Yes. "gcc -M" has various "features" that makes it completely useless for
any real dependancy generation.
- it's slow as molasses. I'm not talking "quite slow", I'm talking "so
slow that it's pretty much useless for any reasonably sized program".
It's essentially only useful for batch-processing.
- it doesn't know about configuration dependencies (ie the things that
mkdep does to warn you when the config file hasn't been properly
included)
- it actually parses C preprocessor stuff (notably #ifdef), and because
of that it often leaves out critical dependency information (and it
_requires_ that you know all of the configuration at mkdep time).
- it will do recursive dependencies (exactly because it parses the C
file), which is extremely inefficient (that's the whole point on having
"make" in the first place - to keep track of complex dependencies).
It becomes even more useless when trying to make a more intelligent
configuration setup.
Linus