From 999efeba9258642dd85a1a544801f7218f21426f Mon Sep 17 00:00:00 2001
From: Jordan Harband <ljharb@gmail.com>
Date: Wed, 6 May 2026 11:48:25 -0700
Subject: [PATCH 1/2] module: exclude node:ffi from builtinModules when flag is
 disabled

Module.builtinModules is supposed to only list modules
that are accessible to user code.
node:ffi requires --experimental-ffi to be required,
so filter it out when the flag is not set,
mirroring the existing handling for --experimental-quic.

Refs: https://github.com/nodejs/node/pull/63137#issuecomment-4390371187

Signed-off-by: Jordan Harband <ljharb@gmail.com>
---
 lib/internal/modules/cjs/loader.js | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/lib/internal/modules/cjs/loader.js b/lib/internal/modules/cjs/loader.js
index 0b59d7e7a0f911..c9cf6a0f82bb86 100644
--- a/lib/internal/modules/cjs/loader.js
+++ b/lib/internal/modules/cjs/loader.js
@@ -490,6 +490,9 @@ function initializeCJS() {
   if (!getOptionValue('--experimental-quic')) {
     modules = modules.filter((i) => i !== 'node:quic');
   }
+  if (!getOptionValue('--experimental-ffi')) {
+    modules = modules.filter((i) => i !== 'node:ffi');
+  }
   Module.builtinModules = ObjectFreeze(modules);
 
   initializeCjsConditions();

From cc2a34658b7e300cafd71cc83cab46d8a4c46505 Mon Sep 17 00:00:00 2001
From: Antoine du Hamel <duhamelantoine1995@gmail.com>
Date: Wed, 6 May 2026 21:33:12 +0200
Subject: [PATCH 2/2] fixup! module: exclude node:ffi from builtinModules when
 flag is disabled

---
 test/ffi/test-ffi-module.js | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/test/ffi/test-ffi-module.js b/test/ffi/test-ffi-module.js
index 1cd2b840097d6b..573c5e7ce5947b 100644
--- a/test/ffi/test-ffi-module.js
+++ b/test/ffi/test-ffi-module.js
@@ -1,6 +1,7 @@
 // Flags: --experimental-ffi
 'use strict';
 const common = require('../common');
+const { spawnSyncAndAssert } = require('../common/child_process');
 const assert = require('node:assert');
 const { spawnSync } = require('node:child_process');
 const { test } = require('node:test');
@@ -32,17 +33,16 @@ test('ffi builtin is unavailable when disabled', () => {
 });
 
 test('ffi builtin is listed', () => {
-  const { stdout, stderr, status, signal } = spawnSync(process.execPath, [
-    '-p',
-    'require("node:module").builtinModules.includes("node:ffi")',
-  ], {
-    encoding: 'utf8',
-  });
-
-  assert.strictEqual(stdout.trim(), 'true');
-  assert.strictEqual(stderr, '');
-  assert.strictEqual(status, 0);
-  assert.strictEqual(signal, null);
+  for (const [flag, stdout] of Object.entries({
+    '--experimental-ffi': 'true\n',
+    '--no-experimental-ffi': 'false\n',
+  })) {
+    spawnSyncAndAssert(process.execPath, [
+      flag,
+      '-p',
+      'require("node:module").builtinModules.includes("node:ffi")',
+    ], { stdout });
+  }
 });
 
 test('ffi can be imported from ESM', () => {