Known blockers

• Feature gate readonly perms on promoted files #12746
  • Make promoted files read-only #12519 needs to be reverted or feature gated behind a dune version
  • We reverted this in Revert "Make promoted files read-only" #12808
• [OxCaml] Parameterized libraries: library instantiation #12088
  • We would like to complete at least the last substantive bit of work from Support for Parameterized Libraries:
• Copyfile stubs fail on alpine linux #12896
  • fix(copyfile): inline linux/version.h #12901
• breakage with dune format-dune-file and opam-dune-lint #12897
  • This will need an upper bound placed on dune for the opam repo package, then followup fixes for integration with the the package.
• Comment being stripped unnecessarily in cram test #12899
  • fix(cram): lexing of single space comment after output #12903
• dune hangs in mdx tests waiting for _build/default/_build/.rpc/dune #12900
  • This is reported as being present already in dune 3.20.2. We want to fix it ASAP, of course, but it is not a regression introduced in the current trunk, so it will get triaged as a normal bug.
  • (It is also a unusual edge condition).
• Nesting of INSIDE_DUNE and build concurrency #12737
  • OxCaml will need to update their opam file to use a released dune, so it would be good to get this fix for the concurrency issue with package management in.
  • We agreed in the dune-dev meeting today that we would not block on this, but target the fix for the next release.

Preparation

• Run mirage tests: https://github.com/ocaml/dune/actions/runs/19950862217
• [new release] dune (17 packages) (3.21.0~alpha2) opam-repository#29042
  • regressions detected
• [ ][new release] dune (17 packages) (3.21.0~alpha3) opam-repository#29070

Release

• Update dune changelog to 3.21.0 on 3.21 branch [link to dune PR]
• Open then pull request on opam-repository [link to OPAM PR]
  • [new release] dune (17 packages) (3.21.0~alpha2) opam-repository#29042
• Triage (ensure it does not break anything)
• Update nix-overlays with the new version [link to nix-overlays PRs]

Post-release

• Merge dune changelog in main [link to dune PR]
• Update ocaml.org changelog [link to ocaml.org PR]
• Write a post about the release on Discuss [link to post]
• Store the revdeps error file in the logs
• Create a next release milestone
• Increase lang dune number

Last stage

• Close tracking issue