ElimByName

dotty.tools.dotc.transform.ElimByName
See theElimByName companion object

This phase implements the following transformations:

  1. For types of method and class parameters:

    => T becomes () ?=> T

  2. For references to cbn-parameters:

    x becomes x.apply()

  3. For arguments to cbn parameters

    e becomes () ?=> e

An optimization is applied: If the argument e to a cbn parameter is already of type () ?=> T and is a pure expression, we avoid (2) and (3), i.e. we pass e directly instead of () ?=> e.apply().

Note that () ?=> T cannot be written in source since user-defined context functions must have at least one parameter. We use the type here as a convenient marker of something that will erase to Function0, and where we know that it came from a by-name parameter.

Note also that the transformation applies only to types of parameters, not to other occurrences of ExprTypes. In particular, embedded occurrences in function types such as (=> T) => U are left as-is here (they are eliminated in erasure). Trying to convert these as well would mean traversing all the types, and that leads to cyclic reference errors in many cases. This can cause problems in that we might have sometimes a () ?=> T where a => T is expected. To compensate, there is a new clause in TypeComparer#subArg that declares () ?=> T to be a subtype of => T for arguments of type applications at any point after this phase and up to erasure.

Attributes

Companion
object
Graph
Supertypes
class MiniPhase
class Phase
class Object
trait Matchable
class Any
Show all
Self type

Members list

Value members

Concrete methods

def byNameClosure(arg: Tree, argType: Type)(using Context): Tree
override def changesParents: Boolean

Can this transform change the parents of a class?

Can this transform change the parents of a class?

Attributes

Definition Classes
override def description: String

Attributes

Definition Classes
override def infoMayChange(sym: Symbol)(using Context): Boolean

Denotations with a symbol where infoMayChange is false are guaranteed to be unaffected by this transform, so transformInfo need not be run. This can save time, and more importantly, can help avoid forcing symbol completers.

Denotations with a symbol where infoMayChange is false are guaranteed to be unaffected by this transform, so transformInfo need not be run. This can save time, and more importantly, can help avoid forcing symbol completers.

Attributes

Definition Classes
override def phaseName: String

A name given to the Phase that can be used to debug the compiler. For instance, it is possible to print trees after a given phase using:

A name given to the Phase that can be used to debug the compiler. For instance, it is possible to print trees after a given phase using:

$ ./bin/scalac -Xprint:<phaseNameHere> sourceFile.scala

Attributes

Definition Classes
override def runsAfterGroupsOf: Set[String]

List of names of phases that should have finished their processing of all compilation units before this phase starts

List of names of phases that should have finished their processing of all compilation units before this phase starts

Attributes

Definition Classes
override def transformApply(tree: Apply)(using Context): Tree

Attributes

Definition Classes
override def transformIdent(tree: Ident)(using Context): Tree

Attributes

Definition Classes
def transformInfo(tp: Type, sym: Symbol)(using Context): Type
override def transformSelect(tree: Select)(using Context): Tree

Attributes

Definition Classes
override def transformTypeApply(tree: TypeApply)(using Context): Tree

Attributes

Definition Classes
override def transformValDef(tree: ValDef)(using Context): Tree

Attributes

Definition Classes

Inherited methods

final def <=(that: Phase): Boolean

Attributes

Inherited from:
Phase

If set, implicit search is enabled

If set, implicit search is enabled

Attributes

Inherited from:
Phase

Can this transform change the base types of a type?

Can this transform change the base types of a type?

Attributes

Inherited from:
Phase

Can this transform create or delete non-private members?

Can this transform create or delete non-private members?

Attributes

Inherited from:
Phase
def checkPostCondition(tree: Tree)(using Context): Unit

Check what the phase achieves, to be called at any point after it is finished.

Check what the phase achieves, to be called at any point after it is finished.

Attributes

Inherited from:
Phase
def end: PhaseId

Attributes

Inherited from:
Phase
final def erasedTypes: Boolean

Attributes

Inherited from:
Phase

Attributes

Inherited from:
Phase
final def flatClasses: Boolean

Attributes

Inherited from:
Phase
final def hasNext: Boolean

Attributes

Inherited from:
Phase
def id: Int

The sequence position of this phase in the given context where 0 is reserved for NoPhase and the first real phase is at position 1. -1 if the phase is not installed in the context.

The sequence position of this phase in the given context where 0 is reserved for NoPhase and the first real phase is at position 1. -1 if the phase is not installed in the context.

Attributes

Inherited from:
Phase

Attributes

Inherited from:
Phase

Output should be checkable by TreeChecker

Output should be checkable by TreeChecker

Attributes

Inherited from:
Phase
def isEnabled(using Context): Boolean

Attributes

Inherited from:
Phase
def isRunnable(using Context): Boolean

Attributes

Inherited from:
Phase

Is this phase the standard typerphase? True for TyperPhase, but not for other first phases (such as FromTasty or Parser). The predicate is tested in some places that perform checks and corrections. It's different from ctx.isAfterTyper (and cheaper to test).

Is this phase the standard typerphase? True for TyperPhase, but not for other first phases (such as FromTasty or Parser). The predicate is tested in some places that perform checks and corrections. It's different from ctx.isAfterTyper (and cheaper to test).

Attributes

Inherited from:
Phase
final def iterator: Iterator[Phase]

Attributes

Inherited from:
Phase
final def lambdaLifted: Boolean

Attributes

Inherited from:
Phase
def lastPhaseId(using Context): Int

The last phase during which the transformed denotations are valid

The last phase during which the transformed denotations are valid

Attributes

Inherited from:
DenotTransformer
final def megaPhase(using Context): Phase

Attributes

Inherited from:
Phase
final def monitor(doing: String)(body: => Unit)(using Context): Unit

Attributes

Inherited from:
Phase
final def next: Phase

Attributes

Inherited from:
Phase

Attributes

Inherited from:
Phase
def period: Period

Attributes

Inherited from:
Phase

Attributes

Inherited from:
MiniPhase
def prepareForApply(tree: Apply)(using Context): Context

Attributes

Inherited from:
MiniPhase
def prepareForAssign(tree: Assign)(using Context): Context

Attributes

Inherited from:
MiniPhase
def prepareForBind(tree: Bind)(using Context): Context

Attributes

Inherited from:
MiniPhase
def prepareForBlock(tree: Block)(using Context): Context

Attributes

Inherited from:
MiniPhase

Attributes

Inherited from:
MiniPhase

Attributes

Inherited from:
MiniPhase
def prepareForDefDef(tree: DefDef)(using Context): Context

Attributes

Inherited from:
MiniPhase
def prepareForIdent(tree: Ident)(using Context): Context

Attributes

Inherited from:
MiniPhase
def prepareForIf(tree: If)(using Context): Context

Attributes

Inherited from:
MiniPhase

Attributes

Inherited from:
MiniPhase

Attributes

Inherited from:
MiniPhase

Attributes

Inherited from:
MiniPhase
def prepareForMatch(tree: Match)(using Context): Context

Attributes

Inherited from:
MiniPhase
def prepareForNew(tree: New)(using Context): Context

Attributes

Inherited from:
MiniPhase
def prepareForOther(tree: Tree)(using Context): Context

Attributes

Inherited from:
MiniPhase

Attributes

Inherited from:
MiniPhase
def prepareForQuote(tree: Quote)(using Context): Context

Attributes

Inherited from:
MiniPhase
def prepareForReturn(tree: Return)(using Context): Context

Attributes

Inherited from:
MiniPhase
def prepareForSelect(tree: Select)(using Context): Context

Attributes

Inherited from:
MiniPhase

Attributes

Inherited from:
MiniPhase
def prepareForSplice(tree: Splice)(using Context): Context

Attributes

Inherited from:
MiniPhase
def prepareForStats(trees: List[Tree])(using Context): Context

Attributes

Inherited from:
MiniPhase
def prepareForSuper(tree: Super)(using Context): Context

Attributes

Inherited from:
MiniPhase

Attributes

Inherited from:
MiniPhase
def prepareForThis(tree: This)(using Context): Context

Attributes

Inherited from:
MiniPhase
def prepareForTry(tree: Try)(using Context): Context

Attributes

Inherited from:
MiniPhase

Attributes

Inherited from:
MiniPhase

Attributes

Inherited from:
MiniPhase

Attributes

Inherited from:
MiniPhase
def prepareForTyped(tree: Typed)(using Context): Context

Attributes

Inherited from:
MiniPhase

Attributes

Inherited from:
MiniPhase
def prepareForUnit(tree: Tree)(using Context): Context

Attributes

Inherited from:
MiniPhase
def prepareForValDef(tree: ValDef)(using Context): Context

Attributes

Inherited from:
MiniPhase

Attributes

Inherited from:
MiniPhase
final def prev: Phase

Attributes

Inherited from:
Phase

A hook that allows to transform the usual context passed to the function that prints a compilation unit after a phase

A hook that allows to transform the usual context passed to the function that prints a compilation unit after a phase

Attributes

Inherited from:
Phase
final def refChecked: Boolean

Attributes

Inherited from:
Phase
final override def relaxedTyping: Boolean

If set, allow missing or superfluous arguments in applications and type applications.

If set, allow missing or superfluous arguments in applications and type applications.

Attributes

Definition Classes
Inherited from:
MiniPhase

If set, use relaxed typing for all phases in group

If set, use relaxed typing for all phases in group

Attributes

Inherited from:
MiniPhase
override def run(using Context): Unit

Attributes

Definition Classes
Inherited from:
MiniPhase
def runOn(units: List[CompilationUnit])(using runCtx: Context): List[CompilationUnit]

Attributes

Inherited from:
Phase

List of names of phases that should precede this phase

List of names of phases that should precede this phase

Attributes

Inherited from:
Phase

Attributes

Inherited from:
Phase
final def sameMembersStartId: Int

Attributes

Inherited from:
Phase
final def sameParentsStartId: Int

Attributes

Inherited from:
Phase
def show(tree: Tree)(using Context): String

Convert a compilation unit's tree to a string; can be overridden

Convert a compilation unit's tree to a string; can be overridden

Attributes

Inherited from:
Phase
protected def singletonGroup: MegaPhase

Attributes

Inherited from:
MiniPhase
def start: Int

Attributes

Inherited from:
Phase
override def toString: String

Returns a string representation of the object.

Returns a string representation of the object.

The default representation is platform dependent.

Attributes

Returns

a string representation of the object.

Definition Classes
Phase -> Any
Inherited from:
Phase

The transformation method

The transformation method

Attributes

Inherited from:
InfoTransformer
def transformAllDeep(tree: Tree)(using Context): Tree

Transform tree using all transforms of current group (including this one)

Transform tree using all transforms of current group (including this one)

Attributes

Inherited from:
MiniPhase

Attributes

Inherited from:
MiniPhase
def transformAssign(tree: Assign)(using Context): Tree

Attributes

Inherited from:
MiniPhase
def transformBind(tree: Bind)(using Context): Tree

Attributes

Inherited from:
MiniPhase
def transformBlock(tree: Block)(using Context): Tree

Attributes

Inherited from:
MiniPhase
def transformCaseDef(tree: CaseDef)(using Context): Tree

Attributes

Inherited from:
MiniPhase
def transformClosure(tree: Closure)(using Context): Tree

Attributes

Inherited from:
MiniPhase
def transformDefDef(tree: DefDef)(using Context): Tree

Attributes

Inherited from:
MiniPhase
def transformFollowing(tree: Tree)(using Context): Tree

Transform single node using all transforms following the current one in this group

Transform single node using all transforms following the current one in this group

Attributes

Inherited from:
MiniPhase

Transform tree using all transforms following the current one in this group

Transform tree using all transforms following the current one in this group

Attributes

Inherited from:
MiniPhase
def transformIf(tree: If)(using Context): Tree

Attributes

Inherited from:
MiniPhase
def transformInlined(tree: Inlined)(using Context): Tree

Attributes

Inherited from:
MiniPhase
def transformLabeled(tree: Labeled)(using Context): Tree

Attributes

Inherited from:
MiniPhase
def transformLiteral(tree: Literal)(using Context): Tree

Attributes

Inherited from:
MiniPhase
def transformMatch(tree: Match)(using Context): Tree

Attributes

Inherited from:
MiniPhase
def transformNew(tree: New)(using Context): Tree

Attributes

Inherited from:
MiniPhase
def transformOther(tree: Tree)(using Context): Tree

Attributes

Inherited from:
MiniPhase

Attributes

Inherited from:
MiniPhase
def transformQuote(tree: Quote)(using Context): Tree

Attributes

Inherited from:
MiniPhase
def transformReturn(tree: Return)(using Context): Tree

Attributes

Inherited from:
MiniPhase

Attributes

Inherited from:
MiniPhase
def transformSplice(tree: Splice)(using Context): Tree

Attributes

Inherited from:
MiniPhase
def transformStats(trees: List[Tree])(using Context): List[Tree]

Attributes

Inherited from:
MiniPhase
def transformSuper(tree: Super)(using Context): Tree

Attributes

Inherited from:
MiniPhase
def transformTemplate(tree: Template)(using Context): Tree

Attributes

Inherited from:
MiniPhase
def transformThis(tree: This)(using Context): Tree

Attributes

Inherited from:
MiniPhase
def transformTry(tree: Try)(using Context): Tree

Attributes

Inherited from:
MiniPhase
def transformTypeDef(tree: TypeDef)(using Context): Tree

Attributes

Inherited from:
MiniPhase
def transformTypeTree(tree: TypeTree)(using Context): Tree

Attributes

Inherited from:
MiniPhase
def transformTyped(tree: Typed)(using Context): Tree

Attributes

Inherited from:
MiniPhase
def transformUnApply(tree: UnApply)(using Context): Tree

Attributes

Inherited from:
MiniPhase
def transformUnit(tree: Tree)(using Context): Tree

Attributes

Inherited from:
MiniPhase
def transformWhileDo(tree: WhileDo)(using Context): Tree

Attributes

Inherited from:
MiniPhase
def validFor(using Context): Period

The validity period of the transformed denotations in the given context

The validity period of the transformed denotations in the given context

Attributes

Inherited from:
DenotTransformer

Inherited fields

Attributes

Inherited from:
MiniPhase