/
RefChecks.scala
1854 lines (1681 loc) · 82.7 KB
/
RefChecks.scala
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/* NSC -- new Scala compiler
* Copyright 2005-2013 LAMP/EPFL
* @author Martin Odersky
*/
package scala.tools.nsc
package typechecker
import symtab.Flags._
import scala.collection.{ mutable, immutable }
import transform.InfoTransform
import scala.collection.mutable.ListBuffer
import scala.language.postfixOps
import scala.tools.nsc.settings.ScalaVersion
import scala.tools.nsc.settings.AnyScalaVersion
import scala.tools.nsc.settings.NoScalaVersion
/** <p>
* Post-attribution checking and transformation.
* </p>
* <p>
* This phase performs the following checks.
* </p>
* <ul>
* <li>All overrides conform to rules.</li>
* <li>All type arguments conform to bounds.</li>
* <li>All type variable uses conform to variance annotations.</li>
* <li>No forward reference to a term symbol extends beyond a value definition.</li>
* </ul>
* <p>
* It performs the following transformations.
* </p>
* <ul>
* <li>Local modules are replaced by variables and classes</li>
* <li>Calls to case factory methods are replaced by new's.</li>
* <li>Eliminate branches in a conditional if the condition is a constant</li>
* </ul>
*
* @author Martin Odersky
* @version 1.0
*
* @todo Check whether we always check type parameter bounds.
*/
abstract class RefChecks extends InfoTransform with scala.reflect.internal.transform.RefChecks {
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, typedOperator, atOwner}
/** the following two members override abstract members in Transform */
val phaseName: String = "refchecks"
override def phaseNewFlags: Long = lateMETHOD
def newTransformer(unit: CompilationUnit): RefCheckTransformer =
new RefCheckTransformer(unit)
override def changesBaseClasses = false
override def transformInfo(sym: Symbol, tp: Type): Type = {
if (sym.isModule && !sym.isStatic) sym setFlag (lateMETHOD | STABLE)
super.transformInfo(sym, tp)
}
val toJavaRepeatedParam = new SubstSymMap(RepeatedParamClass -> JavaRepeatedParamClass)
val toScalaRepeatedParam = new 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.normalize, tp2.normalize) 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 _ =>
def classBoundAsSeen(tp: Type) = tp.typeSymbol.classBound.asSeenFrom(prefix, tp.typeSymbol.owner)
(tp1 <:< tp2) || ( // object override check
tp1.typeSymbol.isModuleClass && tp2.typeSymbol.isModuleClass && {
val cb1 = classBoundAsSeen(tp1)
val cb2 = classBoundAsSeen(tp2)
(cb1 <:< cb2) && {
log("Allowing %s to override %s because %s <:< %s".format(tp1, tp2, cb1, cb2))
true
}
}
)
}
class RefCheckTransformer(unit: CompilationUnit) extends Transformer {
var localTyper: analyzer.Typer = typer;
var currentApplication: Tree = EmptyTree
var inPattern: Boolean = false
var checkedCombinations = Set[List[Type]]()
// only one overloaded alternative is allowed to define default arguments
private def checkOverloadedRestrictions(clazz: 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 = clazz.info.findMembers(0L, DEFAULTPARAM)
val defaultMethodNames = defaultGetters map (sym => nme.defaultGetterToMethod(sym.name))
defaultMethodNames.toList.distinct foreach { name =>
val methods = clazz.info.findMember(name, 0L, METHOD, 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 => hasDefaultParam(sym.info) && !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) {
unit.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 ", ".")
)
)
}
}
}
if (settings.lint.value) {
clazz.info.decls filter (x => x.isImplicit && x.typeParams.nonEmpty) foreach { sym =>
// 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 => unit.warning(x.pos, "parameterized overloaded implicit methods are not visible as view bounds"))
}
}
}
// 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 | ARTIFACT) & ~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.mkWrapArray(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 SI-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 ne NoSymbol) {
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.
* // @M: LIFTED 1.5. Neither M nor O are a parameterized type alias
* 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.
*/
private def checkAllOverrides(clazz: Symbol, typesOnly: Boolean = false) {
val self = clazz.thisType
def classBoundAsSeen(tp: Type) = {
tp.typeSymbol.classBound.asSeenFrom(self, tp.typeSymbol.owner)
}
case class MixinOverrideError(member: Symbol, msg: String)
var mixinOverrideErrors = new ListBuffer[MixinOverrideError]()
def printMixinOverrideErrors() {
mixinOverrideErrors.toList match {
case List() =>
case List(MixinOverrideError(_, msg)) =>
unit.error(clazz.pos, msg)
case MixinOverrideError(member, msg) :: others =>
val others1 = others.map(_.member.name.decode).filter(member.name.decode != _).distinct
unit.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(sym: Symbol, showLocation: Boolean) = {
val sym1 = analyzer.underlyingSymbol(sym)
sym1.toString() +
(if (showLocation)
sym1.locationString +
(if (sym1.isAliasType) ", which equals "+self.memberInfo(sym1)
else if (sym1.isAbstractType) " with bounds"+self.memberInfo(sym1)
else if (sym1.isModule) ""
else if (sym1.isTerm) " of type "+self.memberInfo(sym1)
else "")
else "")
}
/** Check that all conditions for overriding `other` by `member`
* of class `clazz` are met.
*/
def checkOverride(member: Symbol, other: Symbol) {
debuglog("Checking validity of %s overriding %s".format(member.fullLocationString, other.fullLocationString))
def memberTp = self.memberType(member)
def otherTp = self.memberType(other)
def noErrorType = other.tpe != ErrorType && member.tpe != ErrorType
def isRootOrNone(sym: Symbol) = sym != null && sym.isRoot || sym == NoSymbol
def isNeitherInClass = (member.owner != clazz) && (other.owner != clazz)
def objectOverrideErrorMsg = (
"overriding " + other.fullLocationString + " with " + member.fullLocationString + ":\n" +
"an overriding object must conform to the overridden object's class bound" +
analyzer.foundReqMsg(classBoundAsSeen(member.tpe), classBoundAsSeen(other.tpe))
)
def overrideErrorMsg(msg: String): String = {
val isConcreteOverAbstract =
(other.owner isSubClass member.owner) && other.isDeferred && !member.isDeferred
val addendum =
if (isConcreteOverAbstract)
";\n (Note that %s is abstract,\n and is therefore overridden by concrete %s)".format(
infoStringWithLocation(other),
infoStringWithLocation(member)
)
else if (settings.debug.value)
analyzer.foundReqMsg(member.tpe, other.tpe)
else ""
"overriding %s;\n %s %s%s".format(
infoStringWithLocation(other), infoString(member), msg, addendum
)
}
def emitOverrideError(fullmsg: String) {
if (member.owner == clazz) unit.error(member.pos, fullmsg)
else mixinOverrideErrors += new MixinOverrideError(member, fullmsg)
}
def overrideError(msg: String) {
if (noErrorType)
emitOverrideError(overrideErrorMsg(msg))
}
def overrideTypeError() {
if (noErrorType) {
emitOverrideError(
if (member.isModule && other.isModule) objectOverrideErrorMsg
else overrideErrorMsg("has incompatible type")
)
}
}
def overrideAccessError() {
val otherAccess = accessFlagsToString(other)
overrideError("has weaker access privileges; it should be "+ (if (otherAccess == "") "public" else "at least "+otherAccess))
}
//Console.println(infoString(member) + " overrides " + infoString(other) + " in " + clazz);//DEBUG
// return if we already checked this combination elsewhere
if (member.owner != clazz) {
def deferredCheck = member.isDeferred || !other.isDeferred
def subOther(s: Symbol) = s isSubClass other.owner
def subMember(s: Symbol) = s isSubClass member.owner
if (subOther(member.owner) && deferredCheck) {
//Console.println(infoString(member) + " shadows1 " + infoString(other) " in " + clazz);//DEBUG
return
}
if (clazz.parentSymbols exists (p => subOther(p) && subMember(p) && deferredCheck)) {
//Console.println(infoString(member) + " shadows2 " + infoString(other) + " in " + clazz);//DEBUG
return
}
if (clazz.parentSymbols forall (p => subOther(p) == subMember(p))) {
//Console.println(infoString(member) + " shadows " + infoString(other) + " in " + clazz);//DEBUG
return
}
}
/** Is the intersection between given two lists of overridden symbols empty?
*/
def intersectionIsEmpty(syms1: List[Symbol], syms2: List[Symbol]) =
!(syms1 exists (syms2 contains _))
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("has weaker access privileges; it should not be private")
// todo: align accessibility implication checking with isAccessible in Contexts
val ob = other.accessBoundary(member.owner)
val mb = member.accessBoundary(member.owner)
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) // overriding a protected java member, see #3946
}
if (!isOverrideAccessOK) {
overrideAccessError()
} else if (other.isClass) {
overrideError("cannot be used here - class definitions cannot be overridden");
} else if (!other.isDeferred && member.isClass) {
overrideError("cannot be used here - classes can only override abstract types");
} else if (other.isEffectivelyFinal) { // (1.2)
overrideError("cannot override final member");
} else if (!other.isDeferred && !other.hasFlag(DEFAULTMETHOD) && !member.isAnyOverride && !member.isSynthetic) { // (*)
// (*) Synthetic exclusion for (at least) default getters, fixes SI-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 (isNeitherInClass && !(other.owner isSubClass member.owner))
emitOverrideError(
clazz + " inherits conflicting members:\n "
+ infoStringWithLocation(other) + " and\n " + infoStringWithLocation(member)
+ "\n(Note: this can be resolved by declaring an override in " + clazz + ".)"
)
else
overrideError("needs `override' modifier")
} else if (other.isAbstractOverride && other.isIncompleteIn(clazz) && !member.isAbstractOverride) {
overrideError("needs `abstract override' modifiers")
}
else if (member.isAnyOverride && (other hasFlag ACCESSOR) && other.accessed.isVariable && !other.accessed.isLazy) {
// !?! this is not covered by the spec. We need to resolve this either by changing the spec or removing the test here.
// !!! is there a !?! convention? I'm !!!ing this to make sure it turns up on my searches.
if (!settings.overrideVars.value)
overrideError("cannot override a mutable variable")
}
else if (member.isAnyOverride &&
!(member.owner.thisType.baseClasses exists (_ isSubClass other.owner)) &&
!member.isDeferred && !other.isDeferred &&
intersectionIsEmpty(member.extendedOverriddenSymbols, other.extendedOverriddenSymbols)) {
overrideError("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)
overrideError("needs to be a stable, immutable value")
} else if (member.isValue && member.isLazy &&
other.isValue && !other.isSourceMethod && !other.isDeferred && !other.isLazy) {
overrideError("cannot override a concrete non-lazy value")
} else if (other.isValue && other.isLazy && !other.isSourceMethod && !other.isDeferred &&
member.isValue && !member.isLazy) {
overrideError("must be declared lazy to override a concrete lazy value")
} else if (other.isDeferred && member.isTermMacro && member.extendedOverriddenSymbols.forall(_.isDeferred)) { // (1.9)
overrideError("cannot override an abstract method")
} else if (other.isTermMacro && !member.isTermMacro) { // (1.10)
overrideError("cannot override a macro")
} else {
checkOverrideTypes()
checkOverrideDeprecated()
if (settings.warnNullaryOverride.value) {
if (other.paramss.isEmpty && !member.paramss.isEmpty) {
unit.warning(member.pos, "non-nullary method overrides nullary method")
}
}
}
}
def checkOverrideTypes() {
if (other.isAliasType) {
//if (!member.typeParams.isEmpty) (1.5) @MAT
// overrideError("may not be parameterized");
//if (!other.typeParams.isEmpty) (1.5) @MAT
// overrideError("may not override parameterized type");
// @M: substSym
if( !(sameLength(member.typeParams, other.typeParams) && (memberTp.substSym(member.typeParams, other.typeParams) =:= otherTp)) ) // (1.6)
overrideTypeError();
}
else if (other.isAbstractType) {
//if (!member.typeParams.isEmpty) // (1.7) @MAT
// overrideError("may not be parameterized");
val otherTp = self.memberInfo(other)
if (!(otherTp.bounds containsType memberTp)) { // (1.7.1)
overrideTypeError(); // todo: do an explaintypes with bounds here
explainTypes(_.bounds containsType _, otherTp, memberTp)
}
// 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
val kindErrors = typer.infer.checkKindBounds(List(other), List(memberTp), self, member.owner) // (1.7.2)
if(!kindErrors.isEmpty)
unit.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) {
// println("checkKindBounds" + ((List(member), List(memberTp.normalize), self, member.owner)))
val kindErrors = typer.infer.checkKindBounds(List(member), List(memberTp.normalize), self, member.owner)
if(!kindErrors.isEmpty)
unit.error(member.pos,
"The kind of the right-hand side "+memberTp.normalize+" of "+member.keyString+" "+
member.varianceString + member.nameString+ " does not conform to its expected kind."+
kindErrors.toList.mkString("\n", ", ", ""))
} else if (member.isAbstractType) {
if (memberTp.isVolatile && !otherTp.bounds.hi.isVolatile)
overrideError("is a volatile type; cannot override a type with non-volatile upper bound")
}
} else if (other.isTerm) {
other.cookJavaRawInfo() // #2454
val memberTp = self.memberType(member)
val otherTp = self.memberType(other)
if (!overridesTypeInPrefix(memberTp, otherTp, self)) { // 8
overrideTypeError()
explainTypes(memberTp, otherTp)
}
if (member.isStable && !otherTp.isVolatile) {
if (memberTp.isVolatile)
overrideError("has a volatile type; cannot override a member with non-volatile type")
else memberTp.normalize.resultType match {
case rt: RefinedType if !(rt =:= otherTp) && !(checkedCombinations contains rt.parents) =>
// might mask some inconsistencies -- check overrides
checkedCombinations += rt.parents
val tsym = rt.typeSymbol;
if (tsym.pos == NoPosition) tsym setPos member.pos
checkAllOverrides(tsym, typesOnly = true)
case _ =>
}
}
}
}
def checkOverrideDeprecated() {
if (other.hasDeprecatedOverridingAnnotation) {
val suffix = other.deprecatedOverridingMessage map (": " + _) getOrElse ""
val msg = s"overriding ${other.fullLocationString} is deprecated$suffix"
unit.deprecationWarning(member.pos, msg)
}
}
}
val opc = new overridingPairs.Cursor(clazz)
while (opc.hasNext) {
//Console.println(opc.overriding/* + ":" + opc.overriding.tpe*/ + " in "+opc.overriding.fullName + " overrides " + opc.overridden/* + ":" + opc.overridden.tpe*/ + " in "+opc.overridden.fullName + "/"+ opc.overridden.hasFlag(DEFERRED));//debug
if (!opc.overridden.isClass) checkOverride(opc.overriding, opc.overridden);
opc.next
}
printMixinOverrideErrors()
// Verifying a concrete class has nothing unimplemented.
if (clazz.isConcreteClass && !typesOnly) {
val abstractErrors = new ListBuffer[String]
def abstractErrorMessage =
// a little formatting polish
if (abstractErrors.size <= 2) abstractErrors mkString " "
else abstractErrors.tail.mkString(abstractErrors.head + ":\n", "\n", "")
def abstractClassError(mustBeMixin: Boolean, msg: String) {
def prelude = (
if (clazz.isAnonymousClass || clazz.isModuleClass) "object creation impossible"
else if (mustBeMixin) clazz + " needs to be a mixin"
else clazz + " needs to be abstract"
) + ", since"
if (abstractErrors.isEmpty) abstractErrors ++= List(prelude, msg)
else abstractErrors += msg
}
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 erreneous of 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))
afterErasure(tp1 matches tp2)
})
def ignoreDeferred(member: Symbol) = (
(member.isAbstractType && !member.isFBounded) || (
member.isJavaDefined &&
// the test requires afterErasure so shouldn't be
// done if the compiler has no erasure phase available
(currentRun.erasurePhase == NoPhase || javaErasedOverridingSym(member) != NoSymbol)
)
)
// 2. Check that only abstract classes have deferred members
def checkNoAbstractMembers(): Unit = {
// Avoid spurious duplicates: first gather any missing members.
def memberList = clazz.info.nonPrivateMembersAdmitting(VBRIDGE)
val (missing, rest) = memberList partition (m => m.isDeferred && !ignoreDeferred(m))
// Group missing members by the name of the underlying symbol,
// to consolidate getters and setters.
val grouped = missing groupBy (sym => analyzer.underlyingSymbol(sym).name)
val missingMethods = grouped.toList flatMap {
case (name, syms) =>
if (syms exists (_.isSetter)) syms filterNot (_.isGetter)
else syms
}
def stubImplementations: List[String] = {
// Grouping missing methods by the declaring class
val regrouped = missingMethods.groupBy(_.owner).toList
def membersStrings(members: List[Symbol]) =
members.sortBy("" + _.name) map (m => m.defStringSeenAs(clazz.tpe memberType m) + " = ???")
if (regrouped.tail.isEmpty)
membersStrings(regrouped.head._2)
else (regrouped.sortBy("" + _._1.name) flatMap {
case (owner, members) =>
("// Members declared in " + owner.fullName) +: membersStrings(members) :+ ""
}).init
}
// If there are numerous missing methods, we presume they are aware of it and
// give them a nicely formatted set of method signatures for implementing.
if (missingMethods.size > 1) {
abstractClassError(false, "it has " + missingMethods.size + " unimplemented members.")
val preface =
"""|/** As seen from %s, the missing signatures are as follows.
| * For convenience, these are usable as stub implementations.
| */
|""".stripMargin.format(clazz)
abstractErrors += stubImplementations.map(" " + _ + "\n").mkString(preface, "", "")
return
}
for (member <- missing) {
def undefined(msg: String) = abstractClassError(false, infoString(member) + " is not defined" + msg)
val underlying = analyzer.underlyingSymbol(member)
// Give a specific error message for abstract vars based on why it fails:
// It could be unimplemented, have only one accessor, or be uninitialized.
if (underlying.isVariable) {
val isMultiple = grouped.getOrElse(underlying.name, Nil).size > 1
// If both getter and setter are missing, squelch the setter error.
if (member.isSetter && isMultiple) ()
else undefined(
if (member.isSetter) "\n(Note that an abstract var requires a setter in addition to the getter)"
else if (member.isGetter && !isMultiple) "\n(Note that an abstract var requires a getter in addition to the setter)"
else analyzer.abstractVarMessage(member)
)
}
else if (underlying.isMethod) {
// If there is a concrete method whose name matches the unimplemented
// abstract method, and a cursory examination of the difference reveals
// something obvious to us, let's make it more obvious to them.
val abstractParams = underlying.tpe.paramTypes
val matchingName = clazz.tpe.nonPrivateMembersAdmitting(VBRIDGE)
val matchingArity = matchingName filter { m =>
!m.isDeferred &&
(m.name == underlying.name) &&
(m.tpe.paramTypes.size == underlying.tpe.paramTypes.size) &&
(m.tpe.typeParams.size == underlying.tpe.typeParams.size)
}
matchingArity match {
// So far so good: only one candidate method
case Scope(concrete) =>
val mismatches = abstractParams zip concrete.tpe.paramTypes filterNot { case (x, y) => x =:= y }
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 is a subclass of %s, but method parameter types must match exactly.".format(
c1.fullLocationString, c2.fullLocationString)
)
val addendum = (
if (abstractSym == concreteSym) {
// TODO: what is the optimal way to test for a raw type at this point?
// Compilation has already failed so we shouldn't have to worry overmuch
// about forcing types.
if (underlying.isJavaDefined && pa.typeArgs.isEmpty && abstractSym.typeParams.nonEmpty)
". To implement a raw type, use %s[_]".format(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 ""
)
undefined("\n(Note that %s does not match %s%s)".format(pa, pc, addendum))
case xs =>
undefined("")
}
case _ =>
undefined("")
}
}
else undefined("")
}
// Check the remainder for invalid absoverride.
for (member <- rest ; if (member.isAbstractOverride && member.isIncompleteIn(clazz))) {
val other = member.superSymbol(clazz)
val explanation =
if (other != NoSymbol) " and overrides incomplete superclass member " + infoString(other)
else ", but no concrete implementation could be found in a base class"
abstractClassError(true, infoString(member) + " is marked `abstract' and `override'" + explanation)
}
}
// 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) {
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(false, "there is a deferred declaration of "+infoString(decl)+
" which is not implemented in a subclass"+analyzer.abstractVarMessage(decl))
}
}
}
if (bc.superClass hasFlag ABSTRACT)
checkNoAbstractDecls(bc.superClass)
}
checkNoAbstractMembers()
if (abstractErrors.isEmpty)
checkNoAbstractDecls(clazz)
if (abstractErrors.nonEmpty)
unit.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.iterator) {
val overridden = decl.overriddenSymbol(ObjectClass)
if (overridden.isFinal)
unit.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) = unit.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
}
}
// 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) {
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) {
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 =>
println("??? base "+baseClass+" not found in basetypes of "+clazz)
case _ :: Nil =>
;// OK
case tp1 :: tp2 :: _ =>
unit.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 --------------------------------------------------------
private val ContraVariance = -1
private val NoVariance = 0
private val CoVariance = 1
private val AnyVariance = 2
private val escapedPrivateLocals = new mutable.HashSet[Symbol]
val varianceValidator = new Traverser {
/** Validate variance of info of symbol `base` */
private def validateVariance(base: Symbol) {
// A flag for when we're in a refinement, meaning method parameter types
// need to be checked.
var inRefinement = false
def varianceString(variance: Int): String =
if (variance == 1) "covariant"
else if (variance == -1) "contravariant"
else "invariant";
/** The variance of a symbol occurrence of `tvar`
* seen at the level of the definition of `base`.
* The search proceeds from `base` to the owner of `tvar`.
* Initially the state is covariant, but it might change along the search.
*/
def relativeVariance(tvar: Symbol): Int = {
val clazz = tvar.owner
var sym = base
var state = CoVariance
while (sym != clazz && state != AnyVariance) {
//Console.println("flip: " + sym + " " + sym.isParameter());//DEBUG
// Flip occurrences of type parameters and parameters, unless
// - it's a constructor, or case class factory or extractor
// - it's a type parameter of tvar's owner.
if (sym.isParameter && !sym.owner.isConstructor && !sym.owner.isCaseApplyOrUnapply &&
!(tvar.isTypeParameterOrSkolem && sym.isTypeParameterOrSkolem &&
tvar.owner == sym.owner)) state = -state;
else if (!sym.owner.isClass ||
sym.isTerm && ((sym.isPrivateLocal || sym.isProtectedLocal || sym.isSuperAccessor /* super accessors are implicitly local #4345*/) && !(escapedPrivateLocals contains sym))) {
// return AnyVariance if `sym` is local to a term
// or is private[this] or protected[this]
state = AnyVariance
} else if (sym.isAliasType) {
// return AnyVariance if `sym` is an alias type
// that does not override anything. This is OK, because we always
// expand aliases for variance checking.
// However, if `sym` does override a type in a base class
// we have to assume NoVariance, as there might then be
// references to the type parameter that are not variance checked.
state = if (sym.isOverridingSymbol) NoVariance else AnyVariance
}
sym = sym.owner
}
state
}
/** Validate that the type `tp` is variance-correct, assuming
* the type occurs itself at variance position given by `variance`
*/
def validateVariance(tp: Type, variance: Int): Unit = tp match {
case ErrorType =>
case WildcardType =>
case BoundedWildcardType(bounds) =>
validateVariance(bounds, variance)
case NoType =>
case NoPrefix =>
case ThisType(_) =>
case ConstantType(_) =>
// case DeBruijnIndex(_, _) =>
case SingleType(pre, sym) =>
validateVariance(pre, variance)
case TypeRef(pre, sym, args) =>
// println("validate "+sym+" at "+relativeVariance(sym))
if (sym.isAliasType/* && relativeVariance(sym) == AnyVariance*/)
validateVariance(tp.normalize, variance)
else if (sym.variance != NoVariance) {
val v = relativeVariance(sym)
if (v != AnyVariance && sym.variance != v * variance) {
//Console.println("relativeVariance(" + base + "," + sym + ") = " + v);//DEBUG
def tpString(tp: Type) = tp match {
case ClassInfoType(parents, _, clazz) => "supertype "+intersectionType(parents, clazz.owner)
case _ => "type "+tp
}
unit.error(base.pos,
varianceString(sym.variance) + " " + sym +
" occurs in " + varianceString(v * variance) +
" position in " + tpString(base.info) + " of " + base);
}
}
validateVariance(pre, variance)
// @M for higher-kinded typeref, args.isEmpty
// However, these args respect variances by construction anyway
// -- the interesting case is in type application, see checkKindBounds in Infer
if (args.nonEmpty)
validateVarianceArgs(args, variance, sym.typeParams)
case ClassInfoType(parents, decls, symbol) =>
validateVariances(parents, variance)
case RefinedType(parents, decls) =>
validateVariances(parents, variance)
val saved = inRefinement
inRefinement = true
for (sym <- decls)
validateVariance(sym.info, if (sym.isAliasType) NoVariance else variance)
inRefinement = saved
case TypeBounds(lo, hi) =>
validateVariance(lo, -variance)
validateVariance(hi, variance)
case mt @ MethodType(formals, result) =>
if (inRefinement)
validateVariances(mt.paramTypes, -variance)
validateVariance(result, variance)
case NullaryMethodType(result) =>
validateVariance(result, variance)
case PolyType(tparams, result) =>
// type parameters will be validated separately, because they are defined explicitly.
validateVariance(result, variance)
case ExistentialType(tparams, result) =>
validateVariances(tparams map (_.info), variance)
validateVariance(result, variance)
case AnnotatedType(annots, tp, selfsym) =>
if (!annots.exists(_ matches uncheckedVarianceClass))
validateVariance(tp, variance)
}
def validateVariances(tps: List[Type], variance: Int) {
tps foreach (tp => validateVariance(tp, variance))
}
def validateVarianceArgs(tps: List[Type], variance: Int, tparams: List[Symbol]) {
foreach2(tps, tparams)((tp, tparam) => validateVariance(tp, variance * tparam.variance))
}
validateVariance(base.info, CoVariance)
}
override def traverse(tree: Tree) {
tree match {
case ClassDef(_, _, _, _) | TypeDef(_, _, _, _) =>
validateVariance(tree.symbol)
super.traverse(tree)
// ModuleDefs need not be considered because they have been eliminated already
case ValDef(_, _, _, _) =>
if (!tree.symbol.hasLocalFlag)
validateVariance(tree.symbol)
case DefDef(_, _, tparams, vparamss, _, _) =>
// No variance check for object-private/protected methods/values.
if (!tree.symbol.hasLocalFlag) {
validateVariance(tree.symbol)
traverseTrees(tparams)
traverseTreess(vparamss)
}
case Template(_, _, _) =>
super.traverse(tree)
case _ =>
}
}
}
// Forward reference checking ---------------------------------------------------