A nitpick, but I don't think that should really be called caching, although it kind of is, in a looser sense. It's just comparing the file timestamps of the .o and .c files, and building the .o from the .c, if the .c is newer, or if the .o doesn't exist.
I mean it’s caching using a key derivation scheme which uses file names rather than file contents. It might not be sophisticated caching but it is caching.
A nitpick, but I don't think that should really be called caching, although it kind of is, in a looser sense. It's just comparing the file timestamps of the .o and .c files, and building the .o from the .c, if the .c is newer, or if the .o doesn't exist.