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Apparent properties in union of primitive and object causes incorrect error #31668
Description
TypeScript Version: 3.5.1
Search Terms: sub blink sup bold HTML Element String.prototype methods
Code
type sign = (payload: string | object) => void;
const sign: sign = (payload) => { console.log(payload)}
sign({ sub: null })Expected behavior: Ok
Actual behavior:
$ ./node_modules/.bin/tsc --version
Version 3.5.1
$ ./node_modules/.bin/tsc --lib es2015 --strict ./repro.ts
repro.ts:5:6 - error TS2326: Types of property 'sub' are incompatible.
Type 'null' is not assignable to type '(() => string) | undefined'.
5 sign({ sub: null })
~~~~~~~~~~~~~
Found 1 error.
$ ./node_modules/.bin/tsc --version
Version 3.6.0-dev.20190530
$ ./node_modules/.bin/tsc --lib es2015 --strict ./repro.ts
repro.ts:5:6 - error TS2326: Types of property 'sub' are incompatible.
Type 'null' is not assignable to type '(() => string) | undefined'.
5 sign({ sub: null })
~~~~~~~~~~~~~
Found 1 error.
Activity
[-][3.5.1 Regression] String.prototype methods confusion when string|object[/-][+]Apparent properties in union of primitive and object causes incorrect error[/+]RyanCavanaugh commentedon May 31, 2019
Wesley Wigham (@weswigham) reduced
Looks like the discriminating logic gets tripped up
weswigham commentedon May 31, 2019
Hm, I guess we probably shouldn't look at apparent types for discriminators when
objectis involved in the union (since we only want to discriminate against other real object types, not primitive apparent types).