Earlier quoted context omitted.
The big advantage of Make of course is that you can assume it is basically everywhere. I have just looked at tup, and it looks interesting, except I don't really understand why the auto-dependancy only kind-of works. If building X.c uses header.h, and header.h is created by script.sh, why do I have to tell tup about that ordering? Why can't it just see it has to run script.sh to get header.h, before building X.c?
The build system can't know beforehand which scripts generate which files (unless you're implying it ought to run everything that looks like it might be a script and observe what outputs it writes). However, once you've compiled a .c file the first time (or run the script the first time), the build system can remember which inputs and outputs were involved (either because gcc tells it which files it used, or by going…
I see the following warning about half way down the page. While I understand the first time this happens tup has an issue, I don't understand why it can't automatically remember it for future use (or does it?)
*** tup errors ***
tup error: Missing input dependency - a file was read from, and was not
specified as an input link for the command. This is an issue because the file
was created from another command, and without the input link the commands may
execute out of order. You should add this file as an input, since it is
possible this could randomly break in the future.