nix-super/doc/manual/src/release-notes/rl-next.md

Release X.Y (202?-??-??)

• A new function builtins.readFileType is available. It is similar to builtins.readDir but acts on a single file or directory.

• In flakes, the .outPath attribute of a flake now always refers to the directory containing the flake.nix. This was not the case for when flake.nix was in a subdirectory of e.g. a git repository. The root of the source of a flake in a subdirectory is still available in .sourceInfo.outPath.

• The builtins.readDir function has been optimized when encountering not-yet-known file types from POSIX's readdir. In such cases the type of each file is/was discovered by making multiple syscalls. This change makes these operations lazy such that these lookups will only be performed if the attribute is used. This optimization affects a minority of filesystems and operating systems.

• In derivations that use structured attributes, you can now use unsafeDiscardReferences to disable scanning a given output for runtime dependencies:

  __structuredAttrs = true;
  unsafeDiscardReferences.out = true;
  

  This is useful e.g. when generating self-contained filesystem images with their own embedded Nix store: hashes found inside such an image refer to the embedded store and not to the host's Nix store.

  This requires the discard-references experimental feature.