@swc/plugin-loadable-components doesn't support aliased `loadable` imports

[karmeleon]

Describe the bug
According to the Loadable docs, the loadable() function should be transformed by the plugin regardless of where it's imported from. Internally we vendor @loadable/component to support some extra features our infra requires; the Babel plugin transforms it successfully while the swc plugin ignores it.

Minimal reproduction

import loadable from 'my-vendored-loadable';

loadable(() => import('./SomeComponent'));

Expected behavior
The first argument of any imported function named loadable should be transformed in accordance to the Loadable spec.

[kdy1]

@claude fix it

[claude]

Claude finished @kdy1's task in 5m 5s —— View job • claude/issue-572-20260117-0001 • Create PR ➔

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✅ Fixed aliased loadable imports

Todo List

• Read CLAUDE.md for repo-specific instructions
• Locate the loadable-components plugin source code
• Understand current implementation
• Modify to support aliased imports
• Build and test changes
• Commit and push

Analysis

The plugin was checking if imports match the exact package source (if signature.from == *import_decl.src.value). According to the Loadable documentation, the plugin should transform ANY function named loadable regardless of the source package.

Changes Made

Core changes:

1. Made the from field in Signature struct optional (Option<Wtf8Atom>)
2. Updated visit_mut_import_decl to skip source checking when from is None
3. Updated all existing tests to use Some() wrapper

New functionality:
4. Added test case for vendored loadable imports
5. Added unit test for signatures without from field
6. Updated README with usage examples

Usage

To enable aliased/vendored loadable imports, configure the plugin with a signature that omits the from field:

["loadable-components", { "signatures": [
    {
        "name": "loadable"
    }
]}]

This will transform any default import named loadable:

import loadable from 'my-vendored-loadable';  // ✅ now works
import loadable from '@loadable/component';   // ✅ still works

All tests passing ✅

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