Generic indexed access on a substitution type with an array constraint resolves incorrectly

从链接的 TypeScript Playground 复现开始，将失败的泛型索引访问分支与添加了数组类型别名的可用变体进行比较。阅读 PR 48837 中讨论的行为，然后验证原始示例不再报告约束错误，同时保留预期的推断映射类型行为。

🔎 Search Terms

indexed access substitution type array constraint

🕗 Version & Regression Information

• This is the behavior in every version I tried

⏯ Playground Link

https://www.typescriptlang.org/play?#code/C4TwDgpgBAMglsCAnAhgGwCrmgXigZ2CTgDsBzKAHyhIFcBbAI2SqkYHt20IUSBuAFChIUAGrpaEAOIRgiJAB5xaSVhEQAHohIATfLATJ0a3AfnHsAPih4AFAEob15auyCh2KAGUAxgAsIehQbb39AlABBJFQQVl8AoIB5RgArCB9gVnhzTDcPEXjwqJiQ4pQQBUKk1PTM6irI6PKsw1RcyEtBYWgG5LSMkIBvASgoAG0AawgQAC4CIlIyAF053pqB+rCgstjqbKN2iEEAX3duqABJEgAzZBcIfAAxJHZ6BsqoTW09UISUazwXk+Wggun0+zaJhGUAA-GIJNJZPJKpZoatgd99A0dtC4cNRgTxgBpKCkKBTEDsa7eFaXG53BFPF5vLYoSpjIlLTrQ0bHNHeDGgn5rfrAXFQfGE4mkkjk6ZUmlzK63JD3Jmvd5eDlcwSEvmjOYkCAAN2QgiAA

💻 Code

type LiteralType = string | number | boolean;
type ValueGetter<ValueType extends LiteralType = LiteralType> = () => ValueType;

type Schema = SchemaArray | SchemaObject | LiteralType;
type SchemaArray = Array<SchemaObject | SchemaArray | LiteralType>;
type SchemaObject = {
  [key: string]: SchemaObject | SchemaArray | LiteralType;
};

type InferValuesFromSchema<S extends Schema> = S extends LiteralType
  ? ValueGetter<S>
  : S extends SchemaArray
  ? {
      [K in keyof S]: InferValuesFromSchema<S[K]>;
    }
  : S extends SchemaObject
  ? {
      [K in keyof S]: InferValuesFromSchema<S[K]>;
    }
  : never;

🙁 Actual behavior

an error is reported:

Type 'S[K]' does not satisfy the constraint 'Schema'.
  Type 'S[keyof S]' is not assignable to type 'Schema'.
    Type 'S[string] | S[number] | S[symbol]' is not assignable to type 'Schema'.
      Type 'S[string]' is not assignable to type 'Schema'.
        Type 'S[string]' is not assignable to type 'SchemaObject'.
          Type 'S[keyof S]' is not assignable to type 'SchemaObject'.
            Type 'S[K]' is not assignable to type 'SchemaObject'.
              Type 'S[keyof S]' is not assignable to type 'SchemaObject'.
                Type 'S[string] | S[number] | S[symbol]' is not assignable to type 'SchemaObject'.
                  Type 'S[string]' is not assignable to type 'SchemaObject'.(2344)

🙂 Expected behavior

There should be no error, S[K] should satisfy Schema constraint (at least since https://github.com/microsoft/TypeScript/pull/48837 )

Additional information about the issue

A variant with an additional type alias for that array branch works OK: TS playground.