Fix compilation error with NVCC (#3234)

Author: nlohmann

include/nlohmann/ordered_map.hpp

@@ -23,10 +23,10 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
     using key_type = Key;
     using mapped_type = T;
     using Container = std::vector<std::pair<const Key, T>, Allocator>;
-    using typename Container::iterator;
-    using typename Container::const_iterator;
-    using typename Container::size_type;
-    using typename Container::value_type;
+    using iterator = typename Container::iterator;
+    using const_iterator = typename Container::const_iterator;
+    using size_type = typename Container::size_type;
+    using value_type = typename Container::value_type;
 
     // Explicit constructors instead of `using Container::Container`
     // otherwise older compilers choke on it (GCC <= 5.5, xcode <= 9.4)

single_include/nlohmann/json.hpp

@@ -17041,10 +17041,10 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
     using key_type = Key;
     using mapped_type = T;
     using Container = std::vector<std::pair<const Key, T>, Allocator>;
-    using typename Container::iterator;
-    using typename Container::const_iterator;
-    using typename Container::size_type;
-    using typename Container::value_type;
+    using iterator = typename Container::iterator;
+    using const_iterator = typename Container::const_iterator;
+    using size_type = typename Container::size_type;
+    using value_type = typename Container::value_type;
 
     // Explicit constructors instead of `using Container::Container`
     // otherwise older compilers choke on it (GCC <= 5.5, xcode <= 9.4)

test/cuda_example/json_cuda.cu

@@ -4,4 +4,8 @@ int main()
 {
     nlohmann::ordered_json json = {"Test"};
     json.dump();
+
+    // regression for #3013 (ordered_json::reset() compile error with nvcc)
+    nlohmann::ordered_json metadata;
+    metadata.erase("key");
 }