decl.c (duplicate_decls): Don't try to unify an implicit typedef with an explicit one.

	* decl.c (duplicate_decls): Don't try to unify an implicit typedef
	with an explicit one.
	(lookup_tag): Extract the tag of an explicit typedef.

From-SVN: r52159

gcc/cp/ChangeLog

+2002-04-11  Richard Sandiford  <rsandifo@redhat.com>
+
+	* decl.c (duplicate_decls): Don't try to unify an implicit typedef
+	with an explicit one.
+	(lookup_tag): Extract the tag of an explicit typedef.
+
 2002-04-10  Nathan Sidwell  <nathan@codesourcery.com>
 
 	PR c++/5507

gcc/cp/decl.c

@@ -3426,6 +3426,18 @@ duplicate_decls (newdecl, olddecl)
 	}
     }
 
+  /* Do not merge an implicit typedef with an explicit one.  In:
+
+       class A;
+       ...
+       typedef class A A __attribute__ ((foo));
+
+     the attribute should apply only to the typedef.  */
+  if (TREE_CODE (olddecl) == TYPE_DECL
+      && (DECL_IMPLICIT_TYPEDEF_P (olddecl)
+	  || DECL_IMPLICIT_TYPEDEF_P (newdecl)))
+    return 0;
+
   /* If new decl is `static' and an `extern' was seen previously,
      warn about it.  */
   warn_extern_redeclared_static (newdecl, olddecl);
@@ -5336,10 +5348,23 @@ lookup_tag (form, name, binding_level, thislevel_only)
 	    else
 	      old = BINDING_TYPE (old);
 
-	    /* If it has an original type, it is a typedef, and we
-	       should not return it.  */
+	    /* If the declaration has an original type, it must a
+	       typedef.  When it is an explicit typedef of the form:
+
+		   typedef struct A A;
+
+	       the original type will be the tag that we want.
+	       We should not return any other kind of typedef.
+
+	       Detect the valid case by checking that the original
+	       type has the same name and context as the typedef.  */
 	    if (old && DECL_ORIGINAL_TYPE (TYPE_NAME (old)))
-	      old = NULL_TREE;
+	      {
+		old = DECL_ORIGINAL_TYPE (TYPE_NAME (old));
+		if (TYPE_IDENTIFIER (old) != name
+		    || context_for_name_lookup (TYPE_NAME (old)) != tail)
+		  old = NULL_TREE;
+	      }
 	    if (old && TREE_CODE (old) != form
 		&& (form == ENUMERAL_TYPE || TREE_CODE (old) == ENUMERAL_TYPE))
 	      {