Move clang-cl detection to cmake and allow it when setting flags

CMakeLists.txt

@@ -1,4 +1,12 @@
 cmake_minimum_required(VERSION 3.18)
+
+if(MSVC AND ENV{CC} MATCHES ".*clang-cl.*")
+    set(CMAKE_GENERATOR_TOOLSET "ClangCL")
+    set(CLANG_CL TRUE)
+else()
+    set(CLANG_CL FALSE)
+endif()
+
 include(tools/CompilerWarnings.cmake)
 include(tools/CPUFeatures.cmake)
 set(CMAKE_VERBOSE_MAKEFILE ON)

pyproject.toml

@@ -78,7 +78,7 @@ archs = ["auto64"] # arm64 windows builds not yet supported
 test-command = "cd /d {project} && python -m unittest --verbose" # windows why is this flag required
 # MSVC compiled wheels will just have to be serial ops until distutil supports clang-cl
 # https://github.com/python/cpython/pull/18371
-environment = { CXX = "clang-cl.exe", CC = "clang-cl.exe" }
+environment = { QUICKTEX_HWY_MODE = "SSE4", CXX = "clang-cl.exe", CC = "clang-cl.exe" }
 
 [tool.cibuildwheel.linux]
 skip = ["cp37-musllinux*", "*musllinux_aarch64*"] # skip targets without available Pillow wheels

setup.py

@@ -66,8 +66,8 @@ class CMakeBuild(build_ext):
                 cmake_args += ["-GNinja"]
 
         else:
-            if 'CC' in os.environ and 'clang-cl' in os.environ['CC']:
-                cmake_args += ["-T", 'ClangCL']  # https://stackoverflow.com/a/64189112/7645957
+            # if 'CC' in os.environ and 'clang-cl' in os.environ['CC']:
+            #     cmake_args += ["-T", 'ClangCL']  # https://stackoverflow.com/a/64189112/7645957
 
             # Single config generators are handled "normally"
             single_config = any(x in cmake_generator for x in {"NMake", "Ninja"})

tools/CPUFeatures.cmake

@@ -42,20 +42,32 @@ function(set_simd_flags target_name)
         if (highway_mode STREQUAL "AUTO")
             # setting -march=native on an M1 causes Clang to freak out
             if (MSVC)
-                #MSVC has no -march=native equivalent. womp
-                message(WARNING "Compiling using MSVC without settig an explicit QUICKTEX_HWY_MODE defaults to serial operations. Please compile with Clang if you need vectorization")
+                if (CLANG_CL)
+                    target_compile_options(${target_name} PUBLIC /clang:-march=native)
+                else()
+                    #MSVC has no -march=native equivalent. womp
+                    message(WARNING "Compiling using cl.exe without settig an explicit QUICKTEX_HWY_MODE defaults to serial operations. Please compile with clang-cl if you need vectorization")
+                endif()
             elseif (!ARM)
                 target_compile_options(${target_name} PUBLIC -march=native)
             endif ()
         elseif (highway_mode STREQUAL "SSSE3")
             if (MSVC)
-                message(SEND_ERROR "Compiling using SSSE3 is not supported with the MSVC compiler. Please use AVX or compile withClang")
+                if (CLANG_CL)
+                    target_compile_options(${target_name} PUBLIC /clang:-mssse3)
+                else()
+                    message(SEND_ERROR "Compiling using SSSE3 is not supported with the cl.exe compiler. Please use AVX or compile with clang-cl")
+                endif()
             else ()
                 target_compile_options(${target_name} PUBLIC -mssse3)
             endif ()
         elseif (highway_mode STREQUAL "SSE4")
             if (MSVC)
-                message(SEND_ERROR "Compiling using SSE4 is not supported with the MSVC compiler. Please use AVX or compile with Clang")
+                if (CLANG_CL)
+                    target_compile_options(${target_name} PUBLIC /clang:-msse4)
+                else()
+                    message(SEND_ERROR "Compiling using SSE4 is not supported with the MSVC compiler. Please use AVX or compile with Clang")
+                endif()
             else ()
                 target_compile_options(${target_name} PUBLIC -msse4)
             endif ()