On Fri, Apr 26, 2019 at 03:05:36PM +0100, Jonathan Wakely wrote:
> Jakub noted in https://gcc.gnu.org/ml/libstdc++/2019-04/msg00140.html
> that an unwanted std::wstring::_M_replace_dispatch symbol has started to
> be exported from the Fedora shared library. This symbol is triggered by
> the instantiation of std::wstring::assign(const char*, const char*) from
> std::__str_codecvt_in which is called from path::_S_convert_loc. The
> branch that triggers that instantiation can't actually happen in that
> case, because codecvt facets will only return noconv when the input and
> output types are the same. Guarding the assign call with an if-constexpr
> check that the types are the same avoids instantiating template
> specializations that will never actually be needed.
>
> * config/abi/pre/gnu.ver (GLIBCXX_3.4): Replace wildcard that
> matches
> wstring::_M_replace_dispatch with more specific patterns.
Can you please commit this part to 9.1 now as well (so that we don't export
it from 9.1.0 by accident)?
The rest is fine for 9.2 if you want or just on the trunk, whatever you
think is better.
> * include/bits/fs_path.h (path::_S_convert_loc<_InputIterator>):
> Create const std::string to avoid redundant call to _S_convert_loc
> with non-const pointers.
> * include/bits/locale_conv.h (__do_str_codecvt): Use if-constexpr
> to
> avoid unnecessary basic_string::assign instantiations.
Jakub
