feat: watch mode config change

[evenstensberg]

What kind of change does this PR introduce? Fixes https://github.com/webpack/webpack-cli/issues/15

Did you add tests for your changes? No If relevant, did you update the documentation? N/A Summary Need to check if CLIplugin is added to the config, otherwise there will be a memory leak

Does this PR introduce a breaking change?

No Other information N/A

[webpack-bot]

@evenstensberg Thanks for your update.

I labeled the Pull Request so reviewers will review it again.

@alexander-akait Please review the new changes.

[evenstensberg]

PTAL

[evenstensberg]

@alexander-akait you have the source, maybe you can have a look at it?

[evenstensberg]

Some points:

1. We only have to worry about the compiler re-rednering after a config change is noticed
2. We only have access to the configuration at this level

Due this, I think this is the right level of abstraction. Since the CLI is the one that reads a config, I think this is where we naturally add this feature. I don't understand why webpack itself should re-validate a config, core should only be worried about doing a compilation.

WDYT?

[alexander-akait]

@evenstensberg Because only webpack knows about dependencies

[evenstensberg]

We just want config changes, not dependency changes. Watchmode + watch a config file

[alexander-akait]

In this case we don't look at import/require inside webpack.config.js/package.json and etc, so reload will not work for many cases

[evenstensberg]

The watch API will sniff those changes if the text inside the config changes. this is what we want

[alexander-akait]

We should watch dependencies too like package.json/import/require and etc

[evenstensberg]

No need, if we refer to the original issue

[alexander-akait]

It is require to right implementation

[evenstensberg]

PTAL. Uses https://github.com/evenstensberg/watch-traverse

[alexander-akait]

I wanted to close it, because it is invalid, we need to improve it on webpack side, we need:

• move buildDependecies from options.cache.buildDependencies to top options (it will be useful for any configuration, not only for webpack itself)
• implement watchRun hook and get files from compilation.modifiedFiles, if we have confiugration file there restart our CLI