From 2bd3f39e72c4b616eac6e0706b0972636ca8a769 Mon Sep 17 00:00:00 2001
From: Tom Tan <totan@microsoft.com>
Date: Mon, 10 Mar 2025 17:34:02 -0700
Subject: [PATCH 1/2] Change the param-pack unpacking order to start from left
 to right

---
 api/include/opentelemetry/logs/logger.h | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/api/include/opentelemetry/logs/logger.h b/api/include/opentelemetry/logs/logger.h
index 519516f297..4ad906d002 100644
--- a/api/include/opentelemetry/logs/logger.h
+++ b/api/include/opentelemetry/logs/logger.h
@@ -72,8 +72,16 @@ class Logger
       return;
     }
 
-    IgnoreTraitResult(detail::LogRecordSetterTrait<typename std::decay<ArgumentType>::type>::Set(
-        log_record.get(), std::forward<ArgumentType>(args))...);
+    //
+    // Keep the parameter pack unpacking order from left to right because left
+    // ones are usually more important like severity and event_id than the
+    // attributes. The left to right unpack order could pass the more important
+    // data to processors to avoid caching and memory allocating.
+    //
+    IgnoreTraitResult(
+      (detail::LogRecordSetterTrait<typename std::decay<ArgumentType>::type>::Set(
+        log_record.get(),
+        std::forward<ArgumentType>(args)),...));
 
     EmitLogRecord(std::move(log_record));
   }

From dc03d427350ebf1eea8a4d69e7309085aee4582c Mon Sep 17 00:00:00 2001
From: Tom Tan <totan@microsoft.com>
Date: Mon, 10 Mar 2025 18:41:48 -0700
Subject: [PATCH 2/2] Add fallback for c++14 and below

---
 api/include/opentelemetry/logs/logger.h | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/api/include/opentelemetry/logs/logger.h b/api/include/opentelemetry/logs/logger.h
index 4ad906d002..6bc78f857a 100644
--- a/api/include/opentelemetry/logs/logger.h
+++ b/api/include/opentelemetry/logs/logger.h
@@ -78,10 +78,17 @@ class Logger
     // attributes. The left to right unpack order could pass the more important
     // data to processors to avoid caching and memory allocating.
     //
-    IgnoreTraitResult(
-      (detail::LogRecordSetterTrait<typename std::decay<ArgumentType>::type>::Set(
-        log_record.get(),
-        std::forward<ArgumentType>(args)),...));
+#if __cplusplus <= 201402L
+    // C++14 does not support fold expressions for parameter pack expansion.
+    int dummy[] = {(detail::LogRecordSetterTrait<typename std::decay<ArgumentType>::type>::Set(
+                        log_record.get(), std::forward<ArgumentType>(args)),
+                    0)...};
+    IgnoreTraitResult(dummy);
+#else
+    IgnoreTraitResult((detail::LogRecordSetterTrait<typename std::decay<ArgumentType>::type>::Set(
+                           log_record.get(), std::forward<ArgumentType>(args)),
+                       ...));
+#endif
 
     EmitLogRecord(std::move(log_record));
   }