2 不同类中具有相同名称的扩展方法在 Scala 3 中不起作用？

Question

我有以下场景：

case class B(v: String)
case class A(bs: Seq[B])

extension(a: A)
  def doit() = a.bs.map(_.doit()) // here is the exception

extension(b: B)
  def doit() = println("OK: ${b.v}")

这给了我以下编译异常：

value doit is not a member of B.
An extension method was tried, but could not be fully constructed:

    _$1

Scala 3中扩展方法的命名有限制吗？

请参阅Scastie上的示例

Answer 1

将评论变成答案，规范说这两个扩展都被翻译为def extension_doit.

显式调用扩展方法：

-- [E044] Cyclic Error: so.scala:7:45 -----------------------
7 |  extension(a: A) def doit() = a.bs.map(b => extension_doit(b)())
  |                                             ^
  |           Overloaded or recursive method extension_doit needs return type

这与调试原始示例时出现的错误相同：

>>>> StoredError: Overloaded or recursive method extension_doit needs return type
[snip]
-- [E008] Not Found Error: so.scala:7:42 --------------------
7 |  extension(a: A) def doit() = a.bs.map(_.doit())
  |                                        ^^^^^^
  |        value doit is not a member of B.
  |        An extension method was tried, but could not be fully constructed:
  |
  |            _$1

过载分辨率得到了明确的改进或​​扩展，以处理这种正常的重载情况，这些重载可能仅在后面的参数列表中进行区分。所以显然我们应该意识到脱糖形式是超载的。

Scala 2 也抱怨：

scala> object X { def f(i: Int) = f("") ; def f(s: String) = f(42) }
                                                              ^
       error: overloaded method f needs result type
                                   ^
       error: overloaded method f needs result type