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Troubleshooting

Linker complains undefined symbols​

e.g. ld: Undefined symbols: std::__1::basic_string ...

Please change the following line in iOS/macos podspec file:

'OTHER_LDFLAGS' => '-force_load ${BUILT_PRODUCTS_DIR}/librust_lib.a',

To something like:

'OTHER_LDFLAGS' => '-force_load ${BUILT_PRODUCTS_DIR}/librust_lib.a -lc++',

Or other libraries that you need (e.g. -framework SystemConfiguration, -framework AudioToolbox, etc).

Please refer to these issues for more details: cargokit#52, bridge#1610.

Another example, which solves the error when using cpal, can be found in #1835.

Issues with glibc (e.g. version GLIBC_2.33 not found)​

As is discussed in this issue and this issue:

This is a https://github.com/canonical/flutter-snap/issues/109 with Flutter Snap not being able to do LTO builds. Just install the Flutter regular way (without snap) and it should work.

Issue with store_dart_post_cobject​

If calling rust function gives the error below, please consider running cargo build again. This can happen when the generated rs file is not included when building is being done.

[ERROR:flutter/lib/ui/ui_dart_state.cc(209)] Unhandled Exception: Invalid argument(s): Failed to lookup symbol 'store_dart_post_cobject': target/debug/libadder.so: undefined symbol: store_dart_post_cobject

Error running cargo ndk: ld: error: unable to find library -lgcc​

Downgrade Android NDK to version 22. This is an ongoing issue with cargo-ndk, a library unrelated to flutter_rust_bridge but solely used to build the examples, when using Android NDK version 23. (See #149)

Fail to run flutter_rust_bridge_codegen on MacOS, "Please supply one or more path/to/llvm..."​

If you are running macOS, you will need to specify a path to your llvm:

flutter_rust_bridge_codegen --rust-input path/to/your/api.rs --dart-output path/to/file/being/bridge_generated.dart --llvm-path /usr/local/homebrew/opt/llvm/

You can install llvm using brew install llvm and it will be installed at /usr/local/homebrew/opt/llvm/ by default.

Freezed file is sometimes not generated when it should be​

If your .freezed.dart or .g.dart seems outdated, ensure you have run the build_runner.

Related: https://github.com/fzyzcjy/flutter_rust_bridge/issues/330

Can't create typedef from non-function type.​

Ensure min sdk version of Flutter pubspec.yaml is at least 2.17.0 to let ffigen happy.

https://github.com/fzyzcjy/flutter_rust_bridge/issues/334

Imported from both bridge_definitions.dart and bridge_generated.io.dart​

If you use a Rust type with Kind in it's name it may conflict with some generated types which can cause a duplicate import error. The workaround is to avoid using Kind as a suffix for a type name in Rust. See issue #757 for more details.

Error on iOS TestFlight only (store_dart_post_cobject)​

You may have an iOS app that works fine in Debug and Release modes locally but when deployed to TestFlight an error occurs trying to locate the store_dart_post_cobject - this is because the nested XCode project for the native bindings maybe be stripping symbols from the linked product.

Select the scheme (eg: Product > Scheme > native-staticlib) and go to Build Settings then under the Deployment section change Strip Linked Product to No; you may also need to change Strip Style to Debugging Symbols.

Generated code is so long​

Indeed all generated code are necessary (if you find something that can be simplified, file an issue). Moreover, other code generation tools also generate long code - for example, when using Google protobuf, a very popular serialization library, I see >10k lines of Java code generated for a quite simple source proto file.

Why need Dart 2.17.0​

Dart SDK >=2.15.0 is supported by this library, but by the latest version of the ffigen tool requires >=2.17.0. Therefore, write sdk: ">=2.17.0 <3.0.0" in the environment section of pubspec.yaml. If you do not want that, consider installing a older version of the ffigen tool.

Why doesn't flutter_rust_bridge_serve work on Firefox?​

This is a known issue stemming from Firefox's stricter rules regarding cross-origin requests. Use Chromium for testing, and check out this guide on enabling crossOriginIsolated for your production servers.

"Could not resolve symbol __cxa_pure_virtual", or libc++_shared issues.​

At the time of writing this, linking with libc++_static or not linking at all may lead to symbol resolution errors when launching the flutter application, after loading your dynamic library. Adding a fix is quite easy, create a build.rs script in the root of your Rust code:

build.rs​

fn main() {
    #[cfg(target_os = "android")]
    println!("cargo:rustc-link-lib=c++_shared");
}

Then, in each jniLibs architecture directory, put the corresponding libc++_shared.so from the Android NDK. libc++_shared.so is typically located in $ANDROID_NDK/toolchains/llvm/prebuilt/. You will have to search for it, as it's different for each operating system.

  • arm-linux-androideabi -> armeabi-v7a
  • aarch64-linux-android -> arm64-v8a
  • i686-linux-android -> x86
  • x86_64-linux-android -> x86_64

Issues on Web?​

Check out Limitations on WASM for some common problems and solutions to adapt existing code to WASM.

Cargokit fails with the SEVERE: error[E0463]: can't find crate for "core" error when building for macos target​

Try to uninstall the rust toolchain and install it again from the scratch:

  1. rustup self uninstall
  2. curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
  3. flutter clean && flutter pub get && flutter run -d macos

Check the related issue on GitHub for the context.

Other problems?​

Don't hesitate to open an issue! I usually reply within minutes or hours (except when sleeping, of course).