Comment by ckcheng

TCO is surprisingly commonly supported in the real world. TCO is supported in C++ compilers, JavaScript in Safari, Scala, Clojure in a way, etc.!

For instance:

"All current mainstream [C++] compilers perform tail call optimisation fairly well (and have done for more than a decade), even for mutually recursive calls" [1].

"As of July 22, 2023 Safari is the only browser that supports tail call optimization" of JavaScript [2].

"Since Clojure uses the Java calling conventions, it cannot, and does not, make the same tail call optimization guarantees. Instead, it provides the recur special operator, which does constant-space recursive looping" [3].

"The Scala compiler will automatically optimize any truly tail-recursive method. If you annotate a method that you believe is tail-recursive with the @tailrec annotation, then the compiler will warn you if the method is actually not tail-recursive" [4].

[1]: https://stackoverflow.com/a/34129

[2]: https://stackoverflow.com/a/37224563

[3]: https://stackoverflow.com/a/34097339

[4]: https://stackoverflow.com/a/3114245