SI-8786 fix generic signature for @varargs forwarder methods

When generating a varargs forwarder for

    def foo[T](a: T*)

the parameter type of the forwarder needs to be Array[Object]. If we
gnerate Array[T] in UnCurry, that would be erased to plain Object, and
the method would not be a valid varargs.

Unfortunately, setting the parameter type to Array[Object] lead to
an invalid generic signature - the generic signature should reflect the
real signature.

This change adds an attachment to the parameter symbol in the varargs
forwarder method and special-cases signature generation.

Also cleanes up the code to produce the varargs forwarder. For example,
type parameter and parameter symbols in the forwarder's method type were
not clones, but the same symbols from the original method were re-used.

3 files changed, 12 insertions, 39 deletions

diff --git a/test/files/jvm/varargs/JavaClass.java b/test/files/jvm/varargs/JavaClass.java
index 6928ee5adc..0cc3587c5e 100644
--- a/test/files/jvm/varargs/JavaClass.java
+++ b/test/files/jvm/varargs/JavaClass.java
@@ -1,16 +1,12 @@
-
-
-
 public class JavaClass {
-    public static <T> void varargz(int i, T... v) {
-    }
-
-    public static void callSomeAnnotations() {
-	VaClass va = new VaClass();
-	va.vs(4, "", "", "");
-	va.vi(1, 2, 3, 4);
-        varargz(5, 1.0, 2.0, 3.0);
-	va.vt(16, "", "", "");
-	System.out.println(va.vt1(16, "a", "b", "c"));
-    }
-}
\ No newline at end of file
+  public static <T> void varargz(int i, T... v) { }
+
+  public static void callSomeAnnotations() {
+      VaClass va = new VaClass();
+      va.vs(4, "", "", "");
+      va.vi(1, 2, 3, 4);
+      varargz(5, 1.0, 2.0, 3.0);
+      va.vt(16, "", "", "");
+      System.out.println(va.vt1(16, "a", "b", "c"));
+  }
+}
diff --git a/test/files/jvm/varargs/VaClass.scala b/test/files/jvm/varargs/VaClass.scala
index d83e63ace1..ee8c288a16 100644
--- a/test/files/jvm/varargs/VaClass.scala
+++ b/test/files/jvm/varargs/VaClass.scala
@@ -1,15 +1,8 @@
-
-
 import annotation.varargs
 
-
-
 class VaClass {
-
   @varargs def vs(a: Int, b: String*) = println(a + b.length)
   @varargs def vi(a: Int, b: Int*) = println(a + b.sum)
   @varargs def vt[T](a: Int, b: T*) = println(a + b.length)
-
-  // TODO remove type bound after fixing SI-8786, see also https://github.com/scala/scala/pull/3961
-  @varargs def vt1[T <: String](a: Int, b: T*): T = b.head
+  @varargs def vt1[T](a: Int, b: T*): T = b.head
 }
diff --git a/test/files/jvm/varargs/varargs.scala b/test/files/jvm/varargs/varargs.scala
index 6d2e707bdf..b09818f46f 100644
--- a/test/files/jvm/varargs/varargs.scala
+++ b/test/files/jvm/varargs/varargs.scala
@@ -1,21 +1,5 @@
-
-
-
-
-
-
 object Test {
   def main(args: Array[String]) {
     JavaClass.callSomeAnnotations
   }
 }
-
-
-
-
-
-
-
-
-
-