Fix for typing of objects in patterns.

An object in a pattern should have type "Foo.type" just as
objects not in patterns do.  Closes SI-5406.  Review by @moors.

4 files changed, 13 insertions, 4 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
index ea8112f1a4..0a1a385846 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -614,7 +614,12 @@ trait Typers extends Modes with Adaptations with PatMatVirtualiser {
 
       if (tree.isErrorTyped) tree
       else if ((mode & (PATTERNmode | FUNmode)) == PATTERNmode && tree.isTerm) { // (1)
-        if (sym.isValue) checkStable(tree)
+        if (sym.isValue) {
+          val tree1 = checkStable(tree)
+          // A module reference in a pattern has type Foo.type, not "object Foo"
+          if (sym.isModule && !sym.isMethod) tree1 setType singleType(pre, sym)
+          else tree1
+        }
         else fail()
       } else if ((mode & (EXPRmode | QUALmode)) == EXPRmode && !sym.isValue && !phase.erasedTypes) { // (2)
         fail()
diff --git a/test/files/neg/t414.check b/test/files/neg/t414.check
index a855497648..d0d24baa33 100644
--- a/test/files/neg/t414.check
+++ b/test/files/neg/t414.check
@@ -1,5 +1,5 @@
 t414.scala:5: error: pattern type is incompatible with expected type;
- found   : object Empty
+ found   : Empty.type (with underlying type object Empty)
  required: IntMap[a]
 Note: if you intended to match against the class, try `case _: Empty[_]` or `case Empty()`
                 case Empty =>
diff --git a/test/files/neg/t4879.check b/test/files/neg/t4879.check
index 49f3c73cf7..94758c751c 100644
--- a/test/files/neg/t4879.check
+++ b/test/files/neg/t4879.check
@@ -1,11 +1,11 @@
 t4879.scala:6: error: pattern type is incompatible with expected type;
- found   : object C
+ found   : C.type (with underlying type object C)
  required: C
 Note: if you intended to match against the class, try `case _: C` or `case C(_)`
     case C  => true
          ^
 t4879.scala:10: error: pattern type is incompatible with expected type;
- found   : object D
+ found   : D.type (with underlying type object D)
  required: D[T,U,V]
 Note: if you intended to match against the class, try `case _: D[_,_,_]` or `case D(_,_,_)`
     case D  => true
diff --git a/test/files/pos/t5406.scala b/test/files/pos/t5406.scala
new file mode 100644
index 0000000000..c2e42c0ac3
--- /dev/null
+++ b/test/files/pos/t5406.scala
@@ -0,0 +1,4 @@
+object Wuffles { }
+object Test {
+  def f = (Some(Wuffles): Option[Wuffles.type]) match { case Some(Wuffles) => println("Woof"); case _ => println("Meow") }
+}