@snowpack/plugin-svelte sourcemap support for preprocessors

[probablykasper]

@snowpack/plugin-svelte supports source maps for .svelte files, but it seems like those don't support svelte-preprocess.

svelte-preprocess has a sourceMap: true option, so I imagine it should be possible to combine this with the .svelte source maps.

Are there any major roadblocks preventing this from being done?

[probablykasper]

@FredKSchott Sorry if the mention is unwanted, but do you have any thoughts on this?

[probablykasper]

@FredKSchott @matthewp @melissamcewen Hey, any word on this at all?

[matthewp]

Hi @probablykasper, I'm not too familiar with this plugin, is svelte-preprocess something the svelte plugin would have to start using? Or something we just need to flip an option on? If you could describe more what needs to be done to make this happen that would help. I would suggest sending a PR but I also want to be respectful of your time and not have you make a big change that might not get accepted.

[probablykasper]

@matthewp Thanks for responding! svelte-preprocess is already used by @snowpack/plugin-svelte to preprocess languages like TypeScript, Sass, etc inside .svelte files. svelte-preprocess does support generating source maps using the sourceMap option, but Snowpack doesn't seem to use them.

I tried enabling source maps by specifying the plugin like this in snowpack.config.js:
['@snowpack/plugin-typescript', { preprocess: { sourceMap: true } }],

I'm not really sure what would have to be done to support it, or whether it's trivial or not.

[probablykasper]

@matthewp Hey, any thoughts so far?

Is this something that could have an issue created for it? I feel like either this should be supported, or there should be a note stating that Svelte Preprocess support is incomplete.