Re: AC_PROG_YACC: use bison -o y.tab.c

[Akim Demaille]

Ping!

Le 4 mars 2013 à 18:48, Akim Demaille <address@hidden> a écrit :

> Hi Autofolks,
> 
> The fact that Autoconf sets YACC to bison --yacc is troublesome,
> as it emasculates the Bison down to a Yacc-calf (I wouldn't like
> to be the vet performing the bollocksectomy of a Bison).
> 
> The appended patch addresses this concern by taking profit from
> the following behavior.

> Le 25 févr. 2013 à 14:26, Akim Demaille <address@hidden> a écrit :
> 
>> Actually I just found what could arguable called a bug in
>> Bison:
>> 
>>> $ ls f.y
>>> f.y
>>> $ bison -o y.tab.c -d -v f.y
>>> $ ls y.*
>>> y.output    y.tab.c         y.tab.h
>> 
>> where I would have expected "y.tab.output".  Fortunately this
>> is also what Automake/Autoconf expect.  So, if instead of -y
>> Autoconf were using '-o y.tab.c', everybody would be happy.
>> 
>> And then --yacc = '-Werror=yacc -o y.tab.c'.  I'd be happy
>> to avoid making --fixed-output-file public again, it's
>> useless.
> 
> (BTW, shouldn't the help notices such as the one for YACC
> be converted to '' instead of `'?).
> 
> commit 63683577534eba689d05c0f4e392379c53e57549
> Author: Akim Demaille <address@hidden>
> Date:   Mon Mar 4 18:35:13 2013 +0100
> 
>    AC_PROG_YACC: don't force Bison to warn against its own features
> 
>    When invoked with -y/--yacc, Bison warns when its extensions over
>    POSIX Yacc are used.  Yet many packages requiring GNU Bison use
>    Autoconf/Automake's Yacc support, which passes -y to Bison.  It turns
>    out that passing '-o y.tab.c' has exactly the desired effect:
>    generating not only y.tab.c but also y.tab.h with -d and y.output with -v.
> 
>    See http://lists.gnu.org/archive/html/bison-patches/2013-02/msg00100.html.
> 
>    * lib/autoconf/programs.m4 (AC_PROG_YACC): Use bison -o y.tab.c.
>    * NEWS, doc/autoconf.texi: Document this change.
> 
> diff --git a/NEWS b/NEWS
> index 1780cb9..a429c7b 100644
> --- a/NEWS
> +++ b/NEWS
> @@ -33,6 +33,11 @@ GNU Autoconf NEWS - User visible changes.
> - AC_PROG_CC_STDC, AC_PROG_CC_C89, AC_PROG_CC_C99 have been marked as 
> obsolete.
>   Applications should use AC_PROG_CC.
> 
> +- AC_PROG_YACC now uses 'bison -o y.tab.c' instead of 'bison -y'.  Both
> +  properly generate 'y.tab.c' and possibly 'y.tab.h' and 'y.output', but
> +  the latter also enable warnings for Bison extensions.  Add -Wyacc to
> +  your YFLAGS to enable them.
> +
> - AC_USE_SYSTEM_EXTENSIONS now enables more system extensions on HP-UX,
>   MINIX 3, and OS X.
> 
> diff --git a/doc/autoconf.texi b/doc/autoconf.texi
> index bf4823d..ad22fc6 100644
> --- a/doc/autoconf.texi
> +++ b/doc/autoconf.texi
> @@ -4219,7 +4219,7 @@ and is cached in the @code{ac_cv_path_SED} variable.
> @ovindex YACC
> @caindex prog_YACC
> If @code{bison} is found, set output variable @code{YACC} to @samp{bison
> --y}.  Otherwise, if @code{byacc} is found, set @code{YACC} to
> +-o y.tab.c}.  Otherwise, if @code{byacc} is found, set @code{YACC} to
> @samp{byacc}.  Otherwise set @code{YACC} to @samp{yacc}.
> The result of this test can be influenced by setting the variable
> @code{YACC} or the cache variable @code{ac_cv_prog_YACC}.
> diff --git a/lib/autoconf/programs.m4 b/lib/autoconf/programs.m4
> index f7af8b5..2057e78 100644
> --- a/lib/autoconf/programs.m4
> +++ b/lib/autoconf/programs.m4
> @@ -892,10 +892,10 @@ AN_PROGRAM([yacc],  [AC_PROG_YACC])
> AN_PROGRAM([byacc], [AC_PROG_YACC])
> AN_PROGRAM([bison], [AC_PROG_YACC])
> AC_DEFUN([AC_PROG_YACC],
> -[AC_CHECK_PROGS(YACC, 'bison -y' byacc, yacc)dnl
> +[AC_CHECK_PROGS(YACC, 'bison -o y.tab.c' byacc, yacc)dnl
> AC_ARG_VAR(YACC,
> [The `Yet Another Compiler Compiler' implementation to use.  Defaults to
> -the first program found out of: `bison -y', `byacc', `yacc'.])dnl
> +the first program found out of: `bison -o y.tab.c', `byacc', `yacc'.])dnl
> AC_ARG_VAR(YFLAGS,
> [The list of arguments that will be passed by default to $YACC.  This script
> will default YFLAGS to the empty string to avoid a default value of `-d' given
> 
>