[gcc r12-7473] tree: Fix up warn_deprecated_use [PR104627]

[gcc r12-7473] tree: Fix up warn_deprecated_use [PR104627]

[Jakub Jelinek]

https://gcc.gnu.org/g:49bc9c6c1ef9441c3db586882e1985da3be9cfa1

commit r12-7473-g49bc9c6c1ef9441c3db586882e1985da3be9cfa1
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Fri Mar 4 09:53:36 2022 +0100

    tree: Fix up warn_deprecated_use [PR104627]
    
    The r12-7287-g1b71bc7c8b18bd1b change improved the -Wdeprecated
    warning for C++, but regressed it for C, in particular in
    gcc.dg/deprecated.c testcase we now report a type that actually isn't
    deprecated as deprecated instead of the one that is deprecated.
    
    The following change tries to find the middle ground between what
    we used to do before and what r12-7287 change does.
    If TYPE_STUB_DECL (node) is non-NULL (that is what happens with
    those C tests), then it will do what it used to do before (just smarter,
    there is no need to lookup_attribute when it is called again a few lines
    below this), if it is NULL, it will try
    TYPE_STUB_DECL (TYPE_MAIN_VARIANT (node)) - what the deprecated-16.C
    test needs.
    
    2022-03-04  Jakub Jelinek  <jakub@redhat.com>
    
            PR c/104627
            * tree.cc (warn_deprecated_use): For types prefer to use node
            and only use TYPE_MAIN_VARIANT (node) if TYPE_STUB_DECL (node) is
            NULL.

Diff:
---
 gcc/tree.cc | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/gcc/tree.cc b/gcc/tree.cc
index 4522d90c4d9..d6f900c53b4 100644
--- a/gcc/tree.cc
+++ b/gcc/tree.cc
@@ -12047,8 +12047,11 @@ warn_deprecated_use (tree node, tree attr)
 	attr = DECL_ATTRIBUTES (node);
       else if (TYPE_P (node))
 	{
-	  tree decl = TYPE_STUB_DECL (TYPE_MAIN_VARIANT (node));
+	  tree decl = TYPE_STUB_DECL (node);
 	  if (decl)
+	    attr = TYPE_ATTRIBUTES (TREE_TYPE (decl));
+	  else if ((decl = TYPE_STUB_DECL (TYPE_MAIN_VARIANT (node)))
+		   != NULL_TREE)
 	    {
 	      node = TREE_TYPE (decl);
 	      attr = TYPE_ATTRIBUTES (node);