react-native: E/libc++abi: terminating with uncaught exception of type std::bad_cast: std::bad_cast

Description

As of version 0.62.0, there’s a conflict in libc++_shared.so between react-native and tesseract. This issue can be observed with any version of ScanbotSDK, however, it only shows up as of 0.62.0 react-native version.

I already faced SDK linking issues with this version of react-native when I first tried it out. Then found that an additional required step is now adding the following to settings.gradle:

include ':react-native-scanbot-sdk'
project(':react-native-scanbot-sdk').projectDir =
        new File(rootProject.projectDir, '../node_modules/react-native-scanbot-sdk/android/app')

But, as I am posting this, it’s still not enough. Workaround and details below.

React Native version:

System:
    OS: macOS 10.15.6
    CPU: (16) x64 Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz
    Memory: 3.03 GB / 32.00 GB
    Shell: 5.7.1 - /bin/zsh
  Binaries:
    Node: 12.13.0 - ~/.nvm/versions/node/v12.13.0/bin/node
    npm: 6.12.0 - ~/.nvm/versions/node/v12.13.0/bin/npm
    Watchman: 4.9.0 - /usr/local/bin/watchman
  SDKs:
    iOS SDK:
      Platforms: iOS 13.5, DriverKit 19.0, macOS 10.15, tvOS 13.4, watchOS 6.2
    Android SDK:
      API Levels: 26, 28, 29
      Build Tools: 27.0.3, 28.0.3, 29.0.2, 29.0.3
      System Images: android-28 | Google Play Intel x86 Atom
      Android NDK: 21.0.6113669
  IDEs:
    Android Studio: 4.0 AI-193.6911.18.40.6514223
    Xcode: 11.5/11E608c - /usr/bin/xcodebuild
  npmPackages:
    react: 16.11.0 => 16.11.0 
    react-native: 0.62.2 => 0.62.2 
  npmGlobalPackages:
    react-native: 0.61.4

Steps To Reproduce

1. Clone https://github.com/doo/scanbot-sdk-example-react-native/tree/v4.1.0
2. Change "react-native-scanbot-sdk": "4.1.0-rc2", back to "react-native-scanbot-sdk": "4.1.0-beta10",
3. react-native run-android
4. Press Scan MRZ on ID Card
5. E/libc++abi: terminating with uncaught exception of type std::bad_cast: std::bad_cast

The same can be reproduced with a hello-world app created via npx react-native init AwesomeProject

Expected Results

Well, I’d expect the MRZ Scanner to start. As you can observe when you change "react-native-scanbot-sdk" back to "4.1.0-rc2", where I’ve implemented the workaround.

Or you can change "react-native" to anything below "0.62", and it will run as expected.

Snack, code example, screenshot, or link to a repository:

Instead of snacking, I’ll explain the process and workaround that I found.

First, the issue. When compiling our core with debug symbols attached, I can see that the bad_cast is, in fact, inside tesseract. In a relatively harmless piece of code, nonetheless:

const char* buffer = "NULL 0 NULL 0\n";
std::istringstream stream(buffer);
stream.imbue(std::locale::classic());
// 标 1 0,255,0,255,0,0,0,0,0,0 Han 68 0 68 标  # 标 [6807 ]x
stream >> std::setw(255) >> unichar >> std::hex >> properties >> std::dec;

If I move that same block back into our core, it passes through it with a breeze… but inside tesseract it crashes with the bad_cast exception inside c++ shared library. It cannot find a facet, that should be there in every case.

Well, at this point I was pretty dumbfounded, and cannot debug shared library without debug symbols and with optimizations.

Off to my next adventure: Building the standard library in debug mode. But of course, that cannot be done separately, so I had to download all of Google’s monorepo (60gb, woo) and compile the entirety android NDK from source in debug, so I could see what the hell was going on in locale.cpp.

That step was a bit easier than I thought. Just sprinkled some of the following around in different makefiles:

LOCAL_CFLAGS += -O0 -UNDEBUG -g
LOCAL_CPPFLAGS += -O0 -UNDEBUG -g

Now I have the debug build of libc++_shared.so, weighing just shy of 6mb (a bit less than 1mb in release), that I copied to my NDK directory: /Users/$USER/Library/Android/sdk/ndk/19.2.5345600/sources/cxx-stl/llvm-libc++/libs/arm64-v8a

I specifically used the same NDK react-native is compiled with, as described here. And I also built react-native from source, just so I could control every aspect of it and specify which NDK to use in all cases…

And it works. No more crash. Cannot reproduce the issue with the debug build of libc++_shared.so. Well, what now?

So I included the debug build in our SDK and wrote a simple "postinstall" script that copies the binary to project/app/src/main/jniLibs and now the correct c++ standard library is included in the apk.

As you can see, that’s still a… well, relatively dirty workaround. Still not sure what exactly changed in react-native builds between versions 0.61 and 0.62 on that level. Anyone?

Thank you for coming to my TED talk