[arcmt] Allow -retain of an __unsafe_unretained receiver if the result gets used.

Keep the error if the result is unused. rdar://9552694.

llvm-svn: 135209

2 files changed, 3 insertions, 1 deletions

diff --git a/clang/lib/ARCMigrate/TransRetainReleaseDealloc.cpp b/clang/lib/ARCMigrate/TransRetainReleaseDealloc.cpp
index d64250faf02..4eeb47437e3 100644
--- a/clang/lib/ARCMigrate/TransRetainReleaseDealloc.cpp
+++ b/clang/lib/ARCMigrate/TransRetainReleaseDealloc.cpp
@@ -70,7 +70,8 @@ public:
       if (E->getReceiverKind() == ObjCMessageExpr::Instance)
         if (Expr *rec = E->getInstanceReceiver()) {
           rec = rec->IgnoreParenImpCasts();
-          if (rec->getType().getObjCLifetime() == Qualifiers::OCL_ExplicitNone){
+          if (rec->getType().getObjCLifetime() == Qualifiers::OCL_ExplicitNone &&
+              (E->getMethodFamily() != OMF_retain || isRemovable(E))) {
             std::string err = "it is not safe to remove '";
             err += E->getSelector().getAsString() + "' message on "
                 "an __unsafe_unretained type";
diff --git a/clang/test/ARCMT/checking.m b/clang/test/ARCMT/checking.m
index 4dea3b71dff..7ab54ceb05d 100644
--- a/clang/test/ARCMT/checking.m
+++ b/clang/test/ARCMT/checking.m
@@ -39,6 +39,7 @@ struct UnsafeS {
 void test1(A *a, BOOL b, struct UnsafeS *unsafeS) {
   [unsafeS->unsafeObj retain]; // expected-error {{it is not safe to remove 'retain' message on an __unsafe_unretained type}} \
                                // expected-error {{ARC forbids explicit message send}}
+  id foo = [unsafeS->unsafeObj retain]; // no warning.
   [a dealloc];
   [a retain];
   [a retainCount]; // expected-error {{ARC forbids explicit message send of 'retainCount'}}