Fix more compilation errors on gcc 4.6

include/fmt/format.h

@@ -2658,7 +2658,8 @@ void basic_writer<Range>::write_double(T value, const format_specs &spec) {
   }
 
   auto write_inf_or_nan = [this, &spec, sign](const char *str) {
-    write_padded(INF_SIZE + (sign ? 1 : 0), spec, inf_or_nan_writer{sign, str});
+    this->write_padded(INF_SIZE + (sign ? 1 : 0), spec,
+                       inf_or_nan_writer{sign, str});
   };
 
   // Format NaN and ininity ourselves because sprintf's output is not consistent

include/fmt/ostream.h

@@ -67,8 +67,10 @@ class convert_to_int<T, Char, true> {
   template <typename>
   static std::false_type test(...);
 
+  typedef decltype(test<T>(0)) result;
+
  public:
-  static const bool value = !decltype(test<T>(0))::value;
+  static const bool value = !result::value;
 };
 
 // Write the content of buf to os.

include/fmt/printf.h

@@ -290,7 +290,7 @@ class printf_arg_formatter : public internal::arg_formatter_base<Range> {
 template <typename T>
 struct printf_formatter {
   template <typename ParseContext>
-  auto parse(ParseContext &ctx) { return ctx.begin(); }
+  auto parse(ParseContext &ctx) -> decltype(ctx.begin()) { return ctx.begin(); }
 
   template <typename FormatContext>
   auto format(const T &value, FormatContext &ctx) -> decltype(ctx.begin()) {