Linking with cc gets a spurious return code on ARM

[chris-morgan]

Steps to reproduce:

1. Take a build of rustc for ARM (specifically, gnueabi; gnueabihf is untested and may or may not exhibit this problem). Luqman has one you can use at http://luqman.ca/rust-builds/.
2. Attempt to compile something, e.g. echo 'fn main(){}' | rustc -.

The binary is created successfully and will run fine (I finally have rust-http running on my Android-with-Ubuntu-inside-it tablet!), but the .o file remains around and rustc also dies with a spurious return code from the linker.

error: linking with `cc` failed with code 1081742352
note: cc arguments: -L/home/chris/opt/rust/lib/rustc/arm-unknown-linux-gnueabi/lib -marm -o /tmp/rust_out /tmp/rust_out.o -L/home/chris/opt/rust/lib/rustc/arm-unknown-linux-gnueabi/lib -lstd-6c65cf4b443341b1-0.9-pre -L/home/chris/opt/rust/lib/rustc/arm-unknown-linux-gnueabi/lib -lrustuv-d4277cd5f62aa99-0.9-pre -lrustrt -lrt -lpthread -L/tmp/.rust -L/tmp -lrt -ldl -lm -lmorestack -lrustrt -Wl,-rpath,$ORIGIN/../home/chris/opt/rust/lib/rustc/arm-unknown-linux-gnueabi/lib -Wl,-rpath,/home/chris/opt/rust/lib/rustc/arm-unknown-linux-gnueabi/lib -Wl,-rpath,/scratch/laden/local/lib/rustc/arm-unknown-linux-gnueabi/lib
note: 
error: aborting due to previous error
task '<unnamed>' failed at 'explicit failure', ../src/libsyntax/diagnostic.rs:101
task '<unnamed>' failed at 'explicit failure', ../src/librustc/rustc.r:396

(I typed that out by hand; it's possible that it may not be entirely correct.)

The claimed return code is well outside what I believe to be the valid range for return codes (I think it's supposed to be an unsigned 8-bit value) and is different each time. I presume that it's not retrieving the return value correctly. If one runs cc manually with the specified arguments, the return code is 0, as expected.

[miselin]

It could be worth doing a small testcase with a small C program + libuv on the same ARM target/host that spawns cc and peeks at the exit status reported. If libuv is reporting a weird exit status to the exit callback, without any of our Rust runtime doing anything funky, then this might be a libuv bug.

Otherwise, #10109 may resolve this once it lands, or at least make it clearer what the issue is.

[chris-morgan]

Given this source:

use std::run::{Process, ProcessOptions};

fn main() {
    println!("{}", Process::new("echo", [~"foo"], ProcessOptions::new()).finish());
}

This returns 0 every time on my x86_64 machine, but on my ARM machine it returns values like 1080882192, 1081480208, 1081672720 and 1082012688.

I guess that narrows the problem down to std::rt::io::process getting the exit status wrong.

[chris-morgan]

This bug no longer occurs.