It was using libsyntax last I checked, so adding to that would be beneficial, for the long term.

I don't think perfection is a big deal in this scenario, at this moment as we don't have `#[compile_fail]` yet, and we're talking about a subset of the compiler tests. 

But, fair enough, I can understand the confusion it might add, I'm happy enough to drop it.

So, the question becomes, is the changing to regex still wanted? 

Regarding dependency on regex_macros, compiletest does seem to get compiled at stage0, but no tests are run at that stage. Adding regex_macros as a dependency on compiletest seems fine for compile but gets a runtime error in expansion when tests are run. I hope to be able to look into that soon.