From: Jason Merrill <jason@redhat.com>
To: iain@sandoe.co.uk, gcc-patches@gcc.gnu.org
Subject: Re: [PATCH] c++, driver: Fix -static-libstdc++ for targets without Bstatic/dynamic.
Date: Thu, 22 Dec 2022 16:15:35 -0500 [thread overview]
Message-ID: <fafc6d9b-a479-e6af-c0a0-893ef7a6935d@redhat.com> (raw)
In-Reply-To: <20221204163047.72124-1-iain@sandoe.co.uk>
On 12/4/22 11:30, Iain Sandoe wrote:
> This fixes a long-standing problem on Darwin where we cannot independently set
> -static-libstdc++ because the flag gets stripped by the g++ driver.
>
> This patch is essentially the same as the one used for the 'D' driver and has
> been in local use for some time. It has also been tested on Linux.
>
> OK for master?
> backports?
> thanks
> Iain
>
> -- >8 --
>
> The current implementation for swapping between the static and shared c++
> runtimes relies on the static linker supporting Bstatic/dynamic which is
> not available for every target (Darwin's linker does not support this).
>
> Specs substitution (%s) is an alternative solution for this (which is what
> Darwin uses for Fortran, D and Objective-C). However, specs substitution
> requires that the '-static-libstdc++' be preserved in the driver's command
> line. The patch here arranges for this to be done when the configuration
> determines that linker support for Bstatic/dynamic is missing.
Would it work to define LIBSTDCXX_STATIC instead? If not, the patch is OK.
Really there should be a way for lang_specific_driver to mark a flag as
"validated" rather than prune it.
> Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>
>
> gcc/cp/ChangeLog:
>
> * g++spec.cc (lang_specific_driver): Preserve -static-libstdc++ in
> the driver command line for targets without -Bstatic/dynamic support
> in their static linker.
> ---
> gcc/cp/g++spec.cc | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/gcc/cp/g++spec.cc b/gcc/cp/g++spec.cc
> index 3d3b042dd56..f95d7965355 100644
> --- a/gcc/cp/g++spec.cc
> +++ b/gcc/cp/g++spec.cc
> @@ -234,7 +234,12 @@ lang_specific_driver (struct cl_decoded_option **in_decoded_options,
>
> case OPT_static_libstdc__:
> library = library >= 0 ? 2 : library;
> +#ifdef HAVE_LD_STATIC_DYNAMIC
> + /* Remove -static-libstdc++ from the command only if target supports
> + LD_STATIC_DYNAMIC. When not supported, it is left in so that a
> + back-end target can use outfile substitution. */
> args[i] |= SKIPOPT;
> +#endif
> break;
>
> case OPT_stdlib_:
next prev parent reply other threads:[~2022-12-22 21:15 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-04 16:30 Iain Sandoe
2022-12-22 19:14 ` [Ping^1] " Iain Sandoe
2022-12-22 21:15 ` Jason Merrill [this message]
2022-12-22 21:21 ` Iain Sandoe
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