[PATCH] Sema: Propagate the mangling number into instantiations

[Richard Smith]

  Does this do the right thing in the context of variadic template pack expansions? For lambda expressions, we deliberately do not inherit the mangling number because that would not be correct:

    template<typename ...Ts> void f(std::function<T()> ...fn = []{ return T(); }) {}

  ... would give all the instantiated lambdas the same mangling number, for instance.

  What we do for lambdas is to compute the mangling number during instantiation in the same way we compute it during parsing.

http://llvm-reviews.chandlerc.com/D2203