https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89011
--- Comment #1 from Andreas Hangauer <ahangauer at gmx dot net> ---
I just found out that using nullptr it *does* work. So it is the initialization
by integer zero that does not work.
#include <cstddef>
template <class X, bool (X::*fcn)(int param)=0 >
struct test {
int v;
};
struct dummy {
bool fcn(int);
};
using TT = test<dummy, &dummy::fcn>; // works
using TT2 = test<dummy, nullptr>; // works
using TT3 = test<dummy, 0>; // generates ICE
using TT4 = test<dummy>; // generates ICE
