Is it possible to use a debugger with Bevy?

[AlexOkafor]

Hi!
I was trying to write some unit tests for systems and decided to try to use the CodeLLDB debugger for rust. A simple hello world program seems to work:

// use bevy::prelude::*;

fn main() {
    // App::new()
    //     .add_plugins(MinimalPlugins)
    //     .add_system(my_sys)
    //     .run();
    my_sys();
}

fn my_sys() {
    print!("hmm?");
}

but the second I add in a Bevy app like so...:

use bevy::prelude::*;

fn main() {
    App::new()
        .add_plugins(MinimalPlugins)
        .add_system(my_sys)
        .run();
    // my_sys();
}

fn my_sys() {
    print!("hmm?");
}

the debugger fails:

with this output log:

Initial debug configuration: {
  type: 'lldb',
  request: 'launch',
  name: "Debug executable 'bug'",
  cargo: {
    args: [ 'build', '--bin=bug', '--package=bug' ],
    filter: { name: 'bug', kind: 'bin' }
  },
  args: [],
  cwd: '${workspaceFolder}',
  __configurationTarget: 5
}
Raw artifacts:
{
  fileName: 'g:\\gamedev\\projects\\learn_rust\\bug\\target\\debug\\bug.exe',
  name: 'bug',
  kind: 'bin'
}
Filtered artifacts: 
{
  fileName: 'g:\\gamedev\\projects\\learn_rust\\bug\\target\\debug\\bug.exe',
  name: 'bug',
  kind: 'bin'
}
Resolved debug configuration: {
  type: 'lldb',
  request: 'launch',
  name: "Debug executable 'bug'",
  args: [],
  cwd: '${workspaceFolder}',
  __configurationTarget: 5,
  relativePathBase: 'g:\\gamedev\\projects\\learn_rust\\bug',
  program: 'g:\\gamedev\\projects\\learn_rust\\bug\\target\\debug\\bug.exe',
  _adapterSettings: {
    displayFormat: 'auto',
    showDisassembly: 'auto',
    dereferencePointers: true,
    suppressMissingSourceFiles: true,
    evaluationTimeout: 5,
    consoleMode: 'commands',
    sourceLanguages: [ 'rust' ],
    terminalPromptClear: null,
    evaluateForHovers: true,
    commandCompletions: true,
    reproducer: false
  }
}
[adapter\src\terminal.rs:104] FreeConsole() = 1
[adapter\src\terminal.rs:105] AttachConsole(pid) = 1
Debug adapter exit code=3221225477 (0xc0000005), signal=null.

Has anyone been able to successfully use a debugger with Bevy? Or is the consensus to just stick to println debugging?

[Nilirad]

It looks like you're using VSCode. With the rust-analyzer extension you can press the “Debug” button above the main function of an example or a binary, and it should work (At least it does for me).

[bjorn3]

Exit code 0xc0000005 is an access violation. In other words the windows equivalent of SIGSEGV. The log suggests that it is lldb which crashes. This would be a bug in lldb as a debugger should never crash, even if the debugged program severely misbehaves.