[RFA/stabs reader] Fix v3 duplicate constructors problem

[Jim Blandy]

Jason Merrill <jason@redhat.com> writes:
> Constructors and destructors have traditionally had a special calling
> convention.  Though I suppose that as of v3, we've gone to clones rather
> than extra hidden parameters, so it would be more feasible to allow users
> to call them directly from the debugger.  In any case, it needs some sort
> of special handling.

Wouldn't it be reasonable for GDB to support `new' expressions?