Merge branch 'v1.x' of https://github.com/gabime/spdlog into v1.x

README.md

@@ -273,6 +273,7 @@ void async_example()
 ---
 #### Asynchronous logger with multi sinks
 ```c++
+#include "spdlog/async.h"
 #include "spdlog/sinks/stdout_color_sinks.h"
 #include "spdlog/sinks/rotating_file_sink.h"
 

include/spdlog/common.h

@@ -319,7 +319,7 @@ struct source_loc {
           line{line_in},
           funcname{funcname_in} {}
 
-    SPDLOG_CONSTEXPR bool empty() const SPDLOG_NOEXCEPT { return line == 0; }
+    SPDLOG_CONSTEXPR bool empty() const SPDLOG_NOEXCEPT { return line <= 0; }
     const char *filename{nullptr};
     int line{0};
     const char *funcname{nullptr};