coerce_type() failed to guard against trying to convert a NULL

constant to a different type.  Not sure that this could happen in ordinary
parser usage, but it can in some new code I'm working on...

diff --git a/src/backend/parser/parse_coerce.c b/src/backend/parser/parse_coerce.c
index 026c66168ba18bc60da5cf3c10e5a2826c286edb..297337da4dcc766f09decc4fa31ea93778ea8909 100644 (file)
--- a/src/backend/parser/parse_coerce.c
+++ b/src/backend/parser/parse_coerce.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *   $Header: /cvsroot/pgsql/src/backend/parser/parse_coerce.c,v 2.22 1999/08/05 02:33:53 tgl Exp $
+ *   $Header: /cvsroot/pgsql/src/backend/parser/parse_coerce.c,v 2.23 1999/08/24 00:09:56 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -60,24 +60,24 @@ coerce_type(ParseState *pstate, Node *node, Oid inputTypeId, Oid targetTypeId,
         * whereas float-to-int type conversion will round to integer.
         */
        Const      *con = (Const *) node;
+       Const      *newcon = makeNode(Const);
        Type        targetType = typeidType(targetTypeId);
-       char       *val;
 
-       /* We know the source constant is really of type 'text' */
-       val = textout((text *) con->constvalue);
+       newcon->consttype = targetTypeId;
+       newcon->constlen = typeLen(targetType);
+       newcon->constbyval = typeByVal(targetType);
+       newcon->constisnull = con->constisnull;
+       newcon->constisset = false;
 
-       /* now make a new const node */
-       con = makeNode(Const);
-       con->consttype = targetTypeId;
-       con->constlen = typeLen(targetType);
-       con->constvalue = stringTypeDatum(targetType, val, atttypmod);
-       con->constisnull = false;
-       con->constbyval = typeByVal(targetType);
-       con->constisset = false;
-
-       pfree(val);
+       if (! con->constisnull)
+       {
+           /* We know the source constant is really of type 'text' */
+           char       *val = textout((text *) con->constvalue);
+           newcon->constvalue = stringTypeDatum(targetType, val, atttypmod);
+           pfree(val);
+       }
 
-       result = (Node *) con;
+       result = (Node *) newcon;
    }
    else
    {
@@ -105,7 +105,7 @@ coerce_type(ParseState *pstate, Node *node, Oid inputTypeId, Oid targetTypeId,
         * such as coercing text 'now' to datetime?  Need a way to
         * know whether type conversion function is cacheable...
         */
-       if (IsA(node, Const))
+       if (IsA(node, Const) && ! ((Const *) node)->constisnull)
        {
            Const      *con = (Const *) node;
            Oid         convertFuncid;
@@ -122,9 +122,9 @@ coerce_type(ParseState *pstate, Node *node, Oid inputTypeId, Oid targetTypeId,
            con = makeNode(Const);
            con->consttype = targetTypeId;
            con->constlen = typeLen(targetType);
+           con->constbyval = typeByVal(targetType);
            con->constvalue = val;
            con->constisnull = false;
-           con->constbyval = typeByVal(targetType);
            con->constisset = false;
 
            result = (Node *) con;