Re: [PATCH] yysyntax_error: make it manage its own memory.

[Akim Demaille]

Le 10 sept. 2009 à 07:16, Joel E. Denny a écrit :

> I'd like to push this patch to master and branch-2.5.  I need it for  
> that
> lookahead correction implementation I spoke about recently, but I  
> think
> it's worthwhile on its own as well.  Any objections?  I haven't  
> looked at
> porting this to the other skeletons yet, but would there be any  
> objections
> there?
>
> > From d3334adb83a8b87cfa7528ab184d0dbbe7283858 Mon Sep 17 00:00:00  
> > 2001
> From: Joel E. Denny <address@hidden>
> Date: Mon, 7 Sep 2009 22:01:16 -0400
> Subject: [PATCH] yysyntax_error: make it manage its own memory.
>
> This improves readability, eliminates the need to invoke the
> function twice and thus repeat the lookahead collection, and
> prepares for future extensions that will make those repetitions
> more expensive and that will require additional memory
> management in yysyntax_error.
> * data/yacc.c (yysyntax_error): Add arguments for message
> buffer variables stored in the parser.  Instead of size, return
> status similar to yyparse status but indicating success of
> message creation.  Import memory management code from...
> (yyparse, yypush_parse): ... here.

Hi Joel,

I'm not sure I understand what's going on here.  The code is meant to  
be used with either alloca or malloc, and now that you moved  
everything in syntax_error, I fail to see how alloca could work as  
expected.  Reading the patch (not the resulting code), it really seems  
like you're possibly returning some pointer to a alloca'ed block of  
memory.

I can't see how alloca could be used if not the way Paul made it.