((?>[^()]+)|\([^()]*\))+ ((abc(ade)ufh()()x y $& abc(ade)ufh()()x
(?<=x+)y - c - Variable length lookbehind not implemented
a{37,17} - c - Can't do {n,m} with n > m
+a{37,0} - c - Can't do {n,m} with n > m
\Z a\nb\n y $-[0] 3
\z a\nb\n y $-[0] 4
$ a\nb\n y $-[0] 3
/\d+$ \n/ix >10\n y $& 10
/>\d\d$ \n/ix >10\n y $& >10
/>\d+$ \n/x >10\n y $& >10
+
+# Two regressions in 5.8.x (only) introduced by change 30638
+# Simplification of the test failure in XML::LibXML::Simple:
+/^\s*i.*?o\s*$/s io\n io y - -
+# As reported in #59168 by Father Chrysostomos:
+/(.*?)a(?!(a+)b\2c)/ baaabaac y $&-$1 baa-ba
+# [perl #60344] Regex lookbehind failure after an (if)then|else in perl 5.10
+/\A(?(?=db2)db2|\D+)(?<!processed)\.csv\z/xms sql_processed.csv n - -
+/\N{U+0100}/ \x{100} y $& \x{100} # Bug #59328
+[\s][\S] \x{a0}\x{a0} nT - - # TODO Unicode complements should not match same character
+
+# was generating malformed utf8
+'[\x{100}\xff]'i \x{ff} y $& \x{ff}
+
+((??{ "(?:|)" }))\s C\x20 y - -