We are passing a value type as the first argument to is_nothrow_assignable_v,
but the result of that is always false. Since this predicate is a part of the
condition that guards the corresponding optimizations for these algorithms, this
bug means these optimizations are never used. We should be passing a reference
type to is_nothrow_assignable_v instead.
libstdc++-v3/ChangeLog:
* include/bits/ranges_uninitialized.h
(uninitialized_copy_fn::operator()): Pass a reference type as the first
argument to is_nothrow_assignable_v.
(uninitialized_copy_fn::operator()): Likewise.
(uninitialized_move_fn::operator()): Likewise. Return an in_out_result
with the input iterator stripped of its move_iterator.
(uninitialized_move_n_fn::operator()): Likewise.
(uninitialized_fill_fn::operator()): Pass a reference type as the first
argument to is_nothrow_assignable_v.
(uninitialized_fill_n_fn::operator()): Likewise.
---
.../include/bits/ranges_uninitialized.h | 24 +++++++++++--------
1 file changed, 14 insertions(+), 10 deletions(-)
diff --git a/libstdc++-v3/include/bits/ranges_uninitialized.h
b/libstdc++-v3/include/bits/ranges_uninitialized.h
index 01e1cad646c..f97a07a9b4a 100644
--- a/libstdc++-v3/include/bits/ranges_uninitialized.h
+++ b/libstdc++-v3/include/bits/ranges_uninitialized.h
@@ -269,7 +269,7 @@ namespace ranges
if constexpr (sized_sentinel_for<_ISent, _Iter>
&& sized_sentinel_for<_OSent, _Out>
&& is_trivial_v<_OutType>
- && is_nothrow_assignable_v<_OutType,
+ && is_nothrow_assignable_v<_OutType&,
iter_reference_t<_Iter>>)
{
auto __d1 = ranges::distance(__ifirst, __ilast);
@@ -316,7 +316,7 @@ namespace ranges
using _OutType = remove_reference_t<iter_reference_t<_Out>>;
if constexpr (sized_sentinel_for<_Sent, _Out>
&& is_trivial_v<_OutType>
- && is_nothrow_assignable_v<_OutType,
+ && is_nothrow_assignable_v<_OutType&,
iter_reference_t<_Iter>>)
{
auto __d = ranges::distance(__ofirst, __olast);
@@ -354,13 +354,15 @@ namespace ranges
if constexpr (sized_sentinel_for<_ISent, _Iter>
&& sized_sentinel_for<_OSent, _Out>
&& is_trivial_v<_OutType>
- && is_nothrow_assignable_v<_OutType,
+ && is_nothrow_assignable_v<_OutType&,
iter_rvalue_reference_t<_Iter>>)
{
auto __d1 = ranges::distance(__ifirst, __ilast);
auto __d2 = ranges::distance(__ofirst, __olast);
- return ranges::copy_n(std::make_move_iterator(__ifirst),
- std::min(__d1, __d2), __ofirst);
+ auto [__in, __out]
+ = ranges::copy_n(std::make_move_iterator(__ifirst),
+ std::min(__d1, __d2), __ofirst);
+ return {std::move(__in).base(), __out};
}
else
{
@@ -404,12 +406,14 @@ namespace ranges
using _OutType = remove_reference_t<iter_reference_t<_Out>>;
if constexpr (sized_sentinel_for<_Sent, _Out>
&& is_trivial_v<_OutType>
- && is_nothrow_assignable_v<_OutType,
+ && is_nothrow_assignable_v<_OutType&,
iter_rvalue_reference_t<_Iter>>)
{
auto __d = ranges::distance(__ofirst, __olast);
- return ranges::copy_n(std::make_move_iterator(__ifirst),
- std::min(__n, __d), __ofirst);
+ auto [__in, __out]
+ = ranges::copy_n(std::make_move_iterator(__ifirst),
+ std::min(__n, __d), __ofirst);
+ return {std::move(__in).base(), __out};
}
else
{
@@ -436,7 +440,7 @@ namespace ranges
{
using _ValueType = remove_reference_t<iter_reference_t<_Iter>>;
if constexpr (is_trivial_v<_ValueType>
- && is_nothrow_assignable_v<_ValueType, const _Tp&>)
+ && is_nothrow_assignable_v<_ValueType&, const _Tp&>)
return ranges::fill(__first, __last, __x);
else
{
@@ -469,7 +473,7 @@ namespace ranges
{
using _ValueType = remove_reference_t<iter_reference_t<_Iter>>;
if constexpr (is_trivial_v<_ValueType>
- && is_nothrow_assignable_v<_ValueType, const _Tp&>)
+ && is_nothrow_assignable_v<_ValueType&, const _Tp&>)
return ranges::fill_n(__first, __n, __x);
else
{
--
2.25.1.377.g2d2118b814
