Unlike some implementations of regular expression engines, Vim's doesn't seem to support that notation (
[\s\w]) in collections. One can use POSIX character class expressions, though.
[:blank:] is the same as
[:space:] matches a greater number of whitespace characters than
\s does, and seems to be equivalent to
\w, but does not match the underscore (
So the collection you wanted could be written as
I haven't verified this by testing, but it is documented in
:h /character-classes, and
Portability note: In other regex engines,
\s is typically the same as
\_s) is in Vim.