fix: avoid false positives on import/export aliases#3
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albertodeago merged 1 commit intoMay 12, 2026
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…iases
The previous pattern `$expr as $type` over-matches because the `as`
token appears in many AST constructs, not just `TsAsExpression`:
- `import { foo as bar } from ...` (JsNamedImportSpecifier)
- `import * as ns from ...` (JsNamespaceImportSpecifier)
- `export { foo as bar }` (JsExportNamedFromSpecifier)
The exclusion `! $expr <: within \`import $_ from $_\`` only
covered single-specifier default imports, leaving multi-specifier named
imports and namespace imports as false positives.
biome 2.4.9 fixed a metavariable matching bug
(biomejs/biome#9586) that previously masked the issue, so the false
positives now surface for any user of biome >= 2.4.9.
Constrain the matched node to `TsAsExpression()` so only genuine TS
type assertions are flagged.
Closes albertodeago#2
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Author
|
Hi @albertodeago — gentle ping on this one when you get a chance 🙏 This fixes a real regression that surfaces for any user on biome >= 2.4.9 (since biomejs/biome#9586 fixed the metavariable matching that was previously masking the issue). Happy to address any feedback if there's anything you'd like changed. Thanks for maintaining this plugin! |
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|
hey @maroKanatani |
albertodeago
approved these changes
May 12, 2026
albertodeago
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Amazing work, thanks for the fix!
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Fixes #2.
$expr as $typematches any use of theastoken, including importaliases (
import { foo as bar }), namespace imports (import * as ns),and export aliases (
export { foo as bar }). The existing guard! $expr <: within \import $_ from $_`` only handled single-specifierimports and left the rest as false positives.
This was harmless until biome 2.4.9, which fixed metavariable matching
inside
import { ... }/export { ... }clauses(biomejs/biome#9586). After that fix the broken guard started firing.
The fix is to constrain on
TsAsExpression()instead: