In contrast to the upstream OCaml compiler, the OxCaml compiler supports
producing so-called shape files (with extension `.cms`) that contain a
trimmed down version of the type information contained in `.cmt` files.
Building on #13395, this PR adds support to dune for invoking the
compiler with the necessary flag to produce these files
(`-bin-annot-cms`) and makes dune aware that compilation with an OxCaml
compiler can depend on these `.cms` files. (The dependency on `.cms`
files occurs when compiling with OxCaml's extra debug information, which
requires resolving information about the types declared in other
modules.)

Both extensions are guarded behind the language extension `(using oxcaml
0.1)` and should only take effect when compiling with an OxCaml
compiler. Moreover, since this PR already introduces the ability of
compilation to depend on `.cms` files, it is approximately free to add
the ability to depend on `.cmt` files (which also contain the relevant
type information for producing debug information). As such, this PR also
adds support for depending on .cmt files during compilation.

**Help for reviewing.** The PR is split into two commits (and can be
reviewed commit by commit if desired):
1. Support for `-bin-annot-cms` via an env stanza and flags.
2. Support for making `.cms`/`.cmt` files a dependency via the stanza
`cms-cmt-dependency (none | cms | cmt)`.

---------

Signed-off-by: Simon Spies <sspies@janestreet.com>

CHANGES:

### Fixed

- `Dyn.to_string` now uses a smarter way to convert floats. This ensures that
  floats are printed with enough precision to round-trip and are valid OCaml
  lexemes. (ocaml/dune#12982, fixes ocaml/dune#12980, @Alizter)

- Fix `dune install --prefix` failing with relative paths outside the workspace
  like `../foo` (ocaml/dune#12993, fixes ocaml/dune#12241, @benodiwal)

- Delete sandboxes with broken permissions (ocaml/dune#13511, @rgrinberg)

- Fix compiling Menhir parsers that refer to sibling modules within a
  subdirectory of `(include_subdirs qualified)`. (ocaml/dune#13118, fixes ocaml/dune#11119,
  @anmonteiro)

- Fixed the dependency specification of C stubs, which could result in C
  stubs not getting rebuilt when needed (which could in turn lead to
  segmentation faults and other hard-to-track bugs).
  (ocaml/dune#13652, fixes ocaml/dune#13651, @nojb)

- Fix rpc not transferring promotion warnings to the client
  (ocaml/dune#12604, fixes ocaml/dune#12578, @ElectreAAS)

- Fix issue where `dune exec -w` was unable to kill running programs on
  rebuild. (ocaml/dune#12360, fixes ocaml/dune#12323, @Alizter)

- Resolve context and workspace binaries introduced by the respective `(env
  (binaries ..))` stanzas. (ocaml/dune#12952, fixes ocaml/dune#6220, @anmonteiro)

- Fix `diff` promotions originating from sandboxed rules. Previously, they
  would be completely ignored as the sandbox with the promoted file would be
  destroyed if the promotion fired (ocaml/dune#13520, @rgrinberg)

- Fix failure to digest installed directory targets, allowing them to be used
  as dependencies to other rules. (ocaml/dune#13045, @anmonteiro)

- Fix handling of `(select ..)` field when used with `(include_subdirs ..)`.
  `(select <path> from ..)` modules now parse `path` as a relative path
  starting from the module group root (ocaml/dune#13175, fixes ocaml/dune#4383, ocaml/dune#12450,
  @anmonteiro)

- Fix dune trying to kill processes that were already reaped due to race
  conditions (ocaml/dune#13245, @rgrinberg)

- Add `O_CLOEXEC` to all files used for stdin/stdout/stderr (ocaml/dune#13385, @rgrinberg)

- Fix `$ dune promote dir/foo` when `dir` does not exist (ocaml/dune#13493, @rgrinberg)

- Fix `(select ..)` field evaluation when a transitive library has optional
  dependencies (fixes ocaml/dune#13299, ocaml/dune#13389, @anmonteiro)

- Fix sandboxed builds of `library` stanzas that set
  `(stdlib (modules_before_stdlib ..))` (ocaml/dune#13624, @anmonteiro)

- Fixed non-build caches not following `$DUNE_CACHE_ROOT` and instead only
  relying on `$XDG_CACHE_HOME`.
  This means the normal build cache moves:
  `$DUNE_CACHE_ROOT -> $DUNE_CACHE_ROOT/db` (no changes if that variable was
  unset). Affected users can prevent a full cache invalidation by moving
  previous contents:
  `cd $DUNE_CACHE_ROOT; mkdir db; mv <contents of directory> db`.
  (ocaml/dune#11612, fixes ocaml/dune#11584, @ElectreAAS)

- `$ dune promotion list` writes output to stdout rather than stderr (ocaml/dune#13462)

- Improve handling of empty files in the `diff` action. These are now correctly
  distinguished from *empty* files. (ocaml/dune#13696, @rgrinberg)

- Pass `/dev/null` to `--diff-command` instead of non-existent files (ocaml/dune#13696,
  @rgrinberg)

- Fix failure when multiple `rocq.extraction` stanzas existing in a directory
  (ocaml/dune#13531, fixes ocaml/dune#8042, @rlepigre-skylabs-ai)

- Print `$ dune promotion show` output to stdout rather than stderr (ocaml/dune#13481,
  @rgrinberg)

- Fix deadlock in the `memo` library in the presence of dependency cycles
  (ocaml/dune#13625, @anmonteiro)

- Fix promotions that modify a directory into a file (ocaml/dune#13516, fixes ocaml/dune#4067,
  @rgrinberg)

- Fix installation of implementations of virtual libraries. This failed when
  the implementation had no private modules, but the virtual library did
  (ocaml/dune#10635, @rgrinberg)

- Respect the `(dir ..)` field on packages when setting up cram tests (ocaml/dune#13581,
  @rgrinberg)

### Added

- Add support for generating `.cms` files using oxcaml and adding `.cms` or
  `.cmt` files as compilation dependencies (ocaml/dune#13397, @spiessimon)

- Add trace events for custom actions (ocaml/dune#13265, @rgrinberg)

- Allow enabling extensions with `(using ..)` in `dune-workspace` files
  (ocaml/dune#13395, @spiessimon)

- Add sandbox extraction trace event (ocaml/dune#13544, @rgrinberg)

- Add the initial cwd to the first config event (ocaml/dune#13026, @rgrinberg)

- Dune produces trace events in `DUNE_ACTION_TRACE_DIR` if this variable
  is set. (ocaml/dune#13302, @rgrinberg)

- Add file watching events to the trace file (ocaml/dune#13038, @rgrinberg)

- Introduce the `$ dune trace cat` subcommand to view the trace file. (ocaml/dune#13055,
  @rgrinberg)

- Add diagnostic events to the trace. (ocaml/dune#13041, @rgrinberg)

- Add `DUNE_JOBS` environment variable for controlling concurrency of Dune from
  environment. The `INSIDE_DUNE` variable also now no longer controls
  concurrency (ocaml/dune#12800, @Alizter)

- Support for Rocq expected output tests (ocaml/dune#13632, @rlepigre-skylabs-ai)

- Add `rusage` information to completed processes in the trace (@rgrinberg,
  ocaml/dune#13241)

- Add process start events to the trace (ocaml/dune#13261, rgrinberg)

- Generate odoc documentation in markdown using the `@doc-markdown` alias
  (ocaml/dune#12581, @davesnx)

- Add timing information for every command executed by cram (ocaml/dune#13092,
  @rgrinberg)

- Add the workspace root to the config trace event (ocaml/dune#12922, @rgrinberg)

- Introduce the `dune-action-trace` library. This public library is to be used
  by custom actions to emit trace events while executed as part of a dune
  build. The trace events emitted through this library will be incorporated
  into dune's own trace (ocaml/dune#13348, @rgrinberg)

- Add `dune-find-dominating` to `dune.el`, a command to find the
  dominating dune file. (ocaml/dune#12696, @arvidj)

- Add a `--no-recursive` flag to `$ dune describe workspace` (ocaml/dune#13590, @rgrinberg)

- Trace events for files written directly by dune (ocaml/dune#13618, @rgrinberg)

- Allow expansion of special forms like `(:include ..)` and `%{read-lines:..}`
  in the `modules` specification for the `ocamllex`, `ocamlyacc` and `menhir`
  stanzas. (ocaml/dune#13105, ocaml/dune#13135, ocaml/dune#13157, @anmonteiro)

- Add a trace event for snapshotting the sandbox (ocaml/dune#13541, @rgrinberg)

- Add signal send and receive events to the trace (ocaml/dune#13193, @rgrinberg)

- Emit final trace event before exiting. (ocaml/dune#13018, @rgrinberg)

- `dune runtest` can now run individual test executables from `(tests)` stanzas
  and inline tests from `(library (inline_tests))` stanzas by providing their
  source files as arguments. (ocaml/dune#13064, fixes ocaml/dune#870, @Alizter)

- Add a `shell` field to the cram stanza. This field allows customizing the
  shell to be `bash` rather than `sh` (ocaml/dune#13083, @haochenx)

### Changed

- Start sandboxing the execution of tests defined with the `test` and `tests`
  stanzas (ocaml/dune#13510, ocaml/dune#13617, @rgrinberg)

- Disabled cram tests can now be run explicitly with `dune runtest disabled.t`.
  The `enabled_if` field now only controls whether a test is included in
  the `@runtest` alias. (ocaml/dune#13081, @Alizter)

- Process categories in trace events are moved to their own field in `args`
  (ocaml/dune#13024, @rgrinberg)

- Sandbox running `ocamllex` and `ocamlyacc` actions. (ocaml/dune#13098, @anmonteiro)

- Sandboxing mdx test actions is now the default starting from `0.5` (ocaml/dune#13504,
  @rgrinberg)

- Start sandboxing Melange rules by default in the `(library ..)` and
  `(melange.emit ..)` stanzas (ocaml/dune#13619, @anmonteiro)

- Introduce a promotion trace event and remove the corresponding verbose log
  message. (ocaml/dune#12949, ocaml/dune#13444, @rgrinberg)

- Change dune's trace format to emit canonical s-expressions. This improves
  performance and is better aligned with dune's usage of the format
  elsewhere. `$ dune trace cat` can also emit the trace in `--chrome-trace`
  for perfetto, or `--sexp` for regular s-expressions for interactive usage.
  (ocaml/dune#13059, @rgrinberg)

- Move all logging statements to the trace file. All log statements now contain
  structured payloads (ocaml/dune#13015, fixes ocaml/dune#12904, @rgrinberg)

- Add a target resolution event to replace the equivalent log message (ocaml/dune#12955,
  @rgrinberg)

CHANGES:

### Fixed

- `Dyn.to_string` now uses a smarter way to convert floats. This ensures that
  floats are printed with enough precision to round-trip and are valid OCaml
  lexemes. (ocaml/dune#12982, fixes ocaml/dune#12980, @Alizter)

- Fix `dune install --prefix` failing with relative paths outside the workspace
  like `../foo` (ocaml/dune#12993, fixes ocaml/dune#12241, @benodiwal)

- Place the default trace file inside the build directory at the
  workspace root, rather than relative to the current directory.
  (ocaml/dune#13735, @vouillon)

- Fixed interpreting relative paths in `%{bin:..}` and `%{bin-available:..}`.
  These are now interpreted correctly, relative to the dune file they're in.
  (ocaml/dune#13712, fixes ocaml/dune#9564, @anmonteiro)

- Delete sandboxes with broken permissions (ocaml/dune#13511, @rgrinberg)

- Fix compiling Menhir parsers that refer to sibling modules within a
  subdirectory of `(include_subdirs qualified)`. (ocaml/dune#13118, fixes ocaml/dune#11119,
  @anmonteiro)

- Fixed the dependency specification of C stubs, which could result in C
  stubs not getting rebuilt when needed (which could in turn lead to
  segmentation faults and other hard-to-track bugs).
  (ocaml/dune#13652, fixes ocaml/dune#13651, @nojb)

- Fix the Dune cache on Windows by correctly handling renames onto read-only
  files. Before this change, the Dune cache would be filled but the stored
  artifacts would not generally be usable by Dune. (ocaml/dune#13713, @Nevor)

- Fix rpc not transferring promotion warnings to the client
  (ocaml/dune#12604, fixes ocaml/dune#12578, @ElectreAAS)

- Fix issue where `dune exec -w` was unable to kill running programs on
  rebuild. (ocaml/dune#12360, fixes ocaml/dune#12323, @Alizter)

- Fix package extraction on systems with tar implementations that don't
  auto-detect compression (e.g., OpenBSD). Dune now passes explicit
  decompression flags (-z for gzip, -j for bzip2) when needed, and provides
  clear error messages for unsupported formats like XZ and LZMA. (ocaml/dune#13688,
  fixes ocaml/dune#10123, @Alizter)

- Resolve context and workspace binaries introduced by the respective `(env
  (binaries ..))` stanzas. (ocaml/dune#12952, fixes ocaml/dune#6220, @anmonteiro)

- Fix `diff` promotions originating from sandboxed rules. Previously, they
  would be completely ignored as the sandbox with the promoted file would be
  destroyed if the promotion fired (ocaml/dune#13520, @rgrinberg)

- Fix failure to digest installed directory targets, allowing them to be used
  as dependencies to other rules. (ocaml/dune#13045, @anmonteiro)

- Fix handling of `(select ..)` field when used with `(include_subdirs ..)`.
  `(select <path> from ..)` modules now parse `path` as a relative path
  starting from the module group root (ocaml/dune#13175, fixes ocaml/dune#4383, ocaml/dune#12450,
  @anmonteiro)

- Fix dune trying to kill processes that were already reaped due to race
  conditions (ocaml/dune#13245, @rgrinberg)

- Add `O_CLOEXEC` to all files used for stdin/stdout/stderr (ocaml/dune#13385, @rgrinberg)

- Fix `$ dune promote dir/foo` when `dir` does not exist (ocaml/dune#13493, @rgrinberg)

- Fix `(select ..)` field evaluation when a transitive library has optional
  dependencies (fixes ocaml/dune#13299, ocaml/dune#13389, @anmonteiro)

- Fix sandboxed builds of `library` stanzas that set
  `(stdlib (modules_before_stdlib ..))` (ocaml/dune#13624, @anmonteiro)

- Dune cache: use of hard links under Windows. (ocaml/dune#13714, @Nevor)

- Fixed non-build caches not following `$DUNE_CACHE_ROOT` and instead only
  relying on `$XDG_CACHE_HOME`.
  This means the normal build cache moves:
  `$DUNE_CACHE_ROOT -> $DUNE_CACHE_ROOT/db` (no changes if that variable was
  unset). Affected users can prevent a full cache invalidation by moving
  previous contents:
  `cd $DUNE_CACHE_ROOT; mkdir db; mv <contents of directory> db`.
  (ocaml/dune#11612, fixes ocaml/dune#11584, @ElectreAAS)

- `$ dune promotion list` writes output to stdout rather than stderr (ocaml/dune#13462)

- Improve handling of empty files in the `diff` action. These are now correctly
  distinguished from *empty* files. (ocaml/dune#13696, @rgrinberg)
- Pass `/dev/null` to `--diff-command` instead of non-existent files (ocaml/dune#13696,
  @rgrinberg)

- Fix failure when multiple `rocq.extraction` stanzas existing in a directory
  (ocaml/dune#13531, fixes ocaml/dune#8042, @rlepigre-skylabs-ai)

- Print `$ dune promotion show` output to stdout rather than stderr (ocaml/dune#13481,
  @rgrinberg)

- Fix deadlock in the `memo` library in the presence of dependency cycles
  (ocaml/dune#13625, @anmonteiro)

- Fix promotions that modify a directory into a file (ocaml/dune#13516, fixes ocaml/dune#4067,
  @rgrinberg)

- Fix installation of implementations of virtual libraries. This failed when
  the implementation had no private modules, but the virtual library did
  (ocaml/dune#10635, @rgrinberg)

- Respect the `(dir ..)` field on packages when setting up cram tests (ocaml/dune#13581,
  @rgrinberg)

### Added

- Add support for generating `.cms` files using oxcaml and adding `.cms` or
  `.cmt` files as compilation dependencies (ocaml/dune#13397, @spiessimon)

- Add trace events for custom actions (ocaml/dune#13265, @rgrinberg)

- Allow enabling extensions with `(using ..)` in `dune-workspace` files
  (ocaml/dune#13395, @spiessimon)

- Add sandbox extraction trace event (ocaml/dune#13544, @rgrinberg)

- Add the initial cwd to the first config event (ocaml/dune#13026, @rgrinberg)

- Dune dune produces trace events in `DUNE_ACTION_TRACE_DIR` if this variable
  is set. (ocaml/dune#13302, @rgrinberg)

- Add file watching events to the trace file (ocaml/dune#13038, @rgrinberg)

- Introduce the `$ dune trace cat` subcommand to view the trace file. (ocaml/dune#13055,
  @rgrinberg)

- Add diagnostic events to the trace. (ocaml/dune#13041, @rgrinberg)

- Add `DUNE_JOBS` environment variable for controlling concurrency of Dune from
  environment. The `INSIDE_DUNE` variable also now no longer controls
  concurrency (ocaml/dune#12800, @Alizter)

- Support for Rocq expected output tests (ocaml/dune#13632, @rlepigre-skylabs-ai)

- Add `rusage` information to completed processes in the trace (@rgrinberg,
  ocaml/dune#13241)

- Add process start events to the trace (ocaml/dune#13261, rgrinberg)

- Generate odoc documentation in markdown using the `@doc-markdown` alias
  (ocaml/dune#12581, @davesnx)

- Add timing information for every command executed by cram (ocaml/dune#13092,
  @rgrinberg)

- Add the workspace root to the config trace event (ocaml/dune#12922, @rgrinberg)

- Introduce the `dune-action-trace` library. This public library is to be used
  by custom actions to emit trace events while executed as part of a dune
  build. The trace events emitted through this library will be incorporated
  into dune's own trace (ocaml/dune#13348, @rgrinberg)

- Add `dune-find-dominating` to `dune.el`, a command to find the
  dominating dune file. (ocaml/dune#12696, @arvidj)

- Add a `--no-recursive` flag to `$ dune describe workspace` (ocaml/dune#13590, @rgrinberg)

- Trace events for files written directly by dune (ocaml/dune#13618, @rgrinberg)

- Allow expansion of special forms like `(:include ..)` and `%{read-lines:..}`
  in the `modules` specification for the `ocamllex`, `ocamlyacc` and `menhir`
  stanzas. (ocaml/dune#13105, ocaml/dune#13135, ocaml/dune#13157, @anmonteiro)

- Add a trace event for snapshotting the asndbox (ocaml/dune#13541, @rgrinberg)

- Add signal send and receive events to the trace (ocaml/dune#13193, @rgrinberg)

- Emit final trace event before exiting. (ocaml/dune#13018, @rgrinberg)

- `dune runtest` can now run individual test executables from `(tests)` stanzas
  and inline tests from `(library (inline_tests))` stanzas by providing their
  source files as arguments. (ocaml/dune#13064, fixes ocaml/dune#870, @Alizter)

- Add a `shell` field to the cram stanza. This field allows customizing the
  shell to be `bash` rather than `sh` (ocaml/dune#13083, @haochenx)

### Changed

- Start sandboxing the execution of tests defined with the `test` and `tests`
  stanzas (ocaml/dune#13510, ocaml/dune#13617, @rgrinberg)

- Disabled cram tests can now be run explicitly with `dune runtest disabled.t`.
  The `enabled_if` field now only controls whether a test is included in
  the `@runtest` alias. (ocaml/dune#13081, @Alizter)

- Process categories in trace events are moved to their own field in `args`
  (ocaml/dune#13024, @rgrinberg)

- Sandbox running `ocamllex` and `ocamlyacc` actions. (ocaml/dune#13098, @anmonteiro)

- Sandboxing mdx test actions is now the default starting from `0.5` (ocaml/dune#13504,
  @rgrinberg)

- Start sandboxing Melange rules by default in the `(library ..)` and
  `(melange.emit ..)` stanzas (ocaml/dune#13619, @anmonteiro)

- Introduce a promotion trace event and remove the corresponding verbose log
  message. (ocaml/dune#12949, ocaml/dune#13444, @rgrinberg)

- Change dune's trace format to emit canonical s-expressions. This improves
  performance and is better aligned with dune's usage of the format
  elsewhere. `$ dune trace cat` can also emit the trace in `--chrome-trace`
  for perfetto, or `--sexp` for regular s-expressions for interactive usage.
  (ocaml/dune#13059, @rgrinberg)

- Move all logging statements to the trace file. All log statements now contain
  structured payloads (ocaml/dune#13015, fixes ocaml/dune#12904, @rgrinberg)

- Add a target resolution event to replace the equivalent log message (ocaml/dune#12955,
  @rgrinberg)

CHANGES:

### Fixed

- `Dyn.to_string` now uses a smarter way to convert floats. This ensures that
  floats are printed with enough precision to round-trip and are valid OCaml
  lexemes. (ocaml/dune#12982, fixes ocaml/dune#12980, @Alizter)

- Fix `dune install --prefix` failing with relative paths outside the workspace
  like `../foo` (ocaml/dune#12993, fixes ocaml/dune#12241, @benodiwal)

- Place the default trace file inside the build directory at the
  workspace root, rather than relative to the current directory.
  (ocaml/dune#13735, @vouillon)

- Fixed interpreting relative paths in `%{bin:..}` and `%{bin-available:..}`.
  These are now interpreted correctly, relative to the dune file they're in.
  (ocaml/dune#13712, fixes ocaml/dune#9564, @anmonteiro)

- Delete sandboxes with broken permissions (ocaml/dune#13511, @rgrinberg)

- Fix compiling Menhir parsers that refer to sibling modules within a
  subdirectory of `(include_subdirs qualified)`. (ocaml/dune#13118, fixes ocaml/dune#11119,
  @anmonteiro)

- Fixed the dependency specification of C stubs, which could result in C
  stubs not getting rebuilt when needed (which could in turn lead to
  segmentation faults and other hard-to-track bugs).
  (ocaml/dune#13652, fixes ocaml/dune#13651, @nojb)

- Fix the Dune cache on Windows by correctly handling renames onto read-only
  files. Before this change, the Dune cache would be filled but the stored
  artifacts would not generally be usable by Dune. (ocaml/dune#13713, @Nevor)

- Fix rpc not transferring promotion warnings to the client
  (ocaml/dune#12604, fixes ocaml/dune#12578, @ElectreAAS)

- Fix issue where `dune exec -w` was unable to kill running programs on
  rebuild. (ocaml/dune#12360, fixes ocaml/dune#12323, @Alizter)

- Fix package extraction on systems with tar implementations that don't
  auto-detect compression (e.g., OpenBSD). Dune now passes explicit
  decompression flags (-z for gzip, -j for bzip2) when needed, and provides
  clear error messages for unsupported formats like XZ and LZMA. (ocaml/dune#13688,
  fixes ocaml/dune#10123, @Alizter)

- Resolve context and workspace binaries introduced by the respective `(env
  (binaries ..))` stanzas. (ocaml/dune#12952, fixes ocaml/dune#6220, @anmonteiro)

- Fix `diff` promotions originating from sandboxed rules. Previously, they
  would be completely ignored as the sandbox with the promoted file would be
  destroyed if the promotion fired (ocaml/dune#13520, @rgrinberg)

- Fix failure to digest installed directory targets, allowing them to be used
  as dependencies to other rules. (ocaml/dune#13045, @anmonteiro)

- Fix handling of `(select ..)` field when used with `(include_subdirs ..)`.
  `(select <path> from ..)` modules now parse `path` as a relative path
  starting from the module group root (ocaml/dune#13175, fixes ocaml/dune#4383, ocaml/dune#12450,
  @anmonteiro)

- Fix dune trying to kill processes that were already reaped due to race
  conditions (ocaml/dune#13245, @rgrinberg)

- Add `O_CLOEXEC` to all files used for stdin/stdout/stderr (ocaml/dune#13385, @rgrinberg)

- Fix `$ dune promote dir/foo` when `dir` does not exist (ocaml/dune#13493, @rgrinberg)

- Fix `(select ..)` field evaluation when a transitive library has optional
  dependencies (fixes ocaml/dune#13299, ocaml/dune#13389, @anmonteiro)

- Fix sandboxed builds of `library` stanzas that set
  `(stdlib (modules_before_stdlib ..))` (ocaml/dune#13624, @anmonteiro)

- Dune cache: use of hard links under Windows. (ocaml/dune#13714, @Nevor)

- Fixed non-build caches not following `$DUNE_CACHE_ROOT` and instead only
  relying on `$XDG_CACHE_HOME`.
  This means the normal build cache moves:
  `$DUNE_CACHE_ROOT -> $DUNE_CACHE_ROOT/db` (no changes if that variable was
  unset). Affected users can prevent a full cache invalidation by moving
  previous contents:
  `cd $DUNE_CACHE_ROOT; mkdir db; mv <contents of directory> db`.
  (ocaml/dune#11612, fixes ocaml/dune#11584, @ElectreAAS)

- `$ dune promotion list` writes output to stdout rather than stderr (ocaml/dune#13462)

- Improve handling of empty files in the `diff` action. These are now correctly
  distinguished from *empty* files. (ocaml/dune#13696, @rgrinberg)
- Pass `/dev/null` to `--diff-command` instead of non-existent files (ocaml/dune#13696,
  @rgrinberg)

- Fix failure when multiple `rocq.extraction` stanzas existing in a directory
  (ocaml/dune#13531, fixes ocaml/dune#8042, @rlepigre-skylabs-ai)

- Print `$ dune promotion show` output to stdout rather than stderr (ocaml/dune#13481,
  @rgrinberg)

- Fix deadlock in the `memo` library in the presence of dependency cycles
  (ocaml/dune#13625, @anmonteiro)

- Fix promotions that modify a directory into a file (ocaml/dune#13516, fixes ocaml/dune#4067,
  @rgrinberg)

- Fix installation of implementations of virtual libraries. This failed when
  the implementation had no private modules, but the virtual library did
  (ocaml/dune#10635, @rgrinberg)

- Respect the `(dir ..)` field on packages when setting up cram tests (ocaml/dune#13581,
  @rgrinberg)

### Added

- Add support for generating `.cms` files using oxcaml and adding `.cms` or
  `.cmt` files as compilation dependencies (ocaml/dune#13397, @spiessimon)

- Add trace events for custom actions (ocaml/dune#13265, @rgrinberg)

- Allow enabling extensions with `(using ..)` in `dune-workspace` files
  (ocaml/dune#13395, @spiessimon)

- Add sandbox extraction trace event (ocaml/dune#13544, @rgrinberg)

- Add the initial cwd to the first config event (ocaml/dune#13026, @rgrinberg)

- Dune dune produces trace events in `DUNE_ACTION_TRACE_DIR` if this variable
  is set. (ocaml/dune#13302, @rgrinberg)

- Add file watching events to the trace file (ocaml/dune#13038, @rgrinberg)

- Introduce the `$ dune trace cat` subcommand to view the trace file. (ocaml/dune#13055,
  @rgrinberg)

- Add diagnostic events to the trace. (ocaml/dune#13041, @rgrinberg)

- Add `DUNE_JOBS` environment variable for controlling concurrency of Dune from
  environment. The `INSIDE_DUNE` variable also now no longer controls
  concurrency (ocaml/dune#12800, @Alizter)

- Support for Rocq expected output tests (ocaml/dune#13632, @rlepigre-skylabs-ai)

- Add `rusage` information to completed processes in the trace (@rgrinberg,
  ocaml/dune#13241)

- Add process start events to the trace (ocaml/dune#13261, rgrinberg)

- Generate odoc documentation in markdown using the `@doc-markdown` alias
  (ocaml/dune#12581, @davesnx)

- Add timing information for every command executed by cram (ocaml/dune#13092,
  @rgrinberg)

- Add the workspace root to the config trace event (ocaml/dune#12922, @rgrinberg)

- Introduce the `dune-action-trace` library. This public library is to be used
  by custom actions to emit trace events while executed as part of a dune
  build. The trace events emitted through this library will be incorporated
  into dune's own trace (ocaml/dune#13348, @rgrinberg)

- Add `dune-find-dominating` to `dune.el`, a command to find the
  dominating dune file. (ocaml/dune#12696, @arvidj)

- Add a `--no-recursive` flag to `$ dune describe workspace` (ocaml/dune#13590, @rgrinberg)

- Trace events for files written directly by dune (ocaml/dune#13618, @rgrinberg)

- Allow expansion of special forms like `(:include ..)` and `%{read-lines:..}`
  in the `modules` specification for the `ocamllex`, `ocamlyacc` and `menhir`
  stanzas. (ocaml/dune#13105, ocaml/dune#13135, ocaml/dune#13157, @anmonteiro)

- Add a trace event for snapshotting the asndbox (ocaml/dune#13541, @rgrinberg)

- Add signal send and receive events to the trace (ocaml/dune#13193, @rgrinberg)

- Emit final trace event before exiting. (ocaml/dune#13018, @rgrinberg)

- `dune runtest` can now run individual test executables from `(tests)` stanzas
  and inline tests from `(library (inline_tests))` stanzas by providing their
  source files as arguments. (ocaml/dune#13064, fixes ocaml/dune#870, @Alizter)

- Add a `shell` field to the cram stanza. This field allows customizing the
  shell to be `bash` rather than `sh` (ocaml/dune#13083, @haochenx)

### Changed

- Start sandboxing the execution of tests defined with the `test` and `tests`
  stanzas (ocaml/dune#13510, ocaml/dune#13617, @rgrinberg)

- Disabled cram tests can now be run explicitly with `dune runtest disabled.t`.
  The `enabled_if` field now only controls whether a test is included in
  the `@runtest` alias. (ocaml/dune#13081, @Alizter)

- Process categories in trace events are moved to their own field in `args`
  (ocaml/dune#13024, @rgrinberg)

- Sandbox running `ocamllex` and `ocamlyacc` actions. (ocaml/dune#13098, @anmonteiro)

- Sandboxing mdx test actions is now the default starting from `0.5` (ocaml/dune#13504,
  @rgrinberg)

- Start sandboxing Melange rules by default in the `(library ..)` and
  `(melange.emit ..)` stanzas (ocaml/dune#13619, @anmonteiro)

- Introduce a promotion trace event and remove the corresponding verbose log
  message. (ocaml/dune#12949, ocaml/dune#13444, @rgrinberg)

- Change dune's trace format to emit canonical s-expressions. This improves
  performance and is better aligned with dune's usage of the format
  elsewhere. `$ dune trace cat` can also emit the trace in `--chrome-trace`
  for perfetto, or `--sexp` for regular s-expressions for interactive usage.
  (ocaml/dune#13059, @rgrinberg)

- Move all logging statements to the trace file. All log statements now contain
  structured payloads (ocaml/dune#13015, fixes ocaml/dune#12904, @rgrinberg)

- Add a target resolution event to replace the equivalent log message (ocaml/dune#12955,
  @rgrinberg)

CHANGES:

### Fixed

- `Dyn.to_string` now uses a smarter way to convert floats. This ensures that
  floats are printed with enough precision to round-trip and are valid OCaml
  lexemes. (ocaml/dune#12982, fixes ocaml/dune#12980, @Alizter)

- Fix `dune install --prefix` failing with relative paths outside the workspace
  like `../foo` (ocaml/dune#12993, fixes ocaml/dune#12241, @benodiwal)

- Place the default trace file inside the build directory at the
  workspace root, rather than relative to the current directory.
  (ocaml/dune#13735, @vouillon)

- Fixed interpreting relative paths in `%{bin:..}` and `%{bin-available:..}`.
  These are now interpreted correctly, relative to the dune file they're in.
  (ocaml/dune#13712, fixes ocaml/dune#9564, @anmonteiro)

- Delete sandboxes with broken permissions (ocaml/dune#13511, @rgrinberg)

- Fix compiling Menhir parsers that refer to sibling modules within a
  subdirectory of `(include_subdirs qualified)`. (ocaml/dune#13118, fixes ocaml/dune#11119,
  @anmonteiro)

- Fixed the dependency specification of C stubs, which could result in C
  stubs not getting rebuilt when needed (which could in turn lead to
  segmentation faults and other hard-to-track bugs).
  (ocaml/dune#13652, fixes ocaml/dune#13651, @nojb)

- Fix the Dune cache on Windows by correctly handling renames onto read-only
  files. Before this change, the Dune cache would be filled but the stored
  artifacts would not generally be usable by Dune. (ocaml/dune#13713, @Nevor)

- Fix rpc not transferring promotion warnings to the client
  (ocaml/dune#12604, fixes ocaml/dune#12578, @ElectreAAS)

- Fix issue where `dune exec -w` was unable to kill running programs on
  rebuild. (ocaml/dune#12360, fixes ocaml/dune#12323, @Alizter)

- Resolve context and workspace binaries introduced by the respective `(env
  (binaries ..))` stanzas. (ocaml/dune#12952, fixes ocaml/dune#6220, @anmonteiro)

- Fix `diff` promotions originating from sandboxed rules. Previously, they
  would be completely ignored as the sandbox with the promoted file would be
  destroyed if the promotion fired (ocaml/dune#13520, @rgrinberg)

- Fix failure to digest installed directory targets, allowing them to be used
  as dependencies to other rules. (ocaml/dune#13045, @anmonteiro)

- Fix handling of `(select ..)` field when used with `(include_subdirs ..)`.
  `(select <path> from ..)` modules now parse `path` as a relative path
  starting from the module group root (ocaml/dune#13175, fixes ocaml/dune#4383, ocaml/dune#12450,
  @anmonteiro)

- Fix dune trying to kill processes that were already reaped due to race
  conditions (ocaml/dune#13245, @rgrinberg)

- Add `O_CLOEXEC` to all files used for stdin/stdout/stderr (ocaml/dune#13385, @rgrinberg)

- Fix `$ dune promote dir/foo` when `dir` does not exist (ocaml/dune#13493, @rgrinberg)

- Fix `(select ..)` field evaluation when a transitive library has optional
  dependencies (fixes ocaml/dune#13299, ocaml/dune#13389, @anmonteiro)

- Fix sandboxed builds of `library` stanzas that set
  `(stdlib (modules_before_stdlib ..))` (ocaml/dune#13624, @anmonteiro)

- Dune cache: use of hard links under Windows. (ocaml/dune#13714, @Nevor)

- Fixed non-build caches not following `$DUNE_CACHE_ROOT` and instead only
  relying on `$XDG_CACHE_HOME`.
  This means the normal build cache moves:
  `$DUNE_CACHE_ROOT -> $DUNE_CACHE_ROOT/db` (no changes if that variable was
  unset). Affected users can prevent a full cache invalidation by moving
  previous contents:
  `cd $DUNE_CACHE_ROOT; mkdir db; mv <contents of directory> db`.
  (ocaml/dune#11612, fixes ocaml/dune#11584, @ElectreAAS)

- `$ dune promotion list` writes output to stdout rather than stderr (ocaml/dune#13462)

- Improve handling of empty files in the `diff` action. These are now correctly
  distinguished from *empty* files. (ocaml/dune#13696, @rgrinberg)
- Pass `/dev/null` to `--diff-command` instead of non-existent files (ocaml/dune#13696,
  @rgrinberg)

- Fix failure when multiple `rocq.extraction` stanzas existing in a directory
  (ocaml/dune#13531, fixes ocaml/dune#8042, @rlepigre-skylabs-ai)

- Print `$ dune promotion show` output to stdout rather than stderr (ocaml/dune#13481,
  @rgrinberg)

- Fix deadlock in the `memo` library in the presence of dependency cycles
  (ocaml/dune#13625, @anmonteiro)

- Fix promotions that modify a directory into a file (ocaml/dune#13516, fixes ocaml/dune#4067,
  @rgrinberg)

- Fix installation of implementations of virtual libraries. This failed when
  the implementation had no private modules, but the virtual library did
  (ocaml/dune#10635, @rgrinberg)

- Respect the `(dir ..)` field on packages when setting up cram tests (ocaml/dune#13581,
  @rgrinberg)

### Added

- Add support for generating `.cms` files using oxcaml and adding `.cms` or
  `.cmt` files as compilation dependencies (ocaml/dune#13397, @spiessimon)

- Add trace events for custom actions (ocaml/dune#13265, @rgrinberg)

- Allow enabling extensions with `(using ..)` in `dune-workspace` files
  (ocaml/dune#13395, @spiessimon)

- Add sandbox extraction trace event (ocaml/dune#13544, @rgrinberg)

- Add the initial cwd to the first config event (ocaml/dune#13026, @rgrinberg)

- Dune dune produces trace events in `DUNE_ACTION_TRACE_DIR` if this variable
  is set. (ocaml/dune#13302, @rgrinberg)

- Add file watching events to the trace file (ocaml/dune#13038, @rgrinberg)

- Introduce the `$ dune trace cat` subcommand to view the trace file. (ocaml/dune#13055,
  @rgrinberg)

- Add diagnostic events to the trace. (ocaml/dune#13041, @rgrinberg)

- Add `DUNE_JOBS` environment variable for controlling concurrency of Dune from
  environment. The `INSIDE_DUNE` variable also now no longer controls
  concurrency (ocaml/dune#12800, @Alizter)

- Support for Rocq expected output tests (ocaml/dune#13632, @rlepigre-skylabs-ai)

- Add `rusage` information to completed processes in the trace (@rgrinberg,
  ocaml/dune#13241)

- Add process start events to the trace (ocaml/dune#13261, rgrinberg)

- Generate odoc documentation in markdown using the `@doc-markdown` alias
  (ocaml/dune#12581, @davesnx)

- Add timing information for every command executed by cram (ocaml/dune#13092,
  @rgrinberg)

- Add the workspace root to the config trace event (ocaml/dune#12922, @rgrinberg)

- Introduce the `dune-action-trace` library. This public library is to be used
  by custom actions to emit trace events while executed as part of a dune
  build. The trace events emitted through this library will be incorporated
  into dune's own trace (ocaml/dune#13348, @rgrinberg)

- Add `dune-find-dominating` to `dune.el`, a command to find the
  dominating dune file. (ocaml/dune#12696, @arvidj)

- Add a `--no-recursive` flag to `$ dune describe workspace` (ocaml/dune#13590, @rgrinberg)

- Trace events for files written directly by dune (ocaml/dune#13618, @rgrinberg)

- Allow expansion of special forms like `(:include ..)` and `%{read-lines:..}`
  in the `modules` specification for the `ocamllex`, `ocamlyacc` and `menhir`
  stanzas. (ocaml/dune#13105, ocaml/dune#13135, ocaml/dune#13157, @anmonteiro)

- Add a trace event for snapshotting the asndbox (ocaml/dune#13541, @rgrinberg)

- Add signal send and receive events to the trace (ocaml/dune#13193, @rgrinberg)

- Emit final trace event before exiting. (ocaml/dune#13018, @rgrinberg)

- `dune runtest` can now run individual test executables from `(tests)` stanzas
  and inline tests from `(library (inline_tests))` stanzas by providing their
  source files as arguments. (ocaml/dune#13064, fixes ocaml/dune#870, @Alizter)

- Add a `shell` field to the cram stanza. This field allows customizing the
  shell to be `bash` rather than `sh` (ocaml/dune#13083, @haochenx)

### Changed

- Start sandboxing the execution of tests defined with the `test` and `tests`
  stanzas (ocaml/dune#13510, ocaml/dune#13617, @rgrinberg)

- Disabled cram tests can now be run explicitly with `dune runtest disabled.t`.
  The `enabled_if` field now only controls whether a test is included in
  the `@runtest` alias. (ocaml/dune#13081, @Alizter)

- Process categories in trace events are moved to their own field in `args`
  (ocaml/dune#13024, @rgrinberg)

- Sandbox running `ocamllex` and `ocamlyacc` actions. (ocaml/dune#13098, @anmonteiro)

- Sandboxing mdx test actions is now the default starting from `0.5` (ocaml/dune#13504,
  @rgrinberg)

- Start sandboxing Melange rules by default in the `(library ..)` and
  `(melange.emit ..)` stanzas (ocaml/dune#13619, @anmonteiro)

- Introduce a promotion trace event and remove the corresponding verbose log
  message. (ocaml/dune#12949, ocaml/dune#13444, @rgrinberg)

- Change dune's trace format to emit canonical s-expressions. This improves
  performance and is better aligned with dune's usage of the format
  elsewhere. `$ dune trace cat` can also emit the trace in `--chrome-trace`
  for perfetto, or `--sexp` for regular s-expressions for interactive usage.
  (ocaml/dune#13059, @rgrinberg)

- Move all logging statements to the trace file. All log statements now contain
  structured payloads (ocaml/dune#13015, fixes ocaml/dune#12904, @rgrinberg)

- Add a target resolution event to replace the equivalent log message (ocaml/dune#12955,
  @rgrinberg)