F & Q

Why is the binary's size larger than C++ ?

In fact, Rust's build products are generally about 10 times larger than C++'s build products. However, as the code functionality increases, this gap will gradually narrow. You can refer to min-sized-rust for optimization.

Option<T> will cause a crash

For optional parameters, they will be assigned to undefined in Node.js, but HarmonyOS lacks this step, which will cause the framework to fail to confirm the parameters and thus cause a crash.

This error is related to the phone's ROM. At this stage, you should avoid using optional parameters.

How to migrate existing .so files from Android and iOS ?

In fact, we cannot directly use any previously compiled .so files from non-HarmonyOS platforms.

All .so files must be recompiled with HarmonyOS's NDK to meet the specifications, otherwise they cannot be used.

A real example is compiling openssl for HarmonyOS. You can find the example.