tests/cases/compiler/inDoesNotOperateOnPrimitiveTypes.ts(19,17): error TS2361: The right-hand side of an 'in' expression must not be a primitive.
tests/cases/compiler/inDoesNotOperateOnPrimitiveTypes.ts(23,12): error TS2361: The right-hand side of an 'in' expression must not be a primitive.
tests/cases/compiler/inDoesNotOperateOnPrimitiveTypes.ts(27,12): error TS2361: The right-hand side of an 'in' expression must not be a primitive.
tests/cases/compiler/inDoesNotOperateOnPrimitiveTypes.ts(34,12): error TS2361: The right-hand side of an 'in' expression must not be a primitive.
tests/cases/compiler/inDoesNotOperateOnPrimitiveTypes.ts(53,14): error TS2361: The right-hand side of an 'in' expression must not be a primitive.
tests/cases/compiler/inDoesNotOperateOnPrimitiveTypes.ts(60,12): error TS2361: The right-hand side of an 'in' expression must not be a primitive.
tests/cases/compiler/inDoesNotOperateOnPrimitiveTypes.ts(64,12): error TS2361: The right-hand side of an 'in' expression must not be a primitive.


==== tests/cases/compiler/inDoesNotOperateOnPrimitiveTypes.ts (7 errors) ====
    const validHasKey = <T extends object>(
      thing: T,
      key: string,
    ): boolean => {
      return key in thing; // Ok
    };
    
    const alsoValidHasKey = <T>(
      thing: T,
      key: string,
    ): boolean => {
      return key in thing; // Ok (as T may be instantiated with a valid type)
    };
    
    function invalidHasKey<T extends string | number>(
      thing: T,
      key: string,
    ): boolean {
      return key in thing; // Error (because all possible instantiations are errors)
                    ~~~~~
!!! error TS2361: The right-hand side of an 'in' expression must not be a primitive.
    }
    
    function union1<T extends string | number, U extends boolean>(thing: T | U) {
      "key" in thing; // Error (because all possible instantiations are errors)
               ~~~~~
!!! error TS2361: The right-hand side of an 'in' expression must not be a primitive.
    }
    
    function union2<T extends object, U extends string | number>(thing: T | U) {
      "key" in thing; // Error (because narrowing is possible)
               ~~~~~
!!! error TS2361: The right-hand side of an 'in' expression must not be a primitive.
      if (typeof thing === "object") {
        "key" in thing; // Ok
      }
    }
    
    function union3<T>(thing: T | string | number) {
      "key" in thing; // Error (because narrowing is possible)
               ~~~~~
!!! error TS2361: The right-hand side of an 'in' expression must not be a primitive.
      if (typeof thing !== "string" && typeof thing !== "number") {
        "key" in thing; // Ok (because further narrowing is impossible)
      }
    }
    
    function union4<T extends object | "hello">(thing: T) {
      "key" in thing; // Ok (because narrowing is impossible)
    }
    
    function union5<T extends object | string, U extends object | number>(p: T | U) {
        // For consistency, this should probably not be an error, because useful
        // narrowing is impossible. However, this is exceptionally strange input,
        // and it adds a lot of complexity to distinguish between a `T | U` where
        // one constraint is non-primitive and the other is primitive and a `T | U`
        // like this where both constraints have primitive and non-primitive
        // constitutents. Also, the strictly sound behavior would be to error
        // here, which is what's happening, so "fixing" this by suppressing the
        // error seems very low-value.
        "key" in p;
                 ~
!!! error TS2361: The right-hand side of an 'in' expression must not be a primitive.
        if (typeof p === "object") {
            "key" in p;
        }
    }
    
    function intersection1<T extends number, U extends 0 | 1 | 2>(thing: T & U) {
      "key" in thing; // Error (because all possible instantiations are errors)
               ~~~~~
!!! error TS2361: The right-hand side of an 'in' expression must not be a primitive.
    }
    
    function intersection2<T>(thing: T & (0 | 1 | 2)) {
      "key" in thing; // Error (because all possible instantations are errors)
               ~~~~~
!!! error TS2361: The right-hand side of an 'in' expression must not be a primitive.
    }