fix: add proper babel 7 support (#6)

Author: sapphi-red

.github/workflows/ci.yml

@@ -54,17 +54,52 @@ jobs:
       - name: Test
         run: pnpm run test
 
+  test-babel7:
+    timeout-minutes: 20
+    runs-on: ubuntu-latest
+    name: 'Test: babel 7 compat'
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v6
+
+      - name: Install pnpm
+        uses: pnpm/action-setup@41ff72655975bd51cab0327fa583b6e92b6d3061 # v4.2.0
+
+      - name: Set node version to 24
+        uses: actions/setup-node@v6
+        with:
+          node-version: 24
+          cache: 'pnpm'
+
+      - name: Override @babel/core to v7
+        run: yq -i '.overrides."@babel/core" = "^7.29.0"' pnpm-workspace.yaml
+
+      - name: Install deps
+        run: pnpm install --no-frozen-lockfile
+
+      - name: Install @babel/core v7 types
+        run: pnpm add -Dw @types/babel__core@^7.20.5
+
+      - name: Build
+        run: pnpm run build
+
+      - name: Test
+        run: pnpm run test
+
+      - name: Lint (type check)
+        run: pnpm run lint
+
   test-passed:
     if: (!cancelled() && !failure())
-    needs: test
+    needs: [test, test-babel7]
     runs-on: ubuntu-latest
     name: Build & Test Passed or Skipped
     steps:
       - run: echo "Build & Test Passed or Skipped"
 
   test-failed:
     if: (!cancelled() && failure())
-    needs: test
+    needs: [test, test-babel7]
     runs-on: ubuntu-latest
     name: Build & Test Failed
     steps:

packages/babel/src/babelCompat.ts

@@ -0,0 +1,37 @@
+/**
+ * A type compatibility layer for Babel 7 and 8.
+ */
+
+export * from '@babel/core'
+
+import * as babel from '@babel/core'
+
+// https://github.com/type-challenges/type-challenges/issues/29285
+type IsAny<T> = boolean extends (T extends never ? true : false) ? true : false
+
+// @ts-ignore -- InputOptions doesn't exist in Babel 7
+type InputOptions8 = babel.InputOptions
+// @ts-ignore -- PresetItem doesn't exist in Babel 7
+type PresetItem8 = babel.PresetItem
+// @ts-ignore -- PluginObject doesn't exist in Babel 7
+type PluginObject8<T> = babel.PluginObject<T>
+// @ts-ignore -- FileResult doesn't exist in Babel 7
+type FileResult8 = babel.FileResult
+
+// @ts-ignore -- TransformOptions doesn't exist in Babel 8
+type TransformOptions = babel.TransformOptions
+// @ts-ignore -- PluginObj doesn't exist in Babel 8
+type PluginObj<T> = babel.PluginObj<T>
+// @ts-ignore -- BabelFileResult doesn't exist in Babel 8
+type BabelFileResult = babel.BabelFileResult
+
+export type InputOptions = IsAny<InputOptions8> extends false ? InputOptions8 : TransformOptions
+export type PresetItem = IsAny<PresetItem8> extends false ? PresetItem8 : babel.PluginItem
+export type PluginObject<T = babel.PluginPass> =
+  IsAny<PluginObject8<T>> extends false ? PluginObject8<T> : PluginObj<T>
+export type FileResult = IsAny<FileResult8> extends false ? FileResult8 : BabelFileResult
+
+export const loadOptionsAsync: (
+  options?: InputOptions,
+  // oxlint-disable-next-line typescript/no-unsafe-type-assertion
+) => Promise<InputOptions & { plugins: babel.PluginItem[] }> = (babel as any).loadOptionsAsync

packages/babel/src/filter.ts

@@ -1,7 +1,7 @@
 import type { HookFilter, GeneralHookFilter, ModuleTypeFilter } from 'rolldown'
 import type { ResolvedPluginOptions } from './options'
 import type { RolldownBabelPresetItem, RolldownBabelPreset } from './rolldownPreset'
-import type { InputOptions } from '@babel/core'
+import type { InputOptions } from './babelCompat'
 import { arrayify } from './utils'
 
 type ConfigApplicableTest = Exclude<InputOptions['include'], undefined>

packages/babel/src/index.test.ts

@@ -1,11 +1,12 @@
 import { assert, describe, expect, test } from 'vitest'
 import babelPlugin from './index.ts'
-import * as babel from '@babel/core'
+import * as babel from './babelCompat.ts'
 import { rolldown, type OutputChunk } from 'rolldown'
 import { build as viteBuild, createBuilder, type Rollup } from 'vite'
 import path from 'node:path'
 import { collectOptimizeDepsInclude, type PluginOptions } from './options.ts'
 import type { RolldownBabelPreset } from './rolldownPreset.ts'
+import { stripVTControlCharacters } from 'node:util'
 
 test('plugin works', async () => {
   const result = await build('foo.js', 'export const result = foo', {
@@ -226,7 +227,7 @@ test('wrapPluginVisitorMethod wraps visitor calls', async () => {
   const result = await build('foo.js', 'export const result = foo', {
     plugins: [identifierReplaceBabelPlugin('foo', true)],
     wrapPluginVisitorMethod(_pluginAlias, _visitorType, callback) {
-      return function (this, p, state) {
+      return function (this: any, p, state) {
         wrapCalled = true
         return callback.call(this, p, state)
       }
@@ -553,7 +554,7 @@ test('babel syntax error produces enhanced error message', async () => {
   const err = await build('foo.js', 'export const = ;', {
     plugins: [identifierReplaceBabelPlugin('foo', true)],
   }).catch((e) => e)
-  const normalized = err.message
+  const normalized = stripVTControlCharacters(err.message)
     .replace(/\r\n/g, '\n')
     .replace(/(?:[A-Z]:)?[\\/][^\s:]+[\\/](?=foo\.js)/gi, '<cwd>/')
     .replace(/\n {4,}at .+/g, '')

packages/babel/src/index.ts

@@ -7,7 +7,7 @@ import {
   resolveOptions,
   type PluginOptions,
 } from './options.ts'
-import * as babel from '@babel/core'
+import * as babel from './babelCompat.ts'
 import type { PartialEnvironment, PresetConversionContext } from './rolldownPreset.ts'
 import { calculatePluginFilters } from './filter.ts'
 import type { ResolvedConfig, Plugin as VitePlugin } from 'vite'

packages/babel/src/options.ts

@@ -1,4 +1,4 @@
-import * as babel from '@babel/core'
+import * as babel from './babelCompat'
 import type { ResolvedConfig } from 'vite'
 import {
   compilePresetFilter,

packages/babel/src/rolldownPreset.test.ts

@@ -11,7 +11,7 @@ import type {
   PresetConversionContext,
   RolldownBabelPreset,
 } from './rolldownPreset.ts'
-import type * as babel from '@babel/core'
+import type * as babel from './babelCompat.ts'
 import type { ResolvedConfig } from 'vite'
 
 const presetA: babel.PresetItem = () => ({ plugins: [] })

packages/babel/src/rolldownPreset.ts

@@ -1,4 +1,4 @@
-import * as babel from '@babel/core'
+import * as babel from './babelCompat.ts'
 import type { GeneralHookFilter, ModuleTypeFilter } from 'rolldown'
 import type { ResolvedConfig, Plugin as VitePlugin } from 'vite'
 import picomatch from 'picomatch'