[SOLVED] Link X11 using BUCK build for a CPP application

Link X11 using BUCK build for a CPP application

Im having issues trying to compile a CPP application with a dependency on X11 using buck as it appears to not be linking the X11 Lib and results in an undefined reference error:

 undefined reference to `XOpenDisplay'
collect2: error: ld returned 1 exit status

After researching the error I tried to modify the BUCK file to provide the correct flags and tried in a few different formats:

  platform_linker_flags = [
   # ('^linux.*', ['-lX11','-L/usr/X11/lib','-I/opt/X11/include'])
    ('^linux.*', []),
    ('^linux.*', ['-lX11']),
    ('^linux.*', ['-L/usr/X11/lib']),
  ],

I tried as you can see above to change the structure etc to see if it made a difference in the linking process however it still does not resolve the dependency required for XOpenDisplay.

Can anyone possibly explain or reference the correct way to apply system libs to a buck project or allude to what may be going wrong in this build.

Solution

Try to create a "dummy" target for the system library:

prebuilt_cxx_library(
  name = 'x11', 
  header_only = True,
  exported_platform_linker_flags = [
    ('linux.*', [ '-lX11' ]),
  ],
)

cxx_library(
  name = 'foo',
  srcs = glob([
    '**/*.cpp',
  ]),
  deps = [
    ':x11',
  ],
)

This is the approach used by Buckaroo

There was some discussion of this here: https://github.com/facebook/buck/issues/1443