Firestore: fix source maps that incorrectly referenced back into the bundle itself

[dconeybe]

Some of the bundles produced by Firestore's rollup pipeline generated source maps that incorrectly linked into yet another minified, mangled JavaScript file, instead of back into the original source code. This rendered the source maps useless because there was no way to get back to the original source code.

The root problem was that the rollup pipeline is done in a two step process. Step 1 produces a minified, mangled bundle and step 2 takes that minified, mangled bundle and produces other minified, mangled bundles. Surprisingly, some of the source maps did indeed map back to the original source code (i.e. index.esm5.js.map and index.node.cjs.js) but others referenced the intermediate minified, mangled bundle (i.e. index.esm2017.js, index.cjs.js, index.node.mjs, and index.browser.esm2017.js).

The "good" source maps, it was discovered, worked correctly by using the rollup-plugin-sourcemaps plugin, which "passes through" the source maps of intermediate files. So the fix was easy: just use the rollup-plugin-sourcemaps plugin in the other bundles as well. Sure enough, that is the fix in this PR and the source maps are good again.

[changeset-bot]

🦋 Changeset detected

Latest commit: 90b3e0c

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 3 packages

Name	Type
@firebase/firestore	Patch
firebase	Patch
@firebase/firestore-compat	Patch

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[google-oss-bot]

Size Report ¹

Affected Products

No changes between base commit (85ccb2e) and merge commit (d04a17a).

Test Logs

• Base (85ccb2e): https://github.com/firebase/firebase-js-sdk/actions/runs/5346925293
• Merge (d04a17a): https://github.com/firebase/firebase-js-sdk/actions/runs/5348577425

1. https://storage.googleapis.com/firebase-sdk-metric-reports/1Tn2VQP234.html

[google-oss-bot]

Size Analysis Report ¹

Affected Products

No changes between base commit (85ccb2e) and merge commit (d04a17a).

Test Logs

• Base (85ccb2e): https://github.com/firebase/firebase-js-sdk/actions/runs/5346925293
• Merge (d04a17a): https://github.com/firebase/firebase-js-sdk/actions/runs/5348577425

1. https://storage.googleapis.com/firebase-sdk-metric-reports/P8VXyW2E4b.html

[dconeybe]

@hsubox76 Posted this question to me in a different forum, and I'm moving the discussion here to keep it all together.

You said the esm5 bundles previously worked, both of them? I see the Firestore Lite rollup config already had sourcemaps() in the ESM5 config (my comment there was about why it needed to be reordered), but I don't see it in the ESM5 config for non-lite. Did it work anyway? Does it need to be added there in this PR (line 146/150 in the PR in rollup.config.js)?

Good question. The sourcemaps() is there for the esm5 bundles for the non-lite SDK... it's just tucked away. The "plugins" list for the esm5 bundle contains ...util.es2017ToEs5Plugins(/* mangled= */ true):

firebase-js-sdk/packages/firestore/rollup.config.js

Line 148 in 85ccb2e

...util.es2017ToEs5Plugins(/* mangled= */ true),

That es2017ToEs5Plugins() function adds the sourcemaps() here:

firebase-js-sdk/packages/firestore/rollup.shared.js

Line 305 in 85ccb2e

sourcemaps()

.

[hsubox76]

Thanks for the explanation!

[dconeybe]

This was included in the v10.0.0 release: https://firebase.google.com/support/release-notes/js#version_1000_-_july_6_2023