ffmpeg on Windows is currently exporting malformed .pc files.

[traversaro]

Describe the bug
ffmpeg on Windows is currently exporting malformed .pc files.

Environment

• OS: Windows/Linux
• Compiler: Not relevant

To Reproduce
Steps to reproduce the behavior:

1. ./vcpkg install ffmpeg
2. Inspect the installed .pc files

Expected behavior
ffmpeg should install well formed .pc files.

Failure logs
See #11273 (comment) .

Additional context
Originally discussed in #11273 (comment), but I opened a separate issue for better visibility. This is a specific instance of the more general problem discussed in #11103 .

[traversaro]

do you think it is sufficient to add ole32 and user32 to the system libraries?

you can probably add all windows standard libraries as system libraries.

Thanks @Neumann-A ! The strange thing is that apparently the library are not listed as -lole32, but just as ole32.lib, see:

Name: libavdevice
Description: FFmpeg device handling library
Version: 58.8.100
Requires: 
Requires.private: libavfilter >= 7.57.100, libswscale >= 5.5.100, libavformat >= 58.29.100, libavcodec >= 58.54.100, libswresample >= 3.5.100, libavresample >= 4.0.0, libavutil >= 56.31.100
Conflicts:
Libs: -L${libdir}  -lavdevice 
Libs.private: psapi.lib ole32.lib strmiids.lib uuid.lib oleaut32.lib shlwapi.lib gdi32.lib vfw32.lib
Cflags: -I${includedir}

do you think that is a case that is supported in pkg-config, or it is just that ffmpeg produces malformed .pc files?
``
I tried to add all the library names (such as psapi.lib, `strmiids.lib` to the `IGNORE_FLAGS` of `vcpkg_fixup_pkgconfig` ), but this is not working as the content of `Libs.private` is considered as a unique string, in fact the error in #11273 (comment) is

CMake Error at scripts/cmake/vcpkg_fixup_pkgconfig.cmake:150 (message):
  Found ole32.lib user32.lib and no rule to analyse the flag! Please check
  the *.pc file

and not for ole32.lib and user32.lib separately.

[Neumann-A]

You probably need to wait for the PR using pkg-config for the checks.

[traversaro]

The simple use of vcpkg_fixup_pkgconfig for ffmpeg:x64-osx is failing as well:

CMake Error at scripts/cmake/vcpkg_fixup_pkgconfig.cmake:130 (message):
  Library iconv was not found! If it is a system library use the
  SYSTEM_LIBRARIES parameter for the vcpkg_fixup_pkgconfig call! Otherwise,
  corret the *.pc file
Call Stack (most recent call first):
  scripts/cmake/vcpkg_fixup_pkgconfig.cmake:234 (vcpkg_fixup_pkgconfig_check_libraries)
  ports/ffmpeg/portfile.cmake:293 (vcpkg_fixup_pkgconfig)
  scripts/ports.cmake:76 (include)

See the CI for #11273, in particular https://github.com/microsoft/vcpkg/pull/11273/checks?check_run_id=862778528 .

[Neumann-A]

I don't think that is a failure of vcpkg_fixup_pkgconfig knowing that iconv is only build on windows and nowhere else

[traversaro]

Related PR: #13919 .

[Be-ing]

There have been several PRs that seem related to this issue in the past several months, but using pkg_check_modules is still failing:

CMake Error at C:/Program Files (x86)/Microsoft Visual Studio/2019/Enterprise/Common7/IDE/CommonExtensions/Microsoft/CMake/CMake/share/cmake-3.18/Modules/FindPkgConfig.cmake:75 (set):
  Syntax error in cmake code at

    C:/Program Files (x86)/Microsoft Visual Studio/2019/Enterprise/Common7/IDE/CommonExtensions/Microsoft/CMake/CMake/share/cmake-3.18/Modules/FindPkgConfig.cmake:75

  when parsing string

    \a\mixxx\mixxx\build\vcpkg_installed\x64-windows\lib\pkgconfig/../..

  Invalid character escape '\a'.
Call Stack (most recent call first):
  C:/Program Files (x86)/Microsoft Visual Studio/2019/Enterprise/Common7/IDE/CommonExtensions/Microsoft/CMake/CMake/share/cmake-3.18/Modules/FindPkgConfig.cmake:102 (_pkgconfig_set)
  C:/Program Files (x86)/Microsoft Visual Studio/2019/Enterprise/Common7/IDE/CommonExtensions/Microsoft/CMake/CMake/share/cmake-3.18/Modules/FindPkgConfig.cmake:828 (_pkgconfig_invoke)
  C:/Program Files (x86)/Microsoft Visual Studio/2019/Enterprise/Common7/IDE/CommonExtensions/Microsoft/CMake/CMake/share/cmake-3.18/Modules/FindPkgConfig.cmake:564 (pkg_get_variable)
  C:/Program Files (x86)/Microsoft Visual Studio/2019/Enterprise/Common7/IDE/CommonExtensions/Microsoft/CMake/CMake/share/cmake-3.18/Modules/FindPkgConfig.cmake:733 (_pkg_check_modules_internal)
  cmake/modules/FindFFMPEG.cmake:82 (pkg_check_modules)
  cmake/modules/FindFFMPEG.cmake:124 (find_component)
  build/vcpkg_installed/x64-windows/share/ffmpeg/vcpkg-cmake-wrapper.cmake:4 (_find_package)
  vcpkg/scripts/buildsystems/vcpkg.cmake:597 (include)
  CMakeLists.txt:2252 (find_package)

[mcmtroffaes]

As a side effect of #17985 (which has just been merged), pkg_check_modules seems to be working now. Is anyone still seeing issues?

[JackBoosY]

This issue should be fixed, please reopen this issue if it still bother you.

[traversaro]

Thanks a lot @JackBoosY @mcmtroffaes !