diff options
author | Jonathan Wakely <jwakely@redhat.com> | 2021-06-04 20:28:04 +0100 |
---|---|---|
committer | Jonathan Wakely <jwakely@redhat.com> | 2021-06-04 21:33:59 +0100 |
commit | 621ea10ca060ba19ec693aa73b5e29d553cca849 (patch) | |
tree | c6e6597462a2efb9f5c72357b4ac701e97e1bb9a /libstdc++-v3 | |
parent | 3e5f2425f80aedd00f28235022a2755eb46f310d (diff) | |
download | gcc-621ea10ca060ba19ec693aa73b5e29d553cca849.zip gcc-621ea10ca060ba19ec693aa73b5e29d553cca849.tar.gz gcc-621ea10ca060ba19ec693aa73b5e29d553cca849.tar.bz2 |
libstdc++: Implement LWG 3403 for std::ranges::ssize
I already changed the constraints for ranges::ssize to use ranges::size,
this implements the rest of LWG 3403, so that the returned type is the
signed type corresponding to the result of ranges::size.
Signed-off-by: Jonathan Wakely <jwakely@redhat.com>
libstdc++-v3/ChangeLog:
* include/bits/ranges_base.h (_SSize): Return the result of
ranges::size converted to the wider of make-signed-like-t<S> and
ptrdiff_t, rather than the ranges different type.
* testsuite/std/ranges/access/ssize.cc: Adjust expected result
for an iota_view that uses an integer class type for its
difference_type.
Diffstat (limited to 'libstdc++-v3')
-rw-r--r-- | libstdc++-v3/include/bits/ranges_base.h | 22 | ||||
-rw-r--r-- | libstdc++-v3/testsuite/std/ranges/access/ssize.cc | 9 |
2 files changed, 22 insertions, 9 deletions
diff --git a/libstdc++-v3/include/bits/ranges_base.h b/libstdc++-v3/include/bits/ranges_base.h index 61d91eb..e3c3962 100644 --- a/libstdc++-v3/include/bits/ranges_base.h +++ b/libstdc++-v3/include/bits/ranges_base.h @@ -425,22 +425,32 @@ namespace ranges struct _SSize { + // _GLIBCXX_RESOLVE_LIB_DEFECTS + // 3403. Domain of ranges::ssize(E) doesn't match ranges::size(E) template<typename _Tp> requires requires (_Tp& __t) { _Size{}(__t); } constexpr auto operator()(_Tp&& __t) const noexcept(noexcept(_Size{}(__t))) { - using __iter_type = decltype(_Begin{}(__t)); - using __diff_type = iter_difference_t<__iter_type>; - using __gnu_cxx::__int_traits; auto __size = _Size{}(__t); - if constexpr (integral<__diff_type>) + using __size_type = decltype(__size); + // Return the wider of ptrdiff_t and make-signed-like-t<__size_type>. + if constexpr (integral<__size_type>) { - if constexpr (__int_traits<__diff_type>::__digits + using __gnu_cxx::__int_traits; + if constexpr (__int_traits<__size_type>::__digits < __int_traits<ptrdiff_t>::__digits) return static_cast<ptrdiff_t>(__size); + else + return static_cast<make_signed_t<__size_type>>(__size); } - return static_cast<__diff_type>(__size); +#if defined __STRICT_ANSI__ && defined __SIZEOF_INT128__ + // For strict-ansi modes integral<__int128> is false + else if constexpr (__detail::__is_int128<__size_type>) + return static_cast<unsigned __int128>(__size); +#endif + else // Must be one of __max_diff_type or __max_size_type. + return __detail::__max_diff_type(__size); } }; diff --git a/libstdc++-v3/testsuite/std/ranges/access/ssize.cc b/libstdc++-v3/testsuite/std/ranges/access/ssize.cc index b00ec5d..f53f462 100644 --- a/libstdc++-v3/testsuite/std/ranges/access/ssize.cc +++ b/libstdc++-v3/testsuite/std/ranges/access/ssize.cc @@ -76,9 +76,12 @@ void test06() { auto i = std::views::iota(1ull, 5u); - auto s = std::ranges::ssize(i); - using R = std::ranges::range_difference_t<decltype(i)>; - static_assert( std::same_as<decltype(s), R> ); + auto s = std::ranges::size(i); + auto ss = std::ranges::ssize(i); + // std::ranges::range_difference_t<decltype(i)> is larger than long long, + // but LWG 3403 says ranges::ssize(i) returns the signed version of the + // type that ranges::size(i) returns, not the range's difference_type. + static_assert( std::same_as<decltype(ss), std::make_signed_t<decltype(s)>> ); VERIFY( s == 4 ); } |