[qznc]

I have never before seen this idea to put CXXFLAGS into a file and treat it as a file dependency. That would also work with Make. Clever idea.

Nevertheless, a build system which does this implicitly is better, imho.

[apenwarr]

Perhaps unsurprisingly, djb seems to have pioneered this with his Makefiles, which generally produce, then depend on and run, a 'compile' script that contains the flags.