Re: [bug-gawk] [PATCH] dependency for parallel make (bison)

[Andrew J. Schorr]

On Tue, Sep 12, 2017 at 10:41:28AM +0300, Petr Ovtchenkov wrote:
> Add dependency between command.c and awkgram.c to avoid
> parallel bison running. Bison produce y.tab.c, so if
> ones generated in parallel, collision may happens.
> ---
>  Makefile.am | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/Makefile.am b/Makefile.am
> index 8660c11..3fb88d3 100644
> --- a/Makefile.am
> +++ b/Makefile.am
> @@ -207,7 +207,7 @@ awkgram.c: awkgram.y
>       if cmp -s y.tab.h $*.h; then rm -f y.tab.h; else mv y.tab.h $*.h; fi; \
>       else :; fi
>  
> -command.c: command.y
> +command.c: command.y awkgram.c
>       $(YACC) -p zz $<
>       sed 's/parse error/syntax error/g' < y.tab.c | awk -f 
> "$(srcdir)"/bisonfix.awk command > $*.c && rm y.tab.c
>  

Good catch. If we are allowed to use the "-o" option to yacc (bison?), then this
rule might be a better fix:

command.c: command.y
        $(YACC) -o $@ -p zz $<
        sed 's/parse error/syntax error/g' < $@ > address@hidden && mv 
address@hidden $@

But I don't know whether it's safe to use "-o" on all of our platforms.  With
-o, we could eliminate the bisonfix.awk hack for awkgram.y as well, but that
rule is a bit messier because of the shenanigans with y.tab.h.

And if we knew that we were dealing with GNU sed, we could write:

command.c: command.y
        $(YACC) -o $@ -p zz $<
        sed -i 's/parse error/syntax error/g' $@

Regards,
Andy