Merge pull request #1364 from dotty-staging/exhaustivity2

Implementation of exhaustivity and redundancy check

1 files changed, 26 insertions, 0 deletions

diff --git a/tests/patmat/exhaustive_heuristics.scala b/tests/patmat/exhaustive_heuristics.scala
new file mode 100644
index 000000000..7d682f6aa
--- /dev/null
+++ b/tests/patmat/exhaustive_heuristics.scala
@@ -0,0 +1,26 @@
+// tests exhaustivity doesn't give warnings (due to its heuristic rewrites kicking in or it backing off)
+object Test {
+  // List() => Nil
+  List(1) match {
+    case List() =>
+    case x :: xs =>
+  }
+
+  // we don't look into guards
+  val turnOffChecks = true
+  List(1) match {
+    case _ if turnOffChecks =>
+  }
+
+  // we back off when there are any user-defined extractors
+  // in fact this is exhaustive, but we pretend we don't know since List's unapplySeq is not special to the compiler
+  // to compensate our ignorance, we back off
+  // well, in truth, we do rewrite List() to Nil, but otherwise we do nothing
+  // the full rewrite List(a, b) to a :: b :: Nil, for example is planned (but not sure it's a good idea)
+  List(true, false) match {
+    case List(_, _, _:_*) =>
+    case List(node, _:_*)  =>
+    case Nil =>
+  }
+
+}
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