Prefer _t over ::type form for std type traits

src/catch2/benchmark/catch_benchmark.hpp

@@ -93,8 +93,7 @@ namespace Catch {
             }
 
             // sets lambda to be used in fun *and* executes benchmark!
-            template <typename Fun,
-                typename std::enable_if<!Detail::is_related<Fun, Benchmark>::value, int>::type = 0>
+            template <typename Fun, std::enable_if_t<!Detail::is_related<Fun, Benchmark>::value, int> = 0>
                 Benchmark & operator=(Fun func) {
                 fun = Detail::BenchmarkFunction(func);
                 run();

src/catch2/benchmark/catch_constructor.hpp

@@ -20,7 +20,7 @@ namespace Catch {
             template <typename T, bool Destruct>
             struct ObjectStorage
             {
-                using TStorage = typename std::aligned_storage<sizeof(T), std::alignment_of<T>::value>::type;
+                using TStorage = std::aligned_storage_t<sizeof(T), std::alignment_of<T>::value>;
 
                 ObjectStorage() : data() {}
 
@@ -43,7 +43,7 @@ namespace Catch {
                 }
 
                 template <bool AllowManualDestruction = !Destruct>
-                typename std::enable_if<AllowManualDestruction>::type destruct()
+                std::enable_if_t<AllowManualDestruction> destruct()
                 {
                     stored_object().~T();
                 }
@@ -51,10 +51,10 @@ namespace Catch {
             private:
                 // If this is a constructor benchmark, destruct the underlying object
                 template <typename U>
-                void destruct_on_exit(typename std::enable_if<Destruct, U>::type* = 0) { destruct<true>(); }
+                void destruct_on_exit(std::enable_if_t<Destruct, U>* = 0) { destruct<true>(); }
                 // Otherwise, don't
                 template <typename U>
-                void destruct_on_exit(typename std::enable_if<!Destruct, U>::type* = 0) { }
+                void destruct_on_exit(std::enable_if_t<!Destruct, U>* = 0) { }
 
                 T& stored_object() {
                     return *static_cast<T*>(static_cast<void*>(&data));

src/catch2/benchmark/catch_optimizer.hpp

@@ -57,12 +57,12 @@ namespace Catch {
         }
 
         template <typename Fn, typename... Args>
-        inline auto invoke_deoptimized(Fn&& fn, Args&&... args) -> typename std::enable_if<!std::is_same<void, decltype(fn(args...))>::value>::type {
+        inline auto invoke_deoptimized(Fn&& fn, Args&&... args) -> std::enable_if_t<!std::is_same<void, decltype(fn(args...))>::value> {
             deoptimize_value(CATCH_FORWARD(fn) (CATCH_FORWARD(args)...));
         }
 
         template <typename Fn, typename... Args>
-        inline auto invoke_deoptimized(Fn&& fn, Args&&... args) -> typename std::enable_if<std::is_same<void, decltype(fn(args...))>::value>::type {
+        inline auto invoke_deoptimized(Fn&& fn, Args&&... args) -> std::enable_if_t<std::is_same<void, decltype(fn(args...))>::value> {
             CATCH_FORWARD(fn) (CATCH_FORWARD(args)...);
         }
     } // namespace Benchmark

src/catch2/benchmark/detail/catch_benchmark_function.hpp

@@ -22,11 +22,9 @@
 namespace Catch {
     namespace Benchmark {
         namespace Detail {
-            template <typename T>
-            using Decay = typename std::decay<T>::type;
             template <typename T, typename U>
             struct is_related
-                : std::is_same<Decay<T>, Decay<U>> {};
+                : std::is_same<std::decay_t<T>, std::decay_t<U>> {};
 
             /// We need to reinvent std::function because every piece of code that might add overhead
             /// in a measurement context needs to have consistent performance characteristics so that we
@@ -76,9 +74,9 @@ namespace Catch {
                     : f(new model<do_nothing>{ {} }) {}
 
                 template <typename Fun,
-                    typename std::enable_if<!is_related<Fun, BenchmarkFunction>::value, int>::type = 0>
+                    std::enable_if_t<!is_related<Fun, BenchmarkFunction>::value, int> = 0>
                     BenchmarkFunction(Fun&& fun)
-                    : f(new model<typename std::decay<Fun>::type>(CATCH_FORWARD(fun))) {}
+                    : f(new model<std::decay_t<Fun>>(CATCH_FORWARD(fun))) {}
 
                 BenchmarkFunction( BenchmarkFunction&& that ) noexcept:
                     f( CATCH_MOVE( that.f ) ) {}

src/catch2/benchmark/detail/catch_repeat.hpp

@@ -26,7 +26,7 @@ namespace Catch {
                 Fun fun;
             };
             template <typename Fun>
-            repeater<typename std::decay<Fun>::type> repeat(Fun&& fun) {
+            repeater<std::decay_t<Fun>> repeat(Fun&& fun) {
                 return { CATCH_FORWARD(fun) };
             }
         } // namespace Detail

src/catch2/benchmark/detail/catch_run_for_at_least.hpp

@@ -36,7 +36,7 @@ namespace Catch {
             }
 
             template <typename Clock, typename Fun>
-            using run_for_at_least_argument_t = typename std::conditional<is_callable<Fun(Chronometer)>::value, Chronometer, int>::type;
+            using run_for_at_least_argument_t = std::conditional_t<is_callable<Fun(Chronometer)>::value, Chronometer, int>;
 
 
             [[noreturn]]

src/catch2/internal/catch_clara.hpp

@@ -69,8 +69,7 @@ namespace Catch {
             template <typename ClassT, typename ReturnT, typename ArgT>
             struct UnaryLambdaTraits<ReturnT ( ClassT::* )( ArgT ) const> {
                 static const bool isValid = true;
-                using ArgType = typename std::remove_const<
-                    typename std::remove_reference<ArgT>::type>::type;
+                using ArgType = std::remove_const_t<std::remove_reference_t<ArgT>>;
                 using ReturnType = ReturnT;
             };