scala.tools.nsc.typechecker.Infer

# Inferencer

###
Related Doc: package Infer

#### abstract class Inferencer extends Analyzer.InferencerContextErrors with Analyzer.InferCheckable

The context-dependent inferencer part

Source
  Infer.scala

Linear Supertypes
Analyzer.InferCheckable, Analyzer.InferencerContextErrors, AnyRef, Any
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Inherited

1. Inferencer
2. InferCheckable
3. InferencerContextErrors
4. AnyRef
5. Any

Implicitly

1. by any2stringadd
2. by StringFormat
3. by Ensuring
4. by ArrowAssoc

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Visibility

1. Public
2. All

### Instance Constructors

1. #### new Inferencer()

### Abstract Value Members

1. #### abstract def context: Analyzer.Context

### Concrete Value Members

1. #### final def !=(arg0: Any): Boolean

   Test two objects for inequality.

   Test two objects for inequality.

   returns

     `true` if !(this == that), false otherwise.

   Definition Classes
     AnyRef → Any

2. #### final def ##(): Int

   Equivalent to `x.hashCode` except for boxed numeric types and `null`.

   Equivalent to `x.hashCode` except for boxed numeric types and `null`. For numerics, it returns a hash value which is consistent with value equality: if two value type instances compare as true, then ## will produce the same hash value for each of them. For `null` returns a hashcode where `null.hashCode` throws a `NullPointerException`.

   returns

     a hash value consistent with ==

   Definition Classes
     AnyRef → Any

3. #### def +(other: String): String

   Implicit information
     This member is added by an implicit conversion from Analyzer.Inferencer to any2stringadd[Analyzer.Inferencer] performed by method any2stringadd in scala.Predef.
   Definition Classes
     any2stringadd

4. #### def ->[B](y: B): (Analyzer.Inferencer, B)

   Implicit information
     This member is added by an implicit conversion from Analyzer.Inferencer to ArrowAssoc[Analyzer.Inferencer] performed by method ArrowAssoc in scala.Predef.
   Definition Classes
     ArrowAssoc
   Annotations
     @inline()

5. #### final def ==(arg0: Any): Boolean

   The expression `x == that` is equivalent to `if (x eq null) that eq null else x.equals(that)`.

   The expression `x == that` is equivalent to `if (x eq null) that eq null else x.equals(that)`.

   returns

     `true` if the receiver object is equivalent to the argument; `false` otherwise.

   Definition Classes
     AnyRef → Any

6. #### object AdjustedTypeArgs

   [Martin] Can someone comment this please? I have no idea what it's for and the code is not exactly readable.

7. #### object InferErrorGen

   Definition Classes
     InferencerContextErrors

8. #### def adjustTypeArgs(tparams: List[Global.Symbol], tvars: List[Global.TypeVar], targs: List[Global.Type], restpe: Global.Type = WildcardType): Result

   Retract arguments that were inferred to Nothing because inference failed.

   Retract arguments that were inferred to Nothing because inference failed. Correct types for repeated params.

   We detect Nothing-due-to-failure by only retracting a parameter if either:

   - it occurs in an invariant/contravariant position in `restpe`
   - `restpe == WildcardType`

   Retracted parameters are mapped to None. TODO:

   - make sure the performance hit of storing these in a map is acceptable (it's going to be a small map in 90% of the cases, I think)
   - refactor further up the callstack so that we don't have to do this post-factum adjustment?

   Rewrite for repeated param types: Map T* entries to Seq[T].

   returns

     map from tparams to inferred arg, if inference was successful, tparams that map to None are considered left undetermined type parameters that are inferred as `scala.Nothing` and that are not covariant in `restpe` are taken to be undetermined

9. #### object approximateAbstracts extends Global.TypeMap

10. #### final def asInstanceOf[T0]: T0

    Cast the receiver object to be of type `T0`.

    Cast the receiver object to be of type `T0`.

    Note that the success of a cast at runtime is modulo Scala's erasure semantics. Therefore the expression `1.asInstanceOf[String]` will throw a `ClassCastException` at runtime, while the expression `List(1).asInstanceOf[List[String]]` will not. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the requested type.

    returns

      the receiver object.

    Definition Classes
      Any
    Exceptions thrown

      `ClassCastException` if the receiver object is not an instance of the erasure of type `T0`.

11. #### def checkAccessible(tree: Global.Tree, sym: Global.Symbol, pre: Global.Type, site: Global.Tree): Global.Tree

    Check that `sym` is defined and accessible as a member of tree `site` with type `pre` in current context.

12. #### def checkBounds(tree: Global.Tree, pre: Global.Type, owner: Global.Symbol, tparams: List[Global.Symbol], targs: List[Global.Type], prefix: String): Boolean

    error if arguments not within bounds.

13. #### 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.

    Definition Classes
      InferCheckable

14. #### def checkKindBounds(tparams: List[Global.Symbol], targs: List[Global.Type], pre: Global.Type, owner: Global.Symbol): List[String]

15. #### def clone(): AnyRef

    Create a copy of the receiver object.

    Create a copy of the receiver object.

    The default implementation of the `clone` method is platform dependent.

    returns

      a copy of the receiver object.

    Attributes
      protected[java.lang]
    Definition Classes
      AnyRef
    Annotations
      @throws( ... )
    Note

      not specified by SLS as a member of AnyRef

16. #### def eligibleForTupleConversion(formals: List[Global.Type], argsCount: Int): Boolean

17. #### def eligibleForTupleConversion(paramsCount: Int, argsCount: Int, varargsTarget: Boolean): Boolean

    True if the given parameter list can accept a tupled argument list, and the argument list can be tupled (based on its length.)

18. #### def ensureFullyDefined(tp: Global.Type): Global.Type

19. #### def ensuring(cond: (Analyzer.Inferencer) ⇒ Boolean, msg: ⇒ Any): Analyzer.Inferencer

    Implicit information
      This member is added by an implicit conversion from Analyzer.Inferencer to Ensuring[Analyzer.Inferencer] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring

20. #### def ensuring(cond: (Analyzer.Inferencer) ⇒ Boolean): Analyzer.Inferencer

    Implicit information
      This member is added by an implicit conversion from Analyzer.Inferencer to Ensuring[Analyzer.Inferencer] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring

21. #### def ensuring(cond: Boolean, msg: ⇒ Any): Analyzer.Inferencer

    Implicit information
      This member is added by an implicit conversion from Analyzer.Inferencer to Ensuring[Analyzer.Inferencer] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring

22. #### def ensuring(cond: Boolean): Analyzer.Inferencer

    Implicit information
      This member is added by an implicit conversion from Analyzer.Inferencer to Ensuring[Analyzer.Inferencer] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring

23. #### final def eq(arg0: AnyRef): Boolean

    Tests whether the argument (`that`) is a reference to the receiver object (`this`).

    Tests whether the argument (`that`) is a reference to the receiver object (`this`).

    The `eq` method implements an equivalence relation on non-null instances of `AnyRef`, and has three additional properties:

    - It is consistent: for any non-null instances `x` and `y` of type `AnyRef`, multiple invocations of `x.eq(y)` consistently returns `true` or consistently returns `false`.
    - For any non-null instance `x` of type `AnyRef`, `x.eq(null)` and `null.eq(x)` returns `false`.
    - `null.eq(null)` returns `true`.

    When overriding the `equals` or `hashCode` methods, it is important to ensure that their behavior is consistent with reference equality. Therefore, if two objects are references to each other (`o1 eq o2`), they should be equal to each other (`o1 == o2`) and they should hash to the same value (`o1.hashCode == o2.hashCode`).

    returns

      `true` if the argument is a reference to the receiver object; `false` otherwise.

    Definition Classes
      AnyRef

24. #### def equals(arg0: Any): Boolean

    The equality method for reference types.

    The equality method for reference types. Default implementation delegates to `eq`.

    See also `equals` in scala.Any.

    returns

      `true` if the receiver object is equivalent to the argument; `false` otherwise.

    Definition Classes
      AnyRef → Any

25. #### def explainTypes(tp1: Global.Type, tp2: Global.Type): Unit

26. #### def finalize(): Unit

    Called by the garbage collector on the receiver object when there are no more references to the object.

    Called by the garbage collector on the receiver object when there are no more references to the object.

    The details of when and if the `finalize` method is invoked, as well as the interaction between `finalize` and non-local returns and exceptions, are all platform dependent.

    Attributes
      protected[java.lang]
    Definition Classes
      AnyRef
    Annotations
      @throws( classOf[java.lang.Throwable] )
    Note

      not specified by SLS as a member of AnyRef

27. #### def formatted(fmtstr: String): String

    Implicit information
      This member is added by an implicit conversion from Analyzer.Inferencer to StringFormat[Analyzer.Inferencer] performed by method StringFormat in scala.Predef.
    Definition Classes
      StringFormat
    Annotations
      @inline()

28. #### def freeTypeParamsOfTerms(tp: Global.Type): List[Global.Symbol]

    Collects type parameters referred to in a type.

29. #### final def getClass(): Class[_]

    A representation that corresponds to the dynamic class of the receiver object.

    A representation that corresponds to the dynamic class of the receiver object.

    The nature of the representation is platform dependent.

    returns

      a representation that corresponds to the dynamic class of the receiver object.

    Definition Classes
      AnyRef → Any
    Note

      not specified by SLS as a member of AnyRef

30. #### def getContext: Analyzer.Context

31. #### def hashCode(): Int

    The hashCode method for reference types.

    The hashCode method for reference types. See hashCode in scala.Any.

    returns

      the hash code value for this object.

    Definition Classes
      AnyRef → Any

32. #### def inferArgumentInstance(tree: Global.Tree, undetparams: List[Global.Symbol], strictPt: Global.Type, lenientPt: Global.Type): Unit

    Substitute free type variables `undetparams` of polymorphic argument expression `tree`, given two prototypes `strictPt`, and `lenientPt`.

    Substitute free type variables `undetparams` of polymorphic argument expression `tree`, given two prototypes `strictPt`, and `lenientPt`. `strictPt` is the first attempt prototype where type parameters are left unchanged. `lenientPt` is the fall-back prototype where type parameters are replaced by `WildcardType`s. We try to instantiate first to `strictPt` and then, if this fails, to `lenientPt`. If both attempts fail, an error is produced.

33. #### def inferConstructorInstance(tree: Global.Tree, undetparams: List[Global.Symbol], pt0: Global.Type): Unit

    Substitute free type variables `undetparams` of type constructor `tree` in pattern, given prototype `pt`.

    Substitute free type variables `undetparams` of type constructor `tree` in pattern, given prototype `pt`.

    tree

      the constructor that needs to be instantiated

    undetparams

      the undetermined type parameters

    pt0

      the expected result type of the instance

34. #### def inferExprAlternative(tree: Global.Tree, pt: Global.Type): Global.Tree

    Assign `tree` the symbol and type of the alternative which matches prototype `pt`, if it exists.

    Assign `tree` the symbol and type of the alternative which matches prototype `pt`, if it exists. If several alternatives match `pt`, take parameterless one. If no alternative matches `pt`, take the parameterless one anyway.

35. #### def inferExprInstance(tree: Global.Tree, tparams: List[Global.Symbol], pt: Global.Type = WildcardType, treeTp0: Global.Type = null, keepNothings: Boolean = true, useWeaklyCompatible: Boolean = false): List[Global.Symbol]

    Infer type arguments `targs` for `tparams` of polymorphic expression in `tree`, given prototype `pt`.

    Infer type arguments `targs` for `tparams` of polymorphic expression in `tree`, given prototype `pt`.

    Substitute `tparams` to `targs` in `tree`, after adjustment by `adjustTypeArgs`, returning the type parameters that were not determined If passed, infers against specified type `treeTp` instead of `tree.tp`.

36. #### def inferMethodAlternative(tree: Global.Tree, undetparams: List[Global.Symbol], argtpes0: List[Global.Type], pt0: Global.Type): Unit

    Assign `tree` the type of an alternative which is applicable to `argtpes`, and whose result type is compatible with `pt`.

    Assign `tree` the type of an alternative which is applicable to `argtpes`, and whose result type is compatible with `pt`. If several applicable alternatives exist, drop the alternatives which use default arguments, then select the most specialized one. If no applicable alternative exists, and pt != WildcardType, try again with pt = WildcardType. Otherwise, if there is no best alternative, error.

    argtpes0

      contains the argument types. If an argument is named, as "a = 3", the corresponding type is `NamedType("a", Int)`. If the name of some NamedType does not exist in an alternative's parameter names, the type is replaces by `Unit`, i.e. the argument is treated as an assignment expression.

37. #### def inferMethodInstance(fn: Global.Tree, undetparams: List[Global.Symbol], args: List[Global.Tree], pt0: Global.Type): List[Global.Symbol]

    Substitute free type variables `undetparams` of application `fn(args)`, given prototype `pt`.

    Substitute free type variables `undetparams` of application `fn(args)`, given prototype `pt`.

    fn

      fn: the function that needs to be instantiated.

    undetparams

      the parameters that need to be determined

    args

      the actual arguments supplied in the call.

    pt0

      the expected type of the function application

    returns

      The type parameters that remain uninstantiated, and that thus have not been substituted.

38. #### def inferModulePattern(pat: Global.Tree, pt: Global.Type): Unit

39. #### def inferPolyAlternatives(tree: Global.Tree, argtypes: List[Global.Type]): Unit

    Assign `tree` the type of all polymorphic alternatives which have the same number of type parameters as does `argtypes` with all argtypes are within the corresponding type parameter bounds.

    Assign `tree` the type of all polymorphic alternatives which have the same number of type parameters as does `argtypes` with all argtypes are within the corresponding type parameter bounds. If no such polymorphic alternative exist, error.

40. #### def inferTypedPattern(tree0: Global.Tree, pattp: Global.Type, pt0: Global.Type, canRemedy: Boolean): Global.Type

41. #### def instBounds(tvar: Global.TypeVar): Global.TypeBounds

42. #### def instantiateTypeVar(tvar: Global.TypeVar): Unit

43. #### def intersect(tp1: Global.Type, tp2: Global.Type): Global.Type

    Type intersection of simple type tp1 with general type tp2.

    Type intersection of simple type tp1 with general type tp2. The result eliminates some redundancies.

44. #### def isAsSpecific(ftpe1: Global.Type, ftpe2: Global.Type): Boolean

    Is type `ftpe1` strictly more specific than type `ftpe2` when both are alternatives in an overloaded function?

    Is type `ftpe1` strictly more specific than type `ftpe2` when both are alternatives in an overloaded function?

    See also

      SLS (sec:overloading-resolution)

45. #### def isCheckable(P0: Global.Type): Boolean

    Definition Classes
      InferCheckable

46. #### def isCoercible(tp: Global.Type, pt: Global.Type): Boolean

47. #### def isCompatibleArgs(tps: List[Global.Type], pts: List[Global.Type]): Boolean

48. #### def isConservativelyCompatible(tp: Global.Type, pt: Global.Type): Boolean

49. #### def isInProperSubClassOrObject(sym1: Global.Symbol, sym2: Global.Symbol): Boolean

    is symbol `sym1` defined in a proper subclass of symbol `sym2`?

50. #### final def isInstanceOf[T0]: Boolean

    Test whether the dynamic type of the receiver object is `T0`.

    Test whether the dynamic type of the receiver object is `T0`.

    Note that the result of the test is modulo Scala's erasure semantics. Therefore the expression `1.isInstanceOf[String]` will return `false`, while the expression `List(1).isInstanceOf[List[String]]` will return `true`. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the specified type.

    returns

      `true` if the receiver object is an instance of erasure of type `T0`; `false` otherwise.

    Definition Classes
      Any

51. #### def isInstantiatable(tvars: List[Global.TypeVar]): Boolean

52. #### def isProperSubClassOrObject(sym1: Global.Symbol, sym2: Global.Symbol): Boolean

    Is sym1 (or its companion class in case it is a module) a subclass of sym2 (or its companion class in case it is a module)?

53. #### def isStrictlyMoreSpecific(ftpe1: Global.Type, ftpe2: Global.Type, sym1: Global.Symbol, sym2: Global.Symbol): Boolean

54. #### def isUncheckable(P0: Global.Type): Boolean

    Definition Classes
      InferCheckable

55. #### def isWeaklyCompatible(tp: Global.Type, pt: Global.Type): Boolean

56. #### def makeFullyDefined(tp: Global.Type): Global.Type

    Replace any (possibly bounded) wildcard types in type `tp` by existentially bound variables.

57. #### def methTypeArgs(tparams: List[Global.Symbol], formals: List[Global.Type], restpe: Global.Type, argtpes: List[Global.Type], pt: Global.Type): Result

    Return inferred type arguments, given type parameters, formal parameters, argument types, result type and expected result type.

    Return inferred type arguments, given type parameters, formal parameters, argument types, result type and expected result type. If this is not possible, throw a `NoInstance` exception. Undetermined type arguments are represented by `definitions.NothingTpe`. No check that inferred parameters conform to their bounds is made here.

    tparams

      the type parameters of the method

    formals

      the value parameter types of the method

    restpe

      the result type of the method

    argtpes

      the argument types of the application

    pt

      the expected return type of the application

    returns

      @see adjustTypeArgs

    Exceptions thrown

58. #### final def ne(arg0: AnyRef): Boolean

    Equivalent to `!(this eq that)`.

    Equivalent to `!(this eq that)`.

    returns

      `true` if the argument is not a reference to the receiver object; `false` otherwise.

    Definition Classes
      AnyRef

59. #### final def notify(): Unit

    Wakes up a single thread that is waiting on the receiver object's monitor.

    Wakes up a single thread that is waiting on the receiver object's monitor.

    Definition Classes
      AnyRef
    Note

      not specified by SLS as a member of AnyRef

60. #### final def notifyAll(): Unit

    Wakes up all threads that are waiting on the receiver object's monitor.

    Wakes up all threads that are waiting on the receiver object's monitor.

    Definition Classes
      AnyRef
    Note

      not specified by SLS as a member of AnyRef

61. #### def protoTypeArgs(tparams: List[Global.Symbol], formals: List[Global.Type], restpe: Global.Type, pt: Global.Type): List[Global.Type]

    Return inferred proto-type arguments of function, given its type and value parameters and result type, and a prototype `pt` for the function result.

    Return inferred proto-type arguments of function, given its type and value parameters and result type, and a prototype `pt` for the function result. Type arguments need to be either determined precisely by the prototype, or they are maximized, if they occur only covariantly in the value parameter list. If instantiation of a type parameter fails, take WildcardType for the proto-type argument.

62. #### def setError[T <: Global.Tree](tree: T): T

63. #### final def synchronized[T0](arg0: ⇒ T0): T0

    Definition Classes
      AnyRef

64. #### object toOrigin extends Global.TypeMap

65. #### def toString(): String

    Creates a String representation of this object.

    Creates a String representation of this object. The default representation is platform dependent. On the java platform it is the concatenation of the class name, "@", and the object's hashcode in hexadecimal.

    returns

      a String representation of the object.

    Definition Classes
      AnyRef → Any

66. #### def tupleIfNecessary(formals: List[Global.Type], argtpes: List[Global.Type]): List[Global.Type]

    If the argument list needs to be tupled for the parameter list, a list containing the type of the tuple.

    If the argument list needs to be tupled for the parameter list, a list containing the type of the tuple. Otherwise, the original argument list.

67. #### final def wait(): Unit

    Definition Classes
      AnyRef
    Annotations
      @throws( ... )

68. #### final def wait(arg0: Long, arg1: Int): Unit

    Definition Classes
      AnyRef
    Annotations
      @throws( ... )

69. #### final def wait(arg0: Long): Unit

    Definition Classes
      AnyRef
    Annotations
      @throws( ... )

70. #### def →[B](y: B): (Analyzer.Inferencer, B)

    Implicit information
      This member is added by an implicit conversion from Analyzer.Inferencer to ArrowAssoc[Analyzer.Inferencer] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
      ArrowAssoc

### Inherited from Analyzer.InferCheckable

### Inherited from Analyzer.InferencerContextErrors

### Inherited from AnyRef

### Inherited from Any

### Inherited by implicit conversion any2stringadd from Analyzer.Inferencer to any2stringadd[Analyzer.Inferencer]

### Inherited by implicit conversion StringFormat from Analyzer.Inferencer to StringFormat[Analyzer.Inferencer]

### Inherited by implicit conversion Ensuring from Analyzer.Inferencer to Ensuring[Analyzer.Inferencer]

### Inherited by implicit conversion ArrowAssoc from Analyzer.Inferencer to ArrowAssoc[Analyzer.Inferencer]

### Ungrouped