fix(comment): fall back to using trimmed comment markers (#28938)

Problem: Currently comment detection, addition, and removal are done
  by matching 'commentstring' exactly. This has the downside when users
  want to add comment markers with space (like with `-- %s`
  commentstring) but also be able to uncomment lines that do not contain
  space (like `--aaa`).

Solution: Use the following approach:
  - Line is commented if it matches 'commentstring' with trimmed parts.
  - Adding comment is 100% relying on 'commentstring' parts (as is now).
  - Removing comment is first trying exact 'commentstring' parts with
    fallback on trying its trimmed parts.

1 files changed, 4 insertions, 0 deletions

diff --git a/runtime/doc/various.txt b/runtime/doc/various.txt
index d41bdb5b00..662be4a7a2 100644
--- a/runtime/doc/various.txt
+++ b/runtime/doc/various.txt
@@ -579,6 +579,10 @@ Acting on multiple lines behaves as follows:
   transformed to empty comments (e.g. `/**/`). Comment markers are aligned to
   the least indented line.
 
+Matching 'commentstring' does not account for whitespace in comment markers.
+Removing comment markers is first attempted exactly, with fallback to using
+markers trimmed from whitespace.
+
 If the filetype of the buffer is associated with a language for which a
 |treesitter| parser is installed, then |vim.filetype.get_option()| is called
 to look up the value of 'commentstring' corresponding to the cursor position.