Re: [C++] Return error_mark_node from cp_parser_constant_expression

[Jason Merrill <jason at redhat dot com>]

On 06/04/2012 04:12 PM, Florian Weimer wrote:
> > This doesn't make sense to me. parser->integral_constant_expression_p
> > should always be true at this point if you're moving the restore later
> > (which also seems unnecessary).
>
> I think parser->integral_constant_expression_p reflects the result of
> the cp_parser_assignment_expression() call earlier in this function.

parser->integral_constant_expression_p is set to indicate that the 
current context expects an integral constant expression; the call to 
cp_parser_assignment_expression will not affect that.

If the expression turns out not to be a valid constant expression, then 
we set parser->non_integral_constant_expression_p to true, but we don't 
touch parser->integral_constant_expression_p.  I think the condition you 
want is

if (parser->non_integral_constant_expression_p
    && !allow_non_constant_p)

Jason