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tests/cases/conformance/types/union/discriminatedUnionTypes2.ts(27,30): error TS2322: Type '{ a: null; b: string; c: number; }' is not assignable to type '{ a: null; b: string; } | { a: string; c: number; }'.
Object literal may only specify known properties, and 'c' does not exist in type '{ a: null; b: string; }'.
tests/cases/conformance/types/union/discriminatedUnionTypes2.ts(32,11): error TS2339: Property 'b' does not exist on type '{ a: 0; b: string; } | { a: T; c: number; }'.
Property 'b' does not exist on type '{ a: T; c: number; }'.
==== tests/cases/conformance/types/union/discriminatedUnionTypes2.ts (2 errors) ====
function f10(x : { kind: false, a: string } | { kind: true, b: string } | { kind: string, c: string }) {
if (x.kind === false) {
x.a;
}
else if (x.kind === true) {
x.b;
}
else {
x.c;
}
}
function f11(x : { kind: false, a: string } | { kind: true, b: string } | { kind: string, c: string }) {
switch (x.kind) {
case false:
x.a;
break;
case true:
x.b;
break;
default:
x.c;
}
}
function f13(x: { a: null; b: string } | { a: string, c: number }) {
x = { a: null, b: "foo", c: 4}; // Error
~~~~
!!! error TS2322: Type '{ a: null; b: string; c: number; }' is not assignable to type '{ a: null; b: string; } | { a: string; c: number; }'.
!!! error TS2322: Object literal may only specify known properties, and 'c' does not exist in type '{ a: null; b: string; }'.
}
function f14<T>(x: { a: 0; b: string } | { a: T, c: number }) {
if (x.a === 0) {
x.b; // Error
~
!!! error TS2339: Property 'b' does not exist on type '{ a: 0; b: string; } | { a: T; c: number; }'.
!!! error TS2339: Property 'b' does not exist on type '{ a: T; c: number; }'.
}
}
type Result<T> = { error?: undefined, value: T } | { error: Error };
function f15(x: Result<number>) {
if (!x.error) {
x.value;
}
else {
x.error.message;
}
}
f15({ value: 10 });
f15({ error: new Error("boom") });
// Repro from #24193
interface WithError {
error: Error
data: null
}
interface WithoutError<Data> {
error: null
data: Data
}
type DataCarrier<Data> = WithError | WithoutError<Data>
function f20<Data>(carrier: DataCarrier<Data>) {
if (carrier.error === null) {
const error: null = carrier.error
const data: Data = carrier.data
} else {
const error: Error = carrier.error
const data: null = carrier.data
}
}
// Repro from #28935
type Foo = { tag: true, x: number } | { tag: false, y: number } | { [x: string]: string };
function f30(foo: Foo) {
if (foo.tag) {
foo;
}
else {
foo;
}
}
function f31(foo: Foo) {
if (foo.tag === true) {
foo;
}
else {
foo;
}
}
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