Created attachment 186974 [details] [review]
0001-valac-Add-force-output.patch

When using valac as a code generator in Makefiles, make dependency
tracking becomes messed up if the timestamp of output files is not
updated when they are being rebuilt due to their dependencies being
newer. For example, whenever someclass.h is being rebuilt because
someclass.vala is newer, the timestamep of someclass.h must be updated
even if the file contents are unchanged.

Add a --force-output option to valac that if enabled makes valac
always generates an output file (thus updating its timestamp), even if
it already exists.