[FFmpeg-devel] [PATCH v2] configure: add -Wl when linker is called indirectly

[Kacper Michajlow]

On Fri, 20 Jun 2025 at 01:52, Kacper Michajłow <kasper93 at gmail.com> wrote:
>
> It's possible to call linker indirectly through driver like Clang. In
> which cases linker args has to be prefixed with -Wl.
>
> Signed-off-by: Kacper Michajłow <kasper93 at gmail.com>
> ---
>  configure | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/configure b/configure
> index c57da316cc..0dede08356 100755
> --- a/configure
> +++ b/configure
> @@ -5950,7 +5950,11 @@ case $target_os in
>          SLIB_INSTALL_LINKS=
>          SLIB_INSTALL_EXTRA_SHLIB='$(SLIBNAME:$(SLIBSUF)=.lib)'
>          SLIB_INSTALL_EXTRA_LIB='$(SLIBNAME_WITH_MAJOR:$(SLIBSUF)=.def)'
> -        SHFLAGS='-dll -def:$$(@:$(SLIBSUF)=.def) -implib:$(SUBDIR)$(SLIBNAME:$(SLIBSUF)=.lib)'
> +        if test $ld_type = "clang"; then
> +            SHFLAGS='-Wl,-dll -Wl,-def:$$(@:$(SLIBSUF)=.def) -Wl,-implib:$(SUBDIR)$(SLIBNAME:$(SLIBSUF)=.lib)'
> +        else
> +            SHFLAGS='-dll -def:$$(@:$(SLIBSUF)=.def) -implib:$(SUBDIR)$(SLIBNAME:$(SLIBSUF)=.lib)'
> +        fi
>          enabled x86_64 && objformat="win64" || objformat="win32"
>          ranlib=:
>          enable dos_paths
> --
> 2.45.1
>

Those two patches fixes those two FATE builds:

https://fate.ffmpeg.org/report.cgi?time=20250626214340&slot=amd64-clang-msvc
https://fate.ffmpeg.org/report.cgi?time=20250626214403&slot=amd64-clang-msvc-shared

SHFLAGS should really be safe as it is restricted to clang case only.
As for renaming static libs to .lib, I don't see a better way to just
rip the bandaid off. I understand it may require some small renaming
update for some users, but it keeps configure consistent with
expectations of llvm toolchain and generic Windows naming.

Thanks,
Kacper