https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99117
--- Comment #16 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
So perhaps (totally untested):
--- libstdc++-v3/include/std/valarray.jj 2021-01-04 10:26:02.366967342
+0100
+++ libstdc++-v3/include/std/valarray 2021-02-23 15:16:22.402688841 +0100
@@ -838,7 +838,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 630. arrays of valarray.
if (_M_size == __e.size())
- std::__valarray_copy(__e, _M_size, _Array<_Tp>(_M_data));
+ std::__valarray_copy(__e, _M_size, _M_data);
else
{
if (_M_data)
--- libstdc++-v3/include/bits/valarray_array.tcc.jj 2021-01-04
10:26:03.768951467 +0100
+++ libstdc++-v3/include/bits/valarray_array.tcc 2021-02-23
15:15:29.273282041 +0100
@@ -146,6 +146,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
*__p = __e[__i];
}
+ // Copy n consecutive elements of e into consecutive elements of p.
+ // I.e. p[i] = e[i]. p can alias what e uses.
+ template<typename _Tp, class _Dom>
+ void
+ __valarray_copy(const _Expr<_Dom, _Tp>& __e, size_t __n, _Tp* __p)
+ {
+ for (size_t __i = 0; __i < __n; ++__i, ++__p)
+ *__p = __e[__i];
+ }
+
// Copy n consecutive elements of e into elements of a using stride
// s. I.e., a[0] = e[0], a[s] = e[1], a[2*s] = e[2].
template<typename _Tp, class _Dom>
