Re: Last part of verify_type_vairant checks

[Eric Botcazou <ebotcazou at adacore dot com>]

>  - Ada builds !TYPE_ARTIFICIAL variant of TYPE_ARTIFICIAL type.
>    Eric, I can not really make sense of this. Is this expected?
>    If we have artificial type, how it can become not?

Yes, that's a bit unexpected and probably comes from the case where we build a 
variant and it's not really appropriate to do so (gnat_pushdecl):

	  /* ??? Copy and original type are not supposed to be variant but we
	     really need a variant for the placeholder machinery to work.  */
	  if (TYPE_IS_FAT_POINTER_P (t))
	    tt = build_variant_type_copy (t);
	  else
	    {
	      /* TYPE_NEXT_PTR_TO is a chain of main variants.  */
	      tt = build_distinct_type_copy (TYPE_MAIN_VARIANT (t));
	      if (TREE_CODE (t) == POINTER_TYPE)
		TYPE_NEXT_PTR_TO (TYPE_MAIN_VARIANT (t)) = tt;
	      tt = build_qualified_type (tt, TYPE_QUALS (t));
	    }

On the other hand, if the type declared in the source code is volatile, one 
could imagine that the non-volatile main variant be TYPE_ARTIFICIAL and the 
declared type be !TYPE_ARTIFICIAL.

>  - During Ada builds there are types that differ in TYPE_SIZES_GIMPLIFIED.
>    This is probably harmless but I am not sure it ishappen to happen.

That it's harmless I'm sure, otherwise it would already have bitten us. :-)
But I agree that it would be better to always gimplify the main variant first 
and propagate to the other variants, as done in gimplify_type_sizes.

If you have a patchlet for this one, you can open a PR and attach it.

-- 
Eric Botcazou