Formatter drops a comment before the spread of a list pattern like list{/* c */ ...r} #9123

Formatting drops a comment written before the spread of a list pattern that has no other items.

let f = x =>
  switch x {
  | list{/* d */ ...r} => r
  }

bsc -format (master at 3562ce6) prints:

let f = x =>
  switch x {
  | r => r
  }

The comment /* d */ is gone. list{...r} parses to the pattern r itself, so the printer prints r, and the comment attached to the spread is never printed. The expression list{/* h */ ...xs} keeps its comment (/* h */ xs), and list{a, /* e */ ...r} keeps it too (with #9119).

Found while working on #9107; #9119 does not change this case.

🤖 Generated with Claude Code