Scala example source code file (Contexts.scala)
The Contexts.scala Scala example source code/* NSC -- new Scala compiler
* Copyright 2005-2013 LAMP/EPFL
* @author Martin Odersky
*/
package scala.tools.nsc
package typechecker
import scala.collection.{ immutable, 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, ScalaXmlTopScope, ScalaXmlPackage }
import ContextMode._
protected def onTreeCheckerError(pos: Position, msg: String): Unit = ()
object NoContext
extends Context(EmptyTree, NoSymbol, EmptyScope, NoCompilationUnit,
null) { // We can't pass the uninitialized `this`. Instead, we treat null specially in `Context#outer`
enclClass = this
enclMethod = this
override val depth = 0
override def nextEnclosing(p: Context => Boolean): Context = this
override def enclosingContextChain: List[Context] = Nil
override def implicitss: List[List[ImplicitInfo]] = Nil
override def imports: List[ImportInfo] = Nil
override def firstImport: Option[ImportInfo] = None
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(), noSelfType, 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)) {
// SI-8258 Needed for the presentation compiler using -sourcepath, otherwise cycles can occur. See the commit
// message for this ticket for an example.
debuglog("Omitted import of Predef._ for " + unit)
RootImports.javaAndScalaList
}
else RootImports.completeList
}
def rootContext(unit: CompilationUnit, tree: Tree = EmptyTree, erasedTypes: Boolean = false): Context = {
val rootImportsContext = (startContext /: rootImports(unit))((c, sym) => c.make(gen.mkWildcardImport(sym)))
// there must be a scala.xml package when xml literals were parsed in this unit
if (unit.hasXml && ScalaXmlPackage == NoSymbol)
unit.error(unit.firstXmlPos, "To compile XML syntax, the scala.xml package must be on the classpath.\nPlease see http://docs.scala-lang.org/overviews/core/scala-2.11.html#scala-xml.")
// scala-xml needs `scala.xml.TopScope` to be in scope globally as `$scope`
// We detect `scala-xml` by looking for `scala.xml.TopScope` and
// inject the equivalent of `import scala.xml.{TopScope => $scope}`
val contextWithXML =
if (!unit.hasXml || ScalaXmlTopScope == NoSymbol) rootImportsContext
else rootImportsContext.make(gen.mkImport(ScalaXmlPackage, nme.TopScope, nme.dollarScope))
val c = contextWithXML.make(tree, unit = unit)
if (erasedTypes) c.setThrowErrors() else c.setReportErrors()
c(EnrichmentEnabled | ImplicitsEnabled) = !erasedTypes
c
}
def resetContexts() {
startContext.enclosingContextChain foreach { context =>
context.tree match {
case Import(qual, _) => qual setType singleType(qual.symbol.owner.thisType, qual.symbol)
case _ =>
}
context.reportBuffer.clearAll()
}
}
/**
* A motley collection of the state and loosely associated behaviour of the type checker.
* Each `Typer` has an associated context, and as it descends into the tree new `(Typer, Context)`
* pairs are spawned.
*
* Meet the crew; first the state:
*
* - A tree, symbol, and scope representing the focus of the typechecker
* - An enclosing context, `outer`.
* - The current compilation unit.
* - A variety of bits that track the current error reporting policy (more on this later);
* whether or not implicits/macros are enabled, whether we are in a self or super call or
* in a constructor suffix. These are represented as bits in the mask `contextMode`.
* - Some odds and ends: undetermined type pararameters of the current line of type inference;
* contextual augmentation for error messages, tracking of the nesting depth.
*
* And behaviour:
*
* - The central point for issuing errors and warnings from the typechecker, with a means
* to buffer these for use in 'silent' type checking, when some recovery might be possible.
* - `Context` is something of a Zipper for the tree were are typechecking: it `enclosingContextChain`
* is the path back to the root. This is exactly what we need to resolve names (`lookupSymbol`)
* and to collect in-scope implicit defintions (`implicitss`)
* Supporting these are `imports`, which represents all `Import` trees in in the enclosing context chain.
* - In a similar vein, we can assess accessiblity (`isAccessible`.)
*
* More on error buffering:
* When are type errors recoverable? In quite a few places, it turns out. Some examples:
* trying to type an application with/without the expected type, or with/without implicit views
* enabled. This is usually mediated by `Typer.silent`, `Inferencer#tryTwice`.
*
* Intially, starting from the `typer` phase, the contexts either buffer or report errors;
* afterwards errors are thrown. This is configured in `rootContext`. Additionally, more
* fine grained control is needed based on the kind of error; ambiguity errors are often
* suppressed during exploraratory typing, such as determining whether `a == b` in an argument
* position is an assignment or a named argument, when `Infererencer#isApplicableSafe` type checks
* applications with and without an expected type, or whtn `Typer#tryTypedApply` tries to fit arguments to
* a function type with/without implicit views.
*
* When the error policies entails error/warning buffering, the mutable [[ReportBuffer]] records
* everything that is issued. It is important to note, that child Contexts created with `make`
* "inherit" the very same `ReportBuffer` instance, whereas children spawned through `makeSilent`
* receive an separate, fresh buffer.
*
* @param tree Tree associated with this context
* @param owner The current owner
* @param scope The current scope
* @param _outer The next outer context.
*/
class Context private[typechecker](val tree: Tree, val owner: Symbol, val scope: Scope,
val unit: CompilationUnit, _outer: Context) {
private def outerIsNoContext = _outer eq null
final def outer: Context = if (outerIsNoContext) NoContext else _outer
/** The next outer context whose tree is a template or package definition */
var enclClass: Context = _
@inline private def savingEnclClass[A](c: Context)(a: => A): A = {
val saved = enclClass
enclClass = c
try a finally enclClass = saved
}
/** A bitmask containing all the boolean flags in a context, e.g. are implicit views enabled */
var contextMode: ContextMode = ContextMode.DefaultMode
/** Update all modes in `mask` to `value` */
def update(mask: ContextMode, value: Boolean) {
contextMode = contextMode.set(value, mask)
}
/** Set all modes in the mask `enable` to true, and all in `disable` to false. */
def set(enable: ContextMode = NOmode, disable: ContextMode = NOmode): this.type = {
contextMode = contextMode.set(true, enable).set(false, disable)
this
}
/** Is this context in all modes in the given `mask`? */
def apply(mask: ContextMode): Boolean = contextMode.inAll(mask)
/** The next outer context whose tree is a method */
var enclMethod: Context = _
/** Variance relative to enclosing class */
var variance: Variance = Variance.Invariant
private var _undetparams: List[Symbol] = List()
protected def outerDepth = if (outerIsNoContext) 0 else outer.depth
val depth: Int = {
val increasesDepth = isRootImport || outerIsNoContext || (outer.scope != scope)
( if (increasesDepth) 1 else 0 ) + outerDepth
}
/** The currently visible imports */
def imports: List[ImportInfo] = outer.imports
/** Equivalent to `imports.headOption`, but more efficient */
def firstImport: Option[ImportInfo] = outer.firstImport
def isRootImport: Boolean = false
/** Types for which implicit arguments are currently searched */
var openImplicits: List[OpenImplicit] = List()
/* For a named application block (`Tree`) the corresponding `NamedApplyInfo`. */
var namedApplyBlockInfo: Option[(Tree, NamedApplyInfo)] = None
var prefix: Type = NoPrefix
def inSuperInit_=(value: Boolean) = this(SuperInit) = value
def inSuperInit = this(SuperInit)
def inConstructorSuffix_=(value: Boolean) = this(ConstructorSuffix) = value
def inConstructorSuffix = this(ConstructorSuffix)
def inPatAlternative_=(value: Boolean) = this(PatternAlternative) = value
def inPatAlternative = this(PatternAlternative)
def starPatterns_=(value: Boolean) = this(StarPatterns) = value
def starPatterns = this(StarPatterns)
def returnsSeen_=(value: Boolean) = this(ReturnsSeen) = value
def returnsSeen = this(ReturnsSeen)
def inSelfSuperCall_=(value: Boolean) = this(SelfSuperCall) = value
def inSelfSuperCall = this(SelfSuperCall)
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)
def inSecondTry = this(SecondTry)
def inSecondTry_=(value: Boolean) = this(SecondTry) = value
def inReturnExpr = this(ReturnExpr)
def inTypeConstructorAllowed = this(TypeConstructorAllowed)
def defaultModeForTyped: Mode = if (inTypeConstructorAllowed) Mode.NOmode else Mode.EXPRmode
/** These messages are printed when issuing an error */
var diagnostic: List[String] = Nil
/** Saved type bounds for type parameters which are narrowed in a GADT. */
var savedTypeBounds: List[(Symbol, Type)] = List()
/** The next enclosing context (potentially `this`) that is owned by a class or method */
def enclClassOrMethod: Context =
if (!owner.exists || owner.isClass || owner.isMethod) this
else outer.enclClassOrMethod
/** The next enclosing context (potentially `this`) that has a `CaseDef` as a tree */
def enclosingCaseDef = nextEnclosing(_.tree.isInstanceOf[CaseDef])
/** ...or an Apply. */
def enclosingApply = nextEnclosing(_.tree.isInstanceOf[Apply])
def siteString = {
def what_s = if (owner.isConstructor) "" else owner.kindString
def where_s = if (owner.isClass) "" else "in " + enclClass.owner.decodedName
List(what_s, owner.decodedName, where_s) filterNot (_ == "") mkString " "
}
//
// Tracking undetermined type parameters for type argument inference.
//
def undetparamsString =
if (undetparams.isEmpty) ""
else undetparams.mkString("undetparams=", ", ", "")
/** Undetermined type parameters. See `Infer#{inferExprInstance, adjustTypeArgs}`. Not inherited to child contexts */
def undetparams: List[Symbol] = _undetparams
def undetparams_=(ps: List[Symbol]) = { _undetparams = ps }
/** Return and clear the undetermined type parameters */
def extractUndetparams(): List[Symbol] = {
val tparams = undetparams
undetparams = List()
tparams
}
/** Run `body` with this context with no undetermined type parameters, restore the original
* the original list afterwards.
* @param reportAmbiguous Should ambiguous errors be reported during evaluation of `body`?
*/
def savingUndeterminedTypeParams[A](reportAmbiguous: Boolean = ambiguousErrors)(body: => A): A = {
withMode() {
this(AmbiguousErrors) = reportAmbiguous
val saved = extractUndetparams()
try body
finally undetparams = saved
}
}
//
// Error reporting policies and buffer.
//
private var _reportBuffer: ReportBuffer = new ReportBuffer
/** A buffer for errors and warnings, used with `this.bufferErrors == true` */
def reportBuffer = _reportBuffer
/** Discard the current report buffer, and replace with an empty one */
def useFreshReportBuffer() = _reportBuffer = new ReportBuffer
/** Discard the current report buffer, and replace with `other` */
def restoreReportBuffer(other: ReportBuffer) = _reportBuffer = other
/** The first error, if any, in the report buffer */
def firstError: Option[AbsTypeError] = reportBuffer.firstError
def errors: Seq[AbsTypeError] = reportBuffer.errors
/** Does the report buffer contain any errors? */
def hasErrors = reportBuffer.hasErrors
def reportErrors = this(ReportErrors)
def bufferErrors = this(BufferErrors)
def ambiguousErrors = this(AmbiguousErrors)
def throwErrors = contextMode.inNone(ReportErrors | BufferErrors)
def setReportErrors(): Unit = set(enable = ReportErrors | AmbiguousErrors, disable = BufferErrors)
def setBufferErrors(): Unit = set(enable = BufferErrors, disable = ReportErrors | AmbiguousErrors)
def setThrowErrors(): Unit = this(ReportErrors | AmbiguousErrors | BufferErrors) = false
def setAmbiguousErrors(report: Boolean): Unit = this(AmbiguousErrors) = report
/** Append the given errors to the report buffer */
def updateBuffer(errors: Traversable[AbsTypeError]) = reportBuffer ++= errors
/** Clear all errors from the report buffer */
def flushBuffer() { reportBuffer.clearAllErrors() }
/** Return and clear all errors from the report buffer */
def flushAndReturnBuffer(): immutable.Seq[AbsTypeError] = {
val current = reportBuffer.errors
reportBuffer.clearAllErrors()
current
}
/** Issue and clear all warnings from the report buffer */
def flushAndIssueWarnings() {
reportBuffer.warnings foreach {
case (pos, msg) => unit.warning(pos, msg)
}
reportBuffer.clearAllWarnings()
}
//
// Temporary mode adjustment
//
@inline def withMode[T](enabled: ContextMode = NOmode, disabled: ContextMode = NOmode)(op: => T): T = {
val saved = contextMode
set(enabled, disabled)
try op
finally contextMode = saved
}
@inline final def withImplicitsEnabled[T](op: => T): T = withMode(enabled = ImplicitsEnabled)(op)
@inline final def withImplicitsDisabled[T](op: => T): T = withMode(disabled = ImplicitsEnabled | EnrichmentEnabled)(op)
@inline final def withImplicitsDisabledAllowEnrichment[T](op: => T): T = withMode(enabled = EnrichmentEnabled, disabled = ImplicitsEnabled)(op)
@inline final def withMacrosEnabled[T](op: => T): T = withMode(enabled = MacrosEnabled)(op)
@inline final def withMacrosDisabled[T](op: => T): T = withMode(disabled = MacrosEnabled)(op)
@inline final def withinStarPatterns[T](op: => T): T = withMode(enabled = StarPatterns)(op)
@inline final def withinSuperInit[T](op: => T): T = withMode(enabled = SuperInit)(op)
@inline final def withinSecondTry[T](op: => T): T = withMode(enabled = SecondTry)(op)
@inline final def withinPatAlternative[T](op: => T): T = withMode(enabled = PatternAlternative)(op)
/** TypeConstructorAllowed is enabled when we are typing a higher-kinded type.
* adapt should then check kind-arity based on the prototypical type's kind
* arity. Type arguments should not be inferred.
*/
@inline final def withinTypeConstructorAllowed[T](op: => T): T = withMode(enabled = TypeConstructorAllowed)(op)
/* TODO - consolidate returnsSeen (which seems only to be used by checkDead)
* and ReturnExpr.
*/
@inline final def withinReturnExpr[T](op: => T): T = {
enclMethod.returnsSeen = true
withMode(enabled = ReturnExpr)(op)
}
// See comment on FormerNonStickyModes.
@inline final def withOnlyStickyModes[T](op: => T): T = withMode(disabled = FormerNonStickyModes)(op)
/** @return true if the `expr` evaluates to true within a silent Context that incurs no errors */
@inline final def inSilentMode(expr: => Boolean): Boolean = {
withMode() { // withMode with no arguments to restore the mode mutated by `setBufferErrors`.
setBufferErrors()
try expr && !hasErrors
finally reportBuffer.clearAll()
}
}
//
// Child Context Creation
//
/**
* Construct a child context. The parent and child will share the report buffer.
* Compare with `makeSilent`, in which the child has a fresh report buffer.
*
* If `tree` is an `Import`, that import will be avaiable at the head of
* `Context#imports`.
*/
def make(tree: Tree = tree, owner: Symbol = owner,
scope: Scope = scope, unit: CompilationUnit = unit): Context = {
val isTemplateOrPackage = tree match {
case _: Template | _: PackageDef => true
case _ => false
}
val isDefDef = tree match {
case _: DefDef => true
case _ => false
}
val isImport = tree match {
// The guard is for SI-8403. It prevents adding imports again in the context created by
// `Namer#createInnerNamer`
case _: Import if tree != this.tree => true
case _ => false
}
val sameOwner = owner == this.owner
val prefixInChild =
if (isTemplateOrPackage) owner.thisType
else if (!sameOwner && owner.isTerm) NoPrefix
else prefix
// The blank canvas
val c = if (isImport)
new Context(tree, owner, scope, unit, this) with ImportContext
else
new Context(tree, owner, scope, unit, this)
// Fields that are directly propagated
c.variance = variance
c.diagnostic = diagnostic
c.openImplicits = openImplicits
c.contextMode = contextMode // note: ConstructorSuffix, a bit within `mode`, is conditionally overwritten below.
c._reportBuffer = reportBuffer
// Fields that may take on a different value in the child
c.prefix = prefixInChild
c.enclClass = if (isTemplateOrPackage) c else enclClass
c(ConstructorSuffix) = !isTemplateOrPackage && c(ConstructorSuffix)
// SI-8245 `isLazy` need to skip lazy getters to ensure `return` binds to the right place
c.enclMethod = if (isDefDef && !owner.isLazy) c else enclMethod
registerContext(c.asInstanceOf[analyzer.Context])
debuglog("[context] ++ " + c.unit + " / " + tree.summaryString)
c
}
def make(tree: Tree, owner: Symbol, scope: Scope): Context =
// TODO SI-7345 Moving this optimization into the main overload of `make` causes all tests to fail.
// even if it is extened to check that `unit == this.unit`. Why is this?
if (tree == this.tree && owner == this.owner && scope == this.scope) this
else make(tree, owner, scope, unit)
/** Make a child context that represents a new nested scope */
def makeNewScope(tree: Tree, owner: Symbol): Context =
make(tree, owner, newNestedScope(scope))
/** Make a child context that buffers errors and warnings into a fresh report buffer. */
def makeSilent(reportAmbiguousErrors: Boolean = ambiguousErrors, newtree: Tree = tree): Context = {
val c = make(newtree)
c.setBufferErrors()
c.setAmbiguousErrors(reportAmbiguousErrors)
c._reportBuffer = new ReportBuffer // A fresh buffer so as not to leak errors/warnings into `this`.
c
}
/** Make a silent child context does not allow implicits. Used to prevent chaining of implicit views. */
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.contextMode = contextMode
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.owner.isTerm && !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
}
//
// Error and warning issuance
//
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 =
if (checking) onTreeCheckerError(pos, msg) else unit.error(pos, msg)
@inline private def issueCommon(err: AbsTypeError)(pf: PartialFunction[AbsTypeError, Unit]) {
// TODO: are errors allowed to have pos == NoPosition??
// if not, Jason suggests doing: val pos = err.errPos.orElse( { devWarning("Que?"); context.tree.pos })
if (settings.Yissuedebug) {
log("issue error: " + err.errMsg)
(new Exception).printStackTrace()
}
if (pf isDefinedAt err) pf(err)
else if (bufferErrors) { reportBuffer += err }
else throw new TypeError(err.errPos, err.errMsg)
}
/** Issue/buffer/throw the given type error according to the current mode for error reporting. */
def issue(err: AbsTypeError) {
issueCommon(err) { case _ if reportErrors =>
unitError(err.errPos, addDiagString(err.errMsg))
}
}
/** Issue/buffer/throw the given implicit ambiguity error according to the current mode for error reporting. */
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)
}
}
/** Issue/buffer/throw the given implicit ambiguity error according to the current mode for error reporting. */
def issueAmbiguousError(err: AbsTypeError) {
issueCommon(err) { case _ if ambiguousErrors => unitError(err.errPos, addDiagString(err.errMsg)) }
}
/** Issue/throw the given `err` according to the current mode for error reporting. */
def error(pos: Position, err: Throwable) =
if (reportErrors) unitError(pos, addDiagString(err.getMessage()))
else throw err
/** Issue/throw the given error message according to the current mode for error reporting. */
def error(pos: Position, msg: String) = {
val msg1 = addDiagString(msg)
if (reportErrors) unitError(pos, msg1)
else throw new TypeError(pos, msg1)
}
/** Issue/throw the given error message according to the current mode for error reporting. */
def warning(pos: Position, msg: String, force: Boolean = false) {
if (reportErrors || force) unit.warning(pos, msg)
else if (bufferErrors) reportBuffer += (pos -> msg)
}
// 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
private def treeTruncated = tree.toString.replaceAll("\\s+", " ").lines.mkString("\\n").take(70)
private def treeIdString = if (settings.uniqid.value) "#" + System.identityHashCode(tree).toString.takeRight(3) else ""
private def treeString = tree match {
case x: Import => "" + x
case Template(parents, `noSelfType`, body) =>
val pstr = if ((parents eq null) || parents.isEmpty) "Nil" else parents mkString " "
val bstr = if (body eq null) "" else body.length + " stats"
s"""Template($pstr, _, $bstr)"""
case x => s"${tree.shortClass}${treeIdString}:${treeTruncated}"
}
override def toString =
sm"""|Context($unit) {
| owner = $owner
| tree = $treeString
| scope = ${scope.size} decls
| contextMode = $contextMode
| outer.owner = ${outer.owner}
|}"""
//
// Accessibility checking
//
/** Is `sub` a subclass of `base` or a companion object of such a subclass? */
private 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
}
def enclosingNonImportContext: Context = {
var c = this
while (c != NoContext && c.tree.isInstanceOf[Import])
c = c.outer
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))
// don't have access if there is no linked class (so exclude linkedClass=NoSymbol)
def accessWithinLinked(ab: Symbol) = {
val linked = linkedClassOfClassOf(ab, this)
linked.fold(false)(accessWithin)
}
/* 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.isLocalToThis
|| 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.
}
}
//
// Type bound management
//
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 ${shortClassOfInstance(info)}")
}
savedTypeBounds ::= ((sym, sym.info))
}
def restoreTypeBounds(tp: Type): Type = {
def restore(): Type = savedTypeBounds.foldLeft(tp) { case (current, (sym, savedInfo)) =>
def bounds_s(tb: TypeBounds) = if (tb.isEmptyBounds) "<empty bounds>" else s"TypeBounds(lo=${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
}
}
//
// Implicit collection
//
private var implicitsCache: 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]] = {
val nextOuter = this.nextOuter
def withOuter(is: List[ImplicitInfo]): List[List[ImplicitInfo]] =
is match {
case Nil => nextOuter.implicitss
case _ => is :: nextOuter.implicitss
}
val CycleMarker = NoRunId - 1
if (implicitsRunId == CycleMarker) {
debuglog(s"cycle while collecting implicits at owner ${owner}, probably due to an implicit without an explicit return type. Continuing with implicits from enclosing contexts.")
withOuter(Nil)
} else if (implicitsRunId != currentRunId) {
implicitsRunId = CycleMarker
implicits(nextOuter) match {
case None =>
implicitsRunId = NoRunId
withOuter(Nil)
case Some(is) =>
implicitsRunId = currentRunId
implicitsCache = is
withOuter(is)
}
}
else withOuter(implicitsCache)
}
/** @return None if a cycle is detected, or Some(infos) containing the in-scope implicits at this context */
private def implicits(nextOuter: Context): Option[List[ImplicitInfo]] = {
val imports = this.imports
if (owner != nextOuter.owner && owner.isClass && !owner.isPackageClass && !inSelfSuperCall) {
if (!owner.isInitialized) None
else savingEnclClass(this) {
// !!! In the body of `class C(implicit a: A) { }`, `implicitss` returns `List(List(a), List(a), List(<predef..)))`
// it handled correctly by implicit search, which considers the second `a` to be shadowed, but should be
// remedied nonetheless.
Some(collectImplicits(owner.thisType.implicitMembers, owner.thisType))
}
} else if (scope != nextOuter.scope && !owner.isPackageClass) {
debuglog("collect local implicits " + scope.toList)//DEBUG
Some(collectImplicits(scope, NoPrefix))
} else if (firstImport != nextOuter.firstImport) {
assert(imports.tail.headOption == nextOuter.firstImport, (imports, nextOuter.imports))
Some(collectImplicitImports(imports.head))
} else if (owner.isPackageClass) {
// the corresponding package object may contain implicit members.
Some(collectImplicits(owner.tpe.implicitMembers, owner.tpe))
} else Some(Nil)
}
//
// Imports and symbol lookup
//
/** It's possible that seemingly conflicting identifiers are
* identifiably the same after type normalization. In such cases,
* allow compilation to proceed. A typical example is:
* package object foo { type InputStream = java.io.InputStream }
* import foo._, java.io._
*/
private def resolveAmbiguousImport(name: Name, imp1: ImportInfo, imp2: ImportInfo): Option[ImportInfo] = {
val imp1Explicit = imp1 isExplicitImport name
val imp2Explicit = imp2 isExplicitImport name
val ambiguous = if (imp1.depth == imp2.depth) imp1Explicit == imp2Explicit else !imp1Explicit && imp2Explicit
val imp1Symbol = (imp1 importedSymbol name).initialize filter (s => 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.hasPackageFlag && sym.owner.exists && (
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)
)
}
def isNameInScope(name: Name) = lookupSymbol(name, _ => true).isSuccess
/** 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"overloaded symbol in $pre")(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.alternatives.head.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
/** A `Context` focussed on an `Import` tree */
trait ImportContext extends Context {
private val impInfo: ImportInfo = {
val info = new ImportInfo(tree.asInstanceOf[Import], outerDepth)
if (settings.warnUnusedImport && !isRootImport) // excludes java.lang/scala/Predef imports
allImportInfos(unit) ::= info
info
}
override final def imports = impInfo :: super.imports
override final def firstImport = Some(impInfo)
override final def isRootImport = !tree.pos.isDefined
override final def toString = super.toString + " with " + s"ImportContext { $impInfo; outer.owner = ${outer.owner} }"
}
/** A buffer for warnings and errors that are accumulated during speculative type checking. */
final class ReportBuffer {
type Error = AbsTypeError
type Warning = (Position, String)
private def newBuffer[A] = mutable.LinkedHashSet.empty[A] // Important to use LinkedHS for stable results.
// [JZ] Contexts, pre- the SI-7345 refactor, avoided allocating the buffers until needed. This
// is replicated here out of conservatism.
private var _errorBuffer: mutable.LinkedHashSet[Error] = _
private def errorBuffer = {if (_errorBuffer == null) _errorBuffer = newBuffer; _errorBuffer}
def errors: immutable.Seq[Error] = errorBuffer.toVector
private var _warningBuffer: mutable.LinkedHashSet[Warning] = _
private def warningBuffer = {if (_warningBuffer == null) _warningBuffer = newBuffer; _warningBuffer}
def warnings: immutable.Seq[Warning] = warningBuffer.toVector
def +=(error: AbsTypeError): this.type = {
errorBuffer += error
this
}
def ++=(errors: Traversable[AbsTypeError]): this.type = {
errorBuffer ++= errors
this
}
def +=(warning: Warning): this.type = {
warningBuffer += warning
this
}
def clearAll(): this.type = {
clearAllErrors(); clearAllWarnings();
}
def clearAllErrors(): this.type = {
errorBuffer.clear()
this
}
def clearErrors(removeF: PartialFunction[AbsTypeError, Boolean]): this.type = {
errorBuffer.retain(!PartialFunction.cond(_)(removeF))
this
}
def retainErrors(leaveF: PartialFunction[AbsTypeError, Boolean]): this.type = {
errorBuffer.retain(PartialFunction.cond(_)(leaveF))
this
}
def clearAllWarnings(): this.type = {
warningBuffer.clear()
this
}
def hasErrors = errorBuffer.nonEmpty
def firstError = errorBuffer.headOption
}
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).line
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 ne Nil) && 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.warnUnusedImport && 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
}
type ImportType = global.ImportType
val ImportType = global.ImportType
}
object ContextMode {
import scala.language.implicitConversions
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
/** Are we retypechecking arguments independently from the function applied to them? See `Typer.tryTypedApply`
* TODO - iron out distinction/overlap with SecondTry.
*/
final val ReTyping: ContextMode = 1 << 10
/** Are we typechecking pattern alternatives. Formerly ALTmode. */
final val PatternAlternative: ContextMode = 1 << 11
/** Are star patterns allowed. Formerly STARmode. */
final val StarPatterns: ContextMode = 1 << 12
/** Are we typing the "super" in a superclass constructor call super.<init>. Formerly SUPERCONSTRmode. */
final val SuperInit: ContextMode = 1 << 13
/* Is this the second attempt to type this tree? In that case functions
* may no longer be coerced with implicit views. Formerly SNDTRYmode.
*/
final val SecondTry: ContextMode = 1 << 14
/** Are we in return position? Formerly RETmode. */
final val ReturnExpr: ContextMode = 1 << 15
/** Are unapplied type constructors allowed here? Formerly HKmode. */
final val TypeConstructorAllowed: ContextMode = 1 << 16
/** TODO: The "sticky modes" are EXPRmode, PATTERNmode, TYPEmode.
* To mimick the sticky mode behavior, when captain stickyfingers
* comes around we need to propagate those modes but forget the other
* context modes which were once mode bits; those being so far the
* ones listed here.
*/
final val FormerNonStickyModes: ContextMode = (
PatternAlternative | StarPatterns | SuperInit | SecondTry | ReturnExpr | TypeConstructorAllowed
)
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",
PatternAlternative -> "PatternAlternative",
StarPatterns -> "StarPatterns",
SuperInit -> "SuperInit",
SecondTry -> "SecondTry",
TypeConstructorAllowed -> "TypeConstructorAllowed"
)
}
/**
* 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 " "
}
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