STYLE: Pefer = default to explicitly trivial implementations

This check replaces default bodies of special member functions with
= default;. The explicitly defaulted function declarations enable more
opportunities in optimization, because the compiler might treat
explicitly defaulted functions as trivial.

Additionally, the C++11 use of = default more clearly expreses the
intent for the special member functions.

SRCDIR=/Users/johnsonhj/src/jsoncpp/ #My local SRC
BLDDIR=/Users/johnsonhj/src/jsoncpp/cmake-build-debug/ #My local BLD

cd /Users/johnsonhj/src/jsoncpp/cmake-build-debug/
run-clang-tidy.py -extra-arg=-D__clang__ -checks=-*,modernize-use-equals-default  -header-filter=.* -fix

Author: hjmjohnson

Diff for: include/json/reader.h

@@ -256,7 +256,7 @@ class JSON_API Reader {
  */
 class JSON_API CharReader {
 public:
-  virtual ~CharReader() {}
+  virtual ~CharReader() = default;
   /** \brief Read a Value from a <a HREF="http://www.json.org">JSON</a>
    document.
    * The document must be a UTF-8 encoded string containing the document to
@@ -282,7 +282,7 @@ class JSON_API CharReader {
 
   class JSON_API Factory {
   public:
-    virtual ~Factory() {}
+    virtual ~Factory() = default;
     /** \brief Allocate a CharReader via operator new().
      * \throw std::exception if something goes wrong (e.g. invalid settings)
      */

Diff for: include/json/writer.h

@@ -169,7 +169,7 @@ class JSONCPP_DEPRECATED("Use StreamWriterBuilder instead") JSON_API FastWriter
     : public Writer {
 public:
   FastWriter();
-  ~FastWriter() override {}
+  ~FastWriter() override = default;
 
   void enableYAMLCompatibility();
 
@@ -229,7 +229,7 @@ class JSONCPP_DEPRECATED("Use StreamWriterBuilder instead") JSON_API
     StyledWriter : public Writer {
 public:
   StyledWriter();
-  ~StyledWriter() override {}
+  ~StyledWriter() override = default;
 
 public: // overridden from Writer
   /** \brief Serialize a Value in <a HREF="http://www.json.org">JSON</a> format.
@@ -301,7 +301,7 @@ class JSONCPP_DEPRECATED("Use StreamWriterBuilder instead") JSON_API
    * \param indentation Each level will be indented by this amount extra.
    */
   StyledStreamWriter(JSONCPP_STRING  indentation = "\t");
-  ~StyledStreamWriter() {}
+  ~StyledStreamWriter() = default;
 
 public:
   /** \brief Serialize a Value in <a HREF="http://www.json.org">JSON</a> format.

Diff for: src/lib_json/json_reader.cpp

@@ -60,7 +60,7 @@ typedef std::auto_ptr<CharReader> CharReaderPtr;
 // ////////////////////////////////
 
 Features::Features()
-     {}
+     = default;
 
 Features Features::all() { return {}; }
 
@@ -1907,7 +1907,7 @@ class OurCharReader : public CharReader {
 };
 
 CharReaderBuilder::CharReaderBuilder() { setDefaults(&settings_); }
-CharReaderBuilder::~CharReaderBuilder() {}
+CharReaderBuilder::~CharReaderBuilder() = default;
 CharReader* CharReaderBuilder::newCharReader() const {
   bool collectComments = settings_["collectComments"].asBool();
   OurFeatures features = OurFeatures::all();

Diff for: src/lib_json/json_value.cpp

@@ -214,7 +214,7 @@ static inline void releaseStringValue(char* value, unsigned) { free(value); }
 namespace Json {
 
 Exception::Exception(JSONCPP_STRING  msg) : msg_(std::move(msg)) {}
-Exception::~Exception() JSONCPP_NOEXCEPT {}
+Exception::~Exception() JSONCPP_NOEXCEPT = default;
 char const* Exception::what() const JSONCPP_NOEXCEPT { return msg_.c_str(); }
 RuntimeError::RuntimeError(JSONCPP_STRING const& msg) : Exception(msg) {}
 LogicError::LogicError(JSONCPP_STRING const& msg) : Exception(msg) {}
@@ -233,7 +233,7 @@ JSONCPP_NORETURN void throwLogicError(JSONCPP_STRING const& msg) {
 // //////////////////////////////////////////////////////////////////
 // //////////////////////////////////////////////////////////////////
 
-Value::CommentInfo::CommentInfo()  {}
+Value::CommentInfo::CommentInfo()  = default;
 
 Value::CommentInfo::~CommentInfo() {
   if (comment_)

Diff for: src/lib_json/json_valueiterator.inl

@@ -123,7 +123,7 @@ char const* ValueIteratorBase::memberName(char const** end) const {
 // //////////////////////////////////////////////////////////////////
 // //////////////////////////////////////////////////////////////////
 
-ValueConstIterator::ValueConstIterator() {}
+ValueConstIterator::ValueConstIterator() = default;
 
 ValueConstIterator::ValueConstIterator(
     const Value::ObjectValues::iterator& current)
@@ -146,7 +146,7 @@ operator=(const ValueIteratorBase& other) {
 // //////////////////////////////////////////////////////////////////
 // //////////////////////////////////////////////////////////////////
 
-ValueIterator::ValueIterator() {}
+ValueIterator::ValueIterator() = default;
 
 ValueIterator::ValueIterator(const Value::ObjectValues::iterator& current)
     : ValueIteratorBase(current) {}
@@ -157,7 +157,7 @@ ValueIterator::ValueIterator(const ValueConstIterator& other)
 }
 
 ValueIterator::ValueIterator(const ValueIterator& other)
-    : ValueIteratorBase(other) {}
+     = default;
 
 ValueIterator& ValueIterator::operator=(const SelfType& other) {
   copy(other);

Diff for: src/lib_json/json_writer.cpp

@@ -346,14 +346,14 @@ JSONCPP_STRING valueToQuotedString(const char* value) {
 
 // Class Writer
 // //////////////////////////////////////////////////////////////////
-Writer::~Writer() {}
+Writer::~Writer() = default;
 
 // Class FastWriter
 // //////////////////////////////////////////////////////////////////
 
 FastWriter::FastWriter()
 
-      {}
+      = default;
 
 void FastWriter::enableYAMLCompatibility() { yamlCompatibilityEnabled_ = true; }
 
@@ -428,7 +428,7 @@ void FastWriter::writeValue(const Value& value) {
 // //////////////////////////////////////////////////////////////////
 
 StyledWriter::StyledWriter()
-     {}
+     = default;
 
 JSONCPP_STRING StyledWriter::write(const Value& root) {
   document_.clear();
@@ -1156,10 +1156,10 @@ bool BuiltStyledStreamWriter::hasCommentForValue(const Value& value) {
 // StreamWriter
 
 StreamWriter::StreamWriter() : sout_(nullptr) {}
-StreamWriter::~StreamWriter() {}
-StreamWriter::Factory::~Factory() {}
+StreamWriter::~StreamWriter() = default;
+StreamWriter::Factory::~Factory() = default;
 StreamWriterBuilder::StreamWriterBuilder() { setDefaults(&settings_); }
-StreamWriterBuilder::~StreamWriterBuilder() {}
+StreamWriterBuilder::~StreamWriterBuilder() = default;
 StreamWriter* StreamWriterBuilder::newStreamWriter() const {
   JSONCPP_STRING indentation = settings_["indentation"].asString();
   JSONCPP_STRING cs_str = settings_["commentStyle"].asString();

Diff for: src/test_lib_json/jsontest.cpp

@@ -207,9 +207,9 @@ TestResult& TestResult::operator<<(bool value) {
 // class TestCase
 // //////////////////////////////////////////////////////////////////
 
-TestCase::TestCase()  {}
+TestCase::TestCase()  = default;
 
-TestCase::~TestCase() {}
+TestCase::~TestCase() = default;
 
 void TestCase::run(TestResult& result) {
   result_ = &result;
@@ -219,7 +219,7 @@ void TestCase::run(TestResult& result) {
 // class Runner
 // //////////////////////////////////////////////////////////////////
 
-Runner::Runner() {}
+Runner::Runner() = default;
 
 Runner& Runner::add(TestCaseFactory factory) {
   tests_.push_back(factory);

Diff for: src/test_lib_json/main.cpp

@@ -1332,7 +1332,7 @@ void ValueTest::checkMemberCount(Json::Value& value,
 
 ValueTest::IsCheck::IsCheck()
 
-      {}
+      = default;
 
 void ValueTest::checkIs(const Json::Value& value, const IsCheck& check) {
   JSONTEST_ASSERT_EQUAL(check.isObject_, value.isObject());