1# Using a debugger
  2
  3> **DISCLAIMER**: This is not documentation for [configuring Zed's debugger](../debugger.md).
  4> Rather, it is intended to provide information on how to use a debugger while developing Zed itself to both Zed employees and external contributors.
  5
  6## Using Zed's built-in debugger
  7
  8While the Zed project is open you can open the `New Process Modal` and select the `Debug` tab. There you can see to debug configurations to debug Zed with, one for GDB and one for LLDB. Select the configuration you want and Zed will build and launch the binary.
  9
 10Please note, GDB isn't supported on arm Macbooks
 11
 12## Release build profile considerations
 13
 14By default, builds using the release profile (release is the profile used for production builds, i.e. nightly, preview, and stable) include limited debug info.
 15
 16This is done by setting the `profile.(release).debug` field in the root `Cargo.toml` field to `"limited"`.
 17
 18The official documentation for the `debug` field can be found [here](https://doc.rust-lang.org/cargo/reference/profiles.html#debug).
 19But the TLDR is that `"limited"` strips type and variable level debug info.
 20
 21In release builds, this is done to reduce the binary size, as type and variable level debug info is not required, and does not impact the usability of generated stack traces.
 22
 23However, while the type and variable level debug info is not required for good stack traces, it is very important for a good experience using debuggers,
 24as without the type and variable level debug info, the debugger has no way to resolve local variables, inspect them, format them using pretty-printers, etc.
 25
 26Therefore, in order to use a debugger to it's fullest extent when debugging a release build, you must compile a new Zed binary, with full debug info.
 27
 28The simplest way to do this, is to use the `--config` flag to override the `debug` field in the root `Cargo.toml` file when running `cargo run` or `cargo build` like so:
 29
 30```sh
 31cargo run --config 'profile.release.debug="full"'
 32cargo build --config 'profile.release.debug="full"'
 33```
 34
 35> If you wish to avoid passing the `--config` flag on every invocation of `cargo`. You may also change the section in the [root `Cargo.toml`](https://github.com/zed-industries/zed/blob/main/Cargo.toml)
 36>
 37> from
 38>
 39> ```toml
 40> [profile.release]
 41> debug = "limited"
 42> ```
 43>
 44> to
 45>
 46> ```toml
 47> [profile.release]
 48> debug = "full"
 49> ```
 50>
 51> This will ensure all invocations of `cargo run --release` or `cargo build --release` will compile with full debug info.
 52>
 53> **WARNING:** Make sure to avoid committing these changes!
 54
 55## Running Zed with a shell debugger GDB/LLDB
 56
 57### Background
 58
 59When installing rust through rustup, (the recommended way to do so when developing Zed, see the documentation for getting started on your platform [here](../development.md))
 60a few additional scripts are installed and put on your path to assist with debugging binaries compiled with rust.
 61
 62These are `rust-gdb` and `rust-lldb` respectively.
 63
 64You can read more information about these scripts and why they are useful [here](https://michaelwoerister.github.io/2015/03/27/rust-xxdb.html) if you are interested.
 65
 66However, the summary is that they are simple shell scripts that wrap the standard `gdb` and `lldb` commands, injecting the relevant commands and flags to enable additional
 67rust-specific features such as pretty-printers and type information.
 68
 69Therefore, in order to use `rust-gdb` or `rust-lldb`, you must have `gdb` or `lldb` installed on your system. If you don't have them installed, you will need to install them in a manner appropriate for your platform.
 70
 71According to the [previously linked article](https://michaelwoerister.github.io/2015/03/27/rust-xxdb.html), "The minimum supported debugger versions are GDB 7.7 and LLDB 310. However, the general rule is: the newer the better." Therefore, it is recommended to install the latest version of `gdb` or `lldb` if possible.
 72
 73> **Note**: `rust-gdb` is not installed by default on Windows, as `gdb` support for windows is not very stable. It is recommended to use `lldb` with `rust-lldb` instead on Windows.
 74
 75If you are unfamiliar with `gdb` or `lldb`, you can learn more about them [here](https://www.gnu.org/software/gdb/) and [here](https://lldb.llvm.org/) respectively.
 76
 77### Usage with Zed
 78
 79After following the steps above for including full debug info when compiling Zed,
 80You can either run `rust-gdb` or `rust-lldb` on the compiled Zed binary after building it with `cargo build`, by running one of the following commands:
 81
 82```
 83rust-gdb target/debug/zed
 84rust-lldb target/debug/zed
 85```
 86
 87Alternatively, you can attach to a running instance of Zed (such as an instance of Zed started using `cargo run`) by running one of the following commands:
 88
 89```
 90rust-gdb -p <pid>
 91rust-lldb -p <pid>
 92```
 93
 94Where `<pid>` is the process ID of the Zed instance you want to attach to.
 95
 96To get the process ID of a running Zed instance, you can use your systems process management tools such as `Task Manager` on windows or `Activity Monitor` on macOS.
 97
 98Alternatively, you can run the `ps aux | grep zed` command on macOS and Linux or `Get-Process | Select-Object Id, ProcessName` in an instance of PowerShell on Windows.
 99
100#### Debugging Panics and Crashes
101
102Debuggers can be an excellent tool for debugging the cause of panics and crashes in all programs, including Zed.
103
104By default, when a process that `gdb` or `lldb` is attached to hits an exception such as a panic, the debugger will automatically stop at the point of the panic and allow you to inspect the state of the program.
105
106Most likely, the point at which the debugger stops will be deep in the rust standard library panic or exception handling code, so you will need to navigate up the stack trace to find the actual cause of the panic.
107
108This can be accomplished using the `backtrace` command in combination with the `frame select` command in `lldb`, with similar commands available in `gdb`.
109
110Once the program is stopped, you will not be able to continue execution as you can before an exception is hit. However, you can jump around to different stack frames, and inspect the values of variables and expressions
111within each frame, which can be very useful in identifying the root cause of the crash.
112
113You can find additional information on debugging Zed crashes [here](./debugging-crashes.md).