SI-7932 Exclude PolyTypes from Java generic signatures

In the enclosed test case, we were emitting just the result type of
`[a, b]Float` in the Java generic signature.

This resulted in a `GenericSignatureFormatError`.

This commit changes `argSig` to project such type functions to `*`
instead.

The test case shows that we still emit the class when we use
its type constructor directly as the type argument.

1 files changed, 11 insertions, 0 deletions

diff --git a/test/files/run/t7932.scala b/test/files/run/t7932.scala
new file mode 100644
index 0000000000..8743abff88
--- /dev/null
+++ b/test/files/run/t7932.scala
@@ -0,0 +1,11 @@
+class Category[M[_, _]]
+trait M[F] {
+  type X[a, b] = F
+  def category: Category[X] = null
+  def category1: Category[Tuple2] = null
+}
+abstract class C extends M[Float]
+object Test extends App {
+  val ms = classOf[C].getMethods.filter(_.getName.startsWith("category"))
+  println(ms.map(_.toGenericString).sorted.mkString("\n"))
+}