From 85902e938cc9b5f871bd734ddbcadf3f8809de87 Mon Sep 17 00:00:00 2001
From: Hugo Heuzard <hugo.heuzard@gmail.com>
Date: Mon, 1 Dec 2025 16:38:48 +0100
Subject: [PATCH 1/2] WIP

---
 .github/workflows/js_of_ocaml.yml   | 4 ----
 .github/workflows/lint.yml          | 3 ---
 .github/workflows/wasm_of_ocaml.yml | 4 ----
 bench.Dockerfile                    | 1 -
 dune-project                        | 2 +-
 wasm_of_ocaml-compiler.opam         | 2 +-
 6 files changed, 2 insertions(+), 14 deletions(-)

diff --git a/.github/workflows/js_of_ocaml.yml b/.github/workflows/js_of_ocaml.yml
index 3a13311769..f18cc5cfaf 100644
--- a/.github/workflows/js_of_ocaml.yml
+++ b/.github/workflows/js_of_ocaml.yml
@@ -139,10 +139,6 @@ jobs:
         with:
           token: ${{ github.token }}
 
-      - name: Install faked binaryen-bin package
-        # It's faster to use a cached version
-        run: opam install --fake binaryen-bin
-
       - run: opam install . --best-effort --solver builtin-mccs+glpk
         if: ${{ matrix.skip-test }}
 
diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
index 820f7c507f..9e304b8ed4 100644
--- a/.github/workflows/lint.yml
+++ b/.github/workflows/lint.yml
@@ -25,9 +25,6 @@ jobs:
         uses: Aandreba/setup-binaryen@v1.0.0
         with:
           token: ${{ github.token }}
-      - name: Install faked binaryen-bin package
-        # It's faster to use a cached version
-        run: opam install --fake binaryen-bin
       - uses: ocaml/setup-ocaml/lint-opam@v3
 
   lint-fmt:
diff --git a/.github/workflows/wasm_of_ocaml.yml b/.github/workflows/wasm_of_ocaml.yml
index 09dfe1991c..4422ee09c3 100644
--- a/.github/workflows/wasm_of_ocaml.yml
+++ b/.github/workflows/wasm_of_ocaml.yml
@@ -98,10 +98,6 @@ jobs:
         with:
           token: ${{ github.token }}
 
-      - name: Install faked binaryen-bin package
-        # It's faster to use a cached version
-        run: opam install --fake binaryen-bin
-
       # Work-around a race between reinstalling mingw-w64-shims
       # (because of conf-pkg-config optional dep) and installing other
       # packages that implicitly depend on mingw-w64-shims.
diff --git a/bench.Dockerfile b/bench.Dockerfile
index e7712c34eb..c75e9ce0a8 100644
--- a/bench.Dockerfile
+++ b/bench.Dockerfile
@@ -22,7 +22,6 @@ ENV BINARYEN=binaryen-$BINARYEN_VERSION
 RUN curl -Lq https://github.com/WebAssembly/binaryen/releases/download/$BINARYEN_VERSION/$BINARYEN-x86_64-linux.tar.gz \
   | tar zxf -
 ENV PATH="/bench-dir/$BINARYEN/bin:$PATH"
-RUN opam install --fake binaryen-bin
 
 # Jane Street opam packages
 RUN mkdir janestreet \
diff --git a/dune-project b/dune-project
index 45b9ce66de..ce9df24ffb 100644
--- a/dune-project
+++ b/dune-project
@@ -150,7 +150,7 @@
   menhirLib
   menhirSdk
   (yojson (>= 2.1))
-  binaryen-bin)
+  conf-binaryen)
  (depopts
   ocamlfind)
  (conflicts
diff --git a/wasm_of_ocaml-compiler.opam b/wasm_of_ocaml-compiler.opam
index 1a2af784a3..8bf2ff2560 100644
--- a/wasm_of_ocaml-compiler.opam
+++ b/wasm_of_ocaml-compiler.opam
@@ -26,7 +26,7 @@ depends: [
   "menhirLib"
   "menhirSdk"
   "yojson" {>= "2.1"}
-  "binaryen-bin"
+  "conf-binaryen"
   "odoc" {with-doc}
 ]
 depopts: ["ocamlfind"]

From 612c3402539dde2156ecb28b01284fc6b3e09613 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=A9r=C3=B4me=20Vouillon?= <jerome.vouillon@gmail.com>
Date: Thu, 4 Dec 2025 13:31:46 +0100
Subject: [PATCH 2/2] Document Binaryen dependency

---
 README.md                 | 6 ++++--
 manual/wasm_overview.wiki | 3 +++
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index cc82d4a1c4..2553353e33 100644
--- a/README.md
+++ b/README.md
@@ -30,9 +30,11 @@ Js_of_ocaml is composed of multiple packages:
 
 ## Requirements
 
-See
+See the
 [opam](https://github.com/ocsigen/js_of_ocaml/blob/master/js_of_ocaml-compiler.opam)
-file for version constraints.
+files for version constraints.
+
+wasm_of_ocaml-compiler additionally depends on a system installation of binaryen (version 119 or later)
 
 ## Supported engines
 
diff --git a/manual/wasm_overview.wiki b/manual/wasm_overview.wiki
index 2c8a56d137..32950ff06f 100644
--- a/manual/wasm_overview.wiki
+++ b/manual/wasm_overview.wiki
@@ -12,6 +12,9 @@ The compiler is provided by the wasm_of_ocaml-compiler package. The <<a_manual c
 The easiest way to install wasm_of_ocaml is to use opam.
 {{{opam install wasm_of_ocaml-compiler js_of_ocaml js_of_ocaml-ppx js_of_ocaml-lwt}}}
 
+Binaryen version 119 or later is required. The opam command above will
+install it automatically if needed.
+
 == Usage ==
 
 Your program must first be compiled using the OCaml bytecode compiler