handle SeqLiteral in patterns

Author: liufengyun

compiler/src/dotty/tools/dotc/core/Definitions.scala

@@ -77,7 +77,10 @@ class Definitions {
         val cls = denot.asClass.classSymbol
         val paramDecls = newScope
         val typeParam = enterSyntheticTypeParam(cls, paramFlags, paramDecls)
-        val parents = parentConstrs.toList
+        def instantiate(tpe: Type) =
+          if (tpe.typeParams.nonEmpty) tpe.appliedTo(typeParam.typeRef)
+          else tpe
+        val parents = parentConstrs.toList map instantiate
         denot.info = ClassInfo(ScalaPackageClass.thisType, cls, parents, paramDecls)
       }
     }

compiler/src/dotty/tools/dotc/transform/PatternMatcher.scala

@@ -351,6 +351,8 @@ object PatternMatcher {
           }
         case WildcardPattern() =>
           onSuccess
+        case SeqLiteral(pats, _) =>
+          matchElemsPlan(scrutinee, pats, exact = true, onSuccess)
         case _ =>
           TestPlan(EqualTest(tree), scrutinee, tree.pos, onSuccess, onFailure)
       }

compiler/src/dotty/tools/dotc/transform/patmat/Space.scala

@@ -395,6 +395,7 @@ class SpaceEngine(implicit ctx: Context) extends SpaceLogic {
       Typ(pat.tpe.stripAnnots, false)
     case Alternative(trees) => Or(trees.map(project(_)))
     case Bind(_, pat) => project(pat)
+    case SeqLiteral(pats, _) => projectSeq(pats)
     case UnApply(fun, _, pats) =>
       if (fun.symbol.name == nme.unapplySeq)
         if (fun.symbol.owner == scalaSeqFactoryClass)
@@ -496,7 +497,7 @@ class SpaceEngine(implicit ctx: Context) extends SpaceLogic {
 
     debug.println(s"signature of ${unappSym.showFullName} ----> ${sig.map(_.show).mkString(", ")}")
 
-    sig
+    sig.map(_.annotatedToRepeated)
   }
 
   /** Decompose a type into subspaces -- assume the type can be decomposed */

tests/patmat/t8178.scala

@@ -4,7 +4,7 @@ case class FailsChild2(a: Seq[String]) extends Fails
 object FailsTest {
   def matchOnVarArgsFirstFails(f: Fails) = {
     f match {
-      case VarArgs1(_) => ???
+      case VarArgs1(_: _*) => ???
       // BUG: Without this line we should get a non-exhaustive match compiler error.
       //case FailsChild2(_) => ???
     }

tests/run/i3248.scala

@@ -13,6 +13,7 @@ object Test extends App {
 
   def bar(f: Any) = f match {
     case Bar(1, 2, 3) => 0
+    case Bar(a, b) => a + b
     case Bar(ns: _*) => ns.length
   }