932fbc868a
This adds the missing std::from_chars overloads for floating-point types, as required for C++17 conformance. The implementation is a hack and not intended to be used in the long term. Rather than parsing the string directly, this determines the initial portion of the string that matches the pattern determined by the chars_format parameter, then creates a NTBS to be parsed by strtod (or strtold or strtof). Because creating a NTBS requires allocating memory, but std::from_chars is noexcept, we need to be careful to minimise allocation. Even after being careful, allocation failure is still possible, and so a non-conforming std::no_more_memory error code might be returned. Because strtod et al depend on the current locale, but std::from_chars does not, we change the current thread's locale to "C" using newlocale and uselocale before calling strtod, and restore it afterwards. Because strtod doesn't have the equivalent of a std::chars_format parameter, it has to examine the input to determine the format in use, even though the std::from_chars code has already parsed it once (or twice for large input strings!) By replacing the use of strtod we could avoid allocation, avoid changing locale, and use optimised code paths specific to each std::chars_format case. We would also get more portable behaviour, rather than depending on the presence of uselocale, and on any bugs or quirks of the target libc's strtod. Replacing strtod is a project for a later date. libstdc++-v3/ChangeLog: * acinclude.m4 (libtool_VERSION): Bump version. * config.h.in: Regenerate. * config/abi/pre/gnu.ver: Add GLIBCXX_3.4.29 version and new exports. * config/os/gnu-linux/ldbl-extra.ver: Add _GLIBCXX_LDBL_3.4.29 version and new export. * configure: Regenerate. * configure.ac: Check for <xlocale.h> and uselocale. * crossconfig.m4: Add macro or checks for uselocale. * include/std/charconv (from_chars): Declare overloads for float, double, and long double. * src/c++17/Makefile.am: Add new file. * src/c++17/Makefile.in: Regenerate. * src/c++17/floating_from_chars.cc: New file. (from_chars): Define for float, double, and long double. * testsuite/20_util/from_chars/1_c++20_neg.cc: Prune extra diagnostics caused by new overloads. * testsuite/20_util/from_chars/1_neg.cc: Likewise. * testsuite/20_util/from_chars/2.cc: Check leading '+'. * testsuite/20_util/from_chars/4.cc: New test. * testsuite/20_util/from_chars/5.cc: New test. * testsuite/util/testsuite_abi.cc: Add new symbol versions. |
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| config | ||
| doc | ||
| include | ||
| libsupc++ | ||
| po | ||
| python | ||
| scripts | ||
| src | ||
| testsuite | ||
| acinclude.m4 | ||
| aclocal.m4 | ||
| ChangeLog | ||
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| ChangeLog-2016 | ||
| ChangeLog-2017 | ||
| ChangeLog-2018 | ||
| ChangeLog-2019 | ||
| config.h.in | ||
| configure | ||
| configure.ac | ||
| configure.host | ||
| crossconfig.m4 | ||
| fragment.am | ||
| linkage.m4 | ||
| Makefile.am | ||
| Makefile.in | ||
| README | ||
file: libstdc++-v3/README New users may wish to point their web browsers to the file index.html in the 'doc/html' subdirectory. It contains brief building instructions and notes on how to configure the library in interesting ways.