If you want to be able to build the vala package with modified sources, I see only two ways how to achieve that. Either build-depend the package on (an earlier version of) valac or also apply the updated .c files with the patch. I strongly recommend the former as it avoids timestamp issues and it is probably what is done for other self-hosting compilers such as gcc as well.
If you want to be able to build the vala package with modified sources, I see only two ways how to achieve that. Either build-depend the package on (an earlier version of) valac or also apply the updated .c files with the patch. I strongly recommend the former as it avoids timestamp issues and it is probably what is done for other self-hosting compilers such as gcc as well.