Drop the requirement that extractors with `get` must implement Product

We used to require that the result type of an extractor `get` is a product,
or else the type of the `get` itself would be taken as the result type of the
unapply. This is now relaxed so that we automatically select with _1, _2, ...
as soon as there are multiple argument patterns, and (1) the result type is not
a Seq, (2) the number of consecutive product conselectors matches the number
of arguments.

1 files changed, 32 insertions, 0 deletions

diff --git a/tests/pos/extractors.scala b/tests/pos/extractors.scala
new file mode 100644
index 000000000..8e5b0e9d2
--- /dev/null
+++ b/tests/pos/extractors.scala
@@ -0,0 +1,32 @@
+object test {
+
+  class Tree
+  class Apply(val fun: Tree, val args: List[Tree]) extends Tree
+
+  trait DeconstructorCommon[T >: Null <: AnyRef] {
+    var field: T = null
+    def get: this.type = this
+    def isEmpty: Boolean = field eq null
+    def isDefined = !isEmpty
+    def unapply(s: T): this.type ={
+      field = s
+      this
+    }
+  }
+
+  trait ApplyDeconstructor extends DeconstructorCommon[Apply] {
+    def _1: Tree
+    def _2: List[Tree]
+  }
+
+  object Apply extends ApplyDeconstructor {
+    def _1: Tree = field.fun
+    def _2: List[Tree] = field.args
+  }
+
+  def assocsFromApply(tree: Tree) = {
+    tree match {
+      case Apply(fun, args) => ???
+    }
+  }
+}