Bug: Sass/Scss partials are not triggering a recompile when using "build --watch"

[segovia94]

When using snowpack build --watch with @snowpack/plugin-sass any change in a sass partial fails to trigger a recompile. This is a hard blocker for doing any sort of development in a traditional site like a CMS.

This is in part due to the sass plugin limiting its partial scanning to isDev which is only set to TRUE when using the dev mode; build --watch sets the isDev to FALSE. Should there be another key passed like isDev that could be specific to the build --watch mode like isWatch?

// During development, we need to track changes to Sass dependencies.
if (isDev) {
  const sassImports = scanSassImports(contents, filePath, fileExt);
  sassImports.forEach((imp) => addImportsToMap(filePath, imp));
}

The second issue appears that when running build --watch the onChange method is never triggered. So even if the first issue is fixed, the changes will still not be triggered. Is there a reason why onChange is not triggered when running build --watch?

[melissamcewen]

Hi @segovia94 , looks like you have an open PR that addresses this. I'll look into getting it merged. For the other issue, do you think this newly merged PR would address it? #2812

[segovia94]

Thanks for looking into it. Unfortunately #2812 didn't fix this particular issue. The merged PR #2792 could in theory help with this, but the main issue is that it is never triggered due to isDev being FALSE during a build --watch. So the partial imports are never scanned.

I tried removing the isDev conditional to force the scan, but they would still not trigger a recompile because the onChange isn't being called to look up what partials have parents needing recompiling.

I'm not really sure where the bug ultimately lies. Should a --watch be passing isDev as TRUE? I see that it does in the run() method, but it does not in the load(). Also, should file changes trigger the onChange event?

I realize that build --watch is a different beast than dev so maybe I'm missing something fundamental about how it is intended to work.

[melissamcewen]

@segovia94 yeah, I'm not sure the answer to this but I'll tag in @drwpow who knows the most about sass of all the maintainers.

[hoangmirs]

It works for me. But I got another error:

I'm not sure why. It's still ok when I use snowpack dev, but snowpack build --watch is failed.
I just use 2 plugins: ["@snowpack/plugin-postcss", "@snowpack/plugin-sass"]

Does anyone have the solution for this?

[segovia94]

As of v3.3.7, this all appears to work now. 😃
3.0.0-3.3.6 throws the error @hoangmirs ran into.
Pre 3.0.0 has the original issue.