Memory leak in `core_utils_rs::trampoline::create_left_trampoline`

[yaokunzhang]

Hello, our detector has flagged what appears to be a soundness issue, potentially leading to undefined behavior

Summary

The create_left_trampoline function in core-utils-rs creates heap-allocated closures via Box::into_raw but provides no mechanism to clean up the allocated memory, leading to guaranteed memory leaks in normal usage.

Reproduction

Minimal example:

use core_utils_rs::trampoline::*;

fn main() {
    let important_data = String::from("this will be freed correctly");
    let (callback, context) = create_left_trampoline(move |_: ()| {
        println!("    Closure logic running. It owns: '{}'", important_data);
    });
}

after excute "cargo miri run"

error: memory leaked: alloc1030 (Rust heap, size: 24, align: 8), allocated here:
  --> .cargo/registry/src/rsproxy.cn-e3de039b2554c837/core-utils-rs-0.3.5/src/trampoline.rs:30:40
   |
30 |         TrampolineRefcon(Box::into_raw(Box::new(wrapped_closure)).cast()),
   |                                        ^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: BACKTRACE:
   = note: inside `core_utils_rs::trampoline::create_left_trampoline::<'_, (), (), {closure@src/main.rs:5:54: 5:66}>` at .cargo/registry/src/rsproxy.cn-e3de039b2554c837/core-utils-rs-0.3.5/src/trampoline.rs:30:40: 30:65
note: inside `main`
  --> src/main.rs:5:31
   |
5  |       let (callback, context) = create_left_trampoline(move |_: ()| {
   |  _______________________________^
6  | |         println!("    Closure logic running. It owns: '{}'", important_data);
7  | |     });
   | |______^

error: memory leaked: alloc882 (Rust heap, size: 28, align: 1), allocated here:
   --> .rustup/toolchains/nightly-2025-05-09-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/alloc/src/raw_vec/mod.rs:476:41
    |
476 |             AllocInit::Uninitialized => alloc.allocate(layout),
    |                                         ^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: BACKTRACE:
    = note: inside `alloc::raw_vec::RawVecInner::try_allocate_in` at .rustup/toolchains/nightly-2025-05-09-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/alloc/src/raw_vec/mod.rs:476:41: 476:63
    = note: inside `<u8 as std::slice::<impl [T]>::to_vec_in::ConvertVec>::to_vec::<std::alloc::Global>` at .rustup/toolchains/nightly-2025-05-09-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/alloc/src/slice.rs:446:29: 446:66
    = note: inside `std::slice::<impl [u8]>::to_vec_in::<std::alloc::Global>` at .rustup/toolchains/nightly-2025-05-09-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/alloc/src/slice.rs:399:16: 399:38
    = note: inside `std::slice::<impl [u8]>::to_vec` at .rustup/toolchains/nightly-2025-05-09-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/alloc/src/slice.rs:375:9: 375:31
    = note: inside `std::slice::<impl std::borrow::ToOwned for [u8]>::to_owned` at .rustup/toolchains/nightly-2025-05-09-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/alloc/src/slice.rs:841:9: 841:22
    = note: inside `std::str::<impl std::borrow::ToOwned for str>::to_owned` at .rustup/toolchains/nightly-2025-05-09-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/alloc/src/str.rs:211:46: 211:72
    = note: inside `<std::string::String as std::convert::From<&str>>::from` at .rustup/toolchains/nightly-2025-05-09-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/alloc/src/string.rs:2974:9: 2974:21
note: inside `main`
   --> src/main.rs:4:26
    |
4   |     let important_data = String::from("this will be freed correctly");
    |                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace

note: set `MIRIFLAGS=-Zmiri-ignore-leaks` to disable this check

error: aborting due to 2 previous errors; 2 warnings emitted