message: Switch to -print-resource-dir (drop support for system clang 4.0)
diff: @@ -99,23 +99,9 @@ endif()
  _Clang_find_program(Clang_EXECUTABLE clang)
  if(Clang_EXECUTABLE)
  # Find Clang resource directory with Clang executable
  - # TODO: simplify by using -print-resource-dir once Clang 4 support is dropped
  - if(${CMAKE_SYSTEM_NAME} STREQUAL Windows)
  - set(_DEV_NULL NUL)
  - else()
  - set(_DEV_NULL /dev/null)
  - endif()
  -
  - # clang "-###" -xc /dev/null
  - execute_process(COMMAND ${Clang_EXECUTABLE} "-###" -xc ${_DEV_NULL}
  - ERROR_VARIABLE Clang_RESOURCE_DIR OUTPUT_QUIET)
  - # Strip everything except '"-resource-dir" "<resource-dir-path>"'
  - string(REGEX MATCH "\"-resource-dir\" \"([^\"]*)\""
  - Clang_RESOURCE_DIR ${Clang_RESOURCE_DIR})
  - # Strip quotes
  - string(REPLACE "\"" "" Clang_RESOURCE_DIR ${Clang_RESOURCE_DIR})
  - # Strip '-resource-dir '
  - string(REPLACE "-resource-dir " "" Clang_RESOURCE_DIR ${Clang_RESOURCE_DIR})
  + execute_process(COMMAND ${Clang_EXECUTABLE} -print-resource-dir
  + OUTPUT_VARIABLE Clang_RESOURCE_DIR
  + OUTPUT_STRIP_TRAILING_WHITESPACE)
  # Find Clang version
  set(_Clang_VERSION_REGEX "([0-9]+)\\.([0-9]+)\\.([0-9]+)")
  