Use metro-bundler from master

At Facebook we use both react-native and metro-bundler from master. The open source version of react-native depends on a concrete version of metro from npm. We often break react-native when we change the module boundaries in a single diff for both repos internally at Facebook, and this is not ideal as it breaks the react-native repo and requires us to bump a Metro version.

Instead, I propose to:

• Change react-native to depend on github’s version of Metro from master
• Compile Metro using babel-register and link it into node_modules/metro-bundler
• When making an RN release, publish a new version of Metro and lock that version into package.json

It’s possible that we still break react-native master if the two repos diverge or the sync script for metro-bundler is delayed, but that shouldn’t happen often and is the cause of another issue that can be fixed (or will fix itself with time). I think this will lead to fewer breakages from us and allow everyone to move faster 😃

@brentvatne @grabbou know anyone who could work on this?

[cpojer]

@nihgwu this is not the right issue to discuss that. In the future there may be a way for you to pick any version of Metro together with React Native. In the meantime, you can use the selective versions resolution feature we built into Yarn and outlined in the 1.0 blogpost: https://code.facebook.com/posts/274518539716230/announcing-yarn-1-0/

[nihgwu]

sorry to break the topic, I’m using RN0.49RC with metro-bundler@^0.13.0, and I can’t start my app because I’m using moment, and it always breaks here, but I don’t get that error with previous RN versions, so I believe that’s a issue from metro-bundler, but as RN has a lock version of it, unless we cherry-pick the right version with the patch, it will always break, I have to comment out that line every time I run yarn add