c228924543
* Index signatures contribute properties to unions
This means that in a union like this:
```ts
type T = { foo: number } | { [s: string]: string }
```
`foo` is now a property of `T` with type `number | string`. Previously
it was not.
Two points of interest:
1. A readonly index signature makes the resulting union property readonly.
2. A numeric index signature only contributes number-named properties.
Fixes #21141
* Correctly handle numeric and symbol property names
1. Symbol-named properties don't contribute to unions.
2. Number-named properties should use the numeric index signature type,
if present, and fall back to the string index signature type, not the
other way round.
28 lines
851 B
TypeScript
28 lines
851 B
TypeScript
// @target: esnext
|
|
// @strict: true
|
|
type Two = { foo: { bar: true }, baz: true } | { [s: string]: string };
|
|
declare var u: Two
|
|
u.foo = 'bye'
|
|
u.baz = 'hi'
|
|
type Three = { foo: number } | { [s: string]: string } | { [s: string]: boolean };
|
|
declare var v: Three
|
|
v.foo = false
|
|
type Missing = { foo: number, bar: true } | { [s: string]: string } | { foo: boolean }
|
|
declare var m: Missing
|
|
m.foo = 'hi'
|
|
m.bar
|
|
type RO = { foo: number } | { readonly [s: string]: string }
|
|
declare var ro: RO
|
|
ro.foo = 'not allowed'
|
|
type Num = { '0': string } | { [n: number]: number }
|
|
declare var num: Num
|
|
num[0] = 1
|
|
num['0'] = 'ok'
|
|
const sym = Symbol()
|
|
type Both = { s: number, '0': number, [sym]: boolean } | { [n: number]: number, [s: string]: string | number }
|
|
declare var both: Both
|
|
both['s'] = 'ok'
|
|
both[0] = 1
|
|
both[1] = 0 // not ok
|
|
both[0] = 'not ok'
|
|
both[sym] = 'not ok'
|