# Rust Adapter
## CLI
Start: `dbg start rust <crate-name> [--break file.rs:line] [--run]`
The `<crate-name>` is the Cargo package name (e.g., `my-crate`), **not** a file path. Do not pass `./target/debug/...` — dbg builds and locates the binary automatically.
## Preconditions
| `dbg` | `which dbg` | `cargo install dbg-cli` — ensure `~/.cargo/bin` is in PATH |
| `lldb` | `which lldb-20 \|\| which lldb` | `sudo apt install lldb-20` or `brew install llvm` |
If `sudo` is not available, check if lldb is already installed under a versioned name (`lldb-18`, `lldb-16`, etc.) with `which lldb-{20,18,16,15,14} 2>/dev/null`. Set `LLDB_BIN=lldb-<version>` if the default `lldb` is not the right one.
## Build
```bash
cargo build -p <crate> # debug (default)
```
Binary: `target/debug/<crate_name>` (hyphens → underscores). The `dbg start` command builds automatically if needed.
## Breakpoint Patterns
| `rust_panic` | Catch any panic |
| `rust_begin_unwind` | Catch unwinding |
| `file.rs:42` | File and line |
## Type Display
- **Option/Result**: `$variants$` layout. `$variant$0` = None/Err, `$variant$` with `value.__0` = Some/Ok
- **String/&str**: Fat pointer — `pointer` field shows UTF-8 bytes
- **PathBuf**: Nested `inner.inner...ptr.pointer` — look for `pointer` field
- **Vec<T>**: `ptr`, `len`, `cap`
## Async / Tokio
- Locals appear as `{async_block_env#N}` struct fields
- `tokio-rt-worker` threads are executor threads — look for your crate's frames in `bt`
- Set breakpoints on the function name, not executor internals
## Common Failures
| Binary not found | Hyphens become underscores: `my-crate` → `target/debug/my_crate` |
| Breakpoint pending (0 locations) | `image lookup --name <partial>` to find correct symbol |
| Variables `<unavailable>` | Step to assignment line, or ensure debug build |
| DWARF indexing slow | Normal on first load |