Merge pull request #5273 from retronym/ticket/9855

SI-9855 Fix regression in extractor pattern translation

4 files changed, 32 insertions, 17 deletions

diff --git a/src/compiler/scala/tools/nsc/transform/patmat/MatchTranslation.scala b/src/compiler/scala/tools/nsc/transform/patmat/MatchTranslation.scala
index e12b8548a8..5750f8f7e7 100644
--- a/src/compiler/scala/tools/nsc/transform/patmat/MatchTranslation.scala
+++ b/src/compiler/scala/tools/nsc/transform/patmat/MatchTranslation.scala
@@ -125,7 +125,7 @@ trait MatchTranslation {
         // TODO: paramType may contain unbound type params (run/t2800, run/t3530)
         val makers = (
           // Statically conforms to paramType
-          if (this ensureConformsTo paramType) treeMaker(binder, false, pos) :: Nil
+          if (tpe <:< paramType) treeMaker(binder, false, pos) :: Nil
           else typeTest :: extraction :: Nil
         )
         step(makers: _*)(extractor.subBoundTrees: _*)
@@ -162,16 +162,6 @@ trait MatchTranslation {
         setVarInfo(binder, paramType)
         true
       }
-      // If <:< but not =:=, no type test needed, but the tree maker relies on the binder having
-      // exactly paramType (and not just some type compatible with it.) SI-6624 shows this is necessary
-      // because apparently patBinder may have an unfortunate type (.decls don't have the case field
-      // accessors) TODO: get to the bottom of this -- I assume it happens when type checking
-      // infers a weird type for an unapply call. By going back to the parameterType for the
-      // extractor call we get a saner type, so let's just do that for now.
-      def ensureConformsTo(paramType: Type): Boolean = (
-           (tpe =:= paramType)
-        || (tpe <:< paramType) && setInfo(paramType)
-      )
 
       private def concreteType = tpe.bounds.hi
       private def unbound = unbind(tree)
@@ -396,7 +386,6 @@ trait MatchTranslation {
 
       /** Create the TreeMaker that embodies this extractor call
        *
-       * `binder` has been casted to `paramType` if necessary
        * `binderKnownNonNull` indicates whether the cast implies `binder` cannot be null
        * when `binderKnownNonNull` is `true`, `ProductExtractorTreeMaker` does not do a (redundant) null check on binder
        */
@@ -502,7 +491,7 @@ trait MatchTranslation {
        * when `binderKnownNonNull` is `true`, `ProductExtractorTreeMaker` does not do a (redundant) null check on binder
        */
       def treeMaker(binder: Symbol, binderKnownNonNull: Boolean, pos: Position): TreeMaker = {
-        val paramAccessors = binder.constrParamAccessors
+        val paramAccessors = aligner.wholeType.typeSymbol.constrParamAccessors
         val numParams = paramAccessors.length
         def paramAccessorAt(subPatIndex: Int) = paramAccessors(math.min(subPatIndex, numParams - 1))
         // binders corresponding to mutable fields should be stored (SI-5158, SI-6070)
@@ -531,7 +520,7 @@ trait MatchTranslation {
 
       // reference the (i-1)th case accessor if it exists, otherwise the (i-1)th tuple component
       override protected def tupleSel(binder: Symbol)(i: Int): Tree = {
-        val accessors = binder.caseFieldAccessors
+        val accessors = aligner.wholeType.typeSymbol.caseFieldAccessors
         if (accessors isDefinedAt (i-1)) gen.mkAttributedStableRef(binder) DOT accessors(i-1)
         else codegen.tupleSel(binder)(i) // this won't type check for case classes, as they do not inherit ProductN
       }
diff --git a/test/files/pos/t9855.scala b/test/files/pos/t9855.scala
new file mode 100644
index 0000000000..b6ac3e2432
--- /dev/null
+++ b/test/files/pos/t9855.scala
@@ -0,0 +1,10 @@
+class C {
+	def xx(verb: String, a: Array[Int]) {
+	  val reYYYY = """(\d\d\d\d)""".r
+	  verb match {
+	    case "time" if a.isEmpty =>
+	    case "time"              =>
+	    case reYYYY(y)           =>
+	  }
+	}
+}
diff --git a/test/files/pos/t9855b.scala b/test/files/pos/t9855b.scala
new file mode 100644
index 0000000000..30c58be3dc
--- /dev/null
+++ b/test/files/pos/t9855b.scala
@@ -0,0 +1,16 @@
+object Test {
+  var FALSE = false
+  def main(args: Array[String]): Unit = {
+    val SomeB = new B
+    new B() match {
+      case SomeB if FALSE =>
+      case SomeB =>
+      case Ext(_) =>
+    }
+  }
+}
+object Ext {
+  def unapply(s: A) = Some(())
+}
+class A
+class B extends A
diff --git a/test/files/run/t6288.check b/test/files/run/t6288.check
index 67877fd56d..7933f516a8 100644
--- a/test/files/run/t6288.check
+++ b/test/files/run/t6288.check
@@ -7,7 +7,7 @@
     };
     [21]def unapply([29]z: [32]<type: [32]scala.Any>): [21]Option[Int] = [56][52][52]scala.Some.apply[[52]Int]([58]-1);
     [64]{
-      [64]case <synthetic> val x1: [64]Any = [64]"";
+      [64]case <synthetic> val x1: [64]String = [64]"";
       [64]case5()[84]{
         [84]<synthetic> val o7: [84]Option[Int] = [84][84]Case3.unapply([84]x1);
         [84]if ([84]o7.isEmpty.unary_!)
@@ -30,7 +30,7 @@
     };
     [127]def unapplySeq([138]z: [141]<type: [141]scala.Any>): [127]Option[List[Int]] = [167]scala.None;
     [175]{
-      [175]case <synthetic> val x1: [175]Any = [175]"";
+      [175]case <synthetic> val x1: [175]String = [175]"";
       [175]case5()[195]{
         [195]<synthetic> val o7: [195]Option[List[Int]] = [195][195]Case4.unapplySeq([195]x1);
         [195]if ([195][195]o7.isEmpty.unary_!.&&([195][195][195][195]o7.get.!=([195]null).&&([195][195][195][195]o7.get.lengthCompare([195]1).==([195]0))))
@@ -53,7 +53,7 @@
     };
     [238]def unapply([246]z: [249]<type: [249]scala.Any>): [238]Boolean = [265]true;
     [273]{
-      [273]case <synthetic> val x1: [273]Any = [273]"";
+      [273]case <synthetic> val x1: [273]String = [273]"";
       [273]case5()[293]{
         [293]<synthetic> val o7: [293]Option[List[Int]] = [293][293]Case4.unapplySeq([293]x1);
         [293]if ([293][293]o7.isEmpty.unary_!.&&([293][293][293][293]o7.get.!=([293]null).&&([293][293][293][293]o7.get.lengthCompare([293]0).==([293]0))))