Permalink
Browse files

SI-6955 switch emission no longer foiled by type alias

dealias the type of the scrutinee before checking it's switchable
now with tests! (using IcodeTest since javap is not available everywhere)
  • Loading branch information...
1 parent f219ade commit 8475807f540a698c8456bc113b9c5b9186ee2cf5 @adriaanm adriaanm committed Jan 10, 2013
@@ -3527,7 +3527,7 @@ trait PatternMatching extends Transform with TypingTransformers with ast.TreeDSL
override def emitSwitch(scrut: Tree, scrutSym: Symbol, cases: List[List[TreeMaker]], pt: Type, matchFailGenOverride: Option[Tree => Tree], unchecked: Boolean): Option[Tree] = { import CODE._
val regularSwitchMaker = new RegularSwitchMaker(scrutSym, matchFailGenOverride, unchecked)
// TODO: if patterns allow switch but the type of the scrutinee doesn't, cast (type-test) the scrutinee to the corresponding switchable type and switch on the result
- if (regularSwitchMaker.switchableTpe(scrutSym.tpe)) {
+ if (regularSwitchMaker.switchableTpe(scrutSym.tpe.dealias)) { // TODO: switch to dealiasWiden in 2.11
val caseDefsWithDefault = regularSwitchMaker(cases map {c => (scrutSym, c)}, pt)
if (caseDefsWithDefault isEmpty) None // not worth emitting a switch.
else {
@@ -0,0 +1 @@
+2
View
@@ -0,0 +1,26 @@
+import scala.tools.partest.IcodeTest
+
+class Switches {
+ type Tag = Byte
+
+ def switchBad(i: Tag): Int = i match { // notice type of i is Tag = Byte
+ case 1 => 1
+ case 2 => 2
+ case 3 => 3
+ case _ => 0
+ }
+
+ def switchOkay(i: Byte): Int = i match { // notice type of i is Byte
+ case 1 => 1
+ case 2 => 2
+ case 3 => 3
+ case _ => 0
+ }
+}
+
+object Test extends IcodeTest {
+ // ensure we get two switches out of this -- ignore the rest of the output for robustness
+ // exclude the constant we emit for the "SWITCH ..." string below (we get the icode for all the code you see in this file)
+ override def show() = println(collectIcode("").filter(x => x.indexOf("SWITCH ...") >= 0 && x.indexOf("CONSTANT(") == -1).size)
+}
+

0 comments on commit 8475807

Please sign in to comment.