SI-8989 Better error message for invalid extractor pattern

5 files changed, 51 insertions, 5 deletions

diff --git a/test/files/neg/t4425b.check b/test/files/neg/t4425b.check
index 8418b4fd12..a204467586 100644
--- a/test/files/neg/t4425b.check
+++ b/test/files/neg/t4425b.check
@@ -22,16 +22,28 @@ t4425b.scala:10: error: object X is not a case class, nor does it have an unappl
 Note: def unapply(x: String)(y: String): Nothing exists in object X, but it cannot be used as an extractor due to its second non-implicit parameter list
     println((X: Any) match { case X(_, _) => "ok" ; case _ => "fail" })
                                   ^
-t4425b.scala:18: error: too many patterns for object X: expected 1, found 2
+t4425b.scala:18: error: The result type of an unapply method must contain a member `get` to be used as an extractor pattern, no such member exists in Nothing
+    println(      "" match { case _ X _   => "ok" ; case _ => "fail" })
+                                  ^
+t4425b.scala:18: error: too many patterns for object X offering Boolean: expected 0, found 2
     println(      "" match { case _ X _   => "ok" ; case _ => "fail" })
                                     ^
-t4425b.scala:19: error: too many patterns for object X: expected 1, found 2
+t4425b.scala:19: error: The result type of an unapply method must contain a member `get` to be used as an extractor pattern, no such member exists in Nothing
+    println((X: Any) match { case _ X _   => "ok" ; case _ => "fail" })
+                                  ^
+t4425b.scala:19: error: too many patterns for object X offering Boolean: expected 0, found 2
     println((X: Any) match { case _ X _   => "ok" ; case _ => "fail" })
                                     ^
-t4425b.scala:22: error: too many patterns for object X: expected 1, found 2
+t4425b.scala:20: error: The result type of an unapply method must contain a member `get` to be used as an extractor pattern, no such member exists in Nothing
+    println(      "" match { case X(_)    => "ok" ; case _ => "fail" })
+                                  ^
+t4425b.scala:21: error: The result type of an unapply method must contain a member `get` to be used as an extractor pattern, no such member exists in Nothing
+    println((X: Any) match { case X(_)    => "ok" ; case _ => "fail" })
+                                  ^
+t4425b.scala:22: error: The result type of an unapply method must contain a member `get` to be used as an extractor pattern, no such member exists in Nothing
     println(      "" match { case X(_, _) => "ok" ; case _ => "fail" })
                                   ^
-t4425b.scala:23: error: too many patterns for object X: expected 1, found 2
+t4425b.scala:23: error: The result type of an unapply method must contain a member `get` to be used as an extractor pattern, no such member exists in Nothing
     println((X: Any) match { case X(_, _) => "ok" ; case _ => "fail" })
                                   ^
 t4425b.scala:31: error: too many patterns for object X offering Nothing: expected 1, found 2
@@ -46,4 +58,4 @@ t4425b.scala:35: error: too many patterns for object X offering Nothing: expecte
 t4425b.scala:36: error: too many patterns for object X offering Nothing: expected 1, found 2
     println((X: Any) match { case X(_, _) => "ok" ; case _ => "fail" })
                                   ^
-14 errors found
+18 errors found
diff --git a/test/files/neg/t8127a.check b/test/files/neg/t8127a.check
new file mode 100644
index 0000000000..5a30574861
--- /dev/null
+++ b/test/files/neg/t8127a.check
@@ -0,0 +1,4 @@
+t8127a.scala:7: error: The result type of an unapplySeq method must contain a member `get` to be used as an extractor pattern, no such member exists in Seq[_$1]
+    case H(v) =>
+         ^
+one error found
diff --git a/test/files/neg/t8127a.scala b/test/files/neg/t8127a.scala
new file mode 100644
index 0000000000..c05facdac1
--- /dev/null
+++ b/test/files/neg/t8127a.scala
@@ -0,0 +1,12 @@
+object H {
+  def unapplySeq(m: Any): Seq[_] = List("")
+}
+
+object Test {
+  def unapply(m: Any) = m match {
+    case H(v) =>
+    case _ =>
+  }
+  // now:  too many patterns for object H offering Boolean: expected 0, found 1
+  // was: result type Seq[_$2] of unapplySeq defined in method unapplySeq in object H does not conform to Option[_]
+}
diff --git a/test/files/neg/t8989.check b/test/files/neg/t8989.check
new file mode 100644
index 0000000000..4e89b862bd
--- /dev/null
+++ b/test/files/neg/t8989.check
@@ -0,0 +1,4 @@
+t8989.scala:11: error: The result type of an unapply method must contain a member `get` to be used as an extractor pattern, no such member exists in A
+  val f = p match {case d(1) => true; case _ => false}
+                        ^
+one error found
diff --git a/test/files/neg/t8989.scala b/test/files/neg/t8989.scala
new file mode 100644
index 0000000000..8ed6a901cd
--- /dev/null
+++ b/test/files/neg/t8989.scala
@@ -0,0 +1,14 @@
+class A extends Product1[Int] {
+    def _1 = 1
+    def isEmpty = false // used by scalac
+    def isDefined = !isEmpty // used by dotty
+    def canEqual(a: Any) = true
+}
+
+object d{
+  def unapply(a: Any) = new A
+  val p: Any = ???
+  val f = p match {case d(1) => true; case _ => false}
+}
+
+