qt5_make_output_file fails with build directories as symlinks

The qt5_make_output_file macro in Qt5CoreMacros.cmake does not generate the proper relative path when the build directory is a symlink. CMake currently does not resolve the build directory itself as a symlink, but instead uses an internal translation map to keep the directory it was reached as the "real path" for the build tree. This causes relative paths from the build directory into the source tree to be invalid (since the ../ traversal is off in the weeds when it is actually followed).

In general, relative paths between the source and build directories are not possible. Is there a reason that full, absolute paths are not used rather than relative paths?