Module dependencies set in buildModule hook are getting reset during the build

Bug report

What is the current behavior?

I’m trying to modify the source of the module based on this comment

So my code looks like this:

compilation.hooks.buildModule.tap('MyPlugin', (module) => {
	module.addDependency(new MyDependency())
})

But it’s doesn’t work because in the build method webpack resets dependencies of module https://github.com/webpack/webpack/blob/2151f56ae73b35722c56432c9b34820626d72e53/lib/NormalModule.js#L879

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

Clone https://github.com/7rulnik/webpack-repro-13361 and run yarn && yarn webpack

What is the expected behavior?

I don’t quite follow the logic of clearDependenciesAndBlocks, but I thing that it should contain check for dependencies.length

Other relevant information: webpack version: 5.36.2 Node.js version: v14.15.4 Operating System: MacOS 11.3 M1

[7rulnik]

@alexander-akait the only reason why I decided to create an issue, not a question in discussions, because that implementation based on Tobias’s own comment. Also, it works in webpack 4 and I didn’t find anything related to this change in changelog. So this is why I raised this issue.

So basically I want to modify a source of modules. I added repro into main post https://github.com/7rulnik/webpack-repro-13361

I also understand that this can be worked around by adding a dependency to parser.hooks, for example, ConstDependency.

[michenly]

For anyone who ran into similar problem and wondering how parser.hooks can be use to modify module. The trick is accessing module using parser.state.module inside a parser.hooks.program.tap(...)