Run and Debug codelens link buttons for main (non test) entry point launch with differing cwd paths

[Keshi]

Observed behaviour: In the scenario of an bin package inside a virtual workspace, such as in this minimal example (https://github.com/Keshi/minimal-virtual-workspace), choosing to Run or Debug the main function using the codelens buttons results in different working directories.
If the application is one that expects to dynamically load a settings or asset file relative to the cwd, then the application will always fail to load the file through one of either Run or Debug.

Expected/Desired behaviour: Run and Debug codelens buttons both launch the application using the same cwd behaviour (as observed by the application) as Run currently does.

rust-analyzer version: rust-analyzer version: 0.3.1906-standalone (e4a405f 2024-03-31)
rustc version: rustc 1.77.1 (7cf61ebde 2024-03-27)
editor or extension: VSCode, rust-analyzer 0.3.1906

relevant settings: (eg. client settings, or environment variables like CARGO, RUSTC, RUSTUP_HOME or CARGO_HOME)

repository link (if public, optional):
https://github.com/Keshi/minimal-virtual-workspace

[roife]

Related to #13022 and #15993.

Should we make Run and Debug both use the package-root as cwd?

Or we could introduce a setting and let users decide whether to use workspace-root or package-root.

[Keshi]

I think that Run should keep its current behaviour, since it provides a cwd matching the user's context or scope of what they have opened using their IDE (for example, the whole workspace in a multi-package project), as if they had used cargo run or cargo run -p some-pkg-name from the terminal from the same context, or from opening a terminal in an IDE opened to the project. I think that Debug should be changed to use the same behaviour as that of Run for cwd, in the situation of an application (not a #[test]) launch. Changing Debug to match Run for cwd would thus make those 3 ways of starting an application consistent with each other for cwd, alleviating the issue.

I don't think Run and Debug should both always use package-root as cwd, as then you'd have surprising behaviour compared to cargo run in the terminal from the same user context, but in the case of a single package not in another workspace, that would end up being the effective behaviour regardless.

I think there is definitely an argument to be made for always using package-root for cwd in every scenario, but I also think that would only make sense if cargo run -p and cargo run in a workspace with a default member were also doing the same thing, which it is not.

[TieWay59]

pub fn current_dir() -> io::Result<PathBuf>
Returns the current working directory as a [PathBuf].

I think the current working directory definition is not clear enough in docs, it's itchy to guess what it will return.

I prefer the cwd = current workspace directory and expose a new API like current package root.

Debug should work as Run in the same way.