Test #9085.

(cherry picked from commit f5026170)

testsuite/tests/indexed-types/should_compile/T9085.hs

+{-# LANGUAGE TypeFamilies #-}
+
+module T9085 where
+
+type family F a where
+  F a = Int
+  F Bool = Bool

testsuite/tests/indexed-types/should_compile/T9085.stderr

+
+T9085.hs:7:3: Warning:
+    Overlapped type family instance equation:
+      F Bool = Bool

testsuite/tests/indexed-types/should_compile/all.T

@@ -243,3 +243,4 @@ test('T8889', normal, compile, [''])
 test('T8913', normal, compile, [''])
 test('T8978', normal, compile, [''])
 test('T8979', normal, compile, [''])
+test('T9085', normal, compile, [''])