%r{} delimiter

[1] pry(main)> rgx = %r{
[1] pry(main)*  . # match any char; this comment contains an end brace }
=> /
 . # match any char; this comment contains an end brace /
[2] pry(main)> }x
SyntaxError: unexpected '}', expecting $end

default regexp delimiter

# syntax error on extended regex when delimiter is present in comments
rgx = /
 . # match any char; this comment contains a slash /
/x

# syntax error before we reach here

'foo'.match rgx  # expected #<MatchData "f">