Re: Shorter and less error-prone rule for automatic prerequisite generation in the GNU Make manual

[Edward Welbourne]

> If an update to new source code, that would compile just fine in a clean 
> checkout, breaks the incremental build, the build system is errornuous.

I would like to agree with you, but this constraint is, in general,
incompatible with incremental building, which is too good a benefit to
throw away.

> Anything that seeks to fix such bugs by user intervention is not a real
> solution. At least that is my opinion. I just don't know how that could be
> solved nicely in Make.

Quite.  In the mean time, we get as close to this ideal as possible
and we have clean-rules to purge selective chunks of what incremental
building normally caches for us, to deal with the messy cases.

If people *routinely need* to use any clean rule in the course of
their normal work-flows, I consider the build system inadequate: but
I'll still include clean rules for use when the exceptional situations
do come up (and as an aid to debugging).

        Eddy.