Fix equalOwnProperties

s0 · s0 · commit 2c41d8b44e5a · 2018-08-30T14:08:24.000-07:00
equalOwnProperties would incorrectly report two map-like objects as equal in
the case where a property defined in `left` was not defined in `right` and
whose value was considered "equal" to undefined by the equalityComparer.

This bug was found by an alert on LGTM.com
diff --git a/src/compiler/core.ts b/src/compiler/core.ts
@@ -1272,7 +1272,7 @@ namespace ts {
         if (!left || !right) return false;
         for (const key in left) {
             if (hasOwnProperty.call(left, key)) {
-                if (!hasOwnProperty.call(right, key) === undefined) return false;
+                if (!hasOwnProperty.call(right, key)) return false;
                 if (!equalityComparer(left[key], right[key])) return false;
             }
         }

Original file line number	Diff line number	Diff line change
`@@ -1272,7 +1272,7 @@ namespace ts {`
`1272`	`1272`	`if (!left \|\| !right) return false;`
`1273`	`1273`	`for (const key in left) {`
`1274`	`1274`	`if (hasOwnProperty.call(left, key)) {`
`1275`		`- if (!hasOwnProperty.call(right, key) === undefined) return false;`
	`1275`	`+ if (!hasOwnProperty.call(right, key)) return false;`
`1276`	`1276`	`if (!equalityComparer(left[key], right[key])) return false;`
`1277`	`1277`	`}`
`1278`	`1278`	`}`