PATCH: Remove generated YACC stuff

[Alexandre Oliva]

On Jul 29, 2000, Mark Mitchell <mark@codesourcery.com> wrote:

>   $(srcdir)/c-parse.y $(srcdir)/objc-parse.y: c-parse.in

> If make decides to build both c-parse.y and objc-parse.y at once,
> craziness ensues.  I'll fix this up as best I can.

The only sane way to deal with such multi-target rules in the context
of parallel makes is to use a timestamp file.  Something like:

$(srcdir)/c-parse.y $(srcdir)/objc-parse.y: stamp-cparse
# Ensure that, if one of the built files is removed, ensure that
# they'll be built next time.  This build will fail, though.
        @test -f $@ || rm -f stamp-cparse

stamp-cparse: $(srcdir)/c-parse.in
        ... # Build the *-parse.y files
        @echo timestamp > $@


Unfortunately, this means we'd have to include the stamp file in the
distribution or perform a poor man's dependency test in order to
decide whether to re-generate the files even if it is only the stamp
file that's missing.  Something like (untested):

        # If both generated files exist and are newer than the input...
        if x`ls -1t $(srcdir)/c-parse.in \
                    $(srcdir)/c-parse.y $(srcdir)/objc-parse.y | \
             sed -n 3p` = x$(srcdir)/c-parse.in; then
          ... # Build both of them
        fi
        @echo timestamp > $@

-- 
Alexandre Oliva   Enjoy Guarana', see http://www.ic.unicamp.br/~oliva/
Red Hat GCC Developer                  aoliva@{cygnus.com, redhat.com}
CS PhD student at IC-Unicamp        oliva@{lsd.ic.unicamp.br, gnu.org}
Free Software Evangelist    *Please* write to mailing lists, not to me