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RefChecks.scala
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RefChecks.scala
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/*
* Scala (https://www.scala-lang.org)
*
* Copyright EPFL and Lightbend, Inc.
*
* Licensed under Apache License 2.0
* (http://www.apache.org/licenses/LICENSE-2.0).
*
* See the NOTICE file distributed with this work for
* additional information regarding copyright ownership.
*/
package scala.tools.nsc
package typechecker
import scala.collection.mutable
import scala.collection.mutable.ListBuffer
import scala.tools.nsc.Reporting.WarningCategory
import scala.tools.nsc.settings.ScalaVersion
import scala.tools.nsc.settings.NoScalaVersion
import symtab.Flags._
import transform.Transform
/** Post-attribution checking and transformation.
*
* This phase checks the following postconditions:
*
* - All overrides conform to rules.
* - All type arguments conform to bounds.
* - Every use of a type variable conforms to the variance annotation of that variable.
* - No forward reference to a term symbol extends beyond a value definition.
*
* It performs the following transformations:
*
* - Local modules are replaced by variables and classes.
* - Calls to case factory methods are replaced by new's.
* - Eliminate branches in a conditional if the condition is a constant.
*
* @author Martin Odersky
*/
abstract class RefChecks extends Transform {
val global: Global // need to repeat here because otherwise last mixin defines global as
// SymbolTable. If we had DOT this would not be an issue
import global._
import definitions._
import typer.typed
/** the following two members override abstract members in Transform */
val phaseName: String = "refchecks"
def newTransformer(unit: CompilationUnit): RefCheckTransformer =
new RefCheckTransformer(unit)
val toJavaRepeatedParam = SubstSymMap(RepeatedParamClass -> JavaRepeatedParamClass)
val toScalaRepeatedParam = SubstSymMap(JavaRepeatedParamClass -> RepeatedParamClass)
def accessFlagsToString(sym: Symbol) = flagsToString(
sym getFlag (PRIVATE | PROTECTED),
if (sym.hasAccessBoundary) "" + sym.privateWithin.name else ""
)
def overridesTypeInPrefix(tp1: Type, tp2: Type, prefix: Type): Boolean = (tp1.dealiasWiden, tp2.dealiasWiden) match {
case (MethodType(List(), rtp1), NullaryMethodType(rtp2)) => rtp1 <:< rtp2
case (NullaryMethodType(rtp1), MethodType(List(), rtp2)) => rtp1 <:< rtp2
case (TypeRef(_, sym, _), _) if sym.isModuleClass => overridesTypeInPrefix(NullaryMethodType(tp1), tp2, prefix)
case (_, TypeRef(_, sym, _)) if sym.isModuleClass => overridesTypeInPrefix(tp1, NullaryMethodType(tp2), prefix)
case _ => tp1 <:< tp2
}
private val separatelyCompiledScalaSuperclass = perRunCaches.newAnyRefMap[Symbol, Unit]()
final def isSeparatelyCompiledScalaSuperclass(sym: Symbol) = if (globalPhase.refChecked){
separatelyCompiledScalaSuperclass.contains(sym)
} else {
// conservative approximation in case someone in pre-refchecks phase asks for `exitingFields(someClass.info)`
// and we haven't run the refchecks tree transform which populates `separatelyCompiledScalaSuperclass`
false
}
class RefCheckTransformer(unit: CompilationUnit) extends AstTransformer {
var localTyper: analyzer.Typer = typer
var currentApplication: Tree = EmptyTree
var inAnnotation: Boolean = false
var inPattern: Boolean = false
@inline final def savingInPattern[A](body: => A): A = {
val saved = inPattern
try body finally inPattern = saved
}
// Track symbols of the refinement's parents and the base at which we've checked them,
// as well as the entire refinement type seen at that base.
// No need to check the same symbols again in a base that's a subclass of a previously checked base
private val checkedCombinations = mutable.Map[List[Symbol], (Symbol, Type)]()
private def notYetCheckedOrAdd(rt: RefinedType, currentBase: Symbol) = {
val seen = checkedCombinations.get(rt.parents.map(_.typeSymbol)).exists {
case (prevBase, prevTp) => currentBase.isSubClass(prevBase) && rt =:= prevTp.asSeenFrom(currentBase.thisType, prevBase)
}
if (!seen) checkedCombinations.addOne((rt.parents.map(_.typeSymbol), (currentBase, rt)))
!seen
}
private def refchecksWarning(pos: Position, msg: String, cat: WarningCategory): Unit =
runReporting.warning(pos, msg, cat, currentOwner)
// only one overloaded alternative is allowed to define default arguments
private def checkOverloadedRestrictions(clazz: Symbol, defaultClass: Symbol): Unit = {
// Using the default getters (such as methodName$default$1) as a cheap way of
// finding methods with default parameters. This way, we can limit the members to
// those with the DEFAULTPARAM flag, and infer the methods. Looking for the methods
// directly requires inspecting the parameter list of every one. That modification
// shaved 95% off the time spent in this method.
val defaultGetters = defaultClass.info.findMembers(excludedFlags = PARAM, requiredFlags = DEFAULTPARAM)
val defaultMethodNames = defaultGetters map (sym => nme.defaultGetterToMethod(sym.name))
defaultMethodNames.toList.distinct foreach { name =>
val methods = clazz.info.findMember(name, 0L, requiredFlags = METHOD, stableOnly = false).alternatives
def hasDefaultParam(tpe: Type): Boolean = tpe match {
case MethodType(params, restpe) => (params exists (_.hasDefault)) || hasDefaultParam(restpe)
case _ => false
}
val haveDefaults = methods.filter(sym => mexists(sym.info.paramss)(_.hasDefault) && !nme.isProtectedAccessorName(sym.name))
if (haveDefaults.lengthCompare(1) > 0) {
val owners = haveDefaults map (_.owner)
// constructors of different classes are allowed to have defaults
if (haveDefaults.exists(x => !x.isConstructor) || owners.distinct.size < haveDefaults.size) {
reporter.error(clazz.pos,
"in "+ clazz +
", multiple overloaded alternatives of "+ haveDefaults.head +
" define default arguments" + (
if (owners.forall(_ == clazz)) "."
else ".\nThe members with defaults are defined in "+owners.map(_.fullLocationString).mkString("", " and ", ".")
)
)
}
}
}
// Check for doomed attempt to overload applyDynamic
if (clazz isSubClass DynamicClass) {
for ((_, m1 :: m2 :: _) <- (clazz.info member nme.applyDynamic).alternatives groupBy (_.typeParams.length)) {
reporter.error(m1.pos, "implementation restriction: applyDynamic cannot be overloaded except by methods with different numbers of type parameters, e.g. applyDynamic[T1](method: String)(arg: T1) and applyDynamic[T1, T2](method: String)(arg1: T1, arg2: T2)")
}
}
// This has become noisy with implicit classes.
if (settings.isDeveloper && settings.warnPolyImplicitOverload) {
clazz.info.decls.foreach(sym => if (sym.isImplicit && sym.typeParams.nonEmpty) {
// implicit classes leave both a module symbol and a method symbol as residue
val alts = clazz.info.decl(sym.name).alternatives filterNot (_.isModule)
if (alts.size > 1)
alts foreach (x => refchecksWarning(x.pos, "parameterized overloaded implicit methods are not visible as view bounds", WarningCategory.LintPolyImplicitOverload))
})
}
}
// Override checking ------------------------------------------------------------
/** Add bridges for vararg methods that extend Java vararg methods
*/
def addVarargBridges(clazz: Symbol): List[Tree] = {
// This is quite expensive, so attempt to skip it completely.
// Insist there at least be a java-defined ancestor which
// defines a varargs method. TODO: Find a cheaper way to exclude.
if (inheritsJavaVarArgsMethod(clazz)) {
log("Found java varargs ancestor in " + clazz.fullLocationString + ".")
val self = clazz.thisType
val bridges = new ListBuffer[Tree]
def varargBridge(member: Symbol, bridgetpe: Type): Tree = {
log(s"Generating varargs bridge for ${member.fullLocationString} of type $bridgetpe")
val newFlags = (member.flags | VBRIDGE) & ~PRIVATE
val bridge = member.cloneSymbolImpl(clazz, newFlags) setPos clazz.pos
bridge.setInfo(bridgetpe.cloneInfo(bridge))
clazz.info.decls enter bridge
val params = bridge.paramss.head
val elemtp = params.last.tpe.typeArgs.head
val idents = params map Ident
val lastarg = gen.wildcardStar(gen.mkWrapVarargsArray(idents.last, elemtp))
val body = Apply(Select(This(clazz), member), idents.init :+ lastarg)
localTyper typed DefDef(bridge, body)
}
// For all concrete non-private members (but: see below) that have a (Scala) repeated
// parameter: compute the corresponding method type `jtpe` with a Java repeated parameter
// if a method with type `jtpe` exists and that method is not a varargs bridge
// then create a varargs bridge of type `jtpe` that forwards to the
// member method with the Scala vararg type.
//
// @PP: Can't call nonPrivateMembers because we will miss refinement members,
// which have been marked private. See scala/bug#4729.
for (member <- nonTrivialMembers(clazz)) {
log(s"Considering $member for java varargs bridge in $clazz")
if (!member.isDeferred && member.isMethod && hasRepeatedParam(member.info)) {
val inherited = clazz.info.nonPrivateMemberAdmitting(member.name, VBRIDGE)
// Delaying calling memberType as long as possible
if (inherited.exists) {
val jtpe = toJavaRepeatedParam(self memberType member)
// this is a bit tortuous: we look for non-private members or bridges
// if we find a bridge everything is OK. If we find another member,
// we need to create a bridge
val inherited1 = inherited filter (sym => !(sym hasFlag VBRIDGE) && (self memberType sym matches jtpe))
if (inherited1.exists)
bridges += varargBridge(member, jtpe)
}
}
}
if (bridges.size > 0)
log(s"Adding ${bridges.size} bridges for methods extending java varargs.")
bridges.toList
}
else Nil
}
/** 1. Check all members of class `clazz` for overriding conditions.
* That is for overriding member M and overridden member O:
*
* 1.1. M must have the same or stronger access privileges as O.
* 1.2. O must not be final.
* 1.3. O is deferred, or M has `override` modifier.
* 1.4. If O is stable, then so is M.
* 1.6. If O is a type alias, then M is an alias of O.
* 1.7. If O is an abstract type then
* 1.7.1 either M is an abstract type, and M's bounds are sharper than O's bounds.
* or M is a type alias or class which conforms to O's bounds.
* 1.7.2 higher-order type arguments must respect bounds on higher-order type parameters -- @M
* (explicit bounds and those implied by variance annotations) -- @see checkKindBounds
* 1.8. If O and M are values, then
* 1.8.1 M's type is a subtype of O's type, or
* 1.8.2 M is of type []S, O is of type ()T and S <: T, or
* 1.8.3 M is of type ()S, O is of type []T and S <: T, or
* 1.9. If M is a macro def, O cannot be deferred unless there's a concrete method overriding O.
* 1.10. If M is not a macro def, O cannot be a macro def.
* 2. Check that only abstract classes have deferred members
* 3. Check that concrete classes do not have deferred definitions
* that are not implemented in a subclass.
* 4. Check that every member with an `override` modifier
* overrides some other member.
* 5. Check that the nested class do not shadow other nested classes from outer class's parent.
*/
private def checkAllOverrides(clazz: Symbol, typesOnly: Boolean = false): Unit = {
val self = clazz.thisType
case class MixinOverrideError(member: Symbol, msg: String)
val mixinOverrideErrors = new ListBuffer[MixinOverrideError]()
def printMixinOverrideErrors(): Unit = {
mixinOverrideErrors.toList match {
case List() =>
case List(MixinOverrideError(_, msg)) =>
reporter.error(clazz.pos, msg)
case MixinOverrideError(member, msg) :: others =>
val others1 = others.map(_.member.name.decode).filter(member.name.decode != _).distinct
reporter.error(
clazz.pos,
msg+(if (others1.isEmpty) ""
else ";\n other members with override errors are: "+(others1 mkString ", ")))
}
}
def infoString(sym: Symbol) = infoString0(sym, sym.owner != clazz)
def infoStringWithLocation(sym: Symbol) = infoString0(sym, true)
def infoString0(member: Symbol, showLocation: Boolean) = {
val location =
if (!showLocation) ""
else member.ownsString match {
case "" => ""
case s => s" (defined in $s)"
}
val macroStr = if (member.isTermMacro) "macro " else ""
macroStr + member.defStringSeenAs(self.memberInfo(member)) + location
}
/* Check that all conditions for overriding `other` by `member` of class `clazz` are met.
*
* TODO: error messages could really be improved, including how they are composed
*/
def checkOverride(pair: SymbolPair): Unit = {
import pair.{highType, lowType, highInfo, rootType}
val member = pair.low
val other = pair.high
val memberClass = member.owner
val otherClass = other.owner
// debuglog(s"Checking validity of ${member.fullLocationString} overriding ${other.fullLocationString}")
def noErrorType = !pair.isErroneous
def isRootOrNone(sym: Symbol) = sym != null && sym.isRoot || sym == NoSymbol
def isNeitherInClass = memberClass != clazz && otherClass != clazz
val indent = " "
def overriddenWithAddendum(msg: String, foundReq: Boolean = settings.isDebug): String = {
val isConcreteOverAbstract =
(otherClass isSubClass memberClass) && other.isDeferred && !member.isDeferred
val addendum =
if (isConcreteOverAbstract)
s";\n${indent}(note that ${infoStringWithLocation(other)} is abstract,\n" +
s"${indent}and is therefore overridden by concrete ${infoStringWithLocation(member)})"
else if (foundReq) {
def info(sym: Symbol) = self.memberInfo(sym) match { case tp if sym.isGetter || sym.isValue && !sym.isMethod => tp.resultType case tp => tp }
analyzer.foundReqMsg(info(member), info(other))
}
else ""
infoStringWithLocation(other) + (if (msg.isEmpty) "" else s"\n$indent") + msg + addendum
}
def emitOverrideError(fullmsg: String): Unit = {
if (memberClass == clazz) reporter.error(member.pos, fullmsg)
else mixinOverrideErrors += MixinOverrideError(member, fullmsg)
}
def overrideErrorWithMemberInfo(msg: String): Unit =
if (noErrorType) emitOverrideError(msg + "\n" + overriddenWithAddendum(if (member.owner == clazz) "" else s"with ${infoString(member)}"))
def overrideError(msg: String): Unit =
if (noErrorType) emitOverrideError(msg)
def overrideTypeError(): Unit = {
if (member.isModule && other.isModule)
overrideError(s"overriding ${other.fullLocationString} with ${member.fullLocationString}:\n" +
"an overriding object must conform to the overridden object's class bound" +
analyzer.foundReqMsg(pair.lowClassBound, pair.highClassBound))
else {
val needSameType = !other.isDeferred && other.isAliasType
val msg =
(if (member.owner == clazz) "" else s"with ${infoString(member)}") +
(if (needSameType) " (Equivalent type required when overriding a type alias.)" else "")
overrideError("incompatible type in overriding\n" + overriddenWithAddendum(msg, foundReq = !needSameType))
}
}
def overrideErrorConcreteMissingOverride() = {
if (isNeitherInClass && !(otherClass isSubClass memberClass))
emitOverrideError(sm"""|$clazz inherits conflicting members:
|$indent${infoStringWithLocation(other)} and
|$indent${infoStringWithLocation(member)}
|$indent(note: this can be resolved by declaring an `override` in $clazz.)""")
else
overrideErrorWithMemberInfo("`override` modifier required to override concrete member:")
}
def overrideAccessError(): Unit = {
val otherAccess = accessFlagsToString(other)
overrideError("weaker access privileges in overriding\n"+
overriddenWithAddendum(s"override should ${(if (otherAccess == "") "be public" else "at least be " + otherAccess)}"))
}
//Console.println(infoString(member) + " overrides " + infoString(other) + " in " + clazz);//DEBUG
/* Is the intersection between given two lists of overridden symbols empty? */
def intersectionIsEmpty(syms1: List[Symbol], syms2: List[Symbol]) =
!(syms1 exists (syms2 contains _))
if (memberClass == ObjectClass && otherClass == AnyClass) {} // skip -- can we have a mode of symbolpairs where this pair doesn't even appear?
else if (typesOnly) checkOverrideTypes()
else {
// o: public | protected | package-protected (aka java's default access)
// ^-may be overridden by member with access privileges-v
// m: public | public/protected | public/protected/package-protected-in-same-package-as-o
if (member.isPrivate) // (1.1)
overrideError("weaker access privileges in overriding\n"+
overriddenWithAddendum(s"override should not be private"))
// todo: align accessibility implication checking with isAccessible in Contexts
val ob = other.accessBoundary(memberClass)
val mb = member.accessBoundary(memberClass)
def isOverrideAccessOK = member.isPublic || { // member is public, definitely same or relaxed access
(!other.isProtected || member.isProtected) && // if o is protected, so is m
((!isRootOrNone(ob) && ob.hasTransOwner(mb)) || // m relaxes o's access boundary
(other.isJavaDefined && other.isProtected)) // overriding a protected java member, see #3946 #12349
}
if (!isOverrideAccessOK) {
overrideAccessError()
} else if (other.isClass) {
overrideErrorWithMemberInfo("class definitions cannot be overridden:")
} else if (!other.isDeferred && member.isClass) {
overrideErrorWithMemberInfo("classes can only override abstract types; cannot override:")
} else if (other.isEffectivelyFinal) { // (1.2)
overrideErrorWithMemberInfo("cannot override final member:")
} else {
// In Java, the OVERRIDE flag is implied
val memberOverrides = member.isAnyOverride || (member.isJavaDefined && !member.isDeferred)
// Concrete `other` requires `override` for `member`.
// Synthetic exclusion for (at least) default getters, fixes scala/bug#5178. We cannot assign the OVERRIDE flag to
// the default getter: one default getter might sometimes override, sometimes not. Example in comment on ticket.
if (!(memberOverrides || other.isDeferred) && !member.isSynthetic) {
overrideErrorConcreteMissingOverride()
} else if (other.isAbstractOverride && other.isIncompleteIn(clazz) && !member.isAbstractOverride) {
overrideErrorWithMemberInfo("`abstract override` modifiers required to override:")
}
else if (memberOverrides && (other hasFlag ACCESSOR) && !(other hasFlag STABLE | DEFERRED)) {
// TODO: this is not covered by the spec.
overrideErrorWithMemberInfo("mutable variable cannot be overridden:")
}
else if (memberOverrides &&
!(memberClass.thisType.baseClasses exists (_ isSubClass otherClass)) &&
!member.isDeferred && !other.isDeferred &&
intersectionIsEmpty(member.extendedOverriddenSymbols, other.extendedOverriddenSymbols)) {
overrideErrorWithMemberInfo("cannot override a concrete member without a third member that's overridden by both " +
"(this rule is designed to prevent accidental overrides)")
} else if (other.isStable && !member.isStable) { // (1.4)
overrideErrorWithMemberInfo("stable, immutable value required to override:")
} else if (member.isValue && member.isLazy &&
other.isValue && other.hasFlag(STABLE) && !(other.isDeferred || other.isLazy)) {
overrideErrorWithMemberInfo("concrete non-lazy value cannot be overridden:")
} else if (other.isValue && other.isLazy &&
member.isValue && !member.isLazy) {
overrideErrorWithMemberInfo("value must be lazy when overriding concrete lazy value:")
} else if (other.isDeferred && member.isTermMacro && member.extendedOverriddenSymbols.forall(_.isDeferred)) { // (1.9)
overrideErrorWithMemberInfo("macro cannot override abstract method:")
} else if (other.isTermMacro && !member.isTermMacro) { // (1.10)
overrideErrorWithMemberInfo("macro can only be overridden by another macro:")
} else {
checkOverrideTypes()
// Don't bother users with deprecations caused by classes they inherit.
// Only warn for the pair that has one leg in `clazz`.
if (clazz == memberClass) checkOverrideDeprecated()
def javaDetermined(sym: Symbol) = sym.isJavaDefined || isUniversalMember(sym)
if (!member.hasAttachment[NullaryOverrideAdapted.type]
&& other.paramss.isEmpty && !member.paramss.isEmpty
&& !javaDetermined(member) && !member.overrides.exists(javaDetermined)
) {
val msg = "method with a single empty parameter list overrides method without any parameter list"
if (currentRun.isScala3)
overrideErrorWithMemberInfo(msg)
else
refchecksWarning(member.pos, msg, WarningCategory.OtherNullaryOverride)
}
}
}
}
def checkOverrideAlias(): Unit = {
// Important: first check the pair has the same kind, since the substitution
// carries high's type parameter's bounds over to low, so that
// type equality doesn't consider potentially different bounds on low/high's type params.
// In b781e25afe this went from using memberInfo to memberType (now lowType/highType), tested by neg/override.scala.
// TODO: was that the right fix? it seems type alias's RHS should be checked by looking at the symbol's info
if (pair.sameKind && lowType.substSym(member.typeParams, other.typeParams) =:= highType) ()
else overrideTypeError() // (1.6)
}
def checkOverrideAbstractType(): Unit = {
if (!(highInfo.bounds containsType lowType)) { // (1.7.1)
overrideTypeError(); // todo: do an explaintypes with bounds here
explainTypes(_.bounds containsType _, highInfo, lowType)
}
// check overriding (abstract type --> abstract type or abstract type --> concrete type member (a type alias))
// making an abstract type member concrete is like passing a type argument
typer.infer.checkKindBounds(other :: Nil, lowType :: Nil, rootType, memberClass) match { // (1.7.2)
case Nil =>
case kindErrors =>
reporter.error(member.pos,
"The kind of " + member.keyString+" " + member.varianceString + member.nameString+
" does not conform to the expected kind of " + other.defString + other.locationString + "." +
kindErrors.toList.mkString("\n", ", ", ""))
}
// check a type alias's RHS corresponds to its declaration
// this overlaps somewhat with validateVariance
if (member.isAliasType) {
typer.infer.checkKindBounds(member :: Nil, lowType.normalize :: Nil, rootType, memberClass) match {
case Nil =>
case kindErrors =>
reporter.error(member.pos,
"The kind of the right-hand side "+lowType.normalize+" of " + member.keyString+" "+
member.varianceString + member.nameString+ " does not conform to its expected kind."+
kindErrors.toList.mkString("\n", ", ", ""))
}
}
else if (member.isAbstractType && lowType.isVolatile && !highInfo.upperBound.isVolatile)
overrideErrorWithMemberInfo("volatile type member cannot override type member with non-volatile upper bound:")
}
def checkOverrideTerm(): Unit = {
member.cookJavaRawInfo() // #11584, #11840
other.cookJavaRawInfo() // #2454
if (!overridesTypeInPrefix(lowType, highType, rootType)) { // 8
overrideTypeError()
explainTypes(lowType, highType)
}
if (member.isStable && !highType.isVolatile) {
if (lowType.isVolatile)
overrideErrorWithMemberInfo("member with volatile type cannot override member with non-volatile type:")
else lowType.normalize.resultType match {
case rt: RefinedType if !(rt =:= highType) && notYetCheckedOrAdd(rt, pair.base) =>
// might mask some inconsistencies -- check overrides
val tsym = rt.typeSymbol
if (tsym.pos == NoPosition) tsym setPos member.pos
checkAllOverrides(tsym, typesOnly = true)
case _ =>
}
}
}
def checkOverrideTypes(): Unit = {
if (other.isAliasType) checkOverrideAlias()
else if (other.isAbstractType) checkOverrideAbstractType()
else if (other.isTerm) checkOverrideTerm()
}
def checkOverrideDeprecated(): Unit = {
if (other.hasDeprecatedOverridingAnnotation && !(member.hasDeprecatedOverridingAnnotation || member.ownerChain.exists(_.isDeprecated))) {
val version = other.deprecatedOverridingVersion.getOrElse("")
val since = if (version.isEmpty) version else s" (since $version)"
val message = other.deprecatedOverridingMessage map (msg => s": $msg") getOrElse ""
val report = s"overriding ${other.fullLocationString} is deprecated$since$message"
runReporting.deprecationWarning(member.pos, other, member, report, version)
}
}
}
val opc = new overridingPairs.PairsCursor(clazz)
while (opc.hasNext) {
if (!opc.high.isClass)
checkOverride(opc.currentPair)
opc.next()
}
printMixinOverrideErrors()
// Verifying a concrete class has nothing unimplemented.
if (clazz.isConcreteClass && !typesOnly) {
val abstractErrors = ListBuffer.empty[String]
def abstractErrorMessage = abstractErrors.mkString("\n")
def abstractClassError(msg: String, supplement: String = "", mustBeMixin: Boolean = false): Unit = {
def prelude =
if (clazz.isAnonymousClass || clazz.isModuleClass) "object creation impossible."
else if (mustBeMixin) s"$clazz needs to be a mixin."
else s"$clazz needs to be abstract."
if (abstractErrors.isEmpty) abstractErrors += prelude
abstractErrors += msg
if (!supplement.isEmpty) abstractErrors += supplement
}
def javaErasedOverridingSym(sym: Symbol): Symbol =
clazz.tpe.nonPrivateMemberAdmitting(sym.name, BRIDGE).filter(other =>
!other.isDeferred && other.isJavaDefined && !sym.enclClass.isSubClass(other.enclClass) && {
// #3622: erasure operates on uncurried types --
// note on passing sym in both cases: only sym.isType is relevant for uncurry.transformInfo
// !!! erasure.erasure(sym, uncurry.transformInfo(sym, tp)) gives erroneous or inaccessible type - check whether that's still the case!
def uncurryAndErase(tp: Type) = erasure.erasure(sym)(uncurry.transformInfo(sym, tp))
val tp1 = uncurryAndErase(clazz.thisType.memberType(sym))
val tp2 = uncurryAndErase(clazz.thisType.memberType(other))
exitingErasure(tp1 matches tp2)
})
def ignoreDeferred(member: Symbol) =
(member.isAbstractType && !member.isFBounded) || (
// the test requires exitingErasure so shouldn't be
// done if the compiler has no erasure phase available
member.isJavaDefined
&& (currentRun.erasurePhase == NoPhase || javaErasedOverridingSym(member) != NoSymbol)
)
// 2. Check that only abstract classes have deferred members
def checkNoAbstractMembers(): Unit = {
val NoError = null.asInstanceOf[String]
val EmptyDiagnostic = ""
def diagnose(member: Symbol, accessors: List[Symbol]): String = {
val underlying = analyzer.underlyingSymbol(member) // TODO: don't use this method
// Give a specific error message for abstract vars based on why it fails:
// It could be unimplemented, have only one accessor, or be uninitialized.
val isMultiple = accessors.size > 1
if (accessors.exists(_.isSetter) || (member.isGetter && !isMultiple && member.setterIn(member.owner).exists)) {
if (member.isSetter && isMultiple) NoError // If both getter and setter are missing, squelch the setter error.
else if (member.isSetter) "an abstract var requires a setter in addition to the getter"
else if (member.isGetter && !isMultiple) "an abstract var requires a getter in addition to the setter"
else "variables need to be initialized to be defined"
}
else if (underlying.isMethod) {
// Highlight any member that nearly matches: same name and arity,
// but differs in one param or param list.
val abstractParamLists = underlying.paramLists
val matchingArity = clazz.tpe.nonPrivateMembersAdmitting(VBRIDGE).filter { m =>
!m.isDeferred &&
m.name == underlying.name &&
sameLength(m.paramLists, abstractParamLists) &&
sumSize(m.paramLists, 0) == sumSize(abstractParamLists, 0) &&
sameLength(m.tpe.typeParams, underlying.tpe.typeParams) &&
!(m.isJavaDefined && m.hasFlag(JAVA_DEFAULTMETHOD))
}
matchingArity match {
// So far so good: only one candidate method
case Scope(concrete) =>
val concreteParamLists = concrete.paramLists
val aplIter = abstractParamLists.iterator.flatten
val cplIter = concreteParamLists.iterator.flatten
def mismatch(apl: Symbol, cpl: Symbol): Option[(Type, Type)] =
if (apl.tpe.asSeenFrom(clazz.tpe, underlying.owner) =:= cpl.tpe) None else Some(apl.tpe -> cpl.tpe)
def missingImplicit = abstractParamLists.zip(concreteParamLists).exists {
case (abss, konkrete) => abss.headOption.exists(_.isImplicit) && !konkrete.headOption.exists(_.isImplicit)
}
val mismatches = mapFilter2(aplIter, cplIter)(mismatch).take(2).toList
mismatches match {
// Only one mismatched parameter: say something useful.
case (pa, pc) :: Nil =>
val abstractSym = pa.typeSymbol
val concreteSym = pc.typeSymbol
def subclassMsg(c1: Symbol, c2: Symbol) =
s": ${c1.fullLocationString} is a subclass of ${c2.fullLocationString}, but method parameter types must match exactly."
def wrongSig = {
val m = concrete
fullyInitializeSymbol(m)
m.defStringSeenAs(clazz.tpe_*.memberType(m))
}
val addendum =
if (abstractSym == concreteSym) {
if (underlying.isJavaDefined && pa.typeArgs.isEmpty && abstractSym.typeParams.nonEmpty)
s". To implement this raw type, use ${rawToExistential(pa)}"
else if (pa.prefix =:= pc.prefix)
": their type parameters differ"
else
": their prefixes (i.e., enclosing instances) differ"
}
else if (abstractSym.isSubClass(concreteSym)) subclassMsg(abstractSym, concreteSym)
else if (concreteSym.isSubClass(abstractSym)) subclassMsg(concreteSym, abstractSym)
else s" in `$wrongSig`"
s"$pa does not match $pc$addendum"
case Nil if missingImplicit => "overriding member must declare implicit parameter list" // other overriding gotchas
case _ => EmptyDiagnostic
}
case _ => EmptyDiagnostic
}
}
else EmptyDiagnostic
}
def emitErrors(missing: List[Symbol]): Unit = {
// Group missing members by the name of the underlying symbol, to consolidate getters and setters.
val byName = missing.groupBy(_.name.getterName)
// There may be 1 or more missing members declared in 1 or more parents.
// If a single parent, the message names it. Otherwise, missing members are grouped by declaring class.
val byOwner = missing.groupBy(_.owner).toList
val announceOwner = byOwner.size > 1
def membersStrings(members: List[Symbol]) =
members.sortBy(_.name).flatMap { m =>
val accessors = byName.getOrElse(m.name.getterName, Nil)
val diagnostic = diagnose(m, accessors)
if (diagnostic == NoError) Nil
else {
val s0a = infoString0(m, showLocation = false)
fullyInitializeSymbol(m)
val s0b = m.defString
val s1 = m.defStringSeenAs(clazz.tpe_*.memberType(m))
val implMsg = if (s1 != s0a) s"implements `$s0a`" else if (s1 != s0b) s"implements `$s0b`" else ""
val spacer = if (diagnostic.nonEmpty && implMsg.nonEmpty) "; " else ""
val comment = if (diagnostic.nonEmpty || implMsg.nonEmpty) s" // $implMsg$spacer$diagnostic" else ""
s"$s1 = ???$comment" :: Nil
}
}
var count = 0
val stubs =
byOwner.sortBy(_._1.name.toString).flatMap {
case (owner, members) =>
val ms = membersStrings(members) :+ ""
count += ms.size - 1
if (announceOwner) s"// Members declared in ${owner.fullName}" :: ms else ms
}.init.map(s => s" $s\n").mkString
val isMulti = count > 1
val singleParent = if (byOwner.size == 1 && byOwner.head._1 != clazz) s" member${if (isMulti) "s" else ""} of ${byOwner.head._1}" else ""
val line0 =
if (isMulti) s"Missing implementations for ${count}${val p = singleParent ; if (p.isEmpty) " members" else p}."
else s"Missing implementation${val p = singleParent ; if (p.isEmpty) p else s" for$p"}:"
abstractClassError(line0, supplement = stubs)
}
def filtered[A](it: Iterator[A])(p: A => Boolean)(q: A => Boolean): (List[A], List[A]) = {
var ps, qs: List[A] = Nil
while (it.hasNext) {
val a = it.next()
if (p(a)) ps ::= a
else if (q(a)) qs ::= a
}
(ps, qs)
}
// Avoid extra allocations with reverseIterator. Filter for abstract members of interest, and bad abstract override.
val (missing, abstractIncomplete): (List[Symbol], List[Symbol]) =
filtered(clazz.info.nonPrivateMembersAdmitting(VBRIDGE).reverseIterator)(m => m.isDeferred & !ignoreDeferred(m))(m => m.isAbstractOverride && m.isIncompleteIn(clazz))
if (missing.nonEmpty) emitErrors(missing)
// Check the remainder for invalid absoverride.
for (member <- abstractIncomplete) {
val explanation = member.superSymbolIn(clazz) match {
case NoSymbol => ", but no concrete implementation could be found in a base class"
case other => " and overrides incomplete superclass member\n" + infoString(other)
}
abstractClassError(s"${infoString(member)} is marked `abstract` and `override`$explanation", mustBeMixin = true)
}
} // end checkNoAbstractMembers
// 3. Check that concrete classes do not have deferred definitions
// that are not implemented in a subclass.
// Note that this is not the same as (2); In a situation like
//
// class C { def m: Int = 0}
// class D extends C { def m: Int }
//
// (3) is violated but not (2).
def checkNoAbstractDecls(bc: Symbol): Unit = {
for (decl <- bc.info.decls) {
if (decl.isDeferred && !ignoreDeferred(decl)) {
val impl = decl.matchingSymbol(clazz.thisType, admit = VBRIDGE)
if (impl == NoSymbol || decl.owner.isSubClass(impl.owner))
abstractClassError(s"No implementation found in a subclass for deferred declaration\n" +
s"${infoString(decl)}${analyzer.abstractVarMessage(decl)}")
}
}
if (bc.superClass hasFlag ABSTRACT)
checkNoAbstractDecls(bc.superClass)
}
checkNoAbstractMembers()
if (abstractErrors.isEmpty)
checkNoAbstractDecls(clazz)
if (abstractErrors.nonEmpty)
reporter.error(clazz.pos, abstractErrorMessage)
}
else if (clazz.isTrait && !(clazz isSubClass AnyValClass)) {
// For non-AnyVal classes, prevent abstract methods in interfaces that override
// final members in Object; see #4431
for (decl <- clazz.info.decls) {
// Have to use matchingSymbol, not a method involving overridden symbols,
// because the scala type system understands that an abstract method here does not
// override a concrete method in Object. The jvm, however, does not.
val overridden = decl.matchingSymbol(ObjectClass, ObjectTpe)
if (overridden.isFinal)
reporter.error(decl.pos, "trait cannot redefine final method from class AnyRef")
}
}
/* Returns whether there is a symbol declared in class `inclazz`
* (which must be different from `clazz`) whose name and type
* seen as a member of `class.thisType` matches `member`'s.
*/
def hasMatchingSym(inclazz: Symbol, member: Symbol): Boolean = {
val isVarargs = hasRepeatedParam(member.tpe)
lazy val varargsType = toJavaRepeatedParam(member.tpe)
def isSignatureMatch(sym: Symbol) = !sym.isTerm || {
val symtpe = clazz.thisType memberType sym
def matches(tp: Type) = tp matches symtpe
matches(member.tpe) || (isVarargs && matches(varargsType))
}
/* The rules for accessing members which have an access boundary are more
* restrictive in java than scala. Since java has no concept of package nesting,
* a member with "default" (package-level) access can only be accessed by members
* in the exact same package. Example:
*
* package a.b;
* public class JavaClass { void foo() { } }
*
* The member foo() can be accessed only from members of package a.b, and not
* nested packages like a.b.c. In the analogous scala class:
*
* package a.b
* class ScalaClass { private[b] def foo() = () }
*
* The member IS accessible to classes in package a.b.c. The javaAccessCheck logic
* is restricting the set of matching signatures according to the above semantics.
*/
def javaAccessCheck(sym: Symbol) = (
!inclazz.isJavaDefined // not a java defined member
|| !sym.hasAccessBoundary // no access boundary
|| sym.isProtected // marked protected in java, thus accessible to subclasses
|| sym.privateWithin == member.enclosingPackageClass // exact package match
)
def classDecls = inclazz.info.nonPrivateDecl(member.name)
def matchingSyms = classDecls filter (sym => isSignatureMatch(sym) && javaAccessCheck(sym))
(inclazz != clazz) && (matchingSyms != NoSymbol)
}
// 4. Check that every defined member with an `override` modifier overrides some other member.
for (member <- clazz.info.decls)
if (member.isAnyOverride && !(clazz.thisType.baseClasses exists (hasMatchingSym(_, member)))) {
// for (bc <- clazz.info.baseClasses.tail) Console.println("" + bc + " has " + bc.info.decl(member.name) + ":" + bc.info.decl(member.name).tpe);//DEBUG
val nonMatching: List[Symbol] = clazz.info.member(member.name).alternatives.filterNot(_.owner == clazz).filterNot(_.isFinal)
def issueError(suffix: String) = reporter.error(member.pos, member.toString() + " overrides nothing" + suffix)
nonMatching match {
case Nil =>
issueError("")
case ms =>
val superSigs = ms.map(m => m.defStringSeenAs(clazz.tpe memberType m)).mkString("\n")
issueError(s".\nNote: the super classes of ${member.owner} contain the following, non final members named ${member.name}:\n${superSigs}")
}
member resetFlag (OVERRIDE | ABSOVERRIDE) // Any Override
}
// 5. Check that the nested class do not shadow other nested classes from outer class's parent
def checkNestedClassShadow(): Unit =
if (clazz.isNestedClass && !clazz.isModuleClass) {
val overridden = clazz.owner.ancestors
.map(a => clazz.matchingSymbol(a, clazz.owner.thisType))
.filter(c => c.exists && c.isClass)
overridden foreach { sym2 =>
def msg(what: String) = s"shadowing a nested class of a parent is $what but $clazz shadows $sym2 defined in ${sym2.owner}; rename the class to something else"
if (currentRun.isScala3) reporter.error(clazz.pos, msg("unsupported"))
else runReporting.deprecationWarning(clazz.pos, clazz, currentOwner, msg("deprecated"), "2.13.2")
}
}
checkNestedClassShadow()
} // end checkAllOverrides
// Basetype Checking --------------------------------------------------------
/** <ol>
* <li> <!-- 1 -->
* Check that later type instances in the base-type sequence
* are subtypes of earlier type instances of the same mixin.
* </li>
* </ol>
*/
private def validateBaseTypes(clazz: Symbol): Unit = {
val seenParents = mutable.HashSet[Type]()
val seenTypes = new Array[List[Type]](clazz.info.baseTypeSeq.length)
for (i <- 0 until seenTypes.length)
seenTypes(i) = Nil
/* validate all base types of a class in reverse linear order. */
def register(tp: Type): Unit = {
// if (clazz.fullName.endsWith("Collection.Projection"))
// println("validate base type "+tp)
val baseClass = tp.typeSymbol
if (baseClass.isClass) {
if (!baseClass.isTrait && !baseClass.isJavaDefined && !currentRun.compiles(baseClass) && !separatelyCompiledScalaSuperclass.contains(baseClass))
separatelyCompiledScalaSuperclass.update(baseClass, ())
val index = clazz.info.baseTypeIndex(baseClass)
if (index >= 0) {
if (seenTypes(index) forall (tp1 => !(tp1 <:< tp)))
seenTypes(index) =
tp :: (seenTypes(index) filter (tp1 => !(tp <:< tp1)))
}
}
val remaining = tp.parents filterNot seenParents
seenParents ++= remaining
remaining foreach register
}
register(clazz.tpe)
for (i <- 0 until seenTypes.length) {
val baseClass = clazz.info.baseTypeSeq(i).typeSymbol
seenTypes(i) match {
case Nil =>
devWarning(s"base $baseClass not found in basetypes of $clazz. This might indicate incorrect caching of TypeRef#parents.")
case _ :: Nil =>
;// OK
case tp1 :: tp2 :: _ =>
reporter.error(clazz.pos, "illegal inheritance;\n " + clazz +
" inherits different type instances of " + baseClass +
":\n" + tp1 + " and " + tp2)
explainTypes(tp1, tp2)
explainTypes(tp2, tp1)
}
}
}
// Variance Checking --------------------------------------------------------
object varianceValidator extends VarianceValidator {
private def tpString(tp: Type) = tp match {
case ClassInfoType(parents, _, clazz) => "supertype "+intersectionType(parents, clazz.owner)
case _ => "type "+tp
}
override def issueVarianceError(base: Symbol, sym: Symbol, required: Variance, tpe: Type): Unit = {
reporter.error(base.pos,
s"${sym.variance} $sym occurs in $required position in ${tpString(tpe)} of $base")
}
}
// Forward reference checking ---------------------------------------------------
class LevelInfo(val outer: LevelInfo) {
val scope: Scope = if (outer eq null) newScope else newNestedScope(outer.scope)
var maxindex: Int = Int.MinValue
var refpos: Position = _
var refsym: Symbol = _
}
private var currentLevel: LevelInfo = null
private val symIndex = perRunCaches.newMap[Symbol, Int]()
private def pushLevel(): Unit = {
currentLevel = new LevelInfo(currentLevel)
}
private def popLevel(): Unit = {
currentLevel = currentLevel.outer
}
private def enterSyms(stats: List[Tree]): Unit = {
var index = -1
for (stat <- stats) {
index = index + 1
stat match {
case _ : MemberDef if stat.symbol.isLocalToBlock =>
currentLevel.scope.enter(stat.symbol)
symIndex(stat.symbol) = index
case _ =>
}
}
}
private def enterReference(pos: Position, sym: Symbol): Unit = {
if (sym.isLocalToBlock) {
val e = currentLevel.scope.lookupEntry(sym.name)
if ((e ne null) && sym == e.sym) {
var l = currentLevel
while (l.scope != e.owner) l = l.outer
val symindex = symIndex(sym)
if (l.maxindex < symindex) {
l.refpos = pos
l.refsym = sym
l.maxindex = symindex
}
}
}
}
// Comparison checking -------------------------------------------------------
object normalizeAll extends TypeMap {
def apply(tp: Type) = mapOver(tp).normalize
}
def checkImplicitViewOptionApply(pos: Position, fn: Tree, args: List[Tree]): Unit = if (settings.warnOptionImplicit) (fn, args) match {
case (tap@TypeApply(fun, targs), List(view: ApplyImplicitView)) if fun.symbol == currentRun.runDefinitions.Option_apply =>
refchecksWarning(pos, s"Suspicious application of an implicit view (${view.fun}) in the argument to Option.apply.", WarningCategory.LintOptionImplicit) // scala/bug#6567
case _ =>
}
private def isObjectOrAnyComparisonMethod(sym: Symbol) = sym match {
case Object_eq | Object_ne | Object_== | Object_!= | Any_== | Any_!= => true
case _ => false
}
/**
* Check the sensibility of using the given `equals` to compare `qual` and `other`.
*
* NOTE: I'm really not convinced by the logic here. I also think this would work better after erasure.
*/
private def checkSensibleEquals(pos: Position, qual: Tree, name: Name, sym: Symbol, other: Tree) = {
def isReferenceOp = sym == Object_eq || sym == Object_ne
def isNew(tree: Tree) = tree match {
case Function(_, _) | Apply(Select(New(_), nme.CONSTRUCTOR), _) => true
case _ => false
}
def underlyingClass(tp: Type): Symbol = {
val sym = tp.widen.typeSymbol
if (sym.isAbstractType) underlyingClass(sym.info.upperBound)
else sym
}
val actual = underlyingClass(other.tpe)
val receiver = underlyingClass(qual.tpe)
def onTrees[T](f: List[Tree] => T) = f(List(qual, other))
def onSyms[T](f: List[Symbol] => T) = f(List(receiver, actual))
// @MAT normalize for consistency in error message, otherwise only part is normalized due to use of `typeSymbol`
def typesString = s"${normalizeAll(qual.tpe.widen)} and ${normalizeAll(other.tpe.widen)}"
// TODO: this should probably be used in more type comparisons in checkSensibleEquals
def erasedClass(tp: Type) = erasure.javaErasure(tp).typeSymbol
/* Symbols which limit the warnings we can issue since they may be value types */
val couldBeAnything = Set[Symbol](ObjectClass, ComparableClass, SerializableClass)
def isMaybeValue(sym: Symbol): Boolean = couldBeAnything(erasedClass(sym.tpe))
// Whether def equals(other: Any) has known behavior: it is the default
// inherited from java.lang.Object, or it is a synthetically generated
// case equals. TODO - more cases are warnable if the target is a synthetic
// equals.
def isUsingWarnableEquals = {
val m = receiver.info.member(nme.equals_)
((m == Object_equals) || (m == Any_equals) || isMethodCaseEquals(m))
}
def isMethodCaseEquals(m: Symbol) = m.isSynthetic && m.owner.isCase
def isCaseEquals = isMethodCaseEquals(receiver.info.member(nme.equals_))
// Whether this == or != is one of those defined in Any/AnyRef or an overload from elsewhere.
def isUsingDefaultScalaOp = sym == Object_== || sym == Object_!= || sym == Any_== || sym == Any_!=
def haveSubclassRelationship = (actual isSubClass receiver) || (receiver isSubClass actual)
// Whether the operands+operator represent a warnable combo (assuming anyrefs)
// Looking for comparisons performed with ==/!= in combination with either an
// equals method inherited from Object or a case class synthetic equals (for