The condition was checking if extents<int, ...> is convertible to index_type,
and not the reverse. We test implicit conversion from braced initializer list
(to cover multiple arguments) and is_convertible in case of single
index.
libstdc++-v3/ChangeLog:
* testsuite/23_containers/mdspan/extents/ctor_ints.cc: Updated
is_explicit, and added more test cases.
---
Fixed out issue that Tim pointed out on mattermost. I have checked
other usages, and this seem to be only place affected.
Tested *mdspan* test locally with all standard modes. OK for trunk?
.../23_containers/mdspan/extents/ctor_ints.cc | 20 +++++++++++++++----
1 file changed, 16 insertions(+), 4 deletions(-)
diff --git a/libstdc++-v3/testsuite/23_containers/mdspan/extents/ctor_ints.cc
b/libstdc++-v3/testsuite/23_containers/mdspan/extents/ctor_ints.cc
index fdbcb707bbe..eefeab0e6a0 100644
--- a/libstdc++-v3/testsuite/23_containers/mdspan/extents/ctor_ints.cc
+++ b/libstdc++-v3/testsuite/23_containers/mdspan/extents/ctor_ints.cc
@@ -24,18 +24,30 @@ static_assert(std::is_constructible_v<std::extents<unsigned
__int128, 1, 2>,
#endif
// No implicit conversion from integer-like objects.
-template<typename Extent, typename... OExtents>
- constexpr bool
+template<typename ExtentsType, typename OIndex, typename... RIndicies>
+ consteval bool
is_explicit()
{
- return std::is_nothrow_constructible_v<Extent, OExtents...>
- && !std::is_convertible_v<Extent, OExtents...>;
+ if (!std::is_nothrow_constructible_v<ExtentsType, OIndex, RIndicies...>)
+ return false;
+ if constexpr (sizeof...(RIndicies) == 0)
+ if (std::is_convertible_v<OIndex, ExtentsType>)
+ return false;
+
+ extern void testConv(ExtentsType);
+ return !requires (OIndex index, RIndicies... rindicies)
+ { testConv({index, rindicies...}); };
}
static_assert(is_explicit<std::extents<int, 1>, int>());
static_assert(is_explicit<std::extents<int, 1>, unsigned int>());
static_assert(is_explicit<std::extents<unsigned int, 1>, int>());
+static_assert(is_explicit<std::dextents<int, 1>, int>());
+static_assert(is_explicit<std::dextents<int, 2>, int, int>());
+static_assert(is_explicit<std::dextents<int, 3>, int, int, int>());
+
+
constexpr bool
test_all()
{
--
2.53.0
