Type inference with reduce functions

[falsandtru]

Type of array elements shouldn't affect type inference in this case.

TypeScript Version: 3.7.x-dev.20200115

Search Terms:

Code

([] as any[]).reduce(() => 0, 0); // any
([] as unknown[]).reduce(() => 0, 0); // unknown
([] as never[]).reduce(() => 0, 0); // number

Expected behavior:

([] as any[]).reduce(() => 0, 0); // number
([] as unknown[]).reduce(() => 0, 0); // number
([] as never[]).reduce(() => 0, 0); // never or number

Actual behavior:

([] as any[]).reduce(() => 0, 0); // any
([] as unknown[]).reduce(() => 0, 0); // unknown
([] as never[]).reduce(() => 0, 0); // number

Playground Link: https://www.typescriptlang.org/play/?target=99&ts=3.8.0-dev.20200115&ssl=1&ssc=1&pln=3&pc=46#code/BQbQugBAhgztB2BPcBKAdAJwKYBMCuAxlsMChALwB8EADADS0oDcEA9KwogFCiSwR54Aa3gB7AO7xUmXIWKkK1eoxbsBwsZJ7hoceFgBuWDNOz4iJMlVoMazNh3h4AtgCNjQA

Related Issues: #25454

[RyanCavanaugh]

Please add to our suite at #36554