[FFmpeg-devel,1/1] configure: use require_pkg_config to check for wavpack

Fixes static builds with toolchains needing "-lm" for math functions.

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
---
 configure | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

> Am 20.09.2020 um 13:52 schrieb Bernd Kuhls <bernd.kuhls@t-online.de>:
> 
> Fixes static builds with toolchains needing "-lm" for math functions.

Please don’t.

Why is this necessary? Doesn’t every FFmpeg link command contain -lm?

Carl Eugen

On Sun, Sep 20, 2020 at 3:34 PM Carl Eugen Hoyos <ceffmpeg@gmail.com> wrote:
>
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>
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> > Am 20.09.2020 um 13:52 schrieb Bernd Kuhls <bernd.kuhls@t-online.de>:
> >
> > Fixes static builds with toolchains needing "-lm" for math functions.
>
> Please don’t.
>

Please reword this in another way if your meaning is to note that
you'd like the configure option to still work without pkg-config.

I find pkg-config (or its less glib-dependant reimplementation,
pkgconf) to be great helpers, esp. when coupled with
PKG_CONFIG_{PATH,LIBDIR} (PATH appends, LIBDIR overrides) if you have
a custom prefix. So in my opinion the more pkg-config enabled checks
the better.

> Why is this necessary? Doesn’t every FFmpeg link command contain -lm?
>

"-lm" is only utilized in host_extralibs (and disabled in Haiku,
apparently), which is only utilized in `ffbuild/common.mak`. So when
you are doing configure checks you are going to be missing all of the
usual flags that you have not specifically specified in each and every
check.

That said, there is also a `libm` check_lib check which most likely
exports `libm_extralibs` as its result. It seems to be also utilized
in various checks where pkg-config is not utilized and the math
library was found to be required as part of the check.

Jan

Jan

On 9/20/2020 8:52 AM, Bernd Kuhls wrote:
> Fixes static builds with toolchains needing "-lm" for math functions.
> 
> Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
> ---
>  configure | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/configure b/configure
> index 5d68695192..4e6c6edd30 100755
> --- a/configure
> +++ b/configure
> @@ -6438,7 +6438,7 @@ enabled libvpx            && {
>      fi
>  }
>  
> -enabled libwavpack        && require libwavpack wavpack/wavpack.h WavpackOpenFileOutput  -lwavpack
> +enabled libwavpack        && require_pkg_config libwavpack wavpack "wavpack/wavpack.h" WavpackOpenFileOutput

For the sake of not breaking compilation with incomplete build
environments, add the pkg_config check while keeping the old check as a
fallback with the addition of $libm_extralibs after -lwavpack, which
should include -lm when present.

This means doing { check_pkg_config ... || require ... }, like with
libsmbclient.

>  enabled libwebp           && {
>      enabled libwebp_encoder      && require_pkg_config libwebp "libwebp >= 0.2.0" webp/encode.h WebPGetEncoderVersion
>      enabled libwebp_anim_encoder && check_pkg_config libwebp_anim_encoder "libwebpmux >= 0.4.0" webp/mux.h WebPAnimEncoderOptionsInit; }
>

Consider just not using libwavpack at all.
The ffmpeg native wavpack code has more features.

There even is a patch on this list for its removal.