webpack-dev-server compiles twice on startup

Bug report

What is the current behavior?

It seems like that the watcher does not work correctly with inline entries like in the following webpack config:

module.exports = {
  entry: {
    main: "./src/index.js",
    inline: "data:text/javascript,"
  },
  mode: "development",
};

Based on the findings of @pvdstel it marks the inline script to be removed and therefore triggers a second compilation.

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

Use the webpack config above and start the webpack-dev-server locally or open this codesandbox which shows the following result:

As you can see watcher.on("initial-missing" triggers because webpack watches inline data: entries:

What is the expected behavior?

The compilation should only trigger once.

Other relevant information:

webpack: “5.11.1”, webpack-cli: “4.3.0”, webpack-dev-server: 4.0.0-beta.0

node: v10.23.0

[sokra]

webpack should not pass data urls to watchpack. This need to be fixed in webpack

[jantimon]

I created a fix which prevents the double compilation here: https://github.com/webpack/watchpack/pull/186

The fix is directly added to watchpack - can you please take a look if that’s a reasonable approach?