diff options
Diffstat (limited to 'src/compiler/scala/tools/nsc/typechecker/Typers.scala')
| -rw-r--r-- | src/compiler/scala/tools/nsc/typechecker/Typers.scala | 395 |
1 files changed, 273 insertions, 122 deletions
diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala index 7c76eff9d8..3f5a4036aa 100644 --- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala +++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala @@ -1378,13 +1378,6 @@ trait Typers extends Modes with Adaptations with Tags { if (member(qual, name) != NoSymbol) qual else adaptToMember(qual, HasMember(name)) - private def typePrimaryConstrBody(clazz : Symbol, cbody: Tree, tparams: List[Symbol], enclTparams: List[Symbol], vparamss: List[List[ValDef]]): Tree = { - // XXX: see about using the class's symbol.... - enclTparams foreach (sym => context.scope.enter(sym)) - namer.enterValueParams(vparamss) - typed(cbody) - } - private def validateNoCaseAncestor(clazz: Symbol) = { if (!phase.erasedTypes) { for (ancestor <- clazz.ancestors find (_.isCase)) { @@ -1486,125 +1479,263 @@ trait Typers extends Modes with Adaptations with Tags { unit.error(tparam.pos, "type parameter of value class may not be specialized") } - def parentTypes(templ: Template): List[Tree] = - if (templ.parents.isEmpty) List(atPos(templ.pos)(TypeTree(AnyRefClass.tpe))) - else try { - val clazz = context.owner - // Normalize supertype and mixins so that supertype is always a class, not a trait. - var supertpt = typedTypeConstructor(templ.parents.head) - val firstParent = supertpt.tpe.typeSymbol - var mixins = templ.parents.tail map typedType - // If first parent is a trait, make it first mixin and add its superclass as first parent - while ((supertpt.tpe.typeSymbol ne null) && supertpt.tpe.typeSymbol.initialize.isTrait) { - val supertpt1 = typedType(supertpt) - if (!supertpt1.isErrorTyped) { - mixins = supertpt1 :: mixins - supertpt = TypeTree(supertpt1.tpe.firstParent) setPos supertpt.pos.focus - } + /** Typechecks a parent type reference. + * + * This typecheck is harder than it might look, because it should honor early + * definitions and also perform type argument inference with the help of super call + * arguments provided in `encodedtpt`. + * + * The method is called in batches (batch = 1 time per each parent type referenced), + * two batches per definition: once from namer, when entering a ClassDef or a ModuleDef + * and once from typer, when typechecking the definition. + * + * ***Arguments*** + * + * `encodedtpt` represents the parent type reference wrapped in an `Apply` node + * which indicates value arguments (i.e. type macro arguments or super constructor call arguments) + * If no value arguments are provided by the user, the `Apply` node is still + * there, but its `args` will be set to `Nil`. + * This argument is synthesized by `tools.nsc.ast.Parsers.templateParents`. + * + * `templ` is an enclosing template, which contains a primary constructor synthesized by the parser. + * Such a constructor is a DefDef which contains early initializers and maybe a super constructor call + * (I wrote "maybe" because trait constructors don't call super constructors). + * This argument is synthesized by `tools.nsc.ast.Trees.Template`. + * + * `inMixinPosition` indicates whether the reference is not the first in the + * list of parents (and therefore cannot be a class) or the opposite. + * + * ***Return value and side effects*** + * + * Returns a `TypeTree` representing a resolved parent type. + * If the typechecked parent reference implies non-nullary and non-empty argument list, + * this argument list is attached to the returned value in SuperCallArgsAttachment. + * The attachment is necessary for the subsequent typecheck to fixup a super constructor call + * in the body of the primary constructor (see `typedTemplate` for details). + * + * This method might invoke `typedPrimaryConstrBody`, hence it might cause the side effects + * described in the docs of that method. It might also attribute the Super(_, _) reference + * (if present) inside the primary constructor of `templ`. + * + * ***Example*** + * + * For the following definition: + * + * class D extends { + * val x = 2 + * val y = 4 + * } with B(x)(3) with C(y) with T + * + * this method will be called six times: + * + * (3 times from the namer) + * typedParentType(Apply(Apply(Ident(B), List(Ident(x))), List(3)), templ, inMixinPosition = false) + * typedParentType(Apply(Ident(C), List(Ident(y))), templ, inMixinPosition = true) + * typedParentType(Apply(Ident(T), List()), templ, inMixinPosition = true) + * + * (3 times from the typer) + * <the same three calls> + */ + private def typedParentType(encodedtpt: Tree, templ: Template, inMixinPosition: Boolean): Tree = { + val app = treeInfo.dissectApplied(encodedtpt) + val (treeInfo.Applied(core, targs, argss), decodedtpt) = (app, app.callee) + val argssAreTrivial = argss == Nil || argss == ListOfNil + + // we cannot avoid cyclic references with `initialize` here, because when type macros arrive, + // we'll have to check the probe for isTypeMacro anyways. + // therefore I think it's reasonable to trade a more specific "inherits itself" error + // for a generic, yet understandable "cyclic reference" error + var probe = typedTypeConstructor(core.duplicate).tpe.typeSymbol + if (probe == null) probe = NoSymbol + probe.initialize + + if (probe.isTrait || inMixinPosition) { + if (!argssAreTrivial) { + if (probe.isTrait) ConstrArgsInParentWhichIsTraitError(encodedtpt, probe) + else () // a class in a mixin position - this warrants an error in `validateParentClasses` + // therefore here we do nothing, e.g. don't check that the # of ctor arguments + // matches the # of ctor parameters or stuff like that } - if (supertpt.tpe.typeSymbol == AnyClass && firstParent.isTrait) - supertpt.tpe = AnyRefClass.tpe - - // Determine - // - supertparams: Missing type parameters from supertype - // - supertpe: Given supertype, polymorphic in supertparams - val supertparams = if (supertpt.hasSymbol) supertpt.symbol.typeParams else List() - var supertpe = supertpt.tpe - if (!supertparams.isEmpty) - supertpe = PolyType(supertparams, appliedType(supertpe, supertparams map (_.tpeHK))) - - // A method to replace a super reference by a New in a supercall - def transformSuperCall(scall: Tree): Tree = (scall: @unchecked) match { - case Apply(fn, args) => - treeCopy.Apply(scall, transformSuperCall(fn), args map (_.duplicate)) - case Select(Super(_, _), nme.CONSTRUCTOR) => - treeCopy.Select( - scall, - atPos(supertpt.pos.focus)(New(TypeTree(supertpe)) setType supertpe), - nme.CONSTRUCTOR) + typedType(decodedtpt) + } else { + var supertpt = typedTypeConstructor(decodedtpt) + val supertparams = if (supertpt.hasSymbol) supertpt.symbol.typeParams else Nil + if (supertparams.nonEmpty) { + typedPrimaryConstrBody(templ) { superRef => + val supertpe = PolyType(supertparams, appliedType(supertpt.tpe, supertparams map (_.tpeHK))) + val supercall = New(supertpe, mmap(argss)(_.duplicate)) + val treeInfo.Applied(Select(ctor, nme.CONSTRUCTOR), _, _) = supercall + ctor setType supertpe // this is an essential hack, otherwise it will occasionally fail to typecheck + atPos(supertpt.pos.focus)(supercall) + } match { + case EmptyTree => MissingTypeArgumentsParentTpeError(supertpt) + case tpt => supertpt = TypeTree(tpt.tpe) setPos supertpt.pos.focus + } } + // this is the place where we tell the typer what argss should be used for the super call + // if argss are nullary or empty, then (see the docs for `typedPrimaryConstrBody`) + // the super call dummy is already good enough, so we don't need to do anything + if (argssAreTrivial) supertpt else supertpt updateAttachment SuperCallArgsAttachment(argss) + } + } - treeInfo.firstConstructor(templ.body) match { - case constr @ DefDef(_, _, _, vparamss, _, cbody @ Block(cstats, cunit)) => - // Convert constructor body to block in environment and typecheck it - val (preSuperStats, superCall) = { - val (stats, rest) = cstats span (x => !treeInfo.isSuperConstrCall(x)) - (stats map (_.duplicate), if (rest.isEmpty) EmptyTree else rest.head.duplicate) - } - val cstats1 = if (superCall == EmptyTree) preSuperStats else preSuperStats :+ superCall - val cbody1 = treeCopy.Block(cbody, preSuperStats, superCall match { - case Apply(_, _) if supertparams.nonEmpty => transformSuperCall(superCall) - case _ => cunit.duplicate - }) - val outercontext = context.outer - - assert(clazz != NoSymbol, templ) - val cscope = outercontext.makeNewScope(constr, outercontext.owner) - val cbody2 = newTyper(cscope) // called both during completion AND typing. - .typePrimaryConstrBody(clazz, - cbody1, supertparams, clazz.unsafeTypeParams, vparamss map (_.map(_.duplicate))) - - superCall match { - case Apply(_, _) => - val sarg = treeInfo.firstArgument(superCall) - if (sarg != EmptyTree && supertpe.typeSymbol != firstParent) - ConstrArgsInTraitParentTpeError(sarg, firstParent) - if (!supertparams.isEmpty) - supertpt = TypeTree(cbody2.tpe) setPos supertpt.pos.focus - case _ => - if (!supertparams.isEmpty) - MissingTypeArgumentsParentTpeError(supertpt) - } + /** Typechecks the mishmash of trees that happen to be stuffed into the primary constructor of a given template. + * Before commencing the typecheck applies `superCallTransform` to a super call (if the latter exists). + * The transform can return `EmptyTree`, in which case the super call is replaced with a literal unit. + * + * ***Return value and side effects*** + * + * If a super call is present in the primary constructor and is not erased by the transform, returns it typechecked. + * Otherwise (e.g. if the primary constructor is missing or the super call isn't there) returns `EmptyTree`. + * + * As a side effect, this method attributes the underlying fields of early vals. + * Early vals aren't typechecked anywhere else, so it's essential to call `typedPrimaryConstrBody` + * at least once per definition. It'd be great to disentangle this logic at some point. + * + * ***Example*** + * + * For the following definition: + * + * class D extends { + * val x = 2 + * val y = 4 + * } with B(x)(3) with C(y) with T + * + * the primary constructor of `templ` will be: + * + * Block(List( + * ValDef(NoMods, x, TypeTree(), 2) + * ValDef(NoMods, y, TypeTree(), 4) + * Apply(Select(Super(This(tpnme.EMPTY), tpnme.EMPTY), nme.CONSTRUCTOR)), List()), + * Literal(Constant(()))) + * + * Note the Select(Super(_, _), nme.CONSTRUCTOR) part. This is the representation of + * a fill-me-in-later supercall dummy. The argss are Nil, which encodes the fact + * that supercall argss are unknown during parsing and need to be transplanted from one of the parent types. + * Read more about why the argss are unknown in `tools.nsc.ast.Trees.Template`. + * + * The entire Apply(Select(Super(This(tpnme.EMPTY), tpnme.EMPTY), nme.CONSTRUCTOR)), List()) is a dummy, + * and it's the one and only possible representation that can be emitted by parser. + * + * Despite of being unwieldy, this tree is quite convenient because: + * * It works as is for the case when no processing is required (empty ctor args for the superclass) + * * Stripping off the Apply produces a core that only needs rewrapping with applications of actual argss. + * + * For some time I was thinking of using just Select(Super(This(tpnme.EMPTY), tpnme.EMPTY), nme.CONSTRUCTOR)), + * but that one required wrapping even if the superclass doesn't take any argss. + * + * Another option would be to introduce a singleton tree akin to `emptyValDef` and use it as a dummy. + * Unfortunately this won't work out of the box, because the Super part is supposed to get attributed + * during `typedPrimaryConstrBody`. + * + * We could introduce another attachment for that or change SuperCallArgsAttachment + * to accommodate for the attributed Super, and then using the attached info to adjust the primary constructor + * during typedTemplate. However, given the scope of necessary changes (beyond a few lines) and the fact that, + * according to Martin, the whole thing is to be rewritten soon, I'd say we don't do the follow-up refactoring. + */ + private def typedPrimaryConstrBody(templ: Template)(superCallTransform: Tree => Tree): Tree = + treeInfo.firstConstructor(templ.body) match { + case ctor @ DefDef(_, _, _, vparamss, _, cbody @ Block(cstats, cunit)) => + val (preSuperStats, superCall) = { + val (stats, rest) = cstats span (x => !treeInfo.isSuperConstrCall(x)) + (stats map (_.duplicate), if (rest.isEmpty) EmptyTree else rest.head.duplicate) + } + val superCall1 = (superCall match { + case Apply(superRef @ Select(Super(_, _), nme.CONSTRUCTOR), Nil) => superCallTransform(superRef) + case EmptyTree => EmptyTree + }) orElse cunit + val cbody1 = treeCopy.Block(cbody, preSuperStats, superCall1) + + val clazz = context.owner + assert(clazz != NoSymbol, templ) + val cscope = context.outer.makeNewScope(ctor, context.outer.owner) + val cbody2 = { // called both during completion AND typing. + val typer1 = newTyper(cscope) + // XXX: see about using the class's symbol.... + clazz.unsafeTypeParams foreach (sym => typer1.context.scope.enter(sym)) + typer1.namer.enterValueParams(vparamss map (_.map(_.duplicate))) + typer1.typed(cbody1) + } - val preSuperVals = treeInfo.preSuperFields(templ.body) - if (preSuperVals.isEmpty && preSuperStats.nonEmpty) - debugwarn("Wanted to zip empty presuper val list with " + preSuperStats) - else - map2(preSuperStats, preSuperVals)((ldef, gdef) => gdef.tpt.tpe = ldef.symbol.tpe) + val preSuperVals = treeInfo.preSuperFields(templ.body) + if (preSuperVals.isEmpty && preSuperStats.nonEmpty) + debugwarn("Wanted to zip empty presuper val list with " + preSuperStats) + else + map2(preSuperStats, preSuperVals)((ldef, gdef) => gdef.tpt.tpe = ldef.symbol.tpe) - case _ => - if (!supertparams.isEmpty) - MissingTypeArgumentsParentTpeError(supertpt) - } -/* experimental: early types as type arguments - val hasEarlyTypes = templ.body exists (treeInfo.isEarlyTypeDef) - val earlyMap = new EarlyMap(clazz) - List.mapConserve(supertpt :: mixins){ tpt => - val tpt1 = checkNoEscaping.privates(clazz, tpt) - if (hasEarlyTypes) tpt1 else tpt1 setType earlyMap(tpt1.tpe) + if (superCall1 == cunit) EmptyTree else cbody2 + case _ => + EmptyTree + } + + /** Makes sure that the first type tree in the list of parent types is always a class. + * If the first parent is a trait, prepend its supertype to the list until it's a class. + */ + private def normalizeFirstParent(parents: List[Tree]): List[Tree] = parents match { + case first :: rest if treeInfo.isTraitRef(first) => + def explode(supertpt: Tree, acc: List[Tree]): List[Tree] = { + if (treeInfo.isTraitRef(supertpt)) { + val supertpt1 = typedType(supertpt) + if (!supertpt1.isErrorTyped) { + val supersupertpt = TypeTree(supertpt1.tpe.firstParent) setPos supertpt.pos.focus + return explode(supersupertpt, supertpt1 :: acc) + } + } + if (supertpt.tpe.typeSymbol == AnyClass) supertpt.tpe = AnyRefClass.tpe + supertpt :: acc } -*/ + explode(first, Nil) ++ rest + case _ => parents + } - //Console.println("parents("+clazz") = "+supertpt :: mixins);//DEBUG + /** Certain parents are added in the parser before it is known whether + * that class also declared them as parents. For instance, this is an + * error unless we take corrective action here: + * + * case class Foo() extends Serializable + * + * So we strip the duplicates before typer. + */ + private def fixDuplicateSyntheticParents(parents: List[Tree]): List[Tree] = parents match { + case Nil => Nil + case x :: xs => + val sym = x.symbol + x :: fixDuplicateSyntheticParents( + if (isPossibleSyntheticParent(sym)) xs filterNot (_.symbol == sym) + else xs + ) + } - // Certain parents are added in the parser before it is known whether - // that class also declared them as parents. For instance, this is an - // error unless we take corrective action here: - // - // case class Foo() extends Serializable - // - // So we strip the duplicates before typer. - def fixDuplicates(remaining: List[Tree]): List[Tree] = remaining match { - case Nil => Nil - case x :: xs => - val sym = x.symbol - x :: fixDuplicates( - if (isPossibleSyntheticParent(sym)) xs filterNot (_.symbol == sym) - else xs - ) + def parentTypes(templ: Template): List[Tree] = templ.parents match { + case Nil => List(atPos(templ.pos)(TypeTree(AnyRefClass.tpe))) + case first :: rest => + try { + val supertpts = fixDuplicateSyntheticParents(normalizeFirstParent( + typedParentType(first, templ, inMixinPosition = false) +: + (rest map (typedParentType(_, templ, inMixinPosition = true))))) + + // if that is required to infer the targs of a super call + // typedParentType calls typedPrimaryConstrBody to do the inferring typecheck + // as a side effect, that typecheck also assigns types to the fields underlying early vals + // however if inference is not required, the typecheck doesn't happen + // and therefore early fields have their type trees not assigned + // here we detect this situation and take preventive measures + if (treeInfo.hasUntypedPreSuperFields(templ.body)) + typedPrimaryConstrBody(templ)(superRef => EmptyTree) + + supertpts mapConserve (tpt => checkNoEscaping.privates(context.owner, tpt)) + } catch { + case ex: TypeError => + // fallback in case of cyclic errors + // @H none of the tests enter here but I couldn't rule it out + // upd. @E when a definitions inherits itself, we end up here + // because `typedParentType` triggers `initialize` for parent types symbols + log("Type error calculating parents in template " + templ) + log("Error: " + ex) + ParentTypesError(templ, ex) + List(TypeTree(AnyRefClass.tpe)) } - - fixDuplicates(supertpt :: mixins) mapConserve (tpt => checkNoEscaping.privates(clazz, tpt)) - } - catch { - case ex: TypeError => - // fallback in case of cyclic errors - // @H none of the tests enter here but I couldn't rule it out - log("Type error calculating parents in template " + templ) - log("Error: " + ex) - ParentTypesError(templ, ex) - List(TypeTree(AnyRefClass.tpe)) - } + } /** <p>Check that</p> * <ul> @@ -1844,7 +1975,8 @@ trait Typers extends Modes with Adaptations with Tags { // the following is necessary for templates generated later assert(clazz.info.decls != EmptyScope, clazz) enterSyms(context.outer.make(templ, clazz, clazz.info.decls), templ.body) - validateParentClasses(parents1, selfType) + if (!templ.isErrorTyped) // if `parentTypes` has invalidated the template, don't validate it anymore + validateParentClasses(parents1, selfType) if (clazz.isCase) validateNoCaseAncestor(clazz) @@ -1854,9 +1986,28 @@ trait Typers extends Modes with Adaptations with Tags { if (!phase.erasedTypes && !clazz.info.resultType.isError) // @S: prevent crash for duplicated type members checkFinitary(clazz.info.resultType.asInstanceOf[ClassInfoType]) - val body = - if (isPastTyper || reporter.hasErrors) templ.body - else templ.body flatMap rewrappingWrapperTrees(namer.addDerivedTrees(Typer.this, _)) + val body = { + val body = + if (isPastTyper || reporter.hasErrors) templ.body + else templ.body flatMap rewrappingWrapperTrees(namer.addDerivedTrees(Typer.this, _)) + parents1.head match { + case CarriesSuperCallArgs(argss) => + if (clazz.isTrait) { + ConstrArgsInParentOfTraitError(parents1.head, clazz) + body + } else { + val primaryCtor = treeInfo.firstConstructor(templ.body) + val primaryCtor1 = (deriveDefDef(primaryCtor) { + case block @ Block(earlyVals :+ Apply(superRef, Nil), unit) => + val pos = wrappingPos(parents1.head.pos, argss.flatten) + val superCall = atPos(pos)((superRef /: argss)(Apply.apply)) + Block(earlyVals :+ superCall, unit) setPos pos + }) setPos pos + body map { case `primaryCtor` => primaryCtor1; case stat => stat } + } + case _ => body + } + } val body1 = typedStats(body, templ.symbol) @@ -2603,7 +2754,7 @@ trait Typers extends Modes with Adaptations with Tags { if (members.head eq EmptyTree) setError(tree) else { val typedBlock = typedPos(tree.pos, mode, pt) { - Block(ClassDef(anonClass, NoMods, ListOfNil, ListOfNil, members, tree.pos.focus), atPos(tree.pos.focus)(New(anonClass.tpe))) + Block(ClassDef(anonClass, NoMods, ListOfNil, members, tree.pos.focus), atPos(tree.pos.focus)(New(anonClass.tpe))) } // Don't leak implementation details into the type, see SI-6575 if (isPartial && !typedBlock.isErrorTyped) |