Instantiable types from return types of contextual signatures don't provide contextual type information for return expressions

还没有人认领这个 Issue。

### 🔎 Search Terms

instantiable contextual signature return types

### 🕗 Version & Regression Information

- This is the behavior in every version I tried

### ⏯ Playground Link

https://www.typescriptlang.org/play/?ts=5.8.0-dev.20250216#code/C4TwDgpgBAwg9gO2BAHsAysAhsgzlAXgCgooAfKAbxNNt22AFdcAuKAIgBs4sATASwQBzdgG4atKLxxY2CRp07jJAXxoVqk0vRzM27XIwDGRiLlxiJtadjb0AToKHLaK8UV4QjnLPegAzRgQjYH5EKCM-HAhMOD8AHgAVeCRUYAA+AAoaI0RkNDZkvLSAGhzEf34hNk1aRDYAJS843niHJxKoTJCUQpT84ABKQnSoItS0dJcVMsG2ADc4fl53XIR6KHo46AIIqORYv2zSWu0GPQ5uPid2MskbWSh5RTuoFSgsfH60zGjcV9OUHqVCspH8EGARgAFmxMsMCKNMoDJDomKwOIYTGYLK8tFIZPooRBFHBbqC3oNcW9XjMiINxEA

### 💻 Code

```ts
type ContextStates =
| {
status: "loading";
data: null;
}
| {
status: "success";
data: string;
};

declare function createStore(
context: TContext,
config: {
on: Record TContext>;
},
): void;

const store = createStore(
{
status: "loading",
data: null,
} as ContextStates,
{
on: {
fetch: () => ({
status: "success",
data: "hello",
}),
},
},
);
```

### 🙁 Actual behavior

`status: "success",` errors

### 🙂 Expected behavior

no error

### Additional information about the issue

Making `(ctx: TContext) => TContext` into a type parameter makes it work (see [TS playground](https://www.typescriptlang.org/play/?ts=5.8.0-dev.20250216#code/C4TwDgpgBAwg9gO2BAHsAysAhsgzlAXgCgooAfKAbxNNt22AFdcAuKAIgBs4sATASwQBzdgG4atKLxxY2CRp07jJAXxoVqk0vRzM27XIwDGRiLlxiJtadjb0AToKHLaK8UV4QjnLPegAzRgQjYH5EKCM-HAhMOD8AHhoAFXgkVGAAGmSk+ywEXH5Q8PSIBF58AAoQlDYUxGQ0AEpCAD4oOrS0LJaKmiN69NrUhsy+xH9+ITZNWkQ2ACUvON54hycM9py8gqKEFpcVLMa2ADc4fl53fvzgKHo46AIIqORYv17SGe0GPQ5uPic7Cykhssig8kUwKgKigWHww3SmGiuChXygcyoVlI-ggwCMAAs2BVmgQ2hU0ZIdExWBxDCYzBYoVopDJ9PiIIo4ECsdDGkzoVDDkRGuIgA)) but that's not natural to write and isn't broadly applicable as a workaround

首先运行链接的 TypeScript Playground 复现，并将其与提供的泛型类型变通方案进行比较。调查为什么上下文签名中的返回表达式会被拒绝，并在原始示例无需该变通方案即可通过类型检查时，视为 issue 完成。

由索引模型根据 Issue 内容生成。