From 483c845c078413b73ebb0b7e03b1c8c142bacac9 Mon Sep 17 00:00:00 2001
From: liu fengyun <liu@fengy.me>
Date: Thu, 23 Nov 2017 17:26:00 +0100
Subject: [PATCH 1/2] Fix #3543: compare extractor with TermRef instead of
 MethodType

---
 .../tools/dotc/transform/patmat/Space.scala   |  4 +-
 tests/patmat/3543.scala                       | 52 +++++++++++++++++++
 2 files changed, 54 insertions(+), 2 deletions(-)
 create mode 100644 tests/patmat/3543.scala

diff --git a/compiler/src/dotty/tools/dotc/transform/patmat/Space.scala b/compiler/src/dotty/tools/dotc/transform/patmat/Space.scala
index 3f9f7d3143af..bce2752d7164 100644
--- a/compiler/src/dotty/tools/dotc/transform/patmat/Space.scala
+++ b/compiler/src/dotty/tools/dotc/transform/patmat/Space.scala
@@ -400,9 +400,9 @@ class SpaceEngine(implicit ctx: Context) extends SpaceLogic {
         if (fun.symbol.owner == scalaSeqFactoryClass)
           projectSeq(pats)
         else
-          Prod(pat.tpe.stripAnnots, fun.tpe.widen, fun.symbol, projectSeq(pats) :: Nil, irrefutable(fun))
+          Prod(pat.tpe.stripAnnots, fun.tpe, fun.symbol, projectSeq(pats) :: Nil, irrefutable(fun))
       else
-        Prod(pat.tpe.stripAnnots, fun.tpe.widen, fun.symbol, pats.map(project), irrefutable(fun))
+        Prod(pat.tpe.stripAnnots, fun.tpe, fun.symbol, pats.map(project), irrefutable(fun))
     case Typed(pat @ UnApply(_, _, _), _) => project(pat)
     case Typed(expr, tpt) =>
       Typ(erase(expr.tpe.stripAnnots), true)
diff --git a/tests/patmat/3543.scala b/tests/patmat/3543.scala
new file mode 100644
index 000000000000..ce93b01c1840
--- /dev/null
+++ b/tests/patmat/3543.scala
@@ -0,0 +1,52 @@
+class Test {
+  class Foo {
+    def unapply(x: String): Option[String] = ???
+  }
+
+  def test(xs: List[String]): Unit = {
+    val Yes = new Foo
+    val No = new Foo
+
+    xs match {
+      case Yes(x) :: ls => println("Yes")
+      case No(y) :: ls => println("No") // unreachable code
+      case _ =>
+    }
+  }
+}
+
+class Test2 {
+  class Foo(x: Boolean) {
+    def unapply(y: String): Boolean = x
+  }
+
+  def test(xs: List[String]): Unit = {
+    val Yes = new Foo(true)
+    val No = new Foo(false)
+
+    xs match {
+      case No() :: ls => println("No")
+      case Yes() :: ls => println("Yes") // unreachable code
+      case _ =>
+    }
+  }
+}
+
+class Test3 {
+  import scala.util.matching.Regex
+
+  def main(args: Array[String]): Unit = {
+    foo("c" :: Nil, false)
+  }
+
+  def foo(remaining: List[String], inCodeBlock: Boolean): Unit = {
+    remaining match {
+      case CodeBlockEndRegex(before) :: ls =>
+      case SymbolTagRegex(name) :: ls if !inCodeBlock => println("OK")
+      case _ =>
+    }
+  }
+
+  val CodeBlockEndRegex = new Regex("(b)")
+  val SymbolTagRegex = new Regex("(c)")
+}

From e41b2bacdc4446bc5cadcc31c2923c00e20df38d Mon Sep 17 00:00:00 2001
From: Fengyun Liu <liu@fengy.me>
Date: Thu, 23 Nov 2017 18:21:37 +0100
Subject: [PATCH 2/2] remove obsolete comment

---
 tests/patmat/3543.scala | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tests/patmat/3543.scala b/tests/patmat/3543.scala
index ce93b01c1840..c3659db431e6 100644
--- a/tests/patmat/3543.scala
+++ b/tests/patmat/3543.scala
@@ -9,7 +9,7 @@ class Test {
 
     xs match {
       case Yes(x) :: ls => println("Yes")
-      case No(y) :: ls => println("No") // unreachable code
+      case No(y) :: ls => println("No")
       case _ =>
     }
   }
@@ -26,7 +26,7 @@ class Test2 {
 
     xs match {
       case No() :: ls => println("No")
-      case Yes() :: ls => println("Yes") // unreachable code
+      case Yes() :: ls => println("Yes")
       case _ =>
     }
   }