Implement println (#3267)

include/fmt/core.h

@@ -3009,6 +3009,36 @@ FMT_INLINE void print(std::FILE* f, format_string<T...> fmt, T&&... args) {
                            : detail::vprint_mojibake(f, fmt, vargs);
 }
 
+/**
+  \rst
+  Formats ``args`` according to specifications in ``fmt`` and writes the
+  output to the file ``f`` followed by a newline.
+
+  **Example**::
+
+       fmt::println(stderr, "Don't {}!", "panic");
+  \endrst
+ */
+template <typename... T>
+FMT_INLINE void println(std::FILE* f, format_string<T...> fmt, T&&... args) {
+  return fmt::print(f, "{}\n", fmt::format(fmt, std::forward<T>(args)...));
+}
+
+/**
+  \rst
+  Formats ``args`` according to specifications in ``fmt`` and writes the output
+  to ``stdout`` followed by a newline.
+
+  **Example**::
+
+       fmt::println("Elapsed time: {0:.2f} seconds", 1.23);
+  \endrst
+ */
+template <typename... T>
+FMT_INLINE void println(format_string<T...> fmt, T&&... args) {
+  return fmt::println(stdout, fmt, std::forward<T>(args)...);
+}
+
 FMT_MODULE_EXPORT_END
 FMT_GCC_PRAGMA("GCC pop_options")
 FMT_END_NAMESPACE

include/fmt/ostream.h

@@ -232,6 +232,19 @@ void print(std::wostream& os,
   vprint(os, fmt, fmt::make_format_args<buffer_context<wchar_t>>(args...));
 }
 
+FMT_MODULE_EXPORT template <typename... T>
+void println(std::ostream& os, format_string<T...> fmt, T&&... args) {
+  print(os, "{}\n", fmt::format(fmt, std::forward<T>(args)...));
+}
+
+FMT_MODULE_EXPORT
+template <typename... Args>
+void println(std::wostream& os,
+             basic_format_string<wchar_t, type_identity_t<Args>...> fmt,
+             Args&&... args) {
+  print(os, L"{}\n", fmt::format(fmt, std::forward<Args>(args)...));
+}
+
 FMT_END_NAMESPACE
 
 #endif  // FMT_OSTREAM_H_

include/fmt/xchar.h

@@ -238,6 +238,15 @@ template <typename... T> void print(wformat_string<T...> fmt, T&&... args) {
   return vprint(wstring_view(fmt), fmt::make_wformat_args(args...));
 }
 
+template <typename... T>
+void println(std::FILE* f, wformat_string<T...> fmt, T&&... args) {
+  return print(f, L"{}\n", fmt::format(fmt, std::forward<T>(args)...));
+}
+
+template <typename... T> void println(wformat_string<T...> fmt, T&&... args) {
+  return print(L"{}\n", fmt::format(fmt, std::forward<T>(args)...));
+}
+
 /**
   Converts *value* to ``std::wstring`` using the default format for type *T*.
  */