Retire clang_version (#451)

* Retire clang_version

Note: this makes the "install" target install the compiler rt
into the compiler's runtime directory.  IMO, it's what "install" is
supposed to do.  If you want to avoid modifing the runtime directory
for some reasons, you can still do "dist" without "install".

* wasi-sdk-sysroot.cmake: Avoid modifying things out of CMAKE_INSTALL_PREFIX

* wasi-sdk-sysroot.cmake: control the resource-dir modification by a cmake option

CMakeLists.txt

@@ -24,16 +24,11 @@ find_program(PYTHON python3 python REQUIRED)
 
 # Set some variables based on the `version.py` script
 set(version_script ${CMAKE_CURRENT_SOURCE_DIR}/version.py)
-execute_process(
-  COMMAND ${PYTHON} ${version_script} llvm-major --llvm-dir=${llvm_proj_dir}
-  OUTPUT_VARIABLE clang_version
-  OUTPUT_STRIP_TRAILING_WHITESPACE)
 execute_process(
   COMMAND ${PYTHON} ${version_script}
   OUTPUT_VARIABLE wasi_sdk_version
   OUTPUT_STRIP_TRAILING_WHITESPACE)
 
-message(STATUS "wasi-sdk toolchain LLVM version is ${clang_version}")
 message(STATUS "wasi-sdk version is ${wasi_sdk_version}")
 
 # Only include one version of the build logic as pulling in both isn't

cmake/wasi-sdk-sysroot.cmake

@@ -9,10 +9,11 @@ find_program(MAKE make REQUIRED)
 
 option(WASI_SDK_DEBUG_PREFIX_MAP "Pass `-fdebug-prefix-map` for built artifacts" ON)
 option(WASI_SDK_INCLUDE_TESTS "Whether or not to build tests by default" OFF)
+option(WASI_SDK_INSTALL_TO_CLANG_RESOURCE_DIR "Whether or not to modify the compiler's resource directory" OFF)
 
 set(wasi_tmp_install ${CMAKE_CURRENT_BINARY_DIR}/install)
 set(wasi_sysroot ${wasi_tmp_install}/share/wasi-sysroot)
-set(wasi_resource_dir ${wasi_tmp_install}/lib/clang/${clang_version})
+set(wasi_resource_dir ${wasi_tmp_install}/wasi-resource-dir)
 
 if(WASI_SDK_DEBUG_PREFIX_MAP)
   add_compile_options(
@@ -246,9 +247,18 @@ endforeach()
 # misc build logic
 # =============================================================================
 
-install(DIRECTORY ${wasi_tmp_install}/lib ${wasi_tmp_install}/share
+install(DIRECTORY ${wasi_tmp_install}/share
         USE_SOURCE_PERMISSIONS
         DESTINATION ${CMAKE_INSTALL_PREFIX})
+if(WASI_SDK_INSTALL_TO_CLANG_RESOURCE_DIR)
+  install(DIRECTORY ${wasi_resource_dir}/lib
+          USE_SOURCE_PERMISSIONS
+          DESTINATION ${clang_resource_dir})
+else()
+  install(DIRECTORY ${wasi_resource_dir}/lib
+          USE_SOURCE_PERMISSIONS
+          DESTINATION ${CMAKE_INSTALL_PREFIX}/clang-resource-dir)
+endif()
 
 # Add a top-level `build` target as well as `build-$target` targets.
 add_custom_target(build ALL)
@@ -282,7 +292,7 @@ set(dist_dir ${CMAKE_CURRENT_BINARY_DIR}/dist)
 # Tarball with just `compiler-rt` builtins within it
 wasi_sdk_add_tarball(dist-compiler-rt
   ${dist_dir}/libclang_rt.builtins-wasm32-wasi-${wasi_sdk_version}.tar.gz
-  ${wasi_tmp_install}/lib/clang/${clang_version}/lib/wasi)
+  ${wasi_resource_dir}/lib/wasi)
 add_dependencies(dist-compiler-rt compiler-rt)
 
 # Tarball with the whole sysroot