Microsoft/TypeScript

No report of implicit any type in a generator when destructuring

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#43,172 opened on Mar 10, 2021

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BugDomain: check: Type InferenceHelp Wanted

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Description

Bug Report

🔎 Search Terms

no implicit any, generator, yield, destructure #41348 - Report implicit any error for 'yield' result with no contextual type

🕗 Version & Regression Information

TypeScript 4.2.3

⏯ Playground Link

Playground link with relevant code

💻 Code

function* sample() {
    const a = yield 1 // error, as expected, a is implicitly any
    const { b } = yield 1 // no error, but expected, b is implicitly any
    const [c] = yield 1 // no error, but expected, c is implicitly any
}

🙁 Actual behavior

b, c implicitly have type any, but no error reported

🙂 Expected behavior

Errors reported

Contributor guide

Research direction
Trace the type checking logic for destructuring assignment in the context of yield expressions. Investigate how the compiler handles destructuring patterns (object and array) for the result of yield, and why it does not report implicit any errors in those cases. Compare with the simple assignment case where error is reported.
Tech stack
typescript
Domain
compilers
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
TypeScript
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65