TypeScript/tests/cases/compiler/discriminantPropertyCheck.ts
2019-01-24 10:12:35 -08:00

178 lines
3 KiB
TypeScript

// @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
}
}
// Repro from #27493
enum Types { Str = 1, Num = 2 }
type Instance = StrType | NumType;
interface StrType {
type: Types.Str;
value: string;
length: number;
}
interface NumType {
type: Types.Num;
value: number;
}
function func2(inst: Instance) {
while (true) {
switch (inst.type) {
case Types.Str: {
inst.value.length;
break;
}
case Types.Num: {
inst.value.toExponential;
break;
}
}
}
}
// Repro from #29106
const f = (_a: string, _b: string): void => {};
interface A {
a?: string;
b?: string;
}
interface B {
a: string;
b: string;
}
type U = A | B;
const u: U = {} as any;
u.a && u.b && f(u.a, u.b);
u.b && u.a && f(u.a, u.b);
// Repro from #29012
type Additive = '+' | '-';
type Multiplicative = '*' | '/';
interface AdditiveObj {
key: Additive
}
interface MultiplicativeObj {
key: Multiplicative
}
type Obj = AdditiveObj | MultiplicativeObj
export function foo(obj: Obj) {
switch (obj.key) {
case '+': {
onlyPlus(obj.key);
return;
}
}
}
function onlyPlus(arg: '+') {
return arg;
}
// Repro from #29496
declare function never(value: never): never;
const enum BarEnum {
bar1 = 1,
bar2 = 2,
}
type UnionOfBar = TypeBar1 | TypeBar2;
type TypeBar1 = { type: BarEnum.bar1 };
type TypeBar2 = { type: BarEnum.bar2 };
function func3(value: Partial<UnionOfBar>) {
if (value.type !== undefined) {
switch (value.type) {
case BarEnum.bar1:
break;
case BarEnum.bar2:
break;
default:
never(value.type);
}
}
}