From 4bb1540d1d75db41040ad66c8d656a913728bee1 Mon Sep 17 00:00:00 2001
From: Mark Schofield <34426337+MarkSchofield@users.noreply.github.com>
Date: Fri, 28 Aug 2026 09:35:24 -0700
Subject: [PATCH] Accommodate a clang hint-path

---
 Windows.Clang.toolchain.cmake | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/Windows.Clang.toolchain.cmake b/Windows.Clang.toolchain.cmake
index bba0a68..5a55483 100644
--- a/Windows.Clang.toolchain.cmake
+++ b/Windows.Clang.toolchain.cmake
@@ -39,6 +39,7 @@
 # | CMAKE_VS_VERSION_RANGE                      | A verson range for VS instances to find. For example, '[16.0,17.0)' will find versions '16.*'. Defaults to '[16.0,17.0)' |
 # | CMAKE_WINDOWS_KITS_10_DIR                   | The location of the root of the Windows Kits 10 directory.                                                               |
 # | TOOLCHAIN_ADD_VS_NINJA_PATH                 | Whether the toolchain should add the path to the VS Ninja to the CMAKE_SYSTEM_PROGRAM_PATH. Defaults to 'ON'.            |
+# | TOOLCHAIN_LLVM_HINT_PATH                    | A 'hint path' to LLVM. If set, it will be used to find clang/clang-cl in the 'bin' folder.                               |
 # | TOOLCHAIN_UPDATE_PROGRAM_PATH               | Whether the toolchain should update CMAKE_PROGRAM_PATH. Defaults to 'ON'.                                                |
 # | VS_INSTALLATION_PATH                        | The location of the root of the Visual Studio installation. If not specified VSWhere will be used to search for one.     |
 #
@@ -226,13 +227,24 @@ unset(TOOLCHAIN_TARGET)
 
 # Look for clang/clang-cl.
 #
-# The Visual Studio-distributed clang tools are preferred, followed by the default installation location.
-set(TOOLCHAIN_CLANG_HINTS_PATHS "$ENV{ProgramFiles}/LLVM/bin")
-list(PREPEND TOOLCHAIN_CLANG_HINTS_PATHS "${VS_INSTALLATION_PATH}/VC/Tools/Llvm/x64/bin")
+# The following paths are considered in order:
+#   1) 'TOOLCHAIN_LLVM_HINT_PATH' if set.
+#   2) '${VS_INSTALLATION_PATH}/VC/Tools/Llvm/arm64' if the host is ARM64.
+#   3) '${VS_INSTALLATION_PATH}/VC/Tools/Llvm/x64'.
+#   4) '$ENV{ProgramFiles}/LLVM'
+#
+set(TOOLCHAIN_CLANG_HINTS_PATHS)
+if(TOOLCHAIN_LLVM_HINT_PATH)
+    list(APPEND TOOLCHAIN_CLANG_HINTS_PATHS "${TOOLCHAIN_LLVM_HINT_PATH}/bin")
+endif()
+
 if(CMAKE_HOST_SYSTEM_PROCESSOR STREQUAL ARM64)
-    list(PREPEND TOOLCHAIN_CLANG_HINTS_PATHS "${VS_INSTALLATION_PATH}/VC/Tools/Llvm/arm64/bin")
+    list(APPEND TOOLCHAIN_CLANG_HINTS_PATHS "${VS_INSTALLATION_PATH}/VC/Tools/Llvm/arm64/bin")
 endif()
 
+list(APPEND TOOLCHAIN_CLANG_HINTS_PATHS "${VS_INSTALLATION_PATH}/VC/Tools/Llvm/x64/bin")
+list(APPEND TOOLCHAIN_CLANG_HINTS_PATHS "$ENV{ProgramFiles}/LLVM/bin")
+
 if(NOT CMAKE_C_COMPILER)
     set(TOOLCHAIN_C_COMPILER_EXE clang.exe)
     if(CMAKE_C_COMPILER_FRONTEND_VARIANT STREQUAL MSVC)