pkg-config file is broken when CMAKE_INSTALL_INCLUDEDIR is absolute

[alexshpilkin]

As per title: SPIRV-Headers.pc.in has

prefix=@CMAKE_INSTALL_PREFIX@
includedir=${prefix}/@CMAKE_INSTALL_INCLUDEDIR@

and so can’t handle absolute paths in CMAKE_INSTALL_INCLUDEDIR. This leads to broken .pc files on NixOS in particular.

Morally identical to KhronosGroup/SPIRV-Tools#3905. 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.

[johnkslang]

Is there a specific way you'd like to see this fixed, or do you have a PR you could propose?

[juan-lunarg]

CMAKE_INSTALL_INCLUDEDIR shouldn't be an absolute path. Or at least nothing in the CMake docs suggest setting CMAKE_INSTALL_INCLUDEDIR as an absolute path is valid.

[juan-lunarg]

Sorry turns out I was wrong. I'll make a PR to fix this for spirv-headers and spirv-tools.

Link to CMake docs:
https://cmake.org/cmake/help/latest/module/GNUInstallDirs.html

CMAKE_INSTALL_<dir>

Destination for files of a given type. This value may be passed to the DESTINATION options of install() commands for the corresponding file type. It should typically be a path relative to the installation prefix so that it can be converted to an absolute path in a relocatable way (see CMAKE_INSTALL_FULL_<dir>). However, an absolute path is also allowed.

The main line of focus being:

It should typically be a path relative to the installation prefix so that it can be converted to an absolute path in a relocatable way (see CMAKE_INSTALL_FULL_<dir>). However, an absolute path is also allowed.

[juan-lunarg]

Thanks for reporting this @alexshpilkin sorry for being wrong initially.

This is now fixed and tested as part of the CI process.