use C++ concepts in monitor_file_utilities

Constrained types to be integral

Author: Dr15Jones

FWCore/Services/plugins/monitor_file_utilities.h

@@ -4,6 +4,7 @@
 #include <iomanip>
 #include <iostream>
 #include <vector>
+#include <concepts>
 
 #include "FWCore/ServiceRegistry/interface/StreamContext.h"
 #include "FWCore/ServiceRegistry/interface/ModuleCallingContext.h"
@@ -23,13 +24,13 @@ namespace edm::service::monitor_file_utilities {
 
   inline auto module_callid(edm::ESModuleCallingContext const& mcc) { return mcc.callID(); }
 
-  template <typename T>
-  std::enable_if_t<std::is_integral<T>::value> concatenate(std::ostream& os, T const t) {
+  template <std::integral T>
+  void concatenate(std::ostream& os, T const t) {
     os << ' ' << t;
   }
 
-  template <typename H, typename... T>
-  std::enable_if_t<std::is_integral<H>::value> concatenate(std::ostream& os, H const h, T const... t) {
+  template <std::integral H, std::integral... T>
+  void concatenate(std::ostream& os, H const h, T const... t) {
     os << ' ' << h;
     concatenate(os, t...);
   }