Fix generating bison output for pars.y

[ccawley2011]

The generated pars.c file requires the header file specified by the --defines argument, but it's renamed before the source file can be compiled.

[th-otto]

I recently changed that rule for a simple reason: if you let the rule write directly to pars.h, then pars.c might be compiled before bison is finished writing pars.h when you run parallel makes, and then including an incomplete file, resulting in compile errors.

So i think your change will just introduce the previous behaviour, which i attempted to fix. That does not mean that the current rule is absolutely correct, maybe we should check the documentation of make again. IIRC, that scenario is mentioned somewhere there.

[mikrosk]

Actually @th-otto, you did break something there. When trying to reproduce scummvm/dockerized-bb#50 I could easily get the following (Ubuntu 22.04.2 LTS):

make[4]: Entering directory '/home/mikro/m68k-atari-mint-build/mintlib-master/syscall'
gcc -O -Wall -c check.c -o check.o
gcc -O -Wall -c generate.c -o generate.o
gcc -O -Wall -c main.c -o main.o
if bison --defines=pars.h.tmp$$ --output=pars.c pars.y; then mv pars.h.tmp$$ pars.h; else rm -f pars.h.tmp$$; exit 1; fi
gcc -O -Wall -c pars.c -o pars.o
pars.c:149:10: fatal error: pars.h.tmp19480: No such file or directory
  149 | #include "pars.h.tmp19480"
      |          ^~~~~~~~~~~~~~~~~
compilation terminated.
make[4]: *** [../checkrules:50: pars.o] Error 1
make[4]: Leaving directory '/home/mikro/m68k-atari-mint-build/mintlib-master/syscall'
make[3]: *** [Makefile:46: gen-syscall0] Error 2
make[3]: Leaving directory '/home/mikro/m68k-atari-mint-build/mintlib-master/syscall'
make[2]: *** [Makefile:162: all-recursive] Error 1
make[2]: Leaving directory '/home/mikro/m68k-atari-mint-build/mintlib-master'
make[1]: *** [Makefile:238: mintlib] Error 2
make[1]: Leaving directory '/home/mikro/m68k-atari-mint-build'

So I'd say it's the other way around, unless you fix it, we'll have to revert your patch. ;)

[th-otto]

Damn, ok, i'll have a look into that. Didn't realize that bison uses the --defines filename also to generate the include fro it,so that is definitely wrong now. Just wonder why it works her, and also in the build docker from github.

But the previous rule was also wrong. It only gives errors when running parallel makes, and isn't always reproducible, but it happens that pars.c is compiled before bison finishes writing pars.h. Maybe need a temp file here that is created when bison is finished, and add it as dependency for pars.o. Or do you have any better idea?

[th-otto]

I've pushed a fix now. Could please trigger a build of scummvm (without your patch) and see if it works now?

[mikrosk]

Confirmed, it seems fixed.