Arrow functions behave inconsistently with classic functions

[Ryuurock]

🔎 Search Terms

Unable to get generic type, arrow function

🕗 Version & Regression Information

• This is a crash
• This problem exists in Nightly version
• This is the behavior in every version I tried

⏯ Playground Link

https://www.typescriptlang.org/play?ts=5.2.2#code/CYUwxgNghgTiAEAzArgOzAFwJYHtXzDigxAB4AoeK+AZQ2IRAA8TVgBneAJXBxmFLsMMLKgDmAGnhRUATwB8EytQAixKPGasO3Xv0HDRk6XMXKqAQUy5UnLSDacAFEIYAuWvRJTg6j2voASngAXnldMD4BIRFxKRkFJXknWDF2DwBvczEQDDp3eCdgsM8GAG5zKGs8dPgrbBqK6hyMAKgPItDwtoqAX0CPADccLGAK8kIQBics6ngW-JJO2bnqOAxkGHwM6Q8ARnhe80OlOZa2juLwldX4dc3t+AAjDwAmQ+Pe0+oqhtsXLwgHzqYI3VauEjHOYAemh8AAegB+KHUXz0FFUWEI5G3Kj3LbwMG4+AAL32GI+cyO-SAA

💻 Code

declare function create<
 State extends Record<string, any>,
 Data extends Record<string, any>,
 Actions extends (state: State, data: Data) => Record<string, any>,
>(args: {
 getState: () => State;
 actions: Actions;
 getData: () => Data;
}): void;

create({
 getState() {
 return { a: 1 }
 },
 getData: () => {
 return { b: 2 }
 },
 actions(state, data) {
 state
 // ^?
 data
 // ^?
 return {
 z: 1
 }
 }
})

🙁 Actual behavior

The getState and getData function types need to be consistent. For example, they are both arrow functions or ordinary functions to correctly infer the type. Otherwise, they cannot

🙂 Expected behavior

No matter what type of functions getState and getData are, the types can be correctly inferred in the actions function parameters.

Additional information about the issue

No response

[Andarist]

Your "ordinary functions" have a hidden this parameter - so they are actually context-sensitive here. This is essentially one of the cases that this issue is about: #47599

[typescript-bot]

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