From 69f7d63a7aa1e04dd77b281bffb5f2a3a3889a26 Mon Sep 17 00:00:00 2001
From: Matt Witherspoon <32485495+spoonincode@users.noreply.github.com>
Date: Thu, 10 Jun 2021 16:50:02 -0400
Subject: [PATCH] replace is_callable_v workaround with is_invocable_v

---
 include/eosio/vm/function_traits.hpp | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/include/eosio/vm/function_traits.hpp b/include/eosio/vm/function_traits.hpp
index 76a88181..2355643b 100644
--- a/include/eosio/vm/function_traits.hpp
+++ b/include/eosio/vm/function_traits.hpp
@@ -72,12 +72,6 @@ namespace eosio { namespace vm {
       inline constexpr U&& make_dependent(U&& u) { return static_cast<U&&>(u); }
    }
 
-   template <auto FN>
-   inline constexpr static bool is_callable_v = EOS_VM_HAS_MEMBER(AUTO_PARAM_WORKAROUND(FN), operator());
-
-   template <typename F>
-   constexpr bool is_callable(F&& fn) { return EOS_VM_HAS_MEMBER(fn, operator()); }
-
    namespace detail {
       template <bool Decay, typename R, typename... Args>
       constexpr auto get_types(R(Args...)) -> std::tuple<R, freestanding,
@@ -102,7 +96,7 @@ namespace eosio { namespace vm {
                                                                std::tuple<std::conditional_t<Decay, std::decay_t<Args>, Args>...>>;
       template <bool Decay, typename F>
       constexpr auto get_types(F&& fn) {
-         if constexpr (is_callable_v<decltype(fn)>)
+         if constexpr (std::is_invocable_v<decltype(fn)>)
             return get_types<Decay>(&F::operator());
          else
             return get_types<Decay>(fn);
@@ -144,7 +138,7 @@ namespace eosio { namespace vm {
       constexpr auto parameters_from_impl(R(Cls::*)(Args...)const &&) ->  pack_from_t<N, Args...>;
       template <std::size_t N, typename F>
       constexpr auto parameters_from_impl(F&& fn) {
-         if constexpr (is_callable_v<decltype(fn)>)
+         if constexpr (std::is_invocable_v<decltype(fn)>)
             return parameters_from_impl<N>(&F::operator());
          else
             return parameters_from_impl<N>(fn);