Re: [PATCH 06/11] build: include <config.h> from lib/yyerror.c

[Akim Demaille]

Le 23 janv. 2012 à 11:57, Jim Meyering a écrit :

> Hi Akim,
> 
> How about this?

Actually, for mhistorical reason, yyerror is really expected
to return an int (by default, which is the case here).  I guess
it dates back to the good ol' time o' C when not declaring
was fine, and meant int.

http://pubs.opengroup.org/onlinepubs/7908799/xcu/yacc.html

> The following functions appear only in the yacc library accessible through 
> the -l y operand to cc or c89; they can therefore be redefined by a portable 
> application:
> int main(void)
> This function will call yyparse() and exit with an unspecified value. Other 
> actions within this function are unspecified.
> int yyerror(const char *s
> This function will write the NUL-terminated argument to standard error, 
> followed by a newline character.




> I didn't find anyone using the return value, so rather than
> trying to preserve semantics for nonexistent callers, I opted
> to make this yyerror function return void as documented.

What do you mean by "as documented"?

> 
> Oh, wait!
> I do see one non-void use.  It's in data/glr.c:
> 
>  return yyerror (]b4_yyerror_args[YY_("syntax error: cannot back up")),     \
> 
> From the context, I'm not sure if that code is ever used:
> 
>    ------------------------------------------
>    # undef YYBACKUP
>    # define YYBACKUP(Token, Value)                                            
>   \
>      return yyerror (]b4_yyerror_args[YY_("syntax error: cannot back up")),   
>   \
>             yyerrok, yyerr

I don't see what you mean here: the return value is ignored by ','.

> Anyhow, with that I'm not so sure it's ok to s/int/void/.

I don't think it is.  But there is no semantics attached to that
int.  0 would do fine.

> * lib/yyerror.c (yyerror): Use fputs and fputc rather than fprintf
> with a mere "%s\n" format.  Also, change the return type to void.
> This avoids a problem reported by Thiru Ramakrishnan in
> http://lists.gnu.org/archive/html/help-bison/2011-11/msg00000.html
> ---
> lib/yyerror.c |    7 ++++---
> 1 files changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/lib/yyerror.c b/lib/yyerror.c
> index 5eb339f..5ac0438 100644
> --- a/lib/yyerror.c
> +++ b/lib/yyerror.c
> @@ -20,10 +20,11 @@
> #include <config.h>
> #include <stdio.h>
> 
> -int yyerror (char const *);
> +void yyerror (char const *);
> 
> -int
> +void
> yyerror (char const *message)
> {
> -  return fprintf (stderr, "%s\n", message);
> +  fputs (message, stderr);
> +  fputc ('\n', stderr);
> }

So you are engaging yourself gnulib will never #define these guys? :)
Actually, is main.c's setlocale's also protected from such dependencies?

> #include <config.h>
> 
> #if HAVE_LOCALE_H
> # include <locale.h>
> #endif
> #if ! HAVE_SETLOCALE
> # define setlocale(Category, Locale)
> #endif
> 
> int yyparse (void);
> 
> int
> main (void)
> {
>   setlocale (LC_ALL, "");
>   return yyparse ();
> }