microsoft / microsoft/TypeScript

Abstract classes will still import the value for a computed property at runtime

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Bug Domain: JS Emit
Dominant language
Go
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Merged PRs (30d)
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Description

TypeScript Version: 3.7.0-dev.20190920

abstract class import computed property
abstract class computed property imports for runtime

Code
sharedSymbol.ts

export const sharedSymbol: unique symbol = Symbol();

AbstractClass.ts

import { sharedSymbol } from "./sharedSymbol";

abstract class AbstractClass {
    public abstract [sharedSymbol]: string;
}

Expected behavior:
sharedSymbol.js is not imported by AbstractClass.js
Actual behavior:
The symbol is imported by AbstractClass.js despite it's use being omitted due to it's abstract nature

Playground Link: Unavailable due to the bug being related to imported values.

Related Issues: No, I did not find any

Contributor guide

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First steps

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  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Reproduce the issue with sharedSymbol.ts and AbstractClass.ts, then inspect the emitted AbstractClass.js and the compiler path handling abstract computed properties. Add a regression test for the imported value and verify that the emitted JavaScript no longer imports sharedSymbol.js.

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
Mostly clear
Newbie friendliness
42/100

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