https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80265
Eric Gallager <egallager at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |egallager at gcc dot gnu.org
--- Comment #21 from Eric Gallager <egallager at gcc dot gnu.org> ---
(In reply to palves from comment #19)
> Author: palves
> Date: Mon Jun 12 22:22:39 2017
> New Revision: 249137
>
> URL: https://gcc.gnu.org/viewcvs?rev=249137&root=gcc&view=rev
> Log:
> Finish implementing P0426R1 "Constexpr for std::char_traits" for C++17
>
> As discussed in PR c++/80265 ("__builtin_{memcmp,memchr,strlen} are
> not usable in constexpr functions"), use __builtin_constant_p to tell
> whether we can defer to a constexpr algorithm.
>
> I used __always_inline__ just to be thorough. It isn't really really
> necessary as far as I could determine.
>
> Changes like these:
>
> if (__n == 0)
> return 0;
> - return wmemcmp(__s1, __s2, __n);
> + else
> + return wmemcmp(__s1, __s2, __n);
>
> are necessary otherwise G++ complains that we're calling a
> non-constexpr function, which looks like a a manifestation of PR67026
> to me.
>
> libstdc++-v3:
> 2017-06-12 Pedro Alves <pal...@redhat.com>
>
> * doc/xml/manual/status_cxx2017.xml: Update C++17 constexpr
> char_traits status.
> * doc/html/*: Regenerate.
>
> * include/bits/char_traits.h (_GLIBCXX_ALWAYS_INLINE): Define if
> not already defined.
> (__cpp_lib_constexpr_char_traits): Uncomment.
> (__constant_string_p, __constant_char_array_p): New.
> (std::char_traits<char>, std::char_traits<wchar_t>): Add
> _GLIBCXX17_CONSTEXPR on compare, length and find and use
> __constant_string_p, __constant_char_array_p and
> __builtin_constant_p to defer to __gnu_cxx::char_traits at compile
> time.
>
> * testsuite/21_strings/char_traits/requirements/
> constexpr_functions_c++17.cc: Uncomment
> __cpp_lib_constexpr_char_traits tests. Uncomment
> test_compare<char>, test_length<char>, test_find<char>,
> test_compare<wchar_t>, test_length<wchar_t> and test_find<wchar_t>
> static_assert tests.
>
> Modified:
> trunk/libstdc++-v3/ChangeLog
> trunk/libstdc++-v3/doc/xml/manual/status_cxx2017.xml
> trunk/libstdc++-v3/include/bits/char_traits.h
>
> trunk/libstdc++-v3/testsuite/21_strings/char_traits/requirements/
> constexpr_functions_c++17.cc
(In reply to Jonathan Wakely from comment #20)
> Author: redi
> Date: Tue Sep 12 16:27:01 2017
> New Revision: 252030
>
> URL: https://gcc.gnu.org/viewcvs?rev=252030&root=gcc&view=rev
> Log:
> Finish implementing P0426R1 "Constexpr for std::char_traits" for C++17
>
> As discussed in PR c++/80265 ("__builtin_{memcmp,memchr,strlen} are
> not usable in constexpr functions"), use __builtin_constant_p to tell
> whether we can defer to a constexpr algorithm.
>
> I used __always_inline__ just to be thorough. It isn't really really
> necessary as far as I could determine.
>
> Changes like these:
>
> if (__n == 0)
> return 0;
> - return wmemcmp(__s1, __s2, __n);
> + else
> + return wmemcmp(__s1, __s2, __n);
>
> are necessary otherwise G++ complains that we're calling a
> non-constexpr function, which looks like a a manifestation of PR67026
> to me.
>
> libstdc++-v3:
> 2017-06-12 Pedro Alves <pal...@redhat.com>
>
> * doc/xml/manual/status_cxx2017.xml: Update C++17 constexpr
> char_traits status.
> * doc/html/*: Regenerate.
>
> * include/bits/char_traits.h (_GLIBCXX_ALWAYS_INLINE): Define if
> not already defined.
> (__cpp_lib_constexpr_char_traits): Uncomment.
> (__constant_string_p, __constant_char_array_p): New.
> (std::char_traits<char>, std::char_traits<wchar_t>): Add
> _GLIBCXX17_CONSTEXPR on compare, length and find and use
> __constant_string_p, __constant_char_array_p and
> __builtin_constant_p to defer to __gnu_cxx::char_traits at compile
> time.
>
> * testsuite/21_strings/char_traits/requirements/
> constexpr_functions_c++17.cc: Uncomment
> __cpp_lib_constexpr_char_traits tests. Uncomment
> test_compare<char>, test_length<char>, test_find<char>,
> test_compare<wchar_t>, test_length<wchar_t> and test_find<wchar_t>
> static_assert tests.
>
> Modified:
> branches/gcc-7-branch/libstdc++-v3/ChangeLog
> branches/gcc-7-branch/libstdc++-v3/doc/html/manual/status.html
> branches/gcc-7-branch/libstdc++-v3/doc/xml/manual/status_cxx2017.xml
> branches/gcc-7-branch/libstdc++-v3/include/bits/char_traits.h
>
> branches/gcc-7-branch/libstdc++-v3/testsuite/21_strings/char_traits/
> requirements/constexpr_functions_c++17.cc
Did these fix it?
