feat(inline): add view.inline.deletion_highlight option

[dlyongemallo]

Configure the extent of the DiffDelete background on deleted virt_lines in the diff1_inline layout: "text" (default — just the deleted chars), "full_width" (pad to min(&columns, 250) so the highlight spans the row, matching diff2_horizontal's native look), or "hanging" (skip the leading indent).

[Copilot]

Pull request overview

Adds a new view.inline.full_width_deletions configuration option to improve the visual consistency of deletions rendered via virt_lines in the diff1_inline layout by padding deletions out to the window text width, and triggers repaint on resize so padding stays accurate.

Changes:

• Add optional padding of deleted virt_lines in inline_diff (full_width_deletions) using display width semantics (incl. tabs).
• Add resize-driven repaints for active diff1_inline buffers on WinResized/VimResized (gated by the option).
• Add functional coverage for padding behavior and document the new option in doc/diffview.txt.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
lua/diffview/tests/functional/inline_diff_spec.lua	Adds functional specs verifying padding chunks, tab display width handling, multi-window behavior, and “no window” behavior.
lua/diffview/scene/layouts/diff_1_inline.lua	Registers a global resize autocmd that schedules per-buffer inline repaints when full_width_deletions is enabled.
lua/diffview/scene/inline_diff.lua	Implements widest-window text width detection and pads deletion virt_lines with same highlight group to span row width.
lua/diffview/config.lua	Introduces view.inline.full_width_deletions default + LuaLS type annotations.
doc/diffview.txt	Documents the new view.inline.full_width_deletions option and its behavior.

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[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

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[charbelnicolas]

Hi @dlyongemallo, thanks for taking the time to make this better. Is there a reason why you are using virtual lines specifically? Virtual lines in neovim cannot be selected and copied in case one would like to do so (I don't know if it's my config only) and they also lose the tree-sitter highlights. Check the two examples below. One is using the virtual lines and the other is not. By the way, the virtual lines still do not reach the end of the line, they still get cut off. Would you still like for me to make a new issue about this?

diff1_inline

diff2_horizontal

[dlyongemallo]

@charbelnicolas The reason diff2 layouts don't need virtual lines is because the deleted content is real text in the old buffer, so ext marks (e.g., highlighting) are attached to real line numbers. With the diff1 layout, there is no real buffer to diff against and only the new file's content is available. Inserting real lines in this layout would shift the line numbering and break everything that depends on line numbering. Virtual lines are the only way to add visible content without modifying the buffer.

The diff1 highlighting beyond the end of the actual lines is done by inserting spaces past the end. I had put a cap of 250 on the assumption that this was wider than any user would see, but apparently I was wrong about that. I can fix the cap. I can also run tree-sitter on each virt_lines chunk.

The inability to select/copy virt_lines is a Neovim design choice/hard limitation. If you need to copy the old content, either use a diff2 layout which puts that content into a real buffer, or a screen multiplexer like tmux.

[charbelnicolas]

@charbelnicolas The reason diff2 layouts don't need virtual lines is beacuse the deleted content is real text in the old buffer, so ext marks (e.g., highlighting) are attached to real line numbers. With the diff1 layout, there is no real buffer to diff against and only the new file's content is available. Inserting real lines in this layout would shift the line numbering and break everything that depends on line numbering. Virtual lines are the only way to add visible content without modifying the buffer.

The diff1 highlighting beyond the end of the actual lines is done by inserting spaces past the end. I had put a cap of 250 on the assumption that this was wider than any user would see, but apparently I was wrong about that. I can fix the cap. I can also run tree-sitter on each virt_lines chunk.

The inability to select/copy virt_lines is a Neovim design choice/hard limitation. If you need to copy the old content, either use a diff2 layout which puts that content into a real buffer, or a screen multiplexer like tmux.

That makes a lot of sense, thanks for taking the time to reply, I appreciate it. Tree-sitter support and full line highlight should be enough, thank you!