Script to add Rust specific pretty-printing to the LLDB debugger.
With the recent removal of Rust specific pretty printing from CodeLLDB, debugging Rust, especially enums, has become quite painful.
This script is meant as a temporary fix until the situation of the ecosystem improves, see Compatability.
To load the script into your lldb debugger instance, execute the following lldb command:
command script import /path/to/rust_prettifier_for_lldb.py
rust_prettifier_for_lldb.py
is the only file from this Repository that you actually need. You can download it separately from the
Releases section.
To use this script with VSCode debug adapters you have to instruct them to execute the same lldb command as above before the actual debugging session.
Either place rust_prettifier_for_lldb.py into your .vscode folder,
or replace ${workspaceFolder}/.vscode/rust_prettifier_for_lldb.py
with the actual path you chose in the examples below.
For the
CodeLLDB
extension, add the preRunCommands json tag from the example below
to your launch configuration(s) or alternatively to your user settings under
lldb.launch.preRunCommands.
It is also recommended to set "expressions": "simple" to fix an issue with
the array subscript operator ([..]) in the Debug Watch Window.
Here's an example configuration for your .vscode/launch.json:
{
"version": "0.2.0",
"configurations": [
{
"type": "lldb",
"request": "launch",
"name": "Debug",
"cargo": {
"args": [
"build",
],
"filter": {
"name": "NAME_OF_YOUR_BINARY_HERE",
"kind": "bin"
}
},
"expressions": "simple",
"preRunCommands": [
// !! change this path if you placed the script somewhere else !!
"command script import ${workspaceFolder}/.vscode/rust_prettifier_for_lldb.py"
],
"args": [],
},
]
}
For the lldb-dap extension, add the initCommands JSON tag to your .vscode/launch.json configuration(s), as shown in the example below:
{
"version": "0.2.0",
"configurations": [
{
"type": "lldb-dap",
"request": "launch",
"name": "Debug",
"program": "NAME_OF_YOUR_BINARY_HERE",
"args": [],
"cwd": "${workspaceFolder}",
"initCommands": [
// !! change this path if you placed the script somewhere else !!
"command script import ${workspaceFolder}/.vscode/rust_prettifier_for_lldb.py"
],
}
]
}
This script was developed for LLDB Version 19.0.0, aswell as 19.1.0-codelldb (version currently bundled by
CodeLLDB).
At the time of writing, it is known to work well with the latest stable version Rust (1.82.0).
Initially this did not support Windows, although @jesnor was able to get it partially working. Any improvements on that front would of course be welcomed.
If you are using older versions of Rust or LLDB this script might not work for you.
Due to the changing nature of the Rust Standard Library internals aswell as the LLDB representation of them, this will never be more than a temporary hack that's constantly in danger of becoming outdated. The hope is that Rust's own Pretty Printers will eventually ship in a functional state, superseeding this temporary bandaid.
The plan for this script is to live at head, and hopefully get retired sooner rather than later.
I'm happy to accept pull requests to improve this script or even add support for commonly used collection types of third party crates, as long as you supply testcases to make sure your additions can be maintained.
Note (2025-01-18): There are known cases where it does not seem feasible to report the correct answer without fixing the upstream issues in Rust or LLVM. You might in rare cases even get incorrect results.
Thank you to Vadim Chugunov (@vadimcn) for the wonderful CodeLLDB and the starting point for this script.
If this script has helped you out a a Github Star ✨ would make me very happy, and maybe help demonstrate to the Rust Project Maintainers that a solid solution for debugging Rust is something that many people desire.