On Mon, 1 Nov 2021 at 13:27, Jonathan Wakely via Libstdc++ <
libstd...@gcc.gnu.org> wrote:
> Tested powerpc64le-linux, pushed to trunk.
>
>
> The std::begin and std::end overloads for std::valarray are defined in
> terms of std::addressof(v[0]) which is undefined for an empty valarray.
>
> libstdc++-v3/ChangeLog:
>
> PR libstdc++/103022
> * include/std/valarray (begin, end): Do not dereference an empty
> valarray. Add noexcept and [[nodiscard]].
> * testsuite/26_numerics/valarray/range_access.cc: Check empty
> valarray. Check iterator properties. Run as well as compiling.
> * testsuite/26_numerics/valarray/range_access2.cc: Likewise.
> * testsuite/26_numerics/valarray/103022.cc: New test.
> ---
> libstdc++-v3/include/std/valarray | 30 +++++++++---
> .../testsuite/26_numerics/valarray/103022.cc | 15 ++++++
> .../26_numerics/valarray/range_access.cc | 49 ++++++++++++++++---
> .../26_numerics/valarray/range_access2.cc | 22 ++++++++-
> 4 files changed, 100 insertions(+), 16 deletions(-)
> create mode 100644 libstdc++-v3/testsuite/26_numerics/valarray/103022.cc
>
> diff --git a/libstdc++-v3/include/std/valarray
> b/libstdc++-v3/include/std/valarray
> index 5adc94282ee..c6242eb4db9 100644
> --- a/libstdc++-v3/include/std/valarray
> +++ b/libstdc++-v3/include/std/valarray
> @@ -1210,9 +1210,10 @@ _DEFINE_BINARY_OPERATOR(>=, __greater_equal)
> * @param __va valarray.
> */
> template<class _Tp>
> + [[__nodiscard__]]
> inline _Tp*
> - begin(valarray<_Tp>& __va)
> - { return std::__addressof(__va[0]); }
> + begin(valarray<_Tp>& __va) noexcept
> + { return __va.size() ? std::__addressof(__va[0]) : nullptr; }
>
>
I forgot to also add noexcept to the declarations in <bits/range_access.h>.
Fixed by the attached patch, committed to trunk.
commit 2b2d97fc545635a0f6aa9c9ee3b017394bc494bf
Author: Jonathan Wakely <jwak...@redhat.com>
Date: Fri Nov 5 21:42:20 2021
libstdc++: Fix inconsistent noexcept-specific for valarray begin/end
These declarations should be noexcept after I added it to the
definitions in <valarray>.
libstdc++-v3/ChangeLog:
* include/bits/range_access.h (begin(valarray), end(valarray)):
Add noexcept.
diff --git a/libstdc++-v3/include/bits/range_access.h
b/libstdc++-v3/include/bits/range_access.h
index 3dec687dd94..5e4c4727ebf 100644
--- a/libstdc++-v3/include/bits/range_access.h
+++ b/libstdc++-v3/include/bits/range_access.h
@@ -110,10 +110,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Tp> class valarray;
// These overloads must be declared for cbegin and cend to use them.
- template<typename _Tp> _Tp* begin(valarray<_Tp>&);
- template<typename _Tp> const _Tp* begin(const valarray<_Tp>&);
- template<typename _Tp> _Tp* end(valarray<_Tp>&);
- template<typename _Tp> const _Tp* end(const valarray<_Tp>&);
+ template<typename _Tp> _Tp* begin(valarray<_Tp>&) noexcept;
+ template<typename _Tp> const _Tp* begin(const valarray<_Tp>&) noexcept;
+ template<typename _Tp> _Tp* end(valarray<_Tp>&) noexcept;
+ template<typename _Tp> const _Tp* end(const valarray<_Tp>&) noexcept;
/**
* @brief Return an iterator pointing to the first element of
