Add a constructor to `VariantData`

extras/tests/JsonVariant/misc.cpp

@@ -5,6 +5,11 @@
 #include <ArduinoJson.h>
 #include <catch.hpp>
 
+TEST_CASE("VariantData") {
+  REQUIRE(std::is_standard_layout<ArduinoJson::detail::VariantData>::value ==
+          true);
+}
+
 TEST_CASE("JsonVariant from JsonArray") {
   SECTION("JsonArray is null") {
     JsonArray arr;

extras/tests/Numbers/parseNumber.cpp

@@ -10,8 +10,6 @@ using namespace ArduinoJson::detail;
 
 TEST_CASE("Test unsigned integer overflow") {
   VariantData first, second;
-  first.init();
-  second.init();
 
   // Avoids MSVC warning C4127 (conditional expression is constant)
   size_t integerSize = sizeof(JsonInteger);
@@ -30,8 +28,6 @@ TEST_CASE("Test unsigned integer overflow") {
 
 TEST_CASE("Test signed integer overflow") {
   VariantData first, second;
-  first.init();
-  second.init();
 
   // Avoids MSVC warning C4127 (conditional expression is constant)
   size_t integerSize = sizeof(JsonInteger);
@@ -50,7 +46,6 @@ TEST_CASE("Test signed integer overflow") {
 
 TEST_CASE("Invalid value") {
   VariantData result;
-  result.init();
 
   parseNumber("6a3", result);
 

src/ArduinoJson/Document/JsonDocument.hpp

@@ -41,7 +41,7 @@ class JsonDocument : public detail::VariantOperators<const JsonDocument&> {
   // https://arduinojson.org/v6/api/jsondocument/clear/
   void clear() {
     _pool.clear();
-    _data.init();
+    _data.setNull();
   }
 
   // Returns true if the root is of the specified type.
@@ -277,17 +277,11 @@ class JsonDocument : public detail::VariantOperators<const JsonDocument&> {
   }
 
  protected:
-  JsonDocument() : _pool(0, 0) {
-    _data.init();
-  }
+  JsonDocument() : _pool(0, 0) {}
 
-  JsonDocument(detail::MemoryPool pool) : _pool(pool) {
-    _data.init();
-  }
+  JsonDocument(detail::MemoryPool pool) : _pool(pool) {}
 
-  JsonDocument(char* buf, size_t capa) : _pool(buf, capa) {
-    _data.init();
-  }
+  JsonDocument(char* buf, size_t capa) : _pool(buf, capa) {}
 
   ~JsonDocument() {}
 

src/ArduinoJson/Numbers/parseNumber.hpp

@@ -146,7 +146,6 @@ inline bool parseNumber(const char* s, VariantData& result) {
 template <typename T>
 inline T parseNumber(const char* s) {
   VariantData value;
-  value.init();  // VariantData is a POD, so it has no constructor
   parseNumber(s, value);
   return Converter<T>::fromJson(JsonVariantConst(&value));
 }

src/ArduinoJson/Variant/VariantData.hpp

@@ -11,16 +11,6 @@
 #include <ArduinoJson/Strings/StringAdapters.hpp>
 #include <ArduinoJson/Variant/VariantContent.hpp>
 
-// VariantData can't have a constructor (to be a POD), so we have no way to fix
-// this warning
-#if defined(__GNUC__)
-#  if __GNUC__ >= 7
-#    pragma GCC diagnostic push
-#    pragma GCC diagnostic ignored "-Wmaybe-uninitialized"
-#    pragma GCC diagnostic ignored "-Wuninitialized"
-#  endif
-#endif
-
 ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE
 
 class VariantData {
@@ -28,14 +18,7 @@ class VariantData {
   uint8_t _flags;
 
  public:
-  // Must be a POD!
-  // - no constructor
-  // - no destructor
-  // - no virtual
-  // - no inheritance
-  void init() {
-    _flags = VALUE_IS_NULL;
-  }
+  VariantData() : _flags(VALUE_IS_NULL) {}
 
   void operator=(const VariantData& src) {
     _content = src._content;
@@ -337,9 +320,3 @@ class VariantData {
 };
 
 ARDUINOJSON_END_PRIVATE_NAMESPACE
-
-#if defined(__GNUC__)
-#  if __GNUC__ >= 8
-#    pragma GCC diagnostic pop
-#  endif
-#endif