std build broken for uclibc

[xtqqczze]

$ cargo new hello_world
$ cd hello_world
$ cargo +nightly --version
cargo 1.96.0-nightly (888f67534 2026-03-30)
$ cargo +nightly check -Zbuild-std --target armv7-unknown-linux-uclibceabihf

   Compiling std v0.0.0 (~/.rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/src/rust/library/std)
error[E0425]: cannot find value `AT_MINSIGSTKSZ` in crate `libc`
   --> ~/.rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/src/rust/library/std/src/sys/pal/unix/stack_overflow.rs:310:63
    |
310 | ...fe { libc::getauxval(libc::AT_MINSIGSTKSZ) };
    |                               ^^^^^^^^^^^^^^
    |
   ::: ~/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/libc-0.2.183/src/unix/linux_like/linux/uclibc/mod.rs:400:1
    |
400 | pub const MINSIGSTKSZ: c_int = 2048;
    | ---------------------------- similarly named constant `MINSIGSTKSZ` defined here
    |
help: a constant with a similar name exists
    |
310 -         let dynamic_sigstksz = unsafe { libc::getauxval(libc::AT_MINSIGSTKSZ) };
310 +         let dynamic_sigstksz = unsafe { libc::getauxval(libc::MINSIGSTKSZ) };
    |

For more information about this error, try `rustc --explain E0425`.
error: could not compile `std` (lib) due to 1 previous error

cc: @skrap

[xtqqczze]

@asomers Likely commit 470facc (Update libc to v0.2.183)

[asomers]

This is a regression in the libc crate, introduced sometime between 0.2.178 and 0.2.180 . You should open a ticket there. CC @skrap as target maintainer for this platform.

[tgross35]

Libc was fixed for uclibc, there is no AT_MINSIGSTKSZ defined on uclibc. A PR to std will be needed.to update, Cc mantainers of uclibc targets, @lancethepants @farao.

The MINSIGSTKSZ const that it suggests doesn't seem to be anywhere either https://github.com/search?q=repo%3Akraj%2FuClibc+MINSIGSTKSZ.&type=code.

(Note that all uclibc targets are tier 3 so occasional breakage like this is expected.)

[xtqqczze]

The MINSIGSTKSZ const that it suggests doesn't seem to be anywhere either

https://github.com/kraj/uClibc/blob/ca1c74d67dd115d059a875150e10b8560a9c35a8/libc/sysdeps/linux/common/bits/sigstack.h#L44

[tgross35]

Yup I stand corrected, noted in the thread at rust-lang/libc#5039 too. Libc PRs to fix this accepted in this case, assuming it's been tested against an actual uclibc system.