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.

1 files changed, 24 insertions, 1 deletions

diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 5bf01e22722..fbef91b35d8 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 $
  *
  *-------------------------------------------------------------------------
  */
@@ -874,6 +874,26 @@ _copySubLink(SubLink *from)
 }
 
 /* ----------------
+ *		_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;