microsoft / microsoft/TypeScript
`Readonly<unknown>` is assignable to type `object`
Open
Nobody has claimed this yet.
Needs Proposal
Suggestion
- Dominant language
- Go
- Stars
- 111k
- Forks
- 14.4k
- Avg merge
- 1d 19h
- Merged PRs (30d)
- 117
Description
Bug Report
🔎 Search Terms
Readonly, unknown, object
🕗 Version & Regression Information
4.4.0-beta, 4.3.5, 3.3.3
⏯ Playground Link
Playground link with relevant code
💻 Code
const a: unknown = 1;
const b = Object.freeze(a); // Readonly<unknown>
const c: object = b;
🙁 Actual behavior
The code compiles with no errors.
🙂 Expected behavior
The code fails to compile with error: Type 'Readonly<unknown>' is not assignable to type 'object'..
Since unknown is not assignable to object, one would expect Readonly<unknown> to still be not assignable to object.
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by reproducing the provided code in the linked TypeScript Playground and confirm how Object.freeze produces Readonly. Trace the type-checking path for assignability to object, then add or update a regression test for this example and verify that it reports the expected error.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- typescript
- Domain
- compilers
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Clearly specified
- Newbie friendliness
- 48/100