Use relative paths as file-relative when parsing a file

[kubouch]

Description

Currently affects:

• source
• use
• overlay add

If one of the above is used inside a script with a relative filename as an argument, the path is assumed to be relative to the parsed file, not cwd.

Also applies to scripts parsed with nu-check. However, nu-check used inside a script is not affected as we would need to track the currently parsed file within the engine.

Fixes #5853

Related: #4842

Tests

Make sure you've done the following:

• Add tests that cover your changes, either in the command examples, the crate/tests folder, or in the /tests folder.
• Try to think about corner cases and various ways how your changes could break. Cover them with tests.
• If adding tests is not possible, please document in the PR body a minimal example with steps on how to reproduce so one can verify your change works.

Make sure you've run and fixed any issues with these commands:

• cargo fmt --all -- --check to check standard code formatting (cargo fmt --all applies these changes)
• cargo clippy --workspace --features=extra -- -D warnings -D clippy::unwrap_used -A clippy::needless_collect to check that you're using the standard code style
• cargo test --workspace --features=extra to check that all the tests pass

[hustcer]

Great, I've looking forward to this feature for a long time

[jmgilman]

I'm struggling to try to understand what the change was here. Are relative paths relative to the current working directory or are they relative to the location of the file being executed?

On the latest version (0.71.0), if I have the following:

/tmp/test/mod.nu

export def hello [name: string] {
    $"hello ($name)!"
}

/tmp/test/test.nu

use mod.nu

mod hello "world"

And I attempt to run the script:

❯ nu /tmp/test.nu   
Error: nu::parser::module_not_found (link)

  × Module not found.
   ╭─[/tmp/test.nu:1:1]
 1 │ use mod.nu
   ·     ───┬──
   ·        ╰── module not found
 2 │ 
   ╰────
  help: module files and their paths must be available before your script is run as parsing occurs before anything is evaluated

It doesn't find the module. Looking at the tests introduced by this PR, it's using nu-check, which ironically passes in this case:

❯ nu-check /tmp/test.nu
true

This seems like a bug, but I could be misunderstanding the desired effect here.

[WindSoilder]

@jmgilman Hi, I can't reproduce it on latest main, would you please verify it again?