Dune 3.12.1

We're pleased to announce the release of Dune 3.12!

Note that due to a mistake during the release process, version 3.12.0 was not published to opam and should not be used.

This version contains many fixes but we would like to highlight the following features:

  • dune ocaml doc is a new command that will build the docs of your package, and open them in a web browser directly.
  • a new set of odoc rules will build documentation for the whole switch. It can be invoked by dune build @doc-new. Note that this is still experimental.
  • Dune can now be built and installed on Haiku.
See full changelog


  • Introduce $ dune ocaml doc to open and browse documentation. (#7262, fixes #6831, @EmileTrotignon)

  • dune cache trim now accepts binary byte units: KiB, MiB, etc. (#8618, @Alizter)

  • Introduce the runtest_alias field to the cram stanza. This allows removing default runtest alias from tests. (@rgrinberg, #8887)

  • Display cache location in Dune log (#8974, @nojb)

  • Dune can now be built and installed on Haiku (#8795, fix #8551, @Alizter)

  • Mark installed directories in dune-package files. This fixes (package) dependencies against packages that contain such directories. (#8953, fixes #8915, @emillon)

  • Introduce new experimental odoc rules (#8803, @jonjudlam)


  • dune-build-info: when version="" is found in a META file, we now return None as a version string (#9177, @emillon)

  • No longer force colors for OCaml 4.03 and 4.04 (#8778, @rgrinberg)

  • Dependencies in the copying sandbox are now writeable (#8920, @rgrinberg)

  • Rules that only use internal dune actions (write-file, echo, etc.) can now be sandboxed. (#9041, fixes #8854, @rgrinberg)

  • Add test_ prefix to default test name in dune init project (#9257, fixes #9131, @9sako6)


  • Do not ignore libraries named bigarray when they are defined in conjunction with OCaml 5.0 (#8902, fixes #8901, @rgrinberg)

  • Correctly ignore bigarray on recent versions of OCaml (#9076, @rgrinberg)

  • Absent packages shouldn't prevent all rules from being loaded (#8948, fixes #8630, @rgrinberg)

  • Correctly determine the stanza of menhir modules when (include_subdirs qualified) is enabled (@rgrinberg, #8949, fixes #7610)

  • Re-run actions whenever (expand_aliases_in_sandbox) changes (#8990, @rgrinberg)

  • Do not re-run rules when their location changes (#9052, @rgrinberg)

  • [coq rules] Be more tolerant when coqc --print-version / --config don't work properly, and fallback to a reasonable default. This fixes problems when building Coq projects with (stdlib no) and likely other cases. (#8966, fix #8958, @Alizter, reported by Lasse Blaauwbroek)

  • Dune will now run at a lower framerate of 15 fps rather than 60 when INSIDE_EMACS. (#8812, @Alizter)