fix(isolated-declarations): incorrectly dropping namespace even if it is being referenced

[Copilot]

When an exported type references a namespaced type (e.g., export type A = Foo.Bar), the namespace declaration was being dropped from the output, causing the type reference to resolve to any.

// Input
export type A = Foo.Bar;

namespace Foo {
  export type Bar = "bar"
}

// Before: namespace dropped
export type A = Foo.Bar;

// After: namespace included
export type A = Foo.Bar;
declare namespace Foo {
  type Bar = "bar";
}
export {};

Changes

• declaration.rs: Changed namespace inclusion check from has_value_reference() to has_reference() to account for type-position references. This aligns with enum handling, which also uses has_reference() since both can serve dual roles as types and values.

• Test coverage: Added test cases for simple, nested, and multiple namespace references in various type positions (aliases, unions, interfaces).

Technical Details

Namespaces are bound with KindFlags::All (both type and value), but the transform logic was only checking for value references. Type references like Foo.Bar are tracked as KindFlags::Type through visit_ts_type_name(), so the previous check excluded legitimately referenced namespaces.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Isolated declarations emit drops namespaced types</issue_title>
<issue_description>When an exported type references a namespaced one, the namespace is not included in the output.

// This ends up being `any` 
export type A = Foo.Bar;

namespace Foo {
  export type Bar = "bar"
}

emits:

// This ends up being `any`
export type A = Foo.Bar;

playground</issue_description>

<agent_instructions>We should look into the oxc_isolated_declaration crate to fix this bug.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes Isolated declarations emit drops namespaced types #15028

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[codspeed-hq]

CodSpeed Performance Report

Merging #15123 will not alter performance

_{Comparing copilot/fix-namespaced-type-export (2af8192) with main (d78419f)¹}

Summary

✅ 33 untouched
⏩ 4 skipped²

Footnotes

1. No successful run was found on main (e25bc6f) during the generation of this report, so d78419f was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

2. 4 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[Copilot]

Pull Request Overview

This PR fixes an issue where TypeScript namespaces were incorrectly excluded from generated declaration files when they were only referenced in type positions (e.g., Foo.Bar in type aliases). The change ensures namespaces are included when referenced as either types or values.

Key changes:

• Updated namespace reference checking from value-only to all references (type and value)
• Added test cases for namespace type references in various scenarios

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
crates/oxc_isolated_declarations/src/declaration.rs	Changed namespace reference check from has_value_reference to has_reference to include both type and value references
crates/oxc_isolated_declarations/tests/snapshots/shadowed.snap	Updated snapshot showing namespace now correctly included when referenced in type position
crates/oxc_isolated_declarations/tests/snapshots/namespace-type-reference.snap	New test snapshot for simple namespace type reference scenario
crates/oxc_isolated_declarations/tests/snapshots/namespace-type-reference-complex.snap	New test snapshot for complex namespace type reference scenarios
crates/oxc_isolated_declarations/tests/fixtures/namespace-type-reference.ts	New test fixture for basic namespace type reference
crates/oxc_isolated_declarations/tests/fixtures/namespace-type-reference-complex.ts	New test fixture covering various namespace reference patterns

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