message: VSO#756601 is fixed in 16.2
diff: @@ -213,6 +213,8 @@ namespace ranges
  #define RANGES_CXX_VER _MSVC_LANG
  #if _MSC_VER < 1922
  +#define RANGES_WORKAROUND_MSVC_756601 // constexpr friend non-template erroneously rejected
  + // with C3615
  #define RANGES_WORKAROUND_MSVC_793042 // T[0] sometimes accepted as a valid type in SFINAE
  // context
  @@ -257,8 +259,6 @@ namespace ranges
  // for pointer-to-array i
  #define RANGES_WORKAROUND_MSVC_688606 // SFINAE failing to account for access control
  // during specialization matching
  -#define RANGES_WORKAROUND_MSVC_756601 // constexpr friend non-template erroneously
  - // rejected with C3615
  #define RANGES_WORKAROUND_MSVC_779708 // ADL for operands of function type [No workaround]
  #define RANGES_WORKAROUND_MSVC_786312 // Yet another mixed-pack-expansion failure
  #define RANGES_WORKAROUND_MSVC_792338 // Failure to match specialization enabled via call
  