OK, if you prefer to be precise, there are two situations: (1) In languages (or runtimes) where tail calls are not guaranteed to be elided, tail call elision i

OK, if you prefer to be precise, there are two situations: (1) In languages (or runtimes) where tail calls are not guaranteed to be elided, tail call elision is an optimisation. In that context, you could quite reasonably describe it as tail call optimisation. Programs that are written in these languages and rely on tail call elision are buggy. (2) In languages (or runtimes) where tail calls are guaranteed to be elided, tail call elision is not an optimisation. In that context, you cannot reasonably describe it as tail call optimisation. Programs that are written in these languages and rely on tail call elision are not buggy (at least, not for that reason!). This conversation is about making tail call elision a guaranteed feature of WASM. Therefore, in this context, it is not reasonable to describe tail call elision as an optimisation.