Objective-C ARC. Do not warn about properties with both

IBOutlet and weak attributes when accessed being
unpredictably set to nil because usage of such properties
are always single threaded and its ivar cannot be set
to nil asynchronously. // rdar://15885642 

llvm-svn: 211132

clang/lib/Sema/ScopeInfo.cpp

@@ -158,8 +158,14 @@ void FunctionScopeInfo::markSafeWeakUse(const Expr *E) {
 
   // Has this weak object been seen before?
   FunctionScopeInfo::WeakObjectUseMap::iterator Uses;
-  if (const ObjCPropertyRefExpr *RefExpr = dyn_cast<ObjCPropertyRefExpr>(E))
-    Uses = WeakObjectUses.find(WeakObjectProfileTy(RefExpr));
+  if (const ObjCPropertyRefExpr *RefExpr = dyn_cast<ObjCPropertyRefExpr>(E)) {
+    if (isa<OpaqueValueExpr>(RefExpr->getBase()))
+     Uses = WeakObjectUses.find(WeakObjectProfileTy(RefExpr));
+    else {
+      markSafeWeakUse(RefExpr->getBase());
+      return;
+    }
+  }
   else if (const ObjCIvarRefExpr *IvarE = dyn_cast<ObjCIvarRefExpr>(E))
     Uses = WeakObjectUses.find(WeakObjectProfileTy(IvarE));
   else if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))

clang/lib/Sema/SemaExprObjC.cpp

@@ -2640,7 +2640,14 @@ ExprResult Sema::BuildInstanceMessage(Expr *Receiver,
   }
 
   if (getLangOpts().ObjCAutoRefCount) {
-    DiagnoseARCUseOfWeakReceiver(*this, Receiver);
+    // Do not warn about IBOutlet weak property receivers being set to null
+    // as this cannot asynchronously happen.
+    bool WarnWeakReceiver = true;
+    if (isImplicit && Method)
+      if (const ObjCPropertyDecl *PropertyDecl = Method->findPropertyDecl())
+        WarnWeakReceiver = !PropertyDecl->hasAttr<IBOutletAttr>();
+    if (WarnWeakReceiver)
+      DiagnoseARCUseOfWeakReceiver(*this, Receiver);
     
     // In ARC, annotate delegate init calls.
     if (Result->getMethodFamily() == OMF_init &&

clang/lib/Sema/SemaPseudoObject.cpp

@@ -542,7 +542,7 @@ bool ObjCPropertyOpBuilder::isWeakProperty() const {
   if (RefExpr->isExplicitProperty()) {
     const ObjCPropertyDecl *Prop = RefExpr->getExplicitProperty();
     if (Prop->getPropertyAttributes() & ObjCPropertyDecl::OBJC_PR_weak)
-      return true;
+      return !Prop->hasAttr<IBOutletAttr>();
 
     T = Prop->getType();
   } else if (Getter) {
@@ -816,13 +816,20 @@ ExprResult ObjCPropertyOpBuilder::buildRValueOperation(Expr *op) {
 
   // As a special case, if the method returns 'id', try to get
   // a better type from the property.
-  if (RefExpr->isExplicitProperty() && result.get()->isRValue() &&
-      result.get()->getType()->isObjCIdType()) {
+  if (RefExpr->isExplicitProperty() && result.get()->isRValue()) {
     QualType propType = RefExpr->getExplicitProperty()->getType();
-    if (const ObjCObjectPointerType *ptr
-          = propType->getAs<ObjCObjectPointerType>()) {
-      if (!ptr->isObjCIdType())
-        result = S.ImpCastExprToType(result.get(), propType, CK_BitCast);
+    if (result.get()->getType()->isObjCIdType()) {
+      if (const ObjCObjectPointerType *ptr
+            = propType->getAs<ObjCObjectPointerType>()) {
+        if (!ptr->isObjCIdType())
+          result = S.ImpCastExprToType(result.get(), propType, CK_BitCast);
+      }
+    }
+    if (S.getLangOpts().ObjCAutoRefCount) {
+      Qualifiers::ObjCLifetime LT = propType.getObjCLifetime();
+      if (LT == Qualifiers::OCL_Weak)
+        if (!S.Diags.isIgnored(diag::warn_arc_repeated_use_of_weak, RefExpr->getLocation()))
+              S.getCurFunction()->markSafeWeakUse(RefExpr);
     }
   }
 

clang/test/SemaObjC/iboutlet.m

@@ -1,5 +1,5 @@
-// RUN: %clang_cc1 -fsyntax-only -Wno-objc-root-class -verify %s
-// RUN: %clang_cc1 -x objective-c++ -fsyntax-only -Wno-objc-root-class -verify %s
+// RUN: %clang_cc1 -fsyntax-only -fobjc-arc -Wno-objc-root-class -Wreceiver-is-weak -Warc-repeated-use-of-weak -fobjc-runtime-has-weak -verify %s
+// RUN: %clang_cc1 -x objective-c++ -fsyntax-only -fobjc-arc -Wno-objc-root-class -Wreceiver-is-weak -Warc-repeated-use-of-weak -fobjc-runtime-has-weak -verify %s
 // rdar://11448209
 
 #define READONLY readonly
@@ -40,3 +40,15 @@
 @implementation RKTFHView
 @synthesize synthReadOnlyReadWrite=_synthReadOnlyReadWrite;
 @end
+
+// rdar://15885642
+@interface WeakOutlet 
+@property IBOutlet __weak WeakOutlet* WeakProp;
+@end
+
+WeakOutlet* func() {
+  __weak WeakOutlet* pwi;
+  pwi.WeakProp = (WeakOutlet*)0;
+  pwi.WeakProp = pwi.WeakProp;
+  return pwi.WeakProp;
+}