/
Typers.scala
5853 lines (5331 loc) · 276 KB
/
Typers.scala
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/* NSC -- new Scala compiler
* Copyright 2005-2013 LAMP/EPFL
* @author Martin Odersky
*/
// Added: Sat Oct 7 16:08:21 2006
//todo: use inherited type info also for vars and values
// Added: Thu Apr 12 18:23:58 2007
//todo: disallow C#D in superclass
//todo: treat :::= correctly
package scala.tools.nsc
package typechecker
import scala.collection.mutable
import scala.reflect.internal.util.{ BatchSourceFile, Statistics }
import mutable.ListBuffer
import symtab.Flags._
// Suggestion check whether we can do without priming scopes with symbols of outer scopes,
// like the IDE does.
/** This trait provides methods to assign types to trees.
*
* @author Martin Odersky
* @version 1.0
*/
trait Typers extends Modes with Adaptations with Tags {
self: Analyzer =>
import global._
import definitions._
import TypersStats._
final def forArgMode(fun: Tree, mode: Int) =
if (treeInfo.isSelfOrSuperConstrCall(fun)) mode | SCCmode
else mode
// namer calls typer.computeType(rhs) on DefDef / ValDef when tpt is empty. the result
// is cached here and re-used in typedDefDef / typedValDef
// Also used to cache imports type-checked by namer.
val transformed = new mutable.HashMap[Tree, Tree]
final val shortenImports = false
def resetTyper() {
//println("resetTyper called")
resetContexts()
resetImplicits()
transformed.clear()
clearDocComments()
}
object UnTyper extends Traverser {
override def traverse(tree: Tree) = {
if (tree != EmptyTree) tree.tpe = null
if (tree.hasSymbol) tree.symbol = NoSymbol
super.traverse(tree)
}
}
/* needed for experimental version where early types can be type arguments
class EarlyMap(clazz: Symbol) extends TypeMap {
def apply(tp: Type): Type = tp match {
case TypeRef(NoPrefix, sym, List()) if (sym hasFlag PRESUPER) =>
TypeRef(ThisType(clazz), sym, List())
case _ =>
mapOver(tp)
}
}
*/
sealed abstract class SilentResult[+T]
case class SilentTypeError(err: AbsTypeError) extends SilentResult[Nothing] { }
case class SilentResultValue[+T](value: T) extends SilentResult[T] { }
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 def isPastTyper = phase.id > currentRun.typerPhase.id
// To enable decent error messages when the typer crashes.
// TODO - this only catches trees which go through def typed,
// but there are all kinds of back ways - typedClassDef, etc. etc.
// Funnel everything through one doorway.
var lastTreeToTyper: Tree = EmptyTree
// when true:
// - we may virtualize matches (if -Xexperimental and there's a suitable __match in scope)
// - we synthesize PartialFunction implementations for `x => x match {...}` and `match {...}` when the expected type is PartialFunction
// this is disabled by: -Xoldpatmat or interactive compilation (we run it for scaladoc due to SI-5933)
private def newPatternMatching = opt.virtPatmat && !forInteractive //&& !forScaladoc && (phase.id < currentRun.uncurryPhase.id)
abstract class Typer(context0: Context) extends TyperDiagnostics with Adaptation with Tag with TyperContextErrors {
import context0.unit
import typeDebug.{ ptTree, ptBlock, ptLine }
import TyperErrorGen._
val infer = new Inferencer(context0) {
override def isCoercible(tp: Type, pt: Type): Boolean = undoLog undo { // #3281
tp.isError || pt.isError ||
context0.implicitsEnabled && // this condition prevents chains of views
inferView(EmptyTree, tp, pt, false) != EmptyTree
}
}
/** 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
def mkPositionalArg(argTree: Tree, paramName: Name) = argTree
def mkNamedArg(argTree: Tree, paramName: Name) = atPos(argTree.pos)(new AssignOrNamedArg(Ident(paramName), (argTree)))
var mkArg: (Tree, Name) => Tree = mkPositionalArg
// 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.isError && {paramFailed = true; true})) SearchFailure else inferImplicit(fun, paramTp, context.reportErrors, false, context)
argResultsBuff += res
if (res.isSuccess) {
argBuff += mkArg(res.tree, param.name)
} else {
mkArg = mkNamedArg // don't pass the default argument (if any) here, but start emitting named arguments for the following args
if (!param.hasDefault && !paramFailed) {
context.errBuffer.find(_.kind == ErrorKinds.Divergent) match {
case Some(divergentImplicit) if !settings.Xdivergence211.value =>
// DivergentImplicit error has higher priority than "no implicit found"
// no need to issue the problem again if we are still in silent mode
if (context.reportErrors) {
context.issue(divergentImplicit)
context.condBufferFlush(_.kind == ErrorKinds.Divergent)
}
case Some(divergentImplicit: DivergentImplicitTypeError) if settings.Xdivergence211.value =>
if (context.reportErrors) {
context.issue(divergentImplicit.withPt(paramTp))
context.condBufferFlush(_.kind == ErrorKinds.Divergent)
}
case None =>
NoImplicitFoundError(fun, param)
}
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
}
def inferView(tree: Tree, from: Type, to: Type, reportAmbiguous: Boolean): Tree =
inferView(tree, from, to, reportAmbiguous, true)
/** 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, saveErrors: Boolean): Tree = {
debuglog("infer view from "+from+" to "+to)//debug
if (isPastTyper) EmptyTree
else from match {
case MethodType(_, _) => EmptyTree
case OverloadedType(_, _) => EmptyTree
case PolyType(_, _) => EmptyTree
case _ =>
def wrapImplicit(from: Type): Tree = {
val result = inferImplicit(tree, functionType(from :: Nil, to), reportAmbiguous, true, context, saveErrors)
if (result.subst != EmptyTreeTypeSubstituter) {
result.subst traverse tree
notifyUndetparamsInferred(result.subst.from, result.subst.to)
}
result.tree
}
wrapImplicit(from) orElse wrapImplicit(byNameType(from))
}
}
import infer._
private var namerCache: Namer = null
def 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, tpe) =>
new SubstWildcardMap(tparams).apply(tp)
case TypeRef(_, sym, _) if sym.isAliasType =>
val tp0 = tp.dealias
if (tp eq tp0) {
debugwarn(s"dropExistential did not progress dealiasing $tp, see SI-7126")
tp
} else {
val tp1 = dropExistential(tp0)
if (tp1 eq tp0) tp else tp1
}
case _ => tp
}
/** Check that <code>tree</code> is a stable expression.
*
* @param tree ...
* @return ...
*/
def checkStable(tree: Tree): Tree = (
if (treeInfo.isExprSafeToInline(tree)) tree
else if (tree.isErrorTyped) tree
else UnstableTreeError(tree)
)
/** Would tree be a stable (i.e. a pure expression) if the type
* of its symbol was not volatile?
*/
protected def isStableExceptVolatile(tree: Tree) = {
tree.hasSymbol && tree.symbol != NoSymbol && tree.tpe.isVolatile &&
{ val savedTpe = tree.symbol.info
val savedSTABLE = tree.symbol getFlag STABLE
tree.symbol setInfo AnyRefClass.tpe
tree.symbol setFlag STABLE
val result = treeInfo.isExprSafeToInline(tree)
tree.symbol setInfo savedTpe
tree.symbol setFlag savedSTABLE
result
}
}
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 <code>tp</code> is not a subtype of itself.
*
* @param pos ...
* @param tp ...
* @return <code>true</code> if <code>tp</code> is not a subtype of itself.
*/
def checkNonCyclic(pos: Position, tp: Type): Boolean = {
def checkNotLocked(sym: Symbol) = {
sym.initialize
sym.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(pre, sym) =>
checkNotLocked(sym)
/*
case TypeBounds(lo, hi) =>
var ok = true
for (t <- lo) ok = ok & checkNonCyclic(pos, t)
ok
*/
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, lockedSym))) false
else checkNonCyclic(pos, tp)
} finally {
lockedSym.unlock()
}
def checkNonCyclic(sym: Symbol) {
if (!checkNonCyclic(sym.pos, sym.tpe)) sym.setInfo(ErrorType)
}
def checkNonCyclic(defn: Tree, tpt: Tree) {
if (!checkNonCyclic(defn.pos, tpt.tpe, defn.symbol)) {
tpt.tpe = ErrorType
defn.symbol.setInfo(ErrorType)
}
}
def checkParamsConvertible(tree: Tree, tpe0: Type) {
def checkParamsConvertible0(tpe: Type) =
tpe match {
case MethodType(formals, restpe) =>
/*
if (formals.exists(_.typeSymbol == ByNameParamClass) && formals.length != 1)
error(pos, "methods with `=>`-parameter can be converted to function values only if they take no other parameters")
if (formals exists (isRepeatedParamType(_)))
error(pos, "methods with `*`-parameters cannot be converted to function values");
*/
if (tpe.isDependentMethodType)
DependentMethodTpeConversionToFunctionError(tree, tpe)
checkParamsConvertible(tree, restpe)
case _ =>
}
checkParamsConvertible0(tpe0)
}
/** 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 <code>tree</code> does not refer to private
* components unless itself is wrapped in something private
* (<code>owner</code> tells where the type occurs).
*
* @param owner ...
* @param tree ...
* @return ...
*/
def privates[T <: Tree](owner: Symbol, tree: T): T =
check(owner, EmptyScope, WildcardType, tree)
/** Check that type <code>tree</code> does not refer to entities
* defined in scope <code>scope</code>.
*
* @param scope ...
* @param pt ...
* @param tree ...
* @return ...
*/
def locals[T <: Tree](scope: Scope, pt: Type, tree: T): T =
check(NoSymbol, scope, pt, tree)
private def check[T <: Tree](owner: Symbol, scope: Scope, pt: Type, tree: T): T = {
this.owner = owner
this.scope = scope
hiddenSymbols = List()
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(owner, scope, pt, tree setType tp1.typeSymbol.classBound)
else if (owner == NoSymbol)
tree setType packSymbols(hiddenSymbols.reverse, tp1)
else if (!phase.erasedTypes) { // 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) {
if (sym.isPrivate && !sym.hasFlag(SYNTHETIC_PRIVATE)) {
var o = owner
while (o != NoSymbol && o != sym.owner && o != sym.owner.linkedClassOfClass &&
!o.isLocal && !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
})
}
}
def reenterValueParams(vparamss: List[List[ValDef]]) {
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 <code>qual</code>.
* packageOk is equal false when qualifying class symbol
*/
def qualifyingClass(tree: Tree, qual: Name, packageOK: Boolean) =
context.enclClass.owner.ownerChain.find(o => qual.isEmpty || o.isClass && o.name == qual) match {
case Some(c) if packageOK || !c.isPackageClass => c
case _ => QualifyingClassError(tree, qual) ; 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 = {
val res = f(newTyper(c))
if (c.hasErrors)
context.updateBuffer(c.flushAndReturnBuffer())
res
}
@inline
final def typerReportAnyContextErrors[T](c: Context)(f: Typer => T): T = {
f(newTyper(c))
}
@inline
final def withSavedContext[T](c: Context)(f: => T) = {
val savedErrors = c.flushAndReturnBuffer()
val res = f
c.updateBuffer(savedErrors)
res
}
/** 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
final val xtypes = false
/** 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 <code>tree</code> require a stable type?
*/
private def isStableContext(tree: Tree, mode: Int, pt: Type) =
isNarrowable(tree.tpe) && ((mode & (EXPRmode | LHSmode)) == EXPRmode) &&
(xtypes ||
(pt.isStable ||
(mode & QUALmode) != 0 && !tree.symbol.isConstant ||
pt.typeSymbol.isAbstractType && pt.bounds.lo.isStable && !(tree.tpe <:< pt)) ||
pt.typeSymbol.isRefinementClass && !(tree.tpe <:< pt))
/** 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): (Tree, Type) =
if (isInPackageObject(sym, pre.typeSymbol)) {
if (pre.typeSymbol == ScalaPackageClass && sym.isTerm) {
// short cut some aliases. It seems pattern matching needs this
// to notice exhaustiveness and to generate good code when
// List extractors are mixed with :: patterns. See Test5 in lists.scala.
def dealias(sym: Symbol) =
(atPos(tree.pos.makeTransparent) {gen.mkAttributedRef(sym)} setPos tree.pos, sym.owner.thisType)
sym.name match {
case nme.List => return dealias(ListModule)
case nme.Seq => return dealias(SeqModule)
case nme.Nil => return dealias(NilModule)
case _ =>
}
}
val qual = typedQualifier { atPos(tree.pos.makeTransparent) {
tree match {
case Ident(_) => Ident(nme.PACKAGEkw)
case Select(qual, _) => Select(qual, nme.PACKAGEkw)
case SelectFromTypeTree(qual, _) => Select(qual, nme.PACKAGEkw)
}
}}
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)
}
}
(checkAccessible(tree1, sym, qual.tpe, qual), qual.tpe)
} else {
(checkAccessible(tree, sym, pre, site), pre)
}
/** Is `sym` defined in package object of package `pkg`?
*/
private def isInPackageObject(sym: Symbol, pkg: Symbol) = {
def isInPkgObj(sym: Symbol) =
!sym.owner.isPackage && {
sym.owner.isPackageObjectClass &&
sym.owner.owner == pkg ||
pkg.isInitialized && {
// need to be careful here to not get a cyclic reference during bootstrap
val pkgobj = pkg.info.member(nme.PACKAGEkw)
pkgobj.isInitialized &&
(pkgobj.info.member(sym.name).alternatives contains sym)
}
}
pkg.isPackageClass && {
if (sym.isOverloaded) sym.alternatives forall isInPkgObj
else isInPkgObj(sym)
}
}
/** Post-process an identifier or selection node, performing the following:
* 1. Check that non-function pattern expressions are stable
* 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.
*/
private def stabilize(tree: Tree, pre: Type, mode: Int, pt: Type): Tree = {
if (tree.symbol.isOverloaded && !inFunMode(mode))
inferExprAlternative(tree, pt)
val sym = tree.symbol
def fail() = NotAValueError(tree, sym)
if (tree.isErrorTyped) tree
else if ((mode & (PATTERNmode | FUNmode)) == PATTERNmode && tree.isTerm) { // (1)
if (sym.isValue) {
val tree1 = checkStable(tree)
// A module reference in a pattern has type Foo.type, not "object Foo"
if (sym.isModule && !sym.isMethod) tree1 setType singleType(pre, sym)
else tree1
}
else fail()
} else if ((mode & (EXPRmode | QUALmode)) == EXPRmode && !sym.isValue && !phase.erasedTypes) { // (2)
fail()
} else {
if (sym.isStable && pre.isStable && !isByNameParamType(tree.tpe) &&
(isStableContext(tree, mode, pt) || sym.isModule && !sym.isMethod))
tree.setType(singleType(pre, sym))
// 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.
else if ( isGetClass(tree.symbol)
// 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.
&& pre.typeSymbol.isPublic)
tree setType MethodType(Nil, getClassReturnType(pre))
else
tree
}
}
private def isNarrowable(tpe: Type): Boolean = unwrapWrapperTypes(tpe) match {
case TypeRef(_, _, _) | RefinedType(_, _) => true
case _ => !phase.erasedTypes
}
/**
* @param tree ...
* @param mode ...
* @param pt ...
* @return ...
*/
def stabilizeFun(tree: Tree, mode: Int, pt: Type): Tree = {
val sym = tree.symbol
val pre = tree match {
case Select(qual, _) => qual.tpe
case _ => NoPrefix
}
if (tree.tpe.isInstanceOf[MethodType] && pre.isStable && sym.tpe.params.isEmpty &&
(isStableContext(tree, mode, pt) || sym.isModule))
tree.setType(MethodType(List(), singleType(pre, sym))) // TODO: should this be a NullaryMethodType?
else tree
}
/** The member with given name of given qualifier tree */
def member(qual: Tree, name: Name) = {
def callSiteWithinClass(clazz: Symbol) = context.enclClass.owner hasTransOwner clazz
val includeLocals = qual.tpe match {
case ThisType(clazz) if callSiteWithinClass(clazz) => true
case SuperType(clazz, _) if callSiteWithinClass(clazz.typeSymbol) => true
case _ => phase.next.erasedTypes
}
if (includeLocals) qual.tpe member name
else qual.tpe nonLocalMember name
}
def silent[T](op: Typer => T,
reportAmbiguousErrors: Boolean = context.ambiguousErrors,
newtree: Tree = context.tree): SilentResult[T] = {
val rawTypeStart = if (Statistics.canEnable) Statistics.startCounter(rawTypeFailed) else null
val findMemberStart = if (Statistics.canEnable) Statistics.startCounter(findMemberFailed) else null
val subtypeStart = if (Statistics.canEnable) Statistics.startCounter(subtypeFailed) else null
val failedSilentStart = if (Statistics.canEnable) Statistics.startTimer(failedSilentNanos) else null
def stopStats() = {
if (Statistics.canEnable) Statistics.stopCounter(rawTypeFailed, rawTypeStart)
if (Statistics.canEnable) Statistics.stopCounter(findMemberFailed, findMemberStart)
if (Statistics.canEnable) Statistics.stopCounter(subtypeFailed, subtypeStart)
if (Statistics.canEnable) Statistics.stopTimer(failedSilentNanos, failedSilentStart)
}
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.namedApplyBlockInfo = context.namedApplyBlockInfo
val typer1 = newTyper(context1)
val result = op(typer1)
context.undetparams = context1.undetparams
context.savedTypeBounds = context1.savedTypeBounds
context.namedApplyBlockInfo = context1.namedApplyBlockInfo
if (context1.hasErrors) {
stopStats()
SilentTypeError(context1.errBuffer.head)
} else {
// If we have a successful result, emit any warnings it created.
if (context1.hasWarnings) {
context1.flushAndReturnWarningsBuffer() foreach {
case (pos, msg) => unit.warning(pos, msg)
}
}
SilentResultValue(result)
}
} else {
assert(context.bufferErrors || isPastTyper, "silent mode is not available past typer")
withSavedContext(context){
val res = op(this)
val errorsToReport = context.flushAndReturnBuffer()
if (errorsToReport.isEmpty) SilentResultValue(res) else SilentTypeError(errorsToReport.head)
}
}
} 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 =
if (isPastTyper) true
else {
val nestedOwners =
featureTrait.owner.ownerChain.takeWhile(_ != languageFeatureModule.moduleClass).reverse
val featureName = (nestedOwners map (_.name + ".")).mkString + featureTrait.name
def action(): Boolean = {
def hasImport = inferImplicit(EmptyTree: Tree, featureTrait.tpe, true, false, context).isSuccess
def hasOption = settings.language.value exists (s => s == featureName || s == "_")
val OK = hasImport || hasOption
if (!OK) {
val Some(AnnotationInfo(_, List(Literal(Constant(featureDesc: String)), Literal(Constant(required: Boolean))), _)) =
featureTrait getAnnotation LanguageFeatureAnnot
val req = if (required) "needs to" else "should"
val fqname = "scala.language." + featureName
val explain = (
if (currentRun.reportedFeature contains featureTrait) "" else
s"""|
|This can be achieved by adding the import clause 'import $fqname'
|or by setting the compiler option -language:$featureName.
|See the Scala docs for value $fqname for a discussion
|why the feature $req be explicitly enabled.""".stripMargin
)
currentRun.reportedFeature += featureTrait
val msg = s"$featureDesc $req be enabled\nby making the implicit value $fqname visible.$explain" replace ("#", construct)
if (required) unit.error(pos, msg)
else currentRun.featureWarnings.warn(pos, msg)
}
OK
}
if (immediate) {
action()
} else {
unit.toCheck += action
true
}
}
def checkExistentialsFeature(pos: Position, tpe: Type, prefix: String) = tpe match {
case extp: ExistentialType if !extp.isRepresentableWithWildcards =>
checkFeature(pos, 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
* (4.2) otherwise, if `pt` is a function type and method is not a constructor,
* convert to function by eta-expansion,
* (4.3) otherwise, if the method is nullary with a result type compatible to `pt`
* and it is not a constructor, apply it to ()
* 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, apply a view
* If all this fails, error
*/
protected def adapt(tree: Tree, mode: Int, pt: Type, original: Tree = EmptyTree): Tree = {
def adaptToImplicitMethod(mt: MethodType): Tree = {
if (context.undetparams.nonEmpty) { // (9) -- should revisit dropped condition `(mode & POLYmode) == 0`
// 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.hasErrors)
return setError(tree)
withCondConstrTyper(treeInfo.isSelfOrSuperConstrCall(tree)){ typer1 =>
if (original != EmptyTree && pt != WildcardType)
typer1.silent(tpr => {
val withImplicitArgs = tpr.applyImplicitArgs(tree)
if (tpr.context.hasErrors) tree // silent will wrap it in SilentTypeError anyway
else tpr.typed(withImplicitArgs, mode, pt)
}) match {
case SilentResultValue(result) =>
result
case _ =>
val resetTree = resetLocalAttrs(original)
debuglog(s"fallback on implicits: ${tree}/$resetTree")
val tree1 = typed(resetTree, mode, WildcardType)
// 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.tpe = pluginsTyped(tree1.tpe, this, tree1, mode, pt)
if (tree1.isEmpty) tree1 else adapt(tree1, mode, pt, EmptyTree)
}
else
typer1.typed(typer1.applyImplicitArgs(tree), mode, pt)
}
}
def instantiateToMethodType(mt: MethodType): Tree = {
val meth = tree match {
// a partial named application is a block (see comment in EtaExpansion)
case Block(_, tree1) => tree1.symbol
case _ => tree.symbol
}
if (!meth.isConstructor && !meth.isTermMacro && isFunctionType(pt)) { // (4.2)
debuglog("eta-expanding " + tree + ":" + tree.tpe + " to " + pt)
checkParamsConvertible(tree, tree.tpe)
val tree0 = etaExpand(context.unit, tree, this)
// println("eta "+tree+" ---> "+tree0+":"+tree0.tpe+" undet: "+context.undetparams+ " mode: "+Integer.toHexString(mode))
if (context.undetparams.nonEmpty) {
// #2624: need to infer type arguments for eta expansion of a polymorphic method
// context.undetparams contains clones of meth.typeParams (fresh ones were generated in etaExpand)
// need to run typer on tree0, since etaExpansion sets the tpe's of its subtrees to null
// can't type with the expected type, as we can't recreate the setup in (3) without calling typed
// (note that (3) does not call typed to do the polymorphic type instantiation --
// it is called after the tree has been typed with a polymorphic expected result type)
instantiate(typed(tree0, mode, WildcardType), mode, pt)
} else
typed(tree0, mode, pt)
} else if (!meth.isConstructor && mt.params.isEmpty) { // (4.3)
adapt(typed(Apply(tree, List()) setPos tree.pos), mode, pt, original)
} else if (context.implicitsEnabled) {
MissingArgsForMethodTpeError(tree, meth)
} else {
setError(tree)
}
}
def adaptType(): Tree = {
if (inFunMode(mode)) {
// todo. the commented line below makes sense for typechecking, say, TypeApply(Ident(`some abstract type symbol`), List(...))
// because otherwise Ident will have its tpe set to a TypeRef, not to a PolyType, and `typedTypeApply` will fail
// but this needs additional investigation, because it crashes t5228, gadts1 and maybe something else
// tree setType tree.tpe.normalize
tree
} else if (tree.hasSymbol && !tree.symbol.typeParams.isEmpty && !inHKMode(mode) &&
!(tree.symbol.isJavaDefined && context.unit.isJava)) { // (7)
// @M When not typing a higher-kinded type ((mode & HKmode) == 0)
// or raw type (tree.symbol.isJavaDefined && context.unit.isJava), 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?
MissingTypeParametersError(tree)
} else if ( // (7.1) @M: check kind-arity
// @M: removed check for tree.hasSymbol and replace tree.symbol by tree.tpe.symbol (TypeTree's must also be checked here, and they don't directly have a symbol)
(inHKMode(mode)) &&
// @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!)
!sameLength(tree.tpe.typeParams, pt.typeParams) &&
!(tree.tpe.typeSymbol == AnyClass ||
tree.tpe.typeSymbol == NothingClass ||
pt == WildcardType)) {
// Check that the actual kind arity (tree.symbol.typeParams.length) conforms to the expected
// kind-arity (pt.typeParams.length). Full checks are done in checkKindBounds in Infer.
// 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).
KindArityMismatchError(tree, pt)
} else tree match { // (6)
case TypeTree() => tree
case _ => TypeTree(tree.tpe) setOriginal tree
}
}
/**
* To deal with the type slack between actual (run-time) types and statically known types, for each abstract type T,
* reflect its variance as a skolem that is upper-bounded by T (covariant position), or lower-bounded by T (contravariant).
*
* Consider the following example:
*
* class AbsWrapperCov[+A]
* case class Wrapper[B](x: Wrapped[B]) extends AbsWrapperCov[B]
*
* def unwrap[T](x: AbsWrapperCov[T]): Wrapped[T] = x match {
* case Wrapper(wrapped) => // Wrapper's type parameter must not be assumed to be equal to T, it's *upper-bounded* by it
* wrapped // : Wrapped[_ <: T]
* }
*
* this method should type check if and only if Wrapped is covariant in its type parameter
*
* when inferring Wrapper's type parameter B from x's type AbsWrapperCov[T],
* we must take into account that x's actual type is AbsWrapperCov[Tactual] forSome {type Tactual <: T}
* as AbsWrapperCov is covariant in A -- in other words, we must not assume we know T exactly, all we know is its upper bound
*
* since method application is the only way to generate this slack between run-time and compile-time types (TODO: right!?),
* we can simply replace skolems that represent method type parameters as seen from the method's body
* by other skolems that are (upper/lower)-bounded by that type-parameter skolem
* (depending on the variance position of the skolem in the statically assumed type of the scrutinee, pt)
*
* see test/files/../t5189*.scala
*/
def adaptConstrPattern(): Tree = { // (5)
def hasUnapplyMember(tp: Type) = reallyExists(unapplyMember(tp))
val overloadedExtractorOfObject = tree.symbol filter (sym => hasUnapplyMember(sym.tpe))
// if the tree's symbol's type does not define an extractor, maybe the tree's type does
// this is the case when we encounter an arbitrary tree as the target of an unapply call (rather than something that looks like a constructor call)
// (for now, this only happens due to wrapClassTagUnapply, but when we support parameterized extractors, it will become more common place)
val extractor = overloadedExtractorOfObject orElse unapplyMember(tree.tpe)
if (extractor != NoSymbol) {
// if we did some ad-hoc overloading resolution, update the tree's symbol
// do not update the symbol if the tree's symbol's type does not define an unapply member
// (e.g. since it's some method that returns an object with an unapply member)
if (overloadedExtractorOfObject != NoSymbol)
tree setSymbol overloadedExtractorOfObject
tree.tpe match {
case OverloadedType(pre, alts) => tree.tpe = overloadedType(pre, alts filter (alt => hasUnapplyMember(alt.tpe)))