[Compiler-rt] Broken compiler-rt CMake configuring on Windows

[iid_iunknown]

Summary

Hi Michal,

Would you be able to review this simple fix, please?

Since r291504 compiler-rt uses llvm-config --cmakedir to get the path to the LLVM CMake modules.
On Windows this option returns Windows style path with backslashes. CMake treats backslashes as beginning of an escaped character and thus fails to append the path to CMAKE_MODULE_PATH.

[mgorny]

@compnerd, could you share your Windows knowledge? ;-)

[mgorny]

Well, it doesn't seem to break anything for me on Linux and it resembles the code below, so I guess it's good to go.

[iid_iunknown]

In D28908#656573, @mgorny wrote:

Well, it doesn't seem to break anything for me on Linux and it resembles the code below, so I guess it's good to go.

Yes, the patch just guarantees that the path is in the proper format for cmake, and leaves the path untouched if it is ok (which is currently the case for any non-Windows platform).

Thanks for reviewing this!

cmake/Modules/CompilerRTUtils.cmake

macro(load_llvm_config)
 
   # Make use of LLVM CMake modules.
   # --cmakedir is supported since llvm r291218 (4.0 release)
   execute_process(
     COMMAND ${LLVM_CONFIG_PATH} --cmakedir
     RESULT_VARIABLE HAD_ERROR
     OUTPUT_VARIABLE CONFIG_OUTPUT)
   if(NOT HAD_ERROR)
-    string(STRIP "${CONFIG_OUTPUT}" LLVM_CMAKE_PATH)
+    string(STRIP "${CONFIG_OUTPUT}" LLVM_CMAKE_PATH_FROM_LLVM_CONFIG)
+    file(TO_CMAKE_PATH ${LLVM_CMAKE_PATH_FROM_LLVM_CONFIG} LLVM_CMAKE_PATH)
   else()
     file(TO_CMAKE_PATH ${LLVM_BINARY_DIR} LLVM_BINARY_DIR_CMAKE_STYLE)
     set(LLVM_CMAKE_PATH "${LLVM_BINARY_DIR_CMAKE_STYLE}/lib${LLVM_LIBDIR_SUFFIX}/cmake/llvm")
   endif()
 
   list(APPEND CMAKE_MODULE_PATH "${LLVM_CMAKE_PATH}")
   # Get some LLVM variables from LLVMConfig.
   include("${LLVM_CMAKE_PATH}/LLVMConfig.cmake")