Fix ruleutils.c's dumping of whole-row Vars in ROW() and VALUES() contexts.

Normally ruleutils prints a whole-row Var as "foo.*".  We already knew that
that doesn't work at top level of a SELECT list, because the parser would
treat the "*" as a directive to expand the reference into separate columns,
not a whole-row Var.  However, Joshua Yanovski points out in bug #13776
that the same thing happens at top level of a ROW() construct; and some
nosing around in the parser shows that the same is true in VALUES().
Hence, apply the same workaround already devised for the SELECT-list case,
namely to add a forced cast to the appropriate rowtype in these cases.
(The alternative of just printing "foo" was rejected because it is
difficult to avoid ambiguity against plain columns named "foo".)

Back-patch to all supported branches.

1 files changed, 30 insertions, 5 deletions

diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index 6400fa0de3d..2942fc96d13 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -380,6 +380,8 @@ static void appendContextKeyword(deparse_context *context, const char *str,
 static void removeStringInfoSpaces(StringInfo str);
 static void get_rule_expr(Node *node, deparse_context *context,
 			  bool showimplicit);
+static void get_rule_expr_toplevel(Node *node, deparse_context *context,
+					   bool showimplicit);
 static void get_oper_expr(OpExpr *expr, deparse_context *context);
 static void get_func_expr(FuncExpr *expr, deparse_context *context,
 			  bool showimplicit);
@@ -4297,10 +4299,10 @@ get_values_def(List *values_lists, deparse_context *context)
 
 			/*
 			 * Strip any top-level nodes representing indirection assignments,
-			 * then print the result.
+			 * then print the result.  Whole-row Vars need special treatment.
 			 */
-			get_rule_expr(processIndirection(col, context, false),
-						  context, false);
+			get_rule_expr_toplevel(processIndirection(col, context, false),
+								   context, false);
 		}
 		appendStringInfoChar(buf, ')');
 	}
@@ -4691,7 +4693,8 @@ get_target_list(List *targetList, deparse_context *context,
 		 * the top level of a SELECT list it's not right (the parser will
 		 * expand that notation into multiple columns, yielding behavior
 		 * different from a whole-row Var).  We need to call get_variable
-		 * directly so that we can tell it to do the right thing.
+		 * directly so that we can tell it to do the right thing, and so that
+		 * we can get the attribute name which is the default AS label.
 		 */
 		if (tle->expr && IsA(tle->expr, Var))
 		{
@@ -7180,7 +7183,8 @@ get_rule_expr(Node *node, deparse_context *context,
 						!tupdesc->attrs[i]->attisdropped)
 					{
 						appendStringInfoString(buf, sep);
-						get_rule_expr(e, context, true);
+						/* Whole-row Vars need special treatment here */
+						get_rule_expr_toplevel(e, context, true);
 						sep = ", ";
 					}
 					i++;
@@ -7560,6 +7564,27 @@ get_rule_expr(Node *node, deparse_context *context,
 	}
 }
 
+/*
+ * get_rule_expr_toplevel		- Parse back a toplevel expression
+ *
+ * Same as get_rule_expr(), except that if the expr is just a Var, we pass
+ * istoplevel = true not false to get_variable().  This causes whole-row Vars
+ * to get printed with decoration that will prevent expansion of "*".
+ * We need to use this in contexts such as ROW() and VALUES(), where the
+ * parser would expand "foo.*" appearing at top level.  (In principle we'd
+ * use this in get_target_list() too, but that has additional worries about
+ * whether to print AS, so it needs to invoke get_variable() directly anyway.)
+ */
+static void
+get_rule_expr_toplevel(Node *node, deparse_context *context,
+					   bool showimplicit)
+{
+	if (node && IsA(node, Var))
+		(void) get_variable((Var *) node, 0, true, context);
+	else
+		get_rule_expr(node, context, showimplicit);
+}
+
 
 /*
  * get_oper_expr			- Parse back an OpExpr node