We’ve been making a lot of changes to HDF4 to bring it, kicking and screaming, into the 2020s. We’ve been particularly keen to get it working on ARM processors, including Apple’s M1 and M2 platforms. Feedback regarding MinGW and Cygwin would also be very helpful. Fortran feedback is also much desired. And if you are using an OS other than what we test on GitHub (e.g., BSDs, Solaris, AIX), we would really like to hear from you. We replaced most of the hard-coded, machine-specific setup with configure checks and C99 types and I’d like to make sure we didn’t break anything on platforms we can’t easily test.
Things are still a work in progress, but any feedback we could get from the community would be incredibly useful. The 4.2.16 release is scheduled for the end of January, so there’s still time to get changes in.
If you have feedback, you can either add it here or create an issue on GitHub.