Microsoft/TypeScript

Cannot access protected field but private field inside nested class

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#59,989 opened on Sep 17, 2024

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 (1 comment) (1 reaction) (0 assignees)TypeScript (6,726 forks)batch import
BugDomain: classesHelp Wanted

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Description

🔎 Search Terms

private, protected

🕗 Version & Regression Information

Version 5.6.2

⏯ Playground Link

https://www.typescriptlang.org/play/?#code/KYDwDg9gTgLgBAYwDYEMDOa4DEITgbwChC5S4woIZgFqATOGACwEs0BJNABUutuAYBeOAEYA3CTIUWANxTVGrDtyiz5wOMPHEycAEYooACgCUALhx4iu3QggA7NPGbzNithJtlJXqMBgArlD2cPbAAO6IqBhwoNT2dJiWBDpeNmgQALb+rPYA5qYpacVwfoHBivIAdMxsnDxqCgDUlTA1SvW8NPSeJaQAvj42g7qD-UA

💻 Code

export class Foo {

    protected thisIsProtected = 1;
    private thisIsPrivate = 1;

    bar():Foo {
        const that = this;
        
        return new class extends Foo {

            something() {
                return that.thisIsPrivate + that.thisIsProtected;
            }
        }
    }
}

🙁 Actual behavior

I get a compile error for that.thisIsProtected, but not for that.thisIsPrivate

🙂 Expected behavior

I can access the protected field, like the private

Additional information about the issue

No response

Contributor guide

Research direction
Inspect the TypeScript compiler's handling of protected member accessibility in nested classes, specifically why `that.thisIsProtected` is flagged as an error while `that.thisIsPrivate` is not. Look at the checker's logic for access checks on protected members when accessed through an alias (`that`).
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.
Fresh
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.
60