diff options
Diffstat (limited to 'src/compiler')
-rw-r--r-- | src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala | 23 | ||||
-rw-r--r-- | src/compiler/scala/tools/nsc/typechecker/Typers.scala | 85 |
2 files changed, 84 insertions, 24 deletions
diff --git a/src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala b/src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala index 4a765ea22e..f7579ad249 100644 --- a/src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala +++ b/src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala @@ -109,9 +109,6 @@ trait PatternMatching extends Transform with TypingTransformers with ast.TreeDSL import definitions._ import analyzer._ //Typer - - case class DefaultOverrideMatchAttachment(default: Tree) - object vpmName { val one = newTermName("one") val drop = newTermName("drop") @@ -222,11 +219,11 @@ trait PatternMatching extends Transform with TypingTransformers with ast.TreeDSL // However this is a pain (at least the way I'm going about it) // and I have to think these detailed errors are primarily useful // for beginners, not people writing nested pattern matches. - def checkMatchVariablePatterns(m: Match) { + def checkMatchVariablePatterns(cases: List[CaseDef]) { // A string describing the first variable pattern var vpat: String = null // Using an iterator so we can recognize the last case - val it = m.cases.iterator + val it = cases.iterator def addendum(pat: Tree) = { matchingSymbolInScope(pat) match { @@ -269,7 +266,15 @@ trait PatternMatching extends Transform with TypingTransformers with ast.TreeDSL */ def translateMatch(match_ : Match): Tree = { val Match(selector, cases) = match_ - checkMatchVariablePatterns(match_) + + val (nonSyntheticCases, defaultOverride) = cases match { + case init :+ last if treeInfo isSyntheticDefaultCase last => + (init, Some(((scrut: Tree) => last.body))) + case _ => + (cases, None) + } + + checkMatchVariablePatterns(nonSyntheticCases) // we don't transform after uncurry // (that would require more sophistication when generating trees, @@ -296,14 +301,10 @@ trait PatternMatching extends Transform with TypingTransformers with ast.TreeDSL // val packedPt = repeatedToSeq(typer.packedType(match_, context.owner)) - // the alternative to attaching the default case override would be to simply - // append the default to the list of cases and suppress the unreachable case error that may arise (once we detect that...) - val matchFailGenOverride = match_.attachments.get[DefaultOverrideMatchAttachment].map{case DefaultOverrideMatchAttachment(default) => ((scrut: Tree) => default)} - val selectorSym = freshSym(selector.pos, pureType(selectorTp)) setFlag treeInfo.SYNTH_CASE_FLAGS // pt = Any* occurs when compiling test/files/pos/annotDepMethType.scala with -Xexperimental - val combined = combineCases(selector, selectorSym, cases map translateCase(selectorSym, pt), pt, matchOwner, matchFailGenOverride) + val combined = combineCases(selector, selectorSym, nonSyntheticCases map translateCase(selectorSym, pt), pt, matchOwner, defaultOverride) if (Statistics.canEnable) Statistics.stopTimer(patmatNanos, start) combined diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala index 2103f669c3..dc5491a509 100644 --- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala +++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala @@ -30,7 +30,6 @@ trait Typers extends Modes with Adaptations with Tags { import global._ import definitions._ import TypersStats._ - import patmat.DefaultOverrideMatchAttachment final def forArgMode(fun: Tree, mode: Int) = if (treeInfo.isSelfOrSuperConstrCall(fun)) mode | SCCmode @@ -2604,8 +2603,13 @@ trait Typers extends Modes with Adaptations with Tags { def mkParam(methodSym: Symbol, tp: Type = argTp) = methodSym.newValueParameter(paramName, paramPos.focus, SYNTHETIC) setInfo tp + def mkDefaultCase(body: Tree) = + atPos(tree.pos.makeTransparent) { + CaseDef(Bind(nme.DEFAULT_CASE, Ident(nme.WILDCARD)), body) + } + // `def applyOrElse[A1 <: $argTp, B1 >: $matchResTp](x: A1, default: A1 => B1): B1 = - // ${`$selector match { $cases }` updateAttachment DefaultOverrideMatchAttachment(REF(default) APPLY (REF(x)))}` + // ${`$selector match { $cases; case default$ => default(x) }` def applyOrElseMethodDef = { val methodSym = anonClass.newMethod(nme.applyOrElse, tree.pos, FINAL | OVERRIDE) @@ -2614,7 +2618,7 @@ trait Typers extends Modes with Adaptations with Tags { val x = mkParam(methodSym, A1.tpe) // applyOrElse's default parameter: - val B1 = methodSym newTypeParameter (newTypeName("B1")) setInfo TypeBounds.empty //lower(resTp) + val B1 = methodSym newTypeParameter (newTypeName("B1")) setInfo TypeBounds.empty val default = methodSym newValueParameter (newTermName("default"), tree.pos.focus, SYNTHETIC) setInfo functionType(List(A1.tpe), B1.tpe) val paramSyms = List(x, default) @@ -2624,19 +2628,72 @@ trait Typers extends Modes with Adaptations with Tags { // should use the DefDef for the context's tree, but it doesn't exist yet (we need the typer we're creating to create it) paramSyms foreach (methodBodyTyper.context.scope enter _) - val match_ = methodBodyTyper.typedMatch(selector, cases, mode, resTp) + // First, type without the default case; only the cases provided + // by the user are typed. The LUB of these becomes `B`, the lower + // bound of `B1`, which in turn is the result type of the default + // case + val match0 = methodBodyTyper.typedMatch(selector, cases, mode, resTp) + val matchResTp = match0.tpe - val matchResTp = match_.tpe B1 setInfo TypeBounds.lower(matchResTp) // patch info + // the default uses applyOrElse's first parameter since the scrut's type has been widened + val match_ = { + val defaultCase = methodBodyTyper.typedCase( + mkDefaultCase(methodBodyTyper.typed1(REF(default) APPLY (REF(x)), mode, B1.tpe).setType(B1.tpe)), argTp, B1.tpe) + treeCopy.Match(match0, match0.selector, match0.cases :+ defaultCase) + } match_ setType B1.tpe - // the default uses applyOrElse's first parameter since the scrut's type has been widened - val matchWithDefault = match_ updateAttachment DefaultOverrideMatchAttachment(REF(default) APPLY (REF(x))) - (DefDef(methodSym, methodBodyTyper.virtualizedMatch(matchWithDefault, mode, B1.tpe)), matchResTp) + // SI-6187 Do you really want to know? Okay, here's what's going on here. + // + // Well behaved trees satisfy the property: + // + // typed(tree) == typed(resetLocalAttrs(typed(tree)) + // + // Trees constructed without low-level symbol manipulation get this for free; + // references to local symbols are cleared by `ResetAttrs`, but bind to the + // corresponding symbol in the re-typechecked tree. But PartialFunction synthesis + // doesn't play by these rules. + // + // During typechecking of method bodies, references to method type parameter from + // the declared types of the value parameters should bind to a fresh set of skolems, + // which have been entered into scope by `Namer#methodSig`. A comment therein: + // + // "since the skolemized tparams are in scope, the TypeRefs in vparamSymss refer to skolemized tparams" + // + // But, if we retypecheck the reset `applyOrElse`, the TypeTree of the `default` + // parameter contains no type. Somehow (where?!) it recovers a type that is _almost_ okay: + // `A1 => B1`. But it should really be `A1&0 => B1&0`. In the test, run/t6187.scala, this + // difference results in a type error, as `default.apply(x)` types as `B1`, which doesn't + // conform to the required `B1&0` + // + // I see three courses of action. + // + // 1) synthesize a `asInstanceOf[B1]` below (I tried this first. But... ewwww.) + // 2) install an 'original' TypeTree that will used after ResetAttrs (the solution below) + // 3) Figure out how the almost-correct type is recovered on re-typechecking, and + // substitute in the skolems. + // + // For 2.11, we'll probably shift this transformation back a phase or two, so macros + // won't be affected. But in any case, we should satisfy retypecheckability. + // + val originals: Map[Symbol, Tree] = { + def typedIdent(sym: Symbol) = methodBodyTyper.typedType(Ident(sym), mode) + val A1Tpt = typedIdent(A1) + val B1Tpt = typedIdent(B1) + Map( + x -> A1Tpt, + default -> gen.scalaFunctionConstr(List(A1Tpt), B1Tpt) + ) + } + val rhs = methodBodyTyper.virtualizedMatch(match_, mode, B1.tpe) + val defdef = DefDef(methodSym, Modifiers(methodSym.flags), originals, rhs) + + (defdef, matchResTp) } - // `def isDefinedAt(x: $argTp): Boolean = ${`$selector match { $casesTrue ` updateAttachment DefaultOverrideMatchAttachment(FALSE_typed)}` + // `def isDefinedAt(x: $argTp): Boolean = ${`$selector match { $casesTrue; case default$ => false } }` def isDefinedAtMethod = { val methodSym = anonClass.newMethod(nme.isDefinedAt, tree.pos.makeTransparent, FINAL) val paramSym = mkParam(methodSym) @@ -2645,10 +2702,10 @@ trait Typers extends Modes with Adaptations with Tags { methodBodyTyper.context.scope enter paramSym methodSym setInfo MethodType(List(paramSym), BooleanClass.tpe) - val match_ = methodBodyTyper.typedMatch(selector, casesTrue, mode, BooleanClass.tpe) + val defaultCase = mkDefaultCase(FALSE_typed) + val match_ = methodBodyTyper.typedMatch(selector, casesTrue :+ defaultCase, mode, BooleanClass.tpe) - val matchWithDefault = match_ updateAttachment DefaultOverrideMatchAttachment(FALSE_typed) - DefDef(methodSym, methodBodyTyper.virtualizedMatch(matchWithDefault, mode, BooleanClass.tpe)) + DefDef(methodSym, methodBodyTyper.virtualizedMatch(match_, mode, BooleanClass.tpe)) } // only used for @cps annotated partial functions @@ -2693,7 +2750,9 @@ trait Typers extends Modes with Adaptations with Tags { members foreach (m => anonClass.info.decls enter m.symbol) 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, ListOfNil, members, tree.pos.focus), atPos(tree.pos.focus)( + Apply(Select(New(Ident(anonClass.name).setSymbol(anonClass)), nme.CONSTRUCTOR), List()) + )) } if (typedBlock.isErrorTyped) typedBlock |