Why Rust in Android will use the Soong build system, not Cargo

One of the first uses for Rust was rewriting parts of Firefox yet "Cargo was not designed for integration into existing build systems"? That's hard to believe.

Google just don't think it's worth integrating their stuff nicely with pre-existing things :-/

It seems that Google has more build systems that messengers: GN, Bazel, Soong, there were few more but I can not remember them.

A few months ago, Android (AOSP) announced it was moving from Soong to Bazel: <a href="https:&#x2F;&#x2F;blog.bazel.build&#x2F;2020&#x2F;11&#x2F;12&#x2F;aosp_migrating_to_bazel.html" rel="nofollow">https:&#x2F;&#x2F;blog.bazel.build&#x2F;2020&#x2F;11&#x2F;12&#x2F;aosp_migrating_to_bazel....</a><p>Why would Rust in Android move to Soong? Who else is using Soong?