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For the very small price of annotating types as Any/AnyVal in those
cases where we wish to use them, we can obtain useful warnings.
I made trunk clean against this warning and found several bugs
or at least suboptimalities in the process.
I put the warning behind -Xlint for the moment, but I think this
belongs on by default, even for this alone:
scala> List(1, 2, 3) contains "a"
<console>:8: warning: a type was inferred to be `Any`; this may indicate a programming error.
List(1, 2, 3) contains "a"
^
res0: Boolean = false
Or this punishment meted out by SI-4042:
scala> 1l to 5l contains 5
<console>:8: warning: a type was inferred to be `AnyVal`; this may indicate a programming error.
1l to 5l contains 5
^
res0: Boolean = false
A different situation where this arises, which I have seen variations
of many times:
scala> class A[T](default: T) {
def get(x: => Option[T]) = x getOrElse Some(default)
}
<console>:7: warning: a type was inferred to be `Any`; this may indicate a programming error.
class A[T](default: T) { def get(x: => Option[T]) = x getOrElse Some(default) }
^
// Oops, this was what I meant
scala> class A[T](default: T) {
def get(x: => Option[T]) = x getOrElse default
}
defined class A
Harder to avoid spurious warnings when "Object" is inferred.
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