Re: tm vs. std:.tm type in symbol name of std::time_put<>::put()

[Marc Glisse <marc dot glisse at inria dot fr>]

On Fri, 15 Sep 2017, Johan Alfredsson wrote:

> I ran into a symbol name difference linking an executable compiled with
> clang 5.0 vs. compiling with gcc 7.1.0 on Solaris/SPARC.
>
> In bits/locale_facets_nonio.tcc, there is the following template:
>
> template<typename _CharT, typename _OutIter>
> _OutIter
> time_put<_CharT, _OutIter>::
> put(iter_type __s, ios_base& __io, char_type __fill, const tm* __tm,
> const _CharT* __beg, const _CharT* __end) const
>
> Looking at the symbol in libstdc++.so corresponding to the instantiation of
> time_put<char, std::ostreambuf_iterator<char, std::char_traits<char>>>, it
> is
>
> _ZNKSt8time_putIcSt19ostreambuf_iteratorIcSt11char_
> traitsIcEEE3putES3_RSt8ios_basePK2tmPKcSB_
>
> This corresponds to (according to c++filt):
>
> std::time_put<char, std::ostreambuf_iterator<char, std::char_traits<char> >
> > ::put(std::ostreambuf_iterator<char, std::char_traits<char> >,
> std::ios_base&, tm const*, char const*, char const*) const
>
> Now, linking the executable compiled with clang 5.0 results in an error
> about a missing symbol. That symbol is:
>
> std::time_put<char, std::ostreambuf_iterator<char, std::char_traits<char> >
> > ::put(std::ostreambuf_iterator<char, std::char_traits<char> >,
> std::ios_base&, std::tm const*, char const*, char const*) const
>
> where the difference is that the type tm is now std::tm.
>
> It seems to me that std::tm should be the proper type here, but I might be
> wrong.
>
> Comments?

This was done on purpose when we changed __cplusplus from 1 to 199711, to 
avoid breaking the ABI. On Solaris, we will mangle std::tm as if it was 
::tm until the next ABI break (probably not soon).

--
Marc Glisse