SI-7296 Remove arity limit for case classes

When venturing above the pre-ordained limit of twenty
two, `Companion extends FunctionN` and `Companion.unapply`
are sacrificed. But oh-so-many other case class features
work perfectly: equality/hashing/stringification, the apply
method, and even pattern matching (which already bypasses
unapply.)

There was some understandable fear of the piecemeal when
I tabled this idea on scala-internals [1]. But I'd like
to persist as this limit is a needless source of pain for
anyone using case classes to bind to database, XML or JSON
schemata.

[1] https://groups.google.com/forum/#!topic/scala-internals/RRu5bppi16Y

6 files changed, 35 insertions, 8 deletions

diff --git a/test/files/neg/t3631.check b/test/files/neg/t3631.check
deleted file mode 100644
index 6d8feca1ed..0000000000
--- a/test/files/neg/t3631.check
+++ /dev/null
@@ -1,4 +0,0 @@
-t3631.scala:3: error: Implementation restriction: case classes cannot have more than 22 parameters.
-case class X23(x1: Int, x2: Int, x3: Int, x4: Int, x5: Int, x6: Int, x7: Int, x8: Int, x9: Int, x10: Int, x11: Int, x12: Int, x13: Int, x14: Int, x15: Int, x16: Int, x17: Int, x18: Int, x19: Int, x20: Int, x21: Int, x22: Int, x23: Int) { }
-           ^
-one error found
diff --git a/test/files/neg/t7296.check b/test/files/neg/t7296.check
deleted file mode 100644
index 66e8353ee3..0000000000
--- a/test/files/neg/t7296.check
+++ /dev/null
@@ -1,4 +0,0 @@
-t7296.scala:5: error: Implementation restriction: case classes cannot have more than 22 parameters.
-  case class Foo(a: A, b: A, c: A, d: A, e: A, f: A, g: A, h: A, i: A, j: A, k: A, l: A, m: A, n: A, o: A, p: A, q: A, r: A, s: A, t: A, u: A, v: A, w: A, x: A, y: A, Z: A)
-             ^
-one error found
diff --git a/test/files/neg/t3631.scala b/test/files/pos/t3631.scala
index bcf91619ee..bcf91619ee 100644
--- a/test/files/neg/t3631.scala
+++ b/test/files/pos/t3631.scala
diff --git a/test/files/neg/t7296.scala b/test/files/pos/t7296.scala
index 0c078d3657..0c078d3657 100644
--- a/test/files/neg/t7296.scala
+++ b/test/files/pos/t7296.scala
diff --git a/test/files/run/case-class-23.check b/test/files/run/case-class-23.check
new file mode 100644
index 0000000000..888ed2c9eb
--- /dev/null
+++ b/test/files/run/case-class-23.check
@@ -0,0 +1,2 @@
+23
+(1,23)
diff --git a/test/files/run/case-class-23.scala b/test/files/run/case-class-23.scala
new file mode 100644
index 0000000000..92b719574a
--- /dev/null
+++ b/test/files/run/case-class-23.scala
@@ -0,0 +1,33 @@
+case class TwentyThree(
+  _1: Int,
+  _2: Int,
+  _3: Int,
+  _4: Int,
+  _5: Int,
+  _6: Int,
+  _7: Int,
+  _8: Int,
+  _9: Int,
+  _10: Int,
+  _11: Int,
+  _12: Int,
+  _13: Int,
+  _14: Int,
+  _15: Int,
+  _16: Int,
+  _17: Int,
+  _18: Int,
+  _19: Int,
+  _20: Int,
+  _21: Int,
+  _22: Int,
+  _23: Int
+)
+
+object Test extends App {
+  val x = new TwentyThree(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
+  println(x._23)
+  assert(x.copy(_1 = 1) == x)
+  val TwentyThree(a, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, b) = x
+  println((a, b))
+}