`c_variadic` feature will be stable in Rust 1.93

[polarathene]

This issue is just to inform the maintainer(s) about stabilization of the previously nightly-only unstable feature:

printf-compat/src/lib.rs

Lines 3 to 4 in b1f0c7c

	//! This is a complete reimplementation of `printf` in Rust, using the unstable
	//! (i.e. **requires a Nightly compiler**) `c_variadic` feature.

• Was stabilized in Nightly in Nov 2025
• Will become stable in Rust from 1.93 onwards

---

When adapting to this change, be sure to also add rust-version = "1.93" to Cargo.toml as a way to communicate to Cargo that the MSRV is 1.93 due to that requirement (which can also be used for MSRV-based dep resolution by projects).

[nicholasbishop]

I think that's a different thing being stabilized. As described in the 1.93 release notes, the change is "Stabilize declaration of c-style variadic functions for the system ABI".

The feature we require, c_variadic, is tracked here: rust-lang/rust#44930

It is being worked on, but isn't stable just yet.

[polarathene]

core::ffi::va_list::{VaArgSafe, VaList} is now stabilized for the eventual Rust 1.99 (Oct 2026) release 👍

Will this remove the need for nightly going forward?

[nicholasbishop]

Yep, soon :)