[patch] Fix pr22849

[John McCall]

> On Mar 9, 2015, at 3:05 PM, Rafael Espíndola <rafael.espindola at gmail.com> wrote:
> If I remember correctly, clang's strategy for handling language linkage in C is to pretend that C has language linkage and say that everything has C language linkage.
> 
> If that is the case, the attached patch is probably the correct fix.

Hmm.  This is probably a crash/miscompile waiting to happen in a lot of different places.  You can produce it in potentially-evaluated code in C++, too, in an in-class initializer.

We should probably push a local DeclContext when we enter a statement-expression outside of a local context.

John.