From 57b30e8e226014c8d06bae0158e0c7fc679f700b Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Sun, 20 Feb 2000 21:32:16 +0000
Subject: Create a new expression node type RelabelType, which exists solely to
 represent the result of a binary-compatible type coercion.  At runtime it
 just evaluates its argument --- but during type resolution, exprType will
 pick up the output type of the RelabelType node instead of the type of the
 argument.  This solves some longstanding problems with dropped type
 coercions, an example being 'select now()::abstime::int4' which used to
 produce date-formatted output, not an integer, because the coercion to int4
 was dropped on the floor.

---
 src/backend/nodes/copyfuncs.c | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

(limited to 'src/backend/nodes/copyfuncs.c')

diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 5bf01e2272..fbef91b35d 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/nodes/copyfuncs.c,v 1.106 2000/02/15 20:49:09 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/nodes/copyfuncs.c,v 1.107 2000/02/20 21:32:05 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -873,6 +873,26 @@ _copySubLink(SubLink *from)
 	return newnode;
 }
 
+/* ----------------
+ *		_copyRelabelType
+ * ----------------
+ */
+static RelabelType *
+_copyRelabelType(RelabelType *from)
+{
+	RelabelType    *newnode = makeNode(RelabelType);
+
+	/* ----------------
+	 *	copy remainder of node
+	 * ----------------
+	 */
+	Node_Copy(from, newnode, arg);
+	newnode->resulttype = from->resulttype;
+	newnode->resulttypmod = from->resulttypmod;
+
+	return newnode;
+}
+
 /* ----------------
  *		_copyCaseExpr
  * ----------------
@@ -1617,6 +1637,9 @@ copyObject(void *from)
 		case T_SubLink:
 			retval = _copySubLink(from);
 			break;
+		case T_RelabelType:
+			retval = _copyRelabelType(from);
+			break;
 		case T_CaseExpr:
 			retval = _copyCaseExpr(from);
 			break;
-- 
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