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From: Jonathan Wakely <redi@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org, libstdc++-cvs@gcc.gnu.org Subject: [gcc r12-7676] libstdc++: Ensure that std::from_chars is declared when supported Date: Wed, 16 Mar 2022 16:16:01 +0000 (GMT) [thread overview] Message-ID: <20220316161601.1CDD63840C31@sourceware.org> (raw) https://gcc.gnu.org/g:5a4e208022e7047af3a15a3dedb715ad801db160 commit r12-7676-g5a4e208022e7047af3a15a3dedb715ad801db160 Author: Jonathan Wakely <jwakely@redhat.com> Date: Fri Mar 11 14:36:18 2022 +0000 libstdc++: Ensure that std::from_chars is declared when supported This adjusts the declarations in <charconv> to match when the definition is present. This solves the issue that std::from_chars is present on Solaris 11.3 (using fast_float) but was not declared in the header (because the declarations were guarded by _GLIBCXX_HAVE_USELOCALE). Additionally, do not define __cpp_lib_to_chars unless both from_chars and to_chars are supported (which is only true for IEEE float and double). We might still provide from_chars (via strtold) but if to_chars isn't provided, we shouldn't define the feature test macro. Finally, this simplifies some of the preprocessor checks in the bodies of std::from_chars in src/c++17/floating_from_chars.cc and hoists the repeated code for the strtod version into a new function template. N.B. the long double overload of std::from_chars will always be defined if the float and double overloads are defined. We can always use one of strtold or fast_float's binary64 routines (although the latter might produce errors for some long double values if they are not representable as binary64). libstdc++-v3/ChangeLog: * include/std/charconv (__cpp_lib_to_chars): Only define when both from_chars and to_chars are supported for floating-point types. (from_chars, to_chars): Adjust preprocessor conditions guarding declarations. * include/std/version (__cpp_lib_to_chars): Adjust condition to match <charconv> definition. * src/c++17/floating_from_chars.cc (from_chars_strtod): New function template. (from_chars): Simplify preprocessor checks and use from_chars_strtod when appropriate. Diff: --- libstdc++-v3/include/std/charconv | 8 +- libstdc++-v3/include/std/version | 3 +- libstdc++-v3/src/c++17/floating_from_chars.cc | 120 +++++++++----------------- 3 files changed, 45 insertions(+), 86 deletions(-) diff --git a/libstdc++-v3/include/std/charconv b/libstdc++-v3/include/std/charconv index a3f8c7718b2..2ce9c7d4cb9 100644 --- a/libstdc++-v3/include/std/charconv +++ b/libstdc++-v3/include/std/charconv @@ -43,7 +43,8 @@ #include <bits/error_constants.h> // for std::errc #include <ext/numeric_traits.h> -#if _GLIBCXX_HAVE_USELOCALE +#if _GLIBCXX_FLOAT_IS_IEEE_BINARY32 && _GLIBCXX_DOUBLE_IS_IEEE_BINARY64 \ + && __SIZE_WIDTH__ >= 32 # define __cpp_lib_to_chars 201611L #endif @@ -686,7 +687,7 @@ namespace __detail operator^=(chars_format& __lhs, chars_format __rhs) noexcept { return __lhs = __lhs ^ __rhs; } -#if _GLIBCXX_HAVE_USELOCALE +#if defined __cpp_lib_to_chars || _GLIBCXX_HAVE_USELOCALE from_chars_result from_chars(const char* __first, const char* __last, float& __value, chars_format __fmt = chars_format::general) noexcept; @@ -700,8 +701,7 @@ namespace __detail chars_format __fmt = chars_format::general) noexcept; #endif -#if _GLIBCXX_FLOAT_IS_IEEE_BINARY32 && _GLIBCXX_DOUBLE_IS_IEEE_BINARY64 \ - && __SIZE_WIDTH__ >= 32 +#if defined __cpp_lib_to_chars // Floating-point std::to_chars // Overloads for float. diff --git a/libstdc++-v3/include/std/version b/libstdc++-v3/include/std/version index 461e65b5fab..d730a7ea3c7 100644 --- a/libstdc++-v3/include/std/version +++ b/libstdc++-v3/include/std/version @@ -171,7 +171,8 @@ #endif #define __cpp_lib_shared_ptr_weak_type 201606L #define __cpp_lib_string_view 201803L -#if _GLIBCXX_HAVE_USELOCALE +#if _GLIBCXX_FLOAT_IS_IEEE_BINARY32 && _GLIBCXX_DOUBLE_IS_IEEE_BINARY64 \ + && __SIZE_WIDTH__ >= 32 # define __cpp_lib_to_chars 201611L #endif #define __cpp_lib_unordered_map_try_emplace 201411L diff --git a/libstdc++-v3/src/c++17/floating_from_chars.cc b/libstdc++-v3/src/c++17/floating_from_chars.cc index ba0426b3344..4aa2483bc28 100644 --- a/libstdc++-v3/src/c++17/floating_from_chars.cc +++ b/libstdc++-v3/src/c++17/floating_from_chars.cc @@ -65,6 +65,7 @@ extern "C" __ieee128 __strtoieee128(const char*, char**); && __SIZE_WIDTH__ >= 32 # define USE_LIB_FAST_FLOAT 1 # if __LDBL_MANT_DIG__ == __DBL_MANT_DIG__ +// No need to use strtold. # undef USE_STRTOD_FOR_FROM_CHARS # endif #endif @@ -420,6 +421,33 @@ namespace return true; } #endif + + template<typename T> + from_chars_result + from_chars_strtod(const char* first, const char* last, T& value, + chars_format fmt) noexcept + { + errc ec = errc::invalid_argument; +#if _GLIBCXX_USE_CXX11_ABI + buffer_resource mr; + pmr::string buf(&mr); +#else + string buf; + if (!reserve_string(buf)) + return make_result(first, 0, {}, ec); +#endif + size_t len = 0; + __try + { + if (const char* pat = pattern(first, last, fmt, buf)) [[likely]] + len = from_chars_impl(pat, value, ec); + } + __catch (const std::bad_alloc&) + { + fmt = chars_format{}; + } + return make_result(first, len, fmt, ec); + } #endif // USE_STRTOD_FOR_FROM_CHARS #if _GLIBCXX_FLOAT_IS_IEEE_BINARY32 && _GLIBCXX_DOUBLE_IS_IEEE_BINARY64 @@ -793,35 +821,15 @@ from_chars_result from_chars(const char* first, const char* last, float& value, chars_format fmt) noexcept { -#if _GLIBCXX_FLOAT_IS_IEEE_BINARY32 && _GLIBCXX_DOUBLE_IS_IEEE_BINARY64 +#if USE_LIB_FAST_FLOAT if (fmt == chars_format::hex) return __floating_from_chars_hex(first, last, value); else { - static_assert(USE_LIB_FAST_FLOAT); return fast_float::from_chars(first, last, value, fmt); } #else - errc ec = errc::invalid_argument; -#if _GLIBCXX_USE_CXX11_ABI - buffer_resource mr; - pmr::string buf(&mr); -#else - string buf; - if (!reserve_string(buf)) - return make_result(first, 0, {}, ec); -#endif - size_t len = 0; - __try - { - if (const char* pat = pattern(first, last, fmt, buf)) [[likely]] - len = from_chars_impl(pat, value, ec); - } - __catch (const std::bad_alloc&) - { - fmt = chars_format{}; - } - return make_result(first, len, fmt, ec); + return from_chars_strtod(first, last, value, fmt); #endif } @@ -829,35 +837,15 @@ from_chars_result from_chars(const char* first, const char* last, double& value, chars_format fmt) noexcept { -#if _GLIBCXX_FLOAT_IS_IEEE_BINARY32 && _GLIBCXX_DOUBLE_IS_IEEE_BINARY64 +#if USE_LIB_FAST_FLOAT if (fmt == chars_format::hex) return __floating_from_chars_hex(first, last, value); else { - static_assert(USE_LIB_FAST_FLOAT); return fast_float::from_chars(first, last, value, fmt); } #else - errc ec = errc::invalid_argument; -#if _GLIBCXX_USE_CXX11_ABI - buffer_resource mr; - pmr::string buf(&mr); -#else - string buf; - if (!reserve_string(buf)) - return make_result(first, 0, {}, ec); -#endif - size_t len = 0; - __try - { - if (const char* pat = pattern(first, last, fmt, buf)) [[likely]] - len = from_chars_impl(pat, value, ec); - } - __catch (const std::bad_alloc&) - { - fmt = chars_format{}; - } - return make_result(first, len, fmt, ec); + return from_chars_strtod(first, last, value, fmt); #endif } @@ -865,41 +853,23 @@ from_chars_result from_chars(const char* first, const char* last, long double& value, chars_format fmt) noexcept { -#if _GLIBCXX_FLOAT_IS_IEEE_BINARY32 && _GLIBCXX_DOUBLE_IS_IEEE_BINARY64 \ - && ! USE_STRTOD_FOR_FROM_CHARS +#if ! USE_STRTOD_FOR_FROM_CHARS + // Either long double is the same as double, or we can't use strtold. + // In the latter case, this might give an incorrect result (e.g. values + // out of range of double give an error, even if they fit in long double). double dbl_value; from_chars_result result; if (fmt == chars_format::hex) result = __floating_from_chars_hex(first, last, dbl_value); else { - static_assert(USE_LIB_FAST_FLOAT); result = fast_float::from_chars(first, last, dbl_value, fmt); } if (result.ec == errc{}) value = dbl_value; return result; #else - errc ec = errc::invalid_argument; -#if _GLIBCXX_USE_CXX11_ABI - buffer_resource mr; - pmr::string buf(&mr); -#else - string buf; - if (!reserve_string(buf)) - return make_result(first, 0, {}, ec); -#endif - size_t len = 0; - __try - { - if (const char* pat = pattern(first, last, fmt, buf)) [[likely]] - len = from_chars_impl(pat, value, ec); - } - __catch (const std::bad_alloc&) - { - fmt = chars_format{}; - } - return make_result(first, len, fmt, ec); + return from_chars_strtod(first, last, value, fmt); #endif } @@ -918,20 +888,8 @@ from_chars_result from_chars(const char* first, const char* last, __ieee128& value, chars_format fmt) noexcept { - buffer_resource mr; - pmr::string buf(&mr); - size_t len = 0; - errc ec = errc::invalid_argument; - __try - { - if (const char* pat = pattern(first, last, fmt, buf)) [[likely]] - len = from_chars_impl(pat, value, ec); - } - __catch (const std::bad_alloc&) - { - fmt = chars_format{}; - } - return make_result(first, len, fmt, ec); + // fast_float doesn't support IEEE binary128 format, but we can use strtold. + return from_chars_strtod(first, last, value, fmt); } #endif
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