patch 9.0.1958: cannot complete option values Commit: https://github.com/vim/vim/commit/900894b09a95398dfc75599e9f0aa2ea25723384 Author: Yee Cheng Chin <ychin.git@gmail.com> Date: Fri Sep 29 20:42:32 2023 +0200 patch 9.0.1958: cannot complete option values Problem: cannot complete option values Solution: Add completion functions for several options Add cmdline tab-completion for setting string options Add tab-completion for setting string options on the cmdline using `:set=` (along with `:set+=` and `:set-=`). The existing tab completion for setting options currently only works when nothing is typed yet, and it only fills in with the existing value, e.g. when the user does `:set diffopt=<Tab>` it will be completed to `set diffopt=internal,filler,closeoff` and nothing else. This isn't too useful as a user usually wants auto-complete to suggest all the possible values, such as 'iblank', or 'algorithm:patience'. For set= and set+=, this adds a new optional callback function for each option that can be invoked when doing completion. This allows for each option to have control over how completion works. For example, in 'diffopt', it will suggest the default enumeration, but if `algorithm:` is selected, it will further suggest different algorithm types like 'meyers' and 'patience'. When using set=, the existing option value will be filled in as the first choice to preserve the existing behavior. When using set+= this won't happen as it doesn't make sense. For flag list options (e.g. 'mouse' and 'guioptions'), completion will take into account existing typed values (and in the case of set+=, the existing option value) to make sure it doesn't suggest duplicates. For set-=, there is a new `ExpandSettingSubtract` function which will handle flag list and comma-separated options smartly, by only suggesting values that currently exist in the option. Note that Vim has some existing code that adds special handling for 'filetype', 'syntax', and misc dir options like 'backupdir'. This change preserves them as they already work, instead of converting to the new callback API for each option. closes: #13182 Signed-off-by: Christian Brabandt <cb@256bit.org> Co-authored-by: Yee Cheng Chin <ychin.git@gmail.com>