scala.tools.nsc.typechecker.Contexts

# Context

#### class Context extends AnyRef

A motley collection of the state and loosely associated behaviour of the type checker. Each `Typer` has an associated context, and as it descends into the tree new `(Typer, Context)` pairs are spawned.

Meet the crew; first the state:

- A tree, symbol, and scope representing the focus of the typechecker
- An enclosing context, `outer`.
- The current compilation unit.
- A variety of bits that track the current error reporting policy (more on this later); whether or not implicits/macros are enabled, whether we are in a self or super call or in a constructor suffix. These are represented as bits in the mask `contextMode`.
- Some odds and ends: undetermined type pararameters of the current line of type inference; contextual augmentation for error messages, tracking of the nesting depth.

And behaviour:

- The central point for issuing errors and warnings from the typechecker, with a means to buffer these for use in 'silent' type checking, when some recovery might be possible.

- `Context` is something of a Zipper for the tree were are typechecking: it `enclosingContextChain` is the path back to the root. This is exactly what we need to resolve names (`lookupSymbol`) and to collect in-scope implicit defintions (`implicitss`) Supporting these are `imports`, which represents all `Import` trees in in the enclosing context chain.
- In a similar vein, we can assess accessiblity (`isAccessible`.)

More on error buffering: When are type errors recoverable? In quite a few places, it turns out. Some examples: trying to type an application with/without the expected type, or with/without implicit views enabled. This is usually mediated by `Typer.silent`, `Inferencer#tryTwice`.

Intially, starting from the `typer` phase, the contexts either buffer or report errors; afterwards errors are thrown. This is configured in `rootContext`. Additionally, more fine grained control is needed based on the kind of error; ambiguity errors are often suppressed during exploraratory typing, such as determining whether `a == b` in an argument position is an assignment or a named argument, when `Infererencer#isApplicableSafe` type checks applications with and without an expected type, or whtn `Typer#tryTypedApply` tries to fit arguments to a function type with/without implicit views.

When the error policies entails error/warning buffering, the mutable ReportBuffer records everything that is issued. It is important to note, that child Contexts created with `make` "inherit" the very same `ReportBuffer` instance, whereas children spawned through `makeSilent` receive an separate, fresh buffer.

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AnyRef, Any
Known Subclasses
ImportContext, NoContext
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2. AnyRef
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2. by StringFormat
3. by Ensuring
4. by ArrowAssoc

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

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

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

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

   Definition Classes
     AnyRef → Any

6. #### def ambiguousErrors: Boolean

7. #### def apply(mask: ContextMode): Boolean

   Is this context in all modes in the given `mask`?

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

   Definition Classes
     Any

9. #### def bufferErrors: Boolean

10. #### def checking: Boolean

11. #### def checking_=(value: Boolean): Unit

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

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

13. #### var contextMode: ContextMode

    A bitmask containing all the boolean flags in a context, e.

    A bitmask containing all the boolean flags in a context, e.g. are implicit views enabled

14. #### def defaultModeForTyped: Mode

15. #### val depth: Int

16. #### var diagnostic: List[String]

    These messages are printed when issuing an error

17. #### var enclClass: Analyzer.Context

    The next outer context whose tree is a template or package definition

18. #### def enclClassOrMethod: Analyzer.Context

    The next enclosing context (potentially `this`) that is owned by a class or method

19. #### var enclMethod: Analyzer.Context

    The next outer context whose tree is a method

20. #### def enclosingApply: Analyzer.Context

    .

    ...or an Apply.

21. #### def enclosingCaseDef: Analyzer.Context

    The next enclosing context (potentially `this`) that has a `CaseDef` as a tree

22. #### def enclosingContextChain: List[Analyzer.Context]

23. #### def enclosingNonImportContext: Analyzer.Context

24. #### def enclosingSubClassContext(clazz: Global.Symbol): Analyzer.Context

    Return the closest enclosing context that defines a subclass of `clazz` or a companion object thereof, or `NoContext` if no such context exists.

25. #### def enrichmentEnabled: Boolean

26. #### def enrichmentEnabled_=(value: Boolean): Unit

27. #### def ensuring(cond: (Analyzer.Context) ⇒ Boolean, msg: ⇒ Any): Analyzer.Context

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

28. #### def ensuring(cond: (Analyzer.Context) ⇒ Boolean): Analyzer.Context

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

29. #### def ensuring(cond: Boolean, msg: ⇒ Any): Analyzer.Context

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

30. #### def ensuring(cond: Boolean): Analyzer.Context

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

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

    Definition Classes
      AnyRef

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

    Definition Classes
      AnyRef → Any

33. #### def error(pos: Global.Position, msg: String): Unit

    Issue/throw the given error message according to the current mode for error reporting.

34. #### def error(pos: Global.Position, err: Throwable): Unit

    Issue/throw the given `err` according to the current mode for error reporting.

35. #### def errors: Seq[Analyzer.AbsTypeError]

36. #### def extractUndetparams(): List[Global.Symbol]

    Return and clear the undetermined type parameters

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

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

38. #### def firstError: Option[Analyzer.AbsTypeError]

    The first error, if any, in the report buffer

39. #### def firstImport: Option[Analyzer.ImportInfo]

    Equivalent to `imports.headOption`, but more efficient

40. #### def flushAndIssueWarnings(): Unit

    Issue and clear all warnings from the report buffer

41. #### def flushAndReturnBuffer(): collection.immutable.Seq[Analyzer.AbsTypeError]

    Return and clear all errors from the report buffer

42. #### def flushBuffer(): Unit

    Clear all errors from the report buffer

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

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

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

    Definition Classes
      AnyRef → Any

45. #### def hasErrors: Boolean

    Does the report buffer contain any errors?

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

    Definition Classes
      AnyRef → Any

47. #### def implicitsEnabled: Boolean

48. #### def implicitsEnabled_=(value: Boolean): Unit

49. #### def implicitss: List[List[Analyzer.ImplicitInfo]]

50. #### def importedAccessibleSymbol(imp: Analyzer.ImportInfo, name: Global.Name): Global.Symbol

    The symbol with name `name` imported via the import in `imp`, if any such symbol is accessible from this context.

51. #### def imports: List[Analyzer.ImportInfo]

    The currently visible imports

52. #### def inConstructorSuffix: Boolean

53. #### def inConstructorSuffix_=(value: Boolean): Unit

54. #### def inPatAlternative: Boolean

55. #### def inPatAlternative_=(value: Boolean): Unit

56. #### def inReturnExpr: Boolean

57. #### def inSecondTry: Boolean

58. #### def inSecondTry_=(value: Boolean): Unit

59. #### def inSelfSuperCall: Boolean

60. #### def inSelfSuperCall_=(value: Boolean): Unit

61. #### final def inSilentMode(expr: ⇒ Boolean): Boolean

    returns

      true if the `expr` evaluates to true within a silent Context that incurs no errors

    Annotations
      @inline()

62. #### def inSuperInit: Boolean

63. #### def inSuperInit_=(value: Boolean): Unit

64. #### def inTypeConstructorAllowed: Boolean

65. #### def isAccessible(sym: Global.Symbol, pre: Global.Type, superAccess: Boolean = false): Boolean

    Is `sym` accessible as a member of `pre` in current context?

66. #### def isInPackageObject(sym: Global.Symbol, pkg: Global.Symbol): Boolean

    Is `sym` defined in package object of package `pkg`? Since sym may be defined in some parent of the package object, we cannot inspect its owner only; we have to go through the info of the package object.

    Is `sym` defined in package object of package `pkg`? Since sym may be defined in some parent of the package object, we cannot inspect its owner only; we have to go through the info of the package object. However to avoid cycles we'll check what other ways we can before pushing that way.

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

    Definition Classes
      Any

68. #### def isNameInScope(name: Global.Name): Boolean

69. #### def isRootImport: Boolean

70. #### def issue(err: Analyzer.AbsTypeError): Unit

    Issue/buffer/throw the given type error according to the current mode for error reporting.

71. #### def issueAmbiguousError(err: Analyzer.AbsTypeError): Unit

    Issue/buffer/throw the given implicit ambiguity error according to the current mode for error reporting.

72. #### def issueAmbiguousError(pre: Global.Type, sym1: Global.Symbol, sym2: Global.Symbol, err: Analyzer.AbsTypeError): Unit

    Issue/buffer/throw the given implicit ambiguity error according to the current mode for error reporting.

73. #### def lookup(name: Global.Name, expectedOwner: Global.Symbol): Global.Symbol

    Find a symbol in this context or one of its outers.

    Find a symbol in this context or one of its outers.

    Used to find symbols are owned by methods (or fields), they can't be found in some scope.

    Examples: companion module of classes owned by a method, default getter methods of nested methods. See NamesDefaults.scala

74. #### def lookupSymbol(name: Global.Name, qualifies: (Global.Symbol) ⇒ Boolean): Global.NameLookup

    Find the symbol of a simple name starting from this context.

    Find the symbol of a simple name starting from this context. All names are filtered through the "qualifies" predicate, the search continuing as long as no qualifying name is found.

75. #### def macrosEnabled: Boolean

76. #### def macrosEnabled_=(value: Boolean): Unit

77. #### def make(tree: Global.Tree, owner: Global.Symbol, scope: Global.Scope): Analyzer.Context

78. #### def make(tree: Global.Tree = tree, owner: Global.Symbol = owner, scope: Global.Scope = scope, unit: Global.CompilationUnit = unit): Analyzer.Context

    Construct a child context.

    Construct a child context. The parent and child will share the report buffer. Compare with `makeSilent`, in which the child has a fresh report buffer.

    If `tree` is an `Import`, that import will be avaiable at the head of `Context#imports`.

79. #### def makeConstructorContext: Analyzer.Context

    A context for typing constructor parameter ValDefs, super or self invocation arguments and default getters of constructors.

    A context for typing constructor parameter ValDefs, super or self invocation arguments and default getters of constructors. These expressions need to be type checked in a scope outside the class, cf. spec 5.3.1.

    This method is called by namer / typer where `this` is the context for the constructor DefDef. The owner of the resulting (new) context is the outer context for the Template, i.e. the context for the ClassDef. This means that class type parameters will be in scope. The value parameters of the current constructor are also entered into the new constructor scope. Members of the class however will not be accessible.

80. #### def makeImplicit(reportAmbiguousErrors: Boolean): Analyzer.Context

    Make a silent child context does not allow implicits.

    Make a silent child context does not allow implicits. Used to prevent chaining of implicit views.

81. #### def makeNewScope(tree: Global.Tree, owner: Global.Symbol): Analyzer.Context

    Make a child context that represents a new nested scope

82. #### def makeSilent(reportAmbiguousErrors: Boolean = ambiguousErrors, newtree: Global.Tree = tree): Analyzer.Context

    Make a child context that buffers errors and warnings into a fresh report buffer.

83. #### var namedApplyBlockInfo: Option[(Global.Tree, Analyzer.NamedApplyInfo)]

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

    Definition Classes
      AnyRef

85. #### def nextEnclosing(p: (Analyzer.Context) ⇒ Boolean): Analyzer.Context

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

    Definition Classes
      AnyRef

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

    Definition Classes
      AnyRef

88. #### var openImplicits: List[Analyzer.OpenImplicit]

    Types for which implicit arguments are currently searched

89. #### final def outer: Analyzer.Context

90. #### def outerDepth: Int

    Attributes
      protected

91. #### val owner: Global.Symbol

    The current owner

92. #### var prefix: Global.Type

93. #### def pushTypeBounds(sym: Global.Symbol): Unit

94. #### def reportBuffer: Analyzer.ReportBuffer

    A buffer for errors and warnings, used with `this.bufferErrors == true`

95. #### def reportErrors: Boolean

96. #### def resetCache(): Unit

97. #### def restoreReportBuffer(other: Analyzer.ReportBuffer): Unit

    Discard the current report buffer, and replace with `other`

98. #### def restoreTypeBounds(tp: Global.Type): Global.Type

99. #### def returnsSeen: Boolean

100. #### def returnsSeen_=(value: Boolean): Unit

101. #### def retyping: Boolean

102. #### def retyping_=(value: Boolean): Unit

103. #### var savedTypeBounds: List[(Global.Symbol, Global.Type)]

     Saved type bounds for type parameters which are narrowed in a GADT.

104. #### def savingUndeterminedTypeParams[A](reportAmbiguous: Boolean = ambiguousErrors)(body: ⇒ A): A

     Run `body` with this context with no undetermined type parameters, restore the original the original list afterwards.

     Run `body` with this context with no undetermined type parameters, restore the original the original list afterwards.

     reportAmbiguous

       Should ambiguous errors be reported during evaluation of `body`?

105. #### val scope: Global.Scope

     The current scope

106. #### def set(enable: ContextMode = NOmode, disable: ContextMode = NOmode): Context.this.type

     Set all modes in the mask `enable` to true, and all in `disable` to false.

107. #### def setAmbiguousErrors(report: Boolean): Unit

108. #### def setBufferErrors(): Unit

109. #### def setReportErrors(): Unit

110. #### def setThrowErrors(): Unit

111. #### def siteString: String

112. #### def starPatterns: Boolean

113. #### def starPatterns_=(value: Boolean): Unit

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

     Definition Classes
       AnyRef

115. #### def throwErrors: Boolean

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

     Definition Classes
       Context → AnyRef → Any

117. #### val tree: Global.Tree

     Tree associated with this context

118. #### def undetparams: List[Global.Symbol]

     Undetermined type parameters.

     Undetermined type parameters. See `Infer#{inferExprInstance, adjustTypeArgs}`. Not inherited to child contexts

119. #### def undetparamsString: String

120. #### def undetparams_=(ps: List[Global.Symbol]): Unit

121. #### val unit: Global.CompilationUnit

122. #### def update(mask: ContextMode, value: Boolean): Unit

     Update all modes in `mask` to `value`

123. #### def updateBuffer(errors: Traversable[Analyzer.AbsTypeError]): Analyzer.ReportBuffer

     Append the given errors to the report buffer

124. #### def useFreshReportBuffer(): Unit

     Discard the current report buffer, and replace with an empty one

125. #### var variance: Variance

     Variance relative to enclosing class

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

     Definition Classes
       AnyRef
     Annotations
       @throws( ... )

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

     Definition Classes
       AnyRef
     Annotations
       @throws( ... )

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

     Definition Classes
       AnyRef
     Annotations
       @throws( ... )

129. #### def warning(pos: Global.Position, msg: String, force: Boolean = false): Unit

     Issue/throw the given error message according to the current mode for error reporting.

130. #### final def withImplicitsDisabled[T](op: ⇒ T): T

     Annotations
       @inline()

131. #### final def withImplicitsDisabledAllowEnrichment[T](op: ⇒ T): T

     Annotations
       @inline()

132. #### final def withImplicitsEnabled[T](op: ⇒ T): T

     Annotations
       @inline()

133. #### final def withMacrosDisabled[T](op: ⇒ T): T

     Annotations
       @inline()

134. #### final def withMacrosEnabled[T](op: ⇒ T): T

     Annotations
       @inline()

135. #### def withMode[T](enabled: ContextMode = NOmode, disabled: ContextMode = NOmode)(op: ⇒ T): T

     Annotations
       @inline()

136. #### final def withOnlyStickyModes[T](op: ⇒ T): T

     Annotations
       @inline()

137. #### final def withinPatAlternative[T](op: ⇒ T): T

     Annotations
       @inline()

138. #### final def withinReturnExpr[T](op: ⇒ T): T

     Annotations
       @inline()

139. #### final def withinSecondTry[T](op: ⇒ T): T

     Annotations
       @inline()

140. #### final def withinStarPatterns[T](op: ⇒ T): T

     Annotations
       @inline()

141. #### final def withinSuperInit[T](op: ⇒ T): T

     Annotations
       @inline()

142. #### final def withinTypeConstructorAllowed[T](op: ⇒ T): T

     TypeConstructorAllowed is enabled when we are typing a higher-kinded type.

     TypeConstructorAllowed is enabled when we are typing a higher-kinded type. adapt should then check kind-arity based on the prototypical type's kind arity. Type arguments should not be inferred.

     Annotations
       @inline()

143. #### def →[B](y: B): (Analyzer.Context, B)

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

### Inherited from AnyRef

### Inherited from Any

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

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

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

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

### Ungrouped