Fix #2000: Make implicit and non-implicit functions incomparable with <:<

Implicit and non-implicit functions are incomparable with <:<, but are
treated as equivalent with `matches`. This means implicit and non-implicit
functions of the same types override each other, but RefChecks will
give an error because their types are not subtypes.

Also contains a test for #2002.

2 files changed, 27 insertions, 0 deletions

diff --git a/tests/neg/customArgs/i2002.scala b/tests/neg/customArgs/i2002.scala
new file mode 100644
index 000000000..5561b77b8
--- /dev/null
+++ b/tests/neg/customArgs/i2002.scala
@@ -0,0 +1,4 @@
+class Test {
+  def foo(i: Int): Int = i
+  def foo(implicit i: Int): Int = i // error
+}
diff --git a/tests/neg/i2000.scala b/tests/neg/i2000.scala
new file mode 100644
index 000000000..aa1250f08
--- /dev/null
+++ b/tests/neg/i2000.scala
@@ -0,0 +1,23 @@
+object test1 {
+  class C[A] { def foo(a: A) = "c" }
+  class D extends C[String] { override def foo(implicit s: String) = "d" } // error
+}
+
+object test2 {
+  class C[A] { final def foo(a: A) = "c" }
+  class D extends C[String] { def foo(implicit s: String) = "d" } // error
+  object Test {
+    def main(args: Array[String]) =
+      new D
+  }
+}
+
+object test3 {
+  class A {
+    def foo(implicit i: Int): Int = i + i
+  }
+
+  class B extends A {
+    override def foo(i: Int): Int = i // error
+  }
+}