Microsoft/TypeScript

`--isolatedDeclarations` allows generator functions

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#58,334 opened on Apr 26, 2024

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BugDomain: flag: isolatedDeclarationsHelp Wanted

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Description

🔎 Search Terms

  • generator functions
  • isolated declartions
  • yield

🕗 Version & Regression Information

5.5.0-dev.20240426

⏯ Playground Link

https://www.typescriptlang.org/play/?isolatedDeclarations=true&ts=5.5.0-dev.20240426#code/KYDwDg9gTgLgBAMwK4DsDGMCWEUCo4CGAzgCYAUAlHAN4BQcDcAnpsADYlwBMA3PYy3acAzH0ZwowGEigo4ARloBfIA

💻 Code

export function* asd() {
    yield 2;
    yield 3;
    return 1
}

🙁 Actual behavior

This is allowed, the following code is emitted even though it requires inference:

export declare function asd(): Generator<2 | 3, number, unknown>;

🙂 Expected behavior

This is disallowed (probably all generator functions)

Additional information about the issue

cc @dragomirtitian

Contributor guide

Research direction
Inspect the ` isolatedDeclarations` check for generator functions in the TypeScript compiler. Trace the code path that emits declarations for generator functions and ensure that generator functions are flagged as requiring inference.
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.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
TypeScriptgenerators
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30