c++: structural_comptypes addition

[Nathan Sidwell]

I had to debug structural_comptypes, and its complex if conditions and 
tail calling of same_type_p made that hard.  I'd hope we can turn the 
eqivalent of return boolean_fn () ? true : false; into a tail call of 
the boolean.  We also were not dealing with TYPEOF_TYPE.

            gcc/cp/
            * typeck.c (structural_comptypes): [DECLTYPE_TYPE] break
            apart complex if.
            [UNDERLYING_TYPE]: Use an if.
            [TYPEOF_TYPE]: New.
nathan
--
Nathan Sidwell
diff --git i/gcc/cp/typeck.c w/gcc/cp/typeck.c
index 589e014f855..adc088ce1d7 100644
--- i/gcc/cp/typeck.c
+++ w/gcc/cp/typeck.c
@@ -1452,19 +1452,25 @@ structural_comptypes (tree t1, tree t2, int strict)
 
     case DECLTYPE_TYPE:
       if (DECLTYPE_TYPE_ID_EXPR_OR_MEMBER_ACCESS_P (t1)
-          != DECLTYPE_TYPE_ID_EXPR_OR_MEMBER_ACCESS_P (t2)
-	  || (DECLTYPE_FOR_LAMBDA_CAPTURE (t1)
-	      != DECLTYPE_FOR_LAMBDA_CAPTURE (t2))
-	  || (DECLTYPE_FOR_LAMBDA_PROXY (t1)
-	      != DECLTYPE_FOR_LAMBDA_PROXY (t2))
-          || !cp_tree_equal (DECLTYPE_TYPE_EXPR (t1), 
-                             DECLTYPE_TYPE_EXPR (t2)))
+          != DECLTYPE_TYPE_ID_EXPR_OR_MEMBER_ACCESS_P (t2))
+	return false;
+      if (DECLTYPE_FOR_LAMBDA_CAPTURE (t1) != DECLTYPE_FOR_LAMBDA_CAPTURE (t2))
+	return false;
+      if (DECLTYPE_FOR_LAMBDA_PROXY (t1) != DECLTYPE_FOR_LAMBDA_PROXY (t2))
+	return false;
+      if (!cp_tree_equal (DECLTYPE_TYPE_EXPR (t1), DECLTYPE_TYPE_EXPR (t2)))
         return false;
       break;
 
     case UNDERLYING_TYPE:
-      return same_type_p (UNDERLYING_TYPE_TYPE (t1), 
-			  UNDERLYING_TYPE_TYPE (t2));
+      if (!same_type_p (UNDERLYING_TYPE_TYPE (t1), UNDERLYING_TYPE_TYPE (t2)))
+	return false;
+      break;
+
+    case TYPEOF_TYPE:
+      if (!cp_tree_equal (TYPEOF_TYPE_EXPR (t1), TYPEOF_TYPE_EXPR (t2)))
+	return false;
+      break;
 
     default:
       return false;