Jonathan Wakely
5a4e208022
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.
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.