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Backport #2398: fix(swc-plugin): count destructuring-default references in DCE usage analysis - #2465
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…analysis (#2398) The DCE usage collector skipped the entire variable name pattern when visiting a `VarDeclarator` (to avoid marking the binding name as "used"). But default-value initializers inside destructuring patterns live in that pattern — e.g. the `TTL` in `const { ttl = TTL } = options;` — so those references were invisible to the collector. A module-scope `const` referenced only through such a default was treated as unused and stripped, while the surviving code kept reading it, producing a runtime `ReferenceError` when the default fired. Traverse the default-value initializer expressions (and computed keys) within destructuring patterns while still not marking the binding names themselves, so the referenced declaration is preserved. Function-parameter defaults were already covered (params are visited in full). Fixes#2396. Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com> Signed-off-by: Pranay Prakash <pranay.gp@gmail.com>
🦋 Changeset detectedLatest commit: 452d1ee The changes in this PR will be included in the next version bump. This PR includes changesets to release 17 packages
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TooTallNate added a commit
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Jun 17, 2026
…default DCE test The #2398 backport (#2465) added the destructuring-default-references-module-const fixture but committed output-step.js verbatim from main and omitted output-client.js entirely. Stable's SWC plugin emits a different step-registration shape (registerStepFunction import vs. inline IIFE) and has less aggressive DCE (the truly-unused UNUSED const is not stripped), so the copied output-step.js did not match stable's actual output and the required output-client.js was missing. Regenerate both fixture outputs against stable's plugin so the client_mode and step_mode fixture tests pass. The regression being tested still holds: TTL and RETRIES (referenced only via destructuring defaults) are preserved in all modes. Signed-off-by: Nathan Rajlich <n@n8.io>
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Automated backport of #2398 to
stable(backport job run).AI recommendation: This is a self-contained bug fix to the SWC plugin's DCE usage collector, and the buggy
ComprehensiveUsageCollector::visit_mut_var_declaratorcode (with its "Only visit the initializer" comment) is present verbatim onstable, so the runtimeReferenceErrorit fixes affectsstabletoo. It touches only actively-maintained paths (transform/src/lib.rs,spec.md, test fixtures, plus a changeset) and does not build on anymain-only APIs.Merge conflicts were resolved by AI (opencode with
anthropic/claude-opus-4.8). Please review the conflict resolution carefully before merging.