Re: vector comparisons in C++

[Marc Glisse <marc dot glisse at inria dot fr>]

On Fri, 14 Sep 2012, Jason Merrill wrote:

> On 09/14/2012 09:59 AM, Marc Glisse wrote:
> > * build_vector_type: don't use an opaque vector for the return type of
> >    operator< (not sure what the point was of making it opaque?)
>
> I think the point was to allow conversion of the result to a different vector 
> type.

Ah, I see. I'll change it back to opaque and remove that use from the 
testcase. I noticed that for the fold patch, I am using once opaque and 
once not-opaque, I'll make them both opaque, although it probably doesn't 
matter once we are out of the front-end.

> Why do you want it not to be opaque?

I wanted to use decltype(x<x) to find an integer vector type of the same 
size as x, and then actually be able to use it. Being opaque, it refuses 
to be initialized (cp/decl.c:5550). Maybe decltype (and others?) could 
return non-opaque types?

> > +	      error_at (location, "comparing vectors with different "
> > +				  "element types");
>
> Let's print the vector types in these errors.

Type is %qT right? I see a number of %q#T but can't remember where the doc 
is. Well, I'll try both and see what happens.

Thanks,

--
Marc Glisse