use size_t to better represent thread id across platforms

include/spdlog/common.h

@@ -59,6 +59,7 @@ using log_clock = std::chrono::system_clock;
 using sink_ptr = std::shared_ptr < sinks::sink > ;
 using sinks_init_list = std::initializer_list < sink_ptr > ;
 using formatter_ptr = std::shared_ptr<spdlog::formatter>;
+using thread_id = std::size_t;
 
 //Log level enum
 namespace level

include/spdlog/details/async_log_helper.h

@@ -59,7 +59,7 @@ class async_log_helper
         std::string logger_name;
         level::level_enum level;
         log_clock::time_point time;
-        uint64_t thread_id;
+        thread_id thread_id;
         std::string txt;
 
         async_msg() = default;

include/spdlog/details/log_msg.h

@@ -92,7 +92,7 @@ struct log_msg
     std::string logger_name;
     level::level_enum level;
     log_clock::time_point time;
-    uint64_t thread_id;
+    thread_id thread_id;
     fmt::MemoryWriter raw;
     fmt::MemoryWriter formatted;
 };

include/spdlog/details/os.h

@@ -172,7 +172,7 @@ inline int utc_minutes_offset(const std::tm& tm = details::os::localtime())
 }
 
 //Return current thread id as 64 bit integer
-inline uint64_t thread_id()
+inline size_t thread_id()
 {
 
 #ifdef _WIN32