some bug fixes to attribute fork to get compilation working

include/spdlog/details/log_attr.h

@@ -28,7 +28,7 @@ public:
 
     template <typename T>
     attr(std::string_view k, T const &v)
-        : key
+        : key{k}
         , value{std::to_string(v)}
     {}
 };

include/spdlog/details/log_msg_buffer-inl.h

@@ -21,7 +21,7 @@ SPDLOG_INLINE log_msg_buffer::log_msg_buffer(const log_msg &orig_msg)
 
 SPDLOG_INLINE log_msg_buffer::log_msg_buffer(const log_msg_buffer &other)
     : log_msg{other}
-    , attributes{orig_msg.attributes}
+    , attributes{other.attributes}
 {
     buffer.append(logger_name.begin(), logger_name.end());
     buffer.append(payload.begin(), payload.end());

include/spdlog/details/log_msg_buffer.h

@@ -14,6 +14,7 @@ namespace details {
 class SPDLOG_API log_msg_buffer : public log_msg
 {
     memory_buf_t buffer;
+    std::vector<attr> attributes;
     void update_string_views();
 
 public: