Function inference is incorrect with inline const objects

[Binek115]

🔎 Search Terms

inline inference, function return type, as const

🕗 Version & Regression Information

• This is the behavior in every version I tried, and I reviewed the FAQ

⏯ Playground Link

https://www.typescriptlang.org/play/?#code/MYewdgzgLgBAZmAjDAvDAFASlQPhgWQEMoALAOgCdCwATEAWyxjwAYYB+DAbxkIC4YAckSCYAX14QYoSFGwCeAIwGDFosQCgNM6PDAAmVBmwo8XDTGnhdIRQCsApsCgBBCAGFrsNOh78hIuKSVrKYFjAUDlAArhRgBMTkVLQMTKwcMLaOzm6esjAKMMpCauIA3BpiQA

💻 Code

const fn1 = () => Math.random() > 0 ? ({ a: '1' } as const) : { b: 'b' }

const fn2 = () => {
  const objectAsConst = ({ a: '1' } as const)
  return Math.random() > 0 ? objectAsConst : { b: 'b' };
}

🙁 Actual behavior

Return type for fn1 is

{
    readonly a: "1";
    b?: undefined;
} | {
    b: string;
    readonly a?: undefined;
}

while for fn2 is

{
    readonly a: "1";
} | {
    b: string;
}

🙂 Expected behavior

Return type for both functions should be

{
    readonly a: "1";
} | {
    b: string;
}

Inlining object should not change type of function

Additional information about the issue

No response

[jcalz]

Improved type inference for object literals is working as intended as implemented in #19513.

Also see #57563.

[typescript-bot]

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