do not use valDecl if it is null

[sagi]

Summary

from the backtrace :

clang::TagType::getDecl (this=0x0)

so I think it is better to check that it is not null before using it.

[jbcoe]

I'm not qualified to review this fix but i think it would be more compelling if accompanied by a test that fails without the fix.

[sagi]

I will add to this review request the test that you added in D37639

[jbcoe]

The test I wrote for D37639 is not great (nor is the code fixed I proposed). A Python-free test would be much better. Lots of the build bots (to the best of my knowledge) don't run Python tests.

lib/AST/ItaniumMangle.cpp

     }
 
     if (const VarDecl *VD = dyn_cast<VarDecl>(ND)) {
+
+      QualType valDecl = VD->getType();
+      if (valDecl.isNull())
+          break;
+
+      const RecordType* RT = VD->getType()->getAs<RecordType>();
+      if (!RT) break;
+
       // We must have an anonymous union or struct declaration.
-      const RecordDecl *RD =
-        cast<RecordDecl>(VD->getType()->getAs<RecordType>()->getDecl());
+      const RecordDecl *RD = cast<RecordDecl>(RT->getDecl());
 
       // Itanium C++ ABI 5.1.2:
       //