From 45b0d58f4fb25fa9ff3793b110d200b1d8e8f198 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Ho=C5=99e=C5=88ovsk=C3=BD?=
 <martin.horenovsky@gmail.com>
Date: Tue, 16 Jun 2026 11:16:54 +0200
Subject: [PATCH] Don't allocate string when translating error_code to msg

As the caller just appends the message into another `std::string`,
we can return `std::string_view` instead and save allocation.
---
 include/perfcpp/exception.hpp | 5 +++--
 src/exception.cpp             | 4 ++--
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/include/perfcpp/exception.hpp b/include/perfcpp/exception.hpp
index 3a06e99..052eb5f 100644
--- a/include/perfcpp/exception.hpp
+++ b/include/perfcpp/exception.hpp
@@ -3,6 +3,7 @@
 #include <cstdint>
 #include <stdexcept>
 #include <string>
+#include <string_view>
 
 namespace perf {
 
@@ -98,7 +99,7 @@ class CannotOpenCounterError final : public std::runtime_error
    * @param error_code Error code raised when calling perf_event_open.
    * @return Error message that can be thrown to inform the user.
    */
-  [[nodiscard]] static std::string create_error_message_from_code(std::int64_t error_code);
+  [[nodiscard]] static std::string_view create_error_message_from_code(std::int64_t error_code);
 };
 
 class CannotReadCounter final : public std::runtime_error
@@ -134,7 +135,7 @@ class IoctlError : public std::runtime_error
   ~IoctlError() override = default;
 
 protected:
-  [[nodiscard]] static std::string create_error_message_from_code(std::int64_t error_code);
+  [[nodiscard]] static std::string_view create_error_message_from_code(std::int64_t error_code);
 };
 
 class CannotEnableCounter final : public IoctlError
diff --git a/src/exception.cpp b/src/exception.cpp
index d0b782f..80cc85a 100644
--- a/src/exception.cpp
+++ b/src/exception.cpp
@@ -1,7 +1,7 @@
 #include <perfcpp/exception.hpp>
 #include <perfcpp/feature.h>
 
-std::string
+std::string_view
 perf::CannotOpenCounterError::create_error_message_from_code(const std::int64_t error_code)
 {
   switch (error_code) {
@@ -37,7 +37,7 @@ perf::CannotOpenCounterError::create_error_message_from_code(const std::int64_t
   }
 }
 
-std::string
+std::string_view
 perf::IoctlError::create_error_message_from_code(const std::int64_t error_code)
 {
   switch (error_code) {