dynamic librustc_driver path is not set by charon #588

zjp-CN · 2025-03-10T13:18:05Z

Personally speaking, the dynamic linked librustc_driver path should be always set before calling charon, otherwise there will be a loading problem.

I didn't find any issue reporting this. So this is a record for anyone who comes across the problem the first time.

On Linux, LD_LIBRARY_PATH should be set to the specified toolchain lib path:

# Ignore the inconsistent toolchains on Linux and Windows
$ rustup default nightly-2024-08-11
info: using existing install for 'nightly-2024-08-11-x86_64-unknown-linux-gnu'
info: default toolchain set to 'nightly-2024-08-11-x86_64-unknown-linux-gnu'

  nightly-2024-08-11-x86_64-unknown-linux-gnu unchanged - rustc 1.82.0-nightly (730d5d409 2024-08-10)


$ charon-driver rustc -vV
charon-driver: error while loading shared libraries: librustc_driver-9694e87df53074e6.so: cannot open shared object file: No such file or directory

$ export LD_LIBRARY_PATH=/root/.rustup/toolchains/nightly-2024-08-11-x86_64-unknown-linux-gnu/lib

$ charon-driver rustc -vV
rustc 1.82.0-nightly (730d5d409 2024-08-10)
binary: rustc
commit-hash: 730d5d4095a264ef5f7c0a0781eea68c15431d45
commit-date: 2024-08-10
host: x86_64-unknown-linux-gnu
release: 1.82.0-nightly
LLVM version: 19.1.0

On Windows, you'll get a windows popup saying dll is not found or something, or get a painic error from CLI indicating stdout and stderr are empty strings:

charon\charon $ target\debug\charon --print-llbc --input tests\ui\arrays.rs --no-cargo
The required toolchain is not installed. Installing...
info: syncing channel updates for 'nightly-2024-10-23-x86_64-pc-windows-msvc'

  nightly-2024-10-23-x86_64-pc-windows-msvc unchanged - rustc 1.84.0-nightly (86d69c705 2024-10-22)

thread 'main' panicked at src/bin/charon/main.rs:174:13:
info: checking for self-update
info: component 'rustc-dev' for target 'x86_64-pc-windows-msvc' is up to date
info: component 'llvm-tools' for target 'x86_64-pc-windows-msvc' is up to date
thread 'main' panicked at src/bin/charon/main.rs:174:13:
failed to determine underlying rustc version of Charon:
CommandError { stdout: "", stderr: "" }

So the solution is adding the toolchain path, e.g. C:\Users\Administrator\.rustup\toolchains\nightly-2024-10-23-x86_64-pc-windows-msvc\lib\rustlib\x86_64-pc-windows-msvc\lib, to system environment variable PATH, and restart the terminal to make it work.

The text was updated successfully, but these errors were encountered:

Nadrieril · 2025-03-10T15:33:55Z

This is a bug that should be fixed. On Linux and Mac, charon does always set up the toolchain path before calling the driver. You should never have to set it up yourself. Could you tell me how to set it up on Windows?

Nadrieril · 2025-03-10T15:36:42Z

I use rustup run <toolchain> charon-driver which should normally add the right paths. If that's not working I don't know how to do it properly. Can you check if rustup run nightly-2024-10-23 path\to\charon-driver works on windows?

Nadrieril · 2025-03-10T15:57:30Z

Also, have you encountered this bug on Linux? I would like to know what your setup is because that's also a bug that should be fixed.

zjp-CN · 2025-03-11T01:35:18Z

Based on the de91049 , I still got the dll loading error with rustup run nightly-2024-10-23 charon-driver on Windows

Sorry, it's Chinese; it basically says rustc_driver dll is not found. The solution I can confirm is

adding the toolchain path, e.g. C:\Users\Administrator\.rustup\toolchains\nightly-2024-10-23-x86_64-pc-windows-msvc\lib\rustlib\x86_64-pc-windows-msvc\lib, to system environment variable PATH, and restarting the terminal to make it work.

On Linux and Mac, charon does always set up the toolchain path before calling the driver. You should never have to set it up yourself.

Oh, it works on Linux! I mean

rustup run nightly-2024-10-23 target/debug/charon-driver rustc -vV prints stuff correctly
target/debug/charon --no-cargo --input tests/ui/arrays.rs --print-ullbc --rustc-flag=--crate-type=rlib prints stuff correctly

I didn't realize rustup run sets up toolchain path. So there's no problem on Linux now.

zjp-CN · 2025-03-11T01:50:46Z

It's weird. rustup run nightly-2024-10-23 rustc -vV works fine on Windows:

$ rustup run nightly-2024-10-23 rustc -vV
rustc 1.84.0-nightly (86d69c705 2024-10-22)
binary: rustc
commit-hash: 86d69c705a552236a622eee3fdea94bf13c5f102
commit-date: 2024-10-22
host: x86_64-pc-windows-msvc
release: 1.84.0-nightly
LLVM version: 19.1.1

But rustup run nightly-2024-10-23 target\debug\charon-driver.exe rustc -vV doesn't. Maybe this is a rustup bug? (Yes :)

Update: I think there is a bug from ~~charon-driver~~ rustup. On Windows, I made a test for rustup:

fn main() {
    let args: Vec<_> = std::env::args().collect();
    dbg!(&args);
    let output = std::process::Command::new("rustc")
        .args(args)
        .output()
        .unwrap();
    let stdout = std::str::from_utf8(&output.stdout).unwrap();
    let stderr = std::str::from_utf8(&output.stderr).unwrap();
    println!("stdout = {stdout}\ntderr = {stderr}");
}

rustup run succeeds in forwarding -vV to rustc

$ rustup run nightly-2024-10-23 target\debug\test-rustup.exe -vV
[src\main.rs:3:5] &args = [
    "target\\debug\\test-rustup.exe",
    "-vV",
]
stdout = rustc 1.84.0-nightly (86d69c705 2024-10-22)
binary: rustc
commit-hash: 86d69c705a552236a622eee3fdea94bf13c5f102
commit-date: 2024-10-22
host: x86_64-pc-windows-msvc
release: 1.84.0-nightly
LLVM version: 19.1.1

tderr =

Nadrieril · 2025-03-11T12:23:22Z

So far this is consistent with my understanding: the issue is that charon-driver.exe dynamically links to rustc_driver.dll. rustc itself doesn't need that, which is why it runs correctly.

It seems that rustup run correctly sets up binary discovery (so rustc is found), but not dll discovery. I don't think there's anything that charon-driver.exe can do because this dynamic linking is done by the OS when we ask to run charon_driver.exe.

It seems that rustup doesn't even try to set up the right loader paths on windows: https://github.com/rust-lang/rustup/blob/895a43a3e2d942c5bb93b7b1c77c0ad9a0df95d6/src/toolchain.rs#L178

Nadrieril · 2025-03-11T12:34:02Z

I'll open a rustup issue. I don't have a Windows machine: could you confirm that the same problem happens if instead of charon-driver you try to rustup run just a tiny crate that contains:

#![feature(rustc_private)]
extern crate rustc_driver;
fn main() {
    println!("Hello, World!");
}

?

zjp-CN · 2025-03-11T12:53:58Z

could you confirm that the same problem happens

Yay, I can confirm the dll loading problem happens!

BTW I also noticed the rustup code you linked in the day, and suspect on Windows the loading path should be PATH instead of LD_LIBRARY_PATH :)

Nadrieril · 2025-03-11T12:58:56Z

Nice, I've opened an issue: rust-lang/rustup#4246.

zjp-CN closed this as completed Mar 10, 2025

zjp-CN mentioned this issue Mar 10, 2025

Can we assume the toolchain and components are already set up by user? #589

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Nadrieril reopened this Mar 10, 2025

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Nadrieril mentioned this issue Mar 11, 2025

rustup run doesn't setup the dylib path on windows rust-lang/rustup#4246

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zjp-CN mentioned this issue Mar 12, 2025

Effects of RUSTUP_WINDOWS_PATH_ADD_BIN change rust-lang/rustup#3825

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zjp-CN mentioned this issue Mar 12, 2025

fix(charon CLI): set RUSTUP_WINDOWS_PATH_ADD_BIN=1 on Windows to add rust driver dll to PATH #598

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Nadrieril closed this as completed in #598 Mar 12, 2025

Nadrieril closed this as completed in bb7ae89 Mar 12, 2025

zjp-CN mentioned this issue Mar 12, 2025

Explicitly passing --sysroot should no longer be necessary Artisan-Lab/RAPx#109

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dynamic librustc_driver path is not set by charon #588

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dynamic librustc_driver path is not set by charon #588

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