diff options
Diffstat (limited to 'src/compiler/scala/tools/nsc/transform/Constructors.scala')
| -rw-r--r-- | src/compiler/scala/tools/nsc/transform/Constructors.scala | 624 |
1 files changed, 345 insertions, 279 deletions
diff --git a/src/compiler/scala/tools/nsc/transform/Constructors.scala b/src/compiler/scala/tools/nsc/transform/Constructors.scala index b2aac587eb..231a3e4c64 100644 --- a/src/compiler/scala/tools/nsc/transform/Constructors.scala +++ b/src/compiler/scala/tools/nsc/transform/Constructors.scala @@ -6,15 +6,14 @@ package scala.tools.nsc package transform -import scala.collection.{ mutable, immutable } -import scala.collection.mutable.ListBuffer +import scala.collection.mutable import scala.reflect.internal.util.ListOfNil import symtab.Flags._ /** This phase converts classes with parameters into Java-like classes with * fields, which are assigned to from constructors. */ -abstract class Constructors extends Statics with Transform with ast.TreeDSL { +abstract class Constructors extends Statics with Transform with TypingTransformers with ast.TreeDSL { import global._ import definitions._ @@ -27,8 +26,7 @@ abstract class Constructors extends Statics with Transform with ast.TreeDSL { private val guardedCtorStats: mutable.Map[Symbol, List[Tree]] = perRunCaches.newMap[Symbol, List[Tree]]() private val ctorParams: mutable.Map[Symbol, List[Symbol]] = perRunCaches.newMap[Symbol, List[Symbol]]() - class ConstructorTransformer(unit: CompilationUnit) extends Transformer { - + class ConstructorTransformer(unit: CompilationUnit) extends TypingTransformer(unit) { /* * Inspect for obvious out-of-order initialization; concrete, eager vals or vars, declared in this class, * for which a reference to the member precedes its definition. @@ -75,14 +73,17 @@ abstract class Constructors extends Statics with Transform with ast.TreeDSL { override def transform(tree: Tree): Tree = { tree match { - case cd @ ClassDef(mods0, name0, tparams0, impl0) if !cd.symbol.isInterface && !isPrimitiveValueClass(cd.symbol) => + case cd @ ClassDef(mods0, name0, tparams0, impl0) if !isPrimitiveValueClass(cd.symbol) && cd.symbol.primaryConstructor != NoSymbol => if(cd.symbol eq AnyValClass) { cd } else { checkUninitializedReads(cd) val tplTransformer = new TemplateTransformer(unit, impl0) - treeCopy.ClassDef(cd, mods0, name0, tparams0, tplTransformer.transformed) + tplTransformer.localTyper = this.localTyper + tplTransformer.atOwner(impl0, cd.symbol) { + treeCopy.ClassDef(cd, mods0, name0, tparams0, tplTransformer.transformed) + } } case _ => super.transform(tree) @@ -121,15 +122,15 @@ abstract class Constructors extends Statics with Transform with ast.TreeDSL { * What trees can be visited at this point? * To recap, by the time the constructors phase runs, local definitions have been hoisted out of their original owner. * Moreover, by the time elision is about to happen, the `intoConstructors` rewriting - * of template-level statements has taken place (the resulting trees can be found in `constrStatBuf`). + * of template-level statements has taken place (the resulting trees can be found in `constructorStats`). * * That means: * - * - nested classes are to be found in `defBuf` + * - nested classes are to be found in `defs` * - * - value and method definitions are also in `defBuf` and none of them contains local methods or classes. + * - value and method definitions are also in `defs` and none of them contains local methods or classes. * - * - auxiliary constructors are to be found in `auxConstructorBuf` + * - auxiliary constructors are to be found in `auxConstructors` * * Coming back to the question which trees may contain accesses: * @@ -148,62 +149,56 @@ abstract class Constructors extends Statics with Transform with ast.TreeDSL { * (the primary constructor) into a dedicated synthetic method that an anon-closure may invoke, as required by DelayedInit. * */ - private trait OmittablesHelper { self: TemplateTransformer => - - /* - * Initially populated with all elision candidates. - * Trees are traversed, and those candidates are removed which are actually needed. - * After that, `omittables` doesn't shrink anymore: each symbol it contains can be unlinked from clazz.info.decls. - */ - val omittables = mutable.Set.empty[Symbol] - - def populateOmittables() { - - omittables.clear() - - if(isDelayedInitSubclass) { - return - } - - def isParamCandidateForElision(sym: Symbol) = (sym.isParamAccessor && sym.isPrivateLocal) - def isOuterCandidateForElision(sym: Symbol) = (sym.isOuterAccessor && sym.owner.isEffectivelyFinal && !sym.isOverridingSymbol) - - val paramCandidatesForElision: Set[ /*Field*/ Symbol] = (clazz.info.decls.toSet filter isParamCandidateForElision) - val outerCandidatesForElision: Set[ /*Method*/ Symbol] = (clazz.info.decls.toSet filter isOuterCandidateForElision) - - omittables ++= paramCandidatesForElision - omittables ++= outerCandidatesForElision - - val bodyOfOuterAccessor: Map[Symbol, DefDef] = - defBuf.collect { case dd: DefDef if outerCandidatesForElision(dd.symbol) => dd.symbol -> dd }.toMap + private trait OmittablesHelper { + def computeOmittableAccessors(clazz: Symbol, defs: List[Tree], auxConstructors: List[Tree]): Set[Symbol] = { + val decls = clazz.info.decls.toSet + val isEffectivelyFinal = clazz.isEffectivelyFinal + + // Initially populated with all elision candidates. + // Trees are traversed, and those candidates are removed which are actually needed. + // After that, `omittables` doesn't shrink anymore: each symbol it contains can be unlinked from clazz.info.decls. + // + // Note: elision of outer reference is based on a class-wise analysis, if a class might have subclasses, + // it doesn't work. For example, `LocalParent` retains the outer reference in: + // + // class Outer { def test = {class LocalParent; class LocalChild extends LocalParent } } + // + // See run/t9408.scala for related test cases. + def omittableParamAcc(sym: Symbol) = sym.isParamAccessor && sym.isPrivateLocal + def omittableOuterAcc(sym: Symbol) = isEffectivelyFinal && sym.isOuterAccessor && !sym.isOverridingSymbol + val omittables = mutable.Set.empty[Symbol] ++ (decls filter (sym => omittableParamAcc(sym) || omittableOuterAcc(sym))) // the closure only captures isEffectivelyFinal // no point traversing further once omittables is empty, all candidates ruled out already. object detectUsages extends Traverser { - private def markUsage(sym: Symbol) { - omittables -= debuglogResult("omittables -= ")(sym) - // recursive call to mark as needed the field supporting the outer-accessor-method. - bodyOfOuterAccessor get sym foreach (this traverse _.rhs) - } - override def traverse(tree: Tree): Unit = if (omittables.nonEmpty) { - def sym = tree.symbol - tree match { - // don't mark as "needed" the field supporting this outer-accessor, ie not just yet. - case _: DefDef if outerCandidatesForElision(sym) => () - case _: Select if omittables(sym) => markUsage(sym) ; super.traverse(tree) - case _ => super.traverse(tree) + lazy val bodyOfOuterAccessor = defs.collect{ case dd: DefDef if omittableOuterAcc(dd.symbol) => dd.symbol -> dd.rhs }.toMap + + override def traverse(tree: Tree): Unit = + if (omittables.nonEmpty) { + def sym = tree.symbol + tree match { + case _: DefDef if (sym.owner eq clazz) && omittableOuterAcc(sym) => // don't mark as "needed" the field supporting this outer-accessor (not just yet) + case _: Select if omittables(sym) => omittables -= sym // mark usage + bodyOfOuterAccessor get sym foreach traverse // recurse to mark as needed the field supporting the outer-accessor-method + super.traverse(tree) + case _ => super.traverse(tree) + } } - } - def walk(xs: Seq[Tree]) = xs.iterator foreach traverse - } - if (omittables.nonEmpty) { - detectUsages walk defBuf - detectUsages walk auxConstructorBuf } - } - def mustBeKept(sym: Symbol) = !omittables(sym) + if (omittables.nonEmpty) + (defs.iterator ++ auxConstructors.iterator) foreach detectUsages.traverse + + omittables.toSet + } } // OmittablesHelper + trait ConstructorTransformerBase { + def unit: CompilationUnit + def impl: Template + def clazz: Symbol + def localTyper: analyzer.Typer + } + /* * TemplateTransformer rewrites DelayedInit subclasses. * The list of statements that will end up in the primary constructor can be split into: @@ -248,10 +243,8 @@ abstract class Constructors extends Statics with Transform with ast.TreeDSL { * @return the DefDef for (c) above * * */ - private trait DelayedInitHelper { self: TemplateTransformer => - + private trait DelayedInitHelper extends ConstructorTransformerBase { private def delayedEndpointDef(stats: List[Tree]): DefDef = { - val methodName = currentUnit.freshTermName("delayedEndpoint$" + clazz.fullNameAsName('$').toString + "$") val methodSym = clazz.newMethod(methodName, impl.pos, SYNTHETIC | FINAL) methodSym setInfoAndEnter MethodType(Nil, UnitTpe) @@ -310,36 +303,30 @@ abstract class Constructors extends Statics with Transform with ast.TreeDSL { satelliteClass.asInstanceOf[ClassDef] } - private def delayedInitCall(closure: Tree) = localTyper.typedPos(impl.pos) { - gen.mkMethodCall(This(clazz), delayedInitMethod, Nil, List(New(closure.symbol.tpe, This(clazz)))) - } + /** For a DelayedInit subclass, wrap remainingConstrStats into a DelayedInit closure. */ + def delayedInitDefsAndConstrStats(defs: List[Tree], remainingConstrStats: List[Tree]): (List[Tree], List[Tree]) = { + val delayedHook = delayedEndpointDef(remainingConstrStats) + val delayedHookSym = delayedHook.symbol.asInstanceOf[MethodSymbol] - def rewriteDelayedInit() { - /* XXX This is not correct: remainingConstrStats.nonEmpty excludes too much, - * but excluding it includes too much. The constructor sequence being mimicked - * needs to be reproduced with total fidelity. - * - * See test case files/run/bug4680.scala, the output of which is wrong in many - * particulars. - */ - val needsDelayedInit = (isDelayedInitSubclass && remainingConstrStats.nonEmpty) - - if (needsDelayedInit) { - val delayedHook: DefDef = delayedEndpointDef(remainingConstrStats) - defBuf += delayedHook - val hookCallerClass = { - // transform to make the closure-class' default constructor assign the outer instance to its param-accessor field. - val drillDown = new ConstructorTransformer(unit) - drillDown transform delayedInitClosure(delayedHook.symbol.asInstanceOf[MethodSymbol]) - } - defBuf += hookCallerClass - remainingConstrStats = delayedInitCall(hookCallerClass) :: Nil + // transform to make the closure-class' default constructor assign the outer instance to its param-accessor field. + val hookCallerClass = (new ConstructorTransformer(unit)) transform delayedInitClosure(delayedHookSym) + val delayedInitCall = localTyper.typedPos(impl.pos) { + gen.mkMethodCall(This(clazz), delayedInitMethod, Nil, List(New(hookCallerClass.symbol.tpe, This(clazz)))) } + + (List(delayedHook, hookCallerClass), List(delayedInitCall)) } } // DelayedInitHelper - private trait GuardianOfCtorStmts { self: TemplateTransformer => + private trait GuardianOfCtorStmts extends ConstructorTransformerBase { + def primaryConstrParams: List[Symbol] + def usesSpecializedField: Boolean + + lazy val hasSpecializedFieldsSym = clazz.info.decl(nme.SPECIALIZED_INSTANCE) + // The constructor of a non-specialized class that has specialized subclasses + // should use `q"${hasSpecializedFieldsSym}()"` to guard the initialization of specialized fields. + lazy val guardSpecializedFieldInit = (hasSpecializedFieldsSym != NoSymbol) && !clazz.hasFlag(SPECIALIZED) /* Return a single list of statements, merging the generic class constructor with the * specialized stats. The original statements are retyped in the current class, and @@ -347,7 +334,7 @@ abstract class Constructors extends Statics with Transform with ast.TreeDSL { * `specializedStats` are replaced by the specialized assignment. */ private def mergeConstructors(genericClazz: Symbol, originalStats: List[Tree], specializedStats: List[Tree]): List[Tree] = { - val specBuf = new ListBuffer[Tree] + val specBuf = new mutable.ListBuffer[Tree] specBuf ++= specializedStats def specializedAssignFor(sym: Symbol): Option[Tree] = @@ -375,7 +362,7 @@ abstract class Constructors extends Statics with Transform with ast.TreeDSL { } log("merging: " + originalStats.mkString("\n") + "\nwith\n" + specializedStats.mkString("\n")) - val res = for (s <- originalStats; stat = s.duplicate) yield { + for (s <- originalStats; stat = s.duplicate) yield { log("merge: looking at " + stat) val stat1 = stat match { case Assign(sel @ Select(This(_), field), _) => @@ -388,9 +375,9 @@ abstract class Constructors extends Statics with Transform with ast.TreeDSL { } if (stat1 eq stat) { - assert(ctorParams(genericClazz).length == constrInfo.constrParams.length) + assert(ctorParams(genericClazz).length == primaryConstrParams.length) // this is just to make private fields public - (new specializeTypes.ImplementationAdapter(ctorParams(genericClazz), constrInfo.constrParams, null, true))(stat1) + (new specializeTypes.ImplementationAdapter(ctorParams(genericClazz), primaryConstrParams, null, true))(stat1) val stat2 = rewriteArrayUpdate(stat1) // statements coming from the original class need retyping in the current context @@ -405,9 +392,8 @@ abstract class Constructors extends Statics with Transform with ast.TreeDSL { } else stat1 } - if (specBuf.nonEmpty) - println("residual specialized constructor statements: " + specBuf) - res +// if (specBuf.nonEmpty) +// println("residual specialized constructor statements: " + specBuf) } /* Add an 'if' around the statements coming after the super constructor. This @@ -427,16 +413,16 @@ abstract class Constructors extends Statics with Transform with ast.TreeDSL { // postfix = postfix.tail // } - if (shouldGuard && usesSpecializedField && stats.nonEmpty) { + if (guardSpecializedFieldInit && usesSpecializedField && stats.nonEmpty) { // save them for duplication in the specialized subclass guardedCtorStats(clazz) = stats - ctorParams(clazz) = constrInfo.constrParams + ctorParams(clazz) = primaryConstrParams val tree = If( Apply( CODE.NOT ( - Apply(gen.mkAttributedRef(specializedFlag), List())), + Apply(gen.mkAttributedRef(hasSpecializedFieldsSym), List())), List()), Block(stats, Literal(Constant(()))), EmptyTree) @@ -459,39 +445,31 @@ abstract class Constructors extends Statics with Transform with ast.TreeDSL { } // GuardianOfCtorStmts private class TemplateTransformer(val unit: CompilationUnit, val impl: Template) - extends StaticsTransformer + extends TypingTransformer(unit) + with StaticsTransformer with DelayedInitHelper with OmittablesHelper - with GuardianOfCtorStmts { - - val clazz = impl.symbol.owner // the transformed class - val stats = impl.body // the transformed template body - val localTyper = typer.atOwner(impl, clazz) - - val specializedFlag: Symbol = clazz.info.decl(nme.SPECIALIZED_INSTANCE) - val shouldGuard = (specializedFlag != NoSymbol) && !clazz.hasFlag(SPECIALIZED) - - val isDelayedInitSubclass = (clazz isSubClass DelayedInitClass) - - case class ConstrInfo( - constr: DefDef, // The primary constructor - constrParams: List[Symbol], // ... and its parameters - constrBody: Block // ... and its body - ) - // decompose primary constructor into the three entities above. - val constrInfo: ConstrInfo = { - val ddef = (stats find (_.symbol.isPrimaryConstructor)) - ddef match { - case Some(ddef @ DefDef(_, _, _, List(vparams), _, rhs @ Block(_, _))) => - ConstrInfo(ddef, vparams map (_.symbol), rhs) - case x => - abort("no constructor in template: impl = " + impl) - } + with GuardianOfCtorStmts + with fields.CheckedAccessorTreeSynthesis + { + protected def typedPos(pos: Position)(tree: Tree): Tree = localTyper.typedPos(pos)(tree) + + val clazz = impl.symbol.owner // the transformed class + + val isDelayedInitSubclass = clazz isSubClass DelayedInitClass + + private val stats = impl.body // the transformed template body + + // find and dissect primary constructor + private val (primaryConstr, _primaryConstrParams, primaryConstrBody) = stats collectFirst { + case dd@DefDef(_, _, _, vps :: Nil, _, rhs: Block) if dd.symbol.isPrimaryConstructor => (dd, vps map (_.symbol), rhs) + } getOrElse { + abort("no constructor in template: impl = " + impl) } - import constrInfo._ - // The parameter accessor fields which are members of the class - val paramAccessors = clazz.constrParamAccessors + + def primaryConstrParams = _primaryConstrParams + def usesSpecializedField = intoConstructor.usesSpecializedField // The constructor parameter corresponding to an accessor def parameter(acc: Symbol): Symbol = parameterNamed(acc.unexpandedName.getterName) @@ -501,27 +479,26 @@ abstract class Constructors extends Statics with Transform with ast.TreeDSL { def parameterNamed(name: Name): Symbol = { def matchesName(param: Symbol) = param.name == name || param.name.startsWith(name + nme.NAME_JOIN_STRING) - (constrParams filter matchesName) match { - case Nil => abort(name + " not in " + constrParams) + primaryConstrParams filter matchesName match { + case Nil => abort(name + " not in " + primaryConstrParams) case p :: _ => p } } - /* - * `usesSpecializedField` makes a difference in deciding whether constructor-statements - * should be guarded in a `shouldGuard` class, ie in a class that's the generic super-class of - * one or more specialized sub-classes. - * - * Given that `usesSpecializedField` isn't read for any other purpose than the one described above, - * we skip setting `usesSpecializedField` in case the current class isn't `shouldGuard` to start with. - * That way, trips to a map in `specializeTypes` are saved. - */ - var usesSpecializedField: Boolean = false - // A transformer for expressions that go into the constructor - private class IntoCtorTransformer extends Transformer { - - private def isParamRef(sym: Symbol) = (sym.isParamAccessor && sym.owner == clazz) + object intoConstructor extends Transformer { + /* + * `usesSpecializedField` makes a difference in deciding whether constructor-statements + * should be guarded in a `guardSpecializedFieldInit` class, ie in a class that's the generic super-class of + * one or more specialized sub-classes. + * + * Given that `usesSpecializedField` isn't read for any other purpose than the one described above, + * we skip setting `usesSpecializedField` in case the current class isn't `guardSpecializedFieldInit` to start with. + * That way, trips to a map in `specializeTypes` are saved. + */ + var usesSpecializedField: Boolean = false + + private def isParamRef(sym: Symbol) = sym.isParamAccessor && sym.owner == clazz // Terminology: a stationary location is never written after being read. private def isStationaryParamRef(sym: Symbol) = ( @@ -530,26 +507,27 @@ abstract class Constructors extends Statics with Transform with ast.TreeDSL { !sym.isSetter ) - private def possiblySpecialized(s: Symbol) = specializeTypes.specializedTypeVars(s).nonEmpty - /* - * whether `sym` denotes a param-accessor (ie a field) that fulfills all of: + * whether `sym` denotes a param-accessor (ie in a class a PARAMACCESSOR field, or in a trait a method with same flag) + * that fulfills all of: * (a) has stationary value, ie the same value provided via the corresponding ctor-arg; and * (b) isn't subject to specialization. We might be processing statements for: * (b.1) the constructor in the generic (super-)class; or * (b.2) the constructor in the specialized (sub-)class. * (c) isn't part of a DelayedInit subclass. */ - private def canBeSupplanted(sym: Symbol) = (!isDelayedInitSubclass && isStationaryParamRef(sym) && !possiblySpecialized(sym)) + private def canBeSupplanted(sym: Symbol) = !isDelayedInitSubclass && isStationaryParamRef(sym) && !specializeTypes.possiblySpecialized(sym) override def transform(tree: Tree): Tree = tree match { - case Apply(Select(This(_), _), List()) => // references to parameter accessor methods of own class become references to parameters // outer accessors become references to $outer parameter - if (canBeSupplanted(tree.symbol)) - gen.mkAttributedIdent(parameter(tree.symbol.accessed)) setPos tree.pos - else if (tree.symbol.outerSource == clazz && !clazz.isImplClass) + // println(s"to param ref in $clazz for ${tree.symbol} ${tree.symbol.debugFlagString} / ${tree.symbol.outerSource} / ${canBeSupplanted(tree.symbol)}") + if (clazz.isTrait && !(tree.symbol hasAllFlags (ACCESSOR | PARAMACCESSOR))) + super.transform(tree) + else if (canBeSupplanted(tree.symbol)) + gen.mkAttributedIdent(parameter(tree.symbol)) setPos tree.pos + else if (tree.symbol.outerSource == clazz && !isDelayedInitSubclass) gen.mkAttributedIdent(parameterNamed(nme.OUTER)) setPos tree.pos else super.transform(tree) @@ -558,8 +536,8 @@ abstract class Constructors extends Statics with Transform with ast.TreeDSL { // references to parameter accessor field of own class become references to parameters gen.mkAttributedIdent(parameter(tree.symbol)) setPos tree.pos - case Select(_, _) if shouldGuard => // reasoning behind this guard in the docu of `usesSpecializedField` - if (possiblySpecialized(tree.symbol)) { + case Select(_, _) if guardSpecializedFieldInit => // reasoning behind this guard in the docu of `usesSpecializedField` + if (specializeTypes.possiblySpecialized(tree.symbol)) { usesSpecializedField = true } super.transform(tree) @@ -568,23 +546,20 @@ abstract class Constructors extends Statics with Transform with ast.TreeDSL { super.transform(tree) } + // Move tree into constructor, take care of changing owner from `oldOwner` to `newOwner` (the primary constructor symbol) + def apply(oldOwner: Symbol, newOwner: Symbol)(tree: Tree) = + if (tree eq EmptyTree) tree + else transform(tree.changeOwner(oldOwner -> newOwner)) } - private val intoConstructorTransformer = new IntoCtorTransformer - - // Move tree into constructor, take care of changing owner from `oldowner` to constructor symbol - def intoConstructor(oldowner: Symbol, tree: Tree) = - intoConstructorTransformer transform tree.changeOwner(oldowner -> constr.symbol) - - // Should tree be moved in front of super constructor call? - def canBeMoved(tree: Tree) = tree match { - case ValDef(mods, _, _, _) => (mods hasFlag PRESUPER | PARAMACCESSOR) - case _ => false - } + // Assign `rhs` to class field / trait setter `assignSym` + def mkAssign(assignSym: Symbol, rhs: Tree): Tree = + localTyper.typedPos(assignSym.pos) { + val qual = Select(This(clazz), assignSym) + if (assignSym.isSetter) Apply(qual, List(rhs)) + else Assign(qual, rhs) + } - // Create an assignment to class field `to` with rhs `from` - def mkAssign(to: Symbol, from: Tree): Tree = - localTyper.typedPos(to.pos) { Assign(Select(This(clazz), to), from) } // Create code to copy parameter to parameter accessor field. // If parameter is $outer, check that it is not null so that we NPE @@ -594,139 +569,230 @@ abstract class Constructors extends Statics with Transform with ast.TreeDSL { val result = mkAssign(to, Ident(from)) if (from.name != nme.OUTER || - from.tpe.typeSymbol.isPrimitiveValueClass) result + from.tpe.typeSymbol.isPrimitiveValueClass) result else localTyper.typedPos(to.pos) { // `throw null` has the same effect as `throw new NullPointerException`, see JVM spec on instruction `athrow` - IF (from OBJ_EQ NULL) THEN Throw(gen.mkZero(ThrowableTpe)) ELSE result + IF(from OBJ_EQ NULL) THEN Throw(gen.mkZero(ThrowableTpe)) ELSE result } } - // The list of definitions that go into class - val defBuf = new ListBuffer[Tree] - - // The auxiliary constructors, separate from the defBuf since they should - // follow the primary constructor - val auxConstructorBuf = new ListBuffer[Tree] - - // The list of statements that go into the constructor after and including the superclass constructor call - val constrStatBuf = new ListBuffer[Tree] + /** Triage definitions and statements in this template into the following categories. + * The primary constructor is treated separately, as it is assembled in part from these pieces. + * + * - `defs`: definitions that go into class + * - `auxConstrs`: auxiliary constructors, separate from the defs as they should follow the primary constructor + * - `constrPrefix`: early initializer statements that go into constructor before the superclass constructor call + * - `constrStats`: statements that go into the constructor after and including the superclass constructor call + * - `classInitStats`: statements that go into the class initializer + */ + class Triage { + private val defBuf, auxConstructorBuf, constrPrefixBuf, constrStatBuf, classInitStatBuf = new mutable.ListBuffer[Tree] + + triage() + + val defs = defBuf.toList + val auxConstructors = auxConstructorBuf.toList + val constructorPrefix = constrPrefixBuf.toList + val constructorStats = constrStatBuf.toList + val classInitStats = classInitStatBuf.toList + + private def triage() = { + // Constant typed vals are not memoized. + def memoizeValue(sym: Symbol) = !sym.info.resultType.isInstanceOf[ConstantType] + + // The early initialized field definitions of the class (these are the class members) + val presupers = treeInfo.preSuperFields(stats) + + // generate code to copy pre-initialized fields + for (stat <- primaryConstrBody.stats) { + constrStatBuf += stat + stat match { + case ValDef(mods, name, _, _) if mods.hasFlag(PRESUPER) => // TODO trait presupers + // stat is the constructor-local definition of the field value + val fields = presupers filter (_.getterName == name) + assert(fields.length == 1, s"expected exactly one field by name $name in $presupers of $clazz's early initializers") + val to = fields.head.symbol + + if (memoizeValue(to)) constrStatBuf += mkAssign(to, Ident(stat.symbol)) + case _ => + } + } - // The list of early initializer statements that go into constructor before the superclass constructor call - val constrPrefixBuf = new ListBuffer[Tree] + val primaryConstrSym = primaryConstr.symbol + + for (stat <- stats) { + val statSym = stat.symbol + + // Move the RHS of a ValDef to the appropriate part of the ctor. + // If the val is an early initialized or a parameter accessor, + // it goes before the superclass constructor call, otherwise it goes after. + // A lazy val's effect is not moved to the constructor, as it is delayed. + // Returns `true` when a `ValDef` is needed. + def moveEffectToCtor(mods: Modifiers, rhs: Tree, assignSym: Symbol): Unit = { + val initializingRhs = + if ((assignSym eq NoSymbol) || statSym.isLazy) EmptyTree // not memoized, or effect delayed (for lazy val) + else if (!mods.hasStaticFlag) intoConstructor(statSym, primaryConstrSym)(rhs) + else rhs + + if (initializingRhs ne EmptyTree) { + val initPhase = + if (mods hasFlag STATIC) classInitStatBuf + else if (mods hasFlag PRESUPER | PARAMACCESSOR) constrPrefixBuf + else constrStatBuf + + initPhase += mkAssign(assignSym, initializingRhs) + } + } - // The early initialized field definitions of the class (these are the class members) - val presupers = treeInfo.preSuperFields(stats) + stat match { + // recurse on class definition, store in defBuf + case _: ClassDef => + if (statSym.isInterface) defBuf += stat + else defBuf += new ConstructorTransformer(unit).transform(stat) + + // primary constructor is already tracked as `primaryConstr` + // non-primary constructors go to auxConstructorBuf + case _: DefDef if statSym.isConstructor => + if (statSym ne primaryConstrSym) auxConstructorBuf += stat + + // If a val needs a field, an empty valdef goes into the template. + // Except for lazy and ConstantTyped vals, the field is initialized by an assignment in: + // - the class initializer (static), + // - the constructor, before the super call (early initialized or a parameter accessor), + // - the constructor, after the super call (regular val). + case vd: ValDef => + if (vd.rhs eq EmptyTree) { defBuf += vd } + else { + val emitField = memoizeValue(statSym) + + if (emitField) { + moveEffectToCtor(vd.mods, vd.rhs, statSym) + defBuf += deriveValDef(stat)(_ => EmptyTree) + } + } - // The list of statements that go into the class initializer - val classInitStatBuf = new ListBuffer[Tree] + case dd: DefDef => + // either move the RHS to ctor (for getter of stored field) or just drop it (for corresponding setter) + def shouldMoveRHS = + clazz.isTrait && statSym.isAccessor && !statSym.isLazy && (statSym.isSetter || memoizeValue(statSym)) - // generate code to copy pre-initialized fields - for (stat <- constrBody.stats) { - constrStatBuf += stat - stat match { - case ValDef(mods, name, _, _) if (mods hasFlag PRESUPER) => - // stat is the constructor-local definition of the field value - val fields = presupers filter (_.getterName == name) - assert(fields.length == 1) - val to = fields.head.symbol - if (!to.tpe.isInstanceOf[ConstantType]) - constrStatBuf += mkAssign(to, Ident(stat.symbol)) - case _ => - } - } + if ((dd.rhs eq EmptyTree) || !shouldMoveRHS) { defBuf += dd } + else { + if (statSym.isGetter) moveEffectToCtor(dd.mods, dd.rhs, statSym.asTerm.referenced orElse statSym.setterIn(clazz)) + defBuf += deriveDefDef(stat)(_ => EmptyTree) + } - // Triage all template definitions to go into defBuf/auxConstructorBuf, constrStatBuf, or constrPrefixBuf. - for (stat <- stats) stat match { - case DefDef(_,_,_,_,_,rhs) => - // methods with constant result type get literals as their body - // all methods except the primary constructor go into template - stat.symbol.tpe match { - case MethodType(List(), tp @ ConstantType(c)) => - defBuf += deriveDefDef(stat)(Literal(c) setPos _.pos setType tp) - case _ => - if (stat.symbol.isPrimaryConstructor) () - else if (stat.symbol.isConstructor) auxConstructorBuf += stat - else defBuf += stat - } - case ValDef(mods, _, _, rhs) if !mods.hasStaticFlag => - // val defs with constant right-hand sides are eliminated. - // for all other val defs, an empty valdef goes into the template and - // the initializer goes as an assignment into the constructor - // if the val def is an early initialized or a parameter accessor, it goes - // before the superclass constructor call, otherwise it goes after. - // Lazy vals don't get the assignment in the constructor. - if (!stat.symbol.tpe.isInstanceOf[ConstantType]) { - if (rhs != EmptyTree && !stat.symbol.isLazy) { - val rhs1 = intoConstructor(stat.symbol, rhs) - (if (canBeMoved(stat)) constrPrefixBuf else constrStatBuf) += mkAssign( - stat.symbol, rhs1) + // all other statements go into the constructor + case _ => + constrStatBuf += intoConstructor(impl.symbol, primaryConstrSym)(stat) } - defBuf += deriveValDef(stat)(_ => EmptyTree) } - case ValDef(_, _, _, rhs) => - // Add static initializer statements to classInitStatBuf and remove the rhs from the val def. - classInitStatBuf += mkAssign(stat.symbol, rhs) - defBuf += deriveValDef(stat)(_ => EmptyTree) - - case ClassDef(_, _, _, _) => - // classes are treated recursively, and left in the template - defBuf += new ConstructorTransformer(unit).transform(stat) - case _ => - // all other statements go into the constructor - constrStatBuf += intoConstructor(impl.symbol, stat) - } - - populateOmittables() - - // Initialize all parameters fields that must be kept. - val paramInits = paramAccessors filter mustBeKept map { acc => - // Check for conflicting symbol amongst parents: see bug #1960. - // It would be better to mangle the constructor parameter name since - // it can only be used internally, but I think we need more robust name - // mangling before we introduce more of it. - val conflict = clazz.info.nonPrivateMember(acc.name) filter (s => s.isGetter && !s.isOuterField && s.enclClass.isTrait) - if (conflict ne NoSymbol) - reporter.error(acc.pos, "parameter '%s' requires field but conflicts with %s".format(acc.name, conflict.fullLocationString)) - - copyParam(acc, parameter(acc)) - } - - /* Return a pair consisting of (all statements up to and including superclass and trait constr calls, rest) */ - def splitAtSuper(stats: List[Tree]) = { - def isConstr(tree: Tree): Boolean = tree match { - case Block(_, expr) => isConstr(expr) // SI-6481 account for named argument blocks - case _ => (tree.symbol ne null) && tree.symbol.isConstructor } - val (pre, rest0) = stats span (!isConstr(_)) - val (supercalls, rest) = rest0 span (isConstr(_)) - (pre ::: supercalls, rest) } - val (uptoSuperStats, remainingConstrStats0) = splitAtSuper(constrStatBuf.toList) - var remainingConstrStats = remainingConstrStats0 - - rewriteDelayedInit() + def transformed = { + val triage = new Triage; import triage._ + + // omit unused outers + val omittableAccessor: Set[Symbol] = + if (isDelayedInitSubclass) Set.empty + else computeOmittableAccessors(clazz, defs, auxConstructors) + + // TODO: this should omit fields for non-memoized (constant-typed, unit-typed vals need no storage -- + // all the action is in the getter) + def omittableSym(sym: Symbol) = omittableAccessor(sym) + def omittableStat(stat: Tree) = omittableSym(stat.symbol) + + // The parameter accessor fields which are members of the class + val paramAccessors = + if (clazz.isTrait) clazz.info.decls.toList.filter(sym => sym.hasAllFlags(STABLE | PARAMACCESSOR)) // since a trait does not have constructor parameters (yet), these can only come from lambdalift -- right? + else clazz.constrParamAccessors + + // Initialize all parameters fields that must be kept. + val paramInits = paramAccessors filterNot omittableSym map { acc => + // Check for conflicting field mixed in for a val/var defined in a parent trait (neg/t1960.scala). + // Since the fields phase has already mixed in fields, we can just look for + // an existing decl with the local variant of our paramaccessor's name. + // + // TODO: mangle the constructor parameter name (it can only be used internally), though we probably first need more robust name mangling + + // sometimes acc is a field with a local name (when it's a val/var constructor param) --> exclude the `acc` itself when looking for conflicting decl + // sometimes it's not (just a constructor param) --> any conflicting decl is a problem + val conflict = clazz.info.decl(acc.name.localName).filter(sym => sym ne acc) + if (conflict ne NoSymbol) { + val orig = exitingTyper(clazz.info.nonPrivateMember(acc.name).filter(_ hasFlag ACCESSOR)) + reporter.error(acc.pos, s"parameter '${acc.name}' requires field but conflicts with ${(orig orElse conflict).fullLocationString}") + } - // Assemble final constructor - defBuf += deriveDefDef(constr)(_ => - treeCopy.Block( - constrBody, - paramInits ::: constrPrefixBuf.toList ::: uptoSuperStats ::: - guardSpecializedInitializer(remainingConstrStats), - constrBody.expr)) + val accSetter = + if (clazz.isTrait) acc.setterIn(clazz, hasExpandedName = true) + else acc - // Followed by any auxiliary constructors - defBuf ++= auxConstructorBuf + copyParam(accSetter, parameter(acc)) + } - // Unlink all fields that can be dropped from class scope - for (sym <- clazz.info.decls ; if !mustBeKept(sym)) - clazz.info.decls unlink sym + // Return a pair consisting of (all statements up to and including superclass and trait constr calls, rest) + def splitAtSuper(stats: List[Tree]) = { + def isConstr(tree: Tree): Boolean = tree match { + case Block(_, expr) => isConstr(expr) // SI-6481 account for named argument blocks + case _ => (tree.symbol ne null) && tree.symbol.isConstructor + } + val (pre, rest0) = stats span (!isConstr(_)) + val (supercalls, rest) = rest0 span (isConstr(_)) + (pre ::: supercalls, rest) + } - // Eliminate all field definitions that can be dropped from template - val templateWithoutOmittables: Template = deriveTemplate(impl)(_ => defBuf.toList filter (stat => mustBeKept(stat.symbol))) - // Add the static initializers - val transformed: Template = addStaticInits(templateWithoutOmittables, classInitStatBuf, localTyper) + val (uptoSuperStats, remainingConstrStats) = splitAtSuper(constructorStats) + + /* TODO: XXX This condition (`isDelayedInitSubclass && remainingConstrStats.nonEmpty`) is not correct: + * remainingConstrStats.nonEmpty excludes too much, + * but excluding it includes too much. The constructor sequence being mimicked + * needs to be reproduced with total fidelity. + * + * See test case files/run/bug4680.scala, the output of which is wrong in many + * particulars. + */ + val (delayedHookDefs, remainingConstrStatsDelayedInit) = + if (isDelayedInitSubclass && remainingConstrStats.nonEmpty) delayedInitDefsAndConstrStats(defs, remainingConstrStats) + else (Nil, remainingConstrStats) + + // Assemble final constructor + val primaryConstructor = deriveDefDef(primaryConstr)(_ => { + treeCopy.Block( + primaryConstrBody, + paramInits ::: constructorPrefix ::: uptoSuperStats ::: guardSpecializedInitializer(remainingConstrStatsDelayedInit), + primaryConstrBody.expr) + }) + + if (omittableAccessor.exists(_.isOuterField) && !constructorStats.exists(_.exists { case i: Ident if i.symbol.isOuterParam => true; case _ => false})) + primaryConstructor.symbol.updateAttachment(OuterArgCanBeElided) + + val constructors = primaryConstructor :: auxConstructors + + // Unlink all fields that can be dropped from class scope + // Iterating on toList is cheaper (decls.filter does a toList anyway) + val decls = clazz.info.decls + decls.toList.filter(omittableSym).foreach(decls.unlink) + + // Eliminate all field/accessor definitions that can be dropped from template + // We never eliminate delayed hooks or the constructors, so, only filter `defs`. + val prunedStats = (defs filterNot omittableStat) ::: delayedHookDefs ::: constructors + + val statsWithInitChecks = + if (settings.checkInit) { + val addChecks = new SynthInitCheckedAccessorsIn(currentOwner) + prunedStats mapConserve { + case dd: DefDef => deriveDefDef(dd)(addChecks.wrapRhsWithInitChecks(dd.symbol)) + case stat => stat + } + } else prunedStats + // Add the static initializers + if (classInitStats.isEmpty) deriveTemplate(impl)(_ => statsWithInitChecks) + else { + val staticCtor = staticConstructor(statsWithInitChecks, localTyper, impl.pos)(classInitStats) + deriveTemplate(impl)(_ => staticCtor :: statsWithInitChecks) + } + } } // TemplateTransformer - } |