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| author | Patrick Palka <ppalka@redhat.com> | 2025-02-28 10:15:45 -0500 |
|---|---|---|
| committer | Patrick Palka <ppalka@redhat.com> | 2025-02-28 10:15:45 -0500 |
| commit | 815f1f27a1dba2f0acd1f02d0beafedadebe967c (patch) | |
| tree | 9323b0d3d5f5022fcbcfbc71619ad14ab4ce936c | |
| parent | 4342c50ca84ae5448c0128c52120f4fe9005f203 (diff) | |
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libstdc++: Improve optional's <=> constraint recursion workaround [PR104606]
It turns out the reason the behavior of this testcase changed after CWG
2369 is because validity of the substituted return type is now checked
later, after constraints. So a more reliable workaround for this issue
is to add a constraint to check the validity of the return type earlier,
matching the pre-CWG 2369 semantics.
PR libstdc++/104606
libstdc++-v3/ChangeLog:
* include/std/optional (operator<=>): Revert r14-9771 change.
Add constraint checking the validity of the return type
compare_three_way_result_t before the three_way_comparable_with
constraint.
Reviewed-by: Jonathan Wakely <jwakely@redhat.com>
| -rw-r--r-- | libstdc++-v3/include/std/optional | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/libstdc++-v3/include/std/optional b/libstdc++-v3/include/std/optional index 832dc6f..a616dc0 100644 --- a/libstdc++-v3/include/std/optional +++ b/libstdc++-v3/include/std/optional @@ -1685,7 +1685,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION template<typename _Tp, typename _Up> requires (!__is_derived_from_optional<_Up>) - && three_way_comparable_with<_Up, _Tp> + && requires { typename compare_three_way_result_t<_Tp, _Up>; } + && three_way_comparable_with<_Tp, _Up> constexpr compare_three_way_result_t<_Tp, _Up> operator<=> [[nodiscard]] (const optional<_Tp>& __x, const _Up& __v) { return bool(__x) ? *__x <=> __v : strong_ordering::less; } |