[ffmpeg] regxep and passthrough fix

[petersteneteg]

This PR addresses issues with building FFMpeg on windows

The PC config files are transform in the portfile:

vcpkg/ports/ffmpeg/portfile.cmake

Lines 856 to 861 in 735bf69

	if(content MATCHES "${entry}: ([^\n]*)")
	set(old_value "${CMAKE_MATCH_1}")
	string(REGEX REPLACE "-libpath:" "-L" new_value "${old_value}")
	string(REGEX REPLACE " ([^ /]+)[.]lib" " -l\\1" new_value "${new_value}")
	string(REPLACE "${entry}: ${old_value}" "${entry}: ${new_value}" content "${content}")
	endif()

basically mapping foo.lib -> -lfoo
But first case item in the list was not transformed due to a space issue in the regexp matching

for example: given input:
Libs.private: psapi.lib ole32.lib strmiids.lib uuid.lib
We got
Libs.private: psapi.lib -lole32 -lstrmiids -luuid
But expected
Libs.private: -lpsapi -lole32 -lstrmiids -luuid

Similarly
In the generated FindFFMPEG.cmake I get the following in my windows computer

append_dependencies(FFMPEG_DEPS_LIBRARY_RELEASE NAMES "psapi.lib;uuid.lib;oleaut32.lib;shlwapi.lib;gdi32.lib;vfw32.lib;secur32.lib;ws2_32.lib;mfuuid.lib;strmiids.lib;ole32.lib;user32.lib;bcrypt.lib")

And we expect libs like psapi.lib the math the set of pass_through libs

vcpkg/ports/ffmpeg/FindFFMPEG.cmake.in

Lines 56 to 60 in 735bf69

	set(pass_through
	${CMAKE_CXX_IMPLICIT_LINK_LIBRARIES}
	advapi32 bcrypt crypt32 gdi32 mfuuid ole32 oleaut32 psapi secur32 shlwapi strmiids user32 uuid vfw32 ws2_32 usp10 cfgmgr32 rpcrt4
	-pthread -pthreads pthread atomic m
	)

But since they are given without the .lib extension we also have to check just the stem of the give lib name

• Changes comply with the maintainer guide.
• SHA512s are updated for each updated download.
• The "supports" clause reflects platforms that may be fixed by this new version.
• Any fixed CI baseline entries are removed from that file.
• Any patches that are no longer applied are deleted from the port's directory.
• The version database is fixed by rerunning ./vcpkg x-add-version --all and committing the result.
• Only one version is added to each modified port's versions file.

[BillyONeal]

The build failures appear legitimate.

[petersteneteg]

@BillyONeal Yes, probably, But I can not reproduce it locally and it seems I can not download the build logs from the failed jobs. The download buttons don't seem do anything. How can I access them?

[BillyONeal]

failure logs for x64-windows-static.zip

Button works for me 🤷

[BillyONeal]

(Note that vcpkg-ci-ffmpeg is in scripts/test_ports)

[dg0yt]

libpath woes?

• Both failures do not show a single -libpath in the failing linker command.
• Some libs are used with namespec only (failing: SDL2-staticd.lib, libmfx.lib).
• The pattern which this PR attempts to fix is also related to the lack of libpath: The usual haystack is

  Libs: <libpath-arg> <lib-arg> [...]
  

  There is hardly any scenario where a pc file wouldn't use this pattern. And then the modification wouldn't be needed. (The exception might be header-only "libs" if they need system libs. But here, we look at ffmpeg.)

[petersteneteg]

@BillyONeal I only found this page with artifacts https://dev.azure.com/vcpkg/public/_build/results?buildId=114494&view=artifacts&pathAsName=false&type=publishedArtifacts and not of those works, Where do I find the link you added?

Im using firefox as you see the three vertical dot that I can see in Safari is not there on firefox. And clicking the text does noting. But I found that after some hovering I can get the dots to pop up so I can get to the download button.

[petersteneteg]

@dg0yt I don't quite understand what the problem is or how I caused it. :/ And locally everything works. Do you have any more hints on how to address the issues?

[dg0yt]

Can you start with information how to reproduce the problem? Which feature set or manifest do you use when the problem occurs?

[dg0yt]

Where do I find the link you added?

Hover an artifact line. Spot the three dots on the right side while hovering.