fish-shell/init/completions/diff.fish

# Completions for diff
complete -c diff -s i -l ignore-case -d "Ignore case differences"
complete -c diff -l ignore-file-name-case -d "Ignore case when comparing file names"
complete -c diff -l no-ignore-file-name-case -d "Consider case when comparing file names"
complete -c diff -s E -l ignore-tab-expansion -d "Ignore changes due to tab expansion"
complete -c diff -s b -l ignore-space-change -d "Ignore changes in the amount of white space"
complete -c diff -s w -l ignore-all-space -d "Ignore all white space"
complete -c diff -s B -l ignore-blank-lines -d "Ignore changes whose lines are all blank"
complete -c diff -s I -l ignore-matching-lines -x -d "Ignore changes whose lines match the RE"
complete -c diff -s a -l text -d "Treat all files as text"
complete -c diff -s r -l recursive -d "Recursively compare subdirectories"
complete -c diff -s N -l new-file -d "Treat absent files as empty"
complete -c diff -s C -l context -x -d "Output NUM lines of copied context"
complete -c diff -s c -d "Output 3 lines of copied context"
complete -c diff -s U -l unified -x -d "Output NUM lines of unified context"
complete -c diff -s u -d "Output 3 lines of unified context"
complete -c diff -s q -l brief -d "Output only whether the files differ"
complete -c diff -l normal -d "Output a normal diff"
complete -c diff -s y -l side-by-side -d "Output in two columns"
complete -c diff -s W -l width -x -d "Output at most NUM print columns"
complete -c diff -s d -l minimal -d "Try to find a smaller set of changes"
complete -c diff -l from-file -r -d "Compare FILE1 to all operands"
complete -c diff -l to-file -r -d "Compare FILE2 to all operands"
complete -c diff -s l -l paginate -d "Pass the output through 'pr'"
complete -c diff -s v -l version -d "Output version info"
complete -c diff -l help -d "Output usage information"