Use FMT_DISALLOW_COPY_AND_ASSIGN instead of undefined assignment operators

format.cc

@@ -240,10 +240,10 @@ void check_sign(const Char *&s, const Arg &arg) {
 // left alignment if it is negative.
 class WidthHandler : public fmt::internal::ArgVisitor<WidthHandler, unsigned> {
  private:
-  WidthHandler& operator=(WidthHandler const&); //no impl
-
   fmt::FormatSpec &spec_;
 
+  FMT_DISALLOW_COPY_AND_ASSIGN(WidthHandler);
+
  public:
   explicit WidthHandler(fmt::FormatSpec &spec) : spec_(spec) {}
 
@@ -286,11 +286,11 @@ class PrecisionHandler :
 template <typename T>
 class ArgConverter : public fmt::internal::ArgVisitor<ArgConverter<T>, void> {
  private:
-  ArgConverter& operator=(ArgConverter const&); //no impl
-
   fmt::internal::Arg &arg_;
   wchar_t type_;
 
+  FMT_DISALLOW_COPY_AND_ASSIGN(ArgConverter);
+
  public:
   ArgConverter(fmt::internal::Arg &arg, wchar_t type)
     : arg_(arg), type_(type) {}
@@ -326,9 +326,10 @@ class ArgConverter : public fmt::internal::ArgVisitor<ArgConverter<T>, void> {
 // Converts an integer argument to char for printf.
 class CharConverter : public fmt::internal::ArgVisitor<CharConverter, void> {
  private:
-  CharConverter& operator=(CharConverter const&); // no impl
   fmt::internal::Arg &arg_;
 
+  FMT_DISALLOW_COPY_AND_ASSIGN(CharConverter);
+
  public:
   explicit CharConverter(fmt::internal::Arg &arg) : arg_(arg) {}
 
@@ -531,13 +532,13 @@ template <typename Char>
 class fmt::internal::ArgFormatter :
     public fmt::internal::ArgVisitor<fmt::internal::ArgFormatter<Char>, void> {
  private:
-  ArgFormatter& operator=(ArgFormatter const&); // no impl
-
   fmt::BasicFormatter<Char> &formatter_;
   fmt::BasicWriter<Char> &writer_;
   fmt::FormatSpec &spec_;
   const Char *format_;
 
+  FMT_DISALLOW_COPY_AND_ASSIGN(ArgFormatter);
+
  public:
   ArgFormatter(
       fmt::BasicFormatter<Char> &f,fmt::FormatSpec &s, const Char *fmt)

format.h

@@ -991,10 +991,10 @@ class PrintfFormatter : private FormatterBase {
 template <typename Char>
 class BasicFormatter : private internal::FormatterBase {
  private:
-  BasicFormatter& operator=(BasicFormatter const&); // no impl
-
   BasicWriter<Char> &writer_;
   const Char *start_;
+  
+  FMT_DISALLOW_COPY_AND_ASSIGN(BasicFormatter);
 
   // Parses argument index and returns corresponding argument.
   internal::Arg parse_arg_index(const Char *&s);