message: turn off deduction guides on Apple's clang
diff: @@ -410,7 +410,10 @@ namespace ranges
  #endif // RANGES_CXX_INLINE_VARIABLES
  #ifndef RANGES_CXX_DEDUCTION_GUIDES
  -#ifdef __cpp_deduction_guides
  +#if defined(__clang__) && defined(__apple_build_version__)
  +// Apple's clang version doesn't do deduction guides very well.
  +#define RANGES_CXX_DEDUCTION_GUIDES 0
  +#elif defined(__cpp_deduction_guides)
  #define RANGES_CXX_DEDUCTION_GUIDES __cpp_deduction_guides
  #else
  #define RANGES_CXX_DEDUCTION_GUIDES RANGES_CXX_FEATURE(DEDUCTION_GUIDES)
  