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// @strictNullChecks: true
type Item = Item1 | Item2;
interface Base {
bar: boolean;
}
interface Item1 extends Base {
kind: "A";
foo: string | undefined;
baz: boolean;
qux: true;
}
interface Item2 extends Base {
kind: "B";
foo: string | undefined;
baz: boolean;
qux: false;
}
function goo1(x: Item) {
if (x.kind === "A" && x.foo !== undefined) {
x.foo.length;
}
}
function goo2(x: Item) {
if (x.foo !== undefined && x.kind === "A") {
x.foo.length; // Error, intervening discriminant guard
}
}
function foo1(x: Item) {
if (x.bar && x.foo !== undefined) {
x.foo.length;
}
}
function foo2(x: Item) {
if (x.foo !== undefined && x.bar) {
x.foo.length;
}
}
function foo3(x: Item) {
if (x.baz && x.foo !== undefined) {
x.foo.length;
}
}
function foo4(x: Item) {
if (x.foo !== undefined && x.baz) {
x.foo.length;
}
}
function foo5(x: Item) {
if (x.qux && x.foo !== undefined) {
x.foo.length;
}
}
function foo6(x: Item) {
if (x.foo !== undefined && x.qux) {
x.foo.length; // Error, intervening discriminant guard
}
}
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