[cfe-dev] Clang++ always defines _GNU_SOURCE

[Eric Fiselier via cfe-dev]

>  Does libc++ also rely on this macro to work on Linux?

Yes. Adding -U_GNU_SOURCE during the libc++ build results in a litany of
errors.
The libc++ headers depend on a number of C library symbols that only get
defined when -D_GNU_SOURCE=1 is present.

/Eric

On Tue, Jun 14, 2016 at 2:40 AM, Lei Zhang via cfe-dev <
cfe-dev at lists.llvm.org> wrote:

> Hi,
>
> I noticed that clang++ unconditionally defines _GNU_SOURCE on Linux,
> even when I'm not including any headers in my code. Switching from
> stdlibc++ to libc++ doesn't change this, either.
>
> I understand that g++ does this because stdlibc++ heavily relies on
> _GNU_SOURCE. But what is the reason for clang++ to do so when using
> libc++? Does libc++ also rely on this macro to work on Linux?
>
>
> Regards,
> Lei
> _______________________________________________
> cfe-dev mailing list
> cfe-dev at lists.llvm.org
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>
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