A “bare wasm” target representing a WebAssembly output that makes zero assumptions about its environment.
wasm32-unknown-unknown target is intended to encapsulate use cases
that do not rely on any imported functionality. The binaries generated are
entirely self-contained by default when using the standard library. Although
the standard library is available, most of it returns an error immediately
(e.g. trying to create a TCP stream or something like that).
This target is more or less managed by the Rust and WebAssembly Working Group nowadays at https://github.com/rustwasm.