Harden typedUnapply

Author: odersky

compiler/src/dotty/tools/dotc/typer/Applications.scala

@@ -967,6 +967,7 @@ trait Applications extends Compatibility { self: Typer with Dynamic =>
           case Apply(Apply(unapply, `dummyArg` :: Nil), args2) => assert(args2.nonEmpty); args2
           case Apply(unapply, `dummyArg` :: Nil) => Nil
           case Inlined(u, _, _) => unapplyImplicits(u)
+          case _ => assert(ctx.reporter.errorsReported); Nil
         }
 
         var argTypes = unapplyArgs(unapplyApp.tpe, unapplyFn, args, tree.pos)

tests/neg/parser-stability-10.scala

@@ -0,0 +1,13 @@
+object i0 {
+def unapply(i1: Int)(i6: List[Int]): Int = {
+  def i7(i8: i0) = i1 match {  // error
+    case i0(_) =>              // error
+      (i1, i8) match {
+        case i0(i1, i1) => case _ => i2  // error // error
+      }
+  }
+}  // error
+object i5 {
+  import collection.mutable._
+  try { ??? mutable { case i1(i5, i3, i4) => i5 }}  // error
+}  // error