Perfect forwarding for arguments

include/spdlog/logger.h

@@ -75,58 +75,58 @@ public:
 
     // FormatString is a type derived from fmt::compile_string
     template<typename FormatString, typename std::enable_if<fmt::is_compile_string<FormatString>::value, int>::type = 0, typename... Args>
-    void log(source_loc loc, level::level_enum lvl, const FormatString &fmt, const Args &...args)
+    void log(source_loc loc, level::level_enum lvl, const FormatString &fmt, Args&&...args)
     {
-        log_(loc, lvl, fmt, args...);
+        log_(loc, lvl, fmt, std::forward<Args>(args)...);
     }
 
     // FormatString is NOT a type derived from fmt::compile_string but is a string_view_t or can be implicitly converted to one
     template<typename... Args>
-    void log(source_loc loc, level::level_enum lvl, string_view_t fmt, const Args &...args)
+    void log(source_loc loc, level::level_enum lvl, string_view_t fmt, Args&&...args)
     {
-        log_(loc, lvl, fmt, args...);
+        log_(loc, lvl, fmt, std::forward<Args>(args)...);
     }
 
     template<typename FormatString, typename... Args>
-    void log(level::level_enum lvl, const FormatString &fmt, const Args &...args)
+    void log(level::level_enum lvl, const FormatString &fmt, Args&&...args)
     {
-        log(source_loc{}, lvl, fmt, args...);
+        log(source_loc{}, lvl, fmt, std::forward<Args>(args)...);
     }
 
     template<typename FormatString, typename... Args>
-    void trace(const FormatString &fmt, const Args &...args)
+    void trace(const FormatString &fmt, Args&&...args)
     {
-        log(level::trace, fmt, args...);
+        log(level::trace, fmt, std::forward<Args>(args)...);
     }
 
     template<typename FormatString, typename... Args>
-    void debug(const FormatString &fmt, const Args &...args)
+    void debug(const FormatString &fmt, Args&&...args)
     {
-        log(level::debug, fmt, args...);
+        log(level::debug, fmt, std::forward<Args>(args)...);
     }
 
     template<typename FormatString, typename... Args>
-    void info(const FormatString &fmt, const Args &...args)
+    void info(const FormatString &fmt, Args&&...args)
     {
-        log(level::info, fmt, args...);
+        log(level::info, fmt, std::forward<Args>(args)...);
     }
 
     template<typename FormatString, typename... Args>
-    void warn(const FormatString &fmt, const Args &...args)
+    void warn(const FormatString &fmt, Args&&...args)
     {
-        log(level::warn, fmt, args...);
+        log(level::warn, fmt, std::forward<Args>(args)...);
     }
 
     template<typename FormatString, typename... Args>
-    void error(const FormatString &fmt, const Args &...args)
+    void error(const FormatString &fmt, Args&&...args)
     {
-        log(level::err, fmt, args...);
+        log(level::err, fmt, std::forward<Args>(args)...);
     }
 
     template<typename FormatString, typename... Args>
-    void critical(const FormatString &fmt, const Args &...args)
+    void critical(const FormatString &fmt, Args&&...args)
     {
-        log(level::critical, fmt, args...);
+        log(level::critical, fmt, std::forward<Args>(args)...);
     }
 
     template<typename T>
@@ -225,7 +225,7 @@ public:
 #else
 
     template<typename... Args>
-    void log(source_loc loc, level::level_enum lvl, wstring_view_t fmt, const Args &...args)
+    void log(source_loc loc, level::level_enum lvl, wstring_view_t fmt, Args&&...args)
     {
         bool log_enabled = should_log(lvl);
         bool traceback_enabled = tracer_.enabled();
@@ -237,7 +237,7 @@ public:
         {
             // format to wmemory_buffer and convert to utf8
             fmt::wmemory_buffer wbuf;
-            fmt::format_to(wbuf, fmt, args...);
+            fmt::format_to(wbuf, fmt, std::forward<Args>(args)...);
 
             memory_buf_t buf;
             details::os::wstr_to_utf8buf(wstring_view_t(wbuf.data(), wbuf.size()), buf);
@@ -326,7 +326,7 @@ protected:
 
     // common implementation for after templated public api has been resolved
     template<typename FormatString, typename... Args>
-    void log_(source_loc loc, level::level_enum lvl, const FormatString &fmt, const Args &...args)
+    void log_(source_loc loc, level::level_enum lvl, const FormatString &fmt, Args&&...args)
     {
         bool log_enabled = should_log(lvl);
         bool traceback_enabled = tracer_.enabled();
@@ -337,7 +337,7 @@ protected:
         SPDLOG_TRY
         {
             memory_buf_t buf;
-            fmt::format_to(buf, fmt, args...);
+            fmt::format_to(buf, fmt, std::forward<Args>(args)...);
             details::log_msg log_msg(loc, name_, lvl, string_view_t(buf.data(), buf.size()));
             log_it_(log_msg, log_enabled, traceback_enabled);
         }

include/spdlog/pattern_formatter.h

@@ -92,9 +92,9 @@ public:
     void format(const details::log_msg &msg, memory_buf_t &dest) override;
 
     template<typename T, typename... Args>
-    pattern_formatter &add_flag(char flag, const Args &...args)
+    pattern_formatter &add_flag(char flag, Args&&...args)
     {
-        custom_handlers_[flag] = details::make_unique<T>(args...);
+        custom_handlers_[flag] = details::make_unique<T>(std::forward<Args>(args)...);
         return *this;
     }
     void set_pattern(std::string pattern);

include/spdlog/spdlog.h

@@ -128,51 +128,51 @@ SPDLOG_API spdlog::logger *default_logger_raw();
 SPDLOG_API void set_default_logger(std::shared_ptr<spdlog::logger> default_logger);
 
 template<typename FormatString, typename... Args>
-inline void log(source_loc source, level::level_enum lvl, const FormatString &fmt, const Args &...args)
+inline void log(source_loc source, level::level_enum lvl, const FormatString &fmt, Args&&...args)
 {
-    default_logger_raw()->log(source, lvl, fmt, args...);
+    default_logger_raw()->log(source, lvl, fmt, std::forward<Args>(args)...);
 }
 
 template<typename FormatString, typename... Args>
-inline void log(level::level_enum lvl, const FormatString &fmt, const Args &...args)
+inline void log(level::level_enum lvl, const FormatString &fmt, Args&&...args)
 {
-    default_logger_raw()->log(source_loc{}, lvl, fmt, args...);
+    default_logger_raw()->log(source_loc{}, lvl, fmt, std::forward<Args>(args)...);
 }
 
 template<typename FormatString, typename... Args>
-inline void trace(const FormatString &fmt, const Args &...args)
+inline void trace(const FormatString &fmt, Args&&...args)
 {
-    default_logger_raw()->trace(fmt, args...);
+    default_logger_raw()->trace(fmt, std::forward<Args>(args)...);
 }
 
 template<typename FormatString, typename... Args>
-inline void debug(const FormatString &fmt, const Args &...args)
+inline void debug(const FormatString &fmt, Args&&...args)
 {
-    default_logger_raw()->debug(fmt, args...);
+    default_logger_raw()->debug(fmt, std::forward<Args>(args)...);
 }
 
 template<typename FormatString, typename... Args>
-inline void info(const FormatString &fmt, const Args &...args)
+inline void info(const FormatString &fmt, Args&&...args)
 {
-    default_logger_raw()->info(fmt, args...);
+    default_logger_raw()->info(fmt, std::forward<Args>(args)...);
 }
 
 template<typename FormatString, typename... Args>
-inline void warn(const FormatString &fmt, const Args &...args)
+inline void warn(const FormatString &fmt, Args&&...args)
 {
-    default_logger_raw()->warn(fmt, args...);
+    default_logger_raw()->warn(fmt, std::forward<Args>(args)...);
 }
 
 template<typename FormatString, typename... Args>
-inline void error(const FormatString &fmt, const Args &...args)
+inline void error(const FormatString &fmt, Args&&...args)
 {
-    default_logger_raw()->error(fmt, args...);
+    default_logger_raw()->error(fmt, std::forward<Args>(args)...);
 }
 
 template<typename FormatString, typename... Args>
-inline void critical(const FormatString &fmt, const Args &...args)
+inline void critical(const FormatString &fmt, Args&&...args)
 {
-    default_logger_raw()->critical(fmt, args...);
+    default_logger_raw()->critical(fmt, std::forward<Args>(args)...);
 }
 
 template<typename T>