Fix more compilation errors on gcc 4.6
diff --git a/include/fmt/printf.h b/include/fmt/printf.h
index 531f686..9720d97 100644
--- a/include/fmt/printf.h
+++ b/include/fmt/printf.h
@@ -290,7 +290,7 @@
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()) {