Modular•2w ago

How to configure execution arguments for mojo-lldb in VSCode

Is there a way to pass command-line parameters to the Mojo debugger, so that the following code prints out: I'm looking for the launcher.json configuration that would be equivalent to:

$ mojo debug -D DEBUG ./debug_mode.mojo

$ mojo debug -D DEBUG ./debug_mode.mojo

So that I can get the code below: debug_mode.mojo

from sys import is_defined

alias DEBUG = is_defined["DEBUG"]()

fn main() raises:
    @parameter
    if DEBUG: print("\nIn debug ...")

    print("\nDone.")

from sys import is_defined

alias DEBUG = is_defined["DEBUG"]()

fn main() raises:
    @parameter
    if DEBUG: print("\nIn debug ...")

    print("\nDone.")

To print out the following, when I Start Debugging

text 
In debug ...

Done.

text 
In debug ...

Done.

I believe this is the correct json block to edit, but I cannot find the correct parameters to configure.

    "configurations": [
        {
            "type": "mojo-lldb",
            "request": "launch",
            "name": "Mojo: Debug Current Mojo file",
            "description": "Launch and debug a Mojo file given its path.",
            "mojoFile": "${file}",
            "args": ["-D", "DEBUG"],
            "env": [],
            "cwd": "${workspaceFolder}",
            "runInTerminal": false
        },

    "configurations": [
        {
            "type": "mojo-lldb",
            "request": "launch",
            "name": "Mojo: Debug Current Mojo file",
            "description": "Launch and debug a Mojo file given its path.",
            "mojoFile": "${file}",
            "args": ["-D", "DEBUG"],
            "env": [],
            "cwd": "${workspaceFolder}",
            "runInTerminal": false
        },

as you can see I've tried setting "args": ["-D", "DEBUG"],, but that sets the command line arguments for debug_mode.mojo. If this can only be done in another way, please can someone direct me to the path of enlightenment.

3 Replies

Darkmatter•2w ago

You can invoke it by hand, mojo-lldb, and that opens up some features that vscode doesn't really expose properly, like disassembling functions.

Robert•2w ago

is lldb the default debugger for mojo? I ran into it as I’ve been brute forcing my way thru mojo 😂 idk what the best way to learn programming is but I learn best thru trial by fire pun intended

Darkmatter•2w ago

mojo-lldb is the one you should start with. Occasionally mojo-lldb breaks and you have to go get gdb out since it often doesn't have the feature that is causing the crash.

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How to configure execution arguments for mojo-lldb in VSCode