与默认构造函数参数的隐式转换相关的奇怪 Scala 错误

发布于 2024-10-11 03:13:55 字数 902 浏览 0 评论 0原文

考虑文件 bug.scala：

package sandbox

object Foo {
  implicit def stringToInt(s: String) = 5
}

import Foo._

class Boo(val a: Int = "foo" / 3) {
  val b: Int = "foo" / 3
  def c(d: Int = "foo" / 3) = d
}

它定义了一个隐式转换，导入它，并在三个略有不同的场景中使用它。编译它：

E:\prog\scala\test>scalac bug.scala
bug.scala:9: error: value / is not a member of java.lang.String
class Boo(val a: Int = "foo" / 3) {
                       ^
one error found

隐式转换在用于默认构造函数参数时似乎不起作用，但适用于其他场景。

现在看一下：

package sandbox

object Foo {
  implicit def stringToInt(s: String) = 5
}

object dummy

import Foo._
import dummy._

class Boo(val a: Int = "foo" / 3) {
  val b: Int = "foo" / 3
  def c(d: Int = "foo" / 3) = d
}

我们只是添加了一个空对象并将其导入。现在文件编译没有错误！

我在这里看到两种可能性：1）我的头脑混乱。 2) 编译器存在错误。谁能确认是后者吗？

（使用 Scala 2.8.1。）

原文

Consider the file bug.scala:

package sandbox

object Foo {
  implicit def stringToInt(s: String) = 5
}

import Foo._

class Boo(val a: Int = "foo" / 3) {
  val b: Int = "foo" / 3
  def c(d: Int = "foo" / 3) = d
}

It defines an implicit conversion, imports it, and uses it in three slightly different scenarios. Compile it:

E:\prog\scala\test>scalac bug.scala
bug.scala:9: error: value / is not a member of java.lang.String
class Boo(val a: Int = "foo" / 3) {
                       ^
one error found

The implicit conversion seems not to be working when used for a default constructor parameter, but works for the other scenarios.

Now watch this:

package sandbox

object Foo {
  implicit def stringToInt(s: String) = 5
}

object dummy

import Foo._
import dummy._

class Boo(val a: Int = "foo" / 3) {
  val b: Int = "foo" / 3
  def c(d: Int = "foo" / 3) = d
}

We've simply added an empty object and imported it. Now the file compiles without errors!

I see two possibilities here: 1) My head is messing with me. 2) There's a bug in the compiler. Can anyone confirm it's the latter?

(Using Scala 2.8.1.)

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