[metro] Metro config option requireCycleIgnorePatterns is not respected

[hdwatts]

Minimal reproducible example

https://github.com/hdwatts/expo-recreation-playground/tree/require-cycle-example

Summary

I use a library that has a cyclical import, which leads to constant log pollution alerting me to refactor the imports.

Metro has support for a requireCycleIgnorePatterns option, which is node_modules by default. Unfortunately, it appears as if that configuration option gets swallowed up by expo somewhere.

In the example repo, I have created a cyclical import and access it on both an Expo Router API route and on the front end. In both cases, my very lenient metro config option is ignored:

config.resolver = {
  ...config.resolver,
  requireCycleIgnorePatterns: [
    /(^|\/|\\)node_modules($|\/|\\)/,
    /.*circular.*/,
  ],
};

Require cycle: components/circular/backend/circle1.ts -> components/circular/backend/circle3.ts -> components/circular/backend/circle2.ts -> components/circular/backend/circle1.ts

Require cycle: components/circular/frontend/circle1.ts -> components/circular/frontend/circle3.ts -> components/circular/frontend/circle2.ts -> components/circular/frontend/circle1.ts

This appears to be web only, and does not occur on iOS.

Environment

expo-env-info 1.2.0 environment info:
System:
OS: macOS 14.2.1
Shell: 5.9 - /bin/zsh
Binaries:
Node: 20.8.1 - ~/Library/Caches/fnm_multishells/4396_1705978127572/bin/node
npm: 10.1.0 - ~/Library/Caches/fnm_multishells/4396_1705978127572/bin/npm
SDKs:
iOS SDK:
Platforms: DriverKit 23.2, iOS 17.2, macOS 14.2, tvOS 17.2, visionOS 1.0, watchOS 10.2
IDEs:
Android Studio: 2022.1 AI-221.6008.13.2211.9619390
Xcode: 15.2/15C500b - /usr/bin/xcodebuild
npmPackages:
expo: ~50.0.2 => 50.0.2
expo-router: ~3.4.3 => 3.4.4
react: 18.2.0 => 18.2.0
react-dom: 18.2.0 => 18.2.0
react-native: 0.73.2 => 0.73.2
react-native-web: ~0.19.6 => 0.19.10
npmGlobalPackages:
eas-cli: 5.7.0
Expo Workflow: managed

[Kudo]

hi there! i tried your repro but it doesn't show the require cycle error for me.

$ git clone https://github.com/hdwatts/expo-recreation-playground.git
$ cd expo-recreation-playground
$ git checkout require-cycle-example
$ bun i --frozen-lockfile
$ npx expo start -i

after removing the line, the error starts to appear. do i miss anything from the repro?

[hdwatts]

Do i miss anything from the repro?

Good call out - my repro was using web not iOS. I've updated my issue to reflect that.

I can confirm that on iOS the logs do not appear, but on web they do.

[Kudo]

i can confirm the issue and accept the issue. also, let us keep it as lower priority. the error seems to be coming from the api-routes server renderer that we keep working.

[expo-bot]

Thank you for filing this issue!
This comment acknowledges we believe this may be a bug and there’s enough information to investigate it.
However, we can’t promise any sort of timeline for resolution. We prioritize issues based on severity, breadth of impact, and alignment with our roadmap. If you’d like to help move it more quickly, you can continue to investigate it more deeply and/or you can open a pull request that fixes the cause.

[javascripter]

I'm using the below pathc-package patch for now.

diff --git a/node_modules/metro-runtime/src/polyfills/require.js b/node_modules/metro-runtime/src/polyfills/require.js
index ce67cb4..18edd64 100644
--- a/node_modules/metro-runtime/src/polyfills/require.js
+++ b/node_modules/metro-runtime/src/polyfills/require.js
@@ -131,7 +131,9 @@ function metroRequire(moduleId) {
 // `requireCycleIgnorePatterns` configuration.
 function shouldPrintRequireCycle(modules) {
   const regExps =
-    global[__METRO_GLOBAL_PREFIX__ + "__requireCycleIgnorePatterns"];
+    global[__METRO_GLOBAL_PREFIX__ + "__requireCycleIgnorePatterns"] ||
+    // HACK: Expo SSR mode doesn't have this global. Fall back to the default.
+    [/(^|\/|\\)node_modules($|\/|\\)/];
   if (!Array.isArray(regExps)) {
     return true;
   }

In this function,

function shouldPrintRequireCycle(modules) {
  const regExps =
    global[__METRO_GLOBAL_PREFIX__ + "__requireCycleIgnorePatterns"]

the value does not exist in the global object or globalThis object. If you eval it like this there, the value exists, so I guess prelude code is injected in a wrong place/environment or something.

eval(__METRO_GLOBAL_PREFIX__ + "__requireCycleIgnorePatterns"])

[bryanltobing]

can confirm that this is still the issue when using api-routes. solving with patch for now

[SleeplessByte]

This is an issue when not using api-routes, but regular expo-router on web.

Workaround by #26613 (comment) works.