delta shell completion diff (left is generated, right is checked) (for https://github.com/Homebrew/homebrew-core/pull/201834)

delta.bash.diff

22c22
<             opts="-@ -n -s -w -h -V --blame-code-style --blame-format --blame-palette --blame-separator-format --blame-separator-style --blame-timestamp-format --blame-timestamp-output-format --color-only --config --commit-decoration-style --commit-regex --commit-style --dark --default-language --detect-dark-light --diff-args --diff-highlight --diff-so-fancy --diff-stat-align-width --features --file-added-label --file-copied-label --file-decoration-style --file-modified-label --file-removed-label --file-renamed-label --file-style --file-transformation --generate-completion --grep-context-line-style --grep-file-style --grep-header-decoration-style --grep-header-file-style --grep-line-number-style --grep-output-type --grep-match-line-style --grep-match-word-style --grep-separator-symbol --hunk-header-decoration-style --hunk-header-file-style --hunk-header-line-number-style --hunk-header-style --hunk-label --hyperlinks --hyperlinks-commit-link-format --hyperlinks-file-link-format --inline-hint-style --inspect-raw-lines --keep-plus-minus-markers --light --line-buffer-size --line-fill-method --line-numbers --line-numbers-left-format --line-numbers-left-style --line-numbers-minus-style --line-numbers-plus-style --line-numbers-right-format --line-numbers-right-style --line-numbers-zero-style --list-languages --list-syntax-themes --map-styles --max-line-distance --max-syntax-highlighting-length --max-line-length --merge-conflict-begin-symbol --merge-conflict-end-symbol --merge-conflict-ours-diff-header-decoration-style --merge-conflict-ours-diff-header-style --merge-conflict-theirs-diff-header-decoration-style --merge-conflict-theirs-diff-header-style --minus-empty-line-marker-style --minus-emph-style --minus-non-emph-style --minus-style --navigate --navigate-regex --no-gitconfig --pager --paging --parse-ansi --plus-emph-style --plus-empty-line-marker-style --plus-non-emph-style --plus-style --raw --relative-paths --right-arrow --show-colors --show-config --show-syntax-themes --show-themes --side-by-side --syntax-theme --tabs --true-color --whitespace-error-style --width --word-diff-regex --wrap-left-symbol --wrap-max-lines --wrap-right-percent --wrap-right-prefix-symbol --wrap-right-symbol --zero-style --24-bit-color --help --version [MINUS_FILE] [PLUS_FILE]"
---
>             opts="-n -s -w -h -V --blame-code-style --blame-format --blame-palette --blame-separator-format --blame-separator-style --blame-timestamp-format --blame-timestamp-output-format --color-only --config --commit-decoration-style --commit-regex --commit-style --dark --default-language --diff-highlight --diff-so-fancy --diff-stat-align-width --features --file-added-label --file-copied-label --file-decoration-style --file-modified-label --file-removed-label --file-renamed-label --file-style --file-transformation --generate-completion --grep-context-line-style --grep-file-style --grep-header-decoration-style --grep-header-file-style --grep-line-number-style --grep-output-type --grep-match-line-style --grep-match-word-style --grep-separator-symbol --hunk-header-decoration-style --hunk-header-file-style --hunk-header-line-number-style --hunk-header-style --hunk-label --hyperlinks --hyperlinks-commit-link-format --hyperlinks-file-link-format --inline-hint-style --inspect-raw-lines --keep-plus-minus-markers --light --line-buffer-size --line-fill-method --line-numbers --line-numbers-left-format --line-numbers-left-style --line-numbers-minus-style --line-numbers-plus-style --line-numbers-right-format --line-numbers-right-style --line-numbers-zero-style --list-languages --list-syntax-themes --map-styles --max-line-distance --max-line-length --merge-conflict-begin-symbol --merge-conflict-end-symbol --merge-conflict-ours-diff-header-decoration-style --merge-conflict-ours-diff-header-style --merge-conflict-theirs-diff-header-decoration-style --merge-conflict-theirs-diff-header-style --minus-empty-line-marker-style --minus-emph-style --minus-non-emph-style --minus-style --navigate --navigate-regex --no-gitconfig --pager --paging --parse-ansi --plus-emph-style --plus-empty-line-marker-style --plus-non-emph-style --plus-style --raw --relative-paths --right-arrow --show-colors --show-config --show-syntax-themes --show-themes --side-by-side --syntax-theme --tabs --true-color --whitespace-error-style --width --word-diff-regex --wrap-left-symbol --wrap-max-lines --wrap-right-percent --wrap-right-prefix-symbol --wrap-right-symbol --zero-style --24-bit-color --help --version [MINUS_FILE] [PLUS_FILE]"
76,87d75
<                 --detect-dark-light)
<                     COMPREPLY=($(compgen -W "auto always never" -- "${cur}"))
<                     return 0
<                     ;;
<                 --diff-args)
<                     COMPREPLY=($(compgen -f "${cur}"))
<                     return 0
<                     ;;
<                 -@)
<                     COMPREPLY=($(compgen -f "${cur}"))
<                     return 0
<                     ;;
248,251d235
<                 --max-syntax-highlighting-length)
<                     COMPREPLY=($(compgen -f "${cur}"))
<                     return 0
<                     ;;
394,396c378,379
< if [[ "${BASH_VERSINFO[0]}" -eq 4 && "${BASH_VERSINFO[1]}" -ge 4 || "${BASH_VERSINFO[0]}" -gt 4 ]]; then
<     complete -F _delta -o nosort -o bashdefault -o default delta
< else
---
> # nosort isn't supported for bash less than < 4.4
> if [[ ${BASH_VERSINFO[0]} -lt 4 || ( ${BASH_VERSINFO[0]} -eq 4 && ${BASH_VERSINFO[1]} -lt 4 ) ]]; then
397a381,382
> else
>     complete -F _delta -o bashdefault -o default -o nosort delta 

delta.fish.diff

13,14d12
< complete -c delta -l detect-dark-light -d 'Detect whether or not the terminal is dark or light by querying for its colors' -r -f -a "{auto	'Only query the terminal for its colors if the output is not redirected',always	'Always query the terminal for its colors',never	'Never query the terminal for its colors'}"
< complete -c delta -s @ -l diff-args -d 'Extra arguments to pass to `git diff` when using delta to diff two files' -r
45c43
< complete -c delta -l line-fill-method -d 'Line-fill method in side-by-side mode' -r -f -a "{ansi	'',spaces	''}"
---
> complete -c delta -l line-fill-method -d 'Line-fill method in side-by-side mode' -r -f -a "{ansi spaces	''}"
55d52
< complete -c delta -l max-syntax-highlighting-length -d 'Stop syntax highlighting lines after this many characters' -r

delta.zsh.diff

30,34d29
< '--detect-dark-light=[Detect whether or not the terminal is dark or light by querying for its colors]:DETECT_DARK_LIGHT:((auto\:"Only query the terminal for its colors if the output is not redirected"
< always\:"Always query the terminal for its colors"
< never\:"Never query the terminal for its colors"))' \
< '-@+[Extra arguments to pass to \`git diff\` when using delta to diff two files]:STRING: ' \
< '--diff-args=[Extra arguments to pass to \`git diff\` when using delta to diff two files]:STRING: ' \
75d69
< '--max-syntax-highlighting-length=[Stop syntax highlighting lines after this many characters]:N: ' \
135,136c129,130
< '::minus_file -- First file to be compared when delta is being used to diff two files:_files' \
< '::plus_file -- Second file to be compared when delta is being used to diff two files:_files' \
---
> '::minus_file -- First file to be compared when delta is being used in diff mode:_files' \
> '::plus_file -- Second file to be compared when delta is being used in diff mode:_files' \