Allow mixed configuration in compilation units (issue #809)

test/MixedConfiguration/use_long_long_0.cpp

@@ -0,0 +1,30 @@
+#define ARDUINOJSON_USE_LONG_LONG 0
+#include <ArduinoJson.h>
+
+#include <catch.hpp>
+
+template <size_t size_of_long>
+std::string get_expected_json();
+
+template <>
+std::string get_expected_json<4>() {
+  return "{\"A\":2899336981,\"B\":2129924785}";
+}
+
+template <>
+std::string get_expected_json<8>() {
+  return "{\"A\":123456789123456789,\"B\":987654321987654321}";
+}
+
+TEST_CASE("ARDUINOJSON_USE_LONG_LONG == 0") {
+  DynamicJsonDocument doc;
+  JsonObject root = doc.to<JsonObject>();
+
+  root["A"] = 123456789123456789;
+  root["B"] = 987654321987654321;
+
+  std::string json;
+  serializeJson(doc, json);
+
+  REQUIRE(json == get_expected_json<sizeof(long)>());
+}