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SI-6955 switch emission no longer foiled by type alias

dealiasWiden the type of the scrutinee before checking it's switchable
now with tests! (using IcodeTest since javap is not available everywhere)

rebase of #1879
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1 parent 64ec51b commit 38958f458cec09dacece690b2376d96fc7758972 @adriaanm adriaanm committed Jan 10, 2013
@@ -3520,7 +3520,7 @@ 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.dealiasWiden)) {
val caseDefsWithDefault = regularSwitchMaker(cases map {c => (scrutSym, c)}, pt)
if (caseDefsWithDefault isEmpty) None // not worth emitting a switch.
else {
@@ -0,0 +1 @@
+2
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@@ -0,0 +1,28 @@
+import scala.tools.partest.IcodeTest
+
+// this class should compile to code that uses switches (twice)
+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
+ }
+
+ // this worked before, should keep working
+ def switchOkay(i: Byte): Int = i match {
+ 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)
+}
+

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