Yarn PnP: `require.cache` and `require.extensions` are undefined in dependencies (regression in v22.22.3)

Version

v22.22.3 through v22.23.1

Platform

Darwin LMJ6QJLXY 25.5.0 Darwin Kernel Version 25.5.0: Mon Apr 27 20:41:12 PDT 2026; root:xnu-12377.121.6~2/RELEASE_ARM64_T6050 arm64

Subsystem

No response

What steps will reproduce the bug?

#!/usr/bin/env bash
#
# Save this script to a file named `repro.sh`, then run it:
#
#   bash repro.sh
#
# Without an argument, the script creates `node-yarn-pnp-repro` in the
# directory from which the script is run.
#
# Or choose the directory where the test project will be created:
#
#   bash repro.sh ./my-pnp-repro

set -euo pipefail

repro_dir="${1:-node-yarn-pnp-repro}"

if [[ -e "$repro_dir" ]]; then
  echo "Directory already exists: $repro_dir" >&2
  exit 1
fi

mkdir "$repro_dir"
cd "$repro_dir"

echo "Reproduction directory: $PWD"

cat > package.json <<'EOF'
{
  "name": "node-yarn-pnp-repro",
  "private": true,
  "packageManager": "yarn@4.16.0",
  "dependencies": {
    "autoprefixer": "10.4.2",
    "css-loader": "7.1.4",
    "postcss": "8.4.49",
    "postcss-loader": "8.2.1",
    "style-loader": "4.0.0",
    "tailwindcss": "3.4.15",
    "webpack": "5.108.1",
    "webpack-cli": "5.1.4"
  }
}
EOF

cat > .yarnrc.yml <<'EOF'
nodeLinker: pnp
enableGlobalCache: false
EOF

cat > tailwind.config.js <<'EOF'
module.exports = {
  content: ['./src/**/*.html'],
  theme: { extend: {} },
  plugins: [],
};
EOF

cat > postcss.config.js <<'EOF'
module.exports = {
  plugins: {
    tailwindcss: {},
    autoprefixer: {},
  },
};
EOF

mkdir src

cat > src/style.css <<'EOF'
@tailwind base;
@tailwind components;
@tailwind utilities;
EOF

cat > src/index.html <<'EOF'
<div class="text-red-500">hi</div>
EOF

cat > webpack.config.js <<'EOF'
const path = require('path');

module.exports = {
  mode: 'production',
  entry: './src/style.css',
  output: {
    path: path.resolve(__dirname, 'dist'),
    filename: 'bundle.js',
  },
  module: {
    rules: [
      {
        test: /\.css$/,
        use: ['style-loader', 'css-loader', 'postcss-loader'],
      },
    ],
  },
};
EOF

corepack yarn install
corepack yarn webpack

How often does it reproduce? Is there a required condition?

Every time with nodeLinker: pnp.

The same project succeeds with nodeLinker: node-modules on the same affected Node.js version.

What is the expected behavior? Why is that the expected behavior?

The build should succeed, as it does on Node.js v22.22.2 and earlier, and on Node.js v24.16.0 and later.

require.cache is documented as an object containing cached CommonJS modules.

Packages using Yarn PnP should continue to receive a require function with the standard CommonJS properties, including require.cache and require.extensions.

What do you see instead?

The build fails while webpack-cli loads webpack.config.js:

[webpack-cli] TypeError: Cannot convert undefined or null to object at Function.keys (<anonymous>) at exports.prepare (.../rechoir/index.js:21:14) at loadConfigByPath (.../webpack-cli/lib/webpack-cli.js:...) ...

rechoir calls Object.keys(require.extensions) at that location. Under Yarn PnP on affected Node.js versions, require.extensions is undefined.

The same underlying issue affects packages that access require.cache; for example, code such as delete require.cache[filePath] fails because require.cache is undefined.

Additional information

No response

まず、影響を受ける Node.js バージョンで Yarn Plug'n'Play を使って repro.sh を実行し、nodeLinker: node-modules および一覧にある影響を受けないバージョンと比較します。依存関係用の require 関数がどのように作成されるかを、観測されたエントリーポイントである rechoir/index.js を起点に調べます。webpack のビルドが成功し、依存関係の require 関数が require.cache と require.extensions を公開すれば完了です。