The type of file to return the filename for, when used with g_test_build_filename().
These two options correspond rather directly to the ‘dist’ and
‘built’ terminology that automake uses and are explicitly used to
distinguish between the ‘srcdir’ and ‘builddir’ being separate. All
files in your project should either be dist (in the
sense, in which case they will always be in the srcdir) or built (in
BUILT_SOURCES sense, in which case they will
always be in the builddir).
Note: as a general rule of automake, files that are generated only as part of the build-from-git process (but then are distributed with the tarball) always go in srcdir (even if doing a srcdir != builddir build from git) and are considered as distributed files.