Extends and standardize dependency message

result.messages.push({ type: 'dependency', file }) is a special API for plugin developers to tell about used files to PostCSS runner. The most popular way to use it is a watch mode.

But seems like we need to improve this message:

1. Just the file path is not enough. For instance, postcss-mixins accept glob pattern.
2. Seems like webpack’s css-loader needs more types: missing, build, context and regular dependencies. I do not like separated types like build-dependency. I think it will be better to use { type: 'dependency', build: true }

Questions:

1. @mischnic @RyanZim Can every runner support glob-pattern for file watch?
2. @alexander-akait can you explain what is build/context/missed dependency? It maybe a good idea to use these messages in other builders too.

[ai]

I think for string better to use dir-dependency

OK. It will be more CSS-ish.

maybe for dependency use file-dependency to avoid small misleading

We need compatibility with old API

[ai]

We added optional glob parameter to dir-dependnecy: { type: 'dir-dependency', dir: '/imported', glob: '**/*.css', }

https://github.com/postcss/postcss/pull/1590