cargo valgrind always reports "leaked 56 B in 1 block"

[Altair-Bueno]

Even Hello world! Is it an issue with valgrind or std::rt?

fn main() {
    println!("Hello, world!");
}

$ cargo valgrind run
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.01s
     Running `/home/abueno@airzonesl.es/.cargo/bin/cargo-valgrind target/debug/test-valgrind`
Hello, world!
       Error leaked 56 B in 1 block
        Info stack trace (user code at the bottom)
             at malloc
             at alloc (alloc.rs:99)
             at alloc_impl (alloc.rs:192)
             at allocate (alloc.rs:254)
             at {closure#0}<std::thread::Inner> (sync.rs:483)
             at allocate_for_layout<core::mem::maybe_uninit::MaybeUninit<std::thread::Inner>, alloc::sync::{impl#14}::new_uninit::{closure_env#0}<std::thread::Inner>, fn(*mut u8) -> *mut alloc::sync::ArcInner<core::mem::maybe_uninit::MaybeUninit<std::thread::Inner>>> (sync.rs:1925)
             at new_uninit<std::thread::Inner> (sync.rs:481)
             at new_inner (mod.rs:1343)
             at new_main (mod.rs:1333)
             at init (rt.rs:113)
             at {closure#0} (rt.rs:172)
             at do_call<std::rt::lang_start_internal::{closure_env#0}, ()> (panicking.rs:557)
             at try<(), std::rt::lang_start_internal::{closure_env#0}> (panicking.rs:520)
             at catch_unwind<std::rt::lang_start_internal::{closure_env#0}, ()> (panic.rs:358)
             at std::rt::lang_start_internal (rt.rs:172)
             at std::rt::lang_start (rt.rs:194)
             at main
     Summary Leaked 56 B total (0 other errors)

$ rustc --version --verbose
rustc 1.83.0 (90b35a623 2024-11-26)
binary: rustc
commit-hash: 90b35a6239c3d8bdabc530a6a0816f7ff89a0aaf
commit-date: 2024-11-26
host: x86_64-unknown-linux-gnu
release: 1.83.0
LLVM version: 19.1.1

$ valgrind --version
valgrind-3.22.0

$ cargo install cargo-valgrind
    Updating crates.io index
     Ignored package `cargo-valgrind v2.2.1` is already installed, use --force to override

test-valgrind.zip

[jfrimmel]

Hello,
thank you for this well-written report. Indeed, this is caused by the Rust 1.83 standard library, as is discussed here: rust-lang/rust#133574. This tool has currently no way to suppress such "leaks" (especially important, since they are intentional), but this has just being requested in #107.

[Altair-Bueno]

Thanks for the quick reply. I imagined it had something to do with that issue, but i thought a reproduction and a clear bug description would be valuable both for contributors and users (who are probably going to panic! when CI fails).