React Native bundler no longer scans for symlinks in node_modules

[peat-psuwit]

• Review the documentation: https://facebook.github.io/react-native
• Search for existing issues: https://github.com/facebook/react-native/issues
• Use the latest React Native release: https://github.com/facebook/react-native/releases

Environment

  React Native Environment Info:
    System:
      OS: Linux 4.15 Ubuntu 18.04.1 LTS (Bionic Beaver)
      CPU: x64 Intel(R) Core(TM) i7-5500U CPU @ 2.40GHz
      Memory: 116.35 MB / 3.77 GB
      Shell: 4.4.19 - /bin/bash
    Binaries:
      Node: 8.12.0 - /usr/bin/node
      Yarn: 1.10.1 - /usr/bin/yarn
      npm: 6.4.1 - /usr/bin/npm
    SDKs:
      Android SDK:
        Build Tools: 25.0.1, 25.0.2, 25.0.3, 26.0.1, 26.0.2, 27.0.3, 28.0.2, 28.0.3
        API Levels: 23, 25, 26, 27, 28
    npmPackages:
      react: 16.5.0 => 16.5.0 
      react-native: 0.57.2 => 0.57.2 

Description

In React Native 0.56, the bundler will "Scanning folders for symlinks" in the project's node_modules directory. It doesn't do that anymore in React Native 0.57.

Reproduction procedure

1. Clone peat-psuwit/react-native-symlink-scan-demo@9711207, cd linkingProject, and yarn install. At this commit, the version of React Native is 0.56.1.
2. Run react-native start. Notice that in the very first line it said Scanning folders for symlinks in /path/to/linkingProject/node_modules (__ms).
3. Go to http://localhost:8081/index.bundle?platform=android. Notice that it bundles successfully and there's a string "I'm linked!".
4. Now checkout peat-psuwit/react-native-symlink-scan-demo@4298dcc peat-psuwit/react-native-symlink-scan-demo@8e5bb63. Run yarn install again. At this commit, the version of React Native is 0.57.2 0.60.4 and react-native-community/cli is at 2.8.3.
5. Run react-native start. Notice that there isn't Scanning folders for symlinks ... anymore.
6. Go to http://localhost:8081/index.bundle?platform=android. The bundling will fail with Unable to resolve module 'linked-package'.

Additional info

I believe this breaks in 9a77ff5. I'll prepare the PR that fixes this problem.

[gohopo]

I also got this problem
react-native: 0.55.4 => 0.57.3

[stale]

Hey there, it looks like there has been no activity on this issue recently. Has the issue been fixed, or does it still require the community's attention? This issue may be closed if no further activity occurs. You may also label this issue as a "Discussion" or add it to the "Backlog" and I will leave it open. Thank you for your contributions.

[peat-psuwit]

Confirmed that this issue still exists in React Native 0.60.4, with react-native-community/cli 2.8.3. I'll migrate both the issue and the proposed PR to the react-native-community/cli repo.