[qwertyuiop924]

Yes, I read LTUI and LTUD. But in most languages, function calls and loops don't have the same semantics. I'll call that a different loop primitive.

[eru]

For C, this seems to be implementation defined.

(At least for C as encountered in the wild, I don't know about C the standard.)

Most modern C compilers support tail call optimization.

I don't know about `most languages'. Eg I know Java on the JVM doesn't do tail call optimization. Lots of languages probably do not require TCO of their implementations, though.