Objective-C diagnostics: isObjCNSObjectType should check through AttributedType.

For the following example:
typedef __attribute__((NSObject)) CGColorRef ColorAttrRef;
@property (strong, nullable) ColorAttrRef color;
The property type should be ObjC NSObject type and the compiler should not emit
error: property with 'retain (or strong)' attribute must be of object type

rdar://problem/27747154


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@278742 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 11 insertions, 3 deletions

diff --git a/lib/AST/Type.cpp b/lib/AST/Type.cpp
index 68e1fc09b8..4c1d4ec540 100644
--- a/lib/AST/Type.cpp
+++ b/lib/AST/Type.cpp
@@ -3686,10 +3686,18 @@ bool Type::isObjCARCImplicitlyUnretainedType() const {
 }
 
 bool Type::isObjCNSObjectType() const {
-  if (const TypedefType *typedefType = dyn_cast<TypedefType>(this))
-    return typedefType->getDecl()->hasAttr<ObjCNSObjectAttr>();
-  return false;
+  const Type *cur = this;
+  while (true) {
+    if (const TypedefType *typedefType = dyn_cast<TypedefType>(cur))
+      return typedefType->getDecl()->hasAttr<ObjCNSObjectAttr>();
+
+    // Single-step desugar until we run out of sugar.
+    QualType next = cur->getLocallyUnqualifiedSingleStepDesugaredType();
+    if (next.getTypePtr() == cur) return false;
+    cur = next.getTypePtr();
+  }
 }
+
 bool Type::isObjCIndependentClassType() const {
   if (const TypedefType *typedefType = dyn_cast<TypedefType>(this))
     return typedefType->getDecl()->hasAttr<ObjCIndependentClassAttr>();