Build fails if webpack config exports an array of functions

[danoc]

Describe the bug

webpack-cli@4.0.0 is not able to handle a webpack config that exports an array of functions.

Take this config, for example:

module.exports = [
  () => ({
    entry: "./src/entry1.js",
  }),
  () => ({
    entry: "./src/entry2.js",
  }),
];

It worked in webpack-cli@^3.0.0 but fails in 4.0.0 with this error:

assets by status 0 bytes [cached] 1 asset

ERROR in main
Module not found: Error: Can't resolve './src' in '/Users/doconnor/Thumbtack/webpack5-array-of-functions'

webpack 5.1.0 compiled with 1 error in 120 ms

assets by status 0 bytes [cached] 1 asset

ERROR in main
Module not found: Error: Can't resolve './src' in '/Users/doconnor/Thumbtack/webpack5-array-of-functions'

webpack 5.1.0 compiled with 1 error in 119 ms

webpack-cli@4.0.0 doesn't recognize the entry value and errors saying that it can't find ./src, the webpack default.

What is the current behavior?

Fails to find entrypoint if an array of functions is exported from the webpack config.

To Reproduce

Steps to reproduce the behavior:

1. Clone https://github.com/danoc/webpack-cli-4-array-of-functions
2. Run npm i
3. Run npm run build
4. See error

Expected behavior

Compiles ./src/entry1.js and ./src/entry2.js without errors.

Screenshots

N/A

Please paste the results of webpack-cli info here, and mention other relevant information

System:
  OS: macOS 10.15.7
  CPU: (16) x64 Intel(R) Core(TM) i9-9980HK CPU @ 2.40GHz
  Memory: 3.02 GB / 32.00 GB
Binaries:
  Node: 12.18.3 - ~/.nvm/versions/node/v12.18.3/bin/node
  Yarn: 1.16.0 - /usr/local/bin/yarn
  npm: 6.14.6 - ~/.nvm/versions/node/v12.18.3/bin/npm
Browsers:
  Chrome: 86.0.4240.75
  Firefox: 81.0.1
  Safari: 14.0
Packages:
  webpack: ^5.0.0 => 5.1.0
  webpack-cli: ^4.0.0 => 4.0.0

Additional context

The build works if the webpack config exports a single function or an array of objects. It specifically fails with an array of functions.

Might be related to #1843.

[anshumanv]

Confirmed the issue, thanks for the detailed report!

We will fix it soon.

[alexander-akait]

WIP