There are actually several ways for a build tool like Automake to cause tools to generate dependencies.
This was a commonly-used method in the past. The idea is to run a
special program over the source and have it generate dependency
information. Traditional implementations of
not completely precise; ordinarily they were conservative and
discovered too many dependencies.
An obvious way to generate dependencies is to simply write the tool so that it can generate the information needed by the build tool. This is also the most portable method. Many compilers have an option to generate dependencies. Unfortunately, not all tools provide such an option.
It is possible to write a special file system that tracks opens,
reads, writes, etc, and then feed this information back to the build
clearmake does this. This is a very powerful
technique, as it doesn’t require cooperation from the
tool. Unfortunately it is also very difficult to implement and also
not practical in the general case.
Rather than use the file system, one could write a special library to
open and other syscalls. This technique is also quite
powerful, but unfortunately it is not portable enough for use in