Re: PR30891: poor diagnostic with namespace in the function scope

[Mark Mitchell <mark at codesourcery dot com>]

Manuel López-Ibáñez wrote:

>> 2007-03-12  Manuel Lopez-Ibanez  <manu@gcc.gnu.org>
>>
>>   PR c++/30891
>>   * parser.c (cp_parser_statement): If 'namespace' is found, this only
>> can be a namespace alias definition, so parse it now.
>>   (cp_parser_namespace_alias_definition): if we find an open brace
>> instead of '=', then this is actually a misplaced namespace
>> definition.


> Index: gcc/cp/parser.c
> ===================================================================
> --- gcc/cp/parser.c	(revision 122755)
> +++ gcc/cp/parser.c	(working copy)
> @@ -6305,6 +6305,16 @@ cp_parser_statement (cp_parser* parser, 
>  	  statement = cp_parser_try_block (parser);
>  	  break;
>  
> +	case RID_NAMESPACE:
> +	  {
> +	    /* Try to parse the declaration-statement.  */
> +	    cp_parser_declaration_statement (parser);
> +	    /* If that worked, we are done.  */
> +	    if (!cp_parser_error_occurred (parser))
> +	      return;
> +	    goto restart;
> +	  }

Why the conditional return to restart?  Why not just
cp_parser_declaration_statement, followed by return?

> @@ -10845,6 +10855,15 @@ cp_parser_namespace_alias_definition (cp
>    if (identifier == error_mark_node)
>      return;
>    /* Look for the `=' token.  */
> +  if (cp_lexer_next_token_is (parser->lexer, CPP_OPEN_BRACE)) 
> +    {
> +      error ("%<namespace%> definition is not allowed here");
> +      /* Skip the definition.  */
> +      cp_lexer_consume_token (parser->lexer);
> +      cp_parser_skip_to_closing_brace (parser);
> +      cp_lexer_consume_token (parser->lexer);
> +      return;
> +    }

This kind of change of recovery should always be done under the guard of:

  if (!cp_parser_uncommitted_to_tentative_parse (parser))

since if this is a tentative parse, we want to abort the parse anyhow
because of the failure, so there's no point in skipping tokens, etc.

Thanks,

-- 
Mark Mitchell
CodeSourcery
mark@codesourcery.com
(650) 331-3385 x713