I've written a variant of the Program Builder which has a problem: it doesn't pick its targets from the cache when it should.
I've tried adding the flags --warn=target-not-built and --debug=explain without success in explaining what is wrong.
Are there any flags or techniques that can help me find the reason to why the Builder doesn't reuse the cache?
Try "scons --cache-debug=-" (see SCons' MAN page), which should give you some messages about the files that the cache gets probed for and such.