Scala example source code file (Erasure.scala)
The Erasure.scala Scala example source code/* NSC -- new Scala compiler
* Copyright 2005-2013 LAMP/EPFL
* @author Martin Odersky
*/
package scala.tools.nsc
package transform
import scala.reflect.internal.ClassfileConstants._
import scala.collection.{ mutable, immutable }
import symtab._
import Flags._
import scala.reflect.internal.Mode._
abstract class Erasure extends AddInterfaces
with scala.reflect.internal.transform.Erasure
with typechecker.Analyzer
with TypingTransformers
with ast.TreeDSL
with TypeAdaptingTransformer
{
import global._
import definitions._
import CODE._
val analyzer: typechecker.Analyzer { val global: Erasure.this.global.type } =
this.asInstanceOf[typechecker.Analyzer { val global: Erasure.this.global.type }]
val phaseName: String = "erasure"
def newTransformer(unit: CompilationUnit): Transformer =
new ErasureTransformer(unit)
override def keepsTypeParams = false
// -------- erasure on types --------------------------------------------------------
// convert a numeric with a toXXX method
def numericConversion(tree: Tree, numericSym: Symbol): Tree = {
val mname = newTermName("to" + numericSym.name)
val conversion = tree.tpe member mname
assert(conversion != NoSymbol, tree + " => " + numericSym)
atPos(tree.pos)(Apply(Select(tree, conversion), Nil))
}
private object NeedsSigCollector extends TypeCollector(false) {
def traverse(tp: Type) {
if (!result) {
tp match {
case st: SubType =>
traverse(st.supertype)
case TypeRef(pre, sym, args) =>
if (sym == ArrayClass) args foreach traverse
else if (sym.isTypeParameterOrSkolem || sym.isExistentiallyBound || !args.isEmpty) result = true
else if (sym.isClass) traverse(rebindInnerClass(pre, sym)) // #2585
else if (!sym.isTopLevel) traverse(pre)
case PolyType(_, _) | ExistentialType(_, _) =>
result = true
case RefinedType(parents, _) =>
parents foreach traverse
case ClassInfoType(parents, _, _) =>
parents foreach traverse
case AnnotatedType(_, atp) =>
traverse(atp)
case _ =>
mapOver(tp)
}
}
}
}
override protected def verifyJavaErasure = settings.Xverify || settings.debug
def needsJavaSig(tp: Type) = !settings.Ynogenericsig && NeedsSigCollector.collect(tp)
// only refer to type params that will actually make it into the sig, this excludes:
// * higher-order type parameters
// * type parameters appearing in method parameters
// * type members not visible in an enclosing template
private def isTypeParameterInSig(sym: Symbol, initialSymbol: Symbol) = (
!sym.isHigherOrderTypeParameter &&
sym.isTypeParameterOrSkolem && (
(initialSymbol.enclClassChain.exists(sym isNestedIn _)) ||
(initialSymbol.isMethod && initialSymbol.typeParams.contains(sym))
)
)
// Ensure every '.' in the generated signature immediately follows
// a close angle bracket '>'. Any which do not are replaced with '$'.
// This arises due to multiply nested classes in the face of the
// rewriting explained at rebindInnerClass. This should be done in a
// more rigorous way up front rather than catching it after the fact,
// but that will be more involved.
private def dotCleanup(sig: String): String = {
// OPT 50% of time in generic signatures (~1% of compile time) was in this method, hence the imperative rewrite.
var last: Char = '\u0000'
var i = 0
val len = sig.length
val copy: Array[Char] = sig.toCharArray
var changed = false
while (i < sig.length) {
val ch = copy(i)
if (ch == '.' && last != '>') {
copy(i) = '$'
changed = true
}
last = ch
i += 1
}
if (changed) new String(copy) else sig
}
/** This object is only used for sanity testing when -check:genjvm is set.
* In that case we make sure that the erasure of the `normalized` type
* is the same as the erased type that's generated. Normalization means
* unboxing some primitive types and further simplifications as they are done in jsig.
*/
val prepareSigMap = new TypeMap {
def squashBoxed(tp: Type): Type = tp.dealiasWiden match {
case t @ RefinedType(parents, decls) =>
val parents1 = parents mapConserve squashBoxed
if (parents1 eq parents) tp
else RefinedType(parents1, decls)
case t @ ExistentialType(tparams, tpe) =>
val tpe1 = squashBoxed(tpe)
if (tpe1 eq tpe) t
else ExistentialType(tparams, tpe1)
case t =>
if (boxedClass contains t.typeSymbol) ObjectTpe
else tp
}
def apply(tp: Type): Type = tp.dealiasWiden match {
case tp1 @ TypeBounds(lo, hi) =>
val lo1 = squashBoxed(apply(lo))
val hi1 = squashBoxed(apply(hi))
if ((lo1 eq lo) && (hi1 eq hi)) tp1
else TypeBounds(lo1, hi1)
case tp1 @ TypeRef(pre, sym, args) =>
def argApply(tp: Type) = {
val tp1 = apply(tp)
if (tp1.typeSymbol == UnitClass) ObjectTpe
else squashBoxed(tp1)
}
if (sym == ArrayClass && args.nonEmpty)
if (unboundedGenericArrayLevel(tp1) == 1) ObjectTpe
else mapOver(tp1)
else if (sym == AnyClass || sym == AnyValClass || sym == SingletonClass)
ObjectTpe
else if (sym == UnitClass)
BoxedUnitTpe
else if (sym == NothingClass)
RuntimeNothingClass.tpe
else if (sym == NullClass)
RuntimeNullClass.tpe
else {
val pre1 = apply(pre)
val args1 = args mapConserve argApply
if ((pre1 eq pre) && (args1 eq args)) tp1
else TypeRef(pre1, sym, args1)
}
case tp1 @ MethodType(params, restpe) =>
val params1 = mapOver(params)
val restpe1 = if (restpe.typeSymbol == UnitClass) UnitTpe else apply(restpe)
if ((params1 eq params) && (restpe1 eq restpe)) tp1
else MethodType(params1, restpe1)
case tp1 @ RefinedType(parents, decls) =>
val parents1 = parents mapConserve apply
if (parents1 eq parents) tp1
else RefinedType(parents1, decls)
case t @ ExistentialType(tparams, tpe) =>
val tpe1 = apply(tpe)
if (tpe1 eq tpe) t
else ExistentialType(tparams, tpe1)
case tp1: ClassInfoType =>
tp1
case tp1 =>
mapOver(tp1)
}
}
private def hiBounds(bounds: TypeBounds): List[Type] = bounds.hi.dealiasWiden match {
case RefinedType(parents, _) => parents map (_.dealiasWiden)
case tp => tp :: Nil
}
private def isErasedValueType(tpe: Type) = tpe.isInstanceOf[ErasedValueType]
/** The Java signature of type 'info', for symbol sym. The symbol is used to give the right return
* type for constructors.
*/
def javaSig(sym0: Symbol, info: Type): Option[String] = enteringErasure {
val isTraitSignature = sym0.enclClass.isTrait
def superSig(parents: List[Type]) = {
val ps = (
if (isTraitSignature) {
// java is unthrilled about seeing interfaces inherit from classes
val ok = parents filter (p => p.typeSymbol.isTrait || p.typeSymbol.isInterface)
// traits should always list Object.
if (ok.isEmpty || ok.head.typeSymbol != ObjectClass) ObjectTpe :: ok
else ok
}
else parents
)
(ps map boxedSig).mkString
}
def boxedSig(tp: Type) = jsig(tp, primitiveOK = false)
def boundsSig(bounds: List[Type]) = {
val (isTrait, isClass) = bounds partition (_.typeSymbol.isTrait)
val classPart = isClass match {
case Nil => ":" // + boxedSig(ObjectTpe)
case x :: _ => ":" + boxedSig(x)
}
classPart :: (isTrait map boxedSig) mkString ":"
}
def paramSig(tsym: Symbol) = tsym.name + boundsSig(hiBounds(tsym.info.bounds))
def polyParamSig(tparams: List[Symbol]) = (
if (tparams.isEmpty) ""
else tparams map paramSig mkString ("<", "", ">")
)
// Anything which could conceivably be a module (i.e. isn't known to be
// a type parameter or similar) must go through here or the signature is
// likely to end up with Foo<T>.Empty where it needs Foo<T>.Empty$.
def fullNameInSig(sym: Symbol) = "L" + enteringIcode(sym.javaBinaryName)
def jsig(tp0: Type, existentiallyBound: List[Symbol] = Nil, toplevel: Boolean = false, primitiveOK: Boolean = true): String = {
val tp = tp0.dealias
tp match {
case st: SubType =>
jsig(st.supertype, existentiallyBound, toplevel, primitiveOK)
case ExistentialType(tparams, tpe) =>
jsig(tpe, tparams, toplevel, primitiveOK)
case TypeRef(pre, sym, args) =>
def argSig(tp: Type) =
if (existentiallyBound contains tp.typeSymbol) {
val bounds = tp.typeSymbol.info.bounds
if (!(AnyRefTpe <:< bounds.hi)) "+" + boxedSig(bounds.hi)
else if (!(bounds.lo <:< NullTpe)) "-" + boxedSig(bounds.lo)
else "*"
} else tp match {
case PolyType(_, res) =>
"*" // SI-7932
case _ =>
boxedSig(tp)
}
def classSig = {
val preRebound = pre.baseType(sym.owner) // #2585
dotCleanup(
(
if (needsJavaSig(preRebound)) {
val s = jsig(preRebound, existentiallyBound)
if (s.charAt(0) == 'L') s.substring(0, s.length - 1) + "." + sym.javaSimpleName
else fullNameInSig(sym)
}
else fullNameInSig(sym)
) + (
if (args.isEmpty) "" else
"<"+(args map argSig).mkString+">"
) + (
";"
)
)
}
// If args isEmpty, Array is being used as a type constructor
if (sym == ArrayClass && args.nonEmpty) {
if (unboundedGenericArrayLevel(tp) == 1) jsig(ObjectTpe)
else ARRAY_TAG.toString+(args map (jsig(_))).mkString
}
else if (isTypeParameterInSig(sym, sym0)) {
assert(!sym.isAliasType, "Unexpected alias type: " + sym)
"" + TVAR_TAG + sym.name + ";"
}
else if (sym == AnyClass || sym == AnyValClass || sym == SingletonClass)
jsig(ObjectTpe)
else if (sym == UnitClass)
jsig(BoxedUnitTpe)
else if (sym == NothingClass)
jsig(RuntimeNothingClass.tpe)
else if (sym == NullClass)
jsig(RuntimeNullClass.tpe)
else if (isPrimitiveValueClass(sym)) {
if (!primitiveOK) jsig(ObjectTpe)
else if (sym == UnitClass) jsig(BoxedUnitTpe)
else abbrvTag(sym).toString
}
else if (sym.isDerivedValueClass) {
val unboxed = sym.derivedValueClassUnbox.tpe_*.finalResultType
val unboxedSeen = (tp memberType sym.derivedValueClassUnbox).finalResultType
def unboxedMsg = if (unboxed == unboxedSeen) "" else s", seen within ${sym.simpleName} as $unboxedSeen"
logResult(s"Erasure of value class $sym (underlying type $unboxed$unboxedMsg) is") {
if (isPrimitiveValueType(unboxedSeen) && !primitiveOK)
classSig
else
jsig(unboxedSeen, existentiallyBound, toplevel, primitiveOK)
}
}
else if (sym.isClass)
classSig
else
jsig(erasure(sym0)(tp), existentiallyBound, toplevel, primitiveOK)
case PolyType(tparams, restpe) =>
assert(tparams.nonEmpty)
val poly = if (toplevel) polyParamSig(tparams) else ""
poly + jsig(restpe)
case MethodType(params, restpe) =>
val buf = new StringBuffer("(")
params foreach (p => buf append jsig(p.tpe))
buf append ")"
buf append (if (restpe.typeSymbol == UnitClass || sym0.isConstructor) VOID_TAG.toString else jsig(restpe))
buf.toString
case RefinedType(parent :: _, decls) =>
boxedSig(parent)
case ClassInfoType(parents, _, _) =>
superSig(parents)
case AnnotatedType(_, atp) =>
jsig(atp, existentiallyBound, toplevel, primitiveOK)
case BoundedWildcardType(bounds) =>
println("something's wrong: "+sym0+":"+sym0.tpe+" has a bounded wildcard type")
jsig(bounds.hi, existentiallyBound, toplevel, primitiveOK)
case _ =>
val etp = erasure(sym0)(tp)
if (etp eq tp) throw new UnknownSig
else jsig(etp)
}
}
if (needsJavaSig(info)) {
try Some(jsig(info, toplevel = true))
catch { case ex: UnknownSig => None }
}
else None
}
class UnknownSig extends Exception
/** The symbol's erased info. This is the type's erasure, except for the following symbols:
*
* - For $asInstanceOf : [T]T
* - For $isInstanceOf : [T]scala#Boolean
* - For class Array : [T]C where C is the erased classinfo of the Array class.
* - For Array[T].<init> : {scala#Int)Array[T]
* - For a type parameter : A type bounds type consisting of the erasures of its bounds.
*/
override def transformInfo(sym: Symbol, tp: Type): Type =
transformMixinInfo(super.transformInfo(sym, tp))
val deconstMap = new TypeMap {
// For some reason classOf[Foo] creates ConstantType(Constant(tpe)) with an actual Type for tpe,
// which is later translated to a Class. Unfortunately that means we have bugs like the erasure
// of Class[Foo] and classOf[Bar] not being seen as equivalent, leading to duplicate method
// generation and failing bytecode. See ticket #4753.
def apply(tp: Type): Type = tp match {
case PolyType(_, _) => mapOver(tp)
case MethodType(_, _) => mapOver(tp) // nullarymethod was eliminated during uncurry
case ConstantType(Constant(_: Type)) => ClassClass.tpe // all classOfs erase to Class
case _ => tp.deconst
}
}
// ## requires a little translation
private lazy val poundPoundMethods = Set[Symbol](Any_##, Object_##)
// Methods on Any/Object which we rewrite here while we still know what
// is a primitive and what arrived boxed.
private lazy val interceptedMethods = poundPoundMethods ++ primitiveGetClassMethods
// -------- erasure on trees ------------------------------------------
override def newTyper(context: Context) = new Eraser(context)
class ComputeBridges(unit: CompilationUnit, root: Symbol) {
assert(phase == currentRun.erasurePhase, phase)
var toBeRemoved = immutable.Set[Symbol]()
val site = root.thisType
val bridgesScope = newScope
val bridgeTarget = mutable.HashMap[Symbol, Symbol]()
var bridges = List[Tree]()
val opc = enteringExplicitOuter {
new overridingPairs.Cursor(root) {
override def parents = List(root.info.firstParent)
override def exclude(sym: Symbol) = !sym.isMethod || super.exclude(sym)
}
}
def compute(): (List[Tree], immutable.Set[Symbol]) = {
while (opc.hasNext) {
if (enteringExplicitOuter(!opc.low.isDeferred))
checkPair(opc.currentPair)
opc.next()
}
(bridges, toBeRemoved)
}
/** Check that a bridge only overrides members that are also overridden by the original member.
* This test is necessary only for members that have a value class in their type.
* Such members are special because their types after erasure and after post-erasure differ/.
* This means we generate them after erasure, but the post-erasure transform might introduce
* a name clash. The present method guards against these name clashes.
*
* @param member The original member
* @param other The overidden symbol for which the bridge was generated
* @param bridge The bridge
*/
def checkBridgeOverrides(member: Symbol, other: Symbol, bridge: Symbol): Seq[(Position, String)] = {
def fulldef(sym: Symbol) =
if (sym == NoSymbol) sym.toString
else s"$sym: ${sym.tpe} in ${sym.owner}"
var noclash = true
val clashErrors = mutable.Buffer[(Position, String)]()
def clashError(what: String) = {
val pos = if (member.owner == root) member.pos else root.pos
val msg = sm"""bridge generated for member ${fulldef(member)}
|which overrides ${fulldef(other)}
|clashes with definition of $what;
|both have erased type ${exitingPostErasure(bridge.tpe)}"""
clashErrors += Tuple2(pos, msg)
}
for (bc <- root.baseClasses) {
if (settings.debug)
exitingPostErasure(println(
sm"""check bridge overrides in $bc
|${bc.info.nonPrivateDecl(bridge.name)}
|${site.memberType(bridge)}
|${site.memberType(bc.info.nonPrivateDecl(bridge.name) orElse IntClass)}
|${(bridge.matchingSymbol(bc, site))}"""))
def overriddenBy(sym: Symbol) =
sym.matchingSymbol(bc, site).alternatives filter (sym => !sym.isBridge)
for (overBridge <- exitingPostErasure(overriddenBy(bridge))) {
if (overBridge == member) {
clashError("the member itself")
} else {
val overMembers = overriddenBy(member)
if (!overMembers.exists(overMember =>
exitingPostErasure(overMember.tpe =:= overBridge.tpe))) {
clashError(fulldef(overBridge))
}
}
}
}
clashErrors
}
/** TODO - work through this logic with a fine-toothed comb, incorporating
* into SymbolPairs where appropriate.
*/
def checkPair(pair: SymbolPair) {
import pair._
val member = low
val other = high
val otpe = highErased
val bridgeNeeded = exitingErasure (
!member.isMacro &&
!(other.tpe =:= member.tpe) &&
!(deconstMap(other.tpe) =:= deconstMap(member.tpe)) &&
{ var e = bridgesScope.lookupEntry(member.name)
while ((e ne null) && !((e.sym.tpe =:= otpe) && (bridgeTarget(e.sym) == member)))
e = bridgesScope.lookupNextEntry(e)
(e eq null)
}
)
if (!bridgeNeeded)
return
val newFlags = (member.flags | BRIDGE | ARTIFACT) & ~(ACCESSOR | DEFERRED | LAZY | lateDEFERRED)
val bridge = other.cloneSymbolImpl(root, newFlags) setPos root.pos
debuglog("generating bridge from %s (%s): %s to %s: %s".format(
other, flagsToString(newFlags),
otpe + other.locationString, member,
specialErasure(root)(member.tpe) + member.locationString)
)
// the parameter symbols need to have the new owner
bridge setInfo (otpe cloneInfo bridge)
bridgeTarget(bridge) = member
def sigContainsValueClass = (member.tpe exists (_.typeSymbol.isDerivedValueClass))
val shouldAdd = (
!sigContainsValueClass
|| (checkBridgeOverrides(member, other, bridge) match {
case Nil => true
case es if member.owner.isAnonymousClass => resolveAnonymousBridgeClash(member, bridge); true
case es => for ((pos, msg) <- es) unit.error(pos, msg); false
})
)
if (shouldAdd) {
exitingErasure(root.info.decls enter bridge)
if (other.owner == root) {
exitingErasure(root.info.decls.unlink(other))
toBeRemoved += other
}
bridgesScope enter bridge
bridges ::= makeBridgeDefDef(bridge, member, other)
}
}
def makeBridgeDefDef(bridge: Symbol, member: Symbol, other: Symbol) = exitingErasure {
// type checking ensures we can safely call `other`, but unless `member.tpe <:< other.tpe`,
// calling `member` is not guaranteed to succeed in general, there's
// nothing we can do about this, except for an unapply: when this subtype test fails,
// return None without calling `member`
//
// TODO: should we do this for user-defined unapplies as well?
// does the first argument list have exactly one argument -- for user-defined unapplies we can't be sure
def maybeWrap(bridgingCall: Tree): Tree = {
val guardExtractor = ( // can't statically know which member is going to be selected, so don't let this depend on member.isSynthetic
(member.name == nme.unapply || member.name == nme.unapplySeq)
&& !exitingErasure((member.tpe <:< other.tpe))) // no static guarantees (TODO: is the subtype test ever true?)
import CODE._
val _false = FALSE
val pt = member.tpe.resultType
lazy val zero =
if (_false.tpe <:< pt) _false
else if (NoneModule.tpe <:< pt) REF(NoneModule)
else EmptyTree
if (guardExtractor && (zero ne EmptyTree)) {
val typeTest = gen.mkIsInstanceOf(REF(bridge.firstParam), member.tpe.params.head.tpe)
IF (typeTest) THEN bridgingCall ELSE zero
} else bridgingCall
}
val rhs = member.tpe match {
case MethodType(Nil, ConstantType(c)) => Literal(c)
case _ =>
val sel: Tree = Select(This(root), member)
val bridgingCall = (sel /: bridge.paramss)((fun, vparams) => Apply(fun, vparams map Ident))
maybeWrap(bridgingCall)
}
DefDef(bridge, rhs)
}
}
/** The modifier typer which retypes with erased types. */
class Eraser(_context: Context) extends Typer(_context) with TypeAdapter {
val typer = this.asInstanceOf[analyzer.Typer]
override protected def stabilize(tree: Tree, pre: Type, mode: Mode, pt: Type): Tree = tree
/** Replace member references as follows:
*
* - `x == y` for == in class Any becomes `x equals y` with equals in class Object.
* - `x != y` for != in class Any becomes `!(x equals y)` with equals in class Object.
* - x.asInstanceOf[T] becomes x.$asInstanceOf[T]
* - x.isInstanceOf[T] becomes x.$isInstanceOf[T]
* - x.isInstanceOf[ErasedValueType(tref)] becomes x.isInstanceOf[tref.sym.tpe]
* - x.m where m is some other member of Any becomes x.m where m is a member of class Object.
* - x.m where x has unboxed value type T and m is not a directly translated member of T becomes T.box(x).m
* - x.m where x is a reference type and m is a directly translated member of value type T becomes x.TValue().m
* - All forms of x.m where x is a boxed type and m is a member of an unboxed class become
* x.m where m is the corresponding member of the boxed class.
*/
private def adaptMember(tree: Tree): Tree = {
//Console.println("adaptMember: " + tree);
tree match {
case Apply(ta @ TypeApply(sel @ Select(qual, name), List(targ)), List())
if tree.symbol == Any_asInstanceOf =>
val qual1 = typedQualifier(qual, NOmode, ObjectTpe) // need to have an expected type, see #3037
// !!! Make pending/run/t5866b.scala work. The fix might be here and/or in unbox1.
if (isPrimitiveValueType(targ.tpe) || isErasedValueType(targ.tpe)) {
val noNullCheckNeeded = targ.tpe match {
case ErasedValueType(_, underlying) =>
isPrimitiveValueClass(underlying.typeSymbol)
case _ =>
true
}
if (noNullCheckNeeded) unbox(qual1, targ.tpe)
else {
val untyped =
// util.trace("new asinstanceof test") {
gen.evalOnce(qual1, context.owner, context.unit) { qual =>
If(Apply(Select(qual(), nme.eq), List(Literal(Constant(null)) setType NullTpe)),
Literal(Constant(null)) setType targ.tpe,
unbox(qual(), targ.tpe))
}
// }
typed(untyped)
}
} else treeCopy.Apply(tree, treeCopy.TypeApply(ta, treeCopy.Select(sel, qual1, name), List(targ)), List())
case Apply(TypeApply(sel @ Select(qual, name), List(targ)), List())
if tree.symbol == Any_isInstanceOf =>
targ.tpe match {
case ErasedValueType(clazz, _) => targ.setType(clazz.tpe)
case _ =>
}
tree
case Select(qual, name) =>
if (tree.symbol == NoSymbol) {
tree
} else if (name == nme.CONSTRUCTOR) {
if (tree.symbol.owner == AnyValClass) tree.symbol = ObjectClass.primaryConstructor
tree
} else if (tree.symbol == Any_asInstanceOf)
adaptMember(atPos(tree.pos)(Select(qual, Object_asInstanceOf)))
else if (tree.symbol == Any_isInstanceOf)
adaptMember(atPos(tree.pos)(Select(qual, Object_isInstanceOf)))
else if (tree.symbol.owner == AnyClass)
adaptMember(atPos(tree.pos)(Select(qual, getMember(ObjectClass, tree.symbol.name))))
else {
var qual1 = typedQualifier(qual)
if ((isPrimitiveValueType(qual1.tpe) && !isPrimitiveValueMember(tree.symbol)) ||
isErasedValueType(qual1.tpe))
qual1 = box(qual1, "owner "+tree.symbol.owner)
else if (!isPrimitiveValueType(qual1.tpe) && isPrimitiveValueMember(tree.symbol))
qual1 = unbox(qual1, tree.symbol.owner.tpe)
def selectFrom(qual: Tree) = treeCopy.Select(tree, qual, name)
if (isPrimitiveValueMember(tree.symbol) && !isPrimitiveValueType(qual1.tpe)) {
tree.symbol = NoSymbol
selectFrom(qual1)
} else if (isMethodTypeWithEmptyParams(qual1.tpe)) {
assert(qual1.symbol.isStable, qual1.symbol)
val applied = Apply(qual1, List()) setPos qual1.pos setType qual1.tpe.resultType
adaptMember(selectFrom(applied))
} else if (!(qual1.isInstanceOf[Super] || (qual1.tpe.typeSymbol isSubClass tree.symbol.owner))) {
assert(tree.symbol.owner != ArrayClass)
selectFrom(cast(qual1, tree.symbol.owner.tpe))
} else {
selectFrom(qual1)
}
}
case SelectFromArray(qual, name, erasure) =>
var qual1 = typedQualifier(qual)
if (!(qual1.tpe <:< erasure)) qual1 = cast(qual1, erasure)
Select(qual1, name) copyAttrs tree
case _ =>
tree
}
}
/** A replacement for the standard typer's adapt method.
*/
override protected def adapt(tree: Tree, mode: Mode, pt: Type, original: Tree = EmptyTree): Tree =
adaptToType(tree, pt)
/** A replacement for the standard typer's `typed1` method.
*/
override def typed1(tree: Tree, mode: Mode, pt: Type): Tree = {
val tree1 = try {
tree match {
case InjectDerivedValue(arg) =>
(tree.attachments.get[TypeRefAttachment]: @unchecked) match {
case Some(itype) =>
val tref = itype.tpe
val argPt = enteringErasure(erasedValueClassArg(tref))
log(s"transforming inject $arg -> $tref/$argPt")
val result = typed(arg, mode, argPt)
log(s"transformed inject $arg -> $tref/$argPt = $result:${result.tpe}")
return result setType ErasedValueType(tref.sym, result.tpe)
}
case _ =>
super.typed1(adaptMember(tree), mode, pt)
}
} catch {
case er: TypeError =>
Console.println("exception when typing " + tree+"/"+tree.getClass)
Console.println(er.msg + " in file " + context.owner.sourceFile)
er.printStackTrace
abort("unrecoverable error")
case ex: Exception =>
//if (settings.debug.value)
try Console.println("exception when typing " + tree)
finally throw ex
throw ex
}
def adaptCase(cdef: CaseDef): CaseDef = {
val newCdef = deriveCaseDef(cdef)(adaptToType(_, tree1.tpe))
newCdef setType newCdef.body.tpe
}
def adaptBranch(branch: Tree): Tree =
if (branch == EmptyTree) branch else adaptToType(branch, tree1.tpe)
tree1 match {
case If(cond, thenp, elsep) =>
treeCopy.If(tree1, cond, adaptBranch(thenp), adaptBranch(elsep))
case Match(selector, cases) =>
treeCopy.Match(tree1, selector, cases map adaptCase)
case Try(block, catches, finalizer) =>
treeCopy.Try(tree1, adaptBranch(block), catches map adaptCase, finalizer)
case Ident(_) | Select(_, _) =>
if (tree1.symbol.isOverloaded) {
val first = tree1.symbol.alternatives.head
val sym1 = tree1.symbol.filter {
alt => alt == first || !(first.tpe looselyMatches alt.tpe)
}
if (tree.symbol ne sym1) {
tree1 setSymbol sym1 setType sym1.tpe
}
}
tree1
case _ =>
tree1
}
}
}
/** The erasure transformer */
class ErasureTransformer(unit: CompilationUnit) extends Transformer {
import overridingPairs.Cursor
private def doubleDefError(pair: SymbolPair) {
import pair._
if (!pair.isErroneous) {
val what = (
if (low.owner == high.owner) "double definition"
else if (low.owner == base) "name clash between defined and inherited member"
else "name clash between inherited members"
)
val when = if (exitingRefchecks(lowType matches highType)) "" else " after erasure: " + exitingPostErasure(highType)
unit.error(pos,
s"""|$what:
|${exitingRefchecks(highString)} and
|${exitingRefchecks(lowString)}
|have same type$when""".trim.stripMargin
)
}
low setInfo ErrorType
}
private def sameTypeAfterErasure(sym1: Symbol, sym2: Symbol) =
exitingPostErasure(sym1.info =:= sym2.info) && !sym1.isMacro && !sym2.isMacro
/** TODO - adapt SymbolPairs so it can be used here. */
private def checkNoDeclaredDoubleDefs(base: Symbol) {
val decls = base.info.decls
// SI-8010 force infos, otherwise makeNotPrivate in ExplicitOuter info transformer can trigger
// a scope rehash while were iterating and we can see the same entry twice!
// Inspection of SymbolPairs (the basis of OverridingPairs), suggests that it is immune
// from this sort of bug as it copies the symbols into a temporary scope *before* any calls to `.info`,
// ie, no variant of it calls `info` or `tpe` in `SymbolPair#exclude`.
//
// Why not just create a temporary scope here? We need to force the name changes in any case before
// we do these checks, so that we're comparing same-named methods based on the expanded names that actually
// end up in the bytecode.
exitingPostErasure(decls.foreach(_.info))
var e = decls.elems
while (e ne null) {
if (e.sym.isTerm) {
var e1 = decls lookupNextEntry e
while (e1 ne null) {
assert(e.sym ne e1.sym, s"Internal error: encountered ${e.sym.debugLocationString} twice during scope traversal. This might be related to SI-8010.")
if (sameTypeAfterErasure(e.sym, e1.sym))
doubleDefError(new SymbolPair(base, e.sym, e1.sym))
e1 = decls lookupNextEntry e1
}
}
e = e.next
}
}
/** Emit an error if there is a double definition. This can happen if:
*
* - A template defines two members with the same name and erased type.
* - A template defines and inherits two members `m` with different types,
* but their erased types are the same.
* - A template inherits two members `m` with different types,
* but their erased types are the same.
*/
private def checkNoDoubleDefs(root: Symbol) {
checkNoDeclaredDoubleDefs(root)
object opc extends Cursor(root) {
// specialized members have no type history before 'specialize', causing double def errors for curried defs
override def exclude(sym: Symbol): Boolean = (
sym.isType
|| sym.isPrivate
|| super.exclude(sym)
|| !sym.hasTypeAt(currentRun.refchecksPhase.id)
)
override def matches(lo: Symbol, high: Symbol) = true
}
def isErasureDoubleDef(pair: SymbolPair) = {
import pair._
log(s"Considering for erasure clash:\n$pair")
!exitingRefchecks(lowType matches highType) && sameTypeAfterErasure(low, high)
}
opc.iterator filter isErasureDoubleDef foreach doubleDefError
}
/** Add bridge definitions to a template. This means:
*
* If there is a concrete member `m` which overrides a member in a base
* class of the template, and the erased types of the two members differ,
* and the two members are not inherited or defined by some parent class
* of the template, then a bridge from the overridden member `m1` to the
* member `m0` is added. The bridge has the erased type of `m1` and
* forwards to `m0`.
*
* No bridge is added if there is already a bridge to `m0` with the erased
* type of `m1` in the template.
*/
private def bridgeDefs(owner: Symbol): (List[Tree], immutable.Set[Symbol]) = {
assert(phase == currentRun.erasurePhase, phase)
new ComputeBridges(unit, owner) compute()
}
def addBridges(stats: List[Tree], base: Symbol): List[Tree] =
if (base.isTrait) stats
else {
val (bridges, toBeRemoved) = bridgeDefs(base)
if (bridges.isEmpty) stats
else (stats filterNot (stat => toBeRemoved contains stat.symbol)) ::: bridges
}
/** Transform tree at phase erasure before retyping it.
* This entails the following:
*
* - Remove all type parameters in class and method definitions.
* - Remove all abstract and alias type definitions.
* - Remove all type applications other than those involving a type test or cast.
* - Remove all empty trees in statements and definitions in a PackageDef.
* - Check that there are no double definitions in a template.
* - Add bridge definitions to a template.
* - Replace all types in type nodes and the EmptyTree object by their erasure.
* Type nodes of type Unit representing result types of methods are left alone.
* - Given a selection q.s, where the owner of `s` is not accessible but the
* type symbol of q's type qT is accessible, insert a cast (q.asInstanceOf[qT]).s
* This prevents illegal access errors (see #4283).
* - Remove all instance creations new C(arg) where C is an inlined class.
* - Reset all other type attributes to null, thus enforcing a retyping.
*/
private val preTransformer = new TypingTransformer(unit) {
private def preEraseNormalApply(tree: Apply) = {
val fn = tree.fun
val args = tree.args
def qualifier = fn match {
case Select(qual, _) => qual
case TypeApply(Select(qual, _), _) => qual
}
def preEraseAsInstanceOf = {
(fn: @unchecked) match {
case TypeApply(Select(qual, _), List(targ)) =>
if (qual.tpe <:< targ.tpe)
atPos(tree.pos) { Typed(qual, TypeTree(targ.tpe)) }
else if (isNumericValueClass(qual.tpe.typeSymbol) && isNumericValueClass(targ.tpe.typeSymbol))
atPos(tree.pos)(numericConversion(qual, targ.tpe.typeSymbol))
else
tree
}
// todo: also handle the case where the singleton type is buried in a compound
}
def preEraseIsInstanceOf = {
fn match {
case TypeApply(sel @ Select(qual, name), List(targ)) =>
if (qual.tpe != null && isPrimitiveValueClass(qual.tpe.typeSymbol) && targ.tpe != null && targ.tpe <:< AnyRefTpe)
unit.error(sel.pos, "isInstanceOf cannot test if value types are references.")
def mkIsInstanceOf(q: () => Tree)(tp: Type): Tree =
Apply(
TypeApply(
Select(q(), Object_isInstanceOf) setPos sel.pos,
List(TypeTree(tp) setPos targ.pos)) setPos fn.pos,
List()) setPos tree.pos
targ.tpe match {
case SingleType(_, _) | ThisType(_) | SuperType(_, _) =>
val cmpOp = if (targ.tpe <:< AnyValTpe) Any_equals else Object_eq
atPos(tree.pos) {
Apply(Select(qual, cmpOp), List(gen.mkAttributedQualifier(targ.tpe)))
}
case RefinedType(parents, decls) if (parents.length >= 2) =>
gen.evalOnce(qual, currentOwner, unit) { q =>
// Optimization: don't generate isInstanceOf tests if the static type
// conforms, because it always succeeds. (Or at least it had better.)
// At this writing the pattern matcher generates some instance tests
// involving intersections where at least one parent is statically known true.
// That needs fixing, but filtering the parents here adds an additional
// level of robustness (in addition to the short term fix.)
val parentTests = parents filterNot (qual.tpe <:< _)
if (parentTests.isEmpty) Literal(Constant(true))
else atPos(tree.pos) {
parentTests map mkIsInstanceOf(q) reduceRight gen.mkAnd
}
}
case _ =>
tree
}
case _ => tree
}
}
if (fn.symbol == Any_asInstanceOf) {
preEraseAsInstanceOf
} else if (fn.symbol == Any_isInstanceOf) {
preEraseIsInstanceOf
} else if (fn.symbol.isOnlyRefinementMember) {
// !!! Another spot where we produce overloaded types (see test pos/t6301)
log(s"${fn.symbol.fullLocationString} originates in refinement class - call will be implemented via reflection.")
ApplyDynamic(qualifier, args) setSymbol fn.symbol setPos tree.pos
} else if (fn.symbol.isMethodWithExtension && !fn.symbol.tpe.isErroneous) {
Apply(gen.mkAttributedRef(extensionMethods.extensionMethod(fn.symbol)), qualifier :: args)
} else {
tree
}
}
private def preEraseApply(tree: Apply) = {
tree.fun match {
case TypeApply(fun @ Select(qual, name), args @ List(arg))
if ((fun.symbol == Any_isInstanceOf || fun.symbol == Object_isInstanceOf) &&
unboundedGenericArrayLevel(arg.tpe) > 0) => // !!! todo: simplify by having GenericArray also extract trees
val level = unboundedGenericArrayLevel(arg.tpe)
def isArrayTest(arg: Tree) =
gen.mkRuntimeCall(nme.isArray, List(arg, Literal(Constant(level))))
global.typer.typedPos(tree.pos) {
if (level == 1) isArrayTest(qual)
else gen.evalOnce(qual, currentOwner, unit) { qual1 =>
gen.mkAnd(
gen.mkMethodCall(
qual1(),
fun.symbol,
List(specialErasure(fun.symbol)(arg.tpe)),
Nil
),
isArrayTest(qual1())
)
}
}
case fn @ Select(qual, name) =>
val args = tree.args
if (fn.symbol.owner == ArrayClass) {
// Have to also catch calls to abstract types which are bounded by Array.
if (unboundedGenericArrayLevel(qual.tpe.widen) == 1 || qual.tpe.typeSymbol.isAbstractType) {
// convert calls to apply/update/length on generic arrays to
// calls of ScalaRunTime.array_xxx method calls
global.typer.typedPos(tree.pos) {
val arrayMethodName = name match {
case nme.apply => nme.array_apply
case nme.length => nme.array_length
case nme.update => nme.array_update
case nme.clone_ => nme.array_clone
case _ => unit.error(tree.pos, "Unexpected array member, no translation exists.") ; nme.NO_NAME
}
gen.mkRuntimeCall(arrayMethodName, qual :: args)
}
} else {
// store exact array erasure in map to be retrieved later when we might
// need to do the cast in adaptMember
// Note: No specialErasure needed here because we simply cast, on
// elimination of SelectFromArray, no boxing or unboxing is done there.
treeCopy.Apply(
tree,
SelectFromArray(qual, name, erasure(tree.symbol)(qual.tpe)).copyAttrs(fn),
args)
}
}
else if (args.isEmpty && interceptedMethods(fn.symbol)) {
if (poundPoundMethods.contains(fn.symbol)) {
// This is unattractive, but without it we crash here on ().## because after
// erasure the ScalaRunTime.hash overload goes from Unit => Int to BoxedUnit => Int.
// This must be because some earlier transformation is being skipped on ##, but so
// far I don't know what. For null we now define null.## == 0.
qual.tpe.typeSymbol match {
case UnitClass | NullClass => LIT(0)
case IntClass => qual
case s @ (ShortClass | ByteClass | CharClass) => numericConversion(qual, s)
case BooleanClass => If(qual, LIT(true.##), LIT(false.##))
case _ =>
// Since we are past typer, we need to avoid creating trees carrying
// overloaded types. This logic is custom (and technically incomplete,
// although serviceable) for def hash. What is really needed is for
// the overloading logic presently hidden away in a few different
// places to be properly exposed so we can just call "resolveOverload"
// after typer. Until then:
val alts = ScalaRunTimeModule.info.member(nme.hash_).alternatives
def alt1 = alts find (_.info.paramTypes.head =:= qual.tpe)
def alt2 = ScalaRunTimeModule.info.member(nme.hash_) suchThat (_.info.paramTypes.head.typeSymbol == AnyClass)
val newTree = gen.mkRuntimeCall(nme.hash_, qual :: Nil) setSymbol (alt1 getOrElse alt2)
global.typer.typed(newTree)
}
} else if (isPrimitiveValueClass(qual.tpe.typeSymbol)) {
// Rewrite 5.getClass to ScalaRunTime.anyValClass(5)
global.typer.typed(gen.mkRuntimeCall(nme.anyValClass, List(qual, typer.resolveClassTag(tree.pos, qual.tpe.widen))))
} else if (primitiveGetClassMethods.contains(fn.symbol)) {
// if we got here then we're trying to send a primitive getClass method to either
// a) an Any, in which cage Object_getClass works because Any erases to object. Or
//
// b) a non-primitive, e.g. because the qualifier's type is a refinement type where one parent
// of the refinement is a primitive and another is AnyRef. In that case
// we get a primitive form of _getClass trying to target a boxed value
// so we need replace that method name with Object_getClass to get correct behavior.
// See SI-5568.
tree setSymbol Object_getClass
} else {
debugwarn(s"The symbol '${fn.symbol}' was interecepted but didn't match any cases, that means the intercepted methods set doesn't match the code")
tree
}
} else qual match {
case New(tpt) if name == nme.CONSTRUCTOR && tpt.tpe.typeSymbol.isDerivedValueClass =>
// println("inject derived: "+arg+" "+tpt.tpe)
val List(arg) = args
val attachment = new TypeRefAttachment(tree.tpe.asInstanceOf[TypeRef])
InjectDerivedValue(arg) updateAttachment attachment
case _ =>
preEraseNormalApply(tree)
}
case _ =>
preEraseNormalApply(tree)
}
}
def preErase(tree: Tree): Tree = tree match {
case tree: Apply =>
preEraseApply(tree)
case TypeApply(fun, args) if (fun.symbol.owner != AnyClass &&
fun.symbol != Object_asInstanceOf &&
fun.symbol != Object_isInstanceOf) =>
// leave all other type tests/type casts, remove all other type applications
preErase(fun)
case Select(qual, name) =>
val sym = tree.symbol
val owner = sym.owner
if (owner.isRefinementClass) {
sym.allOverriddenSymbols filterNot (_.owner.isRefinementClass) match {
case overridden :: _ =>
log(s"${sym.fullLocationString} originates in refinement class - replacing with ${overridden.fullLocationString}.")
tree.symbol = overridden
case Nil =>
// Ideally this should not be reached or reachable; anything which would
// get here should have been caught in the surrounding Apply.
devWarning(s"Failed to rewrite reflective apply - now don't know what to do with " + tree)
return treeCopy.Select(tree, gen.mkAttributedCast(qual, qual.tpe.widen), name)
}
}
def isAccessible(sym: Symbol) = localTyper.context.isAccessible(sym, sym.owner.thisType)
if (!isAccessible(owner) && qual.tpe != null) {
qual match {
case Super(_, _) =>
// Insert a cast here at your peril -- see SI-5162. Bail out if the target method is defined in
// Java, otherwise, we'd get an IllegalAccessError at runtime. If the target method is defined in
// Scala, however, we should have access.
if (owner.isJavaDefined) unit.error(tree.pos, s"Unable to access ${tree.symbol.fullLocationString} with a super reference.")
tree
case _ =>
// Todo: Figure out how qual.tpe could be null in the check above (it does appear in build where SwingWorker.this
// has a null type).
val qualSym = qual.tpe.widen.typeSymbol
if (isAccessible(qualSym) && !qualSym.isPackageClass && !qualSym.isPackageObjectClass) {
// insert cast to prevent illegal access error (see #4283)
// util.trace("insert erasure cast ") (*/
treeCopy.Select(tree, gen.mkAttributedCast(qual, qual.tpe.widen), name) //)
} else tree
}
} else tree
case Template(parents, self, body) =>
assert(!currentOwner.isImplClass)
//Console.println("checking no dble defs " + tree)//DEBUG
checkNoDoubleDefs(tree.symbol.owner)
treeCopy.Template(tree, parents, noSelfType, addBridges(body, currentOwner))
case Match(selector, cases) =>
Match(Typed(selector, TypeTree(selector.tpe)), cases)
case Literal(ct) if ct.tag == ClazzTag
&& ct.typeValue.typeSymbol != definitions.UnitClass =>
val erased = ct.typeValue match {
case tr @ TypeRef(_, clazz, _) if clazz.isDerivedValueClass => scalaErasure.eraseNormalClassRef(tr)
case tpe => specialScalaErasure(tpe)
}
treeCopy.Literal(tree, Constant(erased))
case ClassDef(_,_,_,_) =>
debuglog("defs of " + tree.symbol + " = " + tree.symbol.info.decls)
copyClassDef(tree)(tparams = Nil)
case DefDef(_,_,_,_,_,_) =>
copyDefDef(tree)(tparams = Nil)
case TypeDef(_, _, _, _) =>
EmptyTree
case _ =>
tree
}
override def transform(tree: Tree): Tree = {
// Reply to "!!! needed?" which adorned the next line: without it, build fails with:
// Exception in thread "main" scala.tools.nsc.symtab.Types$TypeError:
// value array_this is not a member of object scala.runtime.ScalaRunTime
//
// What the heck is array_this? See preTransformer in this file:
// gen.mkRuntimeCall("array_"+name, qual :: args)
if (tree.symbol == ArrayClass && !tree.isType) tree
else {
val tree1 = preErase(tree)
tree1 match {
case EmptyTree | TypeTree() =>
tree1 setType specialScalaErasure(tree1.tpe)
case ArrayValue(elemtpt, trees) =>
treeCopy.ArrayValue(
tree1, elemtpt setType specialScalaErasure.applyInArray(elemtpt.tpe), trees map transform).clearType()
case DefDef(_, _, _, _, tpt, _) =>
try super.transform(tree1).clearType()
finally tpt setType specialErasure(tree1.symbol)(tree1.symbol.tpe).resultType
case _ =>
super.transform(tree1).clearType()
}
}
}
}
/** The main transform function: Pretransfom the tree, and then
* re-type it at phase erasure.next.
*/
override def transform(tree: Tree): Tree = {
val tree1 = preTransformer.transform(tree)
// log("tree after pretransform: "+tree1)
exitingErasure {
val tree2 = mixinTransformer.transform(tree1)
// debuglog("tree after addinterfaces: \n" + tree2)
newTyper(rootContext(unit, tree, erasedTypes = true)).typed(tree2)
}
}
}
final def resolveAnonymousBridgeClash(sym: Symbol, bridge: Symbol) {
// TODO reinstate this after Delambdafy generates anonymous classes that meet this requirement.
// require(sym.owner.isAnonymousClass, sym.owner)
log(s"Expanding name of ${sym.debugLocationString} as it clashes with bridge. Renaming deemed safe because the owner is anonymous.")
sym.expandName(sym.owner)
bridge.resetFlag(BRIDGE)
}
private class TypeRefAttachment(val tpe: TypeRef)
}
Other Scala source code examplesHere is a short list of links related to this Scala Erasure.scala source code file: |
The search page
Other Scala source code examples at this package level
Click here to learn more about this project
