Index: src/backend/parser/parse_expr.c
===================================================================
RCS file: /opt/src/cvs/pgsql-server/src/backend/parser/parse_expr.c,v
retrieving revision 1.160
diff -c -r1.160 parse_expr.c
*** src/backend/parser/parse_expr.c	4 Aug 2003 02:40:01 -0000	1.160
--- src/backend/parser/parse_expr.c	8 Aug 2003 21:53:25 -0000
***************
*** 45,51 ****
  static Node *transformColumnRef(ParseState *pstate, ColumnRef *cref);
  static Node *transformIndirection(ParseState *pstate, Node *basenode,
  					 List *indirection);
! 
  
  /*
   * Initialize for parsing a new query.
--- 44,50 ----
  static Node *transformColumnRef(ParseState *pstate, ColumnRef *cref);
  static Node *transformIndirection(ParseState *pstate, Node *basenode,
  					 List *indirection);
! static bool exprIsNullConstantTypeCast(Node *arg);
  
  /*
   * Initialize for parsing a new query.
***************
*** 394,421 ****
  							Node	   *lexpr = transformExpr(pstate,
  															  a->lexpr);
  
- 							ltype = exprType(lexpr);
- 							foreach(telem, (List *) a->rexpr)
- 							{
- 								rtype = LookupTypeName(lfirst(telem));
- 								matched = (rtype == ltype);
- 								if (matched)
- 									break;
- 							}
- 
- 							/*
- 							 * Expect two forms: equals or not equals.
- 							 * Flip the sense of the result for not
- 							 * equals.
- 							 */
- 							if (strcmp(strVal(lfirst(a->name)), "!=") == 0)
- 								matched = (!matched);
- 
  							n = makeNode(A_Const);
  							n->val.type = T_String;
- 							n->val.val.str = (matched ? "t" : "f");
  							n->typename = SystemTypeName("bool");
  
  							result = transformExpr(pstate, (Node *) n);
  						}
  						break;
--- 393,426 ----
  							Node	   *lexpr = transformExpr(pstate,
  															  a->lexpr);
  
  							n = makeNode(A_Const);
  							n->val.type = T_String;
  							n->typename = SystemTypeName("bool");
  
+ 							if (exprIsNullConstantTypeCast(a->lexpr))
+ 								n->val.val.str = "f";
+ 							else
+ 							{
+ 								ltype = exprType(lexpr);
+ 								foreach(telem, (List *) a->rexpr)
+ 								{
+ 									rtype = LookupTypeName(lfirst(telem));
+ 									matched = (rtype == ltype);
+ 									if (matched)
+ 										break;
+ 								}
+ 
+ 								/*
+ 								 * Expect two forms: equals or not equals.
+ 								 * Flip the sense of the result for not
+ 								 * equals.
+ 								 */
+ 								if (strcmp(strVal(lfirst(a->name)), "!=") == 0)
+ 									matched = (!matched);
+ 
+ 								n->val.val.str = (matched ? "t" : "f");
+ 							}
+ 
  							result = transformExpr(pstate, (Node *) n);
  						}
  						break;
***************
*** 1567,1570 ****
--- 1572,1588 ----
  						format_type_be(targetType))));
  
  	return expr;
+ }
+ 
+ 
+ /* exprIsNullConstantTypeCast()
+  * Recursively test whether an a_expr is a typecast NULL constant or not.
+  */
+ static bool
+ exprIsNullConstantTypeCast(Node *arg)
+ {
+ 	if (arg && IsA(arg, TypeCast))
+ 		return exprIsNullConstantTypeCast(((TypeCast *) arg)->arg);
+ 
+ 	return exprIsNullConstant(arg);
  }