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.

diff --git a/gcc/cp/decl2.cc b/gcc/cp/decl2.cc
index 9e135af41b340ef51bd529117300c4b5367b1b0b..8ec9740c8a9e2168e22e70d9cc6b5518ca14edad 100644 (file)
--- a/gcc/cp/decl2.cc
+++ b/gcc/cp/decl2.cc
@@ -1468,7 +1468,8 @@ is_late_template_attribute (tree attr, tree decl)
 {
   tree name = get_attribute_name (attr);
   tree args = TREE_VALUE (attr);
-  const struct attribute_spec *spec = lookup_attribute_spec (name);
+  const struct attribute_spec *spec
+    = lookup_attribute_spec (TREE_PURPOSE (attr));
   tree arg;
 
   if (!spec)
@@ -1512,7 +1513,9 @@ is_late_template_attribute (tree attr, tree decl)
         second and following arguments.  Attributes like mode, format,
         cleanup and several target specific attributes aren't late
         just because they have an IDENTIFIER_NODE as first argument.  */
-      if (arg == args && attribute_takes_identifier_p (name)
+      if (arg == args
+         && get_attribute_namespace (attr) == gnu_identifier
+         && attribute_takes_identifier_p (name)
          && identifier_p (t))
        continue;
 

diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 7a019d33bda1d335830892dba59e0f20850d5cc9..8498730b6e430d1045e00366ab0be18fee3991cf 100644 (file)
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -12386,7 +12386,8 @@ tsubst_attribute (tree t, tree *decl_p, tree args,
      pass it through tsubst.  Attributes like mode, format,
      cleanup and several target specific attributes expect it
      unmodified.  */
-  else if (attribute_takes_identifier_p (get_attribute_name (t)))
+  else if (get_attribute_namespace (t) == gnu_identifier
+          && attribute_takes_identifier_p (get_attribute_name (t)))
     {
       tree chain
        = tsubst_expr (TREE_CHAIN (val), args, complain, in_decl);