Create a new parsetree node type, TypeCast, so that transformation of

SQL cast constructs can be performed during expression transformation
instead of during parsing.  This allows constructs like x::numeric(9,2)
and x::int2::float8 to behave as one would expect.

src/include/nodes/parsenodes.h

@@ -6,7 +6,7 @@
  *
  * Copyright (c) 1994, Regents of the University of California
  *
- * $Id: parsenodes.h,v 1.94 2000/01/16 20:04:58 petere Exp $
+ * $Id: parsenodes.h,v 1.95 2000/01/17 00:14:48 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -868,6 +868,22 @@ typedef struct A_Const
 	TypeName   *typename;		/* typecast */
 } A_Const;
 
+/*
+ * TypeCast - a CAST expression
+ *
+ * NOTE: for mostly historical reasons, A_Const and ParamNo parsenodes contain
+ * room for a TypeName; we only generate a separate TypeCast node if the
+ * argument to be casted is neither of those kinds of nodes.  In theory either
+ * representation would work, but it is convenient (especially for A_Const)
+ * to have the target type immediately available.
+ */
+typedef struct TypeCast
+{
+	NodeTag		type;
+	Node	   *arg;			/* the expression being casted */
+	TypeName   *typename;		/* the target type */
+} TypeCast;
+
 /*
  * CaseExpr - a CASE expression
  */