Replace SFINAE with concepts (#5361)

Concepts are cleaner to use and result in much better error messages for incorrect template use.

wpilibc/src/main/native/include/frc/Notifier.h

@@ -10,11 +10,11 @@
 #include <functional>
 #include <string_view>
 #include <thread>
-#include <type_traits>
 #include <utility>
 
 #include <hal/Types.h>
 #include <units/time.h>
+#include <wpi/concepts.h>
 #include <wpi/mutex.h>
 
 namespace frc {
@@ -36,9 +36,8 @@ class Notifier {
    */
   explicit Notifier(std::function<void()> handler);
 
-  template <
-      typename Callable, typename Arg, typename... Args,
-      typename = std::enable_if_t<std::is_invocable_v<Callable, Arg, Args...>>>
+  template <typename Callable, typename Arg, typename... Args>
+    requires std::invocable<Callable, Arg, Args...>
   Notifier(Callable&& f, Arg&& arg, Args&&... args)
       : Notifier(std::bind(std::forward<Callable>(f), std::forward<Arg>(arg),
                            std::forward<Args>(args)...)) {}
@@ -59,6 +58,7 @@ class Notifier {
   explicit Notifier(int priority, std::function<void()> handler);
 
   template <typename Callable, typename Arg, typename... Args>
+    requires std::invocable<Callable, Arg, Args...>
   Notifier(int priority, Callable&& f, Arg&& arg, Args&&... args)
       : Notifier(priority,
                  std::bind(std::forward<Callable>(f), std::forward<Arg>(arg),

wpilibc/src/main/native/include/frc/smartdashboard/MechanismObject2d.h

@@ -8,11 +8,11 @@
 #include <stdexcept>
 #include <string>
 #include <string_view>
-#include <type_traits>
 #include <utility>
 
 #include <networktables/NetworkTable.h>
 #include <wpi/StringMap.h>
+#include <wpi/concepts.h>
 
 #include "frc/Errors.h"
 
@@ -62,9 +62,8 @@ class MechanismObject2d {
    * assignments and call chaining.
    * @throw if an object with the given name already exists.
    */
-  template <typename T, typename... Args,
-            typename =
-                std::enable_if_t<std::is_convertible_v<T*, MechanismObject2d*>>>
+  template <typename T, typename... Args>
+    requires std::convertible_to<T*, MechanismObject2d*>
   T* Append(std::string_view name, Args&&... args) {
     std::scoped_lock lock(m_mutex);
     auto& obj = m_objects[name];

wpilibc/src/main/native/include/frc/smartdashboard/SendableChooser.h

@@ -8,6 +8,7 @@
 #include <string_view>
 
 #include <wpi/StringMap.h>
+#include <wpi/concepts.h>
 
 #include "frc/smartdashboard/SendableChooserBase.h"
 
@@ -27,12 +28,9 @@ namespace frc {
  * @see SmartDashboard
  */
 template <class T>
+  requires std::copy_constructible<T> && std::default_initializable<T>
 class SendableChooser : public SendableChooserBase {
   wpi::StringMap<T> m_choices;
-  static_assert(std::is_copy_constructible_v<T>,
-                "T must be copy-constructible!");
-  static_assert(std::is_default_constructible_v<T>,
-                "T must be default-constructible!");
 
   template <class U>
   static U _unwrap_smart_ptr(const U& value);

wpilibc/src/main/native/include/frc/smartdashboard/SendableChooser.inc

@@ -18,17 +18,20 @@
 namespace frc {
 
 template <class T>
+  requires std::copy_constructible<T> && std::default_initializable<T>
 void SendableChooser<T>::AddOption(std::string_view name, T object) {
   m_choices[name] = std::move(object);
 }
 
 template <class T>
+  requires std::copy_constructible<T> && std::default_initializable<T>
 void SendableChooser<T>::SetDefaultOption(std::string_view name, T object) {
   m_defaultChoice = name;
   AddOption(name, std::move(object));
 }
 
 template <class T>
+  requires std::copy_constructible<T> && std::default_initializable<T>
 auto SendableChooser<T>::GetSelected()
     -> decltype(_unwrap_smart_ptr(m_choices[""])) {
   std::string selected = m_defaultChoice;
@@ -46,6 +49,7 @@ auto SendableChooser<T>::GetSelected()
 }
 
 template <class T>
+  requires std::copy_constructible<T> && std::default_initializable<T>
 void SendableChooser<T>::InitSendable(nt::NTSendableBuilder& builder) {
   builder.SetSmartDashboardType("String Chooser");
   {
@@ -101,18 +105,21 @@ void SendableChooser<T>::InitSendable(nt::NTSendableBuilder& builder) {
 }
 
 template <class T>
+  requires std::copy_constructible<T> && std::default_initializable<T>
 template <class U>
 U SendableChooser<T>::_unwrap_smart_ptr(const U& value) {
   return value;
 }
 
 template <class T>
+  requires std::copy_constructible<T> && std::default_initializable<T>
 template <class U>
 U* SendableChooser<T>::_unwrap_smart_ptr(const std::unique_ptr<U>& value) {
   return value.get();
 }
 
 template <class T>
+  requires std::copy_constructible<T> && std::default_initializable<T>
 template <class U>
 std::weak_ptr<U> SendableChooser<T>::_unwrap_smart_ptr(
     const std::shared_ptr<U>& value) {