Remove formattable
diff --git a/include/fmt/core.h b/include/fmt/core.h
index 42e930a..449ed04 100644
--- a/include/fmt/core.h
+++ b/include/fmt/core.h
@@ -1391,8 +1391,6 @@
   return vis(monostate());
 }
 
-template <typename T> struct formattable : std::false_type {};
-
 namespace detail {
 
 #if FMT_GCC_VERSION && FMT_GCC_VERSION < 500