Getting a setter-only property is typed as the setter's parameter's type instead of undefined

🔎 Search Terms

setter only

🕗 Version & Regression Information

• This is the behavior in every version I tried, from 5.7.3 down to 3.3.3333

⏯ Playground Link

https://www.typescriptlang.org/play/?ts=5.7.3#code/MYewdgzgLgBANgQzAcwK4OQUxgXhgbwCgYYJNZhUAnKzMKACjAQFtMAuUqKgSxQEoCxEjCgALHhAB0cEMikAHVBDFNWmfgG5hAXwA0w2ck4BtALowEELrxTmDO7YUQp0WKZRp1YeAEQAxACVfJ1BIClx4JDQMTA9qWnptIA

💻 Code

const language = {
  set current(name: string) {
    this.log.push(name);
  },
  log: [] as string[],
};

language.current = "FR";

const c = language.current;

🙁 Actual behavior

Variable c is said to be of type string.

🙂 Expected behavior

As clearly stated here, it should be undefined.

Note that current is not defined, and any attempts to access it will result in undefined.

Additional information about the issue

No response

Start with the linked TypeScript Playground example and confirm that reading the setter-only property is typed as string rather than undefined. Trace the compiler logic that determines the type of an accessor read, then add coverage for this object-literal setter case and verify that the inferred type is undefined without regressing valid getter/setter behavior.