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Class properties cannot be initialized within constructor if the property key comes from a static class property (e.g. [Symbol.iterator]) #53626

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Open
Class properties cannot be initialized within constructor if the property key comes from a static class property (e.g. [Symbol.iterator])#53626
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rbuckton
Labels
Needs InvestigationThis issue needs a team member to investigate its status.RescheduledThis issue was previously scheduled to an earlier milestone
Milestone
TypeScript 5.7.0

Description

@quassnoi
Alex Bolenok (quassnoi)
opened on Apr 2, 2023

Bug Report

🔎 Search Terms

symbol property constructor 2564

🕗 Version & Regression Information

  • This changed between versions 4.6.4 and 4.7.4

⏯ Playground Link

Playground link with relevant code

💻 Code

const standaloneSymbol = Symbol("standalone");

class SymbolClass {
    static readonly staticSymbol = Symbol("static");
}

interface IHaveSymbols {
    [standaloneSymbol]: number;
    [SymbolClass.staticSymbol]: number;
}

class HavePropertyInitializedSymbols implements IHaveSymbols {
    [standaloneSymbol] = 1;
    [SymbolClass.staticSymbol] = 2;
}

class HaveOverriddenSymbols extends HavePropertyInitializedSymbols {
    constructor() {
        super();
        this[standaloneSymbol] = 3;
        this[SymbolClass.staticSymbol] = 4;
    }
}

class HaveConstructorInitializedSymbols implements IHaveSymbols {
    [standaloneSymbol]: number;
    [SymbolClass.staticSymbol]: number;
    constructor() {
        this[standaloneSymbol] = 3;
        this[SymbolClass.staticSymbol] = 4;
    }
}

🙁 Actual behavior

Property '[SymbolClass.staticSymbol]' has no initializer and is not definitely assigned in the constructor.(2564)
(property) SymbolClass.staticSymbol: typeof SymbolClass.staticSymbol

It's wrong because the property is definitely assigned in the constructor

🙂 Expected behavior

No error, because the property is definitely assigned in the constructor

Activity

  1. Alex Bolenok (quassnoi)
    changed the title [-]Symbol-keyed properties cannot be initialized within constructor if the symbol name comes from a static property (e.g. [Symbol.iterator])[/-] [+]Symbol-keyed properties cannot be initialized within constructor if the symbol key value comes from a static property (e.g. [Symbol.iterator])[/+] on Apr 2, 2023

  2. whzx5byb commented on Apr 2, 2023

    @whzx5byb
    whzx5byb
    on Apr 2, 2023

    Similar to #49594.

  3. quassnoi commented on Apr 3, 2023

    @quassnoi
    Alex Bolenok (quassnoi)
    on Apr 3, 2023
    Author

    String-keyed properties don't work either: https://www.typescriptlang.org/play?ts=5.1.0-dev.20230401#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-jmM8gnkRNHnOnhRpouXpMR28F+bpx8lvcoomJW1a7tatoNgaRpIAAosqsK2ICrgAHLwAirYYu2sLwoiyLlL2baHusuJvoO3SbrcK76NGv5xhiS5UWsARnu+Ki0JRo4yOu2wcUsW6WDuloQW6xHXhG84XjAmZZi+P6TlJT6ySe87-tJV7Ht+HJrrGC6SPySmlhwQA

  4. Alex Bolenok (quassnoi)
    changed the title [-]Symbol-keyed properties cannot be initialized within constructor if the symbol key value comes from a static property (e.g. [Symbol.iterator])[/-] [+]Class properties cannot be initialized within constructor if the property key comes from a static class property (e.g. [Symbol.iterator])[/+] on Apr 3, 2023
  5. Ryan Cavanaugh (RyanCavanaugh)
    added
    Needs InvestigationThis issue needs a team member to investigate its status.
    on Apr 10, 2023
  6. Ryan Cavanaugh (RyanCavanaugh)
    assigned
    Ron Buckton (rbuckton)
    on Apr 10, 2023
  7. Ryan Cavanaugh (RyanCavanaugh)
    added this to the TypeScript 5.2.0 milestone on Apr 10, 2023
  8. Ryan Cavanaugh (RyanCavanaugh)
    modified the milestones: TypeScript 5.2.0, TypeScript 5.5.0 on Mar 4, 2024

  9. LoganDark commented on May 30, 2024

    @LoganDark
    LoganDark (LoganDark)
    on May 30, 2024

    Just ran into this issue, super annoying. Can't assign Symbol.iterator in the constructor.

  10. Ryan Cavanaugh (RyanCavanaugh)
    added
    RescheduledThis issue was previously scheduled to an earlier milestone
    on Jul 26, 2024
  11. Ryan Cavanaugh (RyanCavanaugh)
    modified the milestones: TypeScript 5.5.0, TypeScript 5.7.0 on Jul 26, 2024
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