fix: narrow the export presence guard detection#20561
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alexander-akait merged 2 commits intomainfrom Mar 2, 2026
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🦋 Changeset detectedLatest commit: c1f69b1 The changes in this PR will be included in the next version bump. This PR includes changesets to release 1 package
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Merging this PR will degrade performance by 20.42%
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Mar 2, 2026
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Summary
What kind of change does this PR introduce?
This PR narrows export presence guard detection to explicit existence checks on namespace imports only, i.e. patterns like
"x" in ns.Previously, export presence guard detection covered a broader set of patterns, such as
if (x),if (ns.x),if (x !== undefined),if (ns.x !== undefined), and similar cases. However, in all of these cases, thexexport has already been used in the condition itself. That means the access must still be treated as a normal usage and should continue to participate in the export presence diagnostics.As a result, for non-namespace imports (for example, named imports or default imports), an import binding references a missing export from a module, a linking error should still be issued, even if its real usage is inside a guard such as
import {x} from "./ns"; if (x) { fn(x) }, because the binding itself has already been used in the if condition.This keeps the guard semantics focused on export existence rather than value checks, to better matches behavior in some runtimes and preserves the existing
undefined + warning/errorresults covered in the https://sokra.github.io/interop-test/by-syntaxDid you add tests for your changes?
Yes
Does this PR introduce a breaking change?
No
If relevant, what needs to be documented once your changes are merged or what have you already documented?
No
Use of AI
No