What is the current behavior?

Executing webpack with a ES6+ config file (webpack.config.babel.js) whilst using Babel 7 leads to a SyntaxError being reported e.g.

$ webpack --env.production
<OMITTED>/webpack.config.babel.js:1
(function (exports, require, module, __filename, __dirname) { import path from 'path'
                                                              ^^^^^^

SyntaxError: Unexpected token import

If the current behavior is a bug, please provide the steps to reproduce.

1. Install the latest webpack and the latest @babel/core & @babel/preset-env (e.g 7.0.0-beta.32)

2. Create a webpack.config.babel.js with ES6+ syntax e.g.

   echo "import path from 'path'" > webpack.config.babel.js
   

   Note: For illustrative purposes only, this obviously doesn't produce a valid webpack config, but it's sufficient to recreate the issue.

3. Create a .babelrc with the env preset:

   echo "{\"presets\":[\"@babel/env\"]}" > ./.babelrc
   

4. Run webpack e.g.

   webpack
   

What is the expected behavior?

Babel to to be executed on webpack.config.babel.js before Node executes the file.

Following the steps above you're expecting a webpack specific error regarding an invalid configuration:

<OMITTED>/node_modules/webpack/bin/convert-argv.js:507
				throw new Error("'output.filename' is required, either in config file or as --output-filename");

Please mention other relevant information such as the browser version, Node.js version, webpack version and Operating System.

webpack: 3.8.1
@babel/core: 7.0.0-beta.32
@babel/preset-env: 7.0.0-beta.32

What I'm assuming is happening is that Webpack is looking for the presence of a babel-core package, can't find it, so proceeds without using babel. Babel 7 has scoped packages, the new package is @babel/core.