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Comment by red75prime | Hacker News Reader

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red75prime·

I'm a little rusty on the topic, but it seems ([0]) that adding `#[no_mangle]` before `panic_fmt` should fix it.

[0] https://github.com/rust-lang/rust/issues/38281

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Even specifying `eh_unwind_resume` as a lang item gives me a linking error in debug builds.

Did you define them exactly the same way? Every aspect has to be identical; extern, no mangle, function name, arguments, lang item.

If this happens to be open source, I can take a look at it.

I just whipped this up yesterday to test if I was still having the same issues. Debug fails to build with a linking error "undefined reference to `_Unwind_Resume`". Release build works fine.

I'm using rustc 1.25.0-nightly on Ubuntu 17.10

https://gist.github.com/jefftime/d7e96461138b5aa6895550b63ca...

The lang item symbol names need to be prefixed with rust_ like this: https://gist.github.com/steveklabnik/5abd59a8fe7e5abda3db58b...

This didn't fix the compilation errors for me. I can set my own no_mangle pub extern `_Unwind_Resume` function (without declaring it a lang_item) and fix the undefined reference that way, but I'm pretty sure that's not how one's supposed to solve this

Hm, it compiled for me. Well, it didn't know about the C functions that were being linked in, but it didn't complain about the lang items.

You should file a bug, maybe.

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