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

2 files changed, 35 insertions, 0 deletions

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))
+}