Open
Description
When a static assert over a requires expression fails, clang gives no insight as to how the requires expression was evaluated, it just shows the line literatim.
Clang does gives reasonable diagnostics when the same requires expression evaluation causes a constraint failure. I have hope that this mechanism can be leveraged for static_assert too
Testcase https://godbolt.org/z/fnoW3aMM9
#include <concepts>
int g(int);
#if 0
// This diagnostic is reasonable
template<typename T>
requires requires (T t)
{
{ g(t) } -> std::same_as<void>;
}
void f()
{}
#else
template<typename T>
void f()
{
// This diagnostic is no good
static_assert(requires (T t)
{
{ g(t) } -> std::same_as<void>;
});
}
#endif
void test()
{
f<int>();
}