diff options
Diffstat (limited to 'src/compiler/scala/tools/nsc/typechecker/Typers.scala')
| -rw-r--r-- | src/compiler/scala/tools/nsc/typechecker/Typers.scala | 683 |
1 files changed, 333 insertions, 350 deletions
diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala index 16d3f5134b..fdf7058ab1 100644 --- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala +++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala @@ -158,7 +158,9 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper for(ar <- argResultsBuff) paramTp = paramTp.subst(ar.subst.from, ar.subst.to) - val res = if (paramFailed || (paramTp.isErroneous && {paramFailed = true; true})) SearchFailure else inferImplicit(fun, paramTp, context.reportErrors, isView = false, context) + val res = + if (paramFailed || (paramTp.isErroneous && {paramFailed = true; true})) SearchFailure + else inferImplicitFor(paramTp, fun, context, reportAmbiguous = context.reportErrors) argResultsBuff += res if (res.isSuccess) { @@ -194,14 +196,12 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper !from.isError && !to.isError && context.implicitsEnabled - && (inferView(context.tree, from, to, reportAmbiguous = false, saveErrors = true) != EmptyTree) + && (inferView(context.tree, from, to, reportAmbiguous = false) != EmptyTree) // SI-8230 / SI-8463 We'd like to change this to `saveErrors = false`, but can't. // For now, we can at least pass in `context.tree` rather then `EmptyTree` so as // to avoid unpositioned type errors. ) - def inferView(tree: Tree, from: Type, to: Type, reportAmbiguous: Boolean): Tree = - inferView(tree, from, to, reportAmbiguous, saveErrors = true) /** Infer an implicit conversion (`view`) between two types. * @param tree The tree which needs to be converted. @@ -214,25 +214,23 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper * during the inference of a view be put into the original buffer. * False iff we don't care about them. */ - def inferView(tree: Tree, from: Type, to: Type, reportAmbiguous: Boolean, saveErrors: Boolean): Tree = { - debuglog("infer view from "+from+" to "+to)//debug - if (isPastTyper) EmptyTree - else from match { - case MethodType(_, _) => EmptyTree - case OverloadedType(_, _) => EmptyTree - case PolyType(_, _) => EmptyTree - case _ => - def wrapImplicit(from: Type): Tree = { - val result = inferImplicit(tree, functionType(from.withoutAnnotations :: Nil, to), reportAmbiguous, isView = true, context, saveAmbiguousDivergent = saveErrors) - if (result.subst != EmptyTreeTypeSubstituter) { - result.subst traverse tree - notifyUndetparamsInferred(result.subst.from, result.subst.to) - } - result.tree - } - wrapImplicit(from) orElse wrapImplicit(byNameType(from)) + def inferView(tree: Tree, from: Type, to: Type, reportAmbiguous: Boolean = true, saveErrors: Boolean = true): Tree = + if (isPastTyper || from.isInstanceOf[MethodType] || from.isInstanceOf[OverloadedType] || from.isInstanceOf[PolyType]) EmptyTree + else { + debuglog(s"Inferring view from $from to $to for $tree (reportAmbiguous= $reportAmbiguous, saveErrors=$saveErrors)") + + val fromNoAnnot = from.withoutAnnotations + val result = inferImplicitView(fromNoAnnot, to, tree, context, reportAmbiguous, saveErrors) match { + case fail if fail.isFailure => inferImplicitView(byNameType(fromNoAnnot), to, tree, context, reportAmbiguous, saveErrors) + case ok => ok + } + + if (result.subst != EmptyTreeTypeSubstituter) { + result.subst traverse tree + notifyUndetparamsInferred(result.subst.from, result.subst.to) + } + result.tree } - } import infer._ @@ -246,6 +244,10 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper var context = context0 def context1 = context + // for use with silent type checking to when we can't have results with undetermined type params + // note that this captures the context var + val isMonoContext = (_: Any) => context.undetparams.isEmpty + def dropExistential(tp: Type): Type = tp match { case ExistentialType(tparams, tpe) => new SubstWildcardMap(tparams).apply(tp) @@ -732,7 +734,7 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper featureTrait.owner.ownerChain.takeWhile(_ != languageFeatureModule.moduleClass).reverse val featureName = (nestedOwners map (_.name + ".")).mkString + featureTrait.name def action(): Boolean = { - def hasImport = inferImplicit(EmptyTree: Tree, featureTrait.tpe, reportAmbiguous = true, isView = false, context).isSuccess + def hasImport = inferImplicitByType(featureTrait.tpe, context).isSuccess def hasOption = settings.language contains featureName val OK = hasImport || hasOption if (!OK) { @@ -809,7 +811,8 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper * (11) Widen numeric literals to their expected type, if necessary * (12) When in mode EXPRmode, convert E to { E; () } if expected type is scala.Unit. * (13) When in mode EXPRmode, apply AnnotationChecker conversion if expected type is annotated. - * (14) When in mode EXPRmode, apply a view + * (14) When in mode EXPRmode, do SAM conversion + * (15) When in mode EXPRmode, apply a view * If all this fails, error */ protected def adapt(tree: Tree, mode: Mode, pt: Type, original: Tree = EmptyTree): Tree = { @@ -1021,72 +1024,70 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper } } - def fallbackAfterVanillaAdapt(): Tree = { - def isPopulatedPattern = { - if ((tree.symbol ne null) && tree.symbol.isModule) - inferModulePattern(tree, pt) - - isPopulated(tree.tpe, approximateAbstracts(pt)) + def adaptExprNotFunMode(): Tree = { + def lastTry(err: AbsTypeError = null): Tree = { + debuglog("error tree = " + tree) + if (settings.debug && settings.explaintypes) explainTypes(tree.tpe, pt) + if (err ne null) context.issue(err) + if (tree.tpe.isErroneous || pt.isErroneous) setError(tree) + else adaptMismatchedSkolems() } - if (mode.inPatternMode && isPopulatedPattern) - return tree - val tree1 = constfold(tree, pt) // (10) (11) - if (tree1.tpe <:< pt) - return adapt(tree1, mode, pt, original) + // TODO: should we even get to fallbackAfterVanillaAdapt for an ill-typed tree? + if (mode.typingExprNotFun && !tree.tpe.isErroneous) { + @inline def tpdPos(transformed: Tree) = typedPos(tree.pos, mode, pt)(transformed) + @inline def tpd(transformed: Tree) = typed(transformed, mode, pt) - if (mode.typingExprNotFun) { - // The <: Any requirement inhibits attempts to adapt continuation types - // to non-continuation types. - if (tree.tpe <:< AnyTpe) pt.dealias match { - case TypeRef(_, UnitClass, _) => // (12) - if (!isPastTyper && settings.warnValueDiscard) - context.warning(tree.pos, "discarded non-Unit value") - return typedPos(tree.pos, mode, pt)(Block(List(tree), Literal(Constant(())))) - case TypeRef(_, sym, _) if isNumericValueClass(sym) && isNumericSubType(tree.tpe, pt) => - if (!isPastTyper && settings.warnNumericWiden) - context.warning(tree.pos, "implicit numeric widening") - return typedPos(tree.pos, mode, pt)(Select(tree, "to" + sym.name)) - case _ => - } - if (pt.dealias.annotations.nonEmpty && canAdaptAnnotations(tree, this, mode, pt)) // (13) - return typed(adaptAnnotations(tree, this, mode, pt), mode, pt) + @inline def warnValueDiscard(): Unit = + if (!isPastTyper && settings.warnValueDiscard) context.warning(tree.pos, "discarded non-Unit value") + @inline def warnNumericWiden(): Unit = + if (!isPastTyper && settings.warnNumericWiden) context.warning(tree.pos, "implicit numeric widening") - if (hasUndets) - return instantiate(tree, mode, pt) - - if (context.implicitsEnabled && !pt.isError && !tree.isErrorTyped) { - // (14); the condition prevents chains of views - debuglog("inferring view from " + tree.tpe + " to " + pt) - inferView(tree, tree.tpe, pt, reportAmbiguous = true) match { - case EmptyTree => - case coercion => - def msg = "inferred view from " + tree.tpe + " to " + pt + " = " + coercion + ":" + coercion.tpe - if (settings.logImplicitConv) - context.echo(tree.pos, msg) - - debuglog(msg) - val silentContext = context.makeImplicit(context.ambiguousErrors) - val res = newTyper(silentContext).typed( - new ApplyImplicitView(coercion, List(tree)) setPos tree.pos, mode, pt) - silentContext.reporter.firstError match { - case Some(err) => context.issue(err) - case None => return res + // The <: Any requirement inhibits attempts to adapt continuation types to non-continuation types. + val anyTyped = tree.tpe <:< AnyTpe + + pt.dealias match { + case TypeRef(_, UnitClass, _) if anyTyped => // (12) + warnValueDiscard() ; tpdPos(gen.mkUnitBlock(tree)) + case TypeRef(_, numValueCls, _) if anyTyped && isNumericValueClass(numValueCls) && isNumericSubType(tree.tpe, pt) => // (10) (11) + warnNumericWiden() ; tpdPos(Select(tree, s"to${numValueCls.name}")) + case dealiased if dealiased.annotations.nonEmpty && canAdaptAnnotations(tree, this, mode, pt) => // (13) + tpd(adaptAnnotations(tree, this, mode, pt)) + case _ => + if (hasUndets) instantiate(tree, mode, pt) + else { + // (14) sam conversion + // TODO: figure out how to avoid partially duplicating typedFunction (samMatchingFunction) + // Could we infer the SAM type, assign it to the tree and add the attachment, + // all in one fell swoop at the end of typedFunction? + val samAttach = inferSamType(tree, pt, mode) + + if (samAttach.samTp ne NoType) tree.setType(samAttach.samTp).updateAttachment(samAttach) + else { // (15) implicit view application + val coercion = + if (context.implicitsEnabled) inferView(tree, tree.tpe, pt) + else EmptyTree + if (coercion ne EmptyTree) { + def msg = s"inferred view from ${tree.tpe} to $pt via $coercion: ${coercion.tpe}" + if (settings.logImplicitConv) context.echo(tree.pos, msg) + else debuglog(msg) + + val viewApplied = new ApplyImplicitView(coercion, List(tree)) setPos tree.pos + val silentContext = context.makeImplicit(context.ambiguousErrors) + val typedView = newTyper(silentContext).typed(viewApplied, mode, pt) + + silentContext.reporter.firstError match { + case None => typedView + case Some(err) => lastTry(err) + } + } else lastTry() } - } + } } - } - - debuglog("error tree = " + tree) - if (settings.debug && settings.explaintypes) - explainTypes(tree.tpe, pt) - - if (tree.tpe.isErroneous || pt.isErroneous) - setError(tree) - else - adaptMismatchedSkolems() + } else lastTry() } + def vanillaAdapt(tree: Tree) = { def applyPossible = { def applyMeth = member(adaptToName(tree, nme.apply), nme.apply) @@ -1120,8 +1121,13 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper } else if (tree.tpe <:< pt) tree - else - fallbackAfterVanillaAdapt() + else if (mode.inPatternMode && { inferModulePattern(tree, pt); isPopulated(tree.tpe, approximateAbstracts(pt)) }) + tree + else { + val constFolded = constfold(tree, pt) + if (constFolded.tpe <:< pt) adapt(constFolded, mode, pt, original) // set stage for (0) + else adaptExprNotFunMode() // (10) -- (15) + } } // begin adapt @@ -1186,7 +1192,7 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper val savedUndetparams = context.undetparams silent(_.instantiate(tree, mode, UnitTpe)) orElse { _ => context.undetparams = savedUndetparams - val valueDiscard = atPos(tree.pos)(Block(List(instantiate(tree, mode, WildcardType)), Literal(Constant(())))) + val valueDiscard = atPos(tree.pos)(gen.mkUnitBlock(instantiate(tree, mode, WildcardType))) typed(valueDiscard, mode, UnitTpe) } } @@ -1247,7 +1253,7 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper * If no conversion is found, return `qual` unchanged. * */ - def adaptToArguments(qual: Tree, name: Name, args: List[Tree], pt: Type, reportAmbiguous: Boolean, saveErrors: Boolean): Tree = { + def adaptToArguments(qual: Tree, name: Name, args: List[Tree], pt: Type, reportAmbiguous: Boolean = true, saveErrors: Boolean = true): Tree = { def doAdapt(restpe: Type) = //util.trace("adaptToArgs "+qual+", name = "+name+", argtpes = "+(args map (_.tpe))+", pt = "+pt+" = ") adaptToMember(qual, HasMethodMatching(name, args map (_.tpe), restpe), reportAmbiguous, saveErrors) @@ -1263,7 +1269,7 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper * a method `name`. If that's ambiguous try taking arguments into * account using `adaptToArguments`. */ - def adaptToMemberWithArgs(tree: Tree, qual: Tree, name: Name, mode: Mode, reportAmbiguous: Boolean, saveErrors: Boolean): Tree = { + def adaptToMemberWithArgs(tree: Tree, qual: Tree, name: Name, mode: Mode, reportAmbiguous: Boolean = true, saveErrors: Boolean = true): Tree = { def onError(reportError: => Tree): Tree = context.tree match { case Apply(tree1, args) if (tree1 eq tree) && args.nonEmpty => ( silent (_.typedArgs(args.map(_.duplicate), mode)) @@ -1745,17 +1751,21 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper classinfo.parents map (_.instantiateTypeParams(List(tparam), List(AnyRefTpe))), classinfo.decls, clazz) - clazz.setInfo { - clazz.info match { - case PolyType(tparams, _) => PolyType(tparams, newinfo) - case _ => newinfo - } - } + updatePolyClassInfo(clazz, newinfo) FinitaryError(tparam) } } } + private def updatePolyClassInfo(clazz: Symbol, newinfo: ClassInfoType): clazz.type = { + clazz.setInfo { + clazz.info match { + case PolyType(tparams, _) => PolyType(tparams, newinfo) + case _ => newinfo + } + } + } + def typedClassDef(cdef: ClassDef): Tree = { val clazz = cdef.symbol val typedMods = typedModifiers(cdef.mods) @@ -1864,6 +1874,26 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper // please FIXME: uncommenting this line breaks everything // val templ = treeCopy.Template(templ0, templ0.body, templ0.self, templ0.parents) val clazz = context.owner + + val parentTypes = parents1.map(_.tpe) + + // The parents may have been normalized by typedParentTypes. + // We must update the info as well, or we won't find the super constructor for our now-first parent class + // Consider `class C ; trait T extends C ; trait U extends T` + // `U`'s info will start with parent `T`, but `typedParentTypes` will return `List(C, T)` (`== parents1`) + // now, the super call in the primary ctor will fail to find `C`'s ctor, since it bases its search on + // `U`'s info, not the trees. + // + // For correctness and performance, we restrict this rewrite to anonymous classes, + // as others have their parents in order already (it seems!), and we certainly + // don't want to accidentally rewire superclasses for e.g. the primitive value classes. + // + // TODO: Find an example of a named class needing this rewrite, I tried but couldn't find one. + if (clazz.isAnonymousClass && clazz.info.parents != parentTypes) { +// println(s"updating parents of $clazz from ${clazz.info.parents} to $parentTypes") + updatePolyClassInfo(clazz, ClassInfoType(parentTypes, clazz.info.decls, clazz)) + } + clazz.annotations.map(_.completeInfo()) if (templ.symbol == NoSymbol) templ setSymbol clazz.newLocalDummy(templ.pos) @@ -2713,187 +2743,99 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper } } - /** Synthesize and type check the implementation of a type with a Single Abstract Method - * - * `{ (p1: T1, ..., pN: TN) => body } : S` - * - * expands to (where `S` is the expected type that defines a single abstract method named `apply`) - * - * `{ - * def apply$body(p1: T1, ..., pN: TN): T = body - * new S { - * def apply(p1: T1', ..., pN: TN'): T' = apply$body(p1,..., pN) - * } - * }` - * - * If 'T' is not fully defined, it is inferred by type checking - * `apply$body` without a result type before type checking the block. - * The method's inferred result type is used instead of `T`. [See test/files/pos/sammy_poly.scala] - * - * The `apply` method is identified by the argument `sam`; `S` corresponds to the argument `samClassTp`, - * and `resPt` is derived from `samClassTp` -- it may be fully defined, or not... - * If it is not fully defined, we derive `samClassTpFullyDefined` by inferring any unknown type parameters. - * - * The types T1' ... TN' and T' are derived from the method signature of the sam method, - * as seen from the fully defined `samClassTpFullyDefined`. - * - * The function's body is put in a method outside of the class definition to enforce scoping. - * S's members should not be in scope in `body`. - * - * The restriction on implicit arguments (neither S's constructor, nor sam may take an implicit argument list), - * is largely to keep the implementation of type inference (the computation of `samClassTpFullyDefined`) simple. - * - * NOTE: it would be nicer to not have to type check `apply$body` separately when `T` is not fully defined. - * However T must be fully defined before we type the instantiation, as it'll end up as a parent type, - * which must be fully defined. Would be nice to have some kind of mechanism to insert type vars in a block of code, - * and have the instantiation of the first occurrence propagate to the rest of the block. - * - * TODO: by-name params - * scala> trait LazySink { def accept(a: => Any): Unit } - * defined trait LazySink - * - * scala> val f: LazySink = (a) => (a, a) - * f: LazySink = $anonfun$1@1fb26910 - * - * scala> f(println("!")) - * <console>:10: error: LazySink does not take parameters - * f(println("!")) - * ^ - * - * scala> f.accept(println("!")) - * ! - * ! - */ - def synthesizeSAMFunction(sam: Symbol, fun: Function, resPt: Type, samClassTp: Type, mode: Mode): Tree = { - // assert(fun.vparams forall (vp => isFullyDefined(vp.tpt.tpe))) -- by construction, as we take them from sam's info - val sampos = fun.pos - - // if the expected sam type is fully defined, use it for the method's result type - // otherwise, NoType, so that type inference will determine the method's result type - // resPt is syntactically contained in samClassTp, so if the latter is fully defined, so is the former - // ultimately, we want to fully define samClassTp as it is used as the superclass of our anonymous class - val samDefTp = if (isFullyDefined(resPt)) resPt else NoType - val bodyName = newTermName(sam.name + "$body") - - // `def '${sam.name}\$body'($p1: $T1, ..., $pN: $TN): $resPt = $body` - val samBodyDef = - DefDef(NoMods, - bodyName, - Nil, - List(fun.vparams.map(_.duplicate)), // must duplicate as we're also using them for `samDef` - TypeTree(samDefTp) setPos sampos.focus, - fun.body) - - // If we need to enter the sym for the body def before type checking the block, - // we'll create a nested context, as explained below. - var nestedTyper = this - - // Type check body def before classdef to fully determine samClassTp (if necessary). - // As `samClassTp` determines a parent type for the class, - // we can't type check `block` in one go unless `samClassTp` is fully defined. - val samClassTpFullyDefined = - if (isFullyDefined(samClassTp)) samClassTp + /** Synthesize and type check the implementation of a type with a Single Abstract Method. + * + * Based on a type checked Function node `{ (p1: T1, ..., pN: TN) => body } : S` + * where `S` is the expected type that defines a single abstract method (call it `apply` for the example), + * that has signature `(p1: T1', ..., pN: TN'): T'`, synthesize the instantiation of the following anonymous class + * + * ``` + * new S { + * def apply$body(p1: T1, ..., pN: TN): T = body + * def apply(p1: T1', ..., pN: TN'): T' = apply$body(p1,..., pN) + * } + * ``` + * + * The `apply` method is identified by the argument `sam`; `S` corresponds to the argument `pt`, + * If `pt` is not fully defined, we derive `samClassTpFullyDefined` by inferring any unknown type parameters. + * + * The types T1' ... TN' and T' are derived from the method signature of the sam method, + * as seen from the fully defined `samClassTpFullyDefined`. + * + * The function's body is put in a (static) method in the class definition to enforce scoping. + * S's members should not be in scope in `body`. (Putting it in the block outside the class runs into implementation problems described below) + * + * The restriction on implicit arguments (neither S's constructor, nor sam may take an implicit argument list), + * is to keep the implementation of type inference (the computation of `samClassTpFullyDefined`) simple. + * + * Impl notes: + * - `fun` has a FunctionType, but the expected type `pt` is some SAM type -- let's remedy that + * - `fun` is fully attributed, so we'll have to wrangle some symbols into shape (owner change, vparam syms) + * - after experimentation, it works best to type check function literals fully first and then adapt to a sam type, + * as opposed to a sam-specific code paths earlier on in type checking (in typedFunction). + * For one, we want to emit the same bytecode regardless of whether the expected + * function type is a built-in FunctionN or some SAM type + * + */ + def inferSamType(fun: Tree, pt: Type, mode: Mode): SAMFunction = { + val sam = + if (fun.isInstanceOf[Function] && !isFunctionType(pt)) { + // TODO: can we ensure there's always a SAMFunction attachment, instead of looking up the sam again??? + // seems like overloading complicates things? + val sam = samOf(pt) + if (samMatchesFunctionBasedOnArity(sam, fun.asInstanceOf[Function].vparams)) sam + else NoSymbol + } else NoSymbol + + def fullyDefinedMeetsExpectedFunTp(pt: Type): Boolean = isFullyDefined(pt) && { + val samMethType = pt memberInfo sam + fun.tpe <:< functionType(samMethType.paramTypes, samMethType.resultType) + } + + SAMFunction( + if (!sam.exists) NoType + else if (fullyDefinedMeetsExpectedFunTp(pt)) pt else try { - // This creates a symbol for samBodyDef with a type completer that'll be triggered immediately below. - // The symbol is entered in the same scope used for the block below, and won't thus be reentered later. - // It has to be a new scope, though, or we'll "get ambiguous reference to overloaded definition" [pos/sammy_twice.scala] - // makeSilent: [pos/nonlocal-unchecked.scala -- when translation all functions to sams] - val nestedCtx = enterSym(context.makeNewScope(context.tree, context.owner).makeSilent(), samBodyDef) - nestedTyper = newTyper(nestedCtx) - - // NOTE: this `samBodyDef.symbol.info` runs the type completer set up by the enterSym above - val actualSamType = samBodyDef.symbol.info + val samClassSym = pt.typeSymbol // we're trying to fully define the type arguments for this type constructor - val samTyCon = samClassTp.typeSymbol.typeConstructor + val samTyCon = samClassSym.typeConstructor // the unknowns - val tparams = samClassTp.typeSymbol.typeParams + val tparams = samClassSym.typeParams // ... as typevars - val tvars = tparams map freshVar - - // 1. Recover partial information: - // - derive a type from samClassTp that has the corresponding tparams for type arguments that aren't fully defined - // - constrain typevars to be equal to type args that are fully defined - val samClassTpMoreDefined = appliedType(samTyCon, - (samClassTp.typeArgs, tparams, tvars).zipped map { - case (a, _, tv) if isFullyDefined(a) => tv =:= a; a - case (_, p, _) => p.typeConstructor - }) - - // the method type we're expecting the synthesized sam to have, based on the expected sam type, - // where fully defined type args to samClassTp have been preserved, - // with the unknown args replaced by their corresponding type param - val expectedSamType = samClassTpMoreDefined.memberInfo(sam) + val tvars = tparams map freshVar - // 2. make sure the body def's actual type (formals and result) conforms to - // sam's expected type (in terms of the typevars that represent the sam's class's type params) - actualSamType <:< expectedSamType.substituteTypes(tparams, tvars) + val ptVars = appliedType(samTyCon, tvars) - // solve constraints tracked by tvars - val targs = solvedTypes(tvars, tparams, tparams map varianceInType(sam.info), upper = false, lubDepth(sam.info :: Nil)) + // carry over info from pt + ptVars <:< pt - debuglog(s"sam infer: $samClassTp --> ${appliedType(samTyCon, targs)} by $actualSamType <:< $expectedSamType --> $targs for $tparams") + val samInfoWithTVars = ptVars.memberInfo(sam) - // a fully defined samClassTp - appliedType(samTyCon, targs) - } catch { - case _: NoInstance | _: TypeError => - devWarning(sampos, s"Could not define type $samClassTp using ${samBodyDef.symbol.rawInfo} <:< ${samClassTp memberInfo sam} (for $sam)") - samClassTp - } - - // what's the signature of the method that we should actually be overriding? - val samMethTp = samClassTpFullyDefined memberInfo sam - // Before the mutation, `tp <:< vpar.tpt.tpe` should hold. - // TODO: error message when this is not the case, as the expansion won't type check - // - Ti' <:< Ti and T <: T' must hold for the samDef body to type check - val funArgTps = foreach2(samMethTp.paramTypes, fun.vparams)((tp, vpar) => vpar.tpt setType tp) - - // `final override def ${sam.name}($p1: $T1', ..., $pN: $TN'): ${samMethTp.finalResultType} = ${sam.name}\$body'($p1, ..., $pN)` - val samDef = - DefDef(Modifiers(FINAL | OVERRIDE | SYNTHETIC), - sam.name.toTermName, - Nil, - List(fun.vparams), - TypeTree(samMethTp.finalResultType) setPos sampos.focus, - Apply(Ident(bodyName), fun.vparams map gen.paramToArg) - ) + // use function type subtyping, not method type subtyping (the latter is invariant in argument types) + fun.tpe <:< functionType(samInfoWithTVars.paramTypes, samInfoWithTVars.finalResultType) - val serializableParentAddendum = - if (typeIsSubTypeOfSerializable(samClassTp)) Nil - else List(TypeTree(SerializableTpe)) - - val classDef = - ClassDef(Modifiers(FINAL), tpnme.ANON_FUN_NAME, tparams = Nil, - gen.mkTemplate( - parents = TypeTree(samClassTpFullyDefined) :: serializableParentAddendum, - self = noSelfType, - constrMods = NoMods, - vparamss = ListOfNil, - body = List(samDef), - superPos = sampos.focus - ) - ) + val variances = tparams map varianceInType(sam.info) - // type checking the whole block, so that everything is packaged together nicely - // and we don't have to create any symbols by hand - val block = - nestedTyper.typedPos(sampos, mode, samClassTpFullyDefined) { - Block( - samBodyDef, - classDef, - Apply(Select(New(Ident(tpnme.ANON_FUN_NAME)), nme.CONSTRUCTOR), Nil) - ) - } + // solve constraints tracked by tvars + val targs = solvedTypes(tvars, tparams, variances, upper = false, lubDepth(sam.info :: Nil)) - // TODO: improve error reporting -- when we're in silent mode (from `silent(_.doTypedApply(tree, fun, args, mode, pt)) orElse onError`) - // the errors in the function don't get out... - if (block exists (_.isErroneous)) - context.error(fun.pos, s"Could not derive subclass of $samClassTp\n (with SAM `def $sam$samMethTp`)\n based on: $fun.") + debuglog(s"sam infer: $pt --> ${appliedType(samTyCon, targs)} by ${fun.tpe} <:< $samInfoWithTVars --> $targs for $tparams") - classDef.symbol addAnnotation SerialVersionUIDAnnotation - block + val ptFullyDefined = appliedType(samTyCon, targs) + if (ptFullyDefined <:< pt && fullyDefinedMeetsExpectedFunTp(ptFullyDefined)) { + debuglog(s"sam fully defined expected type: $ptFullyDefined from $pt for ${fun.tpe}") + ptFullyDefined + } else { + debuglog(s"Could not define type $pt using ${fun.tpe} <:< ${pt memberInfo sam} (for $sam)") + NoType + } + } catch { + case e@(_: NoInstance | _: TypeError) => + debuglog(s"Error during SAM synthesis: could not define type $pt using ${fun.tpe} <:< ${pt memberInfo sam} (for $sam)\n$e") + NoType + }, sam) } /** Type check a function literal. @@ -2903,16 +2845,19 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper * - a type with a Single Abstract Method (under -Xexperimental for now). */ private def typedFunction(fun: Function, mode: Mode, pt: Type): Tree = { - val numVparams = fun.vparams.length + val vparams = fun.vparams + val numVparams = vparams.length val FunctionSymbol = if (numVparams > definitions.MaxFunctionArity) NoSymbol else FunctionClass(numVparams) + val ptSym = pt.typeSymbol + /* The Single Abstract Member of pt, unless pt is the built-in function type of the expected arity, * as `(a => a): Int => Int` should not (yet) get the sam treatment. */ val sam = - if (pt.typeSymbol == FunctionSymbol) NoSymbol + if (ptSym == NoSymbol || ptSym == FunctionSymbol || ptSym == PartialFunctionClass) NoSymbol else samOf(pt) /* The SAM case comes first so that this works: @@ -2920,79 +2865,101 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper * (a => a): MyFun * * Note that the arity of the sam must correspond to the arity of the function. + * TODO: handle vararg sams? */ - val samViable = sam.exists && sameLength(sam.info.params, fun.vparams) - val ptNorm = if (samViable) samToFunctionType(pt, sam) else pt + val ptNorm = + if (samMatchesFunctionBasedOnArity(sam, vparams)) samToFunctionType(pt, sam) + else pt val (argpts, respt) = ptNorm baseType FunctionSymbol match { case TypeRef(_, FunctionSymbol, args :+ res) => (args, res) - case _ => (fun.vparams map (_ => if (pt == ErrorType) ErrorType else NoType), WildcardType) + case _ => (vparams map (if (pt == ErrorType) (_ => ErrorType) else (_ => NoType)), WildcardType) } - if (!FunctionSymbol.exists) - MaxFunctionArityError(fun) - else if (argpts.lengthCompare(numVparams) != 0) - WrongNumberOfParametersError(fun, argpts) + if (!FunctionSymbol.exists) MaxFunctionArityError(fun) + else if (argpts.lengthCompare(numVparams) != 0) WrongNumberOfParametersError(fun, argpts) else { - var issuedMissingParameterTypeError = false - foreach2(fun.vparams, argpts) { (vparam, argpt) => - if (vparam.tpt.isEmpty) { - val vparamType = - if (isFullyDefined(argpt)) argpt - else { - fun match { - case etaExpansion(vparams, fn, args) => - silent(_.typed(fn, mode.forFunMode, pt)) filter (_ => context.undetparams.isEmpty) map { fn1 => - // if context.undetparams is not empty, the function was polymorphic, - // so we need the missing arguments to infer its type. See #871 - //println("typing eta "+fun+":"+fn1.tpe+"/"+context.undetparams) - val ftpe = normalize(fn1.tpe) baseType FunctionClass(numVparams) - if (isFunctionType(ftpe) && isFullyDefined(ftpe)) - return typedFunction(fun, mode, ftpe) - } - case _ => - } - MissingParameterTypeError(fun, vparam, pt, withTupleAddendum = !issuedMissingParameterTypeError) - issuedMissingParameterTypeError = true - ErrorType - } - vparam.tpt.setType(vparamType) + val paramsMissingType = mutable.ArrayBuffer.empty[ValDef] //.sizeHint(numVparams) probably useless, since initial size is 16 and max fun arity is 22 + // first, try to define param types from expected function's arg types if needed + foreach2(vparams, argpts) { (vparam, argpt) => + if (vparam.tpt isEmpty) { + if (isFullyDefined(argpt)) vparam.tpt setType argpt + else paramsMissingType += vparam + if (!vparam.tpt.pos.isDefined) vparam.tpt setPos vparam.pos.focus } } - fun.body match { - // translate `x => x match { <cases> }` : PartialFunction to - // `new PartialFunction { def applyOrElse(x, default) = x match { <cases> } def isDefinedAt(x) = ... }` - case Match(sel, cases) if (sel ne EmptyTree) && (pt.typeSymbol == PartialFunctionClass) => - // go to outer context -- must discard the context that was created for the Function since we're discarding the function - // thus, its symbol, which serves as the current context.owner, is not the right owner - // you won't know you're using the wrong owner until lambda lift crashes (unless you know better than to use the wrong owner) - val outerTyper = newTyper(context.outer) - val p = fun.vparams.head - if (p.tpt.tpe == null) p.tpt setType outerTyper.typedType(p.tpt).tpe + // If we're typing `(a1: T1, ..., aN: TN) => m(a1,..., aN)`, where some Ti are not fully defined, + // type `m` directly (undoing eta-expansion of method m) to determine the argument types. + // This tree is the result from one of: + // - manual eta-expansion with named arguments (x => f(x)); + // - wildcard-style eta expansion (`m(_, _,)`); + // - instantiateToMethodType adapting a tree of method type to a function type using etaExpand. + // + // Note that method values are a separate thing (`m _`): they have the idiosyncratic shape + // of `Typed(expr, Function(Nil, EmptyTree))` + val ptUnrollingEtaExpansion = + if (paramsMissingType.nonEmpty && pt != ErrorType) fun.body match { + // we can compare arguments and parameters by name because there cannot be a binder between + // the function's valdefs and the Apply's arguments + case Apply(meth, args) if (vparams corresponds args) { case (p, Ident(name)) => p.name == name case _ => false } => + // We're looking for a method (as indicated by FUNmode in the silent typed below), + // so let's make sure our expected type is a MethodType + val methArgs = NoSymbol.newSyntheticValueParams(argpts map { case NoType => WildcardType case tp => tp }) + silent(_.typed(meth, mode.forFunMode, MethodType(methArgs, respt))) filter (isMonoContext) map { methTyped => + // if context.undetparams is not empty, the method was polymorphic, + // so we need the missing arguments to infer its type. See #871 + val funPt = normalize(methTyped.tpe) baseType FunctionClass(numVparams) + // println(s"typeUnEtaExpanded $meth : ${methTyped.tpe} --> normalized: $funPt") + + // If we are sure this function type provides all the necesarry info, so that we won't have + // any undetermined argument types, go ahead an recurse below (`typedFunction(fun, mode, ptUnrollingEtaExpansion)`) + // and rest assured we won't end up right back here (and keep recursing) + if (isFunctionType(funPt) && funPt.typeArgs.iterator.take(numVparams).forall(isFullyDefined)) funPt + else null + } orElse { _ => null } + case _ => null + } else null + + + if (ptUnrollingEtaExpansion ne null) typedFunction(fun, mode, ptUnrollingEtaExpansion) + else { + // we ran out of things to try, missing parameter types are an irrevocable error + var issuedMissingParameterTypeError = false + paramsMissingType.foreach { vparam => + vparam.tpt setType ErrorType + MissingParameterTypeError(fun, vparam, pt, withTupleAddendum = !issuedMissingParameterTypeError) + issuedMissingParameterTypeError = true + } - outerTyper.synthesizePartialFunction(p.name, p.pos, paramSynthetic = false, fun.body, mode, pt) + fun.body match { + // translate `x => x match { <cases> }` : PartialFunction to + // `new PartialFunction { def applyOrElse(x, default) = x match { <cases> } def isDefinedAt(x) = ... }` + case Match(sel, cases) if (sel ne EmptyTree) && (pt.typeSymbol == PartialFunctionClass) => + // go to outer context -- must discard the context that was created for the Function since we're discarding the function + // thus, its symbol, which serves as the current context.owner, is not the right owner + // you won't know you're using the wrong owner until lambda lift crashes (unless you know better than to use the wrong owner) + val outerTyper = newTyper(context.outer) + val p = vparams.head + if (p.tpt.tpe == null) p.tpt setType outerTyper.typedType(p.tpt).tpe - // Use synthesizeSAMFunction to expand `(p1: T1, ..., pN: TN) => body` - // to an instance of the corresponding anonymous subclass of `pt`. - case _ if samViable => - newTyper(context.outer).synthesizeSAMFunction(sam, fun, respt, pt, mode) + outerTyper.synthesizePartialFunction(p.name, p.pos, paramSynthetic = false, fun.body, mode, pt) - // regular Function - case _ => - val vparamSyms = fun.vparams map { vparam => - enterSym(context, vparam) - if (context.retyping) context.scope enter vparam.symbol - vparam.symbol - } - val vparams = fun.vparams mapConserve typedValDef - val formals = vparamSyms map (_.tpe) - val body1 = typed(fun.body, respt) - val restpe = packedType(body1, fun.symbol).deconst.resultType - val funtpe = phasedAppliedType(FunctionSymbol, formals :+ restpe) + case _ => + val vparamSyms = vparams map { vparam => + enterSym(context, vparam) + if (context.retyping) context.scope enter vparam.symbol + vparam.symbol + } + val vparamsTyped = vparams mapConserve typedValDef + val formals = vparamSyms map (_.tpe) + val body1 = typed(fun.body, respt) + val restpe = packedType(body1, fun.symbol).deconst.resultType + val funtpe = phasedAppliedType(FunctionSymbol, formals :+ restpe) - treeCopy.Function(fun, vparams, body1) setType funtpe + treeCopy.Function(fun, vparamsTyped, body1) setType funtpe + } } } } @@ -3222,7 +3189,10 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper // less expensive than including them in inferMethodAlternative (see below). def shapeType(arg: Tree): Type = arg match { case Function(vparams, body) => - functionType(vparams map (_ => AnyTpe), shapeType(body)) // TODO: should this be erased when retyping during erasure? + // No need for phasedAppliedType, as we don't get here during erasure -- + // overloading resolution happens during type checking. + // During erasure, the condition above (fun.symbol.isOverloaded) is false. + functionType(vparams map (_ => AnyTpe), shapeType(body)) case AssignOrNamedArg(Ident(name), rhs) => NamedType(name, shapeType(rhs)) case _ => @@ -4303,7 +4273,8 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper if (pt.typeSymbol == PartialFunctionClass) synthesizePartialFunction(newTermName(context.unit.fresh.newName("x")), tree.pos, paramSynthetic = true, tree, mode, pt) else { - val arity = if (isFunctionType(pt)) pt.dealiasWiden.typeArgs.length - 1 else 1 + val arity = functionArityFromType(pt) match { case -1 => 1 case arity => arity } // SI-8429: consider sam and function type equally in determining function arity + val params = for (i <- List.range(0, arity)) yield atPos(tree.pos.focusStart) { ValDef(Modifiers(PARAM | SYNTHETIC), @@ -4403,31 +4374,43 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper treeCopy.New(tree, tpt1).setType(tp) } - def functionTypeWildcard(tree: Tree, arity: Int): Type = { - val tp = functionType(List.fill(arity)(WildcardType), WildcardType) - if (tp == NoType) MaxFunctionArityError(tree) - tp - } - - def typedEta(expr1: Tree): Tree = expr1.tpe match { - case TypeRef(_, ByNameParamClass, _) => - val expr2 = Function(List(), expr1) setPos expr1.pos - new ChangeOwnerTraverser(context.owner, expr2.symbol).traverse(expr2) - typed1(expr2, mode, pt) - case NullaryMethodType(restpe) => - val expr2 = Function(List(), expr1) setPos expr1.pos - new ChangeOwnerTraverser(context.owner, expr2.symbol).traverse(expr2) - typed1(expr2, mode, pt) - case PolyType(_, MethodType(formals, _)) => - if (isFunctionType(pt)) expr1 - else adapt(expr1, mode, functionTypeWildcard(expr1, formals.length)) - case MethodType(formals, _) => - if (isFunctionType(pt)) expr1 - else adapt(expr1, mode, functionTypeWildcard(expr1, formals.length)) + def functionTypeWildcard(arity: Int): Type = + functionType(List.fill(arity)(WildcardType), WildcardType) + + def checkArity(tree: Tree)(tp: Type): tp.type = tp match { + case NoType => MaxFunctionArityError(tree); tp + case _ => tp + } + + + /** Eta expand an expression like `m _`, where `m` denotes a method or a by-name argument + * + * The spec says: + * The expression `$e$ _` is well-formed if $e$ is of method type or if $e$ is a call-by-name parameter. + * (1) If $e$ is a method with parameters, `$e$ _` represents $e$ converted to a function type + * by [eta expansion](#eta-expansion). + * (2) If $e$ is a parameterless method or call-by-name parameter of type `=>$T$`, `$e$ _` represents + * the function of type `() => $T$`, which evaluates $e$ when it is applied to the empty parameterlist `()`. + */ + def typedEta(methodValue: Tree): Tree = methodValue.tpe match { + case tp@(MethodType(_, _) | PolyType(_, MethodType(_, _))) => // (1) + val formals = tp.params + if (isFunctionType(pt) || samMatchesFunctionBasedOnArity(samOf(pt), formals)) methodValue + else adapt(methodValue, mode, checkArity(methodValue)(functionTypeWildcard(formals.length))) + + case TypeRef(_, ByNameParamClass, _) | NullaryMethodType(_) => // (2) + val pos = methodValue.pos + // must create it here to change owner (normally done by typed's typedFunction) + val funSym = context.owner.newAnonymousFunctionValue(pos) + new ChangeOwnerTraverser(context.owner, funSym) traverse methodValue + + typed(Function(List(), methodValue) setSymbol funSym setPos pos, mode, pt) + case ErrorType => - expr1 + methodValue + case _ => - UnderscoreEtaError(expr1) + UnderscoreEtaError(methodValue) } def tryTypedArgs(args: List[Tree], mode: Mode): Option[List[Tree]] = { @@ -4471,7 +4454,7 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper case Annotated(_, r) => treesInResult(r) case If(_, t, e) => treesInResult(t) ++ treesInResult(e) case Try(b, catches, _) => treesInResult(b) ++ catches - case Typed(r, Function(Nil, EmptyTree)) => treesInResult(r) + case Typed(r, Function(Nil, EmptyTree)) => treesInResult(r) // a method value case Select(qual, name) => treesInResult(qual) case Apply(fun, args) => treesInResult(fun) ++ args.flatMap(treesInResult) case TypeApply(fun, args) => treesInResult(fun) ++ args.flatMap(treesInResult) @@ -4490,7 +4473,7 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper tryTypedArgs(args, forArgMode(fun, mode)) match { case Some(args1) if !args1.exists(arg => arg.exists(_.isErroneous)) => val qual1 = - if (!pt.isError) adaptToArguments(qual, name, args1, pt, reportAmbiguous = true, saveErrors = true) + if (!pt.isError) adaptToArguments(qual, name, args1, pt) else qual if (qual1 ne qual) { val tree1 = Apply(Select(qual1, name) setPos fun.pos, args1) setPos tree.pos @@ -4717,7 +4700,7 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper // member. Added `| PATTERNmode` to allow enrichment in patterns (so we can add e.g., an // xml member to StringContext, which in turn has an unapply[Seq] method) if (name != nme.CONSTRUCTOR && mode.inAny(EXPRmode | PATTERNmode)) { - val qual1 = adaptToMemberWithArgs(tree, qual, name, mode, reportAmbiguous = true, saveErrors = true) + val qual1 = adaptToMemberWithArgs(tree, qual, name, mode) if ((qual1 ne qual) && !qual1.isErrorTyped) return typed(treeCopy.Select(tree, qual1, name), mode, pt) } @@ -5111,11 +5094,11 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper // because `expr` might contain nested macro calls (see SI-6673) // // Note: apparently `Function(Nil, EmptyTree)` is the secret parser marker - // which means trailing underscore. + // which means trailing underscore -- denoting a method value. See makeMethodValue in TreeBuilder. case Typed(expr, Function(Nil, EmptyTree)) => typed1(suppressMacroExpansion(expr), mode, pt) match { case macroDef if treeInfo.isMacroApplication(macroDef) => MacroEtaError(macroDef) - case exprTyped => typedEta(checkDead(exprTyped)) + case methodValue => typedEta(checkDead(methodValue)) } case Typed(expr, tpt) => val tpt1 = typedType(tpt, mode) // type the ascribed type first |