Debugging Rust Web Assembly

[SGumbles]

Apologies if this is a newbie thing to have discovered.

I'm brand new to Zed having just made the switch over from VS Code. One of the things I liked about VS Code was you can set breakpoints on your Rust code and they will get hit from a debugging session in Chrome. This wasn't happening in Zed so I (errr ahh, *cough cough* AI) did some digging and found this trick.

1. I copied the Zed JavaScript debugger, which on my machine is at ~/.local/share/zed/debug_adapters/JavaScript/JavaScript_v1.140.0/js-debug, into a temporary folder at ~/zed-js-debug-dwarf
2. Inside js-debug in that directory I ran npm install @vscode/dwarf-debugging
3. In my Zed config file I added this

 "dap": {
      "JavaScript": {
        "binary": "<MY HOME DIR>/zed-js-debug-dwarf/js-debug/src/dapDebugServer.js"
      }
    }

That was essentially it. This is my debug config file

{
    "adapter": "JavaScript",
    "label": "Launch Chrome (Trunk)",
    "type": "chrome",
    "request": "launch",
    "url": "http://127.0.0.1:8080/",
    "webRoot": "$ZED_WORKTREE_ROOT/dist",
    "runtimeExecutable": "<MY HOME DIR>/.cache/ms-playwright/chromium-1243/chrome-linux64/chrome"
  }

The blob of javascript inside js-debug (dapDebugServer.js) already looks for @vscode/dwarf-debugging because the enableDWARF flag is on by default, so you don't even need to set it in your debug config block.

So now the javascript debugger can read in the debug symbols from your .wasm file and can talk to the Chrome debugger. I didn't have to do anything special to get the debug symbols in the wasm file, the project is just a simple wasm-bindgen project that I'm running with trunk via trunk serve.

This is really handy for me.

The question I have is why is this not enabled by default? Licensing? The @vscode/dwarf-debugging module is large, 53MB, but other than that, this seems like a very simple QoL addition for WASM people. Perhaps this is just a rookie mistake and there is something in the config files that I missed!

Anyways, I'm really enjoying Zed so far, keep up the great work!

[SGumbles]

Would be happy to attempt the leg work and make a PR if this is something people would be interested in!