linux-kernel - Re: [PATCH v2] kbuild: support byacc as alternative YACC to bison

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Date:   Wed, 30 Oct 2019 11:58:59 +0900
From:   Masahiro Yamada <yamada.masahiro@...ionext.com>
To:     Ethan Sommer <e5ten.arch@...il.com>
Cc:     Michal Marek <michal.lkml@...kovi.net>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Sedat Dilek <sedat.dilek@...il.com>,
        Nathan Chancellor <natechancellor@...il.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        DTML <devicetree@...r.kernel.org>
Subject: Re: [PATCH v2] kbuild: support byacc as alternative YACC to bison

On Wed, Oct 30, 2019 at 12:02 AM Ethan Sommer <e5ten.arch@...il.com> wrote:
>
> Switches to a more portable set of flags for generating the same file
> names instead of the bison-specific --defines, uses the more portable -V
> instead of --version, and explicitly defines YYSTYPE in lex.l, which
> bison implicitly defines if not present but byacc does not.
>
> Add %locations to dtc-parser.y to explicitly enable location tracking
> for byacc, and define YYERROR_CALL explicitly to prevent the locations
> directive from causing it to be defined to a 2-parameter call to
> yyerror, which dtc-parser.y defines to accept one parameter.
>
> Requires byacc to be built with --enable-btyacc.
>
> Signed-off-by: Ethan Sommer <e5ten.arch@...il.com>
> ---
>  scripts/Makefile.host     | 2 +-
>  scripts/dtc/dtc-parser.y  | 4 ++++
>  scripts/genksyms/Makefile | 2 +-
>  scripts/genksyms/lex.l    | 2 ++
>  4 files changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/scripts/Makefile.host b/scripts/Makefile.host
> index 4c51c95d40f4..64e98e1d4825 100644
> --- a/scripts/Makefile.host
> +++ b/scripts/Makefile.host
> @@ -11,7 +11,7 @@ $(obj)/%.lex.c: $(src)/%.l FORCE
>  # YACC
>  # ---------------------------------------------------------------------------
>  quiet_cmd_bison = YACC    $(basename $@).[ch]
> -      cmd_bison = $(YACC) -o $(basename $@).c --defines=$(basename $@).h -t -l $<
> +      cmd_bison = $(YACC) -b $(basename $(basename $@)) -d -t -l $<


Hmm, this is unfortunate since there is no common way to
specify the header path directly.

I am not sure how much effort we should invent
to support non-GNU implementation
since we already rely on various GNU tools.

If we decide to support byacc,
we must carry the restriction
that bans GNU-extension.






>  $(obj)/%.tab.c $(obj)/%.tab.h: $(src)/%.y FORCE
>         $(call if_changed,bison)
> diff --git a/scripts/dtc/dtc-parser.y b/scripts/dtc/dtc-parser.y
> index 2ed4dc1f07fd..40dcf4f149da 100644
> --- a/scripts/dtc/dtc-parser.y
> +++ b/scripts/dtc/dtc-parser.y
> @@ -2,6 +2,8 @@
>  /*
>   * (C) Copyright David Gibson <dwg@....ibm.com>, IBM Corporation.  2005.
>   */
> +%locations
> +
>  %{
>  #include <stdio.h>
>  #include <inttypes.h>
> @@ -17,6 +19,8 @@ extern void yyerror(char const *s);
>                 treesource_error = true; \
>         } while (0)
>
> +#define YYERROR_CALL(msg) yyerror(msg)
> +
>  extern struct dt_info *parser_output;
>  extern bool treesource_error;
>  %}
> diff --git a/scripts/genksyms/Makefile b/scripts/genksyms/Makefile
> index 78629f515e78..397c2dc8182b 100644
> --- a/scripts/genksyms/Makefile
> +++ b/scripts/genksyms/Makefile
> @@ -15,7 +15,7 @@ genksyms-objs := genksyms.o parse.tab.o lex.lex.o
>  ifeq ($(findstring 1,$(KBUILD_EXTRA_WARN)),)
>
>  quiet_cmd_bison_no_warn = $(quiet_cmd_bison)
> -      cmd_bison_no_warn = $(YACC) --version >/dev/null; \
> +      cmd_bison_no_warn = $(YACC) -V >/dev/null; \
>                           $(cmd_bison) 2>/dev/null
>
>  $(obj)/pars%.tab.c $(obj)/pars%.tab.h: $(src)/pars%.y FORCE
> diff --git a/scripts/genksyms/lex.l b/scripts/genksyms/lex.l
> index e265c5d96861..0580c088527f 100644
> --- a/scripts/genksyms/lex.l
> +++ b/scripts/genksyms/lex.l
> @@ -19,6 +19,8 @@
>  #include "genksyms.h"
>  #include "parse.tab.h"
>
> +extern YYSTYPE yylval;
> +
>  /* We've got a two-level lexer here.  We let flex do basic tokenization
>     and then we categorize those basic tokens in the second stage.  */
>  #define YY_DECL                static int yylex1(void)
> --
> 2.23.0
>


--
Best Regards
Masahiro Yamada