https://gcc.gnu.org/g:06e627e1e246e423bf2af754f9a1401cf6ae3c99
commit r16-3402-g06e627e1e246e423bf2af754f9a1401cf6ae3c99
Author: Patrick Palka <ppa...@redhat.com>
Date: Tue Aug 26 15:45:57 2025 -0400
libstdc++/ranges: Prefer using offset-based _CachedPosition
The offset-based partial specialization of _CachedPosition for
random-access iterators is currently only selected if the offset type is
smaller than the iterator type. Before r12-1018-g46ed811bcb4b86 this
made sense since the main partial specialization only stored the
iterator (incorrectly). After that bugfix, the main partial
specialization now effectively stores a std::optional<iter> so the
size constraint is inaccurate. And this main partial specialization
must invalidate itself upon copy/move unlike the offset-based partial
specialization. So I think we should just always prefer the
offset-based _CachedPosition for a random-access iterator, even if the
offset type happens to be larger than the iterator type.
libstdc++-v3/ChangeLog:
* include/std/ranges (__detail::_CachedPosition): Remove
additional size constraint on the offset-based partial
specialization.
Reviewed-by: Tomasz Kamiński <tkami...@redhat.com>
Reviewed-by: Jonathan Wakely <jwak...@redhat.com>
Diff:
---
libstdc++-v3/include/std/ranges | 2 --
1 file changed, 2 deletions(-)
diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges
index efe62969d657..2970b2cbe00b 100644
--- a/libstdc++-v3/include/std/ranges
+++ b/libstdc++-v3/include/std/ranges
@@ -1585,8 +1585,6 @@ namespace views::__adaptor
};
template<random_access_range _Range>
- requires (sizeof(range_difference_t<_Range>)
- <= sizeof(iterator_t<_Range>))
struct _CachedPosition<_Range>
{
private:
