Microsoft/TypeScript

Deprecated should support contextual type with signature resolution

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#39,296 opened on Jun 27, 2020

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Effort: ModerateExperience EnhancementHelp Wanted

Description

TypeScript Version: 3.7.x-dev.201xxxxx

Search Terms:

Code

// A *self-contained* demonstration of the problem follows...
// Test this by running `tsc` on the command-line, rather than through another build tool such as Gulp, Webpack, etc.

declare function h(v: (a: string) => void)

declare function vv (): void
/** @deprecated */
declare function vv (v: string): void
declare function vv (v?: string): void

h([|vv|])

Expected behavior: vvs is deprecated. Actual behavior: nothing. Playground Link:

Related Issues:

Contributor guide

Tech stack
typescript
Domain
tooling
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.
mostly clear
Prerequisites
TypeScript basicsoverload signaturesJSDoc deprecated
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30
Research direction
Investigate the TypeScript compiler's handling of deprecated overloads in contextual type positions. Focus on the checker.ts file, particularly the function that resolves signatures for overloaded functions. Check how the @deprecated JSDoc tag is propagated when the function is passed as an argument with a contextual type. The relevant code is likely in the checkCallExpression or related areas.