From ff28310f56463078377329cf1bf6599297f401b1 Mon Sep 17 00:00:00 2001
From: Luohao Wang <luohaothu@live.com>
Date: Wed, 4 Feb 2026 21:38:52 +0800
Subject: [PATCH] Upgrade to C++26 and enable -Wall -Werror

- Bump C++ standard from C++23 to C++26 in CMakeLists.txt
- Enable -Wall and -Werror compiler flags for stricter builds
- Foundation for comprehensive warning fixes in follow-up PRs

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
---
 src/CMakeLists.txt | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index f2b555c5..451dbea5 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -42,11 +42,11 @@ if(OPFLOW_ENABLE_MODULE)
         FILE_SET HEADERS DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
 else()
     # ----------------------------------------------------------------------------
-    # C++20 header only version
+    # C++26 header only version
     # ----------------------------------------------------------------------------
     add_library(opflow INTERFACE)
     set_property(TARGET opflow PROPERTY CXX_SCAN_FOR_MODULES OFF)
-    target_compile_features(opflow INTERFACE cxx_std_20)
+    target_compile_features(opflow INTERFACE cxx_std_26)
     target_sources(opflow
         INTERFACE FILE_SET HEADERS ${OPFLOW_HEADERS})
     install(TARGETS opflow
@@ -116,3 +116,23 @@ target_link_options(opflow
     INTERFACE $<$<BOOL:${OPFLOW_SANITIZE_LEAK}>: -fsanitize=leak>
     INTERFACE $<$<BOOL:${OPFLOW_SANITIZE_THREAD}>: -fsanitize=thread>
     INTERFACE $<$<BOOL:${OPFLOW_SANITIZE_UB}>: -fsanitize=undefined>)
+
+# ----------------------------------------------------------------------------
+# Compiler warnings
+# ----------------------------------------------------------------------------
+# Enable strict warnings and treat warnings as errors by default
+
+if(CMAKE_CXX_COMPILER_ID MATCHES "GNU" OR CMAKE_CXX_COMPILER_ID MATCHES "Clang")
+    target_compile_options(opflow ${OPFLOW_TARGET_SCOPE}
+        -Wall
+        -Wextra
+        -Werror
+    )
+endif()
+# MSVC-specific warnings
+if(MSVC)
+    target_compile_options(opflow ${OPFLOW_TARGET_SCOPE}
+        /W4
+        /WX
+    )
+endif()