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Fix side effect detection in optional chains #5589
Fix side effect detection in optional chains #5589
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Thank you for your contribution! ❤️You can try out this pull request locally by installing Rollup via npm install rollup/rollup#gh-5579_improve-chaining-side-effect-detection Notice: Ensure you have installed the latest stable Rust toolchain. If you haven't installed it yet, please see https://www.rust-lang.org/tools/install to learn how to download Rustup and install Rust. or load it into the REPL: |
Performance report!Rough benchmark
Internal benchmark
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Codecov ReportAll modified and coverable lines are covered by tests ✅
Additional details and impacted files@@ Coverage Diff @@
## master #5589 /- ##
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Coverage 99.05% 99.05%
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Files 241 242 1
Lines 9273 9297 24
Branches 2444 2461 17
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Hits 9185 9209 24
Misses 58 58
Partials 30 30 ☔ View full report in Codecov by Sentry. |
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Also, do not unnecessarily deoptimize chain expressions
This PR has been released as part of [email protected]. You can test it via |
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Description
This reworks side effect detection in optional chaining so that in case there is an optional link in a chain that skips the remainder of the chain, any side effects in the start of the chain are still observed.
To do that, I introduce two new methods in chain elements:
getLiteralValueAtPathAsChainElement
is the backbone of the new logic. It behaves the same asgetLiteralValueAtPath
but has an additional Symbol return value if it is called on a skipped chain. It first calls the same method on the previous chain link and short-circuits if that call also returns that Symbol.hasEffectsAsChainElement
similarly works likehasEffects
but first relies ongetLiteralValueAtPathAsChainElement
to detect a broken chain. That way, we can observe all side effects left of the optional link while still skipping all side effects to the right.