fix: don't external shim file

closes #351

Author: sxzz

src/features/external.ts

@@ -1,5 +1,6 @@
 import { builtinModules } from 'node:module'
 import Debug from 'debug'
+import { shimFile } from '../index'
 import { toArray } from '../utils/general'
 import type { ResolvedOptions } from '../options'
 import type { PackageJson } from 'pkg-types'
@@ -13,6 +14,7 @@ export function ExternalPlugin(options: ResolvedOptions): Plugin {
     name: 'tsdown:external',
     async resolveId(id, importer, extraOptions) {
       if (extraOptions.isEntry) return
+      if (id === shimFile) return
 
       const { noExternal } = options
       if (typeof noExternal === 'function' && noExternal(id, importer)) {

src/features/shims.ts

@@ -1,13 +1,11 @@
-import path from 'node:path'
-import { pkgRoot } from '../index'
+import { shimFile } from '../index'
 import type { NormalizedFormat, ResolvedOptions } from '../options'
 
 export function getShimsInject(
   format: NormalizedFormat,
   platform: ResolvedOptions['platform'],
 ): Record<string, [string, string]> | undefined {
   if (format === 'es' && platform === 'node') {
-    const shimFile = path.resolve(pkgRoot, 'esm-shims.js')
     return {
       __dirname: [shimFile, '__dirname'],
       __filename: [shimFile, '__filename'],

src/index.ts

@@ -81,7 +81,8 @@ export async function build(userOptions: Options = {}): Promise<void> {
 }
 
 const dirname = path.dirname(fileURLToPath(import.meta.url))
-export const pkgRoot: string = path.resolve(dirname, '..')
+const pkgRoot: string = path.resolve(dirname, '..')
+export const shimFile: string = path.resolve(pkgRoot, 'esm-shims.js')
 
 export type TsdownChunks = Partial<
   Record<NormalizedFormat, Array<OutputChunk | OutputAsset>>