[objcmt] Warn when modern objc migrator does not convert a NSNumber message because it requires a cast.

rdar://11525138

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@157395 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/ARCMigrate/ObjCMT.cpp b/lib/ARCMigrate/ObjCMT.cpp
index e635274..5107db8 100644
--- a/lib/ARCMigrate/ObjCMT.cpp
+++ b/lib/ARCMigrate/ObjCMT.cpp
@@ -209,6 +209,7 @@
 }
 
 bool MigrateSourceAction::BeginInvocation(CompilerInstance &CI) {
+  CI.getDiagnostics().setIgnoreAllWarnings(true);
   CI.getPreprocessorOpts().DetailedRecord = true;
   CI.getPreprocessorOpts().DetailedRecordConditionalDirectives = true;
   return true;