Remove casting from previous commit and fix the following Klockwork issues:

1. Removing "return" from void functions.
2. Using "const" for operator= argument.

include/spdlog/details/async_log_helper.h

@@ -82,7 +82,7 @@ async_msg(async_msg&& other) SPDLOG_NOEXCEPT:
 
         // never copy or assign. should only be moved..
         async_msg(const async_msg&) = delete;
-        async_msg& operator=(async_msg& other) = delete;
+        async_msg& operator=(const async_msg& other) = delete;
 
         // construct from log_msg
         async_msg(const details::log_msg& m) :

include/spdlog/fmt/bundled/format.h

@@ -1098,7 +1098,7 @@ inline void format_decimal(Char *buffer, UInt value, unsigned num_digits,
 template <typename UInt, typename Char>
 inline void format_decimal(Char *buffer, UInt value, unsigned num_digits)
 {
-    return format_decimal(buffer, value, num_digits, NoThousandsSep());
+    format_decimal(buffer, value, num_digits, NoThousandsSep());
 }
 
 #ifndef _WIN32
@@ -2256,7 +2256,7 @@ public:
     void visit_bool(bool value)
     {
         if (spec_.type_)
-            return visit_any_int(value);
+            visit_any_int(value);
         write(value);
     }
 

include/spdlog/sinks/sink.h

@@ -15,7 +15,10 @@ namespace sinks
 class sink
 {
 public:
-    sink() { _level = (int)level::trace; }
+    sink()
+    {
+         _level = level::trace;
+    }
 
     virtual ~sink() {}
     virtual void log(const details::log_msg& msg) = 0;