Use ArgInfo instead of Arg where possible.

format.cc

@@ -388,7 +388,7 @@ unsigned fmt::BasicFormatter<Char>::ParseUInt(const Char *&s) const {
 }
 
 template <typename Char>
-inline const typename fmt::BasicFormatter<Char>::Arg
+inline const typename fmt::BasicFormatter<Char>::ArgInfo
     &fmt::BasicFormatter<Char>::ParseArgIndex(const Char *&s) {
   unsigned arg_index = 0;
   if (*s < '0' || *s > '9') {
@@ -409,11 +409,11 @@ inline const typename fmt::BasicFormatter<Char>::Arg
   }
   if (arg_index >= args_.size())
     ReportError(s, "argument index is out of range in format");
-  return *args_[arg_index];
+  return args_[arg_index];
 }
 
 template <typename Char>
-void fmt::BasicFormatter<Char>::CheckSign(const Char *&s, const Arg &arg) {
+void fmt::BasicFormatter<Char>::CheckSign(const Char *&s, const ArgInfo &arg) {
   char sign = static_cast<char>(*s);
   if (arg.type > LAST_NUMERIC_TYPE) {
     ReportError(s,
@@ -446,7 +446,7 @@ void fmt::BasicFormatter<Char>::DoFormat() {
     num_open_braces_= 1;
     writer.buffer_.append(start, s - 1);
 
-    const Arg &arg = ParseArgIndex(s);
+    const ArgInfo &arg = ParseArgIndex(s);
 
     FormatSpec spec;
     int precision = -1;
@@ -537,7 +537,7 @@ void fmt::BasicFormatter<Char>::DoFormat() {
         } else if (*s == '{') {
           ++s;
           ++num_open_braces_;
-          const Arg &precision_arg = ParseArgIndex(s);
+          const ArgInfo &precision_arg = ParseArgIndex(s);
           ULongLong value = 0;
           switch (precision_arg.type) {
           case INT:
@@ -702,11 +702,11 @@ template void fmt::BasicFormatter<char>::ReportError(
 
 template unsigned fmt::BasicFormatter<char>::ParseUInt(const char *&s) const;
 
-template const fmt::BasicFormatter<char>::Arg
+template const fmt::BasicFormatter<char>::ArgInfo
     &fmt::BasicFormatter<char>::ParseArgIndex(const char *&s);
 
 template void fmt::BasicFormatter<char>::CheckSign(
-    const char *&s, const Arg &arg);
+    const char *&s, const ArgInfo &arg);
 
 template void fmt::BasicFormatter<char>::DoFormat();
 
@@ -732,11 +732,11 @@ template void fmt::BasicFormatter<wchar_t>::ReportError(
 template unsigned fmt::BasicFormatter<wchar_t>::ParseUInt(
     const wchar_t *&s) const;
 
-template const fmt::BasicFormatter<wchar_t>::Arg
+template const fmt::BasicFormatter<wchar_t>::ArgInfo
     &fmt::BasicFormatter<wchar_t>::ParseArgIndex(const wchar_t *&s);
 
 template void fmt::BasicFormatter<wchar_t>::CheckSign(
-    const wchar_t *&s, const Arg &arg);
+    const wchar_t *&s, const ArgInfo &arg);
 
 template void fmt::BasicFormatter<wchar_t>::DoFormat();
 

format.h

@@ -1031,7 +1031,15 @@ class BasicFormatter {
   };
 
   // A wrapper around a format argument used to ensure that the formatting
-  // is performed before the argument is destroyed.
+  // is performed before the argument is destroyed. It is private so that
+  // its objects are only created by automatic conversions and not by users.
+  // Example:
+  //
+  //   Format("{}") << std::string("test");
+  //
+  // Here an Arg object that wraps a temporary string is automatically
+  // created. It triggers formatting when destroyed which makes sure that
+  // the temporary string is still alive at the time of the formatting.
   class Arg : public ArgInfo {
    private:
     // This method is private to disallow formatting of arbitrary pointers.
@@ -1118,7 +1126,7 @@ class BasicFormatter {
       // Format is called here to make sure that a referred object is
       // still alive, for example:
       //
-      //   Print("{0}") << std::string("test");
+      //   Print("{}") << std::string("test");
       //
       // Here an Arg object refers to a temporary std::string which is
       // destroyed at the end of the statement. Since the string object is
@@ -1132,7 +1140,7 @@ class BasicFormatter {
   };
 
   enum { NUM_INLINE_ARGS = 10 };
-  internal::Array<const Arg*, NUM_INLINE_ARGS> args_;  // Format arguments.
+  internal::Array<ArgInfo, NUM_INLINE_ARGS> args_;  // Format arguments.
 
   const Char *format_;  // Format string.
   int num_open_braces_;
@@ -1153,9 +1161,9 @@ class BasicFormatter {
   unsigned ParseUInt(const Char *&s) const;
 
   // Parses argument index and returns an argument with this index.
-  const Arg &ParseArgIndex(const Char *&s);
+  const ArgInfo &ParseArgIndex(const Char *&s);
 
-  void CheckSign(const Char *&s, const Arg &arg);
+  void CheckSign(const Char *&s, const ArgInfo &arg);
 
   // Parses the format string and performs the actual formatting,
   // writing the output to writer_.
@@ -1194,7 +1202,7 @@ class BasicFormatter {
     // TODO: don't copy arguments
     args_.reserve(args.size());
     for (const Arg &arg: args)
-      args_.push_back(&arg);
+      args_.push_back(arg);
   }
 #endif
 
@@ -1211,7 +1219,7 @@ class BasicFormatter {
   // Feeds an argument to a formatter.
   BasicFormatter &operator<<(const Arg &arg) {
     arg.formatter = this;
-    args_.push_back(&arg);
+    args_.push_back(arg);
     return *this;
   }