/* NSC -- new Scala compiler * Copyright 2005-2013 LAMP/EPFL * @author Martin Odersky */ package scala.tools.nsc package typechecker import scala.collection.mutable import scala.annotation.tailrec import scala.reflect.internal.util.shortClassOfInstance /** * @author Martin Odersky * @version 1.0 */ trait Contexts { self: Analyzer => import global._ import definitions.{ JavaLangPackage, ScalaPackage, PredefModule } import ContextMode._ object NoContext extends Context { outer = this enclClass = this enclMethod = this override def nextEnclosing(p: Context => Boolean): Context = this override def enclosingContextChain: List[Context] = Nil override def implicitss: List[List[ImplicitInfo]] = Nil override def toString = "NoContext" } private object RootImports { // Possible lists of root imports val javaList = JavaLangPackage :: Nil val javaAndScalaList = JavaLangPackage :: ScalaPackage :: Nil val completeList = JavaLangPackage :: ScalaPackage :: PredefModule :: Nil } def ambiguousImports(imp1: ImportInfo, imp2: ImportInfo) = LookupAmbiguous(s"it is imported twice in the same scope by\n$imp1\nand $imp2") def ambiguousDefnAndImport(owner: Symbol, imp: ImportInfo) = LookupAmbiguous(s"it is both defined in $owner and imported subsequently by \n$imp") private lazy val startContext = { NoContext.make( Template(List(), emptyValDef, List()) setSymbol global.NoSymbol setType global.NoType, rootMirror.RootClass, rootMirror.RootClass.info.decls) } private lazy val allUsedSelectors = mutable.Map[ImportInfo, Set[ImportSelector]]() withDefaultValue Set() private lazy val allImportInfos = mutable.Map[CompilationUnit, List[ImportInfo]]() withDefaultValue Nil def warnUnusedImports(unit: CompilationUnit) = { for (imps <- allImportInfos.remove(unit)) { for (imp <- imps.reverse.distinct) { val used = allUsedSelectors(imp) def isMask(s: ImportSelector) = s.name != nme.WILDCARD && s.rename == nme.WILDCARD imp.tree.selectors filterNot (s => isMask(s) || used(s)) foreach { sel => unit.warning(imp posOf sel, "Unused import") } } allUsedSelectors --= imps } } var lastAccessCheckDetails: String = "" /** List of symbols to import from in a root context. Typically that * is `java.lang`, `scala`, and [[scala.Predef]], in that order. Exceptions: * * - if option `-Yno-imports` is given, nothing is imported * - if the unit is java defined, only `java.lang` is imported * - if option `-Yno-predef` is given, if the unit body has an import of Predef * among its leading imports, or if the tree is [[scala.Predef]], `Predef` is not imported. */ protected def rootImports(unit: CompilationUnit): List[Symbol] = { assert(definitions.isDefinitionsInitialized, "definitions uninitialized") if (settings.noimports) Nil else if (unit.isJava) RootImports.javaList else if (settings.nopredef || treeInfo.noPredefImportForUnit(unit.body)) RootImports.javaAndScalaList else RootImports.completeList } def rootContext(unit: CompilationUnit): Context = rootContext(unit, EmptyTree, erasedTypes = false) def rootContext(unit: CompilationUnit, tree: Tree): Context = rootContext(unit, tree, erasedTypes = false) def rootContext(unit: CompilationUnit, tree: Tree, erasedTypes: Boolean): Context = { var sc = startContext for (sym <- rootImports(unit)) { sc = sc.makeNewImport(gen.mkWildcardImport(sym)) sc.depth += 1 } val c = sc.make(tree, unit = unit) if (erasedTypes) c.setThrowErrors() else c.setReportErrors() c(EnrichmentEnabled | ImplicitsEnabled) = !erasedTypes c } def resetContexts() { var sc = startContext while (sc != NoContext) { sc.tree match { case Import(qual, _) => qual setType singleType(qual.symbol.owner.thisType, qual.symbol) case _ => } sc = sc.outer } } class Context private[typechecker] { var unit: CompilationUnit = NoCompilationUnit var tree: Tree = _ // Tree associated with this context var owner: Symbol = NoSymbol // The current owner var scope: Scope = _ // The current scope var outer: Context = _ // The next outer context var enclClass: Context = _ // The next outer context whose tree is a // template or package definition @inline final def savingEnclClass[A](c: Context)(a: => A): A = { val saved = enclClass enclClass = c try a finally enclClass = saved } private var mode: ContextMode = ContextMode.DefaultMode def update(mask: ContextMode, value: Boolean) { mode = mode.set(value, mask) } def set(enable: ContextMode = NOmode, disable: ContextMode = NOmode): this.type = { mode = mode.set(true, enable).set(false, disable) this } def apply(mask: ContextMode): Boolean = mode.inAll(mask) var enclMethod: Context = _ // The next outer context whose tree is a method var variance: Variance = Variance.Invariant // Variance relative to enclosing class private var _undetparams: List[Symbol] = List() // Undetermined type parameters, // not inherited to child contexts var depth: Int = 0 var imports: List[ImportInfo] = List() // currently visible imports var openImplicits: List[(Type,Tree)] = List() // types for which implicit arguments // are currently searched // for a named application block (Tree) the corresponding NamedApplyInfo var namedApplyBlockInfo: Option[(Tree, NamedApplyInfo)] = None var prefix: Type = NoPrefix def inConstructorSuffix_=(value: Boolean) = this(ConstructorSuffix) = value def inConstructorSuffix = this(ConstructorSuffix) def returnsSeen_=(value: Boolean) = this(ReturnsSeen) = value def returnsSeen = this(ReturnsSeen) def inSelfSuperCall_=(value: Boolean) = this(SelfSuperCall) = value def inSelfSuperCall = this(SelfSuperCall) var diagnostic: List[String] = Nil // these messages are printed when issuing an error def implicitsEnabled_=(value: Boolean) = this(ImplicitsEnabled) = value def implicitsEnabled = this(ImplicitsEnabled) def macrosEnabled_=(value: Boolean) = this(MacrosEnabled) = value def macrosEnabled = this(MacrosEnabled) def enrichmentEnabled_=(value: Boolean) = this(EnrichmentEnabled) = value def enrichmentEnabled = this(EnrichmentEnabled) def checking_=(value: Boolean) = this(Checking) = value def checking = this(Checking) def retyping_=(value: Boolean) = this(ReTyping) = value def retyping = this(ReTyping) var savedTypeBounds: List[(Symbol, Type)] = List() // saved type bounds // for type parameters which are narrowed in a GADT var typingIndentLevel: Int = 0 def typingIndent = " " * typingIndentLevel var buffer: mutable.Set[AbsTypeError] = _ var warningsBuffer: mutable.Set[(Position, String)] = _ def enclClassOrMethod: Context = if ((owner eq NoSymbol) || (owner.isClass) || (owner.isMethod)) this else outer.enclClassOrMethod def enclosingCaseDef = nextEnclosing(_.tree.isInstanceOf[CaseDef]) def undetparamsString = if (undetparams.isEmpty) "" else undetparams.mkString("undetparams=", ", ", "") def undetparams = _undetparams def undetparams_=(ps: List[Symbol]) = { _undetparams = ps } def extractUndetparams() = { val tparams = undetparams undetparams = List() tparams } def errBuffer = buffer def hasErrors = buffer.nonEmpty def hasWarnings = warningsBuffer.nonEmpty def state: ContextMode = mode def restoreState(state0: ContextMode) = mode = state0 def reportErrors = this(ReportErrors) def bufferErrors = this(BufferErrors) def ambiguousErrors = this(AmbiguousErrors) def throwErrors = mode.inNone(ReportErrors | BufferErrors) def setReportErrors(): Unit = set(enable = ReportErrors | AmbiguousErrors, disable = BufferErrors) def setBufferErrors(): Unit = {set(enable = BufferErrors, disable = ReportErrors | AmbiguousErrors); warnIfBufferNotClean()} def setThrowErrors(): Unit = this(ReportErrors | AmbiguousErrors | BufferErrors) = false def setAmbiguousErrors(report: Boolean): Unit = this(AmbiguousErrors) = report private def warnIfBufferNotClean() { if (!bufferErrors && hasErrors) devWarning("When entering the buffer state, context has to be clean. Current buffer: " + buffer) } def updateBuffer(errors: mutable.Set[AbsTypeError]) = buffer ++= errors def condBufferFlush(removeP: AbsTypeError => Boolean) { val elems = buffer.filter(removeP) buffer --= elems } def flushBuffer() { buffer.clear() } def flushAndReturnBuffer(): mutable.Set[AbsTypeError] = { val current = buffer.clone() buffer.clear() current } def flushAndReturnWarningsBuffer(): mutable.Set[(Position, String)] = { val current = warningsBuffer.clone() warningsBuffer.clear() current } private def withMode[T](enabled: ContextMode = NOmode, disabled: ContextMode = NOmode)(op: => T): T = { val saved = mode set(enabled, disabled) try op finally mode = saved } def withImplicitsEnabled[T](op: => T): T = withMode(enabled = ImplicitsEnabled)(op) def withImplicitsDisabled[T](op: => T): T = withMode(disabled = ImplicitsEnabled | EnrichmentEnabled)(op) def withImplicitsDisabledAllowEnrichment[T](op: => T): T = withMode(enabled = EnrichmentEnabled, disabled = ImplicitsEnabled)(op) def withMacrosEnabled[T](op: => T): T = withMode(enabled = MacrosEnabled)(op) def withMacrosDisabled[T](op: => T): T = withMode(disabled = MacrosEnabled)(op) def make(tree: Tree = tree, owner: Symbol = owner, scope: Scope = scope, imports: List[ImportInfo] = imports, unit: CompilationUnit = unit): Context = { val c = new Context c.unit = unit c.tree = tree c.owner = owner c.scope = scope c.outer = this c.restoreState(this.state) // note: ConstructorSuffix conditionally overwritten below. val isTemplateOrPackage = tree match { case _: Template | _: PackageDef => true case _ => false } val isDefDef = tree match { case _: DefDef => true case _ => false } c.prefix = if (isTemplateOrPackage) c.owner.thisType else if (c.owner != this.owner && c.isLocal) NoPrefix else prefix c.enclClass = if (isTemplateOrPackage) c else enclClass c(ConstructorSuffix) = !isTemplateOrPackage && c(ConstructorSuffix) c.enclMethod = if (isDefDef) c else enclMethod c.variance = this.variance c.depth = this.depth + (if (scope == this.scope) 0 else 1) c.imports = imports c.diagnostic = this.diagnostic c.typingIndentLevel = typingIndentLevel c.openImplicits = this.openImplicits c.buffer = if (this.buffer == null) mutable.LinkedHashSet[AbsTypeError]() else this.buffer // need to initialize c.warningsBuffer = if (this.warningsBuffer == null) mutable.LinkedHashSet[(Position, String)]() else this.warningsBuffer registerContext(c.asInstanceOf[analyzer.Context]) debuglog("[context] ++ " + c.unit + " / " + tree.summaryString) c } def makeNewImport(imp: Import): Context = { val impInfo = new ImportInfo(imp, depth) if (settings.lint && imp.pos.isDefined) // pos.isDefined excludes java.lang/scala/Predef imports allImportInfos(unit) ::= impInfo make(imp, imports = impInfo :: imports) } def make(tree: Tree, owner: Symbol, scope: Scope): Context = // TODO Moving this optimization into the main overload of `make` causes all tests to fail. Why? if (tree == this.tree && owner == this.owner && scope == this.scope) this else make(tree, owner, scope, imports, unit) def makeNewScope(tree: Tree, owner: Symbol): Context = make(tree, owner, newNestedScope(scope)) def makeSilent(reportAmbiguousErrors: Boolean, newtree: Tree = tree): Context = { val c = make(newtree) c.setBufferErrors() c.setAmbiguousErrors(reportAmbiguousErrors) c.buffer = mutable.LinkedHashSet[AbsTypeError]() c } def makeImplicit(reportAmbiguousErrors: Boolean) = { val c = makeSilent(reportAmbiguousErrors) c(ImplicitsEnabled | EnrichmentEnabled) = false c } /** * A context for typing constructor parameter ValDefs, super or self invocation arguments and default getters * of constructors. These expressions need to be type checked in a scope outside the class, cf. spec 5.3.1. * * This method is called by namer / typer where `this` is the context for the constructor DefDef. The * owner of the resulting (new) context is the outer context for the Template, i.e. the context for the * ClassDef. This means that class type parameters will be in scope. The value parameters of the current * constructor are also entered into the new constructor scope. Members of the class however will not be * accessible. */ def makeConstructorContext = { val baseContext = enclClass.outer.nextEnclosing(!_.tree.isInstanceOf[Template]) val argContext = baseContext.makeNewScope(tree, owner) argContext.restoreState(state) argContext.inSelfSuperCall = true def enterElems(c: Context) { def enterLocalElems(e: ScopeEntry) { if (e != null && e.owner == c.scope) { enterLocalElems(e.next) argContext.scope enter e.sym } } if (c.isLocal && !c.owner.isLocalDummy) { enterElems(c.outer) enterLocalElems(c.scope.elems) } } // Enter the scope elements of this (the scope for the constructor DefDef) into the new constructor scope. // Concretely, this will enter the value parameters of constructor. enterElems(this) argContext } private def addDiagString(msg: String) = { val ds = if (diagnostic.isEmpty) "" else diagnostic.mkString("\n","\n", "") if (msg endsWith ds) msg else msg + ds } private def unitError(pos: Position, msg: String) = unit.error(pos, if (checking) "\n**** ERROR DURING INTERNAL CHECKING ****\n" + msg else msg) @inline private def issueCommon(err: AbsTypeError)(pf: PartialFunction[AbsTypeError, Unit]) { if (settings.Yissuedebug) { log("issue error: " + err.errMsg) (new Exception).printStackTrace() } if (pf isDefinedAt err) pf(err) else if (bufferErrors) { buffer += err } else throw new TypeError(err.errPos, err.errMsg) } def issue(err: AbsTypeError) { issueCommon(err) { case _ if reportErrors => unitError(err.errPos, addDiagString(err.errMsg)) } } def issueAmbiguousError(pre: Type, sym1: Symbol, sym2: Symbol, err: AbsTypeError) { issueCommon(err) { case _ if ambiguousErrors => if (!pre.isErroneous && !sym1.isErroneous && !sym2.isErroneous) unitError(err.errPos, err.errMsg) } } def issueAmbiguousError(err: AbsTypeError) { issueCommon(err) { case _ if ambiguousErrors => unitError(err.errPos, addDiagString(err.errMsg)) } } // TODO remove def error(pos: Position, err: Throwable) = if (reportErrors) unitError(pos, addDiagString(err.getMessage())) else throw err def error(pos: Position, msg: String) = { val msg1 = addDiagString(msg) if (reportErrors) unitError(pos, msg1) else throw new TypeError(pos, msg1) } def warning(pos: Position, msg: String): Unit = warning(pos, msg, force = false) def warning(pos: Position, msg: String, force: Boolean) { if (reportErrors || force) unit.warning(pos, msg) else if (bufferErrors) warningsBuffer += ((pos, msg)) } /** Is the owning symbol of this context a term? */ final def isLocal: Boolean = owner.isTerm def isNameInScope(name: Name) = lookupSymbol(name, _ => true).isSuccess // nextOuter determines which context is searched next for implicits // (after `this`, which contributes `newImplicits` below.) In // most cases, it is simply the outer context: if we're owned by // a constructor, the actual current context and the conceptual // context are different when it comes to scoping. The current // conceptual scope is the context enclosing the blocks which // represent the constructor body (TODO: why is there more than one // such block in the outer chain?) private def nextOuter = { // Drop the constructor body blocks, which come in varying numbers. // -- If the first statement is in the constructor, scopingCtx == (constructor definition) // -- Otherwise, scopingCtx == (the class which contains the constructor) val scopingCtx = if (owner.isConstructor) nextEnclosing(c => !c.tree.isInstanceOf[Block]) else this scopingCtx.outer } def nextEnclosing(p: Context => Boolean): Context = if (p(this)) this else outer.nextEnclosing(p) def enclosingContextChain: List[Context] = this :: outer.enclosingContextChain override def toString = "Context(%s@%s unit=%s scope=%s errors=%b, reportErrors=%b, throwErrors=%b)".format( owner.fullName, tree.shortClass, unit, scope.##, hasErrors, reportErrors, throwErrors ) /** Is `sub` a subclass of `base` or a companion object of such a subclass? */ def isSubClassOrCompanion(sub: Symbol, base: Symbol) = sub.isNonBottomSubClass(base) || sub.isModuleClass && sub.linkedClassOfClass.isNonBottomSubClass(base) /** Return the closest enclosing context that defines a subclass of `clazz` * or a companion object thereof, or `NoContext` if no such context exists. */ def enclosingSubClassContext(clazz: Symbol): Context = { var c = this.enclClass while (c != NoContext && !isSubClassOrCompanion(c.owner, clazz)) c = c.outer.enclClass c } /** Is `sym` accessible as a member of `pre` in current context? */ def isAccessible(sym: Symbol, pre: Type, superAccess: Boolean = false): Boolean = { lastAccessCheckDetails = "" // Console.println("isAccessible(%s, %s, %s)".format(sym, pre, superAccess)) def accessWithinLinked(ab: Symbol) = { val linked = ab.linkedClassOfClass // don't have access if there is no linked class // (before adding the `ne NoSymbol` check, this was a no-op when linked eq NoSymbol, // since `accessWithin(NoSymbol) == true` whatever the symbol) (linked ne NoSymbol) && accessWithin(linked) } /** Are we inside definition of `ab`? */ def accessWithin(ab: Symbol) = { // #3663: we must disregard package nesting if sym isJavaDefined if (sym.isJavaDefined) { // is `o` or one of its transitive owners equal to `ab`? // stops at first package, since further owners can only be surrounding packages @tailrec def abEnclosesStopAtPkg(o: Symbol): Boolean = (o eq ab) || (!o.isPackageClass && (o ne NoSymbol) && abEnclosesStopAtPkg(o.owner)) abEnclosesStopAtPkg(owner) } else (owner hasTransOwner ab) } def isSubThisType(pre: Type, clazz: Symbol): Boolean = pre match { case ThisType(pclazz) => pclazz isNonBottomSubClass clazz case _ => false } /* Is protected access to target symbol permitted */ def isProtectedAccessOK(target: Symbol) = { val c = enclosingSubClassContext(sym.owner) if (c == NoContext) lastAccessCheckDetails = "\n Access to protected "+target+" not permitted because"+ "\n "+"enclosing "+this.enclClass.owner+ this.enclClass.owner.locationString+" is not a subclass of "+ "\n "+sym.owner+sym.owner.locationString+" where target is defined" c != NoContext && { target.isType || { // allow accesses to types from arbitrary subclasses fixes #4737 val res = isSubClassOrCompanion(pre.widen.typeSymbol, c.owner) || c.owner.isModuleClass && isSubClassOrCompanion(pre.widen.typeSymbol, c.owner.linkedClassOfClass) if (!res) lastAccessCheckDetails = "\n Access to protected "+target+" not permitted because"+ "\n prefix type "+pre.widen+" does not conform to"+ "\n "+c.owner+c.owner.locationString+" where the access take place" res } } } (pre == NoPrefix) || { val ab = sym.accessBoundary(sym.owner) ( (ab.isTerm || ab == rootMirror.RootClass) || (accessWithin(ab) || accessWithinLinked(ab)) && ( !sym.hasLocalFlag || sym.owner.isImplClass // allow private local accesses to impl classes || sym.isProtected && isSubThisType(pre, sym.owner) || pre =:= sym.owner.thisType ) || sym.isProtected && ( superAccess || pre.isInstanceOf[ThisType] || phase.erasedTypes || (sym.overrideChain exists isProtectedAccessOK) // that last condition makes protected access via self types work. ) ) // note: phase.erasedTypes disables last test, because after addinterfaces // implementation classes are not in the superclass chain. If we enable the // test, bug780 fails. } } def pushTypeBounds(sym: Symbol) { sym.info match { case tb: TypeBounds => if (!tb.isEmptyBounds) log(s"Saving $sym info=$tb") case info => devWarning(s"Something other than a TypeBounds seen in pushTypeBounds: $info is a ${shortClassOfInstance(info)}") } savedTypeBounds ::= ((sym, sym.info)) } def restoreTypeBounds(tp: Type): Type = { def restore(): Type = savedTypeBounds.foldLeft(tp) { case (current, (sym, savedInfo)) => def bounds_s(tb: TypeBounds) = if (tb.isEmptyBounds) "" else s"TypeBounds(lo=${tb.lo}, hi=${tb.hi})" //@M TODO: when higher-kinded types are inferred, probably need a case PolyType(_, TypeBounds(...)) if ... => val TypeBounds(lo, hi) = sym.info.bounds val isUnique = lo <:< hi && hi <:< lo val isPresent = current contains sym def saved_s = bounds_s(savedInfo.bounds) def current_s = bounds_s(sym.info.bounds) if (isUnique && isPresent) devWarningResult(s"Preserving inference: ${sym.nameString}=$hi in $current (based on $current_s) before restoring $sym to saved $saved_s")( current.instantiateTypeParams(List(sym), List(hi)) ) else if (isPresent) devWarningResult(s"Discarding inferred $current_s because it does not uniquely determine $sym in")(current) else logResult(s"Discarding inferred $current_s because $sym does not appear in")(current) } try restore() finally { for ((sym, savedInfo) <- savedTypeBounds) sym setInfo debuglogResult(s"Discarding inferred $sym=${sym.info}, restoring saved info")(savedInfo) savedTypeBounds = Nil } } private var implicitsCache: List[List[ImplicitInfo]] = null private var implicitsRunId = NoRunId def resetCache() { implicitsRunId = NoRunId implicitsCache = null if (outer != null && outer != this) outer.resetCache() } /** A symbol `sym` qualifies as an implicit if it has the IMPLICIT flag set, * it is accessible, and if it is imported there is not already a local symbol * with the same names. Local symbols override imported ones. This fixes #2866. */ private def isQualifyingImplicit(name: Name, sym: Symbol, pre: Type, imported: Boolean) = sym.isImplicit && isAccessible(sym, pre) && !(imported && { val e = scope.lookupEntry(name) (e ne null) && (e.owner == scope) }) private def collectImplicits(syms: Scope, pre: Type, imported: Boolean = false): List[ImplicitInfo] = for (sym <- syms.toList if isQualifyingImplicit(sym.name, sym, pre, imported)) yield new ImplicitInfo(sym.name, pre, sym) private def collectImplicitImports(imp: ImportInfo): List[ImplicitInfo] = { val qual = imp.qual val pre = if (qual.tpe.typeSymbol.isPackageClass) // SI-6225 important if the imported symbol is inherited by the the package object. singleType(qual.tpe, qual.tpe member nme.PACKAGE) else qual.tpe def collect(sels: List[ImportSelector]): List[ImplicitInfo] = sels match { case List() => List() case List(ImportSelector(nme.WILDCARD, _, _, _)) => collectImplicits(pre.implicitMembers, pre, imported = true) case ImportSelector(from, _, to, _) :: sels1 => var impls = collect(sels1) filter (info => info.name != from) if (to != nme.WILDCARD) { for (sym <- importedAccessibleSymbol(imp, to).alternatives) if (isQualifyingImplicit(to, sym, pre, imported = true)) impls = new ImplicitInfo(to, pre, sym) :: impls } impls } //debuglog("collect implicit imports " + imp + "=" + collect(imp.tree.selectors))//DEBUG collect(imp.tree.selectors) } /* SI-5892 / SI-4270: `implicitss` can return results which are not accessible at the * point where implicit search is triggered. Example: implicits in (annotations of) * class type parameters (SI-5892). The `context.owner` is the class symbol, therefore * `implicitss` will return implicit conversions defined inside the class. These are * filtered out later by `eligibleInfos` (SI-4270 / 9129cfe9), as they don't type-check. */ def implicitss: List[List[ImplicitInfo]] = { if (implicitsRunId != currentRunId) { implicitsRunId = currentRunId implicitsCache = List() val newImplicits: List[ImplicitInfo] = if (owner != nextOuter.owner && owner.isClass && !owner.isPackageClass && !inSelfSuperCall) { if (!owner.isInitialized) return nextOuter.implicitss // debuglog("collect member implicits " + owner + ", implicit members = " + owner.thisType.implicitMembers)//DEBUG savingEnclClass(this) { // !!! In the body of `class C(implicit a: A) { }`, `implicitss` returns `List(List(a), List(a), List( isAccessible(s, imp1.qual.tpe, superAccess = false)) val imp2Symbol = (imp2 importedSymbol name).initialize filter (s => isAccessible(s, imp2.qual.tpe, superAccess = false)) // The types of the qualifiers from which the ambiguous imports come. // If the ambiguous name is a value, these must be the same. def t1 = imp1.qual.tpe def t2 = imp2.qual.tpe // The types of the ambiguous symbols, seen as members of their qualifiers. // If the ambiguous name is a monomorphic type, we can relax this far. def mt1 = t1 memberType imp1Symbol def mt2 = t2 memberType imp2Symbol def characterize = List( s"types: $t1 =:= $t2 ${t1 =:= t2} members: ${mt1 =:= mt2}", s"member type 1: $mt1", s"member type 2: $mt2" ).mkString("\n ") if (!ambiguous || !imp2Symbol.exists) Some(imp1) else if (!imp1Symbol.exists) Some(imp2) else ( // The symbol names are checked rather than the symbols themselves because // each time an overloaded member is looked up it receives a new symbol. // So foo.member("x") != foo.member("x") if x is overloaded. This seems // likely to be the cause of other bugs too... if (t1 =:= t2 && imp1Symbol.name == imp2Symbol.name) { log(s"Suppressing ambiguous import: $t1 =:= $t2 && $imp1Symbol == $imp2Symbol") Some(imp1) } // Monomorphism restriction on types is in part because type aliases could have the // same target type but attach different variance to the parameters. Maybe it can be // relaxed, but doesn't seem worth it at present. else if (mt1 =:= mt2 && name.isTypeName && imp1Symbol.isMonomorphicType && imp2Symbol.isMonomorphicType) { log(s"Suppressing ambiguous import: $mt1 =:= $mt2 && $imp1Symbol and $imp2Symbol are equivalent") Some(imp1) } else { log(s"Import is genuinely ambiguous:\n " + characterize) None } ) } /** The symbol with name `name` imported via the import in `imp`, * if any such symbol is accessible from this context. */ def importedAccessibleSymbol(imp: ImportInfo, name: Name): Symbol = importedAccessibleSymbol(imp, name, requireExplicit = false) private def importedAccessibleSymbol(imp: ImportInfo, name: Name, requireExplicit: Boolean): Symbol = imp.importedSymbol(name, requireExplicit) filter (s => isAccessible(s, imp.qual.tpe, superAccess = false)) /** Is `sym` defined in package object of package `pkg`? * Since sym may be defined in some parent of the package object, * we cannot inspect its owner only; we have to go through the * info of the package object. However to avoid cycles we'll check * what other ways we can before pushing that way. */ def isInPackageObject(sym: Symbol, pkg: Symbol): Boolean = { def uninitialized(what: String) = { log(s"Cannot look for $sym in package object of $pkg; $what is not initialized.") false } def pkgClass = if (pkg.isTerm) pkg.moduleClass else pkg def matchesInfo = ( // need to be careful here to not get a cyclic reference during bootstrap if (pkg.isInitialized) { val module = pkg.info member nme.PACKAGEkw if (module.isInitialized) module.info.member(sym.name).alternatives contains sym else uninitialized("" + module) } else uninitialized("" + pkg) ) def inPackageObject(sym: Symbol) = ( // To be in the package object, one of these must be true: // 1) sym.owner is a package object class, and sym.owner.owner is the package class for `pkg` // 2) sym.owner is inherited by the correct package object class // We try to establish 1) by inspecting the owners directly, and then we try // to rule out 2), and only if both those fail do we resort to looking in the info. !sym.isPackage && (sym.owner ne NoSymbol) && ( if (sym.owner.isPackageObjectClass) sym.owner.owner == pkgClass else !sym.owner.isPackageClass && matchesInfo ) ) // An overloaded symbol might not have the expected owner! // The alternatives must be inspected directly. pkgClass.isPackageClass && ( if (sym.isOverloaded) sym.alternatives forall (isInPackageObject(_, pkg)) else inPackageObject(sym) ) } /** Find the symbol of a simple name starting from this context. * All names are filtered through the "qualifies" predicate, * the search continuing as long as no qualifying name is found. */ def lookupSymbol(name: Name, qualifies: Symbol => Boolean): NameLookup = { var lookupError: NameLookup = null // set to non-null if a definite error is encountered var inaccessible: NameLookup = null // records inaccessible symbol for error reporting in case none is found var defSym: Symbol = NoSymbol // the directly found symbol var pre: Type = NoPrefix // the prefix type of defSym, if a class member var cx: Context = this // the context under consideration var symbolDepth: Int = -1 // the depth of the directly found symbol def finish(qual: Tree, sym: Symbol): NameLookup = ( if (lookupError ne null) lookupError else sym match { case NoSymbol if inaccessible ne null => inaccessible case NoSymbol => LookupNotFound case _ => LookupSucceeded(qual, sym) } ) def finishDefSym(sym: Symbol, pre0: Type): NameLookup = if (requiresQualifier(sym)) finish(gen.mkAttributedQualifier(pre0), sym) else finish(EmptyTree, sym) def isPackageOwnedInDifferentUnit(s: Symbol) = ( s.isDefinedInPackage && ( !currentRun.compiles(s) || unit.exists && s.sourceFile != unit.source.file ) ) def requiresQualifier(s: Symbol) = ( s.owner.isClass && !s.owner.isPackageClass && !s.isTypeParameterOrSkolem ) def lookupInPrefix(name: Name) = pre member name filter qualifies def accessibleInPrefix(s: Symbol) = isAccessible(s, pre, superAccess = false) def searchPrefix = { cx = cx.enclClass val found0 = lookupInPrefix(name) val found1 = found0 filter accessibleInPrefix if (found0.exists && !found1.exists && inaccessible == null) inaccessible = LookupInaccessible(found0, analyzer.lastAccessCheckDetails) found1 } def lookupInScope(scope: Scope) = (scope lookupUnshadowedEntries name filter (e => qualifies(e.sym))).toList def newOverloaded(owner: Symbol, pre: Type, entries: List[ScopeEntry]) = logResult(s"!!! lookup overloaded")(owner.newOverloaded(pre, entries map (_.sym))) // Constructor lookup should only look in the decls of the enclosing class // not in the self-type, nor in the enclosing context, nor in imports (SI-4460, SI-6745) if (name == nme.CONSTRUCTOR) return { val enclClassSym = cx.enclClass.owner val scope = cx.enclClass.prefix.baseType(enclClassSym).decls val constructorSym = lookupInScope(scope) match { case Nil => NoSymbol case hd :: Nil => hd.sym case entries => newOverloaded(enclClassSym, cx.enclClass.prefix, entries) } finishDefSym(constructorSym, cx.enclClass.prefix) } // cx.scope eq null arises during FixInvalidSyms in Duplicators while (defSym == NoSymbol && (cx ne NoContext) && (cx.scope ne null)) { pre = cx.enclClass.prefix defSym = lookupInScope(cx.scope) match { case Nil => searchPrefix case entries @ (hd :: tl) => // we have a winner: record the symbol depth symbolDepth = (cx.depth - cx.scope.nestingLevel) + hd.depth if (tl.isEmpty) hd.sym else newOverloaded(cx.owner, pre, entries) } if (!defSym.exists) cx = cx.outer // push further outward } if (symbolDepth < 0) symbolDepth = cx.depth var impSym: Symbol = NoSymbol var imports = Context.this.imports def imp1 = imports.head def imp2 = imports.tail.head def sameDepth = imp1.depth == imp2.depth def imp1Explicit = imp1 isExplicitImport name def imp2Explicit = imp2 isExplicitImport name def lookupImport(imp: ImportInfo, requireExplicit: Boolean) = importedAccessibleSymbol(imp, name, requireExplicit) filter qualifies // Java: A single-type-import declaration d in a compilation unit c of package p // that imports a type named n shadows, throughout c, the declarations of: // // 1) any top level type named n declared in another compilation unit of p // // A type-import-on-demand declaration never causes any other declaration to be shadowed. // // Scala: Bindings of different kinds have a precedence defined on them: // // 1) Definitions and declarations that are local, inherited, or made available by a // package clause in the same compilation unit where the definition occurs have // highest precedence. // 2) Explicit imports have next highest precedence. def depthOk(imp: ImportInfo) = ( imp.depth > symbolDepth || (unit.isJava && imp.isExplicitImport(name) && imp.depth == symbolDepth) ) while (!impSym.exists && imports.nonEmpty && depthOk(imports.head)) { impSym = lookupImport(imp1, requireExplicit = false) if (!impSym.exists) imports = imports.tail } if (defSym.exists && impSym.exists) { // imported symbols take precedence over package-owned symbols in different compilation units. if (isPackageOwnedInDifferentUnit(defSym)) defSym = NoSymbol // Defined symbols take precedence over erroneous imports. else if (impSym.isError || impSym.name == nme.CONSTRUCTOR) impSym = NoSymbol // Otherwise they are irreconcilably ambiguous else return ambiguousDefnAndImport(defSym.owner, imp1) } // At this point only one or the other of defSym and impSym might be set. if (defSym.exists) finishDefSym(defSym, pre) else if (impSym.exists) { // We continue walking down the imports as long as the tail is non-empty, which gives us: // imports == imp1 :: imp2 :: _ // And at least one of the following is true: // - imp1 and imp2 are at the same depth // - imp1 is a wildcard import, so all explicit imports from outer scopes must be checked def keepLooking = ( lookupError == null && imports.tail.nonEmpty && (sameDepth || !imp1Explicit) ) // If we find a competitor imp2 which imports the same name, possible outcomes are: // // - same depth, imp1 wild, imp2 explicit: imp2 wins, drop imp1 // - same depth, imp1 wild, imp2 wild: ambiguity check // - same depth, imp1 explicit, imp2 explicit: ambiguity check // - differing depth, imp1 wild, imp2 explicit: ambiguity check // - all others: imp1 wins, drop imp2 // // The ambiguity check is: if we can verify that both imports refer to the same // symbol (e.g. import foo.X followed by import foo._) then we discard imp2 // and proceed. If we cannot, issue an ambiguity error. while (keepLooking) { // If not at the same depth, limit the lookup to explicit imports. // This is desirable from a performance standpoint (compare to // filtering after the fact) but also necessary to keep the unused // import check from being misled by symbol lookups which are not // actually used. val other = lookupImport(imp2, requireExplicit = !sameDepth) def imp1wins() = { imports = imp1 :: imports.tail.tail } def imp2wins() = { impSym = other ; imports = imports.tail } if (!other.exists) // imp1 wins; drop imp2 and continue. imp1wins() else if (sameDepth && !imp1Explicit && imp2Explicit) // imp2 wins; drop imp1 and continue. imp2wins() else resolveAmbiguousImport(name, imp1, imp2) match { case Some(imp) => if (imp eq imp1) imp1wins() else imp2wins() case _ => lookupError = ambiguousImports(imp1, imp2) } } // optimization: don't write out package prefixes finish(resetPos(imp1.qual.duplicate), impSym) } else finish(EmptyTree, NoSymbol) } /** * Find a symbol in this context or one of its outers. * * Used to find symbols are owned by methods (or fields), they can't be * found in some scope. * * Examples: companion module of classes owned by a method, default getter * methods of nested methods. See NamesDefaults.scala */ def lookup(name: Name, expectedOwner: Symbol) = { var res: Symbol = NoSymbol var ctx = this while (res == NoSymbol && ctx.outer != ctx) { val s = ctx.scope lookup name if (s != NoSymbol && s.owner == expectedOwner) res = s else ctx = ctx.outer } res } } //class Context class ImportInfo(val tree: Import, val depth: Int) { def pos = tree.pos def posOf(sel: ImportSelector) = tree.pos withPoint sel.namePos /** The prefix expression */ def qual: Tree = tree.symbol.info match { case ImportType(expr) => expr case ErrorType => tree setType NoType // fix for #2870 case _ => throw new FatalError("symbol " + tree.symbol + " has bad type: " + tree.symbol.info) //debug } /** Is name imported explicitly, not via wildcard? */ def isExplicitImport(name: Name): Boolean = tree.selectors exists (_.rename == name.toTermName) /** The symbol with name `name` imported from import clause `tree`. */ def importedSymbol(name: Name): Symbol = importedSymbol(name, requireExplicit = false) private def recordUsage(sel: ImportSelector, result: Symbol) { def posstr = pos.source.file.name + ":" + posOf(sel).safeLine def resstr = if (tree.symbol.hasCompleteInfo) s"(qual=$qual, $result)" else s"(expr=${tree.expr}, ${result.fullLocationString})" debuglog(s"In $this at $posstr, selector '${selectorString(sel)}' resolved to $resstr") allUsedSelectors(this) += sel } /** If requireExplicit is true, wildcard imports are not considered. */ def importedSymbol(name: Name, requireExplicit: Boolean): Symbol = { var result: Symbol = NoSymbol var renamed = false var selectors = tree.selectors def current = selectors.head while (selectors.nonEmpty && result == NoSymbol) { if (current.rename == name.toTermName) result = qual.tpe.nonLocalMember( // new to address #2733: consider only non-local members for imports if (name.isTypeName) current.name.toTypeName else current.name) else if (current.name == name.toTermName) renamed = true else if (current.name == nme.WILDCARD && !renamed && !requireExplicit) result = qual.tpe.nonLocalMember(name) if (result == NoSymbol) selectors = selectors.tail } if (settings.lint && selectors.nonEmpty && result != NoSymbol && pos != NoPosition) recordUsage(current, result) // Harden against the fallout from bugs like SI-6745 // // [JZ] I considered issuing a devWarning and moving the // check inside the above loop, as I believe that // this always represents a mistake on the part of // the caller. if (definitions isImportable result) result else NoSymbol } private def selectorString(s: ImportSelector): String = { if (s.name == nme.WILDCARD && s.rename == null) "_" else if (s.name == s.rename) "" + s.name else s.name + " => " + s.rename } def allImportedSymbols: Iterable[Symbol] = importableMembers(qual.tpe) flatMap (transformImport(tree.selectors, _)) private def transformImport(selectors: List[ImportSelector], sym: Symbol): List[Symbol] = selectors match { case List() => List() case List(ImportSelector(nme.WILDCARD, _, _, _)) => List(sym) case ImportSelector(from, _, to, _) :: _ if from == sym.name => if (to == nme.WILDCARD) List() else List(sym.cloneSymbol(sym.owner, sym.rawflags, to)) case _ :: rest => transformImport(rest, sym) } override def hashCode = tree.## override def equals(other: Any) = other match { case that: ImportInfo => (tree == that.tree) case _ => false } override def toString = tree.toString } case class ImportType(expr: Tree) extends Type { override def safeToString = "ImportType("+expr+")" } } object ContextMode { private implicit def liftIntBitsToContextState(bits: Int): ContextMode = apply(bits) def apply(bits: Int): ContextMode = new ContextMode(bits) final val NOmode: ContextMode = 0 final val ReportErrors: ContextMode = 1 << 0 final val BufferErrors: ContextMode = 1 << 1 final val AmbiguousErrors: ContextMode = 1 << 2 /** Are we in a secondary constructor after the this constructor call? */ final val ConstructorSuffix: ContextMode = 1 << 3 /** For method context: were returns encountered? */ final val ReturnsSeen: ContextMode = 1 << 4 /** Is this context (enclosed in) a constructor call? * (the call to the super or self constructor in the first line of a constructor.) * In such a context, the object's fields should not be in scope */ final val SelfSuperCall: ContextMode = 1 << 5 // TODO harvest documentation for this final val ImplicitsEnabled: ContextMode = 1 << 6 final val MacrosEnabled: ContextMode = 1 << 7 /** To selectively allow enrichment in patterns, where other kinds of implicit conversions are not allowed */ final val EnrichmentEnabled: ContextMode = 1 << 8 /** Are we in a run of [[scala.tools.nsc.typechecker.TreeCheckers]]? */ final val Checking: ContextMode = 1 << 9 // TODO harvest documentation for this final val ReTyping: ContextMode = 1 << 10 final val DefaultMode: ContextMode = MacrosEnabled private val contextModeNameMap = Map( ReportErrors -> "ReportErrors", BufferErrors -> "BufferErrors", AmbiguousErrors -> "AmbiguousErrors", ConstructorSuffix -> "ConstructorSuffix", SelfSuperCall -> "SelfSuperCall", ImplicitsEnabled -> "ImplicitsEnabled", MacrosEnabled -> "MacrosEnabled", Checking -> "Checking", ReTyping -> "ReTyping" ) } /** * A value class to carry the boolean flags of a context, such as whether errors should * be buffered or reported. */ final class ContextMode private (val bits: Int) extends AnyVal { import ContextMode._ def &(other: ContextMode): ContextMode = new ContextMode(bits & other.bits) def |(other: ContextMode): ContextMode = new ContextMode(bits | other.bits) def &~(other: ContextMode): ContextMode = new ContextMode(bits & ~(other.bits)) def set(value: Boolean, mask: ContextMode) = if (value) |(mask) else &~(mask) def inAll(required: ContextMode) = (this & required) == required def inAny(required: ContextMode) = (this & required) != NOmode def inNone(prohibited: ContextMode) = (this & prohibited) == NOmode override def toString = if (bits == 0) "NOmode" else (contextModeNameMap filterKeys inAll).values.toList.sorted mkString " " }