allow disabling patmat analyses: -Xno-patmat-analysis

4 files changed, 13 insertions, 8 deletions

diff --git a/src/compiler/scala/reflect/internal/settings/MutableSettings.scala b/src/compiler/scala/reflect/internal/settings/MutableSettings.scala
index 45ba4ed3e6..8640a23aa7 100644
--- a/src/compiler/scala/reflect/internal/settings/MutableSettings.scala
+++ b/src/compiler/scala/reflect/internal/settings/MutableSettings.scala
@@ -44,4 +44,5 @@ abstract class MutableSettings extends AbsSettings {
   def maxClassfileName: IntSetting
   def Xexperimental: BooleanSetting
   def XoldPatmat: BooleanSetting
+  def XnoPatmatAnalysis: BooleanSetting
 }
\ No newline at end of file
diff --git a/src/compiler/scala/reflect/runtime/Settings.scala b/src/compiler/scala/reflect/runtime/Settings.scala
index bbe4d60e9c..b247797c6c 100644
--- a/src/compiler/scala/reflect/runtime/Settings.scala
+++ b/src/compiler/scala/reflect/runtime/Settings.scala
@@ -35,4 +35,5 @@ class Settings extends internal.settings.MutableSettings {
   val Xexperimental = new BooleanSetting(false)
   val deepCloning = new BooleanSetting (false)
   val XoldPatmat = new BooleanSetting(false)
+  val XnoPatmatAnalysis = new BooleanSetting(false)
 }
diff --git a/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala b/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
index efde2cee25..88a89d54eb 100644
--- a/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
+++ b/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
@@ -109,6 +109,7 @@ trait ScalaSettings extends AbsScalaSettings
   val sourceReader  = StringSetting     ("-Xsource-reader", "classname", "Specify a custom method for reading source files.", "")
 
   val XoldPatmat    = BooleanSetting    ("-Xoldpatmat", "Use the pre-2.10 pattern matcher. Otherwise, the 'virtualizing' pattern matcher is used in 2.10.")
+  val XnoPatmatAnalysis = BooleanSetting ("-Xno-patmat-analysis", "Don't perform exhaustivity/unreachability analysis. Also, ignore @switch annotation.")
 
   /** Compatibility stubs for options whose value name did
    *  not previously match the option name.
diff --git a/src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala b/src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala
index 5f8ae240cc..3b2c4d06c4 100644
--- a/src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala
@@ -1115,14 +1115,16 @@ trait PatternMatching extends Transform with TypingTransformers with ast.TreeDSL
         def isSwitchAnnotation(tpe: Type) = tpe hasAnnotation SwitchClass
         def isUncheckedAnnotation(tpe: Type) = tpe hasAnnotation UncheckedClass
 
-        val (unchecked, requireSwitch) = scrut match {
-          case Typed(_, tpt) =>
-            (isUncheckedAnnotation(tpt.tpe),
-             // matches with two or fewer cases need not apply for switchiness (if-then-else will do)
-             isSwitchAnnotation(tpt.tpe) && casesNoSubstOnly.lengthCompare(2) > 0)
-          case _ =>
-            (false, false)
-        }
+        val (unchecked, requireSwitch) =
+          if (settings.XnoPatmatAnalysis.value) (true, false)
+          else scrut match {
+            case Typed(_, tpt) =>
+              (isUncheckedAnnotation(tpt.tpe),
+               // matches with two or fewer cases need not apply for switchiness (if-then-else will do)
+               isSwitchAnnotation(tpt.tpe) && casesNoSubstOnly.lengthCompare(2) > 0)
+            case _ =>
+              (false, false)
+          }
 
         emitSwitch(scrut, scrutSym, casesNoSubstOnly, pt, matchFailGenOverride).getOrElse{
           if (requireSwitch) typer.context.unit.warning(scrut.pos, "could not emit switch for @switch annotated match")