scala.reflect.macros

# Context

#### trait Context extends Aliases with Enclosures with Names with Reifiers with FrontEnds with Infrastructure with Typers with Parsers with Evals with ExprUtils

EXPERIMENTAL

The Scala macros context.

See the overview page for a description of how macros work. This documentation entry provides information on the API available to macro writers.

A macro context wraps a compiler universe exposed in `universe` and having type scala.reflect.macros.Universe. This type is a refinement over the generic reflection API provided in scala.reflect.api.Universe. The extended Universe provides mutability for reflection artifacts (e.g. macros can change types of compiler trees, add annotation to symbols representing definitions, etc) and exposes some internal compiler functionality such as `Symbol.deSkolemize` or `Tree.attachments`.

Another fundamental part of a macro context is `macroApplication`, which provides access to the tree undergoing macro expansion. Parts of this tree can be found in arguments of the corresponding macro implementations and in `prefix`, but `macroApplication` gives the full picture.

Other than that, macro contexts provide facilities for typechecking, exploring the compiler's symbol table and enclosing trees and compilation units, evaluating trees, logging warnings/errors and much more. Refer to the documentation of top-level traits in this package to learn the details.

Source
  Context.scala

Linear Supertypes
ExprUtils, Evals, Parsers, Typers, Infrastructure, FrontEnds, Reifiers, Names, Enclosures, Aliases, AnyRef, Any
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Inherited

1. Context
2. ExprUtils
3. Evals
4. Parsers
5. Typers
6. Infrastructure
7. FrontEnds
8. Reifiers
9. Names
10. Enclosures
11. Aliases
12. AnyRef
13. Any

Implicitly

1. by any2stringadd
2. by any2stringfmt
3. by any2ArrowAssoc
4. by any2Ensuring

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### Type Members

1. #### type CompilationUnit = Universe.CompilationUnit

   The type of compilation units.

   The type of compilation units.

   Definition Classes
     Aliases

2. #### type Expr[+T] = Universe.Expr[T]

   Expr wraps an abstract syntax tree and tags it with its type.

   Expr wraps an abstract syntax tree and tags it with its type.

   Definition Classes
     Aliases

3. #### type Modifiers = Universe.Modifiers

   The type of tree modifiers.

   The type of tree modifiers.

   Definition Classes
     Aliases

4. #### type Name = Universe.Name

   The abstract type of names.

   The abstract type of names.

   Definition Classes
     Aliases

5. #### type Position = Universe.Position

   Defines a universe-specific notion of positions.

   Defines a universe-specific notion of positions.

   Definition Classes
     Aliases

6. #### abstract type PrefixType

   The type of the prefix tree from which the macro is selected.

   The type of the prefix tree from which the macro is selected. See the documentation entry for `prefix` for an example.

7. #### type Run = Universe.Run

   The type of compilation runs.

   The type of compilation runs.

   Definition Classes
     Aliases

8. #### type Scope = Universe.Scope

   The base type of all scopes.

   The base type of all scopes.

   Definition Classes
     Aliases

9. #### type Symbol = Universe.Symbol

   The type of symbols representing declarations.

   The type of symbols representing declarations.

   Definition Classes
     Aliases

10. #### type TermName = Universe.TermName

    The abstract type of names representing terms.

    The abstract type of names representing terms.

    Definition Classes
      Aliases

11. #### type Tree = Universe.Tree

    The type of Scala abstract syntax trees.

    The type of Scala abstract syntax trees.

    Definition Classes
      Aliases

12. #### type Type = Universe.Type

    The type of Scala types, and also Scala type signatures.

    The type of Scala types, and also Scala type signatures. (No difference is internally made between the two).

    Definition Classes
      Aliases

13. #### type TypeName = Universe.TypeName

    The abstract type of names representing types.

    The abstract type of names representing types.

    Definition Classes
      Aliases

14. #### type TypeTag[T] = Universe.TypeTag[T]

    The type of type tags.

    The type of type tags.

    Definition Classes
      Aliases

15. #### type WeakTypeTag[T] = Universe.WeakTypeTag[T]

    The type of weak type tags.

    The type of weak type tags.

    Definition Classes
      Aliases

### Abstract Value Members

1. #### abstract def Expr[T](tree: Tree)(implicit arg0: WeakTypeTag[T]): Expr[T]

   A shorthand to create an expr.

   A shorthand to create an expr.

   Unlike the conventional expr factory, which requires a scala.reflect.api.TreeCreator, this one accepts a regular tree, but the resulting exprs are unable of being migrated to other universes/mirrors (the functionality normally not needed for macros, since there is only one compile-time universe and only one compile-time mirror).

   Definition Classes
     Aliases

2. #### abstract def TypeTag[T](tpe: Type): TypeTag[T]

   A shorthand to create a type tag.

   A shorthand to create a type tag.

   Unlike the conventional type tag factory, which requires a scala.reflect.api.TypeCreator, this one accepts a regular type, but the resulting type tags are unable of being migrated to other universes/mirrors (the functionality normally not needed for macros, since there is only one compile-time universe and only one compile-time mirror).

   Definition Classes
     Aliases

3. #### abstract def WeakTypeTag[T](tpe: Type): WeakTypeTag[T]

   A shorthand to create a weak type tag.

   A shorthand to create a weak type tag.

   Unlike the conventional type tag factory, which requires a scala.reflect.api.TypeCreator, this one accepts a regular type, but the resulting type tags are unable of being migrated to other universes/mirrors (the functionality normally not needed for macros, since there is only one compile-time universe and only one compile-time mirror).

   Definition Classes
     Aliases

4. #### abstract def abort(pos: Position, msg: String): Nothing

   Abruptly terminates current macro expansion leaving a note about what happened.

   Abruptly terminates current macro expansion leaving a note about what happened. Use `enclosingPosition` if you're in doubt what position to pass to `pos`.

   Definition Classes
     FrontEnds

5. #### abstract def classPath: List[URL]

   Exposes current classpath.

   Exposes current classpath.

   Definition Classes
     Infrastructure

6. #### abstract def compilerSettings: List[String]

   Exposes current compiler settings as a list of options.

   Exposes current compiler settings as a list of options. Use `scalac -help`, `scalac -X` and `scalac -Y` to learn about currently supported options.

   Definition Classes
     Infrastructure

7. #### abstract def echo(pos: Position, msg: String): Unit

   For sending a message which should not be labeled as a warning/error, but also shouldn't require -verbose to be visible.

   For sending a message which should not be labeled as a warning/error, but also shouldn't require -verbose to be visible. Use `enclosingPosition` if you're in doubt what position to pass to `pos`.

   Definition Classes
     FrontEnds

8. #### abstract val enclosingClass: Tree

   Tree that corresponds to the enclosing class, or EmptyTree if not applicable.

   Tree that corresponds to the enclosing class, or EmptyTree if not applicable.

   Definition Classes
     Enclosures

9. #### abstract val enclosingImplicits: List[(Type, Tree)]

   Information about one of the currently considered implicit candidates.

   Information about one of the currently considered implicit candidates. Candidates are used in plural form, because implicit parameters may themselves have implicit parameters, hence implicit searches can recursively trigger other implicit searches.

   Can be useful to get information about an application with an implicit parameter that is materialized during current macro expansion. If we're in an implicit macro being expanded, it's included in this list.

   Unlike `openImplicits`, this is a val, which means that it gets initialized when the context is created and always stays the same regardless of whatever happens during macro expansion.

   Definition Classes
     Enclosures

10. #### abstract val enclosingMacros: List[Context]

    Contexts that represent macros in-flight, including the current one.

    Contexts that represent macros in-flight, including the current one. Very much like a stack trace, but for macros only. Can be useful for interoperating with other macros and for imposing compiler-friendly limits on macro expansion.

    Is also priceless for emitting sane error messages for macros that are called by other macros on synthetic (i.e. position-less) trees. In that dire case navigate the ``enclosingMacros stack, and it will most likely contain at least one macro with a position-ful macro application. See ``enclosingPosition for a default implementation of this logic.````

    Unlike `openMacros`, this is a val, which means that it gets initialized when the context is created and always stays the same regardless of whatever happens during macro expansion.

    Definition Classes
      Enclosures

11. #### abstract val enclosingMethod: Tree

    Tree that corresponds to the enclosing method, or EmptyTree if not applicable.

    Tree that corresponds to the enclosing method, or EmptyTree if not applicable.

    Definition Classes
      Enclosures

12. #### abstract val enclosingPosition: Position

    Tries to guess a position for the enclosing application.

    Tries to guess a position for the enclosing application. But that is simple, right? Just dereference ``pos of ``macroApplication? Not really. If we're in a synthetic macro expansion (no positions), we must do our best to infer the position of something that triggerd this expansion. Surprisingly, quite often we can do this by navigation the ``enclosingMacros stack.``````

    Definition Classes
      Enclosures

13. #### abstract val enclosingRun: Run

    Compilation run that contains this macro application.

    Compilation run that contains this macro application.

    Definition Classes
      Enclosures

14. #### abstract val enclosingUnit: CompilationUnit

    Compilation unit that contains this macro application.

    Compilation unit that contains this macro application.

    Definition Classes
      Enclosures

15. #### abstract def error(pos: Position, msg: String): Unit

    Emits a compilation error.

    Emits a compilation error. Use `enclosingPosition` if you're in doubt what position to pass to `pos`.

    Definition Classes
      FrontEnds

16. #### abstract def eval[T](expr: Expr[T]): T

    Takes a typed wrapper for a tree of type `T` and evaluates it to a value of type `T`.

    Takes a typed wrapper for a tree of type `T` and evaluates it to a value of type `T`.

    Can be used to perform compile-time computations on macro arguments to the extent permitted by the shape of the arguments.

    Known issues: because of https://issues.scala-lang.org/browse/SI-5748 trees being evaluated first need to undergo `resetAllAttrs`. Resetting symbols and types mutates the tree in place, therefore the conventional approach is to `duplicate` the tree first.

        scala> def impl(c: Context)(x: c.Expr[String]) = {
             | val x1 = c.Expr[String](c.resetAllAttrs(x.tree.duplicate))
             | println(s"compile-time value is: ${c.eval(x1)}")
             | x
             | }
        impl: (c: Context)(x: c.Expr[String])c.Expr[String]

        scala> def test(x: String) = macro impl
        test: (x: String)String

        scala> test("x")
        compile-time value is: x
        res0: String = x

        scala> test("x" + "y")
        compile-time value is: xy
        res1: String = xy

        scala> val x = "x"
        x: String = x

        scala> test(x + "y")
        compile-time value is: xy
        res2: String = xy

        scala> { val x = "x"; test(x + "y") }
        error: exception during macro expansion:
        scala.tools.reflect.ToolBoxError: reflective compilation failed

    Note that in the last case evaluation has failed, because the argument of a macro refers to a runtime value `x`, which is unknown at compile time.

    Definition Classes
      Evals

17. #### abstract def fresh[NameType <: Name](name: NameType): NameType

    Creates a unique name having a given name as a prefix and having the same flavor (term name or type name) as the given name.

    Creates a unique name having a given name as a prefix and having the same flavor (term name or type name) as the given name.

    Definition Classes
      Names

18. #### abstract def fresh(name: String): String

    Creates a unique string having a given prefix.

    Creates a unique string having a given prefix.

    Definition Classes
      Names

19. #### abstract def fresh(): String

    Creates a unique string.

    Creates a unique string.

    Definition Classes
      Names

20. #### abstract def hasErrors: Boolean

    Does the compilation session have any errors?

    Does the compilation session have any errors?

    Definition Classes
      FrontEnds

21. #### abstract def hasWarnings: Boolean

    Does the compilation session have any warnings?

    Does the compilation session have any warnings?

    Definition Classes
      FrontEnds

22. #### abstract def inferImplicitValue(pt: Type, silent: Boolean = true, withMacrosDisabled: Boolean = false, pos: Position = enclosingPosition): Tree

    Infers an implicit value of the expected type `pt` in the macro callsite context.

    Infers an implicit value of the expected type `pt` in the macro callsite context. Optional `pos` parameter provides a position that will be associated with the implicit search.

    If `silent` is false, `TypecheckException` will be thrown in case of an inference error. If `silent` is true, the typecheck is silent and will return `EmptyTree` if an error occurs. Such errors don't vanish and can be inspected by turning on -Xlog-implicits. Unlike in `typeCheck`, `silent` is true by default.

    Definition Classes
      Typers
    Exceptions thrown
      [[scala.reflect.macros.TypecheckException]]

23. #### abstract def inferImplicitView(tree: Tree, from: Type, to: Type, silent: Boolean = true, withMacrosDisabled: Boolean = false, pos: Position = enclosingPosition): Tree

    Infers an implicit view from the provided tree `tree` of the type `from` to the type `to` in the macro callsite context.

    Infers an implicit view from the provided tree `tree` of the type `from` to the type `to` in the macro callsite context. Optional `pos` parameter provides a position that will be associated with the implicit search.

    If `silent` is false, `TypecheckException` will be thrown in case of an inference error. If `silent` is true, the typecheck is silent and will return `EmptyTree` if an error occurs. Such errors don't vanish and can be inspected by turning on -Xlog-implicits. Unlike in `typeCheck`, `silent` is true by default.

    Definition Classes
      Typers
    Exceptions thrown
      [[scala.reflect.macros.TypecheckException]]

24. #### abstract def info(pos: Position, msg: String, force: Boolean): Unit

    Emits an informational message, suppressed unless `-verbose` or `force=true`.

    Emits an informational message, suppressed unless `-verbose` or `force=true`. Use `enclosingPosition` if you're in doubt what position to pass to `pos`.

    Definition Classes
      FrontEnds

25. #### abstract def literal(x: Char): Expr[Char]

    Shorthand for `Literal(Constant(x: Char))` in the underlying `universe`.

    Shorthand for `Literal(Constant(x: Char))` in the underlying `universe`.

    Definition Classes
      ExprUtils

26. #### abstract def literal(x: String): Expr[String]

    Shorthand for `Literal(Constant(x: String))` in the underlying `universe`.

    Shorthand for `Literal(Constant(x: String))` in the underlying `universe`.

    Definition Classes
      ExprUtils

27. #### abstract def literal(x: Double): Expr[Double]

    Shorthand for `Literal(Constant(x: Double))` in the underlying `universe`.

    Shorthand for `Literal(Constant(x: Double))` in the underlying `universe`.

    Definition Classes
      ExprUtils

28. #### abstract def literal(x: Float): Expr[Float]

    Shorthand for `Literal(Constant(x: Float))` in the underlying `universe`.

    Shorthand for `Literal(Constant(x: Float))` in the underlying `universe`.

    Definition Classes
      ExprUtils

29. #### abstract def literal(x: Long): Expr[Long]

    Shorthand for `Literal(Constant(x: Long))` in the underlying `universe`.

    Shorthand for `Literal(Constant(x: Long))` in the underlying `universe`.

    Definition Classes
      ExprUtils

30. #### abstract def literal(x: Int): Expr[Int]

    Shorthand for `Literal(Constant(x: Int))` in the underlying `universe`.

    Shorthand for `Literal(Constant(x: Int))` in the underlying `universe`.

    Definition Classes
      ExprUtils

31. #### abstract def literal(x: Short): Expr[Short]

    Shorthand for `Literal(Constant(x: Short))` in the underlying `universe`.

    Shorthand for `Literal(Constant(x: Short))` in the underlying `universe`.

    Definition Classes
      ExprUtils

32. #### abstract def literal(x: Byte): Expr[Byte]

    Shorthand for `Literal(Constant(x: Byte))` in the underlying `universe`.

    Shorthand for `Literal(Constant(x: Byte))` in the underlying `universe`.

    Definition Classes
      ExprUtils

33. #### abstract def literal(x: Boolean): Expr[Boolean]

    Shorthand for `Literal(Constant(x: Boolean))` in the underlying `universe`.

    Shorthand for `Literal(Constant(x: Boolean))` in the underlying `universe`.

    Definition Classes
      ExprUtils

34. #### abstract def literalFalse: Expr[Boolean]

    Shorthand for `Literal(Constant(false))` in the underlying `universe`.

    Shorthand for `Literal(Constant(false))` in the underlying `universe`.

    Definition Classes
      ExprUtils

35. #### abstract def literalNull: Expr[Null]

    Shorthand for `Literal(Constant(null))` in the underlying `universe`.

    Shorthand for `Literal(Constant(null))` in the underlying `universe`.

    Definition Classes
      ExprUtils

36. #### abstract def literalTrue: Expr[Boolean]

    Shorthand for `Literal(Constant(true))` in the underlying `universe`.

    Shorthand for `Literal(Constant(true))` in the underlying `universe`.

    Definition Classes
      ExprUtils

37. #### abstract def literalUnit: Expr[Unit]

    Shorthand for `Literal(Constant(()))` in the underlying `universe`.

    Shorthand for `Literal(Constant(()))` in the underlying `universe`.

    Definition Classes
      ExprUtils

38. #### abstract val macroApplication: Tree

    The tree that undergoes macro expansion.

    The tree that undergoes macro expansion. Can be useful to get an offset or a range position of the entire tree being processed.

    Definition Classes
      Enclosures

39. #### abstract val mirror: Universe.Mirror

    The mirror of the compile-time universe.

40. #### abstract def openImplicits: List[(Type, Tree)]

    Information about one of the currently considered implicit candidates.

    Information about one of the currently considered implicit candidates. Candidates are used in plural form, because implicit parameters may themselves have implicit parameters, hence implicit searches can recursively trigger other implicit searches.

    Can be useful to get information about an application with an implicit parameter that is materialized during current macro expansion. If we're in an implicit macro being expanded, it's included in this list.

    Unlike `enclosingImplicits`, this is a def, which means that it gets recalculated on every invocation, so it might change depending on what is going on during macro expansion.

    Definition Classes
      Typers

41. #### abstract def openMacros: List[Context]

    Contexts that represent macros in-flight, including the current one.

    Contexts that represent macros in-flight, including the current one. Very much like a stack trace, but for macros only. Can be useful for interoperating with other macros and for imposing compiler-friendly limits on macro expansion.

    Is also priceless for emitting sane error messages for macros that are called by other macros on synthetic (i.e. position-less) trees. In that dire case navigate the `openMacros` stack, and it will most likely contain at least one macro with a position-ful macro application. See `enclosingPosition` for a default implementation of this logic.

    Unlike `enclosingMacros`, this is a def, which means that it gets recalculated on every invocation, so it might change depending on what is going on during macro expansion.

    Definition Classes
      Typers

42. #### abstract def parse(code: String): Tree

    Parses a string with a Scala expression into an abstract syntax tree.

    Parses a string with a Scala expression into an abstract syntax tree. Only works for expressions, i.e. parsing a package declaration will fail.

    Definition Classes
      Parsers
    Exceptions thrown
      [[scala.reflect.macros.ParseException]]

43. #### abstract val prefix: Expr[PrefixType]

    The prefix tree from which the macro is selected.

    The prefix tree from which the macro is selected.

    For a example, for a macro `filter` defined as an instance method on a collection `Coll`, `prefix` represents an equivalent of `this` for normal instance methods:

        scala> class Coll[T] {
             | def filter(p: T => Boolean): Coll[T] = macro M.filter[T]
             | }; object M {
             | def filter[T](c: Context { type PrefixType = Coll[T] })
             |              (p: c.Expr[T => Boolean]): c.Expr[Coll[T]] =
             |   {
             |     println(c.prefix.tree)
             |     c.prefix
             |   }
             | }
        defined class Coll
        defined module Macros

        scala> new Coll[Int]().filter(_ % 2 == 0)
        new Coll[Int]()
        res0: Coll[Int] = ...

        scala> val x = new Coll[String]()
        x: Coll[String] = ...

        scala> x.filter(_ != "")
        $line11.$read.$iw.$iw.$iw.$iw.$iw.$iw.$iw.$iw.$iw.$iw.$iw.$iw.x
        res1 @ 35563b4b: x.type = ...

    Note how the value of `prefix` changes depending on the qualifier of the macro call (i.e. the expression that is at the left-hand side of the dot).

    Another noteworthy thing about the snippet above is the `Context { type PrefixType = Coll[T] }` type that is used to stress that the macro implementation works with prefixes of type `Coll[T]`.

44. #### abstract def reifyEnclosingRuntimeClass: Tree

    Given a type, generate a tree that when compiled and executed produces the runtime class of the enclosing class or module.

    Given a type, generate a tree that when compiled and executed produces the runtime class of the enclosing class or module. Returns `EmptyTree` if there does not exist an enclosing class or module.

    Definition Classes
      Reifiers

45. #### abstract def reifyRuntimeClass(tpe: Type, concrete: Boolean = true): Tree

    Given a type, generate a tree that when compiled and executed produces the runtime class of the original type.

    Given a type, generate a tree that when compiled and executed produces the runtime class of the original type. If ``concrete is true, then this function will bail on types, who refer to abstract types (like `ClassTag` does).``

    Definition Classes
      Reifiers

46. #### abstract def reifyTree(universe: Tree, mirror: Tree, tree: Tree): Tree

    Given a tree, generate a tree that when compiled and executed produces the original tree.

    Given a tree, generate a tree that when compiled and executed produces the original tree. For more information and examples see the documentation for ``Universe.reify.``

    The produced tree will be bound to the specified ``universe and ``mirror. Possible values for ``universe include ``universe.treeBuild.mkRuntimeUniverseRef. Possible values for ``mirror include ``EmptyTree (in that case the reifier will automatically pick an appropriate mirror).````````````

    This function is deeply connected to ``Universe.reify, a macro that reifies arbitrary expressions into runtime trees. They do very similar things (``Universe.reify calls ``Context.reifyTree to implement itself), but they operate on different metalevels (see below).``````

    Let's study the differences between ``Context.reifyTree and ``Universe.reify on an example of using them inside a ``fooMacro macro:``````

    * Since reify itself is a macro, it will be executed when fooMacro is being compiled (metalevel -1) and will produce a tree that when evaluated during macro expansion of fooMacro (metalevel 0) will recreate the input tree.

    This provides a facility analogous to quasi-quoting. Writing "reify{ expr }" will generate an AST that represents expr. Afterwards this AST (or its parts) can be used to construct the return value of fooMacro.

    * reifyTree is evaluated during macro expansion (metalevel 0) and will produce a tree that when evaluated during the runtime of the program (metalevel 1) will recreate the input tree.

    This provides a way to retain certain trees from macro expansion time to be inspected later, in the runtime. For example, DSL authors may find it useful to capture DSL snippets into ASTs that are then processed at runtime in a domain-specific way.

    Also note the difference between universes of the runtime trees produced by two reifies:

    * The result of compiling and running the result of reify will be bound to the Universe that called reify. This is possible because it's a macro, so it can generate whatever code it wishes.

    * The result of compiling and running the result of reifyTree will be the ``prefix that needs to be passed explicitly. This happens because the Universe of the evaluated result is from a different metalevel than the Context the called reify.``

    Typical usage of this function is to retain some of the trees received/created by a macro into the form that can be inspected (via pattern matching) or compiled/run (by a reflective ToolBox) during the runtime.

    Definition Classes
      Reifiers

47. #### abstract def reifyType(universe: Tree, mirror: Tree, tpe: Type, concrete: Boolean = false): Tree

    Given a type, generate a tree that when compiled and executed produces the original type.

    Given a type, generate a tree that when compiled and executed produces the original type. The produced tree will be bound to the specified ``universe and ``mirror. For more information and examples see the documentation for ``Context.reifyTree and ``Universe.reify.````````

    Definition Classes
      Reifiers

48. #### abstract def resetAllAttrs(tree: Tree): Tree

    Recursively resets symbols and types in a given tree.

    Recursively resets symbols and types in a given tree.

    Note that this does not revert the tree to its pre-typer shape. For more info, read up https://issues.scala-lang.org/browse/SI-5464.

    Definition Classes
      Typers

49. #### abstract def resetLocalAttrs(tree: Tree): Tree

    Recursively resets locally defined symbols and types in a given tree.

    Recursively resets locally defined symbols and types in a given tree.

    Note that this does not revert the tree to its pre-typer shape. For more info, read up https://issues.scala-lang.org/browse/SI-5464.

    Definition Classes
      Typers

50. #### abstract def settings: List[String]

    Exposes macro-specific settings as a list of strings.

    Exposes macro-specific settings as a list of strings. These settings are passed to the compiler via the "-Xmacro-settings:setting1,setting2...,settingN" command-line option.

    Definition Classes
      Infrastructure

51. #### abstract def typeCheck(tree: Tree, pt: Type = WildcardType, silent: Boolean = false, withImplicitViewsDisabled: Boolean = false, withMacrosDisabled: Boolean = false): Tree

    Typechecks the provided tree against the expected type `pt` in the macro callsite context.

    Typechecks the provided tree against the expected type `pt` in the macro callsite context.

    If `silent` is false, `TypecheckException` will be thrown in case of a typecheck error. If `silent` is true, the typecheck is silent and will return `EmptyTree` if an error occurs. Such errors don't vanish and can be inspected by turning on -Ymacro-debug-verbose. Unlike in `inferImplicitValue` and `inferImplicitView`, `silent` is false by default.

    Typechecking can be steered with the following optional parameters: `withImplicitViewsDisabled` recursively prohibits implicit views (though, implicit vals will still be looked up and filled in), default value is false `withMacrosDisabled` recursively prohibits macro expansions and macro-based implicits, default value is false

    Definition Classes
      Typers
    Exceptions thrown
      [[scala.reflect.macros.TypecheckException]]

52. #### abstract val universe: Universe

    The compile-time universe.

53. #### abstract def unreifyTree(tree: Tree): Tree

    Undoes reification of a tree.

    Undoes reification of a tree.

    This reversion doesn't simply restore the original tree (that would lose the context of reification), but does something more involved that conforms to the following laws:

    1) unreifyTree(reifyTree(tree)) != tree // unreified tree is tree + saved context // in current implementation, the result of unreify is opaque // i.e. there's no possibility to inspect underlying tree/context

    2) reifyTree(unreifyTree(reifyTree(tree))) == reifyTree(tree) // the result of reifying a tree in its original context equals to // the result of reifying a tree along with its saved context

    3) compileAndEval(unreifyTree(reifyTree(tree))) ~ compileAndEval(tree) // at runtime original and unreified trees are behaviorally equivalent

    Definition Classes
      Reifiers

54. #### abstract def warning(pos: Position, msg: String): Unit

    Emits a warning.

    Emits a warning. Use `enclosingPosition` if you're in doubt what position to pass to `pos`.

    Definition Classes
      FrontEnds

### Concrete Value Members

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

   Definition Classes
     AnyRef

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

   Test two objects for inequality.

   Test two objects for inequality.

   returns

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

   Definition Classes
     Any

3. #### 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

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

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

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

   Implicit information
     This member is added by an implicit conversion from Context to ArrowAssoc[Context] performed by method any2ArrowAssoc in scala.Predef.
   Definition Classes
     ArrowAssoc
   Annotations
     @inline ()

6. #### final def ==(arg0: AnyRef): Boolean

   Definition Classes
     AnyRef

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

   Test two objects for equality.

   Test two objects for equality. 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
     Any

8. #### val Expr: Universe.Expr.type

   Constructor/Extractor for `Expr`.

   Constructor/Extractor for `Expr`.

   Definition Classes
     Aliases

9. #### val TypeTag: Universe.TypeTag.type

   Constructor/Extractor for `TypeTag`.

   Constructor/Extractor for `TypeTag`.

   Definition Classes
     Aliases

10. #### val WeakTypeTag: Universe.WeakTypeTag.type

    Constructor/Extractor for `WeakTypeTag`.

    Constructor/Extractor for `WeakTypeTag`.

    Definition Classes
      Aliases

11. #### 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`.

12. #### 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

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

    Implicit information
      This member is added by an implicit conversion from Context to Ensuring[Context] performed by method any2Ensuring in scala.Predef.
    Definition Classes
      Ensuring

14. #### def ensuring(cond: (Context) ⇒ Boolean): Context

    Implicit information
      This member is added by an implicit conversion from Context to Ensuring[Context] performed by method any2Ensuring in scala.Predef.
    Definition Classes
      Ensuring

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

    Implicit information
      This member is added by an implicit conversion from Context to Ensuring[Context] performed by method any2Ensuring in scala.Predef.
    Definition Classes
      Ensuring

16. #### def ensuring(cond: Boolean): Context

    Implicit information
      This member is added by an implicit conversion from Context to Ensuring[Context] performed by method any2Ensuring in scala.Predef.
    Definition Classes
      Ensuring

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

    Tests whether the argument (`arg0`) is a reference to the receiver object (`this`).

    Tests whether the argument (`arg0`) 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

18. #### 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

19. #### 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

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

    Returns string formatted according to given `format` string.

    Returns string formatted according to given `format` string. Format strings are as for `String.format` (@see java.lang.String.format).

    Implicit information
      This member is added by an implicit conversion from Context to StringFormat performed by method any2stringfmt in scala.Predef.
    Definition Classes
      StringFormat
    Annotations
      @inline ()

21. #### 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

22. #### 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

23. #### 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

24. #### 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

25. #### 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

26. #### 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

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

    Definition Classes
      AnyRef

28. #### 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

29. #### def typeOf[T](implicit ttag: TypeTag[T]): Type

    Shortcut for `implicitly[TypeTag[T]].tpe`

    Shortcut for `implicitly[TypeTag[T]].tpe`

    Definition Classes
      Aliases

30. #### def typeTag[T](implicit ttag: TypeTag[T]): TypeTag[T]

    Shortcut for `implicitly[TypeTag[T]]`

    Shortcut for `implicitly[TypeTag[T]]`

    Definition Classes
      Aliases

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

    Definition Classes
      AnyRef
    Annotations
      @throws ( ... )

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

    Definition Classes
      AnyRef
    Annotations
      @throws ( ... )

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

    Definition Classes
      AnyRef
    Annotations
      @throws ( ... )

34. #### def weakTypeOf[T](implicit attag: WeakTypeTag[T]): Type

    Shortcut for `implicitly[WeakTypeTag[T]].tpe`

    Shortcut for `implicitly[WeakTypeTag[T]].tpe`

    Definition Classes
      Aliases

35. #### def weakTypeTag[T](implicit attag: WeakTypeTag[T]): WeakTypeTag[T]

    Shortcut for `implicitly[WeakTypeTag[T]]`

    Shortcut for `implicitly[WeakTypeTag[T]]`

    Definition Classes
      Aliases

36. #### def →[B](y: B): (Context, B)

    Implicit information
      This member is added by an implicit conversion from Context to ArrowAssoc[Context] performed by method any2ArrowAssoc in scala.Predef.
    Definition Classes
      ArrowAssoc

### Shadowed Implicit Value Members

1. #### val self: Any

   Implicit information
     This member is added by an implicit conversion from Context to StringAdd performed by method any2stringadd in scala.Predef.
   Shadowing
     This implicitly inherited member is ambiguous. One or more implicitly inherited members have similar signatures, so calling this member may produce an ambiguous implicit conversion compiler error.
     To access this member you can use a type ascription:

         (context: StringAdd).self

   Definition Classes
     StringAdd

2. #### val self: Any

   Implicit information
     This member is added by an implicit conversion from Context to StringFormat performed by method any2stringfmt in scala.Predef.
   Shadowing
     This implicitly inherited member is ambiguous. One or more implicitly inherited members have similar signatures, so calling this member may produce an ambiguous implicit conversion compiler error.
     To access this member you can use a type ascription:

         (context: StringFormat).self

   Definition Classes
     StringFormat

### Deprecated Value Members

1. #### def x: Context

   Implicit information
     This member is added by an implicit conversion from Context to ArrowAssoc[Context] performed by method any2ArrowAssoc in scala.Predef.
   Shadowing
     This implicitly inherited member is ambiguous. One or more implicitly inherited members have similar signatures, so calling this member may produce an ambiguous implicit conversion compiler error.
     To access this member you can use a type ascription:

         (context: ArrowAssoc[Context]).x

   Definition Classes
     ArrowAssoc
   Annotations
     @deprecated
   Deprecated

     (Since version 2.10.0) Use `leftOfArrow`instead``

2. #### def x: Context

   Implicit information
     This member is added by an implicit conversion from Context to Ensuring[Context] performed by method any2Ensuring in scala.Predef.
   Shadowing
     This implicitly inherited member is ambiguous. One or more implicitly inherited members have similar signatures, so calling this member may produce an ambiguous implicit conversion compiler error.
     To access this member you can use a type ascription:

         (context: Ensuring[Context]).x

   Definition Classes
     Ensuring
   Annotations
     @deprecated
   Deprecated

     (Since version 2.10.0) Use `resultOfEnsuring`instead``

### Inherited from ExprUtils

### Inherited from Evals

### Inherited from Parsers

### Inherited from Typers

### Inherited from Infrastructure

### Inherited from FrontEnds

### Inherited from Reifiers

### Inherited from Names

### Inherited from Enclosures

### Inherited from Aliases

### Inherited from AnyRef

### Inherited from Any

### Inherited by implicit conversion any2stringadd from Context to StringAdd

### Inherited by implicit conversion any2stringfmt from Context to StringFormat

### Inherited by implicit conversion any2ArrowAssoc from Context to ArrowAssoc[Context]

### Inherited by implicit conversion any2Ensuring from Context to Ensuring[Context]

### Ungrouped