Revert previous patch.

From-SVN: r52166

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

@@ -3426,18 +3426,6 @@ 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);
@@ -5348,23 +5336,10 @@ lookup_tag (form, name, binding_level, thislevel_only)
 	    else
 	      old = BINDING_TYPE (old);
 
-	    /* 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 it has an original type, it is a typedef, and we
+	       should not return it.  */
 	    if (old && DECL_ORIGINAL_TYPE (TYPE_NAME (old)))
-	      {
-		old = DECL_ORIGINAL_TYPE (TYPE_NAME (old));
-		if (TYPE_IDENTIFIER (old) != name
-		    || context_for_name_lookup (TYPE_NAME (old)) != tail)
-		  old = NULL_TREE;
-	      }
+	      old = NULL_TREE;
 	    if (old && TREE_CODE (old) != form
 		&& (form == ENUMERAL_TYPE || TREE_CODE (old) == ENUMERAL_TYPE))
 	      {

gcc/testsuite/ChangeLog

-2002-04-11  Richard Sandiford  <rsandifo@redhat.com>
-
-	* g++.dg/ext/attrib5.C: New test.
-
 2002-04-10  Janis Johnson  <janis187@us.ibm.com>
 
 	* g77.f-torture/execute/6177.f: New test.

gcc/testsuite/g++.dg/ext/attrib5.C

-// There were two related problems here, depending on the vintage.  At
-// one time:
-//
-//    typedef struct A { ... } A __attribute__ ((aligned (16)));
-//
-// would cause original_types to go into an infinite loop.  At other
-// times, the attributes applied to an explicit typedef would be lost
-// (check_b2 would have a negative size).
-
-// First check that the declaration is accepted and has an effect.
-typedef struct A { int i; } A __attribute__ ((aligned (16)));
-int check_A[__alignof__ (A) >= 16 ? 1 : -1];
-
-// Check that the alignment is only applied to the typedef.
-struct B { int i; };
-namespace N { typedef B B; };
-typedef struct B B __attribute__((aligned (16)));
-N::B b1;
-B b2;
-int check_b1[__alignof__ (b1) == __alignof__ (int) ? 1 : -1];
-int check_b2[__alignof__ (b2) >= 16 ? 1 : -1];
-
-// The fix for this case involved a change to lookup_tag.  This 
-// bit just checks against a possible regression.
-namespace N { struct C; };
-typedef struct N::C C;		// { dg-error "previous declaration" }
-struct C;			// { dg-error "conflicting types" }