2006-07-06  Alexandre Oliva  <aoliva@redhat.com>

	PR c/27898
	* c-typeck.c (tagged_types_tu_compatible_p): Enable exact
	matches between anonymous union fields.

2006-08-18  Jakub Jelinek  <jakub@redhat.com>

	PR c/27898
	* gcc.dg/pr27898.c: New test.

--- gcc/testsuite/gcc.dg/pr27898.c.jj	2006-08-18 09:19:33.000000000 +0200
+++ gcc/testsuite/gcc.dg/pr27898.c	2006-08-18 09:19:27.000000000 +0200
@@ -0,0 +1,8 @@
+/* PR c/27898 */
+/* { dg-do compile } */
+/* { dg-options "--combine" } */
+/* { dg-additional-sources "pr27898.c" } */
+
+union u { struct { int i; }; };
+
+extern int foo (union u *);
--- gcc/c-typeck.c.jj	2006-08-17 09:55:11.000000000 +0200
+++ gcc/c-typeck.c	2006-08-18 09:14:15.000000000 +0200
@@ -1072,11 +1072,12 @@ tagged_types_tu_compatible_p (tree t1, t
 	  {
 	    int result;
 	    
-	    
-	    if (DECL_NAME (s1) == NULL
-	        || DECL_NAME (s1) != DECL_NAME (s2))
+	    if (DECL_NAME (s1) != DECL_NAME (s2))
 	      break;
 	    result = comptypes_internal (TREE_TYPE (s1), TREE_TYPE (s2));
+
+	    if (result != 1 && !DECL_NAME (s1))
+	      break;
 	    if (result == 0)
 	      {
 		tu->val = 0;
@@ -1103,28 +1104,31 @@ tagged_types_tu_compatible_p (tree t1, t
 	  {
 	    bool ok = false;
 
-	    if (DECL_NAME (s1) != NULL)
-	      for (s2 = TYPE_FIELDS (t2); s2; s2 = TREE_CHAIN (s2))
-		if (DECL_NAME (s1) == DECL_NAME (s2))
-		  {
-		    int result;
-		    result = comptypes_internal (TREE_TYPE (s1), TREE_TYPE (s2));
-		    if (result == 0)
-		      {
-			tu->val = 0;
-			return 0;
-		      }
-		    if (result == 2)
-		      needs_warning = true;
-
-		    if (TREE_CODE (s1) == FIELD_DECL
-			&& simple_cst_equal (DECL_FIELD_BIT_OFFSET (s1),
-					     DECL_FIELD_BIT_OFFSET (s2)) != 1)
-		      break;
+	    for (s2 = TYPE_FIELDS (t2); s2; s2 = TREE_CHAIN (s2))
+	      if (DECL_NAME (s1) == DECL_NAME (s2))
+		{
+		  int result;
+
+		  result = comptypes_internal (TREE_TYPE (s1), TREE_TYPE (s2));
 
-		    ok = true;
+		  if (result != 1 && !DECL_NAME (s1))
+		    continue;
+		  if (result == 0)
+		    {
+		      tu->val = 0;
+		      return 0;
+		    }
+		  if (result == 2)
+		    needs_warning = true;
+
+		  if (TREE_CODE (s1) == FIELD_DECL
+		      && simple_cst_equal (DECL_FIELD_BIT_OFFSET (s1),
+					   DECL_FIELD_BIT_OFFSET (s2)) != 1)
 		    break;
-		  }
+
+		  ok = true;
+		  break;
+		}
 	    if (!ok)
 	      {
 		tu->val = 0;