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Alternative NDK setup

This is only needed if you wish to use a version of the Android NDK higher than version 22 with versions of Rust that are lower than version 1.68. This guide details how to prevent the unable to find library -lgcc error.

Android NDK​

Install the latest NDK:

Android Studio > SDK Manager > SDK Tools > NDK (Side by side)

Click on OK at the bottom right corner to start the installation.

cargo-ndk​

You should install cargo-ndk version 2.7.0 or above which works for Android NDK versions greater than 22.

cargo install cargo-ndk --version ^2.7.0

A workaround may be under development in the cargo-ndk project. Until it is finished, you need to manually create four text files to redirect calls from libgcc to libunwind (reference):

  1. Find out all the 4 folders containing file libunwind.a.

    • On Windows, it is similar to:

      C:\Users\Administrator\AppData\Local\Android\Sdk\ndk\24.0.8215888\toolchains\llvm\prebuilt\windows-x86_64\lib64\clang\14.0.1\lib\linux\x86_64\

    • On macOS Monterey, it is similar to:

      ~/Library/Android/sdk/ndk/24.0.8215888/toolchains/llvm/prebuilt/darwin-x86_64/lib64/clang/14.0.1/lib/linux/x86_64/

      The three other folders end with aarch64, arm, i386 instead of x86_64.

  2. Create 4 text files named libgcc.a in the four folders mentioned above with these contents

    INPUT(-lunwind)

More details on NDK with flutter_rust_bridge​

For more details on how NDK works with flutter_rust_bridge, have a look at this article (integrate/android_tasks) please.