Prevent failure when RowExpr or XmlExpr is parse-analyzed twice.

transformExpr() is required to cope with already-transformed expression
trees, for various ugly-but-not-quite-worth-cleaning-up reasons.  However,
some of its newer subroutines hadn't gotten the memo.  This accounts for
bug #7763 from Norbert Buchmuller: transformRowExpr() was overwriting the
previously determined type of a RowExpr during CREATE TABLE LIKE INCLUDING
INDEXES.  Additional investigation showed that transformXmlExpr had the
same kind of problem, but all the other cases seem to be safe.

Andres Freund and Tom Lane

diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 2b992fab4a7d06e5f2d9ba659a8b29520ab970bd..eb75f37e47c5aac8bc69c43302b9a4d925a9720e 100644 (file)
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -9817,6 +9817,9 @@ makeXmlExpr(XmlExprOp op, char *name, List *named_args, List *args)
    x->named_args = named_args;
    x->arg_names = NIL;
    x->args = args;
+   /* xmloption, if relevant, must be filled in by caller */
+   /* type and typmod will be filled in during parse analysis */
+   x->type = InvalidOid;           /* marks the node as not analyzed */
    return (Node *) x;
 }
 

diff --git a/src/backend/parser/parse_expr.c b/src/backend/parser/parse_expr.c
index 98b8572464841561b63a5dcd16d073c27fa1185b..c27a1373be0ab770d8d9fff204c4e28f02299d3a 100644 (file)
--- a/src/backend/parser/parse_expr.c
+++ b/src/backend/parser/parse_expr.c
@@ -92,6 +92,8 @@ static Expr *make_distinct_op(ParseState *pstate, List *opname,
  * function argument to the required type (via coerce_type())
  * can apply transformExpr to an already-transformed subexpression.
  * An example here is "SELECT count(*) + 1.0 FROM table".
+ * 3. CREATE TABLE t1 (LIKE t2 INCLUDING INDEXES) can pass in
+ * already-transformed index expressions.
  * While it might be possible to eliminate these cases, the path of
  * least resistance so far has been to ensure that transformExpr() does
  * no damage if applied to an already-transformed tree.  This is pretty
@@ -1341,7 +1343,13 @@ transformArrayExpr(ParseState *pstate, ArrayExpr *a)
 static Node *
 transformRowExpr(ParseState *pstate, RowExpr *r)
 {
-   RowExpr    *newr = makeNode(RowExpr);
+   RowExpr    *newr;
+
+   /* If we already transformed this node, do nothing */
+   if (OidIsValid(r->row_typeid))
+       return (Node *) r;
+
+   newr = makeNode(RowExpr);
 
    /* Transform the field expressions */
    newr->args = transformExpressionList(pstate, r->args);
@@ -1431,15 +1439,22 @@ transformMinMaxExpr(ParseState *pstate, MinMaxExpr *m)
 static Node *
 transformXmlExpr(ParseState *pstate, XmlExpr *x)
 {
-   XmlExpr    *newx = makeNode(XmlExpr);
+   XmlExpr    *newx;
    ListCell   *lc;
    int         i;
 
+   /* If we already transformed this node, do nothing */
+   if (OidIsValid(x->type))
+       return (Node *) x;
+
+   newx = makeNode(XmlExpr);
    newx->op = x->op;
    if (x->name)
        newx->name = map_sql_identifier_to_xml_name(x->name, false, false);
    else
        newx->name = NULL;
+   newx->type = XMLOID;        /* this just marks the node as transformed */
+   newx->typmod = -1;
 
    /*
     * gram.y built the named args as a list of ResTarget.  Transform each,