diff options
Diffstat (limited to 'src/compiler/scala/tools/nsc/transform/patmat/MatchOptimization.scala')
| -rw-r--r-- | src/compiler/scala/tools/nsc/transform/patmat/MatchOptimization.scala | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/src/compiler/scala/tools/nsc/transform/patmat/MatchOptimization.scala b/src/compiler/scala/tools/nsc/transform/patmat/MatchOptimization.scala index dcf2413b15..23889058d3 100644 --- a/src/compiler/scala/tools/nsc/transform/patmat/MatchOptimization.scala +++ b/src/compiler/scala/tools/nsc/transform/patmat/MatchOptimization.scala @@ -22,7 +22,7 @@ import scala.reflect.internal.util.NoPosition trait MatchOptimization extends MatchTreeMaking with MatchAnalysis { import PatternMatchingStats._ import global.{Tree, Type, Symbol, NoSymbol, CaseDef, atPos, - ConstantType, Literal, Constant, gen, EmptyTree, + ConstantType, Literal, Constant, gen, EmptyTree, distinctBy, Typed, treeInfo, nme, Ident, Apply, If, Bind, lub, Alternative, deriveCaseDef, Match, MethodType, LabelDef, TypeTree, Throw} @@ -442,7 +442,7 @@ trait MatchOptimization extends MatchTreeMaking with MatchAnalysis { case SwitchableTreeMaker(pattern) :: GuardAndBodyTreeMakers(guard, body) => Some(CaseDef(pattern, guard, body)) // alternatives - case AlternativesTreeMaker(_, altss, _) :: GuardAndBodyTreeMakers(guard, body) if alternativesSupported => + case AlternativesTreeMaker(_, altss, pos) :: GuardAndBodyTreeMakers(guard, body) if alternativesSupported => val switchableAlts = altss map { case SwitchableTreeMaker(pattern) :: Nil => Some(pattern) @@ -452,7 +452,17 @@ trait MatchOptimization extends MatchTreeMaking with MatchAnalysis { // succeed if they were all switchable sequence(switchableAlts) map { switchableAlts => - CaseDef(Alternative(switchableAlts), guard, body) + def extractConst(t: Tree) = t match { + case Literal(const) => const + case _ => t + } + // SI-7290 Discard duplicate alternatives that would crash the backend + def distinctAlts = distinctBy(switchableAlts)(extractConst) + if (distinctAlts.size < switchableAlts.size) { + val duplicated = switchableAlts.groupBy(extractConst).flatMap(_._2.drop(1)) + global.currentUnit.warning(pos, s"Pattern contains duplicate alternatives: ${duplicated.mkString(", ")}") + } + CaseDef(Alternative(distinctAlts), guard, body) } case _ => // debug.patmat("can't emit switch for "+ makers) |