Wasm_of_ocaml support

.github/workflows/workflow.yml

@@ -190,6 +190,94 @@ jobs:
           # We disable the Dune cache when running the tests
           DUNE_CACHE: disabled
 
+  wasm:
+    name: Wasm_of_ocaml
+    runs-on: ubuntu-latest
+    steps:
+      - name: Install Node
+        uses: actions/setup-node@v4
+        with:
+          node-version: latest
+
+      - name: Restore Cached Binaryen
+        id: cache-binaryen
+        uses: actions/cache/restore@v4
+        with:
+          path: binaryen
+          key: ${{ runner.os }}-binaryen-version_119
+
+      - name: Checkout Binaryen
+        if: steps.cache-binaryen.outputs.cache-hit != 'true'
+        uses: actions/checkout@v4
+        with:
+          repository: WebAssembly/binaryen
+          path: binaryen
+          submodules: true
+          ref: version_119
+
+      - name: Install Ninja
+        if: steps.cache-binaryen.outputs.cache-hit != 'true'
+        run: sudo apt-get install ninja-build
+
+      - name: Build Binaryen
+        if: steps.cache-binaryen.outputs.cache-hit != 'true'
+        working-directory: ./binaryen
+        run: |
+          cmake -G Ninja .
+          ninja
+
+      - name: Cache Binaryen
+        if: steps.cache-binaryen.outputs.cache-hit != 'true'
+        uses: actions/cache/save@v4
+        with:
+          path: binaryen
+          key: ${{ runner.os }}-binaryen-version_119
+
+      - name: Set Binaryen's Path
+        run: |
+          echo "$GITHUB_WORKSPACE/binaryen/bin" >> $GITHUB_PATH
+
+      - name: Checkout Code
+        uses: actions/checkout@v4
+        with:
+          path: dune
+
+      - name: Use OCaml 4.14.x
+        uses: ocaml/setup-ocaml@v3
+        with:
+          ocaml-compiler: 4.14.x
+          opam-pin: false
+          opam-depext: false
+          dune-cache: true
+
+      - name: Update Dune
+        working-directory: ./dune
+        run: opam pin add -n dune . --with-version 3.17.0
+
+      - name: Checkout Wasm_of_ocaml
+        uses: actions/checkout@v4
+        with:
+          repository: ocaml-wasm/wasm_of_ocaml
+          ref: wasm-dune
+          path: wasm_of_ocaml
+
+      - name: Install Wasm_of_ocaml
+        working-directory: ./wasm_of_ocaml
+        run: |
+           opam pin add -n . --with-version `< VERSION`
+           opam install wasm_of_ocaml-compiler
+
+      - name: Set Git User
+        run: |
+          git config --global user.name github-actions[bot]
+          git config --global user.email github-actions[bot]@users.noreply.github.com
+      - name: Run Tests
+        working-directory: ./dune
+        run: opam exec -- make test-wasm
+        env:
+          # We disable the Dune cache when running the tests
+          DUNE_CACHE: disabled
+
   monorepo_benchmark_test:
     name: Build monorepo benchmark docker image
     runs-on: ubuntu-latest

Makefile

@@ -89,6 +89,9 @@ test-windows: $(BIN)
 test-js: $(BIN)
 	$(BIN) build @runtest-js
 
+test-wasm: $(BIN)
+	DUNE_WASM_TEST=enable $(BIN) build @runtest-wasm
+
 test-coq: $(BIN)
 	DUNE_COQ_TEST=enable $(BIN) build @runtest-coq
 

bin/printenv.ml

@@ -27,13 +27,25 @@ let dump sctx ~dir =
     |> Action_builder.of_memo
     >>= Dune_rules.Menhir_env.dump
   and+ coq_dump = Dune_rules.Coq.Coq_rules.coq_env ~dir >>| Dune_rules.Coq.Coq_flags.dump
-  and+ jsoo_dump =
+  and+ jsoo_js_dump =
     let module Js_of_ocaml = Dune_rules.Js_of_ocaml in
-    let* jsoo = Action_builder.of_memo (Dune_rules.Jsoo_rules.jsoo_env ~dir) in
-    Js_of_ocaml.Flags.dump jsoo.flags
+    let* jsoo = Action_builder.of_memo (Dune_rules.Jsoo_rules.jsoo_env ~dir ~mode:JS) in
+    Js_of_ocaml.Flags.dump ~mode:JS jsoo.flags
+  and+ jsoo_wasm_dump =
+    let module Js_of_ocaml = Dune_rules.Js_of_ocaml in
+    let* jsoo = Action_builder.of_memo (Dune_rules.Jsoo_rules.jsoo_env ~dir ~mode:Wasm) in
+    Js_of_ocaml.Flags.dump ~mode:Wasm jsoo.flags
   in
   let env =
-    List.concat [ o_dump; c_dump; link_flags_dump; menhir_dump; coq_dump; jsoo_dump ]
+    List.concat
+      [ o_dump
+      ; c_dump
+      ; link_flags_dump
+      ; menhir_dump
+      ; coq_dump
+      ; jsoo_js_dump
+      ; jsoo_wasm_dump
+      ]
   in
   Super_context.context sctx |> Context.name, env
 ;;

doc/changes/11093.md

@@ -0,0 +1 @@
+- Wasm_of_ocaml support (#11093, @vouillon)

doc/howto/index.rst

@@ -15,6 +15,7 @@ These guides will help you use Dune's features in your project.
    ../sites
    ../instrumentation
    ../jsoo
+   ../wasmoo
    ../melange
    ../virtual-libraries
    ../tests

doc/reference/dune/env.rst

@@ -49,7 +49,24 @@ Fields supported in ``<settings>`` are:
   or not where ``<mode>`` is either ``no``, ``file`` (to generate sourcemap in a ``.map`` file next the the generated javascript file) or ``inline`` (to inline the sourcemap at the end of the generated JavaScript file).
 
 - ``(js_of_ocaml (runtest_alias <alias-name>))`` specifies the alias under which
-  :ref:`inline_tests` and tests (:ref:`tests-stanza`) run for the `js` mode.
+  :ref:`inline_tests` and tests (:ref:`tests-stanza`) run for the ``js`` mode.
+
+- ``(js_of_ocaml (enabled_if <blang expression>))`` specifies whether the ``js`` mode is enabled. It is enabled by default.
+
+- ``(wasm_of_ocaml (flags <flags>)(build_runtime <flags>)(link_flags <flags>))``
+  specifies ``wasm_of_ocaml`` flags. See :ref:`wasmoo-field` for more details.
+
+- ``(wasm_of_ocaml (compilation_mode <mode>))`` controls whether to use separate
+  compilation or not where ``<mode>`` is either ``whole_program`` or
+  ``separate``.
+
+- ``(wasm_of_ocaml (sourcemap <mode>))`` controls whether to generate sourcemap
+  or not where ``<mode>`` is either ``no``, ``file`` (to generate sourcemap in a ``.map`` file next the the generated javascript file) or ``inline`` (to inline the sourcemap at the end of the generated JavaScript file).
+
+- ``(wasm_of_ocaml (runtest_alias <alias-name>))`` specifies the alias under which
+  :ref:`inline_tests` and tests (:ref:`tests-stanza`) run for the ``wasm`` mode.
+
+- ``(wasm_of_ocaml (enabled_if <blang expression>))`` specifies whether the ``wasm`` mode is enabled. It is enabled by default.
 
 - ``(binaries <binaries>)``, where ``<binaries>`` is a list of entries of the
   form ``(<filepath> as <name>)``. ``(<filepath> as <name>)`` makes the binary

doc/reference/dune/executable.rst

@@ -14,12 +14,15 @@ executable stanzas is as follows:
 There can be additional modules in the current directory; you only need to
 specify the entry point. Given an ``executable`` stanza with ``(name <name>)``,
 Dune will know how to build ``<name>.exe``. If requested, it will also know how
-to build ``<name>.bc`` and ``<name>.bc.js`` (Dune 2.0 and up also need specific
-configuration (see the ``modes`` optional field below)).
+to build ``<name>.bc``, ``<name>.bc.js`` and ``<name>.bc.wasm.js`` (Dune 2.0
+and up also needs specific configuration (see the ``modes`` optional field
+below)).
 
 ``<name>.exe`` is a native code executable, ``<name>.bc`` is a bytecode
-executable which requires ``ocamlrun`` to run, and ``<name>.bc.js`` is a
-JavaScript generated using ``js_of_ocaml``.
+executable which requires ``ocamlrun`` to run, ``<name>.bc.js`` is a
+JavaScript generated using ``js_of_ocaml``, and ``<name>.bc.wasm.js`` is a
+Wasm loader script generated using ``wasm_of_ocaml`` (the Wasm modules are included in
+directory ``<name>.bc.wasm.assets``).
 
 Please note: in case native compilation is not available, ``<name>.exe`` will be
 a custom bytecode executable, in the sense of ``ocamlc -custom``. This means
@@ -91,6 +94,8 @@ files for executables. See
 
 - ``js_of_ocaml``: See the section about :ref:`jsoo-field`
 
+- ``wasm_of_ocaml``: See the section about :ref:`wasmoo-field`
+
 - ``flags``, ``ocamlc_flags``, and ``ocamlopt_flags``: See
   :doc:`/concepts/ocaml-flags`.
 
@@ -165,6 +170,7 @@ available.
   non-OCaml application.
 - ``js`` for producing JavaScript from bytecode executables, see
   :doc:`/reference/dune-project/explicit_js_mode`.
+- ``wasm`` for producing JavaScript from bytecode executables.
 - ``plugin`` for producing a plugin (``.cmxs`` if native or ``.cma`` if
   bytecode).
 
@@ -186,6 +192,7 @@ Additionally, you can use the following shorthands:
 - ``byte`` for ``(byte exe)``
 - ``native`` for ``(native exe)``
 - ``js`` for ``(byte js)``
+- ``wasm`` for ``(byte wasm)``
 - ``plugin`` for ``(best plugin)``
 
 For instance, the following ``modes`` fields are all equivalent:
@@ -216,6 +223,7 @@ The extensions for the various linking modes are chosen as follows:
 .. (native/best shared_object) %{ext_dll}
 .. c                           .bc.c
 .. js                          .bc.js
+.. wasm                        .bc.wasm.js
 .. (best plugin)               %{ext_plugin}
 .. (byte plugin)               .cma
 .. (native plugin)             .cmxs
@@ -264,14 +272,38 @@ options using ``(js_of_ocaml (<js_of_ocaml-options>))``.
 - ``(sourcemap <config>)`` where ``<config>>`` is one of ``no``, ``file`` or ``inline``.
   This is only available inside ``executable`` stanzas.
 
+- ``(enabled_if <blang expression>)`` to specify whether the ``js`` mode is enabled. It is enabled by default.
+  This is only available inside ``executable`` stanzas.
+
 ``<flags>`` is specified in the :doc:`/reference/ordered-set-language`.
+``<blang expression>`` is specified using the :doc:`/reference/boolean-language`,
 
 The default values for ``flags``, ``compilation_mode`` and ``sourcemap`` depend on the selected build profile. The
 build profile ``dev`` (the default) will enable inline sourcemap, separate compilation and pretty
 JavaScript output.
 
 See :ref:`jsoo` for more information.
 
+.. _wasmoo-field:
+
+wasm_of_ocaml
+~~~~~~~~~~~~~
+
+In ``library`` and ``executable`` stanzas, you can specify ``wasm_of_ocaml``
+options using ``(wasm_of_ocaml (<wasm_of_ocaml-options>))``.
+
+``<wasm_of_ocaml-options>`` are all optional. They are the same as the ``<js_of_ocaml-options>`` above plus:
+
+- ``(wasm_files (<files-list>))`` to specify ``wasm_of_ocaml``
+  Wasm runtime files.
+
+For the ``(sourcemap <config>)`` option, source maps are generated when ``<config>>`` is either ``file`` or ``inline``. They are put within the ``.bc.wasm.assets``  directory in both cases.
+
+The default values for ``flags``, ``compilation_mode`` and ``sourcemap`` depend on the selected build profile. The
+build profile ``dev`` (the default) will enable sourcemaps, separate compilation and pretty Wasm output.
+
+See :ref:`wasmoo` for more information.
+
 executables
 -----------
 

doc/reference/dune/library.rst

@@ -213,6 +213,10 @@ order to declare a multi-directory library, you need to use the
 
    Sets options for JavaScript compilation, see :ref:`jsoo-field`.
 
+.. describe:: (wasm_of_ocaml ...)
+
+   Sets options for JavaScript compilation, see :ref:`wasmoo-field`.
+
 .. describe:: (flags ...)
 
    See :doc:`/concepts/ocaml-flags`.

doc/tests.rst

@@ -258,14 +258,15 @@ field. Available modes are:
 - ``best`` for running tests in native mode with fallback to byte code,
   if native compilation is not available
 - ``js`` for running tests in JavaScript using Node.js
+- ``wasm`` for running tests in Wasm using Node.js
 
 For instance:
 
 .. code:: ocaml
 
    (library
     (name foo)
-    (inline_tests (modes byte best js))
+    (inline_tests (modes byte best js wasm))
     (preprocess (pps ppx_expect)))
 
 

doc/wasmoo.rst

@@ -0,0 +1,104 @@
+.. _wasmoo:
+
+***************************************
+Wasm Compilation With Wasm_of_ocaml
+***************************************
+
+.. TODO(diataxis)
+
+   This is an how-to guide.
+
+Wasm_of_ocaml_ is a compiler from OCaml to WebAssembly (Wasm for
+short). The compiler works by translating OCaml bytecode to Wasm code.
+
+
+Compiling to Wasm
+=================
+
+Dune has full support for building wasm_of_ocaml libraries and executables transparently.
+There's no need to customise or enable anything to compile OCaml
+libraries/executables to Wasm.
+
+To build a Wasm executable, just define an executable as you would normally.
+Consider this example:
+
+.. code:: console
+
+   $ echo 'print_endline "hello from wasm"' > foo.ml
+
+With the following ``dune`` file:
+
+.. code:: dune
+
+   (executable (name foo) (modes wasm))
+
+And then request the ``.wasm.js`` target:
+
+.. code:: console
+
+    $ dune build ./foo.bc.wasm.js
+    $ node _build/default/foo.bc.wasm.js
+    hello from wasm
+
+If you're using the js_of_ocaml syntax extension, you must remember to add the
+appropriate PPX in the ``preprocess`` field:
+
+.. code:: dune
+
+   (executable
+    (name foo)
+    (modes wasm)
+    (preprocess (pps js_of_ocaml-ppx)))
+
+Selective Compilation
+=====================
+
+The ``js`` and ``wasm`` modes can be selectively disabled using the ``(js_of_ocaml (enabled_if ...))`` and ``(wasm_of_ocaml (enabled_if ...))`` options. This allows for instance to generate one, or the other dependings on a profile:
+
+.. code:: dune
+
+   (env
+    (js-only
+     (wasm_of_ocaml
+      (enabled_if false)))
+    (wasm-only
+     (js_of_ocaml
+      (enabled_if false))))
+
+To be able to invoke the generated code using the same JavaScript script name in all cases, you can add a rule to copy the Wasm launcher script when the js_of_ocaml compilation is disabled.
+
+.. code:: dune
+
+   (rule
+    (action
+     (copy foo.bc.wasm.js foo.bc.js))
+    (enabled_if
+     (= %{profile} wasm-only)))
+
+Separate Compilation
+====================
+
+Dune supports two modes of compilation:
+
+- Direct compilation of a bytecode program to Wasm. This mode allows
+  wasm_of_ocaml to perform whole-program deadcode elimination and whole-program
+  inlining.
+
+- Separate compilation, where compilation units are compiled to Wasm
+  separately and then linked together. This mode is useful during development as
+  it builds more quickly.
+
+The separate compilation mode will be selected when the build profile
+is ``dev``, which is the default. It can also be explicitly specified
+in an ``env`` stanza (see :doc:`/reference/dune/env`) or per executable
+inside ``(wasm_of_ocaml (compilation_mode ...))`` (see :doc:`/reference/dune/executable`)
+
+Sourcemap
+=========
+
+Wasm_of_ocaml can generate sourcemaps for the generated Wasm code.
+By default, they are generated when using the ``dev`` build profile and are not generated otherwise.
+The behavior can explicitly be specified in an ``env`` stanza (see :doc:`/reference/dune/env`)
+or per executable inside ``(wasm_of_ocaml (sourcemap ...))`` (see :doc:`/reference/dune/executable`)
+
+.. _wasm_of_ocaml: https://github.com/ocaml-wasm/wasm_of_ocaml