[Bug c++/118698] [14/15 Regression] Compiler ICE on concept code accepted by MSVC and clang

[ppalka at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118698

--- Comment #13 from Patrick Palka <ppalka at gcc dot gnu.org> ---
If we strengthen the comment #6 testcase with

@@ -6,4 +6,4 @@ concept tt = tttt<Fn, T>;
 template <typename T, template <typename> typename U>
 concept is_specialization_of = tt<decltype([]{ }),T>;
 template <typename T> concept is_foo = is_specialization_of<T,foo>;
-auto ttt =  is_foo<foo<int>> ;
+static_assert(!is_foo<foo<int>>);

then GCC >= 14 ICEs, and GCC < 14 incorrectly reject, exhibiting no real
regression.