Re: [RFH / Patch] PR 51222

[Paolo Carlini <paolo dot carlini at oracle dot com>]

Hi,

On 05/02/2012 03:47 AM, Jason Merrill wrote:
> On 05/01/2012 08:14 PM, Paolo Carlini wrote:
> > > I think we need to handle FIELD_DECL, too.
> > Are there hopes that handling FIELD_DECL like FUNCTION_DECL and VAR_DECL
> > (besides the DECL_LANG_SPECIFIC check) would work?
> I would think so.
Ok, if we want it, I adjusted the code, see attached.
> > A data point I can give you, I put a gcc_assert (TREE_CODE (t) != 
> > FIELD_DECL) in the default case of the walk_template_parms_r switch, 
> > and it never triggers for the whole testsuite.
>
> With your patch, what happens if you have a member access like
>
> template <class T>
> struct A
> {
>   T t;
>   auto f(A a) -> decltype (sizeof (a.t)) { }
> };
>
> I would expect that to hit the FIELD_DECL case.
Well, not really. The first time walk_template_parms_r is called, t is a 
SIZEOF_EXPR which remains unhandled, the function returns NULL_TREE. The 
second time, t is a COMPONENT_REF, thus !TYPE_P (t) is true, TREE_TYPE 
is NULL, the function immediately returns error_mark_node and the 
iteration ends (with the correct result that the expression is 
instantiation-dependent).

Does it make sense?

Anyway, the attached appear to also pass the testsuite, I could test it 
more completely tomorrow. If the FIELD_DECL bits seem safe to have... ;)

Thanks,
Paolo.

Attachment: patch_51222_8
Description: Text document