From 84cdb09a5b0b8bc128d7ecee9a452511eba579d3 Mon Sep 17 00:00:00 2001
From: scawful <justin.scofield@outlook.com>
Date: Thu, 20 Nov 2025 02:42:02 -0500
Subject: [PATCH] fix(windows): improve clang-cl detection with multiple
 fallback methods

Enhanced clang-cl detection to use three methods in priority order:
1. CMAKE_CXX_SIMULATE_ID == "MSVC" (most reliable, set when compiler simulates MSVC)
2. CMAKE_CXX_COMPILER_FRONTEND_VARIANT == "MSVC" (CMake 3.14+)
3. Compiler executable name matches "clang-cl"

This triple-fallback approach ensures we correctly identify clang-cl even if
CMake variables aren't set as expected in GitHub Actions environment.

Previous attempt may have failed because CMAKE_CXX_COMPILER_FRONTEND_VARIANT
wasn't available or set. CMAKE_CXX_SIMULATE_ID is the canonical way to detect
when a compiler is simulating another compiler's interface.

The /std:c++latest flag is critical for clang-cl to access std::filesystem
from MSVC STL instead of falling back to std::experimental::filesystem.

Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>
---
 src/util/util.cmake | 39 +++++++++++++++++++++++++++++----------
 1 file changed, 29 insertions(+), 10 deletions(-)

diff --git a/src/util/util.cmake b/src/util/util.cmake
index f4ba062e..688df956 100644
--- a/src/util/util.cmake
+++ b/src/util/util.cmake
@@ -110,16 +110,35 @@ elseif(WIN32)
   # clang-cl uses Clang's compiler but must interface with MSVC STL. Without this flag,
   # it only finds std::experimental::filesystem (pre-C++17 version).
   #
-  # The CMAKE_CXX_COMPILER_FRONTEND_VARIANT check distinguishes:
-  # - "MSVC": clang-cl (Clang with MSVC-compatible command line)
-  # - "GNU": regular Clang on Windows
-  if(CMAKE_CXX_COMPILER_ID MATCHES "Clang" AND CMAKE_CXX_COMPILER_FRONTEND_VARIANT STREQUAL "MSVC")
-    # Use MSVC-style flag for clang-cl
-    target_compile_options(yaze_util PUBLIC /std:c++latest)
-    message(STATUS "Windows clang-cl detected: Added /std:c++latest for std::filesystem support")
-  elseif(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
-    # Regular Clang on Windows - already has proper flags from parent
-    message(STATUS "Windows Clang (non-cl) detected: Using inherited C++23 flags")
+  # Detection strategy:
+  # 1. Check CMAKE_CXX_SIMULATE_ID == "MSVC" (set when compiler simulates MSVC)
+  # 2. Or check CMAKE_CXX_COMPILER_FRONTEND_VARIANT == "MSVC" (CMake 3.14+)
+  # 3. Or check compiler executable name contains "clang-cl"
+
+  set(IS_CLANG_CL FALSE)
+
+  if(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
+    # Method 1: CMAKE_CXX_SIMULATE_ID is most reliable
+    if(CMAKE_CXX_SIMULATE_ID STREQUAL "MSVC")
+      set(IS_CLANG_CL TRUE)
+      message(STATUS "Detected clang-cl via CMAKE_CXX_SIMULATE_ID=MSVC")
+    # Method 2: CMAKE_CXX_COMPILER_FRONTEND_VARIANT (CMake 3.14+)
+    elseif(DEFINED CMAKE_CXX_COMPILER_FRONTEND_VARIANT AND CMAKE_CXX_COMPILER_FRONTEND_VARIANT STREQUAL "MSVC")
+      set(IS_CLANG_CL TRUE)
+      message(STATUS "Detected clang-cl via CMAKE_CXX_COMPILER_FRONTEND_VARIANT=MSVC")
+    # Method 3: Check executable name
+    elseif(CMAKE_CXX_COMPILER MATCHES "clang-cl")
+      set(IS_CLANG_CL TRUE)
+      message(STATUS "Detected clang-cl via compiler executable name")
+    endif()
+
+    if(IS_CLANG_CL)
+      # Use MSVC-style /std:c++latest flag for clang-cl
+      target_compile_options(yaze_util PUBLIC /std:c++latest)
+      message(STATUS "Applied /std:c++latest to yaze_util for std::filesystem support")
+    else()
+      message(STATUS "Regular Clang on Windows detected, using inherited C++23 flags")
+    endif()
   endif()
 endif()