https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120917
--- Comment #24 from Frank Heckenbach <f.heckenb...@fh-soft.de> ---
(In reply to Jason Merrill from comment #23)
>
> Then yes, it does look like it should work; libstdc++ uses that 'requires
> function call' pattern in
>
> template<typename _Tp>
> concept __is_derived_from_optional = requires (const _Tp& __t) {
> []<typename _Up>(const optional<_Up>&){ }(__t);
> };
Thanks, the lambda makes it a bit shorter, and the knowledge that libstdc++
uses it gives me more confidence. So I'll try this:
template <typename T, template <typename ...> typename P> concept
DerivedFromTemplate = requires (T v) { [] <typename ... U> (const P <U ...> &)
{ } (v); };
When experimenting, I noticed that even g++-15 still accepts this:
template <typename T> concept True = true;
template <typename T> struct S;
auto f (S <True auto>);
I don't supposed it's meant to be accepted, is it? (If it is, I could just slam
"True" in front of all of my <auto>s.) Should I file another bug report?
