RE_EXCLUDE class regex doesn't match classes with `extends`, causing false auto-import

[posva]

Description

When a file declares a class with extends and references its own name internally (e.g. Object.setPrototypeOf(this, SystemError.prototype)), unimport incorrectly injects an import for that class, causing an "Identifier has already been declared" error.

Root cause

The RE_EXCLUDE class regex in src/regexp.ts:10 is:

/\bclass\s*([\w$]+)\s*\{/g

This matches class Foo { but not class Foo extends Bar { — the extends Bar part breaks the pattern since it expects \s*\{ immediately after the class name.

As a result, the class name is not removed from the occurrenceMap in detect-regex.ts, and any self-reference within the class body gets auto-imported.

Reproduction

Failing unit test against current main:

it('should not inject import for class with extends that references itself', async () => {
  const { injectImports } = createUnimport({
    imports: [{ name: 'SystemError', from: 'test-id' }],
  })
  const code = `export class SystemError extends Error {
  constructor(message) {
    super(message);
    Object.setPrototypeOf(this, SystemError.prototype);
  }
}`
  expect((await injectImports(code)).code).toBe(code)
})

Expected: no import injected (class is locally declared)
Actual: import { SystemError } from 'test-id'; is injected at the top

Suggested fix

Simplify the regex to only capture the class name without requiring the opening brace:

/\bclass\s+([\w$]+)/g

This correctly handles extends, implements, generics, multiline declarations, etc. since we only need the name.

Downstream

Reported in nuxt/nuxt#26516

[posva]

I only did some testing but I guess that there are other valid names for classes:

class ಠ_ಠ {}