I am out of town and was compiling hREA via nix-shell on my old 4 core laptop with the 4Gb of memory and a 2Gb tmpfs in-memory filesystem and got the “Out of file space” errors deep into the compile. It took sudo mount -o remount,size=6G,noatime /tmp (use temporarily - will reset at reboot) to get it all the way up to 6Gb to get the compile to complete. It used to take an hour, but now I think it takes over 2 hours because of all the disk IO. At any rate it is possible so use it if you are in a pinch. I am interested of course if there are Rust flags that could be set to improve this situation like keeping the in process binaries so you didn’t have to start over on an error. I enabled the nix caching too I thought, but maybe something is wrong there.