On 17/04/2023 14:33, Dominique Pellé via Boost-users wrote:

Hi

1) Compiling the attached "brands.cpp" file which uses boost::container::flat_set is very slow with clang when using boost-1.81.0. It was much faster with boost-1.80.0 somehow.

Thanks for reporting this. Peter Dimov looked into this and found that the cause is recently added use of __forceinline. A suitable workaround until the next Boost release is -DBOOST_CONTAINER_DISABLE_FORCEINLINE I can't speak for Ion, but I'd assume it'll be fixed next Boost release. Once again thanks for reporting this, it wasn't noticed by the usual release testing. Niall