microsoft / microsoft/TypeScript

Property is not assignable to the same property in generic base type

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Bug Domain: check: Variance Relationships Help Wanted
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描述

### 🔎 Search Terms

Property is not assignable to the same property in generic base type

### 🕗 Version & Regression Information

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

### ⏯ Playground Link

https://www.typescriptlang.org/zh/play/?ts=5.8.3#code/IYIwzgLgTsDGEAJYBthjAgSgCwPYIG8AoBBUSGeBABwEsATAc1oDswAeAMQH0BRBAKYAPCAJb0MLAK4BbEAKgAaBDwBSAPgAUIKFLABHKQMgAuFd1UIAPud4BKM2uu2A3EQC+RFGgwAhZFIAZoEKgiJiElh4hCQ0DMxsXHxhouKSsvJK5hraugZGptnOPPaOFsXJscSkpFACEFJQLKQ6eobGEG6knp5AA

### 💻 Code

```ts
abstract class Rho {
abstract pidgins(brusquest: F_J | F_E): F_J | F_E;
}
class Bluffer extends Rho {
pidgins(brusquest: F_J | F_E): F_J | F_E
{
return brusquest;
}
}

```

### 🙁 Actual behavior

Property 'pidgins' in type 'Bluffer' is not assignable to the same property in base type 'Rho'.
Type '(brusquest: F_E | F_J) => F_E | F_J' is not assignable to type '(brusquest: F_E | F_J) => F_E | F_J'. Two different types with this name exist, but they are unrelated.
Type 'number | F_E | F_J' is not assignable to type 'F_E | F_J'.
Type 'number' is not assignable to type 'F_E | F_J'.(2416)

### 🙂 Expected behavior

No error

### Additional information about the issue

The following works with no error:
```
abstract class Rho {
abstract pidgins(brusquest: F_J | F_E): F_J | F_E;
abstract pidgins(brusquest: F_J | F_E): F_J | F_E;
}
class Bluffer extends Rho {
pidgins(brusquest: F_J | F_E): F_J | F_E
{
return brusquest;
}
}

```

贡献指南

打开贡献指南

调研方向

首先复现链接的 TypeScript Playground 中的示例,并将 Rho 中的泛型方法与 Bluffer 中的实现进行比较。跟踪泛型方法兼容性的类型检查路径;当复现结果不报告错误,且不破坏相关的可赋值性行为时,即表示完成。

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评估

技术栈
typescript
领域
compilers
Issue 类型
缺陷
难度
4/5
预计耗时
3-5 天
活跃度
停滞
描述清晰度
基本清楚
新手友好度
35/100

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