+ '/[a\fb]/' => "",
+ => 'Literal vertical space in [] is illegal except under /x {#} m/[a\f{#}b]/',
+ '/:{4,a}/' => 'Unescaped left brace in regex is passed through {#} m/:{{#}4,a}/',
+ => 'Unescaped left brace in regex is illegal here {#} m/:{{#}4,a}/',
+ '/xa{3\,4}y/' => 'Unescaped left brace in regex is passed through {#} m/xa{{#}3\,4}y/',
+ => 'Unescaped left brace in regex is illegal here {#} m/xa{{#}3\,4}y/',
+ '/\\${[^\\}]*}/' => 'Unescaped left brace in regex is passed through {#} m/\\${{#}[^\\}]*}/',
+ => 'Unescaped left brace in regex is illegal here {#} m/\\${{#}[^\\}]*}/',
+ '/.{/' => 'Unescaped left brace in regex is passed through {#} m/.{{#}/',
+ => 'Unescaped left brace in regex is illegal here {#} m/.{{#}/',
+ '/[x]{/' => 'Unescaped left brace in regex is passed through {#} m/[x]{{#}/',
+ => 'Unescaped left brace in regex is illegal here {#} m/[x]{{#}/',
+ '/\p{Latin}{/' => 'Unescaped left brace in regex is passed through {#} m/\p{Latin}{{#}/',
+ => 'Unescaped left brace in regex is illegal here {#} m/\p{Latin}{{#}/',