From 5b8327b807c40cab867065cf695191a36c9210ee Mon Sep 17 00:00:00 2001 From: Jason Zaugg Date: Tue, 7 May 2013 23:29:02 +0200 Subject: SI-7459 Handle pattern binders used as prefixes in TypeTrees. Match translation was incorrect for: case t => new t.C case D(t) => new d.C We would end up with Types in TypeTrees referring to the wrong symbols, e.g: // t7459a.scala ((x0$1: this.LM) => { case val x1: this.LM = x0$1; case4(){ matchEnd3(new tttt.Node[Any]()) }; matchEnd3(x: Any){ x } Or: // t7459b.scala ((x0$1: CC) => { case val x1: CC = x0$1; case4(){ if (x1.ne(null)) matchEnd3(new tttt.Node[Any]()) else case5() }; This commit: - Changes `bindSubPats` to traverse types, as well as terms, in search of references to bound symbols - Changes `Substitution` to reuse `Tree#substituteSymbols` rather than the home-brew substitution from `Tree`s to `Tree`s, if the `to` trees are all `Ident`s - extends `substIdentsForTrees` to substitute selections like `x1.caseField` into types. I had to dance around the awkward handling of "swatches" (exception handlers that can be implemented with JVM native type switches) by duplicating trees to avoid seeing the results of `substituteSymbols` in `caseDefs` after we abandon that approach if we detect the patterns are too complex late in the game. I also had to add an escape hatch for the "type selection from volatile type" check in the type checker. Without this, the translation of `pos/t7459c.scala`: case val x1: _$1 = (null: Test.Mirror[_]).universe; case5(){ if (x1.isInstanceOf[Test.JavaUniverse]) { val x2: _$1 with Test.JavaUniverse = (x1.asInstanceOf[_$1 with Test.JavaUniverse]: _$1 with Test.JavaUniverse); matchEnd4({ val ju1: Test.JavaUniverse = x2; val f: () => x2.Type = (() => (null: x2.TypeTag[Nothing]).tpe); .. triggers that error at `x2.TypeTag`. --- .../tools/nsc/transform/patmat/MatchAnalysis.scala | 2 +- .../nsc/transform/patmat/MatchTranslation.scala | 7 ++-- .../nsc/transform/patmat/MatchTreeMaking.scala | 11 ++++++- .../nsc/transform/patmat/PatternMatching.scala | 38 ++++++++++++++++++---- .../scala/tools/nsc/typechecker/Typers.scala | 8 +++-- 5 files changed, 53 insertions(+), 13 deletions(-) (limited to 'src') diff --git a/src/compiler/scala/tools/nsc/transform/patmat/MatchAnalysis.scala b/src/compiler/scala/tools/nsc/transform/patmat/MatchAnalysis.scala index 21e90b1d78..50fa38e44d 100644 --- a/src/compiler/scala/tools/nsc/transform/patmat/MatchAnalysis.scala +++ b/src/compiler/scala/tools/nsc/transform/patmat/MatchAnalysis.scala @@ -266,7 +266,7 @@ trait MatchApproximation extends TreeAndTypeAnalysis with ScalaLogic with MatchT // the type of the binder passed to the first invocation // determines the type of the tree that'll be returned for that binder as of then final def binderToUniqueTree(b: Symbol) = - unique(accumSubst(normalize(CODE.REF(b))), b.tpe) + unique(accumSubst(normalize(gen.mkAttributedStableRef(b))), b.tpe) // note that the sequencing of operations is important: must visit in same order as match execution // binderToUniqueTree uses the type of the first symbol that was encountered as the type for all future binders diff --git a/src/compiler/scala/tools/nsc/transform/patmat/MatchTranslation.scala b/src/compiler/scala/tools/nsc/transform/patmat/MatchTranslation.scala index d862805a07..27360fea53 100644 --- a/src/compiler/scala/tools/nsc/transform/patmat/MatchTranslation.scala +++ b/src/compiler/scala/tools/nsc/transform/patmat/MatchTranslation.scala @@ -248,7 +248,10 @@ trait MatchTranslation { if (caseDefs forall treeInfo.isCatchCase) caseDefs else { val swatches = { // switch-catches - val bindersAndCases = caseDefs map { caseDef => + // SI-7459 must duplicate here as we haven't commited to switch emission, and just figuring out + // if we can ends up mutating `caseDefs` down in the use of `substituteSymbols` in + // `TypedSubstitution#Substitution`. That is called indirectly by `emitTypeSwitch`. + val bindersAndCases = caseDefs.map(_.duplicate) map { caseDef => // generate a fresh symbol for each case, hoping we'll end up emitting a type-switch (we don't have a global scrut there) // if we fail to emit a fine-grained switch, have to do translateCase again with a single scrutSym (TODO: uniformize substitution on treemakers so we can avoid this) val caseScrutSym = freshSym(pos, pureType(ThrowableTpe)) @@ -518,7 +521,7 @@ trait MatchTranslation { // reference the (i-1)th case accessor if it exists, otherwise the (i-1)th tuple component override protected def tupleSel(binder: Symbol)(i: Int): Tree = { val accessors = binder.caseFieldAccessors - if (accessors isDefinedAt (i-1)) REF(binder) DOT accessors(i-1) + if (accessors isDefinedAt (i-1)) gen.mkAttributedStableRef(binder) DOT accessors(i-1) else codegen.tupleSel(binder)(i) // this won't type check for case classes, as they do not inherit ProductN } } diff --git a/src/compiler/scala/tools/nsc/transform/patmat/MatchTreeMaking.scala b/src/compiler/scala/tools/nsc/transform/patmat/MatchTreeMaking.scala index 3abec521df..fb63ca7dc3 100644 --- a/src/compiler/scala/tools/nsc/transform/patmat/MatchTreeMaking.scala +++ b/src/compiler/scala/tools/nsc/transform/patmat/MatchTreeMaking.scala @@ -166,8 +166,17 @@ trait MatchTreeMaking extends MatchCodeGen with Debugging { val usedBinders = new mutable.HashSet[Symbol]() // all potentially stored subpat binders val potentiallyStoredBinders = stored.unzip._1.toSet + def ref(sym: Symbol) = + if (potentiallyStoredBinders(sym)) usedBinders += sym // compute intersection of all symbols in the tree `in` and all potentially stored subpat binders - in.foreach(t => if (potentiallyStoredBinders(t.symbol)) usedBinders += t.symbol) + in.foreach { + case tt: TypeTree => + tt.tpe foreach { // SI-7459 e.g. case Prod(t) => new t.u.Foo + case SingleType(_, sym) => ref(sym) + case _ => + } + case t => ref(t.symbol) + } if (usedBinders.isEmpty) in else { diff --git a/src/compiler/scala/tools/nsc/transform/patmat/PatternMatching.scala b/src/compiler/scala/tools/nsc/transform/patmat/PatternMatching.scala index ef50e083a1..d35aad964d 100644 --- a/src/compiler/scala/tools/nsc/transform/patmat/PatternMatching.scala +++ b/src/compiler/scala/tools/nsc/transform/patmat/PatternMatching.scala @@ -12,7 +12,7 @@ import scala.language.postfixOps import scala.tools.nsc.transform.TypingTransformers import scala.tools.nsc.transform.Transform import scala.reflect.internal.util.Statistics -import scala.reflect.internal.Types +import scala.reflect.internal.{Mode, Types} import scala.reflect.internal.util.Position /** Translate pattern matching. @@ -198,33 +198,57 @@ trait Interface extends ast.TreeDSL { } class Substitution(val from: List[Symbol], val to: List[Tree]) { - import global.{Transformer, Ident, NoType} + import global.{Transformer, Ident, NoType, TypeTree, SingleType} // We must explicitly type the trees that we replace inside some other tree, since the latter may already have been typed, // and will thus not be retyped. This means we might end up with untyped subtrees inside bigger, typed trees. def apply(tree: Tree): Tree = { // according to -Ystatistics 10% of translateMatch's time is spent in this method... // since about half of the typedSubst's end up being no-ops, the check below shaves off 5% of the time spent in typedSubst - if (!tree.exists { case i@Ident(_) => from contains i.symbol case _ => false}) tree - else (new Transformer { + val toIdents = to.forall(_.isInstanceOf[Ident]) + val containsSym = tree.exists { + case i@Ident(_) => from contains i.symbol + case tt: TypeTree => tt.tpe.exists { + case SingleType(_, sym) => + (from contains sym) && { + if (!toIdents) global.devWarning(s"Unexpected substitution of non-Ident into TypeTree `$tt`, subst= $this") + true + } + case _ => false + } + case _ => false + } + val toSyms = to.map(_.symbol) + object substIdentsForTrees extends Transformer { private def typedIfOrigTyped(to: Tree, origTp: Type): Tree = if (origTp == null || origTp == NoType) to // important: only type when actually substing and when original tree was typed // (don't need to use origTp as the expected type, though, and can't always do this anyway due to unknown type params stemming from polymorphic extractors) else typer.typed(to) + def typedStable(t: Tree) = typer.typed(t.shallowDuplicate, Mode.MonoQualifierModes | Mode.TYPEPATmode) + lazy val toTypes: List[Type] = to map (tree => typedStable(tree).tpe) + override def transform(tree: Tree): Tree = { def subst(from: List[Symbol], to: List[Tree]): Tree = if (from.isEmpty) tree - else if (tree.symbol == from.head) typedIfOrigTyped(to.head.shallowDuplicate.setPos(tree.pos), tree.tpe) + else if (tree.symbol == from.head) typedIfOrigTyped(typedStable(to.head).setPos(tree.pos), tree.tpe) else subst(from.tail, to.tail) - tree match { + val tree1 = tree match { case Ident(_) => subst(from, to) case _ => super.transform(tree) } + tree1.modifyType(_.substituteTypes(from, toTypes)) } - }).transform(tree) + } + if (containsSym) { + if (to.forall(_.isInstanceOf[Ident])) + tree.duplicate.substituteSymbols(from, to.map(_.symbol)) // SI-7459 catches `case t => new t.Foo` + else + substIdentsForTrees.transform(tree) + } + else tree } diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala index 70acb03584..f93f8a781d 100644 --- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala +++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala @@ -3727,8 +3727,12 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper case TypeRef(pre, sym, args) => if (sym.isAliasType && containsLocal(tp) && (tp.dealias ne tp)) apply(tp.dealias) else { - if (pre.isVolatile) - InferTypeWithVolatileTypeSelectionError(tree, pre) + if (pre.isVolatile) pre match { + case SingleType(_, sym) if sym.isSynthetic && isPastTyper => + debuglog(s"ignoring volatility of prefix in pattern matcher generated inferred type: $tp") // See pos/t7459c.scala + case _ => + InferTypeWithVolatileTypeSelectionError(tree, pre) + } mapOver(tp) } case _ => -- cgit v1.2.3