Fix compilation failure when using libstdc++10 (#1929)

The issue is caused by deleted `std::__detail::begin` declared in `bits/iterator_concepts.h`. This would be found by ADL, and because it is deleted, compilation would fail. This change makes it so that we SFINAE on `begin(std::declval<T>())` and `end(std::declval<T>())` being well-formed.
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Natsu 2020-05-15 17:30:12 +08:00 committed by Martin Hořeňovský
parent c24f7e5b34
commit 8b5f6e26d3
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@ -446,20 +446,27 @@ namespace Catch {
#endif // CATCH_CONFIG_ENABLE_VARIANT_STRINGMAKER
namespace Catch {
struct not_this_one {}; // Tag type for detecting which begin/ end are being selected
// Import begin/ end from std here so they are considered alongside the fallback (...) overloads in this namespace
// Import begin/ end from std here
using std::begin;
using std::end;
not_this_one begin( ... );
not_this_one end( ... );
namespace detail {
template <typename...>
struct void_type {
using type = void;
};
template <typename T, typename = void>
struct is_range_impl : std::false_type {
};
template <typename T>
struct is_range {
static const bool value =
!std::is_same<decltype(begin(std::declval<T>())), not_this_one>::value &&
!std::is_same<decltype(end(std::declval<T>())), not_this_one>::value;
struct is_range_impl<T, typename void_type<decltype(begin(std::declval<T>()))>::type> : std::true_type {
};
} // namespace detail
template <typename T>
struct is_range : detail::is_range_impl<T> {
};
#if defined(_MANAGED) // Managed types are never ranges