https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102284
--- Comment #6 from Johel Ernesto Guerrero Peña <johelegp at gmail dot com> --- Another example. Simplified: https://godbolt.org/z/z781c56PM. ```C++ struct ratio { int numerator; }; template<auto> struct constant; template<auto F> concept constant_invocable = requires { typename constant<(F(), 0)>; }; static_assert(not constant_invocable<[] { ratio r; (void)int{r.*&ratio::numerator}; }>); ``` ``` <source>:9:15: error: static assertion failed 9 | static_assert(not constant_invocable<[] { | ^~~~~~~~~~~~~~~~~~~~~~~~~~~ 10 | ratio r; | ~~~~~~~~ 11 | (void)int{r.*&ratio::numerator}; | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 12 | }>); | ~~ Compiler returned: 1 ``` Found while opening https://github.com/llvm/llvm-project/issues/57958: https://godbolt.org/z/KWfvEnaae. ```C++ #include <concepts> #include <cstdint> #include <functional> #include <type_traits> struct ratio { std::intmax_t numerator; std::intmax_t denominator{1}; }; template<auto F> concept constant_invocable = requires { typename std::integral_constant<int, (F(), 0)>; }; template<auto P> requires std::is_member_object_pointer_v<decltype(P)> inline constexpr bool default_initialization_leaves_uninitialized = []<class T, class M>(M T::*) { return not constant_invocable<[]() { T v; (void)M{v.*P}; }>; }(P); static_assert(default_initialization_leaves_uninitialized<&ratio::numerator>); static_assert(not default_initialization_leaves_uninitialized<&ratio::denominator>); ``` ``` <source>:22:15: error: static assertion failed 22 | static_assert(default_initialization_leaves_uninitialized<&ratio::numerator>); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Compiler returned: 1 ```
