Test recategorization

1 files changed, 40 insertions, 0 deletions

diff --git a/tests/neg/t7239.scala b/tests/neg/t7239.scala
new file mode 100644
index 000000000..f3a379b4e
--- /dev/null
+++ b/tests/neg/t7239.scala
@@ -0,0 +1,40 @@
+// Dotty rewrites only withFilter calls occurring in for expressions to filter calls.
+// So this test does not compile.
+object Test {
+  def BrokenMethod(): HasFilter[(Int, String)] = ???
+
+  trait HasFilter[B] {
+    def filter(p: B => Boolean) = ???
+  }
+
+  trait HasWithFilter {
+    def withFilter = ???
+  }
+
+  object addWithFilter {
+    trait NoImplicit
+    implicit def enrich(v: Any)
+                       (implicit F0: NoImplicit): HasWithFilter = ???
+  }
+
+  BrokenMethod().withFilter(_ => true) // error
+  BrokenMethod().filter(_ => true)     // ok
+
+  locally {
+    import addWithFilter._
+    BrokenMethod().withFilter((_: (Int, String)) => true) // error
+  }
+
+  locally {
+    import addWithFilter._
+    // adaptToMemberWithArgs sets the type of the tree `x`
+    // to ErrorType (while in silent mode, so the error is not
+    // reported. Later, when the fallback from `withFilter`
+    // to `filter` is attempted, the closure is taken to have
+    // have the type `<error> => Boolean`, which conforms to
+    // `(B => Boolean)`. Only later during pickling does the
+    // defensive check for erroneous types in the tree pick up
+    // the problem.
+    BrokenMethod().withFilter(x => true) // error
+  }
+}