Re: [C++ Patch/RFC] PR 71169 ("[7/8 Regression] ICE on invalid C++ code in pop_nested_class"), PR 71832 and more

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

Hi,

On 07/03/2018 16:38, Jason Merrill wrote:
> On Tue, Mar 6, 2018 at 5:00 PM, Paolo Carlini <paolo.carlini@oracle.com> wrote:
> > On 06/03/2018 21:33, Jason Merrill wrote:
> > > Interesting, that seems like a promising idea.  I'm not sure we need
> > > to do this based on an error in a default template arg, though; can we
> > > drop
> > >
> > > +  || error_operand_p (TREE_PURPOSE (parameter)))
> > >
> > > ?
> > Good point, yes, I believe we can, isn't necessary for all the snippets I
> > have around neither apparently to pass the testsuite (but this is rather
> > straightforward, right?). As I said, I tried many different things, some
> > also fiddled with TREE_PURPOSE, in pt.c too, but in what I sent I only added
> > the check out of a reflex. Anyway, the below is in libstdc++, so far so
> > good.
> What if, instead of adding another flag to cp_parser, we look for
> errors in the template parms for a particular member before we do any
> late parsing for it?
Thus do the check before:

    FOR_EACH_VEC_SAFE_ELT (unparsed_funs_with_definitions, ix, decl)
      cp_parser_late_parsing_for_member (parser, decl);

and therefore skip the whole set of unparsed_funs? Because the template 
parameters to be considered is the same for all of them, right? 
(otherwise something is seriously wrong with my very idea!) And what 
about the other entities in the 'else if 
(--parser->num_classes_being_defined == 0)' body? On one hand I'm 
certainly concerned that we may be too heavy handed, on the other hand 
we may risk inconsistencies, with some definitions available during 
error recovery other not, where all of them have broken outer template 
parameters anyway. Well, in general, I must say that - assuming the 
possibly erroneous template parameters are shared by all the entities in 
the 'else if (--parser->num_classes_being_define == 0)' body - it would 
be too bad going through again all the template parameters where with 
just a bool we could save the work that we already did anyway, if see 
what I mean...

Paolo.