fix(config): handle shebang properly (#21158)

Author: sapphi-red

packages/vite/src/node/__tests__/config.spec.ts

@@ -854,6 +854,17 @@ describe('loadConfigFromFile', () => {
     expect(c.resolved).toBe(c.url)
   })
 
+  test('shebang is preserved at the top of the file', async () => {
+    const { config } = (await loadConfigFromFile(
+      {} as any,
+      path.resolve(fixtures, './shebang/vite.config.ts'),
+      path.resolve(fixtures, './shebang'),
+    ))!
+
+    const c = config as any
+    expect(c.dirname).toContain('shebang')
+  })
+
   describe('loadConfigFromFile with configLoader: native', () => {
     const fixtureRoot = path.resolve(fixtures, './native-import')
 

packages/vite/src/node/__tests__/fixtures/config/shebang/vite.config.ts

@@ -0,0 +1,4 @@
+#!/usr/bin/env node
+export default {
+  dirname: import.meta.dirname,
+}

packages/vite/src/node/config.ts

@@ -2044,9 +2044,22 @@ async function bundleConfigFile(
               }
             }
 
+            let injectedContents: string
+            if (contents.startsWith('#!')) {
+              // hashbang
+              let firstLineEndIndex = contents.indexOf('\n')
+              if (firstLineEndIndex < 0) firstLineEndIndex = contents.length
+              injectedContents =
+                contents.slice(0, firstLineEndIndex + 1) +
+                injectValues +
+                contents.slice(firstLineEndIndex + 1)
+            } else {
+              injectedContents = injectValues + contents
+            }
+
             return {
               loader: args.path.endsWith('ts') ? 'ts' : 'js',
-              contents: injectValues + contents,
+              contents: injectedContents,
             }
           })
         },