Dune 3.21.0

Fixed

• Fix include_subdirs qualified incorrectly picking the furthest module instead of the closest when resolving module name ambiguities. (#12587, @ElectreAAS and @Alizter)

• Fix: include the module alias in the transitive dependency closure with (include_subdirs qualified). (#12299, @anmonteiro)

• Improve error messages for invalid version formats containing non-ASCII characters. Previously, non-ASCII characters in version strings (e.g., (lang dune è) or (using menhir π3.14)) would fail with a generic "Invalid file" error. Now they display a clear message: "Invalid atom: contains non-ASCII character(s). Atoms must only contain ASCII characters." The fix is implemented at the lexer level, providing consistent error handling across all s-expression parsing. (#12844, fixes #12836, @benodiwal)

• Pass private modules with -H when this is available (#12666, @rgrinberg)

• Allow multiple modules in (modules_flags ...), in coq.theory (#12733, @rlepigre)

• Improve error message for invalid version formats in both (lang dune ...) and (using extension ...) declarations. Changes "Atom of the form NNN.NNN expected" to "Invalid version. Version must be two numbers separated by a dot." (#12833, @benodiwal)

• Fix crash when running dune build @check on a library with virtual modules. (#12644, fixes #12636, @Alizter)

• Provide a more informative error message when (pkg enabled) is put in dune-project instead of dune-workspace. (#12802, fixes #12801, @benodiwal)

• Improve error message when invalid version strings are used in dune-project files. Non-ASCII characters and malformed versions now show a helpful hint with an example of the correct format. (#12794, fixes #12751, @benodiwal)

• Stop hiding the root_module from the include path (#12239, @rgrinberg)

• Allow $ dune init to work on absolute paths (#12601, fixes #7806, @rgrinberg)

• (include_subdirs qualified): Add missing alias dependency to module group. (#12530, @anmonteiro)

• Add Melange compilation to the @all alias in libraries (#12628, @anmonteiro)

• Fix greedy version location in lang declarations. Previously, error locations for invalid lang versions would span multiple bytes for multi-byte UTF-8 characters, causing carets to appear misaligned and seemingly include the closing parenthesis. Now, error locations for ASCII strings show the full length (e.g., "Ali" shows ^^^), while non-ASCII strings show only the first byte (e.g., "è" shows ^) to avoid multi-byte character display issues. (#12869, fixes #12806, @benodiwal)

• melange support: don't emit empty JavaScript modules for generated module aliases. (#12464, @anmonteiro)

Added

• (Experimental): Introduce the library_parameter stanza. It allows users to declare a parameter when using the OxCaml compiler. (#11963, implements #12084, @maiste)
• Added the ability to scroll horizontally in TUI. (#12386, @Alizter)
• Feature: Include shell command that was executed when a cram test has occurred in the error message (#12307, @rgrinberg)
• support expanding variables in (promote (into ..)) (#12832, fixes #12742, @anmonteiro)
• Add support for %{cmt:...} and %{cmti:...} variables to reference compiled annotation files (.cmt and .cmti) containing typed abstract syntax trees with location and type information. (#12634, grants #12633, @Alizter)
• Add $ dune describe tests to describe the tests in the workspace (@Gromototo, #12545, fixes #12030)
• Add argv, the process environment, and the dune version to the config event in the trace (#12909, @rgrinberg)
• Allow dune runtest to properly run while a watch mode server is running. (#12473, grants #8114, @gridbugs and @ElectreAAS)
• Use copy-on-write (COW) when copying files on filesystems that support it (Btrfs, ZFS, XFS, etc), under Linux. (#12074, fixes #12071, @nojb)
• Add support for Tangled ATproto-based code repositories (#12197, @avsm)
• Add support for instantiating OxCaml parameterised libraries. (#12561, @art-w)
• Add a (conflict_markers error|ignore) option to the cram stanza. When (conflict_markers error) is set, the cram test will fail in the presence of conflict markers. Git, diff3 and jujutsu conflict markers are detected. (#12538, #12617, #12655, fixes #12512, @rgrinberg, @Alizter)
• Introduce a %{ppx:lib1+..+libn} stanza to make it possible to refer to ppx executables built by dune. This is useful for writing tests (#12711, @rgrinberg)
• Introduce a (dir ..) field on packages defined in the dune-project. This field allows to associate a directory with a particular package. This makes dune automatically filter out all stanzas in this directory and its descendants with --only-packages. All users are recommended to switch to using this field. (#12614, fixes #3255, @rgrinberg)
• Add support for DUNE_ROOT environment variable, similar to the existing --root CLI parameter. (fixes #12399 @sir4ur0n)
• Introduce an unused-libs alias to detect unused libraries. (#12623, fixes #650, @rgrinberg)
• Add --files flag to dune describe opam-files to print only the names of the opam files line by line. (#9793, @reynir and @Alizter)
• dune exec now accepts absolute paths inside the workspace. (#12094, @Alizter)
• Add coqdoc_header and coqdoc_footer fields to the coq field of the env stanza, and to the coq.theory stanza, allowing to configure a custom header or footer respectively in the HTML output of coqdoc. (#11131, @rlepigre)
• Allow dune fmt to properly run while a watch mode server is running. Note that the --preview flag is not supported in this mode. (#12064, @ElectreAAS)
• Support for generating _CoqProject files for coq.theory stanzas. (#11752, @rlepigre)
• Added (files) stanza, similar to (dirs) to control which files are visible to Dune on a per-directory basis. (#12879, @nojb)
• Add support for %{ocaml-config:ox} (#12236, @jonludlam)
• Introduce dune promotion show command to display the contents of corrected files that are ready for promotion. This allows users to preview changes before running dune promote. The command accepts file arguments to show specific files, or displays all promotable files when called without arguments. (#12669, fixes #3883, @MixiMaxiMouse)
• New (lang rocq) build mode for Rocq 9.0 and later. This new mode is very similar to the existing (lang coq), except that it doesn't need the coq* compatibility wrappers. As of today (lang rocq) doesn't support yet composed builds with Rocq itself, this will be added later. (lang coq) is deprecated, development is frozen, and will be removed at some point in the future. (#12035, @ejgallego, @lysxia, fixes #11572)

Changed

• Don't run ocamldep to compute false dependencies on the root_module (#12227, @rgrinberg)
• dune format-dune-file now uses the syntax version of the Dune project that contains the file being formatted (if any) instead of using the latest version available, which remains the default if there is no Dune project in scope. (#11865, @nojb)
• Persistent DB and process events have been slightly modified. Persistent DB events have more concise names and job events always include full information. (#12867, @rgrinberg)
• Removed the --trace-extended flag. Its functionality is always enabled when tracing is active (#12908, @rgrinberg)
• The test/dune file generated by dune init proj now depends on the project library. (#12791, @shonfeder)
• Starting with version 3.21 of the Dune language, Dune no longer changes the default set of compiler warnings. For users that would like to keep the old behaviour, the variable %{dune-warnings} can be used in an (env) stanza in a top-level Dune file: (env (dev (flags :standard %{dune-warnings}))). (#12766, @nojb)
• Fix: stop generating cmt files for cinaps binaries (#12530, @rgrinberg)