# Objective

Fixes #54250

`editor: copy file location` copies the row you're on in the
multi-buffer, not the row in the actual file. In a git diff view with
collapsed lines it copies the wrong line number.

## Solution

It read the rows straight off the selection, which is in multi-buffer
coordinates. `ClipboardSelection::for_buffer` already handles this with
`range_to_buffer_range`, so I used the same thing. Path and line now
come from the same buffer.

`range_to_buffer_range` returns nothing when the selection ends in a
different buffer than it starts in, which you can do in a git diff view.
Rather than copy nothing, it falls back to the cursor's buffer.

## Testing

Three tests: a multi-buffer excerpt, a selection dragged across two
files, and a plain single-file editor. The multi-buffer ones fail on
main; the singleton one passes either way, so normal editors are
unaffected.

## Self-Review Checklist:

- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content adheres to Zed's UI standards
([UX/UI](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
and
[icon](https://github.com/zed-industries/zed/blob/main/crates/icons/README.md)
guidelines)
- [x] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable

Release Notes:

- Fixed `editor: copy file location` copying the wrong line number in
multibuffers
([#54250](https://github.com/zed-industries/zed/issues/54250)).

---------

Co-authored-by: Kirill Bulatov <kirill@zed.dev>