Launch or attach target using bazel run does not work

[JanJamaszyk-FlyNow]

System Specs

• OS: Linux fb3848ed2f0f 5.4.0-47-generic Set sys modul default encoding to UTF-8 so umlauts etc. can be used in args too #51-Ubuntu SMP Fri Sep 4 19:50:52 UTC 2020 x86_64 GNU/Linux
• VSCode version: Version: 1.49.2
• Commit: e5e9e69aed6e1984f7499b7af85b3d05f9a6883a
• Date: 2020-09-24T16:26:09.944Z
• Electron: 9.2.1
• Chrome: 83.0.4103.122
• Node.js: 12.14.1
• V8: 8.3.110.13-electron.0
• OS: Linux x64 5.4.0-47-generic snap
• Extension version: v1.5.3
• Toolchain version: clang version 10.0.1
• Target: x86_64-pc-linux-gnu
• Thread model: posix
• InstalledDir: /usr/sbin
• Build target: x86_64 GNU/Linux
• Python version:Python 3.8.5

Issue

We are using bazel to build our project and want to use this extension to debug inside the bazel sandbox.
In order to use the bazel sandbox the application needs to be launched using:

bazel run --config=debug //test:test

If we add this command to our launch.json the extension gives the following error:

If we however try to launch the application as a preLaunchTask (run_test_test) the extension can also not find the executable. Even using the ${command:pickProcess} we cannot select the process. I believe the picker is executed before the preLaunchTask ist finished.

Can we add bazel support to launch our application directly using bazel?

launch.json

        {
            "name": "Attach to Test",
            "type": "lldb",
            "request": "attach",
            "preLaunchTask": "run_test_test",
            "sourceMap": {
                "/proc/self/cwd": "${workspaceFolder}",
            },
            "initCommands": [
                "settings set target.disable-aslr false"
            ],
            "program": "${workspaceFolder}/bazel-bin/test/test",
            //"pid": "${command:pickProcess}"
        },
        {
            "name": "Launch Test",
            "type": "lldb",
            "request": "launch",
            "sourceMap": {
                "/proc/self/cwd": "${workspaceFolder}",
            },
            "initCommands": [
                "settings set target.disable-aslr false"
            ],
            "program": "bazel",
            "args": [
                "run",
                "--config=debug",
                "//test:test"
            ],
        },

[vadimcn]

You've set up launch config to debug bazel itself, not the process it runs. lldb currently does not support debugging of child processes. You will need to locate the actual executable under bazel-bin// and launch it directly.

[JanJamaszyk-FlyNow]

Thanks Vadim,
this is what we are doing today, unfortunately this does not respect the bazel sandbox.
Especially using things like bazel runfiles:
https://github.com/bazelbuild/bazel/blob/master/tools/cpp/runfiles/runfiles_src.h
becomes impossible. The only clean solution we currently see is "native bazel support" the same way you support rust cargo.
Could you please look into the feasibility of this? We absolutely could support you with providing stripped down minimal examples!
Best,
Jan

[vadimcn]

Cargo has a mode in which it logs compilation outputs in JSON format, which is parsed by CodeLLDB and used to locate the binary to launch. As far as I know, Bazel does not provide anything like that.

This might help in your case. If you can find a way to inject a custom wrapper script into bazel run, you could use the uri interface to start a debug session. In the worst case, you could put debugger attach into your binary (see the first example).

[vadimcn]

Specifically, try this:

• Create codelldb.sh:

  #!/bin/bash
  code --open-url "vscode://vadimcn.vscode-lldb/launch/command?LD_LIBRARY_PATH=$LD_LIBRARY_PATH&$*"

• chmod +x codelldb.sh
• bazel run --run_under=codelldb.sh //<package>:<target>

[JanJamaszyk-FlyNow]

Thanks Vadim,
especially for the sample, I tried that before but got stuck on another related error:
#404
Thank you so much for your help!
Jan