[Bug c++/42336] [4.5 Regression] ICE with pointer-to-member-function argument in template function

["jamborm at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #11 from jamborm at gcc dot gnu dot org  2010-01-07 18:16 -------
The ICE happens within count_non_default_template_args which (as far
as I understand it) somehow re-creates each template parameter to see
whether it is the default one (and increments a counter if it is).  I
am not exactly sure what the option 1b means but we get an ICE even
when the template does not have default parameters:

struct X {
  void func() {}
  void f2() {}
};

template<typename T, void (X::*P)() = &T::func>
void b(T) {}

int main() {
  b<X, &X::f2>(X()); /* line 9 */
  X().func();

  return 0;
}

I also do not quite understand what the option 2 means.  If we remove
the this pointer, the method is no longer a method and thus is
sensibly turned into a function.  Gcc does this IPA-CP since 4.4 and
in IPA-SRA in trunk, primarily because of some ICEs that happen if we
don't (Honza would know more but I would suspect they were also
related to debug info).

(1a sounds nice.  However, since my knowledge and experience with debug
info (not to mention C++) code is rather limited, I would like to
discuss what needs to be done in much more detail before attempting it
myself.  But it certainly looks interesting.)


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42336