From 10a0316219908628d2ce656963b14ee98bd7ce74 Mon Sep 17 00:00:00 2001
From: Fariborz Jahanian <fjahanian@apple.com>
Date: Mon, 27 Jan 2014 22:27:43 +0000
Subject: [PATCH] ObjectiveC. Fixes a bug in recognition of an ivar backing a
 property resulting in bogus warning. // rdar://15890251

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@200254 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Sema/SemaDeclObjC.cpp                   | 17 +++++++-------
 test/SemaObjC/unused-backing-ivar-warning.m | 25 +++++++++++++++++++++
 2 files changed, 33 insertions(+), 9 deletions(-)

diff --git a/lib/Sema/SemaDeclObjC.cpp b/lib/Sema/SemaDeclObjC.cpp
index 7d023e1d40..c91ce37711 100644
--- a/lib/Sema/SemaDeclObjC.cpp
+++ b/lib/Sema/SemaDeclObjC.cpp
@@ -3449,8 +3449,14 @@ Sema::GetIvarBackingPropertyAccessor(const ObjCMethodDecl *Method,
   if (!Method || !Method->isPropertyAccessor())
     return 0;
   if ((PDecl = Method->findPropertyDecl()))
-    return PDecl->getPropertyIvarDecl();
-
+    if (ObjCIvarDecl *IV = PDecl->getPropertyIvarDecl()) {
+      // property backing ivar must belong to property's class
+      // or be a private ivar in class's implementation.
+      // FIXME. fix the const-ness issue.
+      IV = const_cast<ObjCInterfaceDecl *>(IDecl)->lookupInstanceVariable(
+                                                        IV->getIdentifier());
+      return IV;
+    }
   return 0;
 }
 
@@ -3509,13 +3515,6 @@ void Sema::DiagnoseUnusedBackingIvarInAccessor(Scope *S,
     const ObjCIvarDecl *IV = GetIvarBackingPropertyAccessor(CurMethod, PDecl);
     if (!IV)
       continue;
-    // Property declared as @dynamic must be ignored.
-    if (ObjCPropertyImplDecl *PropertyImpDecl =
-          Context.getObjCPropertyImplDeclForPropertyDecl(PDecl, ImplD))
-      if (PropertyImpDecl->getPropertyImplementation() ==
-            ObjCPropertyImplDecl::Dynamic)
-        continue;
-      
 
     UnusedBackingIvarChecker Checker(*this, CurMethod, IV);
     Checker.TraverseStmt(CurMethod->getBody());
diff --git a/test/SemaObjC/unused-backing-ivar-warning.m b/test/SemaObjC/unused-backing-ivar-warning.m
index 59fbc85d60..390d554e14 100644
--- a/test/SemaObjC/unused-backing-ivar-warning.m
+++ b/test/SemaObjC/unused-backing-ivar-warning.m
@@ -170,3 +170,28 @@ typedef char BOOL;
     return 0;
 }
 @end
+
+// rdar://15890251
+@class NSURL;
+
+@protocol MCCIDURLProtocolDataProvider
+@required
+@property(strong, atomic, readonly) NSURL *cidURL;
+@end
+
+@interface UnrelatedClass : NSObject <MCCIDURLProtocolDataProvider>
+@end
+
+@implementation UnrelatedClass
+@synthesize cidURL = _cidURL;
+@end
+
+@interface MUIWebAttachmentController : NSObject <MCCIDURLProtocolDataProvider>
+@end
+
+
+@implementation MUIWebAttachmentController
+- (NSURL *)cidURL {
+    return 0;
+}
+@end
-- 
2.40.0