Parcel: Parcel doesn't always pickup source map file correctly

[gregid]

🐛 bug report

My current mono repo set up is as follows

- lib-dist
- lib-src
- app-dist
- app-src

where lib-dist is generated by rollup and app-dist is generated by parcel and has lib-dist as dependency

🎛 Configuration (.babelrc, package.json, cli command)

package.json script:

"app:start": "parcel app-src/index.html --out-dir app-dist",
"build:watch": "rollup --watch --config --sourcemap",

🤔 Expected Behavior

If I make change to app-src or lib-src and save, parcel should pick up changes and reload app in the browser with correct (updated) source map mapping

😯 Current Behavior

If I make change to app-src and save, parcel picks up changes and reloads app in the browser with correct (updated) source map mapping.

But if I make change only to lib-src and save - rollup saves lib-dist and parcel picks up changes for source code and reloads app in the browser but in 50% of cases the source map for the lib-dist will be incorrect i.e.: in console it will show the same line number of the same file, e.g. jquery.js:10873 (last line of jquery in this case) for every printed line

💁 Possible Solution

After making dummy change to app-src the lib-dist is correctly picked up. Since it only happens in about 50% of cases my guess is parcel picks up the source file before the source map is created by rollup.

🔦 Context

I need to make sure that I make some change to app-src every time I make change to lib-src for correctly debugging in browser console which is not ergonomic and time wasting.

💻 Code Sample

🌍 Your Environment

| Software | Version(s) |
| ---------------- | ---------- |
| Parcel | 1.12.4 & 2.0.0
| Node | v13.5.0
| npm/Yarn | 6.13.4
| rollup | 2.13.1
| Operating System | Win10x64

[gregid]

I tried installing parcel2 and so far it seems it works correctly. Will see in the next few days if the problem appears.

[gregid]

Unfortunately with parcel2 (2.0.0-nightly.280) the problem is even bigger - it completely ignores source map for my rollup generated file.

EDIT: the same is happening with 2.0.0-alpha.3.2 so I must have missed this when I wrote previous reply.

[gregid]

I have created sample project showing the problem:
https://github.com/gregid/rollup-lib-parcel-app

[mischnic]

Loading source maps from via sourceMappingURL of input assets isn't implemented yet for Parcel 2

[gregid]

@mischnic thanks for the update - is there any single place where current status of Parcel 2 (implementation wise) is so I wouldn't raise unnecessary issues in my further testing of parcel2?

[mischnic]

issues in my further testing of parcel2?

No, keep them coming 😄

[gregid]

Q: Is this PR: #4813 on the roadmap to next release? Is my understanding correct it should address the issue?

[DeMoorJasper]

@gregid it is, someone just needs to review it and then it should be on the next release

[gregid]

That's great, looking forward to testing it on nightly build once ready!

[mischnic]

someone just needs to review it

And someone to fix CI 😉

[gregid]

sorry to be PITA but I've noticed the CI has been fixed for few days now and I am checking the progress few times a day (I need it a lot) hoping tomorrow is the day I could use it on nightly build...

[gregid]

Other than failing to build on incorrect sourcemap URL #5031 the initial problem - randomly picking up external sourcemaps seems to be gone with the new PR, I will continue to test it a bit further and if it will continue to work will close this issue.

[gregid]

Haven't failed so far, closing the issue.