is_virtual_base_of uses common names for internal types (X and Y); naming conflicts result

[Karl Voelker <ktvoelker@…>]

is_virtual_base_of (and probably a lot of other type traits, I suspect) uses some structs internally, X and Y, which inherit from the types being analyzed. But if the derived type under analysis (from which Y inherits) has a method Y, the constructor Y::Y in the internal struct becomes a problem. (At least, under gcc 4.5.0 20100520 prerelease.)

I've attached a simple demonstration of the problem. I attempted to compile with: g++ -c MyDerived.cpp.

One obvious solution to this problem is to change X and Y to have bizarre names that are unlikely to conflict with user code. I have attached a patch to this effect. However, I suspect that this problem occurs in many other type traits.

I'm not enough of a C++ spec expert to say whether my program ought to compile or not. Sorry. The real-world case from which my example was distilled is known to compile on MSVC++. I do not have access to MSVC++ to test my distillation.

[Karl Voelker <ktvoelker@…>]

Patch for the problem

[Karl Voelker <ktvoelker@…>]

Example of the problem

[Karl Voelker <ktvoelker@…>]

My compiler output for the example

[John Maddock]

(In [64251]) Mangle the names of internal classes so they're less likely to conflict with derived class names and members. Fixes #4453.