[Bug c++/67147] [concepts] ICE on checking concept with default template arguments

[antoshkka at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67147

--- Comment #4 from Antony Polukhin <antoshkka at gmail dot com> ---
Shorter reproducer:

template<typename T, int = sizeof(T)> concept bool fn = true;
template <fn T> int test();



Above sample produces the following output:

<source>:1:28: internal compiler error: in tsubst, at cp/pt.c:14368

 template<typename T, int = sizeof(T)> concept bool fn = true;

                            ^~~~~~~~~