RN64 Hermes iOS: No console.logs anymore: "JavaScript logs will appear in your environment console"

[mrousavy]

Since I upgraded from RN 0.63 to RN 0.64 (rc3) and enabled Hermes I cannot see my console.logs anymore.

The same thing in Flipper Logs.

• iOS with Hermes: no logs ❌
• iOS with JSC: logs ✅
• Android with Hermes: logs ✅
• Android with JSC: logs ✅

Out put of npx react-native --version:

5.0.1-alpha.1

Probably related

• https://github.com/facebook/flipper/issues/1913
• https://github.com/react-native-community/releases/issues/214#issuecomment-775899526

[alloy]

@mrousavy I have no clear ideas offhand, but would suggest you start debugging from here, which is where the logs come out of the engine.

[mrousavy]

@alloy I've tried tracking it down like this:

• setUpDeveloperTools.js:L68-L77 notices that console._isPolyfilled is false, so it logs that "warning" to my console (which obviously works, no idea why it doesn't just use it then?)
• console.js:L546 checks if the native console hook is available, and only then prepares the console polyfill
• JSIExecutor.cpp:L515 binds the native console hook that we required in the step above, but somehow this fails so everything else also fails to polyfill.

I'm thinking if this maybe has something to do with Reanimated, since that also creates a separate Runtime instance - maybe there are conflicts introduced by this?

[mrousavy]

Okay the code I linked doesn't even get called. It should get called with RCTJSIExecutorRuntimeInstaller, but in RCTCxxBridge.mm it enters this if, causing the installer to get skipped.

I believe this has something to do with how react-native-navigation sets up the bridge (see https://github.com/wix/react-native-navigation/pull/6835), still investigating.. 🕵️

[mrousavy]

Resolved! It was a reanimated issue. See: https://github.com/software-mansion/react-native-reanimated/pull/1704

[alloy]

Ah I see, good sleuthing :clap:

[KingAmo]

still have this problem with react-native-reanimated v2.0.0, hermes enabled in iOS