[cfe-commits] RecursiveASTVisitor: visit all implicit template specializations with the primary template

[Richard Smith]

Hi,

Our current strategy is that RecursiveASTVisitor attempts to visit template
specializations as part of visiting the template from which the
specializations are instantiated. This goes wrong for a partial
specialization of a member template of a class template:

  template<typename T> struct A {
    template<typename U> struct B;
  };

  template<typename T> template<typename U> struct A<T>::B<U*> {};

Here, it's not trivial to find the specializations which are instantiated
from the partial specialization, and the RecursiveASTVisitor fails to find
them.

A somewhat-related problem is that we do not visit template specializations
where we have instantiated the declaration but not the definition. In such
cases, we do not know (and, from the RecursiveASTVisitor, cannot reasonably
compute) which primary template or partial specialization an instantiated
declaration should be associated with, so the existing strategy cannot be
applied there.

I propose that we fix both of these issues by visiting all implicit
instantiations of a template (including cases where we have not
instantiated a definition) when we visit the primary template; a patch
implementing this is attached.

This conflicts with the chosen direction from when this functionality was
added [1], so I'd like to hear any concerns with this direction.

Thanks!
Richard

[1]
http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20100830/033977.html
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