r318552 - [ObjC][ARC] Honor noescape attribute for -Warc-retain-cycles

[Alex Lorenz via cfe-commits]

Author: arphaman
Date: Fri Nov 17 12:44:25 2017
New Revision: 318552

URL: http://llvm.org/viewvc/llvm-project?rev=318552&view=rev
Log:
[ObjC][ARC] Honor noescape attribute for -Warc-retain-cycles

rdar://35409566

Differential Revision: https://reviews.llvm.org/D40141

Modified:
    cfe/trunk/lib/Sema/SemaChecking.cpp
    cfe/trunk/test/SemaObjC/warn-retain-cycle.m

Modified: cfe/trunk/lib/Sema/SemaChecking.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaChecking.cpp?rev=318552&r1=318551&r2=318552&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaChecking.cpp (original)
+++ cfe/trunk/lib/Sema/SemaChecking.cpp Fri Nov 17 12:44:25 2017
@@ -11652,9 +11652,15 @@ void Sema::checkRetainCycles(ObjCMessage
   }
 
   // Check whether the receiver is captured by any of the arguments.
-  for (unsigned i = 0, e = msg->getNumArgs(); i != e; ++i)
-    if (Expr *capturer = findCapturingExpr(*this, msg->getArg(i), owner))
+  const ObjCMethodDecl *MD = msg->getMethodDecl();
+  for (unsigned i = 0, e = msg->getNumArgs(); i != e; ++i) {
+    if (Expr *capturer = findCapturingExpr(*this, msg->getArg(i), owner)) {
+      // noescape blocks should not be retained by the method.
+      if (MD && MD->parameters()[i]->hasAttr<NoEscapeAttr>())
+        continue;
       return diagnoseRetainCycle(*this, capturer, owner);
+    }
+  }
 }
 
 /// Check a property assign to see if it's likely to cause a retain cycle.

Modified: cfe/trunk/test/SemaObjC/warn-retain-cycle.m
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaObjC/warn-retain-cycle.m?rev=318552&r1=318551&r2=318552&view=diff
==============================================================================
--- cfe/trunk/test/SemaObjC/warn-retain-cycle.m (original)
+++ cfe/trunk/test/SemaObjC/warn-retain-cycle.m Fri Nov 17 12:44:25 2017
@@ -198,3 +198,15 @@ __block void(^myBlock)(void) = ^{
    };
 
 }
+
+typedef void (^a_block_t)(void);
+
+ at interface HonorNoEscape
+- (void)addStuffUsingBlock:(__attribute__((noescape)) a_block_t)block;
+ at end
+
+void testNoEscape(HonorNoEscape *obj) {
+  [obj addStuffUsingBlock:^{
+    (void)obj; // ok.
+  }];
+}