff --git a/clang/test/SemaObjC/comptypes-legal.m b/clang/test/SemaObjC/comptypes-legal.m
index d83d559ee64c..05f18977cc4e 100644
--- a/clang/test/SemaObjC/comptypes-legal.m
+++ b/clang/test/SemaObjC/comptypes-legal.m
@@ -35,3 +35,20 @@ void foo(void)
   // Since registerFunc: expects a Derived object as it's second argument, I don't know why this would be legal.
   [Derived registerFunc: ExternFunc];  // expected-warning{{incompatible pointer types sending 'NSObject *(NSObject *, NSObject *)' to parameter of type 'FuncSignature *'}}
 }
+
+// rdar://10751015
+@protocol NSCopying @end
+@interface I
+- (void) Meth : (id <NSCopying>)aKey; // expected-note {{passing argument to parameter 'aKey' here}}
+@end
+
+@class ForwarClass; // expected-note 3 {{conformance of forward class ForwarClass to protocol NSCopying can not be confirmed}}
+
+ForwarClass *Test10751015 (I* pi, ForwarClass *ns_forward) {
+
+  [pi Meth : ns_forward ]; // expected-warning {{sending 'ForwarClass *' to parameter of incompatible type 'id<NSCopying>'}}
+
+  id <NSCopying> id_ns = ns_forward; // expected-warning {{initializing 'id<NSCopying>' with an expression of incompatible type 'ForwarClass *'}}
+
+  return id_ns; // expected-warning {{returning 'id<NSCopying>' from a function with incompatible result type 'ForwarClass *'}}
+}