[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    |                     Type:  defect
  Oheimb                             |
               Status:  new          |                 Priority:  important
            Component:  build        |                  Version:  git-
  system                             |  master
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 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.
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/9916>
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