Packages

  • package root

    The Scala compiler and reflection APIs.

    The Scala compiler and reflection APIs.

    Definition Classes
    root
  • package scala
    Definition Classes
    root
  • package tools
    Definition Classes
    scala
  • package nsc
    Definition Classes
    tools
  • package typechecker
    Definition Classes
    nsc
  • trait Checkable extends AnyRef

    On pattern matcher checkability:

    On pattern matcher checkability:

    The spec says that case _: List[Int] should be always issue an unchecked warning:

    > Types which are not of one of the forms described above are > also accepted as type patterns. However, such type patterns > will be translated to their erasure (§3.7). The Scala compiler > will issue an “unchecked” warning for these patterns to flag > the possible loss of type-safety.

    But the implementation goes a little further to omit warnings based on the static type of the scrutinee. As a trivial example:

    def foo(s: Seq[Int]) = s match { case _: List[Int] => }

    need not issue this warning.

    Consider a pattern match of this form: (x: X) match { case _: P => }

    There are four possibilities to consider: [P1] X will always conform to P [P2] x will never conform to P [P3] X will conform to P if some runtime test is true [P4] X cannot be checked against P

    The first two cases correspond to those when there is enough static information to say X <: P or that (x ∈ X) ⇒ (x ∉ P). The fourth case includes unknown abstract types or structural refinements appearing within a pattern.

    The third case is the interesting one. We designate another type, XR, which is essentially the intersection of X and |P|, where |P| is the erasure of P. If XR <: P, then no warning is emitted.

    We evaluate "X with conform to P" by checking X <: P_wild, where P_wild is the result of substituting wildcard types in place of pattern type variables. This is intentionally stricter than (X matchesPattern P), see scala/bug#8597 for motivating test cases.

    Examples of how this info is put to use: sealed trait A[T] ; class B[T] extends A[T] def f(x: B[Int]) = x match { case _: A[Int] if true => } def g(x: A[Int]) = x match { case _: B[Int] => }

    f requires no warning because X=B[Int], P=A[Int], and B[Int] <:< A[Int]. g requires no warning because X=A[Int], P=B[Int], XR=B[Int], and B[Int] <:< B[Int]. XR=B[Int] because a value of type A[Int] which is tested to be a B can only be a B[Int], due to the definition of B (B[T] extends A[T].)

    This is something like asSeenFrom, only rather than asking what a type looks like from the point of view of one of its base classes, we ask what it looks like from the point of view of one of its subclasses.

    Definition Classes
    typechecker
  • InferCheckable

trait InferCheckable extends AnyRef

Self Type
Analyzer.Inferencer
Source
Checkable.scala
Linear Supertypes
AnyRef, Any
Known Subclasses
Inferencer
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Inherited
  1. InferCheckable
  2. AnyRef
  3. Any
Implicitly
  1. by any2stringadd
  2. by StringFormat
  3. by Ensuring
  4. by ArrowAssoc
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Visibility
  1. Public
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Value Members

  1. final def !=(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  2. final def ##(): Int
    Definition Classes
    AnyRef → Any
  3. def +(other: String): String
    Implicit
    This member is added by an implicit conversion from Analyzer.InferCheckable to any2stringadd[Analyzer.InferCheckable] performed by method any2stringadd in scala.Predef.
    Definition Classes
    any2stringadd
  4. def ->[B](y: B): (Analyzer.InferCheckable, B)
    Implicit
    This member is added by an implicit conversion from Analyzer.InferCheckable to ArrowAssoc[Analyzer.InferCheckable] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
    ArrowAssoc
    Annotations
    @inline()
  5. final def ==(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  6. final def asInstanceOf[T0]: T0
    Definition Classes
    Any
  7. def checkCheckable(tree: Global.Tree, P0: Global.Type, X0: Global.Type, inPattern: Boolean, canRemedy: Boolean = false): Unit

    TODO: much better error positions.

    TODO: much better error positions. Kind of stuck right now because they just pass us the one tree. TODO: Eliminate inPattern, canRemedy, which have no place here.

    Instead of the canRemedy flag, annotate uncheckable types that have become checkable because of the availability of a class tag?

  8. def clone(): AnyRef
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( ... ) @native()
  9. def ensuring(cond: (Analyzer.InferCheckable) ⇒ Boolean, msg: ⇒ Any): Analyzer.InferCheckable
    Implicit
    This member is added by an implicit conversion from Analyzer.InferCheckable to Ensuring[Analyzer.InferCheckable] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  10. def ensuring(cond: (Analyzer.InferCheckable) ⇒ Boolean): Analyzer.InferCheckable
    Implicit
    This member is added by an implicit conversion from Analyzer.InferCheckable to Ensuring[Analyzer.InferCheckable] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  11. def ensuring(cond: Boolean, msg: ⇒ Any): Analyzer.InferCheckable
    Implicit
    This member is added by an implicit conversion from Analyzer.InferCheckable to Ensuring[Analyzer.InferCheckable] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  12. def ensuring(cond: Boolean): Analyzer.InferCheckable
    Implicit
    This member is added by an implicit conversion from Analyzer.InferCheckable to Ensuring[Analyzer.InferCheckable] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  13. final def eq(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  14. def equals(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  15. def finalize(): Unit
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( classOf[java.lang.Throwable] )
  16. def formatted(fmtstr: String): String
    Implicit
    This member is added by an implicit conversion from Analyzer.InferCheckable to StringFormat[Analyzer.InferCheckable] performed by method StringFormat in scala.Predef.
    Definition Classes
    StringFormat
    Annotations
    @inline()
  17. final def getClass(): Class[_]
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  18. def hashCode(): Int
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  19. def isCheckable(P0: Global.Type): Boolean
  20. final def isInstanceOf[T0]: Boolean
    Definition Classes
    Any
  21. def isUncheckable(P0: Global.Type): Boolean
  22. final def ne(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  23. final def notify(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  24. final def notifyAll(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  25. final def synchronized[T0](arg0: ⇒ T0): T0
    Definition Classes
    AnyRef
  26. def toString(): String
    Definition Classes
    AnyRef → Any
  27. final def wait(): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  28. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  29. final def wait(arg0: Long): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... ) @native()
  30. def →[B](y: B): (Analyzer.InferCheckable, B)
    Implicit
    This member is added by an implicit conversion from Analyzer.InferCheckable to ArrowAssoc[Analyzer.InferCheckable] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
    ArrowAssoc

Inherited from AnyRef

Inherited from Any

Inherited by implicit conversion any2stringadd from Analyzer.InferCheckable to any2stringadd[Analyzer.InferCheckable]

Inherited by implicit conversion StringFormat from Analyzer.InferCheckable to StringFormat[Analyzer.InferCheckable]

Inherited by implicit conversion Ensuring from Analyzer.InferCheckable to Ensuring[Analyzer.InferCheckable]

Inherited by implicit conversion ArrowAssoc from Analyzer.InferCheckable to ArrowAssoc[Analyzer.InferCheckable]

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