Here are the known bugs in MLton 20210117, listed in reverse chronological order of date reported.
Bug with amd64 and LLVM codegens calling C functions with signed 8-bit and 16-bit arguments.
Fixed by commits 286a54cc0 and c4502bdfb.
286a54cc0
c4502bdfb
Bug with -profile time leading to a segmentation fault.
-profile time
Thanks to Byron Zhong for the bug report.
Fixed by commit 737a4b6e0.
737a4b6e0