Re: -stdlib=libc++?

[Shivam Gupta <shivam98.tkg@gmail.com>]

Hi Iain,

Thank you for the quick response and the effort to make that feature
available.

When I reconfigured/build GCC
with --with-gxx-libcxx-include-dir=/usr/include/c++/v1/ , -stdlib= option
is now available to take libc++.

thanks,
Shivam.

On Sat, Apr 2, 2022 at 3:21 PM Iain Sandoe <iain@sandoe.co.uk> wrote:

> Hi Shivam,
>
> > On 2 Apr 2022, at 06:57, Shivam Gupta <shivam98.tkg@gmail.com> wrote:
> >
> > I saw your last year's mail for the same topic on the GCC mailing list -
> https://gcc.gnu.org/pipermail/gcc/2020-March/000230.html.
>
> The patch was applied to GCC-11 (so is available one GCC-11 branch and
> will be on GCC-12 when that is released).
> >
> > I tried today but this option is still not available.
>
> The option has to be configured when the compiler is built, that also
> means that you have to install (and point the configure to) a suitable set
> of libc++ headers from the LLVM project  (e.g. there is a set here:
> https://github.com/iains/llvm-project/tree/9.0.1-gcc-stdlib).
>
> Generally, GCC is very compatible with the libc++ headers (the changes I
> made on that branch were mostly to deal with <coroutine> being in std:: for
> GCC and std::experimental:: for LLVM-9).  For LLVM libc++ earlier than 9
> there is a missing symbol that GCC uses - but that can be worked around too.
>
> There have been some changes in more recent (in particular, LLVM-14/main)
> libc++ that should make it more compatible.
>
> Of course, you should pick a version of the libc++ headers than matches
> the version used on your system (9 was used for quite a long time, but
> recent xcode headers are newer).
>
> Given that this involves cross-project sources and choosing a suitable
> set, probably it is a job for the distributions (e.g. homebrew, macports
> etc) to arrange or, for self-built compilers, following in the general
> comments above.
>
> FWIW, I have used this to build quite a few OSS projects on a number of
> Darwin versions (hence the comment about GCC being very compatible with
> libc++).
>
> thanks,
> Iain.
>
>