How do I use the debugger with Rust?

[David-Else]

Hi, I have codelldb installed using the WIKI instructions https://github.com/helix-editor/helix/wiki/Debugger-Configurations#install-debuggers and want to debug a Rust program. I am quite new to debugging, I have done it in VS Code. How do I do it in Helix? I have added:

[[language]]
name = "rust"

[language.debugger]
command = "codelldb"
name = "codelldb"
port-arg = "--port {}"
transport = "tcp"

[[language.debugger.templates]]
name = "binary"
request = "launch"
[[language.debugger.templates.completion]]
completion = "filename"
name = "binary"

[language.debugger.templates.args]
program = "{0}"
runInTerminal = true

launch debug binary asks for binary, I enter the target and get:

I am on RHEL 9 Linux using Kitty, same problem with Debian. Is it still hard coded to use Tmux?

What about the default lldb-vscode? Why are there instructions to install codelldb but not lldb-vscode? How do I get a lldb-vscode binary, do I need to install VS Code?

The WIKI is incredibly confusing. Could someone please explain how to debug Rust? THANKS!

[kirawi]

lldb-vscode is distributed with LLVM as an executable. The wiki entry was created after the fact by someone else.

[ArikRahman]

Is the wiki reliable?

[David-Else]

@kirawi I have managed to download the binary for LLVM from https://github.com/llvm/llvm-project/releases/download/llvmorg-15.0.2/clang+llvm-15.0.2-x86_64-unknown-linux-gnu-rhel86.tar.xz and extracted the file lldb-vscode to ~/bin. Now when I run I get:

I tried to copy the lib directory into bin too, no luck. Am I on the right track, how should I install the binary? Thanks!

[kirawi]

I'm not sure how it goes on Linux, but for me liblldb was in the LLVM/bin folder. Maybe liblldb.so has to be in the same folder as the executable?

[David-Else]

@kirawi I have that lldb-vscode fine and Helix sees it, the problem is the missing lib file liblldb.so.15, I can find it in the lib directory along with a symlink that seems to point to it.. it is all a bit ridiculous to get the debugger working.

Here is my bin dir, it won't find the lib:

[kirawi]

I'm not sure. Here's the documentation for vscode: https://github.com/llvm/llvm-project/tree/main/lldb/tools/lldb-vscode#installation-for-visual-studio-code. Perhaps there's somewhere on LLVM you can ask.

[kirawi]

I checked, and you can build codelldb yourself: https://github.com/vadimcn/vscode-lldb/blob/fe1fb617b273d846b76ba75087e7f35232c9bd9e/BUILDING.md

[the-mikedavis]

The lldb-vscode binary in Nix is defined here https://github.com/NixOS/nixpkgs/blob/nixos-unstable/pkgs/development/compilers/llvm/14/lldb/default.nix (it's included in this repository's devShell in the flake, so it's probably what archseer is using). It looks like a somewhat normal CMAKE build so I assume you just need to follow the build instructions in the LLDB repo

[David-Else]

@the-mikedavis I have made some progress and added it to the WIKI:

https://github.com/helix-editor/helix/wiki/Debugger-Configurations#addendum-for-users-who-cant-make-any-of-the-above-work

I think the entire thing needs re-writing properly and then moving to the documentation section WITH how to actually use the debugger :)

[weiying-chen]

@David-Else Thanks for the instructions. But I still don't know how to launch the debugger.

I did :debug-start, and I got: Failed to start debug session: cannot find binary path.

I couldn't even select anything as instructed:

Now when you run the debugger in Helix select launch debug target and binary, then for example, to debug Rust, target/debug/ and the name of your executable.

[David-Else]

@alexcheninfo I have given up on the debugger, it seems pre-beta and experimental at best :( You should be able to get it running following the instructions I made at https://github.com/helix-editor/helix/wiki/Debugger-Configurations#addendum-for-users-who-cant-make-any-of-the-above-work , at least on Linux. I have no other OS to test it on.

I have asked for help on so many occasions and nobody wants to talk about the debugger, I have no idea if anyone is even using it! I got it running, then to my horror the local variables were reported as memory addresses rather than values! Not sure how that is meant to help debugging?

I don't know why development stopped, it seems it took a year of work to merge it, and then... ?

[weiying-chen]

@David-Else

I see, I'm about to give up too, ha. I'm curious, though, how did you run the debugger?

As I said, I did :debug-start, but I got: Failed to start debug session: cannot find binary path. I couldn't select anything as you instructed.

[David-Else]

Go to your terminal and type lldb-vscode --help to check you have it in your path.

You need to select the built binary for your application in the target/debug/ directory. Auto-complete for the file path might not work due to your .gitignore, you can find it if you type target/ and then you can see auto-complete to find debug and your binary.

[weiying-chen]

Sorry, I'm still confused.

1. Where is this target/debug directory?
2. By selecting, you mean selecting it from inside Helix?

By the way, lldb-vscode is recognize by Helix now:

Binary for debug adapter: /home/alex/.local/bin/lldb-vscode

But when I open a .rs file and run :debug-start inside Helix, I get: Async job failed: none.

[David-Else]

Where is this target/debug directory?

I am assuming you are debugging Rust? When you compile your app with cargo build the executable with debug code is created in /target/debug/filename_of_your_project in your project folder. This is the file you need to open to debug, it is different from languages like JavaScript where you select the source file, you need to select the actual compiled file in Rust.

By selecting, you mean selecting it from inside Helix?

Yes.

[weiying-chen]

I already figured out how. With Space (Space Mode), g (Debug), then l (launch). This let's you select a Rust binary file with autocomplete. Thanks for helping and replying so fast!

By the way, the debugger works fine. The breakpoints work fine. But as you said, the local variables are reported as memory addresses rather than values. I wonder if this is a feature or a bug:

https://i.stack.imgur.com/o7eWO.png

[rkshthrmsh]

Hi @weiying-chen and @David-Else, I was wondering if you were somehow able to access the local variable values from the debugger?

[David-Else]

@rkshthrmsh No I was not, so I added it as an official feature request #7007. It is very strange to me that it is not something everyone is talking about, maybe nobody uses a debugger?

[weiying-chen]

@rkshthrmsh No, I wasn't able. They are still reported as memory addresses (I haven't updated Helix in a while, though). I'll update it one of these days and see.

What about you? You're also seeing memory addresses?

[rkshthrmsh]

@weiying-chen and @David-Else, I tried it today and it seems like values for variables on the stack are shown but only addresses for the heap?

[HealsCodes]

For those here that are trying to debug with helix on macOS:

• install homebrew if you haven't already, then run
• brew install llvm && ln -s $(brew --prefix)/opt/llvm/bin/lldb-vscode $(brew --prefix)/bin/

That'll get you a usable lldb-vscode in your homebrew path without messing up the system llvm / lldb

[HealsCodes]

No, it doesn't - it's just a quick and clean means to get lldb-vscode as I felt that wasn't really addressed yet but asked by the OP.
It still shows addresses for allocated locals:

(that's on helix 23.05 (7f5940b) / llvm 16.0.6)

[HealsCodes]

It looks like the output is down to lldb-vscode having no knowledge of the two commands required to setup rust-pretty printing.

(lldb) command script import "/Users/USER/.rustup/toolchains/stable-aarch64-apple-darwin/lib/rustlib/etc/lldb_lookup.py"
(lldb) command source -s 0 '/Users/USER/.rustup/toolchains/stable-aarch64-apple-darwin/lib/rustlib/etc/lldb_commands'

^-- these two commands get run by rust-lldb as session setup and they enable the decoding of rust parameters into a readable version with actual values.

See my comment on #7007 for details.

[quantonganh]

@rkshthrmsh Please check the updated wiki: https://github.com/helix-editor/helix/wiki/Debugger-Configurations#rust

[rkshthrmsh]

@quantonganh, thanks a ton. It works pretty great now!
@David-Else and @weiying-chen, please note, in case you're still interested.

[David-Else]

@quantonganh Thanks for all your awesome work on the debugger WIKI. I just had a go at re-writing the whole thing to make it more readable and easy to follow for users. I hope I didn't mess anything up! Please could you have a check check to see if you agree with any changes I made?

https://github.com/helix-editor/helix/wiki/Debugger-Configurations/35a284492c002d1d6d9dc923a8c83f586f03409d

or a direct diff:

https://github.com/helix-editor/helix/wiki/Debugger-Configurations/_compare/bf4d6161e14c2f37c7c68dd3334470ffb1e1ef13...35a284492c002d1d6d9dc923a8c83f586f03409d

Thanks!

[David-Else]

@rkshthrmsh Thanks!

[RandomExplosion]

It looks like lldb-vscode (included in lldb itself) is different from vscode-lldb (aka codelldb)
They seem to be two completely different debuggers, which should we be using?

[kirawi]

The default config uses lldb-vscode, but there is also a guide for codelldb on the wiki: https://github.com/helix-editor/helix/wiki/Debugger-Configurations#codelldb-