Fix binary_oper_exact() so that the heuristic 'an unknown literal on

one side of a binary operator is probably supposed to be the same type
as the other operand' will be applied for domain types.  This worked
in 7.3 but was broken in 7.4 due to code rearrangements.  Mea culpa.

src/backend/parser/parse_oper.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_oper.c,v 1.75 2003/09/25 06:58:01 petere Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_oper.c,v 1.76 2003/10/06 20:09:47 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -386,24 +386,48 @@ oprfuncid(Operator op)
  * Check for an "exact" match to the specified operand types.
  *
  * If one operand is an unknown literal, assume it should be taken to be
- * the same type as the other operand for this purpose.
+ * the same type as the other operand for this purpose.  Also, consider
+ * the possibility that the other operand is a domain type that needs to
+ * be reduced to its base type to find an "exact" match.
  */
 static Oid
 binary_oper_exact(Oid arg1, Oid arg2,
 				  FuncCandidateList candidates)
 {
+	FuncCandidateList	cand;
+	bool		was_unknown = false;
+
 	/* Unspecified type for one of the arguments? then use the other */
 	if ((arg1 == UNKNOWNOID) && (arg2 != InvalidOid))
+	{
 		arg1 = arg2;
+		was_unknown = true;
+	}
 	else if ((arg2 == UNKNOWNOID) && (arg1 != InvalidOid))
+	{
 		arg2 = arg1;
+		was_unknown = true;
+	}
 
-	while (candidates != NULL)
+	for (cand = candidates; cand != NULL; cand = cand->next)
 	{
-		if (arg1 == candidates->args[0] &&
-			arg2 == candidates->args[1])
-			return candidates->oid;
-		candidates = candidates->next;
+		if (arg1 == cand->args[0] && arg2 == cand->args[1])
+			return cand->oid;
+	}
+
+	if (was_unknown)
+	{
+		/* arg1 and arg2 are the same here, need only look at arg1 */
+		Oid		basetype = getBaseType(arg1);
+
+		if (basetype != arg1)
+		{
+			for (cand = candidates; cand != NULL; cand = cand->next)
+			{
+				if (basetype == cand->args[0] && basetype == cand->args[1])
+					return cand->oid;
+			}
+		}
 	}
 
 	return InvalidOid;