Julia VS Code debugger crash

[l8l]

OS: Linux, Debian
Julia version: Most recent stable release

---

I am trying to debug code in the julia vscode debugger. Usually all goes well but when setting a breakpoint inside a function, that is called by an imported library, the debugger crashes when trying to display the variables in the scope.

More specifically, in the vscode settings I set

"julia.debuggerDefaultCompiled": [
    "ALL_MODULES_EXCEPT_MAIN",
    "-Lux.",
    "-Lux.Training",
    "-Lux.Training.compute_gradients",
]

and I try to debug the code where I use a custom loss function in some machine learning Lux code, where the loss function is called by the Lux-function, that computes gradients. For reference, here is a snippet of the code:

loss_function = function(model,ps,state,data)
    (x,y) = data
    y_p, state = model(x,ps,state)
    stats = []
    return mean((y_p.-y).^2), state, stats
end


_, loss, _, tstate = Training.single_train_step!(vjp, loss_function, data, tstate)

The code runs fine without debugger mode. However, even though the debugger jumps to the breakpoint, which is set at the line where you see stats = [], it directly thereafter crashes, when trying to display the variables in scope, with the following error:

> Connecting to debugger… Done!

┌ Error: Some Julia code in the VS Code extension crashed
└ @ VSCodeDebugger ~/.vscode-server/extensions/julialang.language-julia-1.79.2/scripts/error_handler.jl:15
ERROR: AssertionError: !(is_generated(method))
Stacktrace:
[1] compute_corrected_linerange
@ ~/.vscode-server/extensions/julialang.language-julia-1.79.2/scripts/packages/JuliaInterpreter/src/utils.jl:441 [inlined]
[2] scopes_request(conn::VSCodeDebugger.JSONRPC.JSONRPCEndpoint{Base.PipeEndpoint, Base.PipeEndpoint}, state::VSCodeDebugger.DebugAdapter.DebuggerState, params::VSCodeDebugger.DebugAdapter.ScopesArguments)
@ VSCodeDebugger.DebugAdapter ~/.vscode-server/extensions/julialang.language-julia-1.79.2/scripts/packages/DebugAdapter/src/debugger_requests.jl:561
[3] (::VSCodeDebugger.DebugAdapter.var"#129#155"{VSCodeDebugger.DebugAdapter.DebuggerState})(conn::VSCodeDebugger.JSONRPC.JSONRPCEndpoint{Base.PipeEndpoint, Base.PipeEndpoint}, params::VSCodeDebugger.DebugAdapter.ScopesArguments)
@ VSCodeDebugger.DebugAdapter ~/.vscode-server/extensions/julialang.language-julia-1.79.2/scripts/packages/DebugAdapter/src/packagedef.jl:56
[4] dispatch_msg(x::VSCodeDebugger.JSONRPC.JSONRPCEndpoint{Base.PipeEndpoint, Base.PipeEndpoint}, dispatcher::VSCodeDebugger.JSONRPC.MsgDispatcher, msg::Dict{String, Any})
@ VSCodeDebugger.JSONRPC ~/.vscode-server/extensions/julialang.language-julia-1.79.2/scripts/packages/JSONRPC/src/typed.jl:67
[5] (::VSCodeDebugger.DebugAdapter.var"#146#172"{VSCodeDebugger.var"#3#4"{Tuple{String, String}}, VSCodeDebugger.JSONRPC.JSONRPCEndpoint{Base.PipeEndpoint, Base.PipeEndpoint}, VSCodeDebugger.JSONRPC.MsgDispatcher})()
@ VSCodeDebugger.DebugAdapter ~/.vscode-server/extensions/julialang.language-julia-1.79.2/scripts/packages/DebugAdapter/src/packagedef.jl:76

Does anybody know why and how to resolve this? Thanks a lot!

[l8l]

Any ideas?

[l8l]

The discussion in this julia discourse thread revealed that the error could be caused by generated functions, that are not accepted by the julia interpreter, presumably due to this assertion on line 447. Specifically @littlelib came up with the following minimal reproducible example:

@generated function foo(x)
    Core.println(x)
    return :(x * x)
end

foo(16)

┌ Error: Some Julia code in the VS Code extension crashed
└ @ VSCodeDebugger 
~\.vscode\extensions\julialang.language-julia-1.124.2\scripts\error_handler.jl:15
ERROR: AssertionError: !(is_generated(method))

Why does the debugger not work for generated functions and what can we do about it?