Fix incorrect strictness test for ArrayCoerceExpr expressions.

tglsfdc · tglsfdc · commit 1571bc0f0613 · 2019-02-20T13:36:55.000-05:00
The recursion in contain_nonstrict_functions_walker() was done wrong, causing the strictness check to be bypassed for a parse node that is the immediate input of an ArrayCoerceExpr node. This could allow, for example, incorrect decisions about whether a strict SQL function can be inlined. I didn't add a regression test, because (a) the bug is so narrow and (b) I couldn't think of a test case that wasn't dependent on a large number of other behaviors, to the point where it would likely soon rot to the point of not testing what it was intended to. I broke this in commit c12d570, so back-patch to v11. Discussion: https://postgr.es/m/27571.1550617881@sss.pgh.pa.us
diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c
@@ -1179,9 +1179,8 @@ contain_nonstrict_functions_walker(Node *node, void *context)
 		 * the per-element expression is; so we should ignore elemexpr and
 		 * recurse only into the arg.
 		 */
-		return expression_tree_walker((Node *) ((ArrayCoerceExpr *) node)->arg,
-									  contain_nonstrict_functions_walker,
-									  context);
+		return contain_nonstrict_functions_walker((Node *) ((ArrayCoerceExpr *) node)->arg,
+												  context);
 	}
 	if (IsA(node, CaseExpr))
 		return true;
