print debug [OC-2764]

Author: john-michaelburke

core/src/registry.cc

@@ -5,6 +5,7 @@
 #include <iterator>
 #include <stdexcept>
 #include <tuple>
+#include <iostream>
 
 #include "prometheus/counter.h"
 #include "prometheus/detail/future_std.h"
@@ -108,6 +109,16 @@ Family<T>& Registry::Add(const std::string& name, const std::string& help,
   std::lock_guard<std::mutex> lock{mutex_};
 
   if (NameExistsInOtherType<T>(name)) {
+    std::cerr << "Family name already exists with different type (name '" << name
+              << "', type: '" << typeid(T).name() << "')"
+              << std::endl;
+    std::cerr << "help: " << help << std::endl;
+    std::cerr << "labels: ";
+    for (const auto& label : labels) {
+      std::cerr << label.first << "=" << label.second << ",";
+    }
+    std::cerr << std::endl;
+
     throw std::invalid_argument(
         "Family name already exists with different type");
   }