rust-debugging

Rust Debugging

Purpose

Guide agents through debugging Rust programs: GDB/LLDB with Rust pretty-printers, backtrace configuration, panic triage, async debugging with tokio-console, and #[no_std] debugging strategies.

Triggers

• "How do I use GDB/LLDB to debug a Rust binary?"
• "How do I get a full backtrace from a Rust panic?"
• "How do I debug async Rust / Tokio?"
• "Rust pretty-printers aren't working in GDB"
• "How do I debug a Rust panic in production?"
• "How do I use dbg! and tracing in Rust?"

Workflow

1. Build for debugging

# Debug build (default) — full debug info, no optimization
cargo build

# Release with debug info (for profiling real workloads)
cargo build --release --profile release-with-debug
# Or configure in Cargo.toml:
# [profile.release-with-debug]
# inherits = "release"
# debug = true

# Run directly
cargo run
cargo run -- arg1 arg2

2. GDB with Rust pretty-printers

# Use rust-gdb wrapper (sets up pretty-printers automatically)
rust-gdb target/debug/myapp

# Or set up manually in ~/.gdbinit:
# python
# import subprocess, sys
# ...

Common GDB session for Rust:

# Basic
(gdb) break main
(gdb) run arg1 arg2
(gdb) next           # step over
(gdb) step           # step into
(gdb) continue

# Rust-aware inspection
(gdb) print my_string     # Shows String content via pretty-printer
(gdb) print my_vec        # Shows Vec elements
(gdb) print my_option     # Shows Some(value) or None
(gdb) info locals

# Break on panic
(gdb) break rust_panic
(gdb) break core::panicking::panic

# Backtrace
(gdb) bt              # Short backtrace
(gdb) bt full         # Full with locals

3. LLDB with Rust pretty-printers

# Use rust-lldb wrapper
rust-lldb target/debug/myapp

# Manual setup
lldb target/debug/myapp
(lldb) command script import /path/to/rust/lib/rustlib/etc/lldb_lookup.py
(lldb) command source /path/to/rust/lib/rustlib/etc/lldb_commands

Common LLDB session:

(lldb) b main::main
(lldb) r arg1 arg2
(lldb) n              # next (step over)
(lldb) s              # step into
(lldb) c              # continue
(lldb) frame variable # show locals
(lldb) p my_string    # print variable with pretty-printer
(lldb) bt             # backtrace
(lldb) bt all         # all threads