Hello everyone, As you may know, GHC carries a dependency on the libffi library. Libffi is used on most platforms (notably not x86 and x86-64) for foreign function invocation (see rts/Adjustor.c for details). While libffi works well, it is unfortunately not particularly actively maintained. In fact, it has been nearly three years since the last official release. A lot can happen in three years and there is now at least two bugs [1,2] present in the current release which makes it impossible to build GHC in some configurations. These bugs have been fixed upstream but these fixes are unreleased. Numerous attempts have been made to get the libffi maintainers to cut a new release but sadly no progress has been made in over six months of trying. In light of this I propose that we begin treating libffi as a submodule until a release is made. In particular, adding libffi as a submodule will ease development on ARM and AArch64 (especially Apple) targets, which have seen quite a bit of developer attention recently. Note that under this scheme it will still be possible to link against the system's libffi installation using ./configure's --enable-system-libffi flag. Are there any strong objections to plan? If so please speak up. If there is no objection by Saturday we will move ahead. Cheers, - Ben [1] https://github.com/libffi/libffi/issues/191 [2] https://github.com/libffi/libffi/pull/263