Re: [PATCH] parse-datetime: avoid "%pure-parser" deprecation warning from Bison 3.4

[Bernhard Voelker]

Hi Bruno,

On 7/19/19 5:03 AM, Bruno Haible wrote:
>> +    parse-datetime: avoid "%pure-parser" deprecation warning from Bison 3.4
> 
> I've pushed your change.

thanks.

> However, I think it would be good for "make" to behave reasonably when bison
> is not found or too old.
> 
> Here's a proposed patch (untested so far):

I see 2 issues with this patch ...

> 2019-07-19  Bruno Haible  <address@hidden>
> 
>       parse-datetime: Require Bison 2.7 or newer.
>       * m4/parse-datetime.m4 (gl_PARSE_DATETIME): Set PARSE_DATETIME_BISON.
>       Code taken from gettext's intl.m4.
>       * modules/parse-datetime (Makefile.am): Use PARSE_DATETIME_BISON instead
>       of YACC.
> 
> diff --git a/m4/parse-datetime.m4 b/m4/parse-datetime.m4
> index 597a44c..dd5e643 100644
> --- a/m4/parse-datetime.m4
> +++ b/m4/parse-datetime.m4
> @@ -1,4 +1,4 @@
> -# parse-datetime.m4 serial 22
> +# parse-datetime.m4 serial 23
>  dnl Copyright (C) 2002-2006, 2008-2019 Free Software Foundation, Inc.
>  dnl This file is free software; the Free Software Foundation
>  dnl gives unlimited permission to copy and/or distribute it,
> @@ -26,6 +26,37 @@ AC_DEFUN([gl_C_COMPOUND_LITERALS],
>  
>  AC_DEFUN([gl_PARSE_DATETIME],
>  [
> +  dnl parse-datetime.c is generated from parse-datetime.y. It requires bison,
> +  dnl because parse-datetime.y uses bison specific features. It requires at
> +  dnl least bison-2.7 for %define api.pure.
> +  dnl bison is only needed for the maintainer (who touches parse-datetime.y).
> +  dnl But in order to avoid separate Makefiles or --enable-maintainer-mode,
> +  dnl we put the rule in general Makefile. Now, some people carelessly touch
> +  dnl the files or have a broken "make" program, hence the parse-datetime.c
> +  dnl rule will sometimes fire. To avoid an error, defines 
> PARSE_DATETIME_BISON
> +  dnl to ":" if it is not present or too old.
> +  AC_CHECK_PROGS([PARSE_DATETIME_BISON], [bison])
> +  if test -z "$PARSE_DATETIME_BISON"; then
> +    ac_verc_fail=yes
> +  else
> +    dnl Found it, now check the version.
> +    AC_MSG_CHECKING([version of bison])
> +changequote(<<,>>)dnl
> +    ac_prog_version=`$PARSE_DATETIME_BISON --version 2>&1 | sed -n 's/^.*GNU 
> Bison.* \([0-9]*\.[0-9.]*\).*$/\1/p'`
> +    case $ac_prog_version in
> +      '') ac_prog_version="v. ?.??, bad"; ac_verc_fail=yes;;
> +      2.[7-9]* | [3-9].*)

This would run into a little problem in quite far future ...... when GNU Bison
reaches version 10.x.  Maybe adjust to:

+      2.[7-9]* | [3-9].* | [1-9][0-9].*)

?

> +changequote([,])dnl
> +         ac_prog_version="$ac_prog_version, ok"; ac_verc_fail=no;;
> +      *) ac_prog_version="$ac_prog_version, bad"; ac_verc_fail=yes;;
> +    esac
> +    AC_MSG_RESULT([$ac_prog_version])
> +  fi
> +  if test $ac_verc_fail = yes; then
> +    PARSE_DATETIME_BISON=:
> +  fi
> +  AC_SUBST([PARSE_DATETIME_BISON])
> +
>    dnl Prerequisites of lib/parse-datetime.h.
>    AC_REQUIRE([AM_STDBOOL_H])
>    AC_REQUIRE([gl_TIMESPEC])
> diff --git a/modules/parse-datetime b/modules/parse-datetime
> index 692da25..d54dafd 100644
> --- a/modules/parse-datetime
> +++ b/modules/parse-datetime
> @@ -38,7 +38,7 @@ parse-datetime.c: parse-datetime.y
>                                     y.tab.c parse-datetime.c \
>                                     y.tab.h parse-datetime.h \
>                                     y.output parse-datetime.output \
> -                                   -- $(YACC) $(YFLAGS) $(AM_YFLAGS) && \
> +                                   -- $(PARSE_DATETIME_BISON) -y -d 
> $(YFLAGS) $(AM_YFLAGS) && \
>       sed -e 's|".*/parse-datetime.y"|"parse-datetime.y"|' \
>        < parse-datetime.c > parse-datetime.c-t && \
>       rm -f parse-datetime.c && \
> 

During generation of parse-datetime.c, I'm getting these 2 new warnings:

  /home/berny/coreutils/./lib/parse-datetime.y:568.1-7: warning: POSIX Yacc 
does not support %define [-Wyacc]
    568 | %define api.pure
        | ^~~~~~~
  /home/berny/coreutils/./lib/parse-datetime.y:573.1-7: warning: POSIX Yacc 
does not support %expect [-Wyacc]
    573 | %expect 31
        | ^~~~~~~

Thanks & have a nice day,
Berny