From 1356788ea8c61341a2865d1f31281b7f006d0ce3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Ho=C5=99e=C5=88ovsk=C3=BD?=
 <martin.horenovsky@gmail.com>
Date: Thu, 21 May 2020 21:39:19 +0200
Subject: [PATCH] Avoid using std::result_of when std::invoke_result is
 available

---
 src/catch2/benchmark/detail/catch_complete_invoke.hpp |  9 ++++-----
 src/catch2/benchmark/detail/catch_measure.hpp         |  2 +-
 .../benchmark/detail/catch_run_for_at_least.hpp       |  6 +++---
 src/catch2/benchmark/detail/catch_timing.hpp          |  4 ++--
 src/catch2/internal/catch_meta.hpp                    | 11 +++++------
 5 files changed, 15 insertions(+), 17 deletions(-)

diff --git a/src/catch2/benchmark/detail/catch_complete_invoke.hpp b/src/catch2/benchmark/detail/catch_complete_invoke.hpp
index d6dc2e9d..93b2e2a6 100644
--- a/src/catch2/benchmark/detail/catch_complete_invoke.hpp
+++ b/src/catch2/benchmark/detail/catch_complete_invoke.hpp
@@ -12,6 +12,7 @@
 #define TWOBLUECUBES_CATCH_DETAIL_COMPLETE_INVOKE_HPP_INCLUDED
 
 #include <catch2/internal/catch_enforce.hpp>
+#include <catch2/internal/catch_meta.hpp>
 #include <catch2/interfaces/catch_interfaces_capture.hpp>
 #include <catch2/interfaces/catch_interfaces_registry_hub.hpp>
 
@@ -44,20 +45,18 @@ namespace Catch {
                     return {};
                 }
             };
-            template <typename Sig>
-            using ResultOf_t = typename std::result_of<Sig>::type;
 
             // invoke and not return void :(
             template <typename Fun, typename... Args>
-            CompleteType_t<ResultOf_t<Fun(Args...)>> complete_invoke(Fun&& fun, Args&&... args) {
-                return CompleteInvoker<ResultOf_t<Fun(Args...)>>::invoke(std::forward<Fun>(fun), std::forward<Args>(args)...);
+            CompleteType_t<FunctionReturnType<Fun, Args...>> complete_invoke(Fun&& fun, Args&&... args) {
+                return CompleteInvoker<FunctionReturnType<Fun, Args...>>::invoke(std::forward<Fun>(fun), std::forward<Args>(args)...);
             }
 
             extern const std::string benchmarkErrorMsg;
         } // namespace Detail
 
         template <typename Fun>
-        Detail::CompleteType_t<Detail::ResultOf_t<Fun()>> user_code(Fun&& fun) {
+        Detail::CompleteType_t<FunctionReturnType<Fun>> user_code(Fun&& fun) {
             CATCH_TRY{
                 return Detail::complete_invoke(std::forward<Fun>(fun));
             } CATCH_CATCH_ALL{
diff --git a/src/catch2/benchmark/detail/catch_measure.hpp b/src/catch2/benchmark/detail/catch_measure.hpp
index 9cee9793..686150d1 100644
--- a/src/catch2/benchmark/detail/catch_measure.hpp
+++ b/src/catch2/benchmark/detail/catch_measure.hpp
@@ -21,7 +21,7 @@ namespace Catch {
     namespace Benchmark {
         namespace Detail {
             template <typename Clock, typename Fun, typename... Args>
-            TimingOf<Clock, Fun(Args...)> measure(Fun&& fun, Args&&... args) {
+            TimingOf<Clock, Fun, Args...> measure(Fun&& fun, Args&&... args) {
                 auto start = Clock::now();
                 auto&& r = Detail::complete_invoke(fun, std::forward<Args>(args)...);
                 auto end = Clock::now();
diff --git a/src/catch2/benchmark/detail/catch_run_for_at_least.hpp b/src/catch2/benchmark/detail/catch_run_for_at_least.hpp
index ee5510d6..5efc539c 100644
--- a/src/catch2/benchmark/detail/catch_run_for_at_least.hpp
+++ b/src/catch2/benchmark/detail/catch_run_for_at_least.hpp
@@ -25,11 +25,11 @@ namespace Catch {
     namespace Benchmark {
         namespace Detail {
             template <typename Clock, typename Fun>
-            TimingOf<Clock, Fun(int)> measure_one(Fun&& fun, int iters, std::false_type) {
+            TimingOf<Clock, Fun, int> measure_one(Fun&& fun, int iters, std::false_type) {
                 return Detail::measure<Clock>(fun, iters);
             }
             template <typename Clock, typename Fun>
-            TimingOf<Clock, Fun(Chronometer)> measure_one(Fun&& fun, int iters, std::true_type) {
+            TimingOf<Clock, Fun, Chronometer> measure_one(Fun&& fun, int iters, std::true_type) {
                 Detail::ChronometerModel<Clock> meter;
                 auto&& result = Detail::complete_invoke(fun, Chronometer(meter, iters));
 
@@ -44,7 +44,7 @@ namespace Catch {
             void throw_optimized_away_error();
 
             template <typename Clock, typename Fun>
-            TimingOf<Clock, Fun(run_for_at_least_argument_t<Clock, Fun>)> run_for_at_least(ClockDuration<Clock> how_long, int seed, Fun&& fun) {
+            TimingOf<Clock, Fun, run_for_at_least_argument_t<Clock, Fun>> run_for_at_least(ClockDuration<Clock> how_long, int seed, Fun&& fun) {
                 auto iters = seed;
                 while (iters < (1 << 30)) {
                     auto&& Timing = measure_one<Clock>(fun, iters, is_callable<Fun(Chronometer)>());
diff --git a/src/catch2/benchmark/detail/catch_timing.hpp b/src/catch2/benchmark/detail/catch_timing.hpp
index 1844422e..36e7d18d 100644
--- a/src/catch2/benchmark/detail/catch_timing.hpp
+++ b/src/catch2/benchmark/detail/catch_timing.hpp
@@ -24,8 +24,8 @@ namespace Catch {
             Result result;
             int iterations;
         };
-        template <typename Clock, typename Sig>
-        using TimingOf = Timing<ClockDuration<Clock>, Detail::CompleteType_t<Detail::ResultOf_t<Sig>>>;
+        template <typename Clock, typename Func, typename... Args>
+        using TimingOf = Timing<ClockDuration<Clock>, Detail::CompleteType_t<FunctionReturnType<Func, Args...>>>;
     } // namespace Benchmark
 } // namespace Catch
 
diff --git a/src/catch2/internal/catch_meta.hpp b/src/catch2/internal/catch_meta.hpp
index 56cfa0a9..d1455e35 100644
--- a/src/catch2/internal/catch_meta.hpp
+++ b/src/catch2/internal/catch_meta.hpp
@@ -32,13 +32,12 @@ namespace Catch {
 
 #if defined(__cpp_lib_is_invocable) && __cpp_lib_is_invocable >= 201703
     // std::result_of is deprecated in C++17 and removed in C++20. Hence, it is
-    // replaced with std::invoke_result here. Also *_t format is preferred over
-    // typename *::type format.
-    template <typename Func, typename U>
-    using FunctionReturnType = std::remove_reference_t<std::remove_cv_t<std::invoke_result_t<Func, U>>>;
+    // replaced with std::invoke_result here.
+    template <typename Func, typename... U>
+    using FunctionReturnType = std::remove_reference_t<std::remove_cv_t<std::invoke_result_t<Func, U...>>>;
 #else
-    template <typename Func, typename U>
-    using FunctionReturnType = std::remove_reference_t<std::remove_cv_t<std::result_of_t<Func(U)>>>;
+    template <typename Func, typename... U>
+    using FunctionReturnType = std::remove_reference_t<std::remove_cv_t<std::result_of_t<Func(U...)>>>;
 #endif
 
 } // namespace Catch