[FFmpeg-trac] #9916(build system:new): Poor/misleading diagnostics on pkg-config error

[FFmpeg]

#9916: Poor/misleading diagnostics on pkg-config error
-------------------------------------+-------------------------------------
             Reporter:  David von    |                    Owner:  (none)
  Oheimb                             |
                 Type:  defect       |                   Status:  new
             Priority:  important    |                Component:  build
                                     |  system
              Version:  git-master   |               Resolution:
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
Description changed by David von Oheimb:

Old description:

> Running ./configure, when anything goes wrong with a dependency lib, one
> just gets something like
>
> {{{
> ERROR: x265 not found using pkg-config
> }}}
>
> and it can be extremely hard guessing what went wrong. Then users
> typically resort to asking in forums like this:
> https://stackoverflow.com/questions/51918409/compiling-ffmpeg-x265-not-
> found-using-pkg-config and in my case all those hints did not help.
>
> Eventually I dug into the "configure" file and found that
> pkg_config_fail_message is usually empty, but there is a file
> ffbuild/config.log that contains a lot of detail. In this case, the test
> compilation of libx265 went wrong with errors like
>
> {{{
>    undefined reference to `__pow_finite'
> }}}
>
> so the error "x265 not found" is pretty misleading.
>
> In case configuration goes wrong, you should at least point users to
> having a look at ffbuild/config.log
>
> I flag this ticket as 'important' because unfortunately it happens way
> too often that users have trouble with "configure" and are pretty lost.
> This typically causes major frustration and loss of time.

New description:

 Running `./configure`, when anything goes wrong with a dependency lib, one
 just gets something like

 {{{
 ERROR: x265 not found using pkg-config
 }}}

 and it can be extremely hard guessing what went wrong. Then users
 typically resort to asking in forums like this:
 https://stackoverflow.com/questions/51918409/compiling-ffmpeg-x265-not-
 found-using-pkg-config and in my case all those hints did not help.

 Eventually I dug into the `configure` file and found that
 `pkg_config_fail_message` is usually empty, but there is a file
 `ffbuild/config.log` that contains a lot of detail. In my case, the test
 compilation using `libx265` went wrong with errors like

 {{{
    undefined reference to `__pow_finite'
 }}}

 so the error "x265 not found" is pretty misleading.

 In case configuration goes wrong, you should at least point users to
 having a look at `ffbuild/config.log`

 I flag this ticket as 'important' because unfortunately it happens way too
 often that users have trouble with "configure" and are pretty lost. This
 typically causes major frustration and loss of time.

--
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Ticket URL: <https://trac.ffmpeg.org/ticket/9916#comment:2>
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