On 3/23/20 8:49 AM, Jason Merrill wrote:
> On 3/21/20 5:59 PM, Martin Sebor wrote:
>> +      /* Diagnose class/struct/union mismatches.  IS_DECLARATION is 
>> false
>> +     for alias definition.  */
>> +      bool decl_class = (is_declaration
>> +             && cp_parser_declares_only_class_p (parser));
>>         cp_parser_check_class_key (parser, key_loc, tag_type, type, 
>> false,
>>                    cp_parser_declares_only_class_p (parser));
> 
> Don't you need to use the new variable?
> 
> Don't your testcases exercise this?

Of course they do.  This was a leftover from an experiment after I put
the initial updated patch together.  On final review I decided to adjust
some comments and forgot to restore the original use of the variable.

>> +      /* When TYPE is the use of an implicit specialization of a 
>> previously
>> +     declared template set TYPE_DECL to the type of the primary template
>> +     for the specialization and look it up in CLASS2LOC below.  For uses
>> +     of explicit or partial specializations TYPE_DECL already points to
>> +     the declaration of the specialization.
>> +     IS_USE is clear so that the type of an implicit instantiation 
>> rather
>> +     than that of a partial specialization is determined.  */
>> +      type_decl = TREE_TYPE (type_decl);
>> +      if (TREE_CODE (type_decl) != TEMPLATE_DECL)
>> +    type_decl = TYPE_MAIN_DECL (type_decl);
> 
> The comment is no longer relevant to the code.  The remaining code also 
> seems like it would have no effect; we already know type_decl is 
> TYPE_MAIN_DECL (type).

I removed the block of code.

Martin

PS I would have preferred to resolve just the reported problem in this
patch and deal with the template specializations more fully (and with
aliases) in a followup.  As it is, it has grown bigger and more complex
than I'm comfortable with, especially with the template specializations,
harder for me to follow, and obviously a lot more time-consuming not
just to put together but also to review.  Although this revision handles
many more template specialization cases correctly, there still are other
(arguably corner) cases that it doesn't.  I suspect getting those right
might even require a design change, which I see as out of scope at this
time (not to mention my ability).