As an optimization my understanding is that GCC and LLVM implement it so Rust, C, and C++ also have it implicitly as optimizations that may or may not apply to your code.
But yes, zig does have a formal language syntax for guaranteeing tail calls to happen at the language level (which I agree with as the right way to expose this optimization).
https://crates.io/crates/tiny_tco
https://crates.io/crates/tco
As an optimization my understanding is that GCC and LLVM implement it so Rust, C, and C++ also have it implicitly as optimizations that may or may not apply to your code.
But yes, zig does have a formal language syntax for guaranteeing tail calls to happen at the language level (which I agree with as the right way to expose this optimization).