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[nightly][regression] Wrong generic parameter inferred for constructed class instanceΒ #58158

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@MichaelMitchell-at

Description

@MichaelMitchell-at

πŸ”Ž Search Terms

generic, class, infer

πŸ•— Version & Regression Information

⏯ Playground Link

https://www.typescriptlang.org/play?ts=5.5.0-dev.20240411#code/KYDwDg9gTgLgBDAnmYcCCBnDBLA5gOwB4AVAGjgFUA+OAXjgHkBbbGE8ga2EQgDNKaAMkoBuAFBiAxgBsAhljgAxCBBI0A3mLja4kiPgwwoAV0kxoACjDGARtOySEALjjEAlHHUBfCTvRY8fAtjF3UQFwBGLzcXZVVMHAJ2T3C4KKoNLT8dPQN4ADcXBMDksMivGnoGGwArYDMAOnlEoO9yGAALbAwGmHJjN3FsnShgGGMofDh8YAB3JRULfMGs4YB6NbgAPQB+VeyN12RUAHI4wmKky6IyTzhUiJE4CvJ1e8iniqoTuG7piHgzUCsjsqHMCGOcDOKguASStzeD0+GRODX2fkOs1kMH2Ph8QA

πŸ’» Code

export type Assign<T, U> = Omit<T, keyof U> & U;

class Foo<T> {
    constructor(public t: T) {}

    assign(u: {x: 1}): Foo<Assign<T, {x: 1}>> {
        const v: Assign<T, {x: 1}> = Object.assign({}, this.t, u);
        return new Foo(v);
        // ^?
        // Type 'Foo<Assign<Assign<T, { x: 1; }>, { x: 1; }>>' is not assignable to type 'Foo<Assign<T, { x: 1; }>>'.
        // wat
    }
}

πŸ™ Actual behavior

Type error

πŸ™‚ Expected behavior

No type error

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