AFAIK guaranteed TCE wasn't supported in LLVM at all when Rust was still being designed and considered adding it. Support for musttail in LLVM has been added re

AFAIK guaranteed TCE wasn't supported in LLVM at all when Rust was still being designed and considered adding it. Support for musttail in LLVM has been added relatively recently. WASM doesn't support guaranteed TCE yet (it's a proposal), and that's an important target for Rust. https://github.com/rust-lang/rfcs/issues/2691 https://github.com/rust-lang/rfcs/issues/2691