CHANGES:

• enabled_if now supports arch_sixtyfour variable (#8023, fixes #7997, @Alizter)

• Use posix_spawn instead of fork on MacOS. This gives us a performance boost and allows us to re-enable thread. (#8090, @rgrinberg)

• Experimental: Added a $ dune monitor command that can connect to a running dune build in watch mode and display the errors and progress. (#8152, @Alizter)

• The progress RPC procedure now has an extra field for the In_progress constructor for the number of failed jobs. (#8212, @Alizter)

• Add a --preview flag to dune fmt which causes it to print out the changes it would make without applying them (#8289, @gridbugs)

• Introduce (source_trees ..) to the install stanza to allow installing entire source trees. (#8349, @rgrinberg)

• Add --stop-on-first-error option to dune build which will terminate the build when the first error is encountered. (#8400, @pmwhite and @Alizter)

• Dune now displays the number of errors when waiting for changes in watch mode. (#8408, fixes #6889, @Alizter)

• Add with_prefix keyword for changing the prefix of the destination of installed files matched by globs. (#8416, @gridbugs)

• Added experimental --display tui option for Dune that opens an interactive Terminal User Interface (TUI) when Dune is running. Press '?' to open up a help screen when running for more information. (#8429, @Alizter and @rgrinberg)

• Add a warnings field to dune-project files as a unified mechanism to enable or disable dune warnings (@rgrinberg, 8448)

• dune exec: support syntax like %{bin:program}. This can appear anywhere in the command line, so things like dune exec time %{bin:program} now work. (#6035, #8474, fixes #2691, @emillon, @Leonidas-from-XIV)

• Make copy sandbox support directory targets. (#8705, fixes #7724, @emillon)

• Add a new alias @doc-json to build odoc documentation in JSON format. This output can be consumed by external tools. (#8178, @emillon)

• Modules that were declared in (modules_without_implementation), (private_modules) or (virtual_modules) but not declared in (modules) will raise an error. (#7674, @Alizter)

• No longer emit linkopts(javascript) in META files (#8168, @hhugo)

• Deprecate install destination paths beginning with ".." to prevent packages escaping their designated installation directories. (#8350, @gridbugs)

• RPC message styles are now serialised meaning that RPC diagnostics keep their Ansi styling. (#8516, fixes #6921, @Alizter)

• Truncate output from actions that produce too much output (@tov, #8351)

• Allow libraries to shadow OCaml builtin libraries. Previously, builtin libraries would always take precedence. (@rgrinberg, #8558)

• Remove warning against .dune files generated by pre dune 2.0 (#8611, @rgrinberg)

• dune utop no longer links utop in "custom" mode, which should make this command considerably faster. (#8631, fixes #6894, @nojb)

• Ensure that package names in dune-project are valid opam package names. (#8331, @emillon)

• init: check that module names are valid (#8644, fixes #8252, @emillon)

• dune init: parse --public as a public name (#8603, fixes #7108, @emillon)

• Stop signing source files with substitutions. Sign only binaries instead (#8361, fixes #8360, @anmonteiro)

• Remove versions 0.1 and 0.2 of the experimental ctypes extension. (#8293, @emillon)