Re: [Boost-users] boost/rational.hpp and VS2019

On 23/08/2021 18:12, John Maddock via Boost-users wrote:

I suspect you have a mangled platform header somewhere.

I found it !!! FWIW the problematic file (ammintrin.h) gets #included quite early in intrin.h like this:- #if (defined (_M_IX86) || defined (_M_X64)) && !defined(_CHPE_ONLY_) #include <immintrin.h> #include <ammintrin.h> #endif I checked 'immintin.h' and realised it was a zero length file! I then restored it from a recent backup and the problem's gone!! Many thanks John and Edward for all your help with this, John