https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125956
--- Comment #8 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Jonathan Wakely from comment #7)
> --- a/libstdc++-v3/src/c++20/format.cc
> +++ b/libstdc++-v3/src/c++20/format.cc
> @@ -93,6 +93,19 @@ struct __encoding : locale::facet
> #ifdef _GLIBCXX_HAVE_ICONV
> ::iconv_t _M_cd = (::iconv_t)-1;
> mutable mutex mx;
> +
> +
> + // This adaptor works around the signature problems of the second
> + // argument to iconv(): SUSv2 and others use 'const char**', but glibc
> 2.2
> + // uses 'char**', which matches the POSIX 1003.1-2001 standard.
> + // Using this adaptor, we deduce the correct type from the function
> pointer
> + // and then cast the `inbuf` parameter to that type.
> + template<typename T>
> + size_t
> + do_iconv(size_t (*func)(iconv_t, T, size_t*, char**, size_t*),
> + char** inbuf, size_t* inbytes,
> + char** outbuf, size_t* outbytes)
> + { return ::iconv(_M_cd, (T)inbuf, inbytes, outbuf, outbytes); }
> #endif
>
> // Convert `input` to UTF-8, using `out` to hold the result.
> @@ -115,8 +128,7 @@ struct __encoding : locale::facet
> = const_cast<char*>(input.data()) + input.size() - inbytesleft;
> char* outbytes = p + written;
> size_t outbytesleft = n - written;
> - size_t res = ::iconv(_M_cd, &inbytes, &inbytesleft,
> - &outbytes, &outbytesleft);
> + size_t res = do_iconv(&inbytes, &inbytesleft, &outbytes,
> &outbytesleft);
Oops, this needs ::iconv passed as the first argument.
But I have a better idea anyway.
