abc abc y $& abc
+abc abc y $-[0] 0
+abc abc y $+[0] 3
abc xbc n - -
abc axc n - -
abc abx n - -
abc xabcy y $& abc
+abc xabcy y $-[0] 1
+abc xabcy y $+[0] 4
abc ababc y $& abc
+abc ababc y $-[0] 2
+abc ababc y $+[0] 5
ab*c abc y $& abc
+ab*c abc y $-[0] 0
+ab*c abc y $+[0] 3
ab*bc abc y $& abc
+ab*bc abc y $-[0] 0
+ab*bc abc y $+[0] 3
ab*bc abbc y $& abbc
+ab*bc abbc y $-[0] 0
+ab*bc abbc y $+[0] 4
ab*bc abbbbc y $& abbbbc
+ab*bc abbbbc y $-[0] 0
+ab*bc abbbbc y $+[0] 6
.{1} abbbbc y $& a
+.{1} abbbbc y $-[0] 0
+.{1} abbbbc y $+[0] 1
.{3,4} abbbbc y $& abbb
+.{3,4} abbbbc y $-[0] 0
+.{3,4} abbbbc y $+[0] 4
ab{0,}bc abbbbc y $& abbbbc
+ab{0,}bc abbbbc y $-[0] 0
+ab{0,}bc abbbbc y $+[0] 6
ab+bc abbc y $& abbc
+ab+bc abbc y $-[0] 0
+ab+bc abbc y $+[0] 4
ab+bc abc n - -
ab+bc abq n - -
ab{1,}bc abq n - -
ab+bc abbbbc y $& abbbbc
+ab+bc abbbbc y $-[0] 0
+ab+bc abbbbc y $+[0] 6
ab{1,}bc abbbbc y $& abbbbc
+ab{1,}bc abbbbc y $-[0] 0
+ab{1,}bc abbbbc y $+[0] 6
ab{1,3}bc abbbbc y $& abbbbc
+ab{1,3}bc abbbbc y $-[0] 0
+ab{1,3}bc abbbbc y $+[0] 6
ab{3,4}bc abbbbc y $& abbbbc
+ab{3,4}bc abbbbc y $-[0] 0
+ab{3,4}bc abbbbc y $+[0] 6
ab{4,5}bc abbbbc n - -
ab?bc abbc y $& abbc
ab?bc abc y $& abc
a.*c axyzd n - -
a[bc]d abc n - -
a[bc]d abd y $& abd
+a[b]d abd y $& abd
+[a][b][d] abd y $& abd
+.[b]. abd y $& abd
+.[b]. aBd n - -
+(?i:.[b].) abd y $& abd
a[b-d]e abd n - -
a[b-d]e ace y $& ace
a[b-d] aac y $& ac
a[-b] a- y $& a-
a[b-] a- y $& a-
-a[b-a] - c - /a[b-a]/: invalid [] range "b-a" in regexp
-a[]b - c - /a[]b/: unmatched [] in regexp
-a[ - c - /a[/: unmatched [] in regexp
+a[b-a] - c - Invalid [] range "b-a"
+a[]b - c - Unmatched [
+a[ - c - Unmatched [
a] a] y $& a]
a[]]b a]b y $& a]b
a[^bc]d aed y $& aed
\Ba\B -a n - -
\Ba\B -a- n - -
\By\b xy y - -
+\By\b xy y $-[0] 1
+\By\b xy y $+[0] 2
+\By\b xy y - -
\by\B yz y - -
\By\B xyz y - -
\w a y - -
ab|cd abc y $& ab
ab|cd abcd y $& ab
()ef def y $&-$1 ef-
-*a - c - /*a/: ?+*{} follows nothing in regexp
-(*)b - c - /(*)b/: ?+*{} follows nothing in regexp
+()ef def y $-[0] 1
+()ef def y $+[0] 3
+()ef def y $-[1] 1
+()ef def y $+[1] 1
+*a - c - Quantifier follows nothing
+(*)b - c - Quantifier follows nothing
$b b n - -
a\ - c - Search pattern not terminated
a\(b a(b y $&-$1 a(b-
a\(*b ab y $& ab
a\(*b a((b y $& a((b
a\\b a\b y $& a\b
-abc) - c - /abc)/: unmatched () in regexp
-(abc - c - /(abc/: unmatched () in regexp
+abc) - c - Unmatched )
+(abc - c - Unmatched (
((a)) abc y $&-$1-$2 a-a-a
+((a)) abc y $-[0]-$-[1]-$-[2] 0-0-0
+((a)) abc y $+[0]-$+[1]-$+[2] 1-1-1
+((a)) abc b @- 0 0 0
+((a)) abc b @+ 1 1 1
(a)b(c) abc y $&-$1-$2 abc-a-c
+(a)b(c) abc y $-[0]-$-[1]-$-[2] 0-0-2
+(a)b(c) abc y $+[0]-$+[1]-$+[2] 3-1-3
a+b+c aabbabc y $& abc
a{1,}b{1,}c aabbabc y $& abc
-a** - c - /a**/: nested *?+ in regexp
+a** - c - Nested quantifiers
a.+?c abcabc y $& abc
(a+|b)* ab y $&-$1 ab-b
+(a+|b)* ab y $-[0] 0
+(a+|b)* ab y $+[0] 2
+(a+|b)* ab y $-[1] 1
+(a+|b)* ab y $+[1] 2
(a+|b){0,} ab y $&-$1 ab-b
(a+|b)+ ab y $&-$1 ab-b
(a+|b){1,} ab y $&-$1 ab-b
(a+|b)? ab y $&-$1 a-a
(a+|b){0,1} ab y $&-$1 a-a
-)( - c - /)(/: unmatched () in regexp
+)( - c - Unmatched )
[^ab]* cde y $& cde
abc n - -
a* y $&
([abc])*bcd abcd y $&-$1 abcd-a
a|b|c|d|e e y $& e
(a|b|c|d|e)f ef y $&-$1 ef-e
+(a|b|c|d|e)f ef y $-[0] 0
+(a|b|c|d|e)f ef y $+[0] 2
+(a|b|c|d|e)f ef y $-[1] 0
+(a|b|c|d|e)f ef y $+[1] 1
abcd*efg abcdefg y $& abcdefg
ab* xabyabbbz y $& ab
ab* xayabbbz y $& a
(ab|ab*)bc abc y $&-$1 abc-a
a([bc]*)c* abc y $&-$1 abc-bc
a([bc]*)(c*d) abcd y $&-$1-$2 abcd-bc-d
+a([bc]*)(c*d) abcd y $-[0] 0
+a([bc]*)(c*d) abcd y $+[0] 4
+a([bc]*)(c*d) abcd y $-[1] 1
+a([bc]*)(c*d) abcd y $+[1] 3
+a([bc]*)(c*d) abcd y $-[2] 3
+a([bc]*)(c*d) abcd y $+[2] 4
a([bc]+)(c*d) abcd y $&-$1-$2 abcd-bc-d
a([bc]*)(c+d) abcd y $&-$1-$2 abcd-b-cd
+a([bc]*)(c+d) abcd y $-[0] 0
+a([bc]*)(c+d) abcd y $+[0] 4
+a([bc]*)(c+d) abcd y $-[1] 1
+a([bc]*)(c+d) abcd y $+[1] 2
+a([bc]*)(c+d) abcd y $-[2] 2
+a([bc]*)(c+d) abcd y $+[2] 4
a[bcd]*dcdcde adcdcde y $& adcdcde
a[bcd]+dcdcde adcdcde n - -
(ab|a)b*c abc y $&-$1 abc-ab
+(ab|a)b*c abc y $-[0] 0
+(ab|a)b*c abc y $+[0] 3
+(ab|a)b*c abc y $-[1] 0
+(ab|a)b*c abc y $+[1] 2
((a)(b)c)(d) abcd y $1-$2-$3-$4 abc-a-b-d
+((a)(b)c)(d) abcd y $-[0] 0
+((a)(b)c)(d) abcd y $+[0] 4
+((a)(b)c)(d) abcd y $-[1] 0
+((a)(b)c)(d) abcd y $+[1] 3
+((a)(b)c)(d) abcd y $-[2] 0
+((a)(b)c)(d) abcd y $+[2] 1
+((a)(b)c)(d) abcd y $-[3] 1
+((a)(b)c)(d) abcd y $+[3] 2
+((a)(b)c)(d) abcd y $-[4] 3
+((a)(b)c)(d) abcd y $+[4] 4
[a-zA-Z_][a-zA-Z0-9_]* alpha y $& alpha
^a(bc+|b[eh])g|.h$ abh y $&-$1 bh-
(bc+d$|ef*g.|h?i(j|k)) effgz y $&-$1-$2 effgz-effgz-
(bc+d$|ef*g.|h?i(j|k)) bcdd n - -
(bc+d$|ef*g.|h?i(j|k)) reffgz y $&-$1-$2 effgz-effgz-
((((((((((a)))))))))) a y $10 a
+((((((((((a)))))))))) a y $-[0] 0
+((((((((((a)))))))))) a y $+[0] 1
+((((((((((a)))))))))) a y $-[10] 0
+((((((((((a)))))))))) a y $+[10] 1
((((((((((a))))))))))\10 aa y $& aa
((((((((((a))))))))))${bang} aa n - -
((((((((((a))))))))))${bang} a! y $& a!
a[-]?c ac y $& ac
(abc)\1 abcabc y $1 abc
([a-c]*)\1 abcabc y $1 abc
-\1 - c - /\1/: reference to nonexistent group
-\2 - c - /\2/: reference to nonexistent group
+\1 - c - Reference to nonexistent group
+\2 - c - Reference to nonexistent group
(a)|\1 a y - -
(a)|\1 x n - -
-(a)|\2 - c - /(a)|\2/: reference to nonexistent group
+(a)|\2 - c - Reference to nonexistent group
(([a-c])b*?\2)* ababbbcbc y $&-$1-$2 ababb-bb-b
(([a-c])b*?\2){3} ababbbcbc y $&-$1-$2 ababbbcbc-cbc-c
((\3|b)\2(a)x)+ aaxabxbaxbbx n - -
((\3|b)\2(a)x)+ aaaxabaxbaaxbbax y $&-$1-$2-$3 bbax-bbax-b-a
((\3|b)\2(a)){2,} bbaababbabaaaaabbaaaabba y $&-$1-$2-$3 bbaaaabba-bba-b-a
+(a)|(b) b y $-[0] 0
+(a)|(b) b y $+[0] 1
+(a)|(b) b y x$-[1] x
+(a)|(b) b y x$+[1] x
+(a)|(b) b y $-[2] 0
+(a)|(b) b y $+[2] 1
'abc'i ABC y $& ABC
'abc'i XBC n - -
'abc'i AXC n - -
'a[b-d]'i AAC y $& AC
'a[-b]'i A- y $& A-
'a[b-]'i A- y $& A-
-'a[b-a]'i - c - /a[b-a]/: invalid [] range "b-a" in regexp
-'a[]b'i - c - /a[]b/: unmatched [] in regexp
-'a['i - c - /a[/: unmatched [] in regexp
+'a[b-a]'i - c - Invalid [] range "b-a"
+'a[]b'i - c - Unmatched [
+'a['i - c - Unmatched [
'a]'i A] y $& A]
'a[]]b'i A]B y $& A]B
'a[^bc]d'i AED y $& AED
'ab|cd'i ABC y $& AB
'ab|cd'i ABCD y $& AB
'()ef'i DEF y $&-$1 EF-
-'*a'i - c - /*a/: ?+*{} follows nothing in regexp
-'(*)b'i - c - /(*)b/: ?+*{} follows nothing in regexp
+'*a'i - c - Quantifier follows nothing
+'(*)b'i - c - Quantifier follows nothing
'$b'i B n - -
'a\'i - c - Search pattern not terminated
'a\(b'i A(B y $&-$1 A(B-
'a\(*b'i AB y $& AB
'a\(*b'i A((B y $& A((B
'a\\b'i A\B y $& A\B
-'abc)'i - c - /abc)/: unmatched () in regexp
-'(abc'i - c - /(abc/: unmatched () in regexp
+'abc)'i - c - Unmatched )
+'(abc'i - c - Unmatched (
'((a))'i ABC y $&-$1-$2 A-A-A
'(a)b(c)'i ABC y $&-$1-$2 ABC-A-C
'a+b+c'i AABBABC y $& ABC
'a{1,}b{1,}c'i AABBABC y $& ABC
-'a**'i - c - /a**/: nested *?+ in regexp
+'a**'i - c - Nested quantifiers
'a.+?c'i ABCABC y $& ABC
'a.*?c'i ABCABC y $& ABC
'a.{0,5}?c'i ABCABC y $& ABC
'(a+|b)?'i AB y $&-$1 A-A
'(a+|b){0,1}'i AB y $&-$1 A-A
'(a+|b){0,1}?'i AB y $&-$1 -
-')('i - c - /)(/: unmatched () in regexp
+')('i - c - Unmatched )
'[^ab]*'i CDE y $& CDE
'abc'i n - -
'a*'i y $&
a(?:b|c|d){4,5}(.) acdbcdbe y $1 b
a(?:b|c|d){4,5}?(.) acdbcdbe y $1 d
((foo)|(bar))* foobar y $1-$2-$3 bar-foo-bar
-:(?: - c - /(?/: Sequence (? incomplete
+:(?: - c - Sequence (? incomplete
a(?:b|c|d){6,7}(.) acdbcdbe y $1 e
a(?:b|c|d){6,7}?(.) acdbcdbe y $1 e
a(?:b|c|d){5,6}(.) acdbcdbe y $1 e
(?<!c)b cb n - -
(?<!c)b b y - -
(?<!c)b b y $& b
-(?<%)b - c - /(?<%)b/: Sequence (?%...) not recognized
+(?<%)b - c - Sequence (?<%...) not recognized
(?:..)*a aba y $& aba
(?:..)*?a aba y $& a
^(?:b|a(?=(.)))*\1 abc y $& ab
'(ab)\d\1'i ab4Ab y $1 ab
foo\w*\d{4}baz foobar1234baz y $& foobar1234baz
a(?{})b cabd y $& ab
-a(?{)b - c - /a(?{)b/: Sequence (?{...}) not terminated or not {}-balanced
-a(?{{})b - c - /a(?{{})b/: Sequence (?{...}) not terminated or not {}-balanced
-a(?{}})b - c - /a(?{}})b/: Sequence (?{...}) not terminated or not {}-balanced
-a(?{"{"})b - c - /a(?{"{"})b/: Sequence (?{...}) not terminated or not {}-balanced
+a(?{)b - c - Sequence (?{...}) not terminated or not {}-balanced
+a(?{{})b - c - Sequence (?{...}) not terminated or not {}-balanced
+a(?{}})b - c -
+a(?{"{"})b - c - Sequence (?{...}) not terminated or not {}-balanced
a(?{"\{"})b cabd y $& ab
a(?{"{"}})b - c - Unmatched right curly bracket
a(?{$bl="\{"}).b caxbd y $bl {
^(\(+)?blah(?(1)(\)))$ blah y ($2) ()
^(\(+)?blah(?(1)(\)))$ blah) n - -
^(\(+)?blah(?(1)(\)))$ (blah n - -
-(?(1?)a|b) a c - /(?(1?)a|b)/: Switch (?(number? not recognized
-(?(1)a|b|c) a c - /(?(1)a|b|c)/: Switch (?(condition)... contains too many branches
+(?(1?)a|b) a c - Switch condition not recognized
+(?(1)a|b|c) a c - Switch (?(condition)... contains too many branches
(?(?{0})a|b) a n - -
(?(?{0})b|a) a y $& a
(?(?{1})b|a) a n - -
([[:]+) a:[b]: y $1 :[
([[=]+) a=[b]= y $1 =[
([[.]+) a.[b]. y $1 .[
-[a[:xyz: - c - /[a[:xyz:/: unmatched [] in regexp
-[a[:xyz:] - c - Character class [:xyz:] unknown
+[a[:xyz: - c - Unmatched [
+[a[:xyz:] - c - POSIX class [:xyz:] unknown
[a[:]b[:c] abc y $& abc
-([a[:xyz:]b]+) pbaq c - Character class [:xyz:] unknown
+([a[:xyz:]b]+) pbaq c - POSIX class [:xyz:] unknown
[a[:]b[:c] abc y $& abc
([[:alpha:]]+) ABcd01Xy__-- ${nulnul}${ffff} y $1 ABcd
([[:alnum:]]+) ABcd01Xy__-- ${nulnul}${ffff} y $1 ABcd01Xy
([[:^word:]]+) ABcd01Xy__-- ${nulnul}${ffff} y $1 -- ${nulnul}${ffff}
([[:^upper:]]+) ABcd01Xy__-- ${nulnul}${ffff} y $1 cd01
([[:^xdigit:]]+) ABcd01Xy__-- ${nulnul}${ffff} y $1 Xy__-- ${nulnul}${ffff}
-[[:foo:]] - c - Character class [:foo:] unknown
-[[:^foo:]] - c - Character class [:^foo:] unknown
+[[:foo:]] - c - POSIX class [:foo:] unknown
+[[:^foo:]] - c - POSIX class [:^foo:] unknown
((?>a+)b) aaab y $1 aaab
(?>(a+))b aaab y $1 aaa
((?>[^()]+)|\([^()]*\))+ ((abc(ade)ufh()()x y $& abc(ade)ufh()()x
-(?<=x+)y - c - /(?<=x+)y/: variable length lookbehind not implemented
-a{37,17} - c - /a{37,17}/: Can't do {n,m} with n > m
+(?<=x+)y - c - Variable length lookbehind not implemented
+a{37,17} - 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
a\Z b\na y $-[0] 2
a\z b\na y $-[0] 2
a$ b\na y $-[0] 2
-'a\Z'm a\nb\n bn - -
+'a\Z'm a\nb\n n - -
'a\z'm a\nb\n n - -
'a$'m a\nb\n y $-[0] 0
'a\Z'm b\na\n y $-[0] 2
aa\Z b\naa y $-[0] 2
aa\z b\naa y $-[0] 2
aa$ b\naa y $-[0] 2
-'aa\Z'm aa\nb\n bn - -
+'aa\Z'm aa\nb\n n - -
'aa\z'm aa\nb\n n - -
'aa$'m aa\nb\n y $-[0] 0
'aa\Z'm b\naa\n y $-[0] 2
ab\Z b\nab y $-[0] 2
ab\z b\nab y $-[0] 2
ab$ b\nab y $-[0] 2
-'ab\Z'm ab\nb\n bn - -
+'ab\Z'm ab\nb\n n - -
'ab\z'm ab\nb\n n - -
'ab$'m ab\nb\n y $-[0] 0
'ab\Z'm b\nab\n y $-[0] 2
abb\Z b\nabb y $-[0] 2
abb\z b\nabb y $-[0] 2
abb$ b\nabb y $-[0] 2
-'abb\Z'm abb\nb\n bn - -
+'abb\Z'm abb\nb\n n - -
'abb\z'm abb\nb\n n - -
'abb$'m abb\nb\n y $-[0] 0
'abb\Z'm b\nabb\n y $-[0] 2
^(.,){2}c a,b,c y $1 b,
^(?:[^,]*,){2}c a,b,c y - -
^([^,]*,){2}c a,b,c y $1 b,
+^([^,]*,){3}d aaa,b,c,d y $1 c,
+^([^,]*,){3,}d aaa,b,c,d y $1 c,
+^([^,]*,){0,3}d aaa,b,c,d y $1 c,
+^([^,]{1,3},){3}d aaa,b,c,d y $1 c,
+^([^,]{1,3},){3,}d aaa,b,c,d y $1 c,
+^([^,]{1,3},){0,3}d aaa,b,c,d y $1 c,
+^([^,]{1,},){3}d aaa,b,c,d y $1 c,
+^([^,]{1,},){3,}d aaa,b,c,d y $1 c,
+^([^,]{1,},){0,3}d aaa,b,c,d y $1 c,
+^([^,]{0,3},){3}d aaa,b,c,d y $1 c,
+^([^,]{0,3},){3,}d aaa,b,c,d y $1 c,
+^([^,]{0,3},){0,3}d aaa,b,c,d y $1 c,
(?i) y - -
'(?!\A)x'm a\nxb\n y - -
^(a(b)?)+$ aba y -$1-$2- -a--
'^.{9}abc.*\n'm 123\nabcabcabcabc\n y - -
^(a)?a$ a y -$1- --
^(a)?(?(1)a|b)+$ a n - -
+^(a\1?)(a\1?)(a\2?)(a\3?)$ aaaaaa y $1,$2,$3,$4 a,aa,a,aa
+^(a\1?){4}$ aaaaaa y $1 aa
+^(0+)?(?:x(1))? x1 y - -
+^([0-9a-fA-F]+)(?:x([0-9a-fA-F]+)?)(?:x([0-9a-fA-F]+))? 012cxx0190 y - -
+^(b+?|a){1,2}c bbbac y $1 a
+^(b+?|a){1,2}c bbbbac y $1 a
+\((\w\. \w+)\) cd. (A. Tw) y -$1- -A. Tw-
+((?:aaaa|bbbb)cccc)? aaaacccc y - -
+((?:aaaa|bbbb)cccc)? bbbbcccc y - -
+(a)?(a)+ a y $1:$2 :a -
+(ab)?(ab)+ ab y $1:$2 :ab -
+(abc)?(abc)+ abc y $1:$2 :abc -
+'b\s^'m a\nb\n n - -
+\ba a y - -
+^(a(??{"(?!)"})|(a)(?{1}))b ab y $2 a # [ID 20010811.006]
+ab(?i)cd AbCd n - - # [ID 20010809.023]
+ab(?i)cd abCd y - -
+(A|B)*(?(1)(CD)|(CD)) CD y $2-$3 -CD
+(A|B)*(?(1)(CD)|(CD)) ABCD y $2-$3 CD-
+(A|B)*?(?(1)(CD)|(CD)) CD y $2-$3 -CD # [ID 20010803.016]
+(A|B)*?(?(1)(CD)|(CD)) ABCD y $2-$3 CD-
+'^(o)(?!.*\1)'i Oo n - -
+(.*)\d+\1 abc12bc y $1 bc
+(?m:(foo\s*$)) foo\n bar y $1 foo
+(.*)c abcd y $1 ab
+(.*)(?=c) abcd y $1 ab
+(.*)(?=c)c abcd yB $1 ab
+(.*)(?=b|c) abcd y $1 ab
+(.*)(?=b|c)c abcd y $1 ab
+(.*)(?=c|b) abcd y $1 ab
+(.*)(?=c|b)c abcd y $1 ab
+(.*)(?=[bc]) abcd y $1 ab
+(.*)(?=[bc])c abcd yB $1 ab
+(.*)(?<=b) abcd y $1 ab
+(.*)(?<=b)c abcd y $1 ab
+(.*)(?<=b|c) abcd y $1 abc
+(.*)(?<=b|c)c abcd y $1 ab
+(.*)(?<=c|b) abcd y $1 abc
+(.*)(?<=c|b)c abcd y $1 ab
+(.*)(?<=[bc]) abcd y $1 abc
+(.*)(?<=[bc])c abcd y $1 ab
+(.*?)c abcd y $1 ab
+(.*?)(?=c) abcd y $1 ab
+(.*?)(?=c)c abcd yB $1 ab
+(.*?)(?=b|c) abcd y $1 a
+(.*?)(?=b|c)c abcd y $1 ab
+(.*?)(?=c|b) abcd y $1 a
+(.*?)(?=c|b)c abcd y $1 ab
+(.*?)(?=[bc]) abcd y $1 a
+(.*?)(?=[bc])c abcd yB $1 ab
+(.*?)(?<=b) abcd y $1 ab
+(.*?)(?<=b)c abcd y $1 ab
+(.*?)(?<=b|c) abcd y $1 ab
+(.*?)(?<=b|c)c abcd y $1 ab
+(.*?)(?<=c|b) abcd y $1 ab
+(.*?)(?<=c|b)c abcd y $1 ab
+(.*?)(?<=[bc]) abcd y $1 ab
+(.*?)(?<=[bc])c abcd y $1 ab
+2(]*)?$\1 2 y $& 2
+(??{}) x y - -
+a(b)?? abc y <$1> <> # undef [perl #16773]
+(\d{1,3}\.){3,} 128.134.142.8 y <$1> <142.> # [perl #18019]
+^.{3,4}(.+)\1\z foobarbar y $1 bar # 16 tests for [perl #23171]
+^(?:f|o|b){3,4}(.+)\1\z foobarbar y $1 bar
+^.{3,4}((?:b|a|r)+)\1\z foobarbar y $1 bar
+^(?:f|o|b){3,4}((?:b|a|r)+)\1\z foobarbar y $1 bar
+^.{3,4}(.+?)\1\z foobarbar y $1 bar
+^(?:f|o|b){3,4}(.+?)\1\z foobarbar y $1 bar
+^.{3,4}((?:b|a|r)+?)\1\z foobarbar y $1 bar
+^(?:f|o|b){3,4}((?:b|a|r)+?)\1\z foobarbar y $1 bar
+^.{2,3}?(.+)\1\z foobarbar y $1 bar
+^(?:f|o|b){2,3}?(.+)\1\z foobarbar y $1 bar
+^.{2,3}?((?:b|a|r)+)\1\z foobarbar y $1 bar
+^(?:f|o|b){2,3}?((?:b|a|r)+)\1\z foobarbar y $1 bar
+^.{2,3}?(.+?)\1\z foobarbar y $1 bar
+^(?:f|o|b){2,3}?(.+?)\1\z foobarbar y $1 bar
+^.{2,3}?((?:b|a|r)+?)\1\z foobarbar y $1 bar
+^(?:f|o|b){2,3}?((?:b|a|r)+?)\1\z foobarbar y $1 bar
+.*a(?!(b|cd)*e).*f ......abef n - - # [perl #23030]
+x(?# x c - Sequence (?#... not terminated
+:x(?#: x c - Sequence (?#... not terminated
+(WORDS|WORD)S WORDS y $1 WORD
+(X.|WORDS|X.|WORD)S WORDS y $1 WORD
+(WORDS|WORLD|WORD)S WORDS y $1 WORD
+(X.|WORDS|WORD|Y.)S WORDS y $1 WORD
+(foo|fool|x.|money|parted)$ fool y $1 fool
+(x.|foo|fool|x.|money|parted|y.)$ fool y $1 fool
+(foo|fool|money|parted)$ fool y $1 fool
+(foo|fool|x.|money|parted)$ fools n - -
+(x.|foo|fool|x.|money|parted|y.)$ fools n - -
+(foo|fool|money|parted)$ fools n - -
+(a|aa|aaa||aaaa|aaaaa|aaaaaa)(b|c) aaaaaaaaaaaaaaab y $1$2 aaaaaab
+(a|aa|aaa||aaaa|aaaaa|aaaaaa)(??{$1&&""})(b|c) aaaaaaaaaaaaaaab y $1$2 aaaaaab
+(a|aa|aaa|aaaa|aaaaa|aaaaaa)(??{$1&&"foo"})(b|c) aaaaaaaaaaaaaaab n - -
+^(a*?)(?!(aa|aaaa)*$) aaaaaaaaaaaaaaaaaaaa y $1 a # [perl #34195]
+^(a*?)(?!(aa|aaaa)*$)(?=a\z) aaaaaaaa y $1 aaaaaaa
+^(.)\s+.$(?(1)) A B y $1 A # [perl #37688]
+(?:r?)*?r|(.{2,4}) abcde y $1 abcd
+(?!)+?|(.{2,4}) abcde y $1 abcd
+^(a*?)(?!(a{6}|a{5})*$) aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa y $+[1] 12 # super-linear cache bug may return 18
+^((?>(?:aa)?b)?) aab y $1 aab
+^((?:aa)*)(?:X+((?:\d+|-)(?:X+(.+))?))?$ aaaaX5 y $1 aaaa
+X(A|B||C|D)Y XXXYYY y $& XY # Trie w/ NOTHING
+(?i:X([A]|[B]|y[Y]y|[D]|)Y) XXXYYYB y $& XY # Trie w/ NOTHING
+^([a]{1})*$ aa y $1 a