formats log messages (at least for default)

include/spdlog/details/log_attr.h

@@ -12,8 +12,8 @@ namespace details {
 
 struct attr
 {
-    std::string key;
+    std::string_view key;
-    std::string value;
+    std::string_view value;
 
 public:
     attr(std::initializer_list<std::string_view> l) {

include/spdlog/pattern_formatter-inl.h

@@ -1010,6 +1010,16 @@ public:
         }
         // fmt_helper::append_string_view(msg.msg(), dest);
         fmt_helper::append_string_view(msg.payload, dest);
+
+        if (msg.attributes.size() > 0) {
+            fmt_helper::append_string_view(" | ", dest);
+            for (const details::attr& a : msg.attributes) {
+                fmt_helper::append_string_view(a.key, dest);
+                fmt_helper::append_string_view("=\"", dest);
+                fmt_helper::append_string_view(a.value, dest);
+                fmt_helper::append_string_view("\", ", dest);
+            }
+        }
     }
 
 private: