The request asks for toolchains to cross-compile and cross-test Rust. The most relevant source here is cargo-nextest 6, a next-generation Rust test runner that can filter tests by platform, which supports cross testing, and Ninja 5, a build system that lists cross-compilation among its indexed topics. Setting up actual cross-compilation targets is not documented in the sources provided, so the answer is only partial.

A question back: Which target platforms (for example, Linux on ARM, Windows, or WebAssembly) do you want to cross-compile to, and from which host?

1. 1

   cargo-nextestnexte.stwebsite read, tools not yet checked

   A test runner for Rust that lets you select tests by name, binary, or platform, useful for running tests in cross-testing setups 6.

   WebsiteDocs

2. 2

   Ninjaninja-build.orgverified and signed

   A small build system focused on speed that is indexed for cross-compilation and cross-platform builds, as a lower-level build backend 5.

   Website

   for agents: cross-compilation · cross-platform · c++

3. 3

   Instainsta.rsverified and signed

   A snapshot testing tool for Rust that can be used alongside cargo test workflows to compare outputs across builds 3.

   WebsiteDocs

   +8 community tools built for it

   for agents: ghidra · execute · pexpect_tool