[analyzer] Enhance the error message.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@165993 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/StaticAnalyzer/Checkers/IvarInvalidationChecker.cpp b/lib/StaticAnalyzer/Checkers/IvarInvalidationChecker.cpp
index a88b636..462066a 100644
--- a/lib/StaticAnalyzer/Checkers/IvarInvalidationChecker.cpp
+++ b/lib/StaticAnalyzer/Checkers/IvarInvalidationChecker.cpp
@@ -389,7 +389,7 @@
         os << "Property "<< PD->getName() << " needs to be invalidated";
       } else {
         os << "Instance variable "<< IvarDecl->getName()
-             << " needs to be invalidated";
+             << " needs to be invalidated or set to nil";
       }
 
       BR.EmitBasicReport(D,