autoantwort
commented
3 years ago The corrent solution is to create an own triplet and set VCPKG_CHAINLOAD_TOOLCHAIN_FILE (The compiler selected by cmake will be passed to every other build system)
Closed Toxe closed 2 years ago
autoantwort
commented
3 years ago The corrent solution is to create an own triplet and set VCPKG_CHAINLOAD_TOOLCHAIN_FILE (The compiler selected by cmake will be passed to every other build system)
dg0yt
commented
3 years ago The corrent solution is to create an own triplet and set VCPKG_CHAINLOAD_TOOLCHAIN_FILE (The compiler selected by cmake will be passed to every other build system)
AFAIU this the correct solution for generally forcing a particular compiler.
However, if all dependencies of ffmpeg build well, and in particular if cmake finds a compiler, then port ffmpeg should perhaps pass the cmake detected compiler to the build script?
Toxe
commented
3 years ago However, if all dependencies of ffmpeg build well, and in particular if cmake finds a compiler, then port ffmpeg should perhaps pass the cmake detected compiler to the build script?
As far as I can tell everything else that Vcpkg does behind the scenes works flawlessly (including the compiler detection bit) which is why I was so confused that it does not pass my compiler to the FFmpeg configure script.
Toxe
commented
3 years ago The corrent solution is to create an own triplet and set VCPKG_CHAINLOAD_TOOLCHAIN_FILE (The compiler selected by cmake will be passed to every other build system)
I never worked with toolchains or custom triplets before and so far this does not work at all for me. I cannot even get beyond the detect compiler step and always get a "No CMAKE_CCOMPILER could be found" error. But honestly even if it would work I am not sure that it would change anything because it still looks to me that my `CMAKE*_COMPILER` settings are just not passed down to the actual FFmpeg configure script.
NancyLi1013
commented
3 years ago @mcmtroffaes Do you have any suggestion for this problem?
Thanks.
mcmtroffaes
commented
3 years ago At the moment, to the best of my understanding, the ffmpeg configure script simply autodetects the compiler from the environment, and it's quite possible that this doesn't work the same way as with other vcpkg packages. So, explicitly passing CMAKE_*_COMPILER via --cc and --ccx flags to the ffmpeg configure script to ensure the same compiler is used as with other packages feels like the right approach.
Toxe
commented
3 years ago At the moment, to the best of my understanding, the ffmpeg configure script simply autodetects the compiler from the environment, and it's quite possible that this doesn't work the same way as with other vcpkg packages. So, explicitly passing CMAKE_*_COMPILER via --cc and --ccx flags to the ffmpeg configure script to ensure the same compiler is used as with other packages feels like the right approach.
This is how that configure call (line 94 in ports/ffmpeg/build.sh.in) should look like in my case:
sh "$PATH_TO_SRC_DIR/configure" "--prefix=$PATH_TO_PACKAGE_DIR" --cc=/usr/bin/gcc-11 --cxx=/usr/bin/g++-11 @CONFIGURE_OPTIONS@ $@Is there any "official" way (like some Vcpkg flags) to get the --cc and --cxx options into @CONFIGURE_OPTIONS@? Or would I need to modify this file anytime I want to use a different compiler?
mcmtroffaes
commented
3 years ago The build.sh script is created from build.sh.in by the portfile; see https://github.com/microsoft/vcpkg/blob/master/ports/ffmpeg/portfile.cmake. Instead of using those options, however, it might also be possible to experiment with setting CC and CCX. I just noticed that this is how the CFLAGS etc. are set:
https://github.com/microsoft/vcpkg/blob/master/ports/ffmpeg/portfile.cmake#L639
So for consistency, I guess the compiler could also be set this way, at least if the configure script will then look for these settings (I suspect it will). If that fails, --cc and --cxx should work i.e. through
set(OPTIONS "${OPTIONS} --cc=...")
set(OPTIONS "${OPTIONS} --cxx=...")at any point prior to https://github.com/microsoft/vcpkg/blob/master/ports/ffmpeg/portfile.cmake#L633
Toxe
commented
3 years ago Setting CC and CXX does not work at the moment, which is my issue. Normally I would call something like:
$ CC=/usr/bin/gcc-11 CXX=/usr/bin/g++-11 ./vcpkg install ffmpeg
But neither the portfile nor the build.sh script respect these settings, and the actual FFmpeg configure script ignores these as well. The output from the FFmpeg configure script does confirm that it actually sees the CC and CXX flags, it just does nothing with those values and ignores them and always just tries plain old gcc. Well, unless we pass in the compiler via the configure --cc=[..] --cxx=[..] options.
I feel like the proper solution would be to update the portfile so that it checks if CC or CXX are set (like it already does for CFLAGS/CXXFLAGS) and then update OPTIONS, as you have shown.
mcmtroffaes
commented
3 years ago Well, I think that the portfile ought to pass CMAKE_C_COMPILER and CMAKE_CXX_COMPILER to the configure script, since that's what the toolchain files use. This will fix situations where potentially compilers get mixed if more than one compiler is installed. But I'm not sure if CC/CXX should be detected at toolchain level or not. Do you know if CMAKE_C_COMPILER gets set to your desired compiler if you call vcpkg with CC=... ./vcpkg ...? If it does, then this will fix also your issue. If it does not, maybe a wider discussion is needed as to what is the correct approach, i.e. whether this needs fixing in the portfile or somewhere else in the vcpkg internal code.
Toxe
commented
3 years ago Sorry, you are right, I actually meant checking if CMAKE_C_COMPILER and CMAKE_CXX_COMPILER are set in the portfile instead of looking for CC/CXX. My bad.
Do you know if CMAKE_C_COMPILER gets set to your desired compiler if you call vcpkg with
CC=... ./vcpkg ...?
CMAKE_C_COMPILER is empty in the portfile. Only value I could find that is set was $ENV{CC}. But I'm no expert here and have no idea what values should be available at this stage. Honestly I expected that CMAKE_C_COMPILER would be filled by now but that does not seem to be the case.
If I add the following to the portfile I can build FFmpeg just fine when calling: $ CC=/usr/bin/gcc-11 CXX=/usr/bin/g++-11 ./vcpkg install ffmpeg:
if(DEFINED ENV{CC})
set(OPTIONS "${OPTIONS} --cc=$ENV{CC}")
endif()
if(DEFINED ENV{CXX})
set(OPTIONS "${OPTIONS} --cxx=$ENV{CXX}")
endif()Unless there is a better solution I would suggest adding something like that to the portfile for the time being.
mcmtroffaes
commented
3 years ago Many thanks for running some tests. To me, your suggested patch looks like a very reasonable way solve your problem.
I fear that I don't understand why CMAKE_C_COMPILER and CMAKE_CXX_COMPILER are not set in the portfile... It would be great to get some input from someone who better understands the vcpkg compiler detection mechanics, and to see if there's a better solution than just passing on $ENV{CC} to the configure script.
dg0yt
commented
3 years ago I fear that I don't understand why CMAKE_C_COMPILER and CMAKE_CXX_COMPILER are not set in the portfile..
See the end of the maintainer's guide: Portfiles run in script mode. There is no configuration for any language or similar. Vcpkg has internal maintainer functions to get cmake configuration into portfiles when needed: https://github.com/microsoft/vcpkg/blob/master/docs/maintainers/internal/z_vcpkg_get_cmake_vars.md Normally this is used by other maintainer functions, but ffmpeg doesn't use a standard configuration function.
mcmtroffaes
commented
3 years ago Thanks @dg0yt. That function is actually called here: https://github.com/microsoft/vcpkg/blob/master/ports/ffmpeg/portfile.cmake#L547 Would VCPKG_DETECTED_CMAKE_C_COMPILER work? If so, should we use it?
dg0yt
commented
3 years ago I think you can take inspiration from vcpkg_configure_make. Usually it takes a few more variables, e.g. for flags, linker etc. Only with a complete and consistent set it will work for native builds, cross builds, different osx CPUs...
Neumann-A
commented
2 years ago @JackBoosY can be closed. Should be fixed since the port now sets CC
Host Environment
To Reproduce
gcc.CC=/usr/bin/gcc-11 CXX=/usr/bin/g++-11 ./vcpkg install ffmpegFailure logs
Additional context How can I build FFmpeg with a compiler other than
gcc?I do not have
gccandg++symlinks on my system (which has never been an issue) but instead I want to manually specify the compiler when installing a new package. For years I have done something like this (or used equivalent settings from VSCode, which is important for switching compiler kits):CC=/usr/bin/gcc-11 CXX=/usr/bin/g++-11 ./vcpkg install [...]This has always been fine. But now I have an issue with FFmpeg. Looks like it always wants to use
gcc, no matter if I supply a compiler on my call tovcpkg installor not.Which raises the question: Is it even possible to compile FFmpeg (via Vcpkg) with anything other than GCC? What would be the proper way to specify the compiler when installing a new package? I feel like I am missing something here.
vcpkg\buildtrees\ffmpeg\build-x64-linux-rel-out.log:Bottom of
vcpkg\buildtrees\ffmpeg\x64-linux-rel\ffbuild\config.log:How to fix this First of all, if I define
gccandg++symlinks to GCC 11 everything works fine. But that's not really the point, because how would anyone use a different compiler to build FFmpeg?I can pass through the options
--cc=/usr/bin/gcc-11and--cxx=/usr/bin/g++-11to the FFmpeg configure script from the fileports/ffmpeg/build.sh.in(line 94) and that would allow me to build FFmpeg with a different compiler other thangcc:Now I only need a way to pass these options to
ports/ffmpeg/build.sh.in. Basically the portfile should check if$CCor$CXXare defined and then add these options to the call of the FFmpeg configure script, I suppose? Would that be the way to go? Should I make a PR and add these? I'm just a bit puzzled that something like this isn't already possible and I feel like I am missing something on a very fundamental level.