Re: Purity of yyerror etc.

[Paul Eggert]

> From: Akim Demaille <address@hidden>
> Date: 03 Nov 2002 17:50:15 +0100
> 
> There is one issue I'm not happy with: the syntax of %parse-param and
> %lex-param.  I would much prefer keeping { }, and maybe < > for
> relations with the language underneath (currenly only C), and " " for
> Bison string tokens.  So maybe something like:
> 
> %parse-param { ast_t *ast } {ast}
> 
> or
> 
> %parse-param <ast> { ast_t *ast }

I like the idea of using {}.  But how about this simpler syntax instead?

%parse-param { ast_t *ast }

The parameter declaration consists of the C code within {}.  At first,
Bison can support only C declarations of the usual form, where the
declared identifier comes at the end.  If we need to add support later
for full C syntax, we can; but I suspect we won't need to, since it's
always easy to rephrase C declarations to put the declared identifier
at the end.

This syntax avoids the need for duplicating the declared identifier
("ast" in this case), and it makes the %parse-param directive easier
to explain and read.