regression under openbsd: undefined reference to `_Unwind_Resume`

[semarie]

I have noted a regression in make check starting from 263fdfe (found with bisect).

the failing test is one of doc-trpl-no-stdlib. The fail occurs with stage1 and with stage2 (it have help a lot for bisect: only 50 min for 1 step of bisect)

I extract the example to a standalone file, and manually run rustc: the error is a linking error:

original.o(.text._ZN6option15Option$LT$T$GT$8and_then21h10563965396030871015E+0xa0): In function `option::Option$LT$T$GT$::and_then::h10563965396030871015': undefined reference to `_Unwind_Resume'

it seems -lgcc isn't passed by rustc, whereas the symbol _Unwind_Resume was present in option::Option<T>::and_then.

Any help would be appreciate.

[Virtlink]

I have the same issue. It worked fine in nightly c89de2c (2015-03-28), but now in nightly 47def3e (2015-04-13) I get these errors when trying to link my standalone kernel with libcore:

libkernel-7b2dcbc423fd2cc0.a(r-core-core-bffd6497cd08eb80.o):
In function `core::option::Option<T>::and_then<(&core::fmt::ArgumentV1, &&str),closure>':
libcore/src/option.rs:627: undefined reference to `_Unwind_Resume'
In function `core::option::Option<T>::and_then<(&core::fmt::rt::v1::Argument, &&str),closure>':
libcore/src/option.rs:627: undefined reference to `_Unwind_Resume'

It only happens when I use my custom target.json:

{
    "data-layout": "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128",
    "llvm-target": "x86_64-unknown-linux-gnu",
    "target-endian": "little",
    "target-pointer-width": "64",
    "os": "orion",
    "arch": "x86_64",
    "pre-link-args": ["-m64"],
    "no-compiler-rt": true,
    "disable-redzone": true,
    "eliminate-frame-pointer": false,
    "morestack": false
}

If I try to add _Unwind_Resume manually:

#[no_mangle]
#[allow(non_snake_case)]
pub extern "C" fn _Unwind_Resume(_ex_obj: *mut ()) { }

...Rust gives me this error instead:

src/lib.rs:118:1: 118:55 error: symbol `_Unwind_Resume` is already defined
src/lib.rs:118 pub extern "C" fn _Unwind_Resume(_ex_obj: *mut ()) { }
               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Is there a solution or workaround?

rustc 1.0.0-nightly (47def3ef2 2015-04-13) (built 2015-04-13)
binary: rustc
commit-hash: 47def3ef27a2e027f1a93ef7870ff131ee7926fd
commit-date: 2015-04-13
build-date: 2015-04-13
host: x86_64-unknown-linux-gnu
release: 1.0.0-nightly

[semarie]

@Virtlink you could try to explicitly link with libgcc by providing -lgcc on rustc command-line.

[Virtlink]

@semarie Can that be done through Cargo too? As I've only used Cargo up to now.

[semarie]

I really don't known... (I don't have cargo on openbsd). You could try to add
#[link(name="gcc")] in your file.