duplicate lang item `panic_impl'

What happened?

Compiling a simple guest example fails with:

error[E0152]: found duplicate lang item `panic_impl`
   --> /home/sarocu/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/hyperlight-guest-bin-0.12.0/src/lib.rs:139:1
    |
139 | / fn panic(info: &core::panic::PanicInfo) -> ! {
140 | |     _panic_handler(info)
141 | | }
    | |_^
    |
    = note: the lang item is first defined in crate `std` (which `tracing` depends on)
    = note: first definition in `std` loaded from /home/sarocu/.rustup/toolchains/1.89-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libstd-099ea48a26be4ce8.rlib
    = note: second definition in the local crate (`hyperlight_guest_bin`)

Dependencies:

[dependencies]
hyperlight-common = "0.12.0"
hyperlight-guest = "0.12.0"
hyperlight-guest-bin = "0.12.0"
hyperlight-guest-tracing = "0.12.0"

Rust:

cargo --version
cargo 1.89.0 (c24e10642 2025-06-23)

What did you expect to happen?

Successful build

Steps to reproduce the behavior

Install the shared dependencies in a new project
Copy the example snippet for a guest hyperlight binary in the README
cargo build

Hyperlight Version

0.12.0

OS version

             /////////////                
         /////////////////////            -------------
      ///////*767////////////////         OS: Pop!_OS 24.04 LTS x86_64
    //////7676767676*//////////////       Kernel: 6.17.9-76061709-generic
   /////76767//7676767//////////////      Uptime: 3 hours, 32 mins
  /////767676///*76767///////////////     Packages: 2082 (dpkg), 13 (flatpak)
 ///////767676///76767.///7676*///////    Shell: bash 5.2.21
/////////767676//76767///767676////////   Resolution: 3440x1440
//////////76767676767////76767/////////   DE: COSMIC
///////////76767676//////7676//////////   Theme: adw-gtk3 [GTK3]
////////////,7676,///////767///////////   Icons: Cosmic [GTK3]
/////////////*7676///////76////////////   Terminal: cosmic-term
///////////////7676////////////////////   CPU: AMD Ryzen 7 3700X (16) @ 3.800GHz
 ///////////////7676///767////////////    GPU: NVIDIA 09:00.0 NVIDIA Corporation Device 2d04
  //////////////////////'////////////     Memory: 8201MiB / 31999MiB
   //////.7676767676767676767,//////
    /////767676767676767676767/////
      ///////////////////////////
         /////////////////////
             /////////////

Additional Information

No response

Hello and thanks for the report! Would you mind speciying exactly how you compiled the guest? We mostly use cargo-hyperlight to build guests which automatically sets up certain things. Have you tried cargo hyperlight build instead, which I also think is what our README uses?

What does your guest look like? you will need to have: (see https://github.com/hyperlight-dev/hyperlight?tab=readme-ov-file#guest)

#![no_std]
#![no_main]
extern crate alloc;

There are some additional settings required to build and link everything properly. The easiest way to get it built is:

cargo install --locked cargo-hyperlight
cargo hyperlight build

if your still having trouble, if you could provider a minimal example and the command you ran that would help

@jsturtevant

@jsturtevant I attempted to build with that exact file. I am using the published crates in a fresh project rather than cloning the repo so maybe I am just misunderstanding something with the architecture.

Seems to be a dependency issue; @ludfjig when I use that build command I see a lot of errors that are related to building deps:

error: could not compile `serde_core` (lib) due to 5866 previous errors

thread 'main' panicked at /home/sarocu/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/cargo-hyperlight-0.1.5/src/main.rs:28:10:
Failed to execute cargo: Failed to execute cargo

Caused by:
    Command exited with code 101:
    AR_x86_64-hyperlight-none="/usr/bin/ar" BINDGEN_EXTRA_CLANG_ARGS="--target=x86_64-unknown-linux-none -U__linux__ -fPIC -fno-stack-protector -fstack-clash-protection -mstack-probe-size=4096 -mno-red-zone -nostdinc -DHYPERLIGHT=1 -D__HYPERLIGHT__=1  -isystem /home/sarocu/Projects/heyvm/guest/target/sysroot/lib/rustlib/x86_64-hyperlight-none/include --target=x86_64-unknown-linux-none -U__linux__ -fPIC -fno-stack-protector -fstack-clash-protection -mstack-probe-size=4096 -mno-red-zone -nostdinc -DHYPERLIGHT=1 -D__HYPERLIGHT__=1  -isystem /home/sarocu/Projects/heyvm/guest/target/sysroot/lib/rustlib/x86_64-hyperlight-none/include" CARGO_BUILD_TARGET="x86_64-hyperlight-none" CC_x86_64-hyperlight-none="/usr/bin/clang" CFLAGS_x86_64-hyperlight-none="--target=x86_64-unknown-linux-none -U__linux__ -fPIC -fno-stack-protector -fstack-clash-protection -mstack-probe-size=4096 -mno-red-zone -nostdinc -DHYPERLIGHT=1 -D__HYPERLIGHT__=1  -isystem /home/sarocu/Projects/heyvm/guest/target/sysroot/lib/rustlib/x86_64-hyperlight-none/include" CLANG_PATH="/usr/bin/clang" RUSTFLAGS="--sysroot /home/sarocu/Projects/heyvm/guest/target/sysroot --cfg=hyperlight --check-cfg=cfg(hyperlight) -Clink-args=-eentrypoint" RUSTUP_TOOLCHAIN="1.89-x86_64-unknown-linux-gnu" "/home/sarocu/.rustup/toolchains/1.89-x86_64-unknown-linux-gnu/bin/cargo" "build"

note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Are you able to build the guest checked into this repo with the command using command just guests in root folder? The issue could also potentially be because one of

[dependencies]
hyperlight-common = "0.12.0"
hyperlight-guest = "0.12.0"
hyperlight-guest-bin = "0.12.0"
hyperlight-guest-tracing = "0.12.0"

pulls in std. Can you try adding default-features = false on these (at least hyperlight-common).

@ludfjig

@ludfjig building inside of this repo works with the just guests command

Added default-features = false and tried the 0.11.0 release as well and still see errors

@ludfjig building inside of this repo works with the just guests command

Added default-features = false and tried the 0.11.0 release as well and still see errors

Thanks for checking. I tried it myself and managed to make the following work. It's harder than I thought, and the error messages were pretty cryptic. In addition I needed to do a full cargo clean to get it to work.

main.rs:

#![no_std]
#![no_main]

extern crate alloc;
extern crate hyperlight_guest_bin;

#[unsafe(no_mangle)]
pub extern "C" fn hyperlight_main() {
    unimplemented!()
}

#[unsafe(no_mangle)]
pub fn guest_dispatch_function(
    _function_call: hyperlight_common::flatbuffer_wrappers::function_call::FunctionCall,
) -> hyperlight_guest::error::Result<alloc::vec::Vec<u8>> {
    unimplemented!()
}

Cargo.toml

[package]
name = "test_guest"
version = "0.1.0"
edition = "2024"

[dependencies]
hyperlight-guest = { version = "0.12.0" }
hyperlight-guest-bin = { version = "0.12.0"}
hyperlight-common = { version = "0.12.0", default-features = false }

Please let me know if the above works for you! We have been thinking about making some tool to scaffold a new guest, and I think that definitely would be useful and potentially avoid problems like these

That works!

Some sort of tool would be great, maybe a quick edit on the README. Appreciate the assist!

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duplicate lang item `panic_impl' #1175

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duplicate lang item `panic_impl' #1175

Description

What happened?

What did you expect to happen?

Steps to reproduce the behavior

Hyperlight Version

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Additional Information

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ludfjig commented on Jan 17, 2026

jsturtevant commented on Jan 17, 2026

sarocu commented on Jan 20, 2026

ludfjig commented on Jan 20, 2026

sarocu commented on Jan 21, 2026

ludfjig commented on Jan 22, 2026

sarocu commented on Jan 22, 2026

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