Debug unit test code lens fails with a cargo linking failure

[adaszko]

Hi 👋

When I click the "Debug" code lens over a unit test, it fails with a linking error:

error: linking with `cc` failed: exit code: 1
[...]
  = note: /usr/bin/ld: cannot find -lpython3.6m
          collect2: error: ld returned 1 exit status

The source of the problem is this: The PATH environment variable needs to include the /opt/miniconda/bin directory. The problem is, even when I put in the env section in launch.json, it's seems like it's not being respected because it doesn't fix the problem:

{
    "type": "lldb",
    "request": "launch",
    "name": "Debug benchmark 'bench_main'",
    "env": {
        "PATH": ".:/root/.cargo/bin:/opt/miniconda/bin:/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin"
    },
    "cargo": {
        "args": [
            "test",
            "--no-run",
            "--bench=bench_main",
            "--package=ddx"
        ],
        "filter": {
            "name": "bench_main",
            "kind": "bench"
        }
    },
    "args": [],
    "cwd": "${workspaceFolder}"
}

OTOH, if I build the code via this launch configuration:

{
	"type": "cargo",
	"command": "build",
	"env": {
		"PATH": ".:/root/.cargo/bin:/opt/miniconda/bin:/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin"
	},
	"problemMatcher": [
		"$rustc"
	],
	"group": "build",
	"label": "rust: cargo build"
}

there isn't any linking problem and the code builds fine. So I thought I could use the preLaunchTask in launch.json:

"preLaunchTask": "rust: cargo build",

but it also is being ignored and doesn't address the linking problem.

[lnicola]

See rust-lang/vscode-rust#887 for previous discussion:

So the crucial question is: Where does rust-analyzer take the recipe to build from for the "Debug unit test" code lens?

I think we invoke cargo build around editors/code/src/debug.ts, thus losing the server environment variables.

[vsrs]

@adaszko,

You may try rust-analyzer.runnableEnv setting:

"rust-analyzer.runnableEnv": {
    "PATH": ".:/root/.cargo/bin:/opt/miniconda/bin:/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin"
}

[adaszko]

@vsrs I have it configured because I use for "Run test" code lens and it works for that. It doesn't work unfortunately for "Debug unit test" code lens.

[vsrs]

Ups, I forgot that we do not use runnableEnv to get executable:
https://github.com/rust-analyzer/rust-analyzer/blob/b0f20a795d6b1f8d36d1cbe294e54ac592b98f5e/editors/code/src/debug.ts#L105-L106

Looks like it should be enough to reuse task env vars in getDebugExecutable and Cargo::executableFromArgs functions:
https://github.com/rust-analyzer/rust-analyzer/blob/b0f20a795d6b1f8d36d1cbe294e54ac592b98f5e/editors/code/src/debug.ts#L128-L134