[libcxxabi] [CMake] Convert paths to the right form in standalone builds on Windows

[mstorsjo]

Summary

The paths output from llvm-config --cmakedir and from clang --print-libgcc-file-name can contain backslashes, while CMake can't handle the paths in this form.

This matches what compiler-rt already does (since SVN r203789 and r293195).

[smeenai]

LGTM with the same comments as D48356 (add quotes, and is the translation for LLVM_BINARY_DIR necessary?)

libcxxabi/trunk/cmake/Modules/HandleCompilerRT.cmake

 function(find_compiler_rt_library name dest)
   if (NOT DEFINED LIBCXXABI_COMPILE_FLAGS)
     message(FATAL_ERROR "LIBCXXABI_COMPILE_FLAGS must be defined when using this function")
   endif()
   set(dest "" PARENT_SCOPE)
   set(CLANG_COMMAND ${CMAKE_CXX_COMPILER} ${LIBCXXABI_COMPILE_FLAGS}
       "--rtlib=compiler-rt" "--print-libgcc-file-name")
   if (CMAKE_CXX_COMPILER_ID MATCHES Clang AND CMAKE_CXX_COMPILER_TARGET)
     list(APPEND CLANG_COMMAND "--target=${CMAKE_CXX_COMPILER_TARGET}")
   endif()
   execute_process(
       COMMAND ${CLANG_COMMAND}
       RESULT_VARIABLE HAD_ERROR
       OUTPUT_VARIABLE LIBRARY_FILE
   )
   string(STRIP "${LIBRARY_FILE}" LIBRARY_FILE)
+  file(TO_CMAKE_PATH "${LIBRARY_FILE}" LIBRARY_FILE)
   string(REPLACE "builtins" "${name}" LIBRARY_FILE "${LIBRARY_FILE}")
   if (NOT HAD_ERROR AND EXISTS "${LIBRARY_FILE}")
     message(STATUS "Found compiler-rt library: ${LIBRARY_FILE}")
     set(${dest} "${LIBRARY_FILE}" PARENT_SCOPE)
   else()
     message(STATUS "Failed to find compiler-rt library")
   endif()
 endfunction()
 
 function(find_compiler_rt_dir dest)
   if (NOT DEFINED LIBCXXABI_COMPILE_FLAGS)
     message(FATAL_ERROR "LIBCXXABI_COMPILE_FLAGS must be defined when using this function")
   endif()
   set(dest "" PARENT_SCOPE)
   if (APPLE)
     set(CLANG_COMMAND ${CMAKE_CXX_COMPILER} ${LIBCXXABI_COMPILE_FLAGS}
         "-print-file-name=lib")
     execute_process(
         COMMAND ${CLANG_COMMAND}
         RESULT_VARIABLE HAD_ERROR
         OUTPUT_VARIABLE LIBRARY_DIR
     )
     string(STRIP "${LIBRARY_DIR}" LIBRARY_DIR)
+    file(TO_CMAKE_PATH "${LIBRARY_DIR}" LIBRARY_DIR)
     set(LIBRARY_DIR "${LIBRARY_DIR}/darwin")
   else()
     set(CLANG_COMMAND ${CMAKE_CXX_COMPILER} ${LIBCXXABI_COMPILE_FLAGS}
         "--rtlib=compiler-rt" "--print-libgcc-file-name")
     execute_process(
         COMMAND ${CLANG_COMMAND}
         RESULT_VARIABLE HAD_ERROR
         OUTPUT_VARIABLE LIBRARY_FILE
     )
     string(STRIP "${LIBRARY_FILE}" LIBRARY_FILE)
+    file(TO_CMAKE_PATH "${LIBRARY_FILE}" LIBRARY_FILE)
     get_filename_component(LIBRARY_DIR "${LIBRARY_FILE}" DIRECTORY)
   endif()
   if (NOT HAD_ERROR AND EXISTS "${LIBRARY_DIR}")
     message(STATUS "Found compiler-rt directory: ${LIBRARY_DIR}")
     set(${dest} "${LIBRARY_DIR}" PARENT_SCOPE)
   else()
     message(STATUS "Failed to find compiler-rt directory")
   endif()
 endfunction()

libcxxabi/trunk/cmake/Modules/HandleOutOfTreeLLVM.cmake

elseif(LLVM_CONFIG_PATH)
 
     # --cmakedir is supported since llvm r291218 (4.0 release)
     execute_process(
       COMMAND ${LLVM_CONFIG_PATH} --cmakedir
       RESULT_VARIABLE HAD_ERROR
       OUTPUT_VARIABLE CONFIG_OUTPUT
       ERROR_QUIET)
     if(NOT HAD_ERROR)
-      string(STRIP "${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()
-      set(LLVM_CMAKE_PATH
-          "${LLVM_BINARY_DIR}/lib${LLVM_LIBDIR_SUFFIX}/cmake/llvm")
+      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()
   else()
     set(LLVM_FOUND OFF)
     message(WARNING "UNSUPPORTED LIBCXXABI CONFIGURATION DETECTED: "
                     "llvm-config not found and LLVM_PATH not defined.\n"
                     "Reconfigure with -DLLVM_CONFIG_PATH=path/to/llvm-config "
                     "or -DLLVM_PATH=path/to/llvm-source-root.")
     return()