diff options
| -rw-r--r-- | src/compiler/scala/tools/nsc/transform/TailCalls.scala | 16 | ||||
| -rw-r--r-- | test/files/run/t6089.check | 1 | ||||
| -rw-r--r-- | test/files/run/t6089.scala | 13 |
3 files changed, 25 insertions, 5 deletions
diff --git a/src/compiler/scala/tools/nsc/transform/TailCalls.scala b/src/compiler/scala/tools/nsc/transform/TailCalls.scala index 4c9d855413..d5bbc578fc 100644 --- a/src/compiler/scala/tools/nsc/transform/TailCalls.scala +++ b/src/compiler/scala/tools/nsc/transform/TailCalls.scala @@ -373,7 +373,7 @@ abstract class TailCalls extends Transform { // the labels all look like: matchEnd(x) {x} // then, in a forward jump `matchEnd(expr)`, `expr` is considered in tail position (and the matchEnd jump is replaced by the jump generated by expr) class TailPosLabelsTraverser extends Traverser { - val tailLabels = new collection.mutable.ListBuffer[Symbol]() + val tailLabels = new collection.mutable.HashSet[Symbol]() private var maybeTail: Boolean = true // since we start in the rhs of a DefDef @@ -388,9 +388,15 @@ abstract class TailCalls extends Transform { def traverseTreesNoTail(trees: List[Tree]) = trees foreach traverseNoTail override def traverse(tree: Tree) = tree match { - case LabelDef(_, List(arg), body@Ident(_)) if arg.symbol == body.symbol => // we're looking for label(x){x} in tail position, since that means `a` is in tail position in a call `label(a)` + // we're looking for label(x){x} in tail position, since that means `a` is in tail position in a call `label(a)` + case LabelDef(_, List(arg), body@Ident(_)) if arg.symbol == body.symbol => if (maybeTail) tailLabels += tree.symbol + // jumps to matchEnd are transparent; need this case for nested matches + // (and the translated match case below does things in reverse for this case's sake) + case Apply(fun, arg :: Nil) if hasSynthCaseSymbol(fun) && tailLabels(fun.symbol) => + traverse(arg) + // a translated casedef case LabelDef(_, _, body) if hasSynthCaseSymbol(tree) => traverse(body) @@ -400,9 +406,9 @@ abstract class TailCalls extends Transform { // the assumption is once we encounter a case, the remainder of the block will consist of cases // the prologue may be empty, usually it is the valdef that stores the scrut val (prologue, cases) = stats span (s => !s.isInstanceOf[LabelDef]) - traverseTreesNoTail(prologue) // selector (may be absent) - traverseTrees(cases) traverse(expr) + traverseTrees(cases.reverse) // reverse so that we enter the matchEnd LabelDef before we see jumps to it + traverseTreesNoTail(prologue) // selector (may be absent) case CaseDef(pat, guard, body) => traverse(body) @@ -426,7 +432,7 @@ abstract class TailCalls extends Transform { traverseTreesNoTail(catches) traverseNoTail(finalizer) - case EmptyTree | Super(_, _) | This(_) | Select(_, _) | Ident(_) | Literal(_) | Function(_, _) | TypeTree() => + case Apply(_, _) | EmptyTree | Super(_, _) | This(_) | Select(_, _) | Ident(_) | Literal(_) | Function(_, _) | TypeTree() => case _ => super.traverse(tree) } } diff --git a/test/files/run/t6089.check b/test/files/run/t6089.check new file mode 100644 index 0000000000..a8d4424106 --- /dev/null +++ b/test/files/run/t6089.check @@ -0,0 +1 @@ +scala.MatchError: Foo(0) (of class Foo) diff --git a/test/files/run/t6089.scala b/test/files/run/t6089.scala new file mode 100644 index 0000000000..c72d7ba792 --- /dev/null +++ b/test/files/run/t6089.scala @@ -0,0 +1,13 @@ +case class Foo(x: Int) + +object Test { + def bippo(result: Boolean): Boolean = result + def bungus(m: Foo): Boolean = + bippo(m match { case Foo(2) => bungus(m) }) + + def main(args: Array[String]): Unit = try { + bungus(Foo(0)) + } catch { + case x: MatchError => println(x) + } +}
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