pkg-config file is broken when CMAKE_INSTALL_{INCLUDE,LIB}DIR is absolute

[alexshpilkin]

As per title: CMakeLists.txt has

set(prefix ${CMAKE_INSTALL_PREFIX})
set(exec_prefix ${CMAKE_INSTALL_PREFIX})
set(includedir "\${prefix}/${CMAKE_INSTALL_INCLUDEDIR}")
set(libdir "\${prefix}/${CMAKE_INSTALL_LIBDIR}")

and so can’t handle absolute paths in CMAKE_INSTALL_{INCLUDE,LIB}DIR. This leads to broken .pc files on NixOS in particular. (Using prefix and not exec_prefix to derive libdir also seems a bit suspect, but is not the problem here.)

See “Concatenating paths when building pkg-config files” for a thorough discussion of the problem and a suggested fix, or KDE’s extra-cmake-modules for a simpler approach.

[recp]

Hi @alexshpilkin,

Thanks for reporting this, a PR to fix that would be awesome but I will take a look asap if none

[alexshpilkin]

I did not want to promise anything, but I could get around to fixing this in the end :) I’d appreciate it if you double-checked that I didn’t break anything.

[recp]

@alexshpilkin many thanks for the fix, it seems ok to me 🚀