fix(module-runner): prevent crash when sourceMappingURL pattern appears in string literals (vitejs#20554)

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: sapphi-red <[email protected]>

Author: Copilot

packages/vite/src/module-runner/evaluatedModules.ts

@@ -108,8 +108,13 @@ export class EvaluatedModules {
     if (!mod) return null
     if (mod.map) return mod.map
     if (!mod.meta || !('code' in mod.meta)) return null
+
+    const pattern = `//# ${SOURCEMAPPING_URL}=data:application/json;base64,`
+    const lastIndex = mod.meta.code.lastIndexOf(pattern)
+    if (lastIndex === -1) return null
+
     const mapString = MODULE_RUNNER_SOURCEMAPPING_REGEXP.exec(
-      mod.meta.code,
+      mod.meta.code.slice(lastIndex),
     )?.[1]
     if (!mapString) return null
     mod.map = new DecodedMap(JSON.parse(decodeBase64(mapString)), mod.file)

packages/vite/src/node/ssr/runtime/__tests__/fixtures/string-literal-sourcemap.ts

@@ -0,0 +1,12 @@
+// This file contains sourceMappingURL pattern in string literals
+// which should not crash the module runner
+
+const text = '//# sourceMappingURL=data:application/json;base64,invalidbase64'
+
+export function getMessage() {
+  return text
+}
+
+export function throwError() {
+  throw new Error('Test error for stacktrace')
+}

packages/vite/src/node/ssr/runtime/__tests__/server-source-maps.spec.ts

@@ -93,4 +93,20 @@ describe('module runner initialization', async () => {
       '    at Module.main (<root>/fixtures/has-error-deep.ts:6:3)',
     ])
   })
+
+  it('should not crash when sourceMappingURL pattern appears in string literals', async ({
+    runner,
+    server,
+  }) => {
+    const mod = await runner.import('/fixtures/string-literal-sourcemap.ts')
+    expect(mod.getMessage()).toBe(
+      '//# sourceMappingURL=data:application/json;base64,invalidbase64',
+    )
+    const error = await getError(() => mod.throwError())
+    expect(error.message).toBe('Test error for stacktrace')
+    expect(serializeStackDeep(server, error).slice(0, 2)).toEqual([
+      'Error: Test error for stacktrace',
+      '    at Module.throwError (<root>/fixtures/string-literal-sourcemap.ts:11:9)',
+    ])
+  })
 })