Microsoft/TypeScript

Type printing does not detect that a name is shadowed in the current scope

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#58,456 opened on May 7, 2024

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 (0 comments) (0 reactions) (0 assignees)TypeScript (6,726 forks)batch import
BugDomain: Declaration EmitHelp Wanted

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Description

🔎 Search Terms

global shadowed declarations

🕗 Version & Regression Information

  • This is the behavior in every version I tried, and I reviewed

⏯ Playground Link

Playground Link

💻 Code

// @strict: true
// @declaration: true
// @target: es2020

// @filename: a.ts
export const o = {[Symbol.iterator]: 1}

// @filename: b.ts

import { o } from "./a";
export class Symbol { }
export const g = o;

🙁 Actual behavior

The typeof of g is { [Symbol.iterator]: number; }. This leads to an incorrect declaration since Symbol is shadowed in the current scope

🙂 Expected behavior

The typeof of g is { [globalThis.Symbol.iterator]: number; }.

Additional information about the issue

No response

Contributor guide

Research direction
Investigate the type printer in checker.ts to understand how symbols are resolved when printing types, specifically for well known symbols like Symbol.iterator. Look for where the global Symbol reference is resolved and why it doesn't account for a local Symbol class in scope.
Tech stack
typescript
Domain
backendtooling
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.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
TypeScriptcompiler internals
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30