使用泛型重载Scala方法

Question

带有两个重载方法编译的示例代码（Scala 2.11.8），如预期的那样：

def foo(p: Int, t: Double): Unit = {}
def foo(r: Int => Double): Unit = {}

foo(0, 0) // 1st method
foo(x => x.toDouble) // 2nd method

添加了通用参数的相同代码：

def fooGeneric[T](p: T, t: Double): Unit = {}
def fooGeneric[T](r: T => Double): Unit = {}

fooGeneric[Int](1, 1) // 1st method
fooGeneric[Int]((x: Int) => x.toDouble) //2nd method

fooGeneric[Int](x => x.toDouble) // does not compile

产生以下编译错误：

Error:(112, 19) missing parameter type
fooGeneric[Int](x => x.toDouble)

方法解析似乎没有歧义，但编译器无法找到匹配项。为什么呢？