Omit utility doesn't respect methods on a type

[d-ellis]

🔎 Search Terms

Omit, Method

🕗 Version & Regression Information

• This is the behavior in every version I tried, and I reviewed the FAQ for entries about "Omit, Excludes, Methods" (And did a Ctrl+F search for "(): ")

⏯ Playground Link

https://www.typescriptlang.org/play/?ts=5.5.3#code/CYUwxgNghgTiAEkoGdnwCImQFxgewE8oAjCBAbwFgAoeO+ABwFdSBLMeUHfAkYALnjE8eMlAB2Abhr1GLCO05ZchABQBKQQDc8rYNOoBfGqCRxEecTngAhFCADC0VIKq164kAHd4GwZm5CEjIDWQZ8bDxsAgYQf2UeYJADQwMTcGhzJFR4ADEoMEiYAng3MPlFHChsRVAAM1ZPAB4nFGQHSwaAc3gQAA9sEHFgNAAlcDwYYCbuRq6AGngJAgA+FdVwqKiYuPhW1A7xbs1SmVkPb18T1QBJK2wJMBAAFR2m6Ni8Ott7feQV+AAMngAHkALasbAtZztTqsBbwADkYEs3CYhUmiJW6lC9FSNGM1BoKPu8AAMiAugUCHZkI4YfAALx5ApFAgAOnqjRAqjK9BJaIxMA0pXghnmZzoyDwYJAAAV8LEYNFBABGABMAGYJe4pTLHFAIBBiAUANaCEWMgHiJhGnWyaWygCyIGwAAs8MA-PAdHpTrrzgB6QMYPDwADK+vdc0lYoJOJoxIZTs9IBg4j+vQGQxG5Mp1Np9La-vKbA4eC0aZgegQjpALvdnu9vuAJfOdGDscJhiAA

💻 Code

declare class Destroyable {
    public destroyed: boolean;
    public destroy(): void;
}
declare const BaseClass: {
    new (): Destroyable;
    prototype: Destroyable;
};

declare class Factory {
    public static define<ClassConfig extends Record<string, any>>(prototype: ClassConfig): {
        new (): (InstanceType<typeof BaseClass> & Omit<ClassConfig, 'constructor'>);
    };
}

const LegacyBaseClass = Factory.define({
    constructor() { },
    someProperty: 123,
    someCallback: () => null,
    someMethod(): void {
        // Do Something
    }
});

class ModernClass extends LegacyBaseClass {
    public override someMethod(): void {
        //
    }
}

🙁 Actual behavior

ModernClass cannot override someMethod because of the following error
Class 'Destroyable & Omit<{ someProperty: number; someCallback: () => null; someMethod(): void; }, "constructor">' defines instance member property 'someMethod', but extended class 'ModernClass' defines it as instance member function.

🙂 Expected behavior

ModernClass should be able to add an override because someMethod is defined as a method not a property

Additional information about the issue

The issue is coming from the fact that Omit is not respecting the difference between methods and properties on the type passed into it.

type ClassConfig = {
    constructor(): any;
    someProperty: number;
    someCallback: () => null;
    someMethod(): void;
};

type RelevantConfig = Omit<ClassConfig, 'constructor'>;

// Expected
type RelevantConfig = {
    someProperty: number;
    someCallback: () => null;
    someMethod(): void;
};

// Actual
type RelevantConfig = {
    someProperty: number;
    someCallback: () => null;
    someMethod: () => void;
};

[jcalz]

Duplicate of #27689

[typescript-bot]

This issue has been marked as "Duplicate" and has seen no recent activity. It has been automatically closed for house-keeping purposes.