Re: Checking for built files

[Brooks Moses]

Andrej Prsa wrote:
> a program I am working on consists of fortran sources that are compiled
> with f2c into their C counterparts, linked into a shared library and
> then used in the remainder of the program. To facilitate compiling, I
> thought of distributing f2c'd C sources in the tarball so that the
> users don't need to have f2c installed to compile the code. However, if
> someone did `make distclean`, all built C sources would be deleted and
> f2c then must be present on a system. What would be a good way to check
> for the existence of built sources and to check for f2c in case these
> sources are missing?

For what it's worth, I think one notable failure there is that "make 
distclean" should not delete the built C sources, if you expect them to 
be part of the distribution!

What we do for similar things (and this is also done in GCC, for 
example) is to define an --enable-maintainer-mode option.  When 
maintainer-mode is disabled, which in the default case, configure will 
generate a makefile that assumes that things like your generated C files 
are already present in the source tree, and it does not try to rebuild 
them.  When maintainer mode is enabled, the system will assume that you 
want these sources included in the makefile, and thus they'll get 
rebuilt if they're not present or are older than the corresponding 
Fortran files.

Note that this means that, when maintainer-mode is enabled, the makefile 
must generate the C sources in the _source_ tree, not the _build_ tree, 
in order for things to work correctly.  But you have to deal with that 
problem anyway, if they might or might be part of the distribution....

(In any case, if you just want to do things exactly as you described, a 
simple AC_CHECK_PROGS(F2C, f2c) and then an "if test ! -f $(filename)" 
block surrounding some code that throws an error if the F2C variable is 
empty will do what you want.)

- Brooks