wrappers: add CMake toolchain files

Those toolchain files greatly simplify configuring a project
to use the llvm-mingw toolchain.

install-wrappers.sh

@@ -141,6 +141,12 @@ if [ -n "$EXEEXT" ]; then
 else
     CTW_SUFFIX=.sh
 fi
+toolchainfile_path=share/cmake; toolchainfile_rev=../..
+mkdir -p "$PREFIX/$toolchainfile_path"
+sed "s,@RELPATH@,$toolchainfile_rev,g" wrappers/llvm-mingw_toolchainfile.cmake.in >"$PREFIX/$toolchainfile_path/llvm-mingw_toolchainfile.cmake"
+for arch in $ARCHS; do
+    sed "s,@ARCH@,${arch},g" wrappers/llvm-mingw_toolchainfile_arch.cmake.in >"$PREFIX/$toolchainfile_path/${arch}-w64-mingw32_toolchainfile.cmake"
+done
 cd "$PREFIX/bin"
 for arch in $ARCHS; do
     for target_os in $TARGET_OSES; do

wrappers/llvm-mingw_toolchainfile.cmake.in

@@ -0,0 +1,84 @@
+if(CMAKE_VERSION VERSION_GREATER_EQUAL "3.20")
+  set(_prefix "${CMAKE_CURRENT_LIST_DIR}/@RELPATH@/")
+  cmake_path(ABSOLUTE_PATH _prefix NORMALIZE)
+else()
+  get_filename_component(_prefix "${CMAKE_CURRENT_LIST_DIR}/@RELPATH@/" ABSOLUTE)
+endif()
+
+if(NOT CMAKE_SYSTEM_NAME AND NOT CMAKE_HOST_WIN32)
+  set(CMAKE_SYSTEM_NAME Windows)
+endif()
+if(NOT CMAKE_SYSTEM_PROCESSOR)
+  set(CMAKE_SYSTEM_PROCESSOR ${CMAKE_HOST_SYSTEM_PROCESSOR})
+  if(CMAKE_HOST_WIN32)
+    if(CMAKE_SYSTEM_PROCESSOR STREQUAL "ARM64")
+      set(CMAKE_SYSTEM_PROCESSOR aarch64)
+    elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "^ARM")
+      set(CMAKE_SYSTEM_PROCESSOR armv7)
+    elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "^[Xx]86$")
+      set(CMAKE_SYSTEM_PROCESSOR i686)
+    elseif(CMAKE_SYSTEM_PROCESSOR STREQUAL "AMD64" OR CMAKE_SYSTEM_PROCESSOR MATCHES "^[Xx]64$")
+      set(CMAKE_SYSTEM_PROCESSOR x86_64)
+    endif()
+  endif()
+endif()
+
+set(CMAKE_SYSROOT "${_prefix}${CMAKE_SYSTEM_PROCESSOR}-w64-mingw32")
+
+if(NOT "$ENV{PKG_CONFIG_LIBDIR}" STREQUAL "")
+  set(_respath "${CMAKE_SYSROOT}/lib/pkgconfig:${CMAKE_SYSROOT}/share/pkgconfig:$ENV{PKG_CONFIG_LIBDIR}")
+else()
+  set(_respath "${CMAKE_SYSROOT}/lib/pkgconfig:${CMAKE_SYSROOT}/share/pkgconfig")
+endif()
+
+if(CMAKE_VERSION VERSION_GREATER_EQUAL "3.20")
+  cmake_path(CONVERT _respath TO_NATIVE_PATH_LIST _respath)
+  set(ENV{PKG_CONFIG_LIBDIR} "${_respath}")
+  cmake_path(NATIVE_PATH CMAKE_SYSROOT _respath)
+  set(ENV{PKG_CONFIG_SYSROOT_DIR} "${_respath}")
+else()
+  file(TO_NATIVE_PATH "${_respath}" _respath)
+  set(ENV{PKG_CONFIG_LIBDIR} "${_respath}")
+  file(TO_NATIVE_PATH "${CMAKE_SYSROOT}" _respath)
+  set(ENV{PKG_CONFIG_SYSROOT_DIR} "${_respath}")
+endif()
+
+# set these before find_program!
+set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)
+
+set(_linker lld)
+set(_exesuff)
+if(CMAKE_HOST_WIN32)
+set(_exesuff .exe)
+endif()
+set(CMAKE_ASM_COMPILER "${_prefix}bin/clang${_exesuff}")
+set(CMAKE_C_COMPILER "${_prefix}bin/clang${_exesuff}")
+set(CMAKE_CXX_COMPILER "${_prefix}bin/clang++${_exesuff}")
+set(CMAKE_RC_COMPILER "${_prefix}bin/llvm-rc${_exesuff}")
+set(CMAKE_LINKER "${_prefix}bin/ld.${_linker}${_exesuff}")
+unset(_exesuff)
+
+unset(_prefix)
+unset(_respath)
+
+set(CMAKE_C_COMPILER_TARGET ${CMAKE_SYSTEM_PROCESSOR}-w64-mingw32)
+set(CMAKE_CXX_COMPILER_TARGET ${CMAKE_C_COMPILER_TARGET})
+set(CMAKE_ASM_COMPILER_TARGET ${CMAKE_C_COMPILER_TARGET})
+
+set(CMAKE_CXX_FLAGS_INIT "-stdlib=libc++")
+
+if(CMAKE_VERSION VERSION_GREATER_EQUAL "3.29")
+  string(TOUPPER ${_linker} CMAKE_LINKER_TYPE)
+  set(_linker)
+else()
+  set(_linker " -fuse-ld=${_linker}")
+endif()
+
+# CMAKE_CXX_FLAGS is automatically added now, but might be needed to add -stdlib=libc++ for really old CMake Versions
+set(CMAKE_EXE_LINKER_FLAGS_INIT "--start-no-unused-arguments -rtlib=compiler-rt -unwindlib=libunwind --end-no-unused-arguments${_linker}")
+set(CMAKE_MODULE_LINKER_FLAGS_INIT "${CMAKE_EXE_LINKER_FLAGS_INIT}")
+set(CMAKE_SHARED_LINKER_FLAGS_INIT "${CMAKE_EXE_LINKER_FLAGS_INIT}")
+unset(_linker)

wrappers/llvm-mingw_toolchainfile_arch.cmake.in

@@ -0,0 +1,7 @@
+if(NOT CMAKE_SYSTEM_NAME)
+  set(CMAKE_SYSTEM_NAME Windows)
+endif()
+
+set(CMAKE_SYSTEM_PROCESSOR @ARCH@)
+
+include("${CMAKE_CURRENT_LIST_DIR}/llvm-mingw_toolchainfile.cmake")