Tweak the ObjCAtSyncChecker to assume that a mutex is non-nil after checking that it is

nil.  Otherwise we can get false paths where a second @synchronized using the mutex
can have a bogus warning.  Fixes <rdar://problem/8578650>.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@117016 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 5 insertions, 3 deletions

diff --git a/lib/Checker/ObjCAtSyncChecker.cpp b/lib/Checker/ObjCAtSyncChecker.cpp
index dc2e664e05..41580955a9 100644
--- a/lib/Checker/ObjCAtSyncChecker.cpp
+++ b/lib/Checker/ObjCAtSyncChecker.cpp
@@ -75,13 +75,15 @@ void ObjCAtSyncChecker::PreVisitObjCAtSynchronizedStmt(CheckerContext &C,
                                   Ex);
 
         C.EmitReport(report);
+        return;
       }
     }
-    // From this point forward, we know that the mutex is null.
-    C.addTransition(nullState);
+    // Don't add a transition for 'nullState'.  If the value is
+    // under-constrained to be null or non-null, assume it is non-null
+    // afterwards.
   }
 
   if (notNullState)
     C.addTransition(notNullState);
 }
- 
+