added test case for #3736

tests/ccgbugs/tunsafeaddr.nim

@@ -16,4 +16,13 @@ proc main =
   let foo = [8, 3, 1]
   echo sum(unsafeAddr foo[0], foo.len)
 
+
+# bug #3736
+
+proc p(x: seq[int]) = discard x[0].unsafeAddr # works
+proc q(x: seq[SomeInteger]) = discard x[0].unsafeAddr # doesn't work
+
+p(@[1])
+q(@[1])
+
 main()