Reply To: Grab bag of questions

In the same vein, Wasmtime recently had an RFC for adding tail-calls:

In general, we want Wasmtime to support well-designed, standards-track WebAssembly proposals like the tail calls proposal. The proposal (currently in phase 4) is mature, stable, and implemented in V8 and JSC.

A variety of Wasm producers will and already do target Wasm tail calls. In clang, C++20’s coroutines lower to calls annotated with LLVM’s musttail attribute, which fails to compile to Wasm unless the tail calls proposal is enabled. LLVM’s optimizer will additionally turn regular calls into tail calls when the proposal is enabled. Compiling to Wasm with a continuation passing style where everything is a tail call is a natural fit for some domains, such as lowering a finite state machine to Wasm. Many functional languages guarantee proper tail calls and have to bend over backwards to deliver them without the Wasm tail calls proposal.