c++: is_late_template_attribute and tsubst_attribute fixes

This has been discussed in the 1/9 Reflection thread, but doesn't depend on
reglection in any way.
cp_parser_std_attribute calls lookup_attribute_spec as:
    const attribute_spec *as
      = lookup_attribute_spec (TREE_PURPOSE (attribute));
so with TREE_LIST where TREE_VALUE is attribute name and TREE_PURPOSE
attribute ns.  Similarly c_parser_std_attribute.  And for
attribute_takes_identifier_p those do:
    else if (attr_ns == gnu_identifier
             && attribute_takes_identifier_p (attr_id))
and
        bool takes_identifier
          = (ns != NULL_TREE
             && strcmp (IDENTIFIER_POINTER (ns), "gnu") == 0
             && attribute_takes_identifier_p (name));
when handling std attributes (for GNU attributes they just call those
with the IDENTIFIER_NODE name.
is_late_template_attribute and tsubst_attribute pass to these functions
just get_attribute_name though, so handle attributes in all namespaces
as GNU attributes only, which means that lookup_attribute_spec can
return NULL or find a different attribute if it is not from gnu:: or
say standard attribute mapped to gnu::, or attribute_takes_identifier_p
can return true even for attributes for which it shouldn't.

I thought about changing attribute_takes_identifier_p to take optionally
TREE_LIST, but that would mean handling it in the target hooks too and
they only care about GNU attributes right now, so given the above
parser.cc/c-parser.cc snippets, the following patch just follow
what they do.

2025-12-06  Jakub Jelinek  <jakub@redhat.com>

	* decl2.cc (is_late_template_attribute): Call lookup_attribute_spec
	on TREE_PURPOSE (attr) rather than name.  Only call
	attribute_takes_identifier_p if get_attribute_namespace (attr) is
	gnu_identifier.
	* pt.cc (tsubst_attribute): Only call attribute_takes_identifier_p
	if get_attribute_namespace (t) is gnu_identifier.

0 files changed, 0 insertions, 0 deletions