fix compilation with new new nightly VaList

In 2025-12-05, a Rust pull request at
rust-lang/rust#141980
reworked the `VaList` implementation to be abi-compatible with C. This
broke:

  * the `printf-compat` implementation, which is fixed in version 0.3
  * some `fcntl` functions, because they called `as_va_list`, and that
    function no longer exists

Here, we fix both of those problems and update the compiler version in
`rust-toolchain.toml` to be the oldest compiler that will already have
this new implementation.

Author: LGFae

c-scape/Cargo.toml

@@ -34,7 +34,7 @@ rand = { version = "0.9.0", default-features = false }
 rustix-dlmalloc = { version = "0.2.1", optional = true }
 rustix-openpty = "0.2.0"
 bitflags = { version = "2.4.1", default-features = false }
-printf-compat = { version = "0.2.1", default-features = false }
+printf-compat = { version = "0.3.0", default-features = false }
 num-complex = { version = "0.4.4", default-features = false, features = ["libm"] }
 posix-regex = { version = "0.1.1", features = ["no_std"] }
 

c-scape/src/fs/fcntl.rs

@@ -9,18 +9,16 @@ use libc::c_int;
 use crate::convert_res;
 
 #[no_mangle]
-unsafe extern "C" fn fcntl(fd: c_int, cmd: c_int, mut args: ...) -> c_int {
-    let args = args.as_va_list();
+unsafe extern "C" fn fcntl(fd: c_int, cmd: c_int, args: ...) -> c_int {
     _fcntl::<libc::flock>(fd, cmd, args)
 }
 
 #[no_mangle]
-unsafe extern "C" fn fcntl64(fd: c_int, cmd: c_int, mut args: ...) -> c_int {
-    let args = args.as_va_list();
+unsafe extern "C" fn fcntl64(fd: c_int, cmd: c_int, args: ...) -> c_int {
     _fcntl::<libc::flock64>(fd, cmd, args)
 }
 
-unsafe fn _fcntl<FlockTy: Flock>(fd: c_int, cmd: c_int, mut args: VaList<'_, '_>) -> c_int {
+unsafe fn _fcntl<FlockTy: Flock>(fd: c_int, cmd: c_int, mut args: VaList<'_>) -> c_int {
     match cmd {
         libc::F_GETFL => {
             libc!(libc::fcntl(fd, libc::F_GETFL));

rust-toolchain.toml

@@ -1,3 +1,3 @@
 [toolchain]
-channel = "nightly-2025-04-28"
+channel = "nightly-2025-12-07"
 components = ["rustc", "cargo", "rust-std", "rust-src", "rustfmt"]