/
Typers.scala
6355 lines (5737 loc) · 309 KB
/
Typers.scala
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/*
* Scala (https://www.scala-lang.org)
*
* Copyright EPFL and Lightbend, Inc.
*
* Licensed under Apache License 2.0
* (http://www.apache.org/licenses/LICENSE-2.0).
*
* See the NOTICE file distributed with this work for
* additional information regarding copyright ownership.
*/
package scala
package tools.nsc
package typechecker
import scala.annotation.{nowarn, tailrec}
import scala.collection.mutable
import scala.reflect.internal.{Chars, TypesStats}
import scala.reflect.internal.util.{FreshNameCreator, ListOfNil, Statistics, StatisticsStatics}
import scala.tools.nsc.Reporting.{MessageFilter, Suppression, WConf, WarningCategory}
import scala.util.chaining._
import mutable.ListBuffer
import symtab.Flags._
import Mode._
/** A provider of methods to assign types to trees.
*
* @author Martin Odersky
*/
trait Typers extends Adaptations with Tags with TypersTracking with PatternTypers {
self: Analyzer =>
import global._
import definitions._
import statistics._
final def forArgMode(fun: Tree, mode: Mode) =
if (treeInfo.isSelfOrSuperConstrCall(fun)) mode | SCCmode else mode
final val shortenImports = false
// All typechecked RHS of ValDefs for right-associative operator desugaring
private val rightAssocValDefs = new mutable.AnyRefMap[Symbol, Tree]
// Symbols of ValDefs for right-associative operator desugaring which are passed by name and have been inlined
private val inlinedRightAssocValDefs = new mutable.HashSet[Symbol]
// For each class, we collect a mapping from constructor param accessors that are aliases of their superclass
// param accessors. At the end of the typer phase, when this information is available all the way up the superclass
// chain, this is used to determine which are true aliases, ones where the field can be elided from this class.
// And yes, if you were asking, this is yet another binary fragility, as we bake knowledge of the super class into
// this class.
private val superConstructorCalls: mutable.AnyRefMap[Symbol, collection.Map[Symbol, Symbol]] = perRunCaches.newAnyRefMap()
// allows override of the behavior of the resetTyper method w.r.t comments
def resetDocComments() = clearDocComments()
def resetTyper(): Unit = {
//println("resetTyper called")
resetContexts()
resetImplicits()
resetDocComments()
rightAssocValDefs.clear()
inlinedRightAssocValDefs.clear()
superConstructorCalls.clear()
}
sealed abstract class SilentResult[+T] {
def isEmpty: Boolean
def nonEmpty = !isEmpty
@inline final def fold[U](none: => U)(f: T => U): U = this match {
case SilentResultValue(value) => f(value)
case _ => none
}
@inline final def map[U](f: T => U): SilentResult[U] = this match {
case SilentResultValue(value) => SilentResultValue(f(value))
case x: SilentTypeError => x
}
@inline final def filter(p: T => Boolean): SilentResult[T] = this match {
case SilentResultValue(value) if !p(value) => SilentTypeError(TypeErrorWrapper(new TypeError(NoPosition, "!p")))
case _ => this
}
@inline final def orElse[T1 >: T](f: Seq[AbsTypeError] => T1): T1 = this match {
case SilentResultValue(value) => value
case s : SilentTypeError => f(s.reportableErrors)
}
}
class SilentTypeError private(val errors: List[AbsTypeError], val warnings: List[(Position, String, WarningCategory, Symbol)]) extends SilentResult[Nothing] {
override def isEmpty = true
def err: AbsTypeError = errors.head
def reportableErrors = errors match {
case (e1: AmbiguousImplicitTypeError) :: _ =>
List(e1) // DRYer error reporting for neg/t6436b.scala
case all =>
all
}
}
object SilentTypeError {
def apply(errors: AbsTypeError*): SilentTypeError = apply(errors.toList, Nil)
def apply(errors: List[AbsTypeError], warnings: List[(Position, String, WarningCategory, Symbol)]): SilentTypeError = new SilentTypeError(errors, warnings)
// todo: this extracts only one error, should be a separate extractor.
def unapply(error: SilentTypeError): Option[AbsTypeError] = error.errors.headOption
}
// todo: should include reporter warnings in SilentResultValue.
// e.g. tryTypedApply could print warnings on arguments when the typing succeeds.
case class SilentResultValue[+T](value: T) extends SilentResult[T] { override def isEmpty = false }
def newTyper(context: Context): Typer = new NormalTyper(context)
private class NormalTyper(context : Context) extends Typer(context)
// A transient flag to mark members of anonymous classes
// that are turned private by typedBlock
private final val SYNTHETIC_PRIVATE = TRANS_FLAG
private final val InterpolatorCodeRegex = """\$\{\s*(.*?)\s*\}""".r
private final val InterpolatorIdentRegex = """\$[$\w]+""".r // note that \w doesn't include $
/** Check that type of given tree does not contain local or private
* components.
*/
object checkNoEscaping extends TypeMap {
private var owner: Symbol = _
private var scope: Scope = _
private var hiddenSymbols: List[Symbol] = _
/** Check that type `tree` does not refer to private
* components unless itself is wrapped in something private
* (`owner` tells where the type occurs).
*/
def privates[T <: Tree](typer: Typer, owner: Symbol, tree: T): T =
if (owner.isJavaDefined) tree else check(typer, owner, EmptyScope, WildcardType, tree)
@tailrec
private def check[T <: Tree](typer: Typer, owner: Symbol, scope: Scope, pt: Type, tree: T): T = {
this.owner = owner
this.scope = scope
hiddenSymbols = Nil
import typer.TyperErrorGen._
val tp1 = apply(tree.tpe)
if (hiddenSymbols.isEmpty) tree setType tp1
else if (hiddenSymbols exists (_.isErroneous)) HiddenSymbolWithError(tree)
else if (isFullyDefined(pt)) tree setType pt
else if (tp1.typeSymbol.isAnonymousClass)
check(typer, owner, scope, pt, tree setType tp1.typeSymbol.classBound)
else if (owner == NoSymbol)
tree setType packSymbols(hiddenSymbols.reverse, tp1)
else if (!isPastTyper) { // privates
val badSymbol = hiddenSymbols.head
SymbolEscapesScopeError(tree, badSymbol)
} else tree
}
def addHidden(sym: Symbol) =
if (!(hiddenSymbols contains sym)) hiddenSymbols = sym :: hiddenSymbols
override def apply(t: Type): Type = {
def checkNoEscape(sym: Symbol): Unit = {
if (sym.isPrivate && !sym.hasFlag(SYNTHETIC_PRIVATE)) {
var o = owner
while (o != NoSymbol && o != sym.owner && o != sym.owner.linkedClassOfClass &&
!o.isLocalToBlock && !o.isPrivate &&
!o.privateWithin.hasTransOwner(sym.owner))
o = o.owner
if (o == sym.owner || o == sym.owner.linkedClassOfClass)
addHidden(sym)
} else if (sym.owner.isTerm && !sym.isTypeParameterOrSkolem) {
var e = scope.lookupEntry(sym.name)
var found = false
while (!found && (e ne null) && e.owner == scope) {
if (e.sym == sym) {
found = true
addHidden(sym)
} else {
e = scope.lookupNextEntry(e)
}
}
}
}
mapOver(
t match {
case TypeRef(_, sym, args) =>
checkNoEscape(sym)
if (!hiddenSymbols.isEmpty && hiddenSymbols.head == sym &&
sym.isAliasType && sameLength(sym.typeParams, args)) {
hiddenSymbols = hiddenSymbols.tail
t.dealias
} else t
case SingleType(_, sym) =>
checkNoEscape(sym)
t
case _ =>
t
})
}
}
private final val typerFreshNameCreators = perRunCaches.newAnyRefMap[Symbol, FreshNameCreator]()
def freshNameCreatorFor(context: Context) = typerFreshNameCreators.getOrElseUpdate(context.outermostContextAtCurrentPos.enclClassOrMethod.owner, new FreshNameCreator)
abstract class Typer(context0: Context) extends TyperDiagnostics with Adaptation with Tag with PatternTyper with TyperContextErrors {
private def unit = context.unit
import typeDebug.ptTree
import TyperErrorGen._
implicit def fresh: FreshNameCreator = freshNameCreatorFor(context)
private def transformed: mutable.Map[Tree, Tree] = unit.transformed
val infer = new Inferencer {
def context = Typer.this.context
// See scala/bug#3281 re undoLog
override def isCoercible(tp: Type, pt: Type) = undoLog undo viewExists(tp, pt)
}
/** Overridden to false in scaladoc and/or interactive. */
def canAdaptConstantTypeToLiteral = true
def canTranslateEmptyListToNil = true
def missingSelectErrorTree(tree: Tree, qual: Tree, name: Name): Tree = tree
// used to exempt synthetic accessors (i.e. those that are synthesized by the compiler to access a field)
// from skolemization because there's a weird bug that causes spurious type mismatches
// (it seems to have something to do with existential abstraction over values
// https://github.com/scala/scala-dev/issues/165
// when we're past typer, lazy accessors are synthetic, but before they are user-defined
// to make this hack less hacky, we could rework our flag assignment to allow for
// requiring both the ACCESSOR and the SYNTHETIC bits to trigger the exemption
private def isSyntheticAccessor(sym: Symbol) = sym.isAccessor && (!sym.isLazy || isPastTyper)
// when type checking during erasure, generate erased types in spots that aren't transformed by erasure
// (it erases in TypeTrees, but not in, e.g., the type a Function node)
def phasedAppliedType(sym: Symbol, args: List[Type]) = {
val tp = appliedType(sym, args)
if (phase.erasedTypes) erasure.specialScalaErasure(tp) else tp
}
def typedDocDef(docDef: DocDef, mode: Mode, pt: Type): Tree =
typed(docDef.definition, mode, pt)
/** Find implicit arguments and pass them to given tree.
*/
def applyImplicitArgs(fun: Tree): Tree = fun.tpe match {
case MethodType(params, _) =>
val argResultsBuff = new ListBuffer[SearchResult]()
val argBuff = new ListBuffer[Tree]()
// paramFailed cannot be initialized with params.exists(_.tpe.isError) because that would
// hide some valid errors for params preceding the erroneous one.
var paramFailed = false
var mkArg: (Name, Tree) => Tree = (_, tree) => tree
// DEPMETTODO: instantiate type vars that depend on earlier implicit args (see adapt (4.1))
//
// apply the substitutions (undet type param -> type) that were determined
// by implicit resolution of implicit arguments on the left of this argument
for(param <- params) {
var paramTp = param.tpe
for(ar <- argResultsBuff)
paramTp = paramTp.subst(ar.subst.from, ar.subst.to)
val res =
if (paramFailed || (paramTp.isErroneous && {paramFailed = true; true})) SearchFailure
else inferImplicitFor(paramTp, fun, context, reportAmbiguous = context.reportErrors)
argResultsBuff += res
if (res.isSuccess) {
argBuff += mkArg(param.name, res.tree)
} else {
mkArg = gen.mkNamedArg // don't pass the default argument (if any) here, but start emitting named arguments for the following args
if (!param.hasDefault && !paramFailed) {
context.reporter.reportFirstDivergentError(fun, param, paramTp)(context)
paramFailed = true
}
/* else {
TODO: alternative (to expose implicit search failure more) -->
resolve argument, do type inference, keep emitting positional args, infer type params based on default value for arg
for (ar <- argResultsBuff) ar.subst traverse defaultVal
val targs = exprTypeArgs(context.undetparams, defaultVal.tpe, paramTp)
substExpr(tree, tparams, targs, pt)
}*/
}
}
val args = argBuff.toList
for (ar <- argResultsBuff) {
ar.subst traverse fun
for (arg <- args) ar.subst traverse arg
}
new ApplyToImplicitArgs(fun, args) setPos fun.pos
case ErrorType =>
fun
case x => throw new MatchError(x)
}
def viewExists(from: Type, to: Type): Boolean = (
!from.isError
&& !to.isError
&& context.implicitsEnabled
&& (inferView(context.tree, from, to, reportAmbiguous = false) != EmptyTree)
// scala/bug#8230 / scala/bug#8463 We'd like to change this to `saveErrors = false`, but can't.
// For now, we can at least pass in `context.tree` rather then `EmptyTree` so as
// to avoid unpositioned type errors.
)
// Get rid of any special ProtoTypes, so that implicit search won't have to deal with them
private def normalizeProtoForView(proto: Type): Type = proto match {
case proto: OverloadedArgProto => proto.underlying
case pt => pt
}
/** Infer an implicit conversion (`view`) between two types.
* @param tree The tree which needs to be converted.
* @param from The source type of the conversion
* @param to The target type of the conversion
* @param reportAmbiguous Should ambiguous implicit errors be reported?
* False iff we search for a view to find out
* whether one type is coercible to another.
* @param saveErrors Should ambiguous and divergent implicit errors that were buffered
* during the inference of a view be put into the original buffer.
* False iff we don't care about them.
*/
def inferView(tree: Tree, from: Type, to: Type, reportAmbiguous: Boolean = true, saveErrors: Boolean = true): Tree =
if (isPastTyper || from.isInstanceOf[MethodType] || from.isInstanceOf[OverloadedType] || from.isInstanceOf[PolyType]) EmptyTree
else {
debuglog(s"Inferring view from $from to $to for $tree (reportAmbiguous= $reportAmbiguous, saveErrors=$saveErrors)")
val fromNoAnnot = from.withoutAnnotations
val toNorm = normalizeProtoForView(to)
val result = inferImplicitView(fromNoAnnot, toNorm, tree, context, reportAmbiguous, saveErrors) match {
case fail if fail.isFailure => inferImplicitView(byNameType(fromNoAnnot), toNorm, tree, context, reportAmbiguous, saveErrors)
case ok => ok
}
if (result.subst != EmptyTreeTypeSubstituter) {
result.subst traverse tree
notifyUndetparamsInferred(result.subst.from, result.subst.to)
}
result.tree
}
import infer._
private var namerCache: Namer = null
def namer: Namer = {
if ((namerCache eq null) || namerCache.context != context)
namerCache = newNamer(context)
namerCache
}
var context = context0
def context1 = context
def dropExistential(tp: Type): Type = tp match {
case ExistentialType(tparams, _) =>
new SubstWildcardMap(tparams).apply(tp)
case TypeRef(_, sym, _) if sym.isAliasType =>
val tp0 = tp.dealias
if (tp eq tp0) {
devWarning(s"dropExistential did not progress dealiasing $tp, see scala/bug#7126")
tp
} else {
val tp1 = dropExistential(tp0)
if (tp1 eq tp0) tp else tp1
}
case _ => tp
}
private def errorNotClass(tpt: Tree, found: Type) = { ClassTypeRequiredError(tpt, found); false }
private def errorNotStable(tpt: Tree, found: Type) = { TypeNotAStablePrefixError(tpt, found); false }
/** Check that `tpt` refers to a non-refinement class type */
def checkClassType(tpt: Tree): Boolean = {
val tpe = unwrapToClass(tpt.tpe)
isNonRefinementClassType(tpe) || errorNotClass(tpt, tpe)
}
/** Check that `tpt` refers to a class type with a stable prefix. */
def checkStablePrefixClassType(tpt: Tree): Boolean = {
val tpe = unwrapToStableClass(tpt.tpe)
def prefixIsStable = {
def checkPre = tpe match {
case TypeRef(pre, _, _) => pre.isStable || errorNotStable(tpt, pre)
case _ => false
}
// A type projection like X#Y can get by the stable check if the
// prefix is singleton-bounded, so peek at the tree too.
def checkTree = tpt match {
case SelectFromTypeTree(qual, _) => isSingleType(qual.tpe) || errorNotClass(tpt, tpe)
case _ => true
}
checkPre && checkTree
}
( (isNonRefinementClassType(tpe) || errorNotClass(tpt, tpe))
&& (isPastTyper || prefixIsStable)
)
}
/** Check that type `tp` is not a subtype of itself.
*/
def checkNonCyclic(pos: Position, tp: Type): Boolean = {
def checkNotLocked(sym: Symbol) = {
sym.initialize.lockOK || { CyclicAliasingOrSubtypingError(pos, sym); false }
}
tp match {
case TypeRef(pre, sym, args) =>
checkNotLocked(sym) &&
((!sym.isNonClassType) || checkNonCyclic(pos, appliedType(pre.memberInfo(sym), args), sym))
// @M! info for a type ref to a type parameter now returns a polytype
// @M was: checkNonCyclic(pos, pre.memberInfo(sym).subst(sym.typeParams, args), sym)
case SingleType(_, sym) =>
checkNotLocked(sym)
case st: SubType =>
checkNonCyclic(pos, st.supertype)
case ct: CompoundType =>
ct.parents forall (x => checkNonCyclic(pos, x))
case _ =>
true
}
}
def checkNonCyclic(pos: Position, tp: Type, lockedSym: Symbol): Boolean = try {
if (!lockedSym.lock(CyclicReferenceError(pos, tp, lockedSym))) false
else checkNonCyclic(pos, tp)
} finally {
lockedSym.unlock()
}
def checkNonCyclic(sym: Symbol): Unit = {
if (!checkNonCyclic(sym.pos, sym.tpe_*)) sym.setInfo(ErrorType)
}
def checkNonCyclic(defn: Tree, tpt: Tree): Unit = {
if (!checkNonCyclic(defn.pos, tpt.tpe, defn.symbol)) {
tpt setType ErrorType
defn.symbol.setInfo(ErrorType)
}
}
def reenterValueParams(vparamss: List[List[ValDef]]): Unit = {
for (vparams <- vparamss)
for (vparam <- vparams)
context.scope enter vparam.symbol
}
def reenterTypeParams(tparams: List[TypeDef]): List[Symbol] =
for (tparam <- tparams) yield {
context.scope enter tparam.symbol
tparam.symbol.deSkolemize
}
/** The qualifying class
* of a this or super with prefix `qual`.
* packageOk is equal false when qualifying class symbol
*/
def qualifyingClass(tree: Tree, qual: Name, packageOK: Boolean, immediate: Boolean) =
context.enclClass.owner.ownersIterator.find(o => qual.isEmpty || o.isClass && o.name == qual) match {
case Some(c) if packageOK || !c.isPackageClass => c
case _ =>
QualifyingClassError(tree, qual)
// Delay `setError` in namer, scala/bug#10748
if (immediate) setError(tree) else unit.toCheck += (() => setError(tree))
NoSymbol
}
/** The typer for an expression, depending on where we are. If we are before a superclass
* call, this is a typer over a constructor context; otherwise it is the current typer.
*/
final def constrTyperIf(inConstr: Boolean): Typer =
if (inConstr) {
assert(context.undetparams.isEmpty, context.undetparams)
newTyper(context.makeConstructorContext)
} else this
@inline
final def withCondConstrTyper[T](inConstr: Boolean)(f: Typer => T): T =
if (inConstr) {
assert(context.undetparams.isEmpty, context.undetparams)
val c = context.makeConstructorContext
typerWithLocalContext(c)(f)
} else {
f(this)
}
@inline
final def typerWithCondLocalContext[T](c: => Context)(cond: Boolean)(f: Typer => T): T =
if (cond) typerWithLocalContext(c)(f) else f(this)
@inline
final def typerWithLocalContext[T](c: Context)(f: Typer => T): T = {
try f(newTyper(c))
finally c.reporter.propagateErrorsTo(context.reporter)
}
/** The typer for a label definition. If this is part of a template we
* first have to enter the label definition.
*/
def labelTyper(ldef: LabelDef): Typer =
if (ldef.symbol == NoSymbol) { // labeldef is part of template
val typer1 = newTyper(context.makeNewScope(ldef, context.owner))
typer1.enterLabelDef(ldef)
typer1
} else this
/** Is symbol defined and not stale?
*/
def reallyExists(sym: Symbol) = {
if (isStale(sym)) sym.setInfo(NoType)
sym.exists
}
/** A symbol is stale if it is toplevel, to be loaded from a classfile, and
* the classfile is produced from a sourcefile which is compiled in the current run.
*/
def isStale(sym: Symbol): Boolean = {
sym.rawInfo.isInstanceOf[loaders.ClassfileLoader] && {
sym.rawInfo.load(sym)
(sym.sourceFile ne null) &&
(currentRun.compiledFiles contains sym.sourceFile.path)
}
}
/** Does the context of tree `tree` require a stable type?
*/
private def isStableContext(tree: Tree, mode: Mode, pt: Type) = {
def ptSym = pt.typeSymbol
def expectsStable = (
pt.isStable
|| mode.inQualMode && !tree.symbol.isConstant
|| !(tree.tpe <:< pt) && (ptSym.isAbstractType && pt.lowerBound.isStable || ptSym.isRefinementClass)
)
( isNarrowable(tree.tpe)
&& mode.typingExprNotLhs
&& expectsStable
)
}
/** Make symbol accessible. This means:
* If symbol refers to package object, insert `.package` as second to last selector.
* (exception for some symbols in scala package which are dealiased immediately)
* Call checkAccessible, which sets tree's attributes.
* Also note that checkAccessible looks up sym on pre without checking that pre is well-formed
* (illegal type applications in pre will be skipped -- that's why typedSelect wraps the resulting tree in a TreeWithDeferredChecks)
* @return modified tree and new prefix type
*/
private def makeAccessible(tree: Tree, sym: Symbol, pre: Type, site: Tree): Any /*Type | (Tree, Type)*/ =
if (!unit.isJava && context.isInPackageObject(sym, pre.typeSymbol)) {
val qual = typedQualifier { atPos(tree.pos.makeTransparent) {
tree match {
case Ident(_) =>
val packageObject =
if (!sym.isOverloaded && sym.owner.isModuleClass) sym.owner.sourceModule // historical optimization, perhaps no longer needed
else pre.typeSymbol.packageObject
Ident(packageObject)
case Select(qual, _) => Select(qual, nme.PACKAGEkw)
case SelectFromTypeTree(qual, _) => Select(qual, nme.PACKAGEkw)
case x => throw new MatchError(x)
}
}}
val tree1 = atPos(tree.pos) {
tree match {
case Ident(name) => Select(qual, name)
case Select(_, name) => Select(qual, name)
case SelectFromTypeTree(_, name) => SelectFromTypeTree(qual, name)
case x => throw new MatchError(x)
}
}
(checkAccessible(tree1, sym, qual.tpe, qual, unit.isJava), qual.tpe)
} else {
checkAccessible(tree, sym, pre, site, unit.isJava)
}
/** Post-process an identifier or selection node, performing the following:
* 1. Check that non-function pattern expressions are stable (ignoring volatility concerns -- scala/bug#6815)
* (and narrow the type of modules: a module reference in a pattern has type Foo.type, not "object Foo")
* 2. Check that packages and static modules are not used as values
* 3. Turn tree type into stable type if possible and required by context.
* 4. Give getClass calls a more precise type based on the type of the target of the call.
*/
protected def stabilize(tree: Tree, pre: Type, mode: Mode, pt: Type): Tree = {
// Side effect time! Don't be an idiot like me and think you
// can move "val sym = tree.symbol" before this line, because
// inferExprAlternative side-effects the tree's symbol.
if (tree.symbol.isOverloaded && !mode.inFunMode)
inferExprAlternative(tree, pt)
val sym = tree.symbol
val isStableIdPattern = mode.typingPatternNotConstructor && tree.isTerm
def isModuleTypedExpr = (
treeInfo.admitsTypeSelection(tree)
&& (isStableContext(tree, mode, pt) || sym.isModuleNotMethod)
)
def isStableValueRequired = (
isStableIdPattern
|| mode.in(all = EXPRmode, none = QUALmode) && !phase.erasedTypes
)
// To fully benefit from special casing the return type of
// getClass, we have to catch it immediately so expressions like
// x.getClass().newInstance() are typed with the type of x. TODO: If the
// type of the qualifier is inaccessible, we can cause private types to
// escape scope here, e.g. pos/t1107. I'm not sure how to properly handle
// this so for now it requires the type symbol be public.
def isGetClassCall = isGetClass(sym) && pre.typeSymbol.isPublic
def narrowIf(tree: Tree, condition: Boolean) =
if (condition) tree setType singleType(pre, sym) else tree
def checkStable(tree: Tree): Tree =
if (treeInfo.isStableIdentifierPattern(tree)) tree
else UnstableTreeError(tree)
if (tree.isErrorTyped)
tree
else if (!sym.isValue && isStableValueRequired) // (2)
NotAValueError(tree, sym)
else if (isStableIdPattern) // (1)
// A module reference in a pattern has type Foo.type, not "object Foo"
narrowIf(checkStable(tree), sym.isModuleNotMethod)
else if (isModuleTypedExpr) // (3)
narrowIf(tree, true)
else if (isGetClassCall) // (4)
tree setType MethodType(Nil, getClassReturnType(pre))
else
tree
}
private def isNarrowable(tpe: Type): Boolean = unwrapWrapperTypes(tpe) match {
case TypeRef(_, _, _) | RefinedType(_, _) => true
case _ => !phase.erasedTypes
}
def stabilizeFun(tree: Tree, mode: Mode, pt: Type): Tree = {
val sym = tree.symbol
val pre = tree match {
case Select(qual, _) => qual.tpe
case _ => NoPrefix
}
def stabilizable = (
pre.isStable
&& sym.tpe.params.isEmpty
&& (isStableContext(tree, mode, pt) || sym.isModule)
)
tree.tpe match {
case MethodType(_, _) if stabilizable => tree setType MethodType(Nil, singleType(pre, sym)) // TODO: should this be a NullaryMethodType?
case _ => tree
}
}
@deprecated("Use the overload accepting a Type.", "2.12.9")
def member(qual: Tree, name: Name): Symbol = member(qual.tpe, name)
/** The member with given name of given qualifier type */
def member(qual: Type, name: Name): Symbol = {
def callSiteWithinClass(clazz: Symbol) = context.enclClass.owner hasTransOwner clazz
val includeLocals = qual match {
case ThisType(clazz) if callSiteWithinClass(clazz) => true
case SuperType(clazz, _) if callSiteWithinClass(clazz.typeSymbol) => true
case _ => phase.next.erasedTypes
}
if (includeLocals) qual member name
else qual nonLocalMember name
}
def silent[T](op: Typer => T,
reportAmbiguousErrors: Boolean = context.ambiguousErrors,
newtree: Tree = context.tree): SilentResult[T] = {
val findMemberStart = if (StatisticsStatics.areSomeColdStatsEnabled) statistics.startCounter(findMemberFailed) else null
val subtypeStart = if (StatisticsStatics.areSomeColdStatsEnabled) statistics.startCounter(subtypeFailed) else null
val failedSilentStart = if (StatisticsStatics.areSomeColdStatsEnabled) statistics.startTimer(failedSilentNanos) else null
def stopStats() = {
if (StatisticsStatics.areSomeColdStatsEnabled) statistics.stopCounter(findMemberFailed, findMemberStart)
if (StatisticsStatics.areSomeColdStatsEnabled) statistics.stopCounter(subtypeFailed, subtypeStart)
if (StatisticsStatics.areSomeColdStatsEnabled) statistics.stopTimer(failedSilentNanos, failedSilentStart)
}
@inline def wrapResult(reporter: ContextReporter, result: T) =
if (reporter.hasErrors) {
stopStats()
SilentTypeError(reporter.errors.toList, reporter.warnings.toList)
} else SilentResultValue(result)
try {
if (context.reportErrors ||
reportAmbiguousErrors != context.ambiguousErrors ||
newtree != context.tree) {
val context1 = context.makeSilent(reportAmbiguousErrors, newtree)
context1.undetparams = context.undetparams
context1.savedTypeBounds = context.savedTypeBounds
context1.pendingStabilizers = context.pendingStabilizers
val typer1 = newTyper(context1)
val result = op(typer1)
context.undetparams = context1.undetparams
context.savedTypeBounds = context1.savedTypeBounds
context.pendingStabilizers = context1.pendingStabilizers
// If we have a successful result, emit any warnings it created.
if (!context1.reporter.hasErrors)
context1.reporter.emitWarnings()
wrapResult(context1.reporter, result)
} else {
assert(context.bufferErrors || isPastTyper, "silent mode is not available past typer")
context.reporter.withFreshErrorBuffer {
wrapResult(context.reporter, op(this))
}
}
} catch {
case ex: CyclicReference => throw ex
case ex: TypeError =>
// fallback in case TypeError is still thrown
// @H this happens for example in cps annotation checker
stopStats()
SilentTypeError(TypeErrorWrapper(ex))
}
}
/** Check whether feature given by `featureTrait` is enabled.
* If it is not, issue an error or a warning depending on whether the feature is required.
* @param construct A string expression that is substituted for "#" in the feature description string
* @param immediate When set, feature check is run immediately, otherwise it is run
* at the end of the typechecking run for the enclosing unit. This
* is done to avoid potential cyclic reference errors by implicits
* that are forced too early.
* @return if feature check is run immediately: true if feature is enabled, false otherwise
* if feature check is delayed or suppressed because we are past typer: true
*/
def checkFeature(pos: Position, featureTrait: Symbol, construct: => String = "", immediate: Boolean = false): Boolean =
isPastTyper || {
val nestedOwners =
featureTrait.owner.ownerChain.takeWhile(_ != languageFeatureModule.moduleClass).reverse
val featureName = nestedOwners.map(s => s"${s.name}.").mkString + featureTrait.name
def action(): Boolean = {
def hasImport = inferImplicitByType(featureTrait.tpe, context).isSuccess
def hasOption = settings.language.contains(featureName)
hasOption || hasImport || {
val Some(AnnotationInfo(_, List(Literal(Constant(featureDesc: String)), Literal(Constant(required: Boolean))), _)) =
featureTrait.getAnnotation(LanguageFeatureAnnot): @unchecked
context.featureWarning(pos, featureName, featureDesc, featureTrait, construct, required)
false
}
}
if (immediate) {
action()
} else {
unit.toCheck += (() => action())
true
}
}
def checkExistentialsFeature(pos: Position, tpe: Type, prefix: String) = tpe match {
case extp: ExistentialType if !extp.isRepresentableWithWildcards && !tpe.isError =>
checkFeature(pos, currentRun.runDefinitions.ExistentialsFeature, prefix+" "+tpe)
case _ =>
}
/** Perform the following adaptations of expression, pattern or type `tree` wrt to
* given mode `mode` and given prototype `pt`:
* (-1) For expressions with annotated types, let AnnotationCheckers decide what to do
* (0) Convert expressions with constant types to literals (unless in interactive/scaladoc mode)
* (1) Resolve overloading, unless mode contains FUNmode
* (2) Apply parameterless functions
* (3) Apply polymorphic types to fresh instances of their type parameters and
* store these instances in context.undetparams,
* unless followed by explicit type application.
* (4) Do the following to unapplied methods used as values:
* (4.1) If the method has only implicit parameters, pass implicit arguments (see adaptToImplicitMethod)
* (4.2) otherwise, if the method is 0-ary and it can be auto-applied (see checkCanAutoApply), apply it to ()
* (4.3) otherwise, if the method is not a constructor, and can be eta-expanded (see checkCanEtaExpand), eta-expand
* otherwise issue an error
* (5) Convert constructors in a pattern as follows:
* (5.1) If constructor refers to a case class factory, set tree's type to the unique
* instance of its primary constructor that is a subtype of the expected type.
* (5.2) If constructor refers to an extractor, convert to application of
* unapply or unapplySeq method.
*
* (6) Convert all other types to TypeTree nodes.
* (7) When in TYPEmode but not FUNmode or HKmode, check that types are fully parameterized
* (7.1) In HKmode, higher-kinded types are allowed, but they must have the expected kind-arity
* (8) When in both EXPRmode and FUNmode, add apply method calls to values of object type.
* (9) If there are undetermined type variables and not POLYmode, infer expression instance
* Then, if tree's type is not a subtype of expected type, try the following adaptations:
* (10) If the expected type is Byte, Short or Char, and the expression
* is an integer fitting in the range of that type, convert it to that type.
* (11) Widen numeric literals to their expected type, if necessary
* (12) When in mode EXPRmode, convert E to { E; () } if expected type is scala.Unit.
* (13) When in mode EXPRmode, apply AnnotationChecker conversion if expected type is annotated.
* (14) When in mode EXPRmode, do SAM conversion
* (15) When in mode EXPRmode, apply a view
* If all this fails, error
*
* Note: the `original` tree parameter is for re-typing implicit method invocations (see below)
* and should not be used otherwise. TODO: can it be replaced with a tree attachment?
*/
protected def adapt(tree: Tree, mode: Mode, pt: Type, original: Tree = EmptyTree): Tree = {
def hasUndets = !context.undetparams.isEmpty
def hasUndetsInMonoMode = hasUndets && !mode.inPolyMode
def adaptToImplicitMethod(mt: MethodType): Tree = {
if (hasUndets) { // (9) -- should revisit dropped condition `hasUndetsInMonoMode`
// dropped so that type args of implicit method are inferred even if polymorphic expressions are allowed
// needed for implicits in 2.8 collection library -- maybe once #3346 is fixed, we can reinstate the condition?
context.undetparams = inferExprInstance(tree, context.extractUndetparams(), pt,
// approximate types that depend on arguments since dependency on implicit argument is like dependency on type parameter
mt.approximate,
keepNothings = false,
useWeaklyCompatible = true) // #3808
}
// avoid throwing spurious DivergentImplicit errors
if (context.reporter.hasErrors)
setError(tree)
else
withCondConstrTyper(treeInfo.isSelfOrSuperConstrCall(tree))(typer1 =>
if (original != EmptyTree && !pt.isWildcard) {
typer1 silent { tpr =>
val withImplicitArgs = tpr.applyImplicitArgs(tree)
if (tpr.context.reporter.hasErrors) tree // silent will wrap it in SilentTypeError anyway
else tpr.typed(withImplicitArgs, mode, pt)
} orElse { originalErrors =>
// Re-try typing (applying to implicit args) without expected type. Add in 53d98e7d42 to
// for better error message (scala/bug#2180, http://www.scala-lang.org/old/node/3453.html)
val resetTree = resetAttrs(original)
resetTree match {
case treeInfo.Applied(fun, _, _) =>
if (fun.symbol != null && fun.symbol.isError)
// scala/bug#9041 Without this, we leak error symbols past the typer!
// because the fallback typechecking notices the error-symbol,
// refuses to re-attempt typechecking, and presumes that someone
// else was responsible for issuing the related type error!
fun.setSymbol(NoSymbol)
case _ =>
}
debuglog(s"fallback on implicits: $tree/$resetTree")
// scala/bug#10066 Need to patch the enclosing tree in the context to make translation of Dynamic
// work during fallback typechecking below.
val resetContext: Context = {
object substResetForOriginal extends AstTransformer {
override def transform(tree: Tree): Tree = {
if (tree eq original) resetTree
else super.transform(tree)
}
}
context.make(substResetForOriginal.transform(context.tree))
}
typerWithLocalContext(resetContext) { typer1 =>
typer1.silent { typer1 =>
val tree1 = typer1.typed(resetTree, mode)
// Q: `typed` already calls `pluginsTyped` and `adapt`. the only difference here is that
// we pass `EmptyTree` as the `original`. intended? added in 2009 (53d98e7d42) by martin.
tree1 setType pluginsTyped(tree1.tpe, typer1, tree1, mode, pt)
if (tree1.isEmpty) tree1 else typer1.adapt(tree1, mode, pt, original = EmptyTree)
} orElse { _ =>
originalErrors.foreach(context.issue)
setError(tree)
}
}
}
}
else
typer1.typed(typer1.applyImplicitArgs(tree), mode, pt)
)
}
def adaptMethodTypeToExpr(mt: MethodType): Tree = {
val meth =
tree match {
// a partial named application is a block (see comment in EtaExpansion)
// How about user-written blocks? Can they ever have a MethodType?
case Block(_, tree1) => tree1.symbol
case _ => tree.symbol
}
val arity = mt.params.length
val sourceLevel3 = currentRun.isScala3
def warnTree = original orElse tree
def warnEtaZero(): Boolean = {
if (!settings.warnEtaZero) return true
context.warning(tree.pos,
s"""An unapplied 0-arity method was eta-expanded (due to the expected type $pt), rather than applied to `()`.
|Write ${Apply(warnTree, Nil)} to invoke method ${meth.decodedName}, or change the expected type.""".stripMargin,
WarningCategory.LintEtaZero)
true
}
def warnEtaSam(): Boolean = {
if (!settings.warnEtaSam) return true
val sam = samOf(pt)
val samClazz = sam.owner
// TODO: we allow a Java class as a SAM type, whereas Java only allows the @FunctionalInterface on interfaces -- align?
if (sam.exists && (!samClazz.hasFlag(JAVA) || samClazz.hasFlag(INTERFACE)) && !samClazz.hasAnnotation(definitions.FunctionalInterfaceClass))
context.warning(tree.pos,
s"""Eta-expansion performed to meet expected type $pt, which is SAM-equivalent to ${samToFunctionType(pt)},
|even though $samClazz is not annotated with `@FunctionalInterface`;
|to suppress warning, add the annotation or write out the equivalent function literal.""".stripMargin,
WarningCategory.LintEtaSam)
true
}
// note that isFunctionProto(pt) does not work properly for Function0
lazy val ptUnderlying =
(pt match {
case oapt: OverloadedArgProto => oapt.underlying
case pt => pt
}).dealiasWiden
// (4.3) condition for eta-expansion by arity & -Xsource level
//
// for arity == 0:
// - if Function0 is expected -- SAM types do not eta-expand because it could be an accidental SAM scala/bug#9489
// for arity > 0:
// - 2.13: if function or sam type is expected
// - 3.0: unconditionally
//
// warnings:
// - for arity == 0: eta-expansion of zero-arg methods was deprecated (scala/bug#7187)
// - for arity > 0: expected type is a SAM that is not annotated with `@FunctionalInterface`
def checkCanEtaExpand(): Boolean = {
def expectingSamOfArity = {
val sam = samOf(ptUnderlying)
sam.exists && sam.info.params.lengthIs == arity
}
val expectingFunctionOfArity = {
val ptSym = ptUnderlying.typeSymbolDirect
(ptSym eq FunctionClass(arity)) || (arity > 0 && (ptSym eq FunctionClass(1))) // allowing for tupling conversion
}
if (arity == 0)
expectingFunctionOfArity && warnEtaZero()
else
expectingFunctionOfArity || expectingSamOfArity && warnEtaSam() || sourceLevel3
}
def matchNullaryLoosely: Boolean = {
def test(sym: Symbol) = sym.isJavaDefined || sym.owner == AnyClass
test(meth) || meth.overrides.exists(test)
}
// (4.2) condition for auto-application
//
// Currently the condition is more involved to give slack to Scala methods overriding Java-defined ones;
// I (moors) think we should resolve that by introducing slack in overriding e.g. a Java-defined `def toString()` by a Scala-defined `def toString`.
// This also works better for dealing with accessors overriding Java-defined methods. The current strategy in methodSig is problematic:
// > // Add a () parameter section if this overrides some method with () parameters
// > val vparamSymssOrEmptyParamsFromOverride =
// This means an accessor that overrides a Java-defined method gets a MethodType instead of a NullaryMethodType, which breaks lots of assumptions about accessors)
def checkCanAutoApply(): Boolean = {
if (!isPastTyper && !matchNullaryLoosely) {
context.deprecationWarning(tree.pos, NoSymbol, s"Auto-application to `()` is deprecated. Supply the empty argument list `()` explicitly to invoke method ${meth.decodedName},\n" +
s"or remove the empty argument list from its definition (Java-defined methods are exempt).\n"+
s"In Scala 3, an unapplied method like this will be eta-expanded into a function.", "2.13.3")
}
true
}
if (!meth.isConstructor && checkCanEtaExpand()) typedEtaExpansion(tree, mode, pt)
else if (arity == 0 && checkCanAutoApply()) adapt(typed(Apply(tree, Nil) setPos tree.pos), mode, pt, original)
else
if (context.implicitsEnabled) MissingArgsForMethodTpeError(tree, meth) // `context.implicitsEnabled` implies we are not in a pattern
else UnstableTreeError(tree)
}
def adaptType(): Tree = {
// @M When not typing a type constructor (!context.inTypeConstructorAllowed)
// or raw type, types must be of kind *,
// and thus parameterized types must be applied to their type arguments
// @M TODO: why do kind-* tree's have symbols, while higher-kinded ones don't?
def properTypeRequired = (
tree.hasSymbolField
&& !context.inTypeConstructorAllowed
&& !context.unit.isJava
)
// @M: don't check tree.tpe.symbol.typeParams. check tree.tpe.typeParams!!!
// (e.g., m[Int] --> tree.tpe.symbol.typeParams.length == 1, tree.tpe.typeParams.length == 0!)
// @M: removed check for tree.hasSymbolField and replace tree.symbol by tree.tpe.symbol
// (TypeTree's must also be checked here, and they don't directly have a symbol)
def kindArityMismatch = (
context.inTypeConstructorAllowed
&& !sameLength(tree.tpe.typeParams, pt.typeParams)
)
// Note that we treat Any and Nothing as kind-polymorphic.
// We can't perform this check when typing type arguments to an overloaded method before the overload is resolved
// (or in the case of an error type) -- this is indicated by pt == WildcardType (see case TypeApply in typed1).
def kindArityMismatchOk = tree.tpe.typeSymbol match {
case NothingClass | AnyClass => true
case _ => pt == WildcardType
}
// todo. It would make sense when mode.inFunMode to instead use
// tree setType tree.tpe.normalize
// when typechecking, say, TypeApply(Ident(`some abstract type symbol`), List(...))