Avoid test-pickling failure.

odersky · odersky · commit f1a669b421ea · 2017-07-06T17:53:11.000+02:00
diff --git a/compiler/src/dotty/tools/dotc/transform/PatternMatcher.scala b/compiler/src/dotty/tools/dotc/transform/PatternMatcher.scala
@@ -898,9 +898,9 @@ object PatternMatcher {
           case Block(_, Match(_, cases)) => cases
           case _ => Nil
         }
-        def numConsts(cdefs: List[CaseDef]) = {
+        def numConsts(cdefs: List[CaseDef]): Int = {
           val tpes = cdefs.map(_.pat.tpe)
-          tpes.toSet.size
+          tpes.toSet.size: Int // without the type ascription, testPickling fails because of #2840.
         }
         if (numConsts(resultCases) < numConsts(original.cases))
           ctx.warning(i"could not emit switch for @switch annotated match", original.pos)

Original file line number	Diff line number	Diff line change
`@@ -898,9 +898,9 @@ object PatternMatcher {`
`898`	`898`	`case Block(_, Match(_, cases)) => cases`
`899`	`899`	`case _ => Nil`
`900`	`900`	`}`
`901`		`- def numConsts(cdefs: List[CaseDef]) = {`
	`901`	`+ def numConsts(cdefs: List[CaseDef]): Int = {`
`902`	`902`	`val tpes = cdefs.map(_.pat.tpe)`
`903`		`- tpes.toSet.size`
	`903`	`+ tpes.toSet.size: Int // without the type ascription, testPickling fails because of #2840.`
`904`	`904`	`}`
`905`	`905`	`if (numConsts(resultCases) < numConsts(original.cases))`
`906`	`906`	`ctx.warning(i"could not emit switch for @switch annotated match", original.pos)`