Control: severity -1 wishlist Hi,
Thanks for taking the time to file this!
On Wed, 07 Dec 2016 17:58:20 +0000, Riot <rain.back...@gmail.com> wrote:
> Experimental support is not currently enabled in Debian's build of the
> mingw-w64 cross-compiler.
I'm pretty sure it is: look
at
/usr/lib/gcc/{i686,x86_64}-w64-mingw32/6.2-{posix,win32}/include/c++/experimental
for the supported features.
> It's being used increasingly frequently for things like
> std::experimental::filesystem in a lot of projects, and is enabled by
> default in Debian's native g++. Mingw-w64's own upstream binary builds
> for Windows (such as "mingw-builds") all have experimental support enabled
> also.
>
> For consistency it would be very helpful to enable this in Debian's binary
> build, as this currently prevents cross-compiling a number of the same
> projects that compile fine with upstream's binary releases and with
> Debian's g++ binaries.
>
> The relevant flag to add is just configure --enable-experimental.
I haven't found any sign of an --enable-experimental option (the available
options are defined in libstdc++-v3/acinclude.m4 in the gcc source). For most
experimental (TS) features, no flag is required, they're enabled by default
if the target platform supports them; this is the case for MinGW-w64 Windows
targets. The only exception is the filesystem TS, which is only enabled by
default on POSIX systems where it's known to work (see
https://gcc.gnu.org/onlinedocs/libstdc++/manual/configure.html for details)
and requires --enable-libstdcxx-filesystem-ts; is that what you're after?
It's worth noting the caveats in
https://gcc.gnu.org/onlinedocs/libstdc++/manual/using_dynamic_or_shared.html#manual.intro.using.linkage.experimental
too.
Do you have an example project I could use to check that the Windows
implementation works? Although it currently fails to build, so enabling it
would probably take a bit of effort:
../../../../../../src/libstdc++-v3/src/filesystem/dir.cc: In function
'std::experimental::filesystem::v1::__cxx11::_Dir {anonymous}::open_dir(const
std::experimental::filesystem::v1::__cxx11::path&,
std::experimental::filesystem::v1::directory_options, std::error_code*)':
../../../../../../src/libstdc++-v3/src/filesystem/dir.cc:91:40: error: cannot
convert '_WDIR*' to 'DIR*' in initialization
if (DIR* dirp = ::opendir(p.c_str()))
^
../../../../../../src/libstdc++-v3/src/filesystem/dir.cc: In constructor
'std::experimental::filesystem::v1::__cxx11::recursive_directory_iterator::recursive_directory_iterator(const
std::experimental::filesystem::v1::__cxx11::path&,
std::experimental::filesystem::v1::directory_options, std::error_code*)':
../../../../../../src/libstdc++-v3/src/filesystem/dir.cc:249:38: error: cannot
convert '_WDIR*' to 'DIR*' in initialization
if (DIR* dirp = ::opendir(p.c_str()))
^
(I should probably check niXman's builds to see if there are any other
relevant options.)
Regards,
Stephen
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