Parser relaxation so that one can name the type...

Parser relaxation so that one can name the type variables in a
constructor pattern match: this is a prerequisite to realizing the full
potential of gadts. (Nothing new works here however.) No review.

3 files changed, 24 insertions, 15 deletions

diff --git a/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala b/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala
index 09f1db7249..1ae9a9d8c0 100644
--- a/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala
+++ b/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala
@@ -1633,19 +1633,14 @@ self =>
               }
             case _ =>
           }
-          /* not yet
-           if (in.token == LBRACKET)
-           atPos(in.offset) {
-           val ts = typeArgs(true, false)
-           accept(LPAREN)
-           val ps = if (in.token == RPAREN) List() else patterns(true, false)
-           accept(RPAREN)
-           Apply(TypeApply(convertToTypeId(t), ts), ps)
-           }
-           else */
-          if (in.token == LPAREN)
-            atPos(start, in.offset) { Apply(t, argumentPatterns()) }
-          else t
+          val typeAppliedTree = in.token match {
+            case LBRACKET   => atPos(start, in.offset)(TypeApply(convertToTypeId(t), typeArgs(true, false)))
+            case _          => t
+          }
+          in.token match {
+            case LPAREN   => atPos(start, in.offset)(Apply(typeAppliedTree, argumentPatterns()))
+            case _        => typeAppliedTree
+          }
         case USCORE =>
           in.nextToken()
           atPos(start, start) { Ident(nme.WILDCARD) }
diff --git a/test/files/neg/gadts1.check b/test/files/neg/gadts1.check
index 4c91a3bcf8..44d2b114d6 100644
--- a/test/files/neg/gadts1.check
+++ b/test/files/neg/gadts1.check
@@ -3,4 +3,12 @@ gadts1.scala:15: error: type mismatch;
  required: a
     case NumTerm(n) => c.x = Double(1.0) 
                                    ^
-one error found
+gadts1.scala:20: error: class Cell of type Test.Cell does not take type parameters.
+    case Cell[a](x: Int) => c.x = 5
+             ^
+gadts1.scala:20: error: type mismatch;
+ found   : Int(5)
+ required: a
+    case Cell[a](x: Int) => c.x = 5
+                                  ^
+three errors found
diff --git a/test/files/neg/gadts1.scala b/test/files/neg/gadts1.scala
index 07200ff7aa..08403e6eec 100644
--- a/test/files/neg/gadts1.scala
+++ b/test/files/neg/gadts1.scala
@@ -10,10 +10,16 @@ case class NumTerm(val n: Number) extends Term[Number]
 class IntTerm(n: Int) extends NumTerm(n) with Term[Int]
 
 
-def f[a](t:Term[a], c:Cell[a]): Unit =
+def f[a](t:Term[a], c:Cell[a]): Unit = {
   t match {
     case NumTerm(n) => c.x = Double(1.0)
   }
+  t match {
+    // presently testing that this gets past the parser: eventually
+    // it should actually work.
+    case Cell[a](x: Int) => c.x = 5
+  }
+}
 
 
 val x:Term[Number] = NumTerm(Int(5))