Feat: support new resolving import at-rules

[fyangstudio]

https://github.com/webpack-contrib/sass-loader#resolving-import-at-rules

Using ~ is deprecated and can be removed from your code (we recommend it), but we still support it for historical reasons. Why can you remove it? The loader will first try to resolve @import as a relative path. If it cannot be resolved, then the loader will try to resolve @import inside node_modules.

Support VS Code DefinitionProvider find right package like:

@import "bootstrap";
@import "~bootstrap";

[fyangstudio]

@aeschli

[aeschli]

The loader will first try to resolve @import as a relative path. If it cannot be resolved, then the loader will try to resolve @import inside node_modules

The looking up of an import in node_modules, Is this something webpack does, or SCSS?

[fyangstudio]

The loader will first try to resolve @import as a relative path. If it cannot be resolved, then the loader will try to resolve @import inside node_modules

The looking up of an import in node_modules, Is this something webpack does, or SCSS?

@aeschli Webpack and Sass are both mentioned that imports will always be resolved relative to the current file first, see:

Webpack: https://github.com/webpack-contrib/sass-loader#resolving-import-at-rules
Sass: https://sass-lang.com/documentation/at-rules/import#load-paths

This PR support node module resolution without ~.

PS: using ~ is work too

[aeschli]

Thanks @fyangstudio.
I wonder if we should only enable this for SCSS. Right now, that change would enable the extended resolving also for LESS and CSS.
For CSS there's the css-loader. If I get this right, it still requires '~'.

Also, it would be nice to have tests as well.

[fyangstudio]

Thanks @fyangstudio. I wonder if we should only enable this for SCSS. Right now, that change would enable the extended resolving also for LESS and CSS. For CSS there's the css-loader. If I get this right, it still requires '~'.

Also, it would be nice to have tests as well.

'~' is deprecated in Less too, see https://github.com/webpack-contrib/less-loader#imports

I have changed it only enable new rule for Sass and Less.

@aeschli Please check.

By the way I think css-loader will support the new resolving import at-rules soon.

[fyangstudio]

@aeschli if this PR have any questions, please let me know.

[aeschli]

I polished the check whether to resolve module references (6e64249)

All looks good now, thanks @fyangstudio !