Currently, this ill-formed program which violates [range.utility.conv.to]/1 and [range.utility.conv.adaptors]/1 isn't rejected when using libc++ (Godbolt link):
#include <concepts>
#include <ranges>
int main() {
struct R {
int* begin() const;
int* end() const;
operator int() const { return 0; }
};
std::same_as<int> auto m [[maybe_unused]] = std::ranges::to<int>(R{});
std::same_as<int> auto n [[maybe_unused]] = R{} | std::ranges::to<int>();
}
It's weird that the "class" part is mentioned in comments but not actually implemented.
// Mandates: C is a cv-unqualified class type. static_assert(!is_const_v<_Container>, "The target container cannot be const-qualified, please remove the const"); static_assert( !is_volatile_v<_Container>, "The target container cannot be volatile-qualified, please remove the volatile"); // Mandates: C is a cv-unqualified class type. static_assert(!is_const_v<_Container>, "The target container cannot be const-qualified, please remove the const"); static_assert( !is_volatile_v<_Container>, "The target container cannot be volatile-qualified, please remove the volatile");Note that libstdc++ and MSVC STL also reject union types by only using is_class_v, despite that the term "class type" in the C++ core language specification also covers union types. Perhaps we should also only accept non-union class types here and submit an LWG issue for this.
Edit: LWG4229
RetroSearch is an open source project built by @garambo | Open a GitHub Issue
Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo
HTML:
3.2
| Encoding:
UTF-8
| Version:
0.7.4