18 files changed, 815 insertions, 214 deletions
diff --git a/dist/B-Deparse/Deparse.pm b/dist/B-Deparse/Deparse.pm
index 296be02f84..054b919e38 100644
--- a/dist/B-Deparse/Deparse.pm
+++ b/dist/B-Deparse/Deparse.pm
@@ -20,7 +20,7 @@ use B qw(class main_root main_start main_cv svref_2object opnumber perlstring
          CVf_METHOD CVf_LVALUE
 	 PMf_KEEP PMf_GLOBAL PMf_CONTINUE PMf_EVAL PMf_ONCE
 	 PMf_MULTILINE PMf_SINGLELINE PMf_FOLD PMf_EXTENDED);
-$VERSION = "1.11";
+$VERSION = "1.12";
 use strict;
 use vars qw/$AUTOLOAD/;
 use warnings ();
@@ -1674,6 +1674,7 @@ my %feature_keywords = (
     break   => 'switch',
     evalbytes=>'evalbytes',
     __SUB__ => '__SUB__',
+   fc       => 'fc',
 );
 
 sub keyword {
@@ -2147,6 +2148,7 @@ sub pp_lcfirst { dq_unop(@_, "lcfirst") }
 sub pp_uc { dq_unop(@_, "uc") }
 sub pp_lc { dq_unop(@_, "lc") }
 sub pp_quotemeta { maybe_targmy(@_, \&dq_unop, "quotemeta") }
+sub pp_fc { dq_unop(@_, "fc") }
 
 sub loopex {
     my $self = shift;
@@ -4116,6 +4118,8 @@ sub dq {
 	return '\l' . $self->dq($op->first->sibling);
     } elsif ($type eq "quotemeta") {
 	return '\Q' . $self->dq($op->first->sibling) . '\E';
+    } elsif ($type eq "fc") {
+	return '\F' . $self->dq($op->first->sibling) . '\E';
     } elsif ($type eq "join") {
 	return $self->deparse($op->last, 26); # was join($", @ary)
     } else {
@@ -4437,6 +4441,8 @@ sub re_dq {
 	return '\l' . $self->re_dq($op->first->sibling, $extended);
     } elsif ($type eq "quotemeta") {
 	return '\Q' . $self->re_dq($op->first->sibling, $extended) . '\E';
+    } elsif ($type eq "fc") {
+	return '\F' . $self->re_dq($op->first->sibling, $extended) . '\E';
     } elsif ($type eq "join") {
 	return $self->deparse($op->last, 26); # was join($", @ary)
     } else {
@@ -4454,7 +4460,7 @@ sub pure_string {
     if ($type eq 'const' || $type eq 'av2arylen') {
 	return 1;
     }
-    elsif ($type =~ /^[ul]c(first)?$/ || $type eq 'quotemeta') {
+    elsif ($type =~ /^(?:[ul]c(first)?|fc)$/ || $type eq 'quotemeta') {
 	return $self->pure_string($op->first->sibling);
     }
     elsif ($type eq 'join') {
diff --git a/dist/B-Deparse/t/core.t b/dist/B-Deparse/t/core.t
index f5952af89c..62ff862e04 100644
--- a/dist/B-Deparse/t/core.t
+++ b/dist/B-Deparse/t/core.t
@@ -21,7 +21,7 @@ my @nary = (
      [qw( abs alarm break chr cos chop close chdir chomp chmod chown
           chroot caller continue die dump exp exit exec endgrent
           endpwent endnetent endhostent endservent
-          endprotoent evalbytes fork glob
+          endprotoent evalbytes fc fork glob
           getppid getpwent getprotoent gethostent getnetent getservent
           getgrent getlogin getc gmtime hex int lc log lstat length
           lcfirst localtime mkdir ord oct pop quotemeta ref rand
@@ -31,7 +31,7 @@ my @nary = (
  # unary
      [qw( abs alarm bless binmode chr cos chop close chdir chomp
           chmod chown chroot closedir die do dump exp exit exec
-          each evalbytes fileno getpgrp getpwnam getpwuid getpeername
+          each evalbytes fc fileno getpgrp getpwnam getpwuid getpeername
           getprotobyname getprotobynumber gethostbyname
           getnetbyname getsockname getgrnam getgrgid
           getc glob gmtime hex int join keys kill lc
diff --git a/dist/B-Deparse/t/deparse.t b/dist/B-Deparse/t/deparse.t
index 2831981de7..cae808c1d0 100644
--- a/dist/B-Deparse/t/deparse.t
+++ b/dist/B-Deparse/t/deparse.t
@@ -870,6 +870,7 @@ CORE::given ($x) {
 }
 CORE::evalbytes '';
 () = CORE::__SUB__;
+() = CORE::fc $x;
 ####
 # feature features when feature has been disabled by use VERSION
 use feature (sprintf(":%vd", $^V));
diff --git a/ext/Opcode/Opcode.pm b/ext/Opcode/Opcode.pm
index 91a7206ec7..a9d5ab2151 100644
--- a/ext/Opcode/Opcode.pm
+++ b/ext/Opcode/Opcode.pm
@@ -6,7 +6,7 @@ use strict;
 
 our($VERSION, @ISA, @EXPORT_OK);
 
-$VERSION = "1.22";
+$VERSION = "1.23";
 
 use Carp;
 use Exporter ();
@@ -325,7 +325,7 @@ invert_opset function.
 
     substr vec stringify study pos length index rindex ord chr
 
-    ucfirst lcfirst uc lc quotemeta trans transr chop schop chomp schomp
+    ucfirst lcfirst uc lc fc quotemeta trans transr chop schop chomp schomp
 
     match split qr
 
diff --git a/keywords.c b/keywords.c
index 169a41c411..23d550df83 100644
--- a/keywords.c
+++ b/keywords.c
@@ -51,7 +51,7 @@ Perl_keyword (pTHX_ const char *name, I32 len, bool all_keywords)
           goto unknown;
       }
 
-    case 2: /* 18 tokens of length 2 */
+    case 2: /* 19 tokens of length 2 */
       switch (name[0])
       {
         case 'd':
@@ -70,6 +70,14 @@ Perl_keyword (pTHX_ const char *name, I32 len, bool all_keywords)
 
           goto unknown;
 
+        case 'f':
+          if (name[1] == 'c')
+          {                                       /* fc               */
+            return (all_keywords || FEATURE_FC_IS_ENABLED ? -KEY_fc : 0);
+          }
+
+          goto unknown;
+
         case 'g':
           switch (name[1])
           {
@@ -3441,5 +3449,5 @@ unknown:
 }
 
 /* Generated from:
- * 29732a698b229f9e5f475fbb191f71c335c9e8d05b6168fe29e61c34c4f10bd2 regen/keywords.pl
+ * e5a540774760ea54c761ef17ee4a153cc264e9a700b817d561e390730c457406 regen/keywords.pl
  * ex: set ro: */
diff --git a/keywords.h b/keywords.h
index ea200fc31c..5ebde874ff 100644
--- a/keywords.h
+++ b/keywords.h
@@ -77,198 +77,199 @@
 #define KEY_exists		61
 #define KEY_exit		62
 #define KEY_exp			63
-#define KEY_fcntl		64
-#define KEY_fileno		65
-#define KEY_flock		66
-#define KEY_for			67
-#define KEY_foreach		68
-#define KEY_fork		69
-#define KEY_format		70
-#define KEY_formline		71
-#define KEY_ge			72
-#define KEY_getc		73
-#define KEY_getgrent		74
-#define KEY_getgrgid		75
-#define KEY_getgrnam		76
-#define KEY_gethostbyaddr	77
-#define KEY_gethostbyname	78
-#define KEY_gethostent		79
-#define KEY_getlogin		80
-#define KEY_getnetbyaddr	81
-#define KEY_getnetbyname	82
-#define KEY_getnetent		83
-#define KEY_getpeername		84
-#define KEY_getpgrp		85
-#define KEY_getppid		86
-#define KEY_getpriority		87
-#define KEY_getprotobyname	88
-#define KEY_getprotobynumber	89
-#define KEY_getprotoent		90
-#define KEY_getpwent		91
-#define KEY_getpwnam		92
-#define KEY_getpwuid		93
-#define KEY_getservbyname	94
-#define KEY_getservbyport	95
-#define KEY_getservent		96
-#define KEY_getsockname		97
-#define KEY_getsockopt		98
-#define KEY_given		99
-#define KEY_glob		100
-#define KEY_gmtime		101
-#define KEY_goto		102
-#define KEY_grep		103
-#define KEY_gt			104
-#define KEY_hex			105
-#define KEY_if			106
-#define KEY_index		107
-#define KEY_int			108
-#define KEY_ioctl		109
-#define KEY_join		110
-#define KEY_keys		111
-#define KEY_kill		112
-#define KEY_last		113
-#define KEY_lc			114
-#define KEY_lcfirst		115
-#define KEY_le			116
-#define KEY_length		117
-#define KEY_link		118
-#define KEY_listen		119
-#define KEY_local		120
-#define KEY_localtime		121
-#define KEY_lock		122
-#define KEY_log			123
-#define KEY_lstat		124
-#define KEY_lt			125
-#define KEY_m			126
-#define KEY_map			127
-#define KEY_mkdir		128
-#define KEY_msgctl		129
-#define KEY_msgget		130
-#define KEY_msgrcv		131
-#define KEY_msgsnd		132
-#define KEY_my			133
-#define KEY_ne			134
-#define KEY_next		135
-#define KEY_no			136
-#define KEY_not			137
-#define KEY_oct			138
-#define KEY_open		139
-#define KEY_opendir		140
-#define KEY_or			141
-#define KEY_ord			142
-#define KEY_our			143
-#define KEY_pack		144
-#define KEY_package		145
-#define KEY_pipe		146
-#define KEY_pop			147
-#define KEY_pos			148
-#define KEY_print		149
-#define KEY_printf		150
-#define KEY_prototype		151
-#define KEY_push		152
-#define KEY_q			153
-#define KEY_qq			154
-#define KEY_qr			155
-#define KEY_quotemeta		156
-#define KEY_qw			157
-#define KEY_qx			158
-#define KEY_rand		159
-#define KEY_read		160
-#define KEY_readdir		161
-#define KEY_readline		162
-#define KEY_readlink		163
-#define KEY_readpipe		164
-#define KEY_recv		165
-#define KEY_redo		166
-#define KEY_ref			167
-#define KEY_rename		168
-#define KEY_require		169
-#define KEY_reset		170
-#define KEY_return		171
-#define KEY_reverse		172
-#define KEY_rewinddir		173
-#define KEY_rindex		174
-#define KEY_rmdir		175
-#define KEY_s			176
-#define KEY_say			177
-#define KEY_scalar		178
-#define KEY_seek		179
-#define KEY_seekdir		180
-#define KEY_select		181
-#define KEY_semctl		182
-#define KEY_semget		183
-#define KEY_semop		184
-#define KEY_send		185
-#define KEY_setgrent		186
-#define KEY_sethostent		187
-#define KEY_setnetent		188
-#define KEY_setpgrp		189
-#define KEY_setpriority		190
-#define KEY_setprotoent		191
-#define KEY_setpwent		192
-#define KEY_setservent		193
-#define KEY_setsockopt		194
-#define KEY_shift		195
-#define KEY_shmctl		196
-#define KEY_shmget		197
-#define KEY_shmread		198
-#define KEY_shmwrite		199
-#define KEY_shutdown		200
-#define KEY_sin			201
-#define KEY_sleep		202
-#define KEY_socket		203
-#define KEY_socketpair		204
-#define KEY_sort		205
-#define KEY_splice		206
-#define KEY_split		207
-#define KEY_sprintf		208
-#define KEY_sqrt		209
-#define KEY_srand		210
-#define KEY_stat		211
-#define KEY_state		212
-#define KEY_study		213
-#define KEY_sub			214
-#define KEY_substr		215
-#define KEY_symlink		216
-#define KEY_syscall		217
-#define KEY_sysopen		218
-#define KEY_sysread		219
-#define KEY_sysseek		220
-#define KEY_system		221
-#define KEY_syswrite		222
-#define KEY_tell		223
-#define KEY_telldir		224
-#define KEY_tie			225
-#define KEY_tied		226
-#define KEY_time		227
-#define KEY_times		228
-#define KEY_tr			229
-#define KEY_truncate		230
-#define KEY_uc			231
-#define KEY_ucfirst		232
-#define KEY_umask		233
-#define KEY_undef		234
-#define KEY_unless		235
-#define KEY_unlink		236
-#define KEY_unpack		237
-#define KEY_unshift		238
-#define KEY_untie		239
-#define KEY_until		240
-#define KEY_use			241
-#define KEY_utime		242
-#define KEY_values		243
-#define KEY_vec			244
-#define KEY_wait		245
-#define KEY_waitpid		246
-#define KEY_wantarray		247
-#define KEY_warn		248
-#define KEY_when		249
-#define KEY_while		250
-#define KEY_write		251
-#define KEY_x			252
-#define KEY_xor			253
-#define KEY_y			254
+#define KEY_fc			64
+#define KEY_fcntl		65
+#define KEY_fileno		66
+#define KEY_flock		67
+#define KEY_for			68
+#define KEY_foreach		69
+#define KEY_fork		70
+#define KEY_format		71
+#define KEY_formline		72
+#define KEY_ge			73
+#define KEY_getc		74
+#define KEY_getgrent		75
+#define KEY_getgrgid		76
+#define KEY_getgrnam		77
+#define KEY_gethostbyaddr	78
+#define KEY_gethostbyname	79
+#define KEY_gethostent		80
+#define KEY_getlogin		81
+#define KEY_getnetbyaddr	82
+#define KEY_getnetbyname	83
+#define KEY_getnetent		84
+#define KEY_getpeername		85
+#define KEY_getpgrp		86
+#define KEY_getppid		87
+#define KEY_getpriority		88
+#define KEY_getprotobyname	89
+#define KEY_getprotobynumber	90
+#define KEY_getprotoent		91
+#define KEY_getpwent		92
+#define KEY_getpwnam		93
+#define KEY_getpwuid		94
+#define KEY_getservbyname	95
+#define KEY_getservbyport	96
+#define KEY_getservent		97
+#define KEY_getsockname		98
+#define KEY_getsockopt		99
+#define KEY_given		100
+#define KEY_glob		101
+#define KEY_gmtime		102
+#define KEY_goto		103
+#define KEY_grep		104
+#define KEY_gt			105
+#define KEY_hex			106
+#define KEY_if			107
+#define KEY_index		108
+#define KEY_int			109
+#define KEY_ioctl		110
+#define KEY_join		111
+#define KEY_keys		112
+#define KEY_kill		113
+#define KEY_last		114
+#define KEY_lc			115
+#define KEY_lcfirst		116
+#define KEY_le			117
+#define KEY_length		118
+#define KEY_link		119
+#define KEY_listen		120
+#define KEY_local		121
+#define KEY_localtime		122
+#define KEY_lock		123
+#define KEY_log			124
+#define KEY_lstat		125
+#define KEY_lt			126
+#define KEY_m			127
+#define KEY_map			128
+#define KEY_mkdir		129
+#define KEY_msgctl		130
+#define KEY_msgget		131
+#define KEY_msgrcv		132
+#define KEY_msgsnd		133
+#define KEY_my			134
+#define KEY_ne			135
+#define KEY_next		136
+#define KEY_no			137
+#define KEY_not			138
+#define KEY_oct			139
+#define KEY_open		140
+#define KEY_opendir		141
+#define KEY_or			142
+#define KEY_ord			143
+#define KEY_our			144
+#define KEY_pack		145
+#define KEY_package		146
+#define KEY_pipe		147
+#define KEY_pop			148
+#define KEY_pos			149
+#define KEY_print		150
+#define KEY_printf		151
+#define KEY_prototype		152
+#define KEY_push		153
+#define KEY_q			154
+#define KEY_qq			155
+#define KEY_qr			156
+#define KEY_quotemeta		157
+#define KEY_qw			158
+#define KEY_qx			159
+#define KEY_rand		160
+#define KEY_read		161
+#define KEY_readdir		162
+#define KEY_readline		163
+#define KEY_readlink		164
+#define KEY_readpipe		165
+#define KEY_recv		166
+#define KEY_redo		167
+#define KEY_ref			168
+#define KEY_rename		169
+#define KEY_require		170
+#define KEY_reset		171
+#define KEY_return		172
+#define KEY_reverse		173
+#define KEY_rewinddir		174
+#define KEY_rindex		175
+#define KEY_rmdir		176
+#define KEY_s			177
+#define KEY_say			178
+#define KEY_scalar		179
+#define KEY_seek		180
+#define KEY_seekdir		181
+#define KEY_select		182
+#define KEY_semctl		183
+#define KEY_semget		184
+#define KEY_semop		185
+#define KEY_send		186
+#define KEY_setgrent		187
+#define KEY_sethostent		188
+#define KEY_setnetent		189
+#define KEY_setpgrp		190
+#define KEY_setpriority		191
+#define KEY_setprotoent		192
+#define KEY_setpwent		193
+#define KEY_setservent		194
+#define KEY_setsockopt		195
+#define KEY_shift		196
+#define KEY_shmctl		197
+#define KEY_shmget		198
+#define KEY_shmread		199
+#define KEY_shmwrite		200
+#define KEY_shutdown		201
+#define KEY_sin			202
+#define KEY_sleep		203
+#define KEY_socket		204
+#define KEY_socketpair		205
+#define KEY_sort		206
+#define KEY_splice		207
+#define KEY_split		208
+#define KEY_sprintf		209
+#define KEY_sqrt		210
+#define KEY_srand		211
+#define KEY_stat		212
+#define KEY_state		213
+#define KEY_study		214
+#define KEY_sub			215
+#define KEY_substr		216
+#define KEY_symlink		217
+#define KEY_syscall		218
+#define KEY_sysopen		219
+#define KEY_sysread		220
+#define KEY_sysseek		221
+#define KEY_system		222
+#define KEY_syswrite		223
+#define KEY_tell		224
+#define KEY_telldir		225
+#define KEY_tie			226
+#define KEY_tied		227
+#define KEY_time		228
+#define KEY_times		229
+#define KEY_tr			230
+#define KEY_truncate		231
+#define KEY_uc			232
+#define KEY_ucfirst		233
+#define KEY_umask		234
+#define KEY_undef		235
+#define KEY_unless		236
+#define KEY_unlink		237
+#define KEY_unpack		238
+#define KEY_unshift		239
+#define KEY_untie		240
+#define KEY_until		241
+#define KEY_use			242
+#define KEY_utime		243
+#define KEY_values		244
+#define KEY_vec			245
+#define KEY_wait		246
+#define KEY_waitpid		247
+#define KEY_wantarray		248
+#define KEY_warn		249
+#define KEY_when		250
+#define KEY_while		251
+#define KEY_write		252
+#define KEY_x			253
+#define KEY_xor			254
+#define KEY_y			255
 
 /* Generated from:
- * 29732a698b229f9e5f475fbb191f71c335c9e8d05b6168fe29e61c34c4f10bd2 regen/keywords.pl
+ * e5a540774760ea54c761ef17ee4a153cc264e9a700b817d561e390730c457406 regen/keywords.pl
  * ex: set ro: */
diff --git a/opcode.h b/opcode.h
index 5f242a01a3..0a9628da92 100644
--- a/opcode.h
+++ b/opcode.h
@@ -521,6 +521,7 @@ EXTCONST char* const PL_op_name[] = {
 	"rvalues",
 	"coreargs",
 	"runcv",
+	"fc",
 };
 #endif
 
@@ -901,6 +902,7 @@ EXTCONST char* const PL_op_desc[] = {
 	"values on reference",
 	"CORE:: subroutine",
 	"__SUB__",
+	"fc",
 };
 #endif
 
@@ -1295,6 +1297,7 @@ EXT Perl_ppaddr_t PL_ppaddr[] /* or perlvars.h */
 	Perl_pp_rvalues,	/* implemented by Perl_pp_rkeys */
 	Perl_pp_coreargs,
 	Perl_pp_runcv,
+	Perl_pp_fc,
 }
 #endif
 #ifdef PERL_PPADDR_INITED
@@ -1686,6 +1689,7 @@ EXT Perl_check_t PL_check[] /* or perlvars.h */
 	Perl_ck_each,		/* rvalues */
 	Perl_ck_null,		/* coreargs */
 	Perl_ck_null,		/* runcv */
+	Perl_ck_fun,		/* fc */
 }
 #endif
 #ifdef PERL_CHECK_INITED
@@ -2071,6 +2075,7 @@ EXTCONST U32 PL_opargs[] = {
 	0x00001b08,	/* rvalues */
 	0x00000600,	/* coreargs */
 	0x00000004,	/* runcv */
+	0x00009b8e,	/* fc */
 };
 #endif
 
diff --git a/opnames.h b/opnames.h
index 5d855ec447..8b6a39a161 100644
--- a/opnames.h
+++ b/opnames.h
@@ -387,10 +387,11 @@ typedef enum opcode {
 	OP_RVALUES	 = 370,
 	OP_COREARGS	 = 371,
 	OP_RUNCV	 = 372,
+	OP_FC		 = 373,
 	OP_max		
 } opcode;
 
-#define MAXO 373
+#define MAXO 374
 
 /* the OP_IS_* macros are optimized to a simple range check because
     all the member OPs are contiguous in regen/opcodes table.
diff --git a/pp.c b/pp.c
index 2bc1a1a34f..1dc04608e4 100644
--- a/pp.c
+++ b/pp.c
@@ -4117,6 +4117,157 @@ PP(pp_quotemeta)
     RETURN;
 }
 
+PP(pp_fc)
+{
+    dVAR;
+    dTARGET;
+    dSP;
+    SV *source = TOPs;
+    STRLEN len;
+    STRLEN min;
+    SV *dest;
+    const U8 *s;
+    const U8 *send;
+    U8 *d;
+    U8 tmpbuf[UTF8_MAXBYTES * UTF8_MAX_FOLD_CHAR_EXPAND + 1];
+    const bool full_folding = TRUE;
+    const U8 flags = ( full_folding      ? FOLD_FLAGS_FULL   : 0 )
+                   | ( IN_LOCALE_RUNTIME ? FOLD_FLAGS_LOCALE : 0 );
+
+    /* This is a facsimile of pp_lc, but with a thousand bugs thanks to me.
+     * You are welcome(?) -Hugmeir
+     */
+
+    SvGETMAGIC(source);
+
+    dest = TARG;
+
+    if (SvOK(source)) {
+        s = (const U8*)SvPV_nomg_const(source, len);
+    } else {
+        if (ckWARN(WARN_UNINITIALIZED))
+	    report_uninit(source);
+	s = (const U8*)"";
+	len = 0;
+    }
+
+    min = len + 1;
+
+    SvUPGRADE(dest, SVt_PV);
+    d = (U8*)SvGROW(dest, min);
+    (void)SvPOK_only(dest);
+
+    SETs(dest);
+
+    send = s + len;
+    if (DO_UTF8(source)) { /* UTF-8 flagged string. */
+        bool tainted = FALSE;
+        while (s < send) {
+            const STRLEN u = UTF8SKIP(s);
+            STRLEN ulen;
+
+            _to_utf8_fold_flags(s, tmpbuf, &ulen, flags, &tainted);
+
+            if (ulen > u && (SvLEN(dest) < (min += ulen - u))) {
+                const UV o = d - (U8*)SvPVX_const(dest);
+                SvGROW(dest, min);
+                d = (U8*)SvPVX(dest) + o;
+            }
+
+            Copy(tmpbuf, d, ulen, U8);
+            d += ulen;
+            s += u;
+        }
+        SvUTF8_on(dest);
+	if (tainted) {
+	    TAINT;
+	    SvTAINTED_on(dest);
+	}
+    } /* Unflagged string */
+    else {
+        /* For locale, bytes, and nothing, the behavior is supposed to be the
+         * same as lc().
+         */
+        if ( IN_LOCALE_RUNTIME ) { /* Under locale */
+            TAINT;
+            SvTAINTED_on(dest);
+            for (; s < send; d++, s++)
+                *d = toLOWER_LC(*s);
+        }
+        else if ( !IN_UNI_8_BIT ) { /* Under nothing, or bytes */
+            for (; s < send; d++, s++)
+                *d = toLOWER(*s);
+        }
+        else {
+            /* For ASCII and the Latin-1 range, there's only two troublesome folds,
+            * \x{DF} (\N{LATIN SMALL LETTER SHARP S}), which under full casefolding
+            * becomes 'ss', and \x{B5} (\N{MICRO SIGN}), which under any fold becomes
+            * \x{3BC} (\N{GREEK SMALL LETTER MU}) -- For the rest, the casefold is
+            * their lowercase.
+            */
+            for (; s < send; d++, s++) {
+                if (*s == MICRO_SIGN) {
+                    /* \N{MICRO SIGN}'s casefold is \N{GREEK SMALL LETTER MU}, which
+                    * is outside of the latin-1 range. There's a couple of ways to
+                    * deal with this -- khw discusses them in pp_lc/uc, so go there :)
+                    * What we do here is upgrade what we had already casefolded,
+                    * then enter an inner loop that appends the rest of the characters
+                    * as UTF-8.
+                    */
+                    len = d - (U8*)SvPVX_const(dest);
+                    SvCUR_set(dest, len);
+                    len = sv_utf8_upgrade_flags_grow(dest,
+                                                SV_GMAGIC|SV_FORCE_UTF8_UPGRADE,
+                                                (send -s) * UTF8_MAX_FOLD_CHAR_EXPAND + 1);
+                    d = (U8*)SvPVX(dest) + len;
+
+                    CAT_UNI_TO_UTF8_TWO_BYTE(d, GREEK_SMALL_LETTER_MU);
+                    s++;
+                    for (; s < send; s++) {
+                        STRLEN ulen;
+                        UV fc = _to_uni_fold_flags(*s, tmpbuf, &ulen, flags);
+                        if UNI_IS_INVARIANT(fc) {
+                            if ( full_folding && *s == LATIN_SMALL_LETTER_SHARP_S) {
+                                *d++ = 's';
+                                *d++ = 's';
+                            }
+                            else
+                                *d++ = (U8)fc;
+                        }
+                        else {
+                            Copy(tmpbuf, d, ulen, U8);
+                            d += ulen;
+                        }
+                    }
+                    break;
+                }
+                else if (full_folding && *s == LATIN_SMALL_LETTER_SHARP_S) {
+                    /* Under full casefolding, LATIN SMALL LETTER SHARP S becomes "ss",
+                    * which may require growing the SV.
+                    */
+                    if (SvLEN(dest) < ++min) {
+                        const UV o = d - (U8*)SvPVX_const(dest);
+                        SvGROW(dest, min);
+                        d = (U8*)SvPVX(dest) + o;
+                     }
+                    *(d)++ = 's';
+                    *d = 's';
+                }
+                else { /* If it's not one of those two, the fold is their lower case */
+                    *d = toLOWER_LATIN1(*s);
+                }
+             }
+        }
+    }
+    *d = '\0';
+    SvCUR_set(dest, d - (U8*)SvPVX_const(dest));
+
+    if (SvTAINTED(source))
+	SvTAINT(dest);
+    SvSETMAGIC(dest);
+    RETURN;
+}
+
 /* Arrays. */
 
 PP(pp_aslice)
diff --git a/pp_proto.h b/pp_proto.h
index 96bcacbe6b..52011dadd3 100644
--- a/pp_proto.h
+++ b/pp_proto.h
@@ -66,6 +66,7 @@ PERL_CALLCONV OP *Perl_pp_eq(pTHX);
 PERL_CALLCONV OP *Perl_pp_exec(pTHX);
 PERL_CALLCONV OP *Perl_pp_exists(pTHX);
 PERL_CALLCONV OP *Perl_pp_exit(pTHX);
+PERL_CALLCONV OP *Perl_pp_fc(pTHX);
 PERL_CALLCONV OP *Perl_pp_fileno(pTHX);
 PERL_CALLCONV OP *Perl_pp_flip(pTHX);
 PERL_CALLCONV OP *Perl_pp_flock(pTHX);
diff --git a/regen/keywords.pl b/regen/keywords.pl
index 3e0b0d36f0..b783d08f77 100755
--- a/regen/keywords.pl
+++ b/regen/keywords.pl
@@ -49,6 +49,8 @@ my %feature_kw = (
 	evalbytes=>'evalbytes',
 
 	__SUB__ => '__SUB__',
+
+	fc      => 'fc',
 	);
 
 my %pos = map { ($_ => 1) } @{$by_strength{'+'}};
@@ -176,6 +178,7 @@ __END__
 +exists
 -exit
 -exp
+-fc
 -fcntl
 -fileno
 -flock
diff --git a/regen/opcodes b/regen/opcodes
index 23f6d2852a..22cc9133fd 100644
--- a/regen/opcodes
+++ b/regen/opcodes
@@ -545,3 +545,6 @@ rvalues		values on reference			ck_each		t%	S
 coreargs	CORE:: subroutine	ck_null		$	
 
 runcv		__SUB__			ck_null		s0
+
+# fc and \F
+fc		fc			ck_fun		fstu%	S?
diff --git a/t/op/coreamp.t b/t/op/coreamp.t
index 3c0a4a412e..78ced66304 100644
--- a/t/op/coreamp.t
+++ b/t/op/coreamp.t
@@ -434,6 +434,16 @@ is $^A,        ' 1       2', 'effect of &myformline';
 lis [&myformline('@')], [1], '&myformline in list context';
 
 test_proto 'exp';
+
+test_proto 'fc';
+$tests += 2;
+{
+  my $sharp_s = "\xdf";
+  is &myfc($sharp_s), $sharp_s, '&fc, no unicode_strings';
+  use feature 'unicode_strings';
+  is &myfc($sharp_s), "ss", '&fc, unicode_strings';
+}
+
 test_proto 'fcntl';
 
 test_proto 'fileno';
diff --git a/t/op/cproto.t b/t/op/cproto.t
index dabb4bc4a6..8870df8d08 100644
--- a/t/op/cproto.t
+++ b/t/op/cproto.t
@@ -7,7 +7,7 @@ BEGIN {
 }
 
 BEGIN { require './test.pl'; }
-plan tests => 247;
+plan tests => 248;
 
 while (<DATA>) {
     chomp;
@@ -83,6 +83,7 @@ exec undef
 exists undef
 exit (;$)
 exp (_)
+fc (_)
 fcntl (*$$)
 fileno (*)
 flock (*$)
diff --git a/t/op/lc.t b/t/op/lc.t
index 22242b218d..08efdc014a 100644
--- a/t/op/lc.t
+++ b/t/op/lc.t
@@ -1,18 +1,39 @@
 #!./perl
 
+# This file is intentionally encoded in latin-1.
+
 BEGIN {
     chdir 't';
     @INC = '../lib';
     require './test.pl';
 }
 
-plan tests => 93;
+use feature qw( fc );
+
+plan tests => 124;
 
 is(lc(undef),	   "", "lc(undef) is ''");
 is(lcfirst(undef), "", "lcfirst(undef) is ''");
 is(uc(undef),	   "", "uc(undef) is ''");
 is(ucfirst(undef), "", "ucfirst(undef) is ''");
 
+{
+    no feature 'fc';
+    is(CORE::fc(undef), "", "fc(undef) is ''");
+    is(CORE::fc(''),    "", "fc('') is ''");
+
+    local $@;
+    eval { fc("eeyup") };
+    like($@, qr/Undefined subroutine &main::fc/, "fc() throws an exception,");
+
+    {
+        use feature 'fc';
+        local $@;
+        eval { fc("eeyup") };
+        ok(!$@, "...but works after requesting the feature");
+    }
+}
+
 $a = "HELLO.* world";
 $b = "hello.* WORLD";
 
@@ -21,27 +42,32 @@ is("\u$a"         , "HELLO\.\* world",      '\u');
 is("\l$a"         , "hELLO\.\* world",      '\l');
 is("\U$a"         , "HELLO\.\* WORLD",      '\U');
 is("\L$a"         , "hello\.\* world",      '\L');
+is("\F$a"         , "hello\.\* world",      '\F');
 
 is(quotemeta($a)  , "HELLO\\.\\*\\ world",  'quotemeta');
 is(ucfirst($a)    , "HELLO\.\* world",      'ucfirst');
 is(lcfirst($a)    , "hELLO\.\* world",      'lcfirst');
 is(uc($a)         , "HELLO\.\* WORLD",      'uc');
 is(lc($a)         , "hello\.\* world",      'lc');
+is(fc($a)         , "hello\.\* world",      'fc');
 
 is("\Q$b\E."      , "hello\\.\\*\\ WORLD.", '\Q\E hello.* WORLD');
 is("\u$b"         , "Hello\.\* WORLD",      '\u');
 is("\l$b"         , "hello\.\* WORLD",      '\l');
 is("\U$b"         , "HELLO\.\* WORLD",      '\U');
 is("\L$b"         , "hello\.\* world",      '\L');
+is("\F$b"         , "hello\.\* world",      '\F');
 
 is(quotemeta($b)  , "hello\\.\\*\\ WORLD",  'quotemeta');
 is(ucfirst($b)    , "Hello\.\* WORLD",      'ucfirst');
 is(lcfirst($b)    , "hello\.\* WORLD",      'lcfirst');
 is(uc($b)         , "HELLO\.\* WORLD",      'uc');
 is(lc($b)         , "hello\.\* world",      'lc');
+is(fc($b)         , "hello\.\* world",      'fc');
 
 # \x{100} is LATIN CAPITAL LETTER A WITH MACRON; its bijective lowercase is
 # \x{101}, LATIN SMALL LETTER A WITH MACRON.
+# Which is also its foldcase.
 
 $a = "\x{100}\x{101}Aa";
 $b = "\x{101}\x{100}aA";
@@ -51,24 +77,28 @@ is("\u$a"         , "\x{100}\x{101}Aa",  '\u');
 is("\l$a"         , "\x{101}\x{101}Aa",  '\l');
 is("\U$a"         , "\x{100}\x{100}AA",  '\U');
 is("\L$a"         , "\x{101}\x{101}aa",  '\L');
+is("\F$a"         , "\x{101}\x{101}aa",  '\F');
 
 is(quotemeta($a)  , "\x{100}\x{101}Aa",  'quotemeta');
 is(ucfirst($a)    , "\x{100}\x{101}Aa",  'ucfirst');
 is(lcfirst($a)    , "\x{101}\x{101}Aa",  'lcfirst');
 is(uc($a)         , "\x{100}\x{100}AA",  'uc');
 is(lc($a)         , "\x{101}\x{101}aa",  'lc');
+is(fc($a)         , "\x{101}\x{101}aa",  'fc');
 
 is("\Q$b\E."      , "\x{101}\x{100}aA.", '\Q\E \x{101}\x{100}aA');
 is("\u$b"         , "\x{100}\x{100}aA",  '\u');
 is("\l$b"         , "\x{101}\x{100}aA",  '\l');
 is("\U$b"         , "\x{100}\x{100}AA",  '\U');
 is("\L$b"         , "\x{101}\x{101}aa",  '\L');
+is("\F$b"         , "\x{101}\x{101}aa",  '\F');
 
 is(quotemeta($b)  , "\x{101}\x{100}aA",  'quotemeta');
 is(ucfirst($b)    , "\x{100}\x{100}aA",  'ucfirst');
 is(lcfirst($b)    , "\x{101}\x{100}aA",  'lcfirst');
 is(uc($b)         , "\x{100}\x{100}AA",  'uc');
 is(lc($b)         , "\x{101}\x{101}aa",  'lc');
+is(fc($b)         , "\x{101}\x{101}aa",  'fc');
 
 # \x{DF} is LATIN SMALL LETTER SHARP S, its uppercase is SS or \x{53}\x{53};
 # \x{149} is LATIN SMALL LETTER N PRECEDED BY APOSTROPHE, its uppercase is
@@ -83,6 +113,15 @@ is(latin1_to_native("\U\x{DF}aB\x{149}cD"), latin1_to_native("SSAB\x{2BC}NCD"),
 is(latin1_to_native("\L\x{DF}aB\x{149}cD"), latin1_to_native("\x{DF}ab\x{149}cd"),
        "multicharacter lowercase");
 
+# \x{DF} is LATIN SMALL LETTER SHARP S, its foldcase is ss or \x{73}\x{73};
+# \x{149} is LATIN SMALL LETTER N PRECEDED BY APOSTROPHE, its foldcase is
+# \x{2BC}\x{6E} or MODIFIER LETTER APOSTROPHE and n.
+# Note that is this further tested in t/uni/fold.t
+
+is(latin1_to_native("\F\x{DF}aB\x{149}cD"), latin1_to_native("ssab\x{2BC}ncd"),
+       "multicharacter foldcase");
+
+
 # titlecase is used for \u / ucfirst.
 
 # \x{587} is ARMENIAN SMALL LIGATURE ECH YIWN and its titlecase is
@@ -91,16 +130,18 @@ is(latin1_to_native("\L\x{DF}aB\x{149}cD"), latin1_to_native("\x{DF}ab\x{149}cd"
 # \x{587} itself
 # and its uppercase is
 # \x{535}\x{552} ARMENIAN CAPITAL LETTER ECH + ARMENIAN CAPITAL LETTER YIWN
+# The foldcase is \x{565}\x{582} ARMENIAN SMALL LETTER ECH + ARMENIAN SMALL LETTER YIWN
 
 $a = "\x{587}";
 
 is("\L\x{587}" , "\x{587}",        "ligature lowercase");
 is("\u\x{587}" , "\x{535}\x{582}", "ligature titlecase");
 is("\U\x{587}" , "\x{535}\x{552}", "ligature uppercase");
+is("\F\x{587}" , "\x{565}\x{582}", "ligature foldcase");
 
 # mktables had problems where many-to-one case mappings didn't work right.
 # The lib/uni/fold.t should give the fourth folding, "casefolding", a good
-# workout (one cannot directly get that from Perl). 
+# workout.
 # \x{01C4} is LATIN CAPITAL LETTER DZ WITH CARON
 # \x{01C5} is LATIN CAPITAL LETTER D WITH SMALL LETTER Z WITH CARON
 # \x{01C6} is LATIN SMALL LETTER DZ WITH CARON
@@ -127,6 +168,9 @@ is($c , $a, "Using s///e to change case.");
 ($c = $a) =~ s/(\p{IsWord}+)/uc($1)/ge;
 is($c , $b, "Using s///e to change case.");
 
+($c = $a) =~ s/(\p{IsWord}+)/fc($1)/ge;
+is($c , $a, "Using s///e to foldcase.");
+
 ($c = $b) =~ s/(\p{IsWord}+)/lcfirst($1)/ge;
 is($c , "\x{3c3}FOO.bAR", "Using s///e to change case.");
 
@@ -165,6 +209,11 @@ for ("a\x{100}", "�yz\x{100}") { # � to Ss (different length)
     is(substr(ucfirst($_), 0), ucfirst($_), "[perl #38619] ucfirst");
 }
 
+#fc() didn't exist back then, but coverage is coverage.
+for ("a\x{100}", "�yz\x{100}", "xyz\x{100}", "XYZ\x{100}") { # � to Ss (different length)
+    is(substr(fc($_), 0), fc($_), "[perl #38619] fc");
+}
+
 # Related to [perl #38619]
 # the original report concerns PERL_MAGIC_utf8.
 # these cases concern PERL_MAGIC_regex_global.
@@ -187,11 +236,23 @@ for (map { $_ } "A\x{100}", "ABC\x{100}", "\x{100}") {
     is($result, $expect, "[perl #38619]");
 }
 
+for (map { $_ } "A\x{100}", "ABC\x{100}", "\x{100}") {
+    chop; # get ("A", "ABC", "") in utf8
+    my $return =  fc($_) =~ /\G(.?)/g;
+    my $result = $return ? $1 : "not";
+    my $expect = (fc($_) =~ /(.?)/g)[0];
+    is($return, 1,       "[perl #38619]");
+    is($result, $expect, "[perl #38619]");
+}
+
 for (1, 4, 9, 16, 25) {
     is(uc "\x{03B0}" x $_, "\x{3a5}\x{308}\x{301}" x $_,
        'uc U+03B0 grows threefold');
 
     is(lc "\x{0130}" x $_, "i\x{307}" x $_, 'lc U+0130 grows');
+
+    is(fc "\x{03B0}" x $_, "\x{3C5}\x{308}\x{301}" x $_,
+       'fc U+03B0 grows threefold');
 }
 
 # bug #43207
@@ -201,5 +262,12 @@ for ("$temp") {
     is($_, "Hello");
 }
 
+# bug #43207
+my $temp = "Hello";
+for ("$temp") {
+    fc $_;
+    is($_, "Hello");
+}
+
 # new in Unicode 5.1.0
 is(lc("\x{1E9E}"), "\x{df}", "lc(LATIN CAPITAL LETTER SHARP S)");
diff --git a/t/op/taint.t b/t/op/taint.t
index ca52f89178..0b626f340c 100644
--- a/t/op/taint.t
+++ b/t/op/taint.t
@@ -17,7 +17,7 @@ BEGIN {
 use strict;
 use Config;
 
-plan tests => 787;
+plan tests => 791;
 
 $| = 1;
 
@@ -2176,6 +2176,19 @@ for(1,2) {
 }
 pass("no death when TARG of ref is tainted");
 
+{
+    use feature 'fc';
+    use locale;
+    my ($latin1, $utf8) = ("\xDF") x 2;
+    utf8::downgrade($latin1);
+    utf8::upgrade($utf8);
+
+    is_tainted fc($latin1), "under locale, lc(latin1) taints the result";
+    is_tainted fc($utf8), "under locale, lc(utf8) taints the result";
+
+    is_tainted "\F$latin1", "under locale, \\Flatin1 taints the result";
+    is_tainted "\F$utf8", "under locale, \\Futf8 taints the result";
+}
 
 # This may bomb out with the alarm signal so keep it last
 SKIP: {
diff --git a/t/uni/fold.t b/t/uni/fold.t
index d481b53142..3dde70469e 100644
--- a/t/uni/fold.t
+++ b/t/uni/fold.t
@@ -2,6 +2,7 @@ use strict;
 use warnings;
 
 # re/fold_grind.t has more complex tests, but doesn't test every fold
+# This file also tests the fc() keyword.
 
 BEGIN {
     chdir 't' if -d 't';
@@ -9,25 +10,27 @@ BEGIN {
     require './test.pl';
 }
 
+use feature 'unicode_strings';
+
 binmode *STDOUT, ":utf8";
 
 our $TODO;
 
 plan("no_plan");
-
 # Read in the official case folding definitions.
 my $CF = '../lib/unicore/CaseFolding.txt';
 
 die qq[$0: failed to open "$CF": $!\n] if ! open(my $fh, "<", $CF);
 
 my @CF;
+my @simple_folds;
 my %reverse_fold;
 while (<$fh>) {
-    # Skip S since we are going for 'F'ull case folding.  I is obsolete starting
-    # with Unicode 3.2, but leaving it in does no harm, and allows backward
-    # compatibility
+    # We only use 'S' in simple folded fc(), since the regex engine uses
+    # 'F'ull case folding.  I is obsolete starting with Unicode 3.2, but
+    # leaving it in does no harm, and allows backward compatibility
     next unless my ($code, $type, $mapping, $name) = $_ =~
-            /^([0-9A-F]+); ([CFI]); ((?:[0-9A-F]+)(?: [0-9A-F]+)*); \# (.+)/;
+            /^([0-9A-F]+); ([CFIS]); ((?:[0-9A-F]+)(?: [0-9A-F]+)*); \# (.+)/;
 
     # Convert any 0-255 range chars to native.
     $code = sprintf("%04X", ord_latin1_to_native(hex $code)) if hex $code < 0x100;
@@ -35,6 +38,11 @@ while (<$fh>) {
                                 sprintf("%04X", ord_latin1_to_native(hex $_)) }
                                                             split / /, $mapping;
 
+    if ( $type eq "S" ) {
+        push @simple_folds, [$code, $mapping, $type, $name];
+        next;
+    }
+
     push @CF, [$code, $mapping, $type, $name];
 
     # Get the inverse fold for single-char mappings.
@@ -43,6 +51,19 @@ while (<$fh>) {
 
 close($fh) or die "$0 Couldn't close $CF";
 
+foreach my $test_ref ( @simple_folds ) {
+    use feature 'fc';
+    my ($code, $mapping, $type, $name) = @$test_ref;
+    my $c = pack("U0U*", hex $code);
+    my $f = pack("U0U*", map { hex } split " ", $mapping);
+
+    my $against = join "", "qq{", map("\\x{$_}", split " ", $mapping), "}";
+    {
+        isnt(fc($c), $f, "$code - $name - $mapping - $type - Full casefolding, fc(\\x{$code}) ne $against");
+        isnt("\F$c", $f, "$code - $name - $mapping - $type - Full casefolding, qq{\\F\\x{$code}} ne $against");
+    }
+}
+
 foreach my $test_ref (@CF) {
     my ($code, $mapping, $type, $name) = @$test_ref;
     my $c = pack("U0U*", hex $code);
@@ -60,6 +81,24 @@ foreach my $test_ref (@CF) {
         ok eval $test, "$code - $name - $mapping - $type - $test";
     }
 
+    {
+        # fc() tests
+        my $against = join "", "qq{", map("\\x{$_}", split " ", $mapping), "}";
+        is(CORE::fc($c), $f,
+            "$code - $name - $mapping - $type - fc(\\x{$code}) eq $against");
+        is("\F$c", $f, "$code - $name - $mapping - $type - qq{\\F\\x{$code}} eq $against");
+
+        # And here we test bytes. For [A-Za-z0-9], the fold is the same as lc under
+        # bytes. For everything else, it's the bytes that formed the original string.
+        if ( $c =~ /[A-Za-z0-9]/ ) {
+            use bytes;
+            is(CORE::fc($c), lc($c), "$code - $name - fc and use bytes, ascii");
+        } else {
+            my $copy = "" . $c;
+            utf8::encode($copy);
+            is($copy, do { use bytes; CORE::fc($c) }, "$code - $name - fc and use bytes");
+        }
+    }
     # Certain tests weren't convenient to put in the list above since they are
     # TODO's in multi-character folds.
     if ($f_length == 1) {
@@ -115,6 +154,288 @@ foreach my $test_ref (@CF) {
     }
 }
 
+{
+    use utf8;
+    use feature qw(fc);
+    # These three come from the ICU project's test suite, more especifically
+    # http://icu.sourcearchive.com/documentation/4.4~rc1-1/strcase_8cpp-source.html
+
+    my $s = "A\N{U+00df}\N{U+00b5}\N{U+fb03}\N{U+1040C}\N{U+0130}\N{U+0131}";
+    #\N{LATIN CAPITAL LETTER A}\N{LATIN SMALL LETTER SHARP S}\N{MICRO SIGN}\N{LATIN SMALL LIGATURE FFI}\N{DESERET CAPITAL LETTER AY}\N{LATIN CAPITAL LETTER I WITH DOT ABOVE}\N{LATIN SMALL LETTER DOTLESS I}
+
+    my $f = "ass\N{U+03bc}ffi\N{U+10434}i\N{U+0307}\N{U+0131}";
+    #\N{LATIN SMALL LETTER A}\N{LATIN SMALL LETTER S}\N{LATIN SMALL LETTER S}\N{GREEK SMALL LETTER MU}\N{LATIN SMALL LETTER F}\N{LATIN SMALL LETTER F}\N{LATIN SMALL LETTER I}\N{DESERET SMALL LETTER AY}\N{LATIN SMALL LETTER I}\N{COMBINING DOT ABOVE}\N{LATIN SMALL LETTER DOTLESS I}
+
+    is(fc($s), $f, "ICU's casefold test passes");
+    is("\F$s", $f, "ICU's casefold test passes");
+
+    is( fc("aBİIıϐßﬃ񟿿"), "abi̇iıβssffi񟿿" );
+    is( "\FaBİIıϐßﬃ񟿿", "abi̇iıβssffi񟿿" );
+#    TODO: {
+#        local $::TODO = "turkic special cases";
+#        is( fc "aBİIıϐßﬃ񟿿", "abiııβssffi񟿿" );
+#    }
+
+    # The next batch come from http://www.devdaily.com/java/jwarehouse/lucene/contrib/icu/src/test/org/apache/lucene/analysis/icu/TestICUFoldingFilter.java.shtml
+    # Except the article got most casings wrong. Or maybe Lucene does.
+
+    is( fc("This is a test"), "this is a test" );
+    is( fc("Ruß"), "russ"    );
+    is( fc("ΜΆΪΟΣ"), "μάϊοσ" );
+    is( fc("Μάϊος"), "μάϊοσ" );
+    is( fc("𐐖"), "𐐾"       );
+    is( fc("r\xe9sum\xe9"), "r\xe9sum\xe9" );
+    is( fc("re\x{0301}sume\x{0301}"), "re\x{301}sume\x{301}" );
+    is( fc("ELİF"), "eli\x{307}f" );
+    is( fc("eli\x{307}f"), "eli\x{307}f");
+
+    # This batch comes from
+    # http://www.java2s.com/Open-Source/Java-Document/Internationalization-Localization/icu4j/com/ibm/icu/dev/test/lang/UCharacterCaseTest.java.htm
+    # Which uses ICU as the backend.
+
+    my @folding_mixed = (
+        "\x{61}\x{42}\x{130}\x{49}\x{131}\x{3d0}\x{df}\x{fb03}",
+        "A\x{df}\x{b5}\x{fb03}\x{1040C}\x{130}\x{131}",
+    );
+
+    my @folding_default = (
+        "\x{61}\x{62}\x{69}\x{307}\x{69}\x{131}\x{3b2}\x{73}\x{73}\x{66}\x{66}\x{69}",
+        "ass\x{3bc}ffi\x{10434}i\x{307}\x{131}",
+    );
+
+    my @folding_exclude_turkic = (
+        "\x{61}\x{62}\x{69}\x{131}\x{131}\x{3b2}\x{73}\x{73}\x{66}\x{66}\x{69}",
+        "ass\x{3bc}ffi\x{10434}i\x{131}",
+    );
+
+    is( fc($folding_mixed[1]), $folding_default[1] );
+
+    is( fc($folding_mixed[0]), $folding_default[0] );
+
+}
+
+{
+    use utf8;
+    # Table stolen from tchrist's mail in
+    # http://bugs.python.org/file23051/casing-tests.py
+    # and http://98.245.80.27/tcpc/OSCON2011/case-test.python3
+    # For reference, it's a longer version of what he posted here:
+    # http://stackoverflow.com/questions/6991038/case-insensitive-storage-and-unicode-compatibility
+
+    #Couple of repeats because I'm lazy, not tchrist's fault.
+
+    #This should probably go in t/op/lc.t
+
+    my @test_table = (
+# ORIG LC_SIMPLE TC_SIMPLE UC_SIMPLE LC_FULL TC_FULL UC_FULL FC_SIMPLE FC_TURKIC FC_FULL
+[ 'þǽr rihtes', 'þǽr rihtes', 'Þǽr Rihtes', 'ÞǼR RIHTES', 'þǽr rihtes', 'Þǽr Rihtes', 'ÞǼR RIHTES', 'þǽr rihtes', 'þǽr rihtes', 'þǽr rihtes',  ],
+[ 'duȝeðlice', 'duȝeðlice', 'Duȝeðlice', 'DUȜEÐLICE', 'duȝeðlice', 'Duȝeðlice', 'DUȜEÐLICE', 'duȝeðlice', 'duȝeðlice', 'duȝeðlice',  ],
+[ 'Ævar Arnfjörð Bjarmason', 'ævar arnfjörð bjarmason', 'Ævar Arnfjörð Bjarmason', 'ÆVAR ARNFJÖRÐ BJARMASON', 'ævar arnfjörð bjarmason', 'Ævar Arnfjörð Bjarmason', 'ÆVAR ARNFJÖRÐ BJARMASON', 'ævar arnfjörð bjarmason', 'ævar arnfjörð bjarmason', 'ævar arnfjörð bjarmason',  ],
+[ 'Кириллица', 'кириллица', 'Кириллица', 'КИРИЛЛИЦА', 'кириллица', 'Кириллица', 'КИРИЛЛИЦА', 'кириллица', 'кириллица', 'кириллица',  ],
+[ 'ĳ', 'ĳ', 'Ĳ', 'Ĳ', 'ĳ', 'Ĳ', 'Ĳ', 'ĳ', 'ĳ', 'ĳ',  ],
+[ 'Van Dĳke', 'van dĳke', 'Van Dĳke', 'VAN DĲKE', 'van dĳke', 'Van Dĳke', 'VAN DĲKE', 'van dĳke', 'van dĳke', 'van dĳke',  ],
+[ 'VAN DĲKE', 'van dĳke', 'Van Dĳke', 'VAN DĲKE', 'van dĳke', 'Van Dĳke', 'VAN DĲKE', 'van dĳke', 'van dĳke', 'van dĳke',  ],
+[ 'eﬃcient', 'eﬃcient', 'Eﬃcient', 'EﬃCIENT', 'eﬃcient', 'Eﬃcient', 'EFFICIENT', 'eﬃcient', 'efficient', 'efficient',  ],
+[ 'ﬂour', 'ﬂour', 'ﬂour', 'ﬂOUR', 'ﬂour', 'Flour', 'FLOUR', 'ﬂour', 'flour', 'flour',  ],
+[ 'ﬂour and water', 'ﬂour and water', 'ﬂour And Water', 'ﬂOUR AND WATER', 'ﬂour and water', 'Flour And Water', 'FLOUR AND WATER', 'ﬂour and water', 'flour and water', 'flour and water',  ],
+[ 'ǳur', 'ǳur', 'ǲur', 'ǱUR', 'ǳur', 'ǲur', 'ǱUR', 'ǳur', 'ǳur', 'ǳur',  ],
+[ 'ǲur', 'ǳur', 'ǲur', 'ǱUR', 'ǳur', 'ǲur', 'ǱUR', 'ǳur', 'ǳur', 'ǳur',  ],
+[ 'ǱUR', 'ǳur', 'ǲur', 'ǱUR', 'ǳur', 'ǲur', 'ǱUR', 'ǳur', 'ǳur', 'ǳur',  ],
+[ 'ǳur mountain', 'ǳur mountain', 'ǲur Mountain', 'ǱUR MOUNTAIN', 'ǳur mountain', 'ǲur Mountain', 'ǱUR MOUNTAIN', 'ǳur mountain', 'ǳur mountain', 'ǳur mountain',  ],
+[ 'ǲur Mountain', 'ǳur mountain', 'ǲur Mountain', 'ǱUR MOUNTAIN', 'ǳur mountain', 'ǲur Mountain', 'ǱUR MOUNTAIN', 'ǳur mountain', 'ǳur mountain', 'ǳur mountain',  ],
+[ 'ǱUR MOUNTAIN', 'ǳur mountain', 'ǲur Mountain', 'ǱUR MOUNTAIN', 'ǳur mountain', 'ǲur Mountain', 'ǱUR MOUNTAIN', 'ǳur mountain', 'ǳur mountaın', 'ǳur mountain',  ],
+[ 'poſt', 'poſt', 'Poſt', 'POST', 'poſt', 'Poſt', 'POST', 'post', 'post', 'post',  ],
+[ 'poﬅ', 'poﬅ', 'Poﬅ', 'POﬅ', 'poﬅ', 'Poﬅ', 'POST', 'poﬅ', 'post', 'post',  ],
+[ 'ﬅop', 'ﬅop', 'ﬅop', 'ﬅOP', 'ﬅop', 'Stop', 'STOP', 'ﬅop', 'stop', 'stop',  ],
+[ 'tschüß', 'tschüß', 'Tschüß', 'TSCHÜß', 'tschüß', 'Tschüß', 'TSCHÜSS', 'tschüß', 'tschüss', 'tschüss',  ],
+[ 'TSCHÜẞ', 'tschüß', 'Tschüß', 'TSCHÜẞ', 'tschüß', 'Tschüß', 'TSCHÜẞ', 'tschüß', 'tschüss', 'tschüss',  ],
+[ 'weiß', 'weiß', 'Weiß', 'WEIß', 'weiß', 'Weiß', 'WEISS', 'weiß', 'weiss', 'weiss',  ],
+[ 'WEIẞ', 'weiß', 'Weiß', 'WEIẞ', 'weiß', 'Weiß', 'WEIẞ', 'weiß', 'weıss', 'weiss',  ],
+[ 'ẞIEW', 'ßiew', 'ẞiew', 'ẞIEW', 'ßiew', 'ẞiew', 'ẞIEW', 'ßiew', 'ssıew', 'ssiew',  ],
+[ 'ᾲ', 'ᾲ', 'Ὰͅ', 'ᾺΙ', 'ᾲ', 'Ὰͅ', 'ᾺΙ', 'ὰι', 'ὰι', 'ὰι',  ],
+[ 'Ὰι', 'ὰι', 'Ὰι', 'ᾺΙ', 'ὰι', 'Ὰι', 'ᾺΙ', 'ὰι', 'ὰι', 'ὰι',  ],
+[ 'ᾺΙ', 'ὰι', 'Ὰι', 'ᾺΙ', 'ὰι', 'Ὰι', 'ᾺΙ', 'ὰι', 'ὰι', 'ὰι',  ],
+[ 'ᾲ', 'ᾲ', 'ᾲ', 'ᾲ', 'ᾲ', 'Ὰͅ', 'ᾺΙ', 'ᾲ', 'ὰι', 'ὰι',  ],
+[ 'Ὰͅ', 'ᾲ', 'Ὰͅ', 'ᾺΙ', 'ᾲ', 'Ὰͅ', 'ᾺΙ', 'ὰι', 'ὰι', 'ὰι',  ],
+[ 'ᾺΙ', 'ὰι', 'Ὰι', 'ᾺΙ', 'ὰι', 'Ὰι', 'ᾺΙ', 'ὰι', 'ὰι', 'ὰι',  ],
+[ 'ᾲ στο διάολο', 'ᾲ στο διάολο', 'ᾲ Στο Διάολο', 'ᾲ ΣΤΟ ΔΙΆΟΛΟ', 'ᾲ στο διάολο', 'Ὰͅ Στο Διάολο', 'ᾺΙ ΣΤΟ ΔΙΆΟΛΟ', 'ᾲ στο διάολο', 'ὰι στο διάολο', 'ὰι στο διάολο',  ],
+[ 'ᾲ στο διάολο', 'ᾲ στο διάολο', 'Ὰͅ Στο Διάολο', 'ᾺΙ ΣΤΟ ΔΙΆΟΛΟ', 'ᾲ στο διάολο', 'Ὰͅ Στο Διάολο', 'ᾺΙ ΣΤΟ ΔΙΆΟΛΟ', 'ὰι στο διάολο', 'ὰι στο διάολο', 'ὰι στο διάολο',  ],
+[ '𐐼𐐯𐑅𐐨𐑉𐐯𐐻', '𐐼𐐯𐑅𐐨𐑉𐐯𐐻', '𐐔𐐯𐑅𐐨𐑉𐐯𐐻', '𐐔𐐇𐐝𐐀𐐡𐐇𐐓', '𐐼𐐯𐑅𐐨𐑉𐐯𐐻', '𐐔𐐯𐑅𐐨𐑉𐐯𐐻', '𐐔𐐇𐐝𐐀𐐡𐐇𐐓', '𐐼𐐯𐑅𐐨𐑉𐐯𐐻', '𐐼𐐯𐑅𐐨𐑉𐐯𐐻', '𐐼𐐯𐑅𐐨𐑉𐐯𐐻',  ],
+[ '𐐔𐐯𐑅𐐨𐑉𐐯𐐻', '𐐼𐐯𐑅𐐨𐑉𐐯𐐻', '𐐔𐐯𐑅𐐨𐑉𐐯𐐻', '𐐔𐐇𐐝𐐀𐐡𐐇𐐓', '𐐼𐐯𐑅𐐨𐑉𐐯𐐻', '𐐔𐐯𐑅𐐨𐑉𐐯𐐻', '𐐔𐐇𐐝𐐀𐐡𐐇𐐓', '𐐼𐐯𐑅𐐨𐑉𐐯𐐻', '𐐼𐐯𐑅𐐨𐑉𐐯𐐻', '𐐼𐐯𐑅𐐨𐑉𐐯𐐻',  ],
+[ '𐐔𐐇𐐝𐐀𐐡𐐇𐐓', '𐐼𐐯𐑅𐐨𐑉𐐯𐐻', '𐐔𐐯𐑅𐐨𐑉𐐯𐐻', '𐐔𐐇𐐝𐐀𐐡𐐇𐐓', '𐐼𐐯𐑅𐐨𐑉𐐯𐐻', '𐐔𐐯𐑅𐐨𐑉𐐯𐐻', '𐐔𐐇𐐝𐐀𐐡𐐇𐐓', '𐐼𐐯𐑅𐐨𐑉𐐯𐐻', '𐐼𐐯𐑅𐐨𐑉𐐯𐐻', '𐐼𐐯𐑅𐐨𐑉𐐯𐐻',  ],
+[ 'henry ⅷ', 'henry ⅷ', 'Henry Ⅷ', 'HENRY Ⅷ', 'henry ⅷ', 'Henry Ⅷ', 'HENRY Ⅷ', 'henry ⅷ', 'henry ⅷ', 'henry ⅷ',  ],
+[ 'Henry Ⅷ', 'henry ⅷ', 'Henry Ⅷ', 'HENRY Ⅷ', 'henry ⅷ', 'Henry Ⅷ', 'HENRY Ⅷ', 'henry ⅷ', 'henry ⅷ', 'henry ⅷ',  ],
+[ 'HENRY Ⅷ', 'henry ⅷ', 'Henry Ⅷ', 'HENRY Ⅷ', 'henry ⅷ', 'Henry Ⅷ', 'HENRY Ⅷ', 'henry ⅷ', 'henry ⅷ', 'henry ⅷ',  ],
+[ 'i work at ⓚ', 'i work at ⓚ', 'I Work At Ⓚ', 'I WORK AT Ⓚ', 'i work at ⓚ', 'I Work At Ⓚ', 'I WORK AT Ⓚ', 'i work at ⓚ', 'i work at ⓚ', 'i work at ⓚ',  ],
+[ 'I Work At Ⓚ', 'i work at ⓚ', 'I Work At Ⓚ', 'I WORK AT Ⓚ', 'i work at ⓚ', 'I Work At Ⓚ', 'I WORK AT Ⓚ', 'i work at ⓚ', 'ı work at ⓚ', 'i work at ⓚ',  ],
+[ 'I WORK AT Ⓚ', 'i work at ⓚ', 'I Work At Ⓚ', 'I WORK AT Ⓚ', 'i work at ⓚ', 'I Work At Ⓚ', 'I WORK AT Ⓚ', 'i work at ⓚ', 'ı work at ⓚ', 'i work at ⓚ',  ],
+[ 'istambul', 'istambul', 'Istambul', 'ISTAMBUL', 'istambul', 'Istambul', 'ISTAMBUL', 'istambul', 'istambul', 'istambul',  ],
+[ 'i̇stanbul', 'i̇stanbul', 'İstanbul', 'İSTANBUL', 'i̇stanbul', 'İstanbul', 'İSTANBUL', 'i̇stanbul', 'i̇stanbul', 'i̇stanbul',  ],
+[ 'İstanbul', 'i̇stanbul', 'İstanbul', 'İSTANBUL', 'i̇stanbul', 'İstanbul', 'İSTANBUL', 'i̇stanbul', 'ı̇stanbul', 'i̇stanbul',  ],
+[ 'İSTANBUL', 'istanbul', 'İstanbul', 'İSTANBUL', 'i̇stanbul', 'İstanbul', 'İSTANBUL', 'İstanbul', 'istanbul', 'i̇stanbul',  ],
+[ 'στιγμας', 'στιγμας', 'Στιγμας', 'ΣΤΙΓΜΑΣ', 'στιγμας', 'Στιγμας', 'ΣΤΙΓΜΑΣ', 'στιγμασ', 'στιγμασ', 'στιγμασ',  ],
+[ 'στιγμασ', 'στιγμασ', 'Στιγμασ', 'ΣΤΙΓΜΑΣ', 'στιγμασ', 'Στιγμασ', 'ΣΤΙΓΜΑΣ', 'στιγμασ', 'στιγμασ', 'στιγμασ',  ],
+[ 'ΣΤΙΓΜΑΣ', 'στιγμασ', 'Στιγμασ', 'ΣΤΙΓΜΑΣ', 'στιγμασ', 'Στιγμασ', 'ΣΤΙΓΜΑΣ', 'στιγμασ', 'στιγμασ', 'στιγμασ',  ],
+[ 'ʀᴀʀᴇ', 'ʀᴀʀᴇ', 'Ʀᴀʀᴇ', 'ƦᴀƦᴇ', 'ʀᴀʀᴇ', 'Ʀᴀʀᴇ', 'ƦᴀƦᴇ', 'ʀᴀʀᴇ', 'ʀᴀʀᴇ', 'ʀᴀʀᴇ',  ],
+[ 'Ʀᴀʀᴇ', 'ʀᴀʀᴇ', 'Ʀᴀʀᴇ', 'ƦᴀƦᴇ', 'ʀᴀʀᴇ', 'Ʀᴀʀᴇ', 'ƦᴀƦᴇ', 'ʀᴀʀᴇ', 'ʀᴀʀᴇ', 'ʀᴀʀᴇ',  ],
+[ 'ƦᴀƦᴇ', 'ʀᴀʀᴇ', 'Ʀᴀʀᴇ', 'ƦᴀƦᴇ', 'ʀᴀʀᴇ', 'Ʀᴀʀᴇ', 'ƦᴀƦᴇ', 'ʀᴀʀᴇ', 'ʀᴀʀᴇ', 'ʀᴀʀᴇ',  ],
+[ 'Ԧԧ', 'ԧԧ', 'Ԧԧ', 'ԦԦ', 'ԧԧ', 'Ԧԧ', 'ԦԦ', 'ԧԧ', 'ԧԧ', 'ԧԧ',  ],
+[ 'ԧԧ', 'ԧԧ', 'Ԧԧ', 'ԦԦ', 'ԧԧ', 'Ԧԧ', 'ԦԦ', 'ԧԧ', 'ԧԧ', 'ԧԧ',  ],
+[ 'Ԧԧ', 'ԧԧ', 'Ԧԧ', 'ԦԦ', 'ԧԧ', 'Ԧԧ', 'ԦԦ', 'ԧԧ', 'ԧԧ', 'ԧԧ',  ],
+[ 'ԦԦ', 'ԧԧ', 'Ԧԧ', 'ԦԦ', 'ԧԧ', 'Ԧԧ', 'ԦԦ', 'ԧԧ', 'ԧԧ', 'ԧԧ',  ],
+[ "þǽr rihtes", "þǽr rihtes", "Þǽr Rihtes", "ÞǼR RIHTES", "þǽr rihtes", "Þǽr Rihtes", "ÞǼR RIHTES", "þǽr rihtes", "þǽr rihtes", "þǽr rihtes",  ],
+[ "duȝeðlice", "duȝeðlice", "Duȝeðlice", "DUȜEÐLICE", "duȝeðlice", "Duȝeðlice", "DUȜEÐLICE", "duȝeðlice", "duȝeðlice", "duȝeðlice",  ],
+[ "Van Dĳke", "van dĳke", "Van Dĳke", "VAN DĲKE", "van dĳke", "Van Dĳke", "VAN DĲKE", "van dĳke", "van dĳke", "van dĳke",  ],
+[ "ﬁ", "ﬁ", "ﬁ", "ﬁ", "ﬁ", "Fi", "FI", "ﬁ", "fi", "fi",  ],
+[ "ﬁlesystem", "ﬁlesystem", "ﬁlesystem", "ﬁLESYSTEM", "ﬁlesystem", "Filesystem", "FILESYSTEM", "ﬁlesystem", "filesystem", "filesystem",  ],
+[ "eﬃcient", "eﬃcient", "Eﬃcient", "EﬃCIENT", "eﬃcient", "Eﬃcient", "EFFICIENT", "eﬃcient", "efficient", "efficient",  ],
+[ "ﬂour and water", "ﬂour and water", "ﬂour And Water", "ﬂOUR AND WATER", "ﬂour and water", "Flour And Water", "FLOUR AND WATER", "ﬂour and water", "flour and water", "flour and water",  ],
+[ "ǳ", "ǳ", "ǲ", "Ǳ", "ǳ", "ǲ", "Ǳ", "ǳ", "ǳ", "ǳ",  ],
+[ "ǳur mountain", "ǳur mountain", "ǲur Mountain", "ǱUR MOUNTAIN", "ǳur mountain", "ǲur Mountain", "ǱUR MOUNTAIN", "ǳur mountain", "ǳur mountain", "ǳur mountain",  ],
+[ "poſt", "poſt", "Poſt", "POST", "poſt", "Poſt", "POST", "post", "post", "post",  ],
+[ "poﬅ", "poﬅ", "Poﬅ", "POﬅ", "poﬅ", "Poﬅ", "POST", "poﬅ", "post", "post",  ],
+[ "ﬅop", "ﬅop", "ﬅop", "ﬅOP", "ﬅop", "Stop", "STOP", "ﬅop", "stop", "stop",  ],
+[ "tschüß", "tschüß", "Tschüß", "TSCHÜß", "tschüß", "Tschüß", "TSCHÜSS", "tschüß", "tschüss", "tschüss",  ],
+[ "TSCHÜẞ", "tschüß", "Tschüß", "TSCHÜẞ", "tschüß", "Tschüß", "TSCHÜẞ", "tschüß", "tschüss", "tschüss",  ],
+[ "rußland", "rußland", "Rußland", "RUßLAND", "rußland", "Rußland", "RUSSLAND", "rußland", "russland", "russland",  ],
+[ "RUẞLAND", "rußland", "Rußland", "RUẞLAND", "rußland", "Rußland", "RUẞLAND", "rußland", "russland", "russland",  ],
+[ "weiß", "weiß", "Weiß", "WEIß", "weiß", "Weiß", "WEISS", "weiß", "weiss", "weiss",  ],
+[ "WEIẞ", "weiß", "Weiß", "WEIẞ", "weiß", "Weiß", "WEIẞ", "weiß", "weıss", "weiss",  ],
+[ "ẞIEW", "ßiew", "ẞiew", "ẞIEW", "ßiew", "ẞiew", "ẞIEW", "ßiew", "ssıew", "ssiew",  ],
+[ "ͅ", "ͅ", "Ι", "Ι", "ͅ", "Ι", "Ι", "ι", "ι", "ι",  ],
+[ "ᾲ", "ᾲ", "Ὰͅ", "ᾺΙ", "ᾲ", "Ὰͅ", "ᾺΙ", "ὰι", "ὰι", "ὰι",  ],
+[ "Ὰι", "ὰι", "Ὰι", "ᾺΙ", "ὰι", "Ὰι", "ᾺΙ", "ὰι", "ὰι", "ὰι",  ],
+[ "ᾺΙ", "ὰι", "Ὰι", "ᾺΙ", "ὰι", "Ὰι", "ᾺΙ", "ὰι", "ὰι", "ὰι",  ],
+[ "ᾲ", "ᾲ", "ᾲ", "ᾲ", "ᾲ", "Ὰͅ", "ᾺΙ", "ᾲ", "ὰι", "ὰι",  ],
+[ "Ὰͅ", "ᾲ", "Ὰͅ", "ᾺΙ", "ᾲ", "Ὰͅ", "ᾺΙ", "ὰι", "ὰι", "ὰι",  ],
+[ "ᾺΙ", "ὰι", "Ὰι", "ᾺΙ", "ὰι", "Ὰι", "ᾺΙ", "ὰι", "ὰι", "ὰι",  ],
+[ "ᾲ στο διάολο", "ᾲ στο διάολο", "ᾲ Στο Διάολο", "ᾲ ΣΤΟ ΔΙΆΟΛΟ", "ᾲ στο διάολο", "Ὰͅ Στο Διάολο", "ᾺΙ ΣΤΟ ΔΙΆΟΛΟ", "ᾲ στο διάολο", "ὰι στο διάολο", "ὰι στο διάολο",  ],
+[ "ᾲ στο διάολο", "ᾲ στο διάολο", "Ὰͅ Στο Διάολο", "ᾺΙ ΣΤΟ ΔΙΆΟΛΟ", "ᾲ στο διάολο", "Ὰͅ Στο Διάολο", "ᾺΙ ΣΤΟ ΔΙΆΟΛΟ", "ὰι στο διάολο", "ὰι στο διάολο", "ὰι στο διάολο",  ],
+[ "ⅷ", "ⅷ", "Ⅷ", "Ⅷ", "ⅷ", "Ⅷ", "Ⅷ", "ⅷ", "ⅷ", "ⅷ",  ],
+[ "henry ⅷ", "henry ⅷ", "Henry Ⅷ", "HENRY Ⅷ", "henry ⅷ", "Henry Ⅷ", "HENRY Ⅷ", "henry ⅷ", "henry ⅷ", "henry ⅷ",  ],
+[ "ⓚ", "ⓚ", "Ⓚ", "Ⓚ", "ⓚ", "Ⓚ", "Ⓚ", "ⓚ", "ⓚ", "ⓚ",  ],
+[ "i work at ⓚ", "i work at ⓚ", "I Work At Ⓚ", "I WORK AT Ⓚ", "i work at ⓚ", "I Work At Ⓚ", "I WORK AT Ⓚ", "i work at ⓚ", "i work at ⓚ", "i work at ⓚ",  ],
+[ "istambul", "istambul", "Istambul", "ISTAMBUL", "istambul", "Istambul", "ISTAMBUL", "istambul", "istambul", "istambul",  ],
+[ "i̇stanbul", "i̇stanbul", "İstanbul", "İSTANBUL", "i̇stanbul", "İstanbul", "İSTANBUL", "i̇stanbul", "i̇stanbul", "i̇stanbul",  ],
+[ "İstanbul", "i̇stanbul", "İstanbul", "İSTANBUL", "i̇stanbul", "İstanbul", "İSTANBUL", "i̇stanbul", "ı̇stanbul", "i̇stanbul",  ],
+[ "İSTANBUL", "istanbul", "İstanbul", "İSTANBUL", "i̇stanbul", "İstanbul", "İSTANBUL", "İstanbul", "istanbul", "i̇stanbul",  ],
+[ "στιγμας", "στιγμας", "Στιγμας", "ΣΤΙΓΜΑΣ", "στιγμας", "Στιγμας", "ΣΤΙΓΜΑΣ", "στιγμασ", "στιγμασ", "στιγμασ",  ],
+[ "στιγμασ", "στιγμασ", "Στιγμασ", "ΣΤΙΓΜΑΣ", "στιγμασ", "Στιγμασ", "ΣΤΙΓΜΑΣ", "στιγμασ", "στιγμασ", "στιγμασ",  ],
+[ "ΣΤΙΓΜΑΣ", "στιγμασ", "Στιγμασ", "ΣΤΙΓΜΑΣ", "στιγμασ", "Στιγμασ", "ΣΤΙΓΜΑΣ", "στιγμασ", "στιγμασ", "στιγμασ",  ],
+[ "ʀᴀʀᴇ", "ʀᴀʀᴇ", "Ʀᴀʀᴇ", "ƦᴀƦᴇ", "ʀᴀʀᴇ", "Ʀᴀʀᴇ", "ƦᴀƦᴇ", "ʀᴀʀᴇ", "ʀᴀʀᴇ", "ʀᴀʀᴇ",  ],
+[ "𐐼𐐯𐑅𐐨𐑉𐐯𐐻", "𐐼𐐯𐑅𐐨𐑉𐐯𐐻", "𐐔𐐯𐑅𐐨𐑉𐐯𐐻", "𐐔𐐇𐐝𐐀𐐡𐐇𐐓", "𐐼𐐯𐑅𐐨𐑉𐐯𐐻", "𐐔𐐯𐑅𐐨𐑉𐐯𐐻", "𐐔𐐇𐐝𐐀𐐡𐐇𐐓", "𐐼𐐯𐑅𐐨𐑉𐐯𐐻", "𐐼𐐯𐑅𐐨𐑉𐐯𐐻", "𐐼𐐯𐑅𐐨𐑉𐐯𐐻",  ],
+[ "Ԧԧ", "ԧԧ", "Ԧԧ", "ԦԦ", "ԧԧ", "Ԧԧ", "ԦԦ", "ԧԧ", "ԧԧ", "ԧԧ",  ],
+[ "ﬓﬔﬕﬖﬗ", "ﬓﬔﬕﬖﬗ", "ﬓﬔﬕﬖﬗ", "ﬓﬔﬕﬖﬗ", "ﬓﬔﬕﬖﬗ", "Մնﬔﬕﬖﬗ", "ՄՆՄԵՄԻՎՆՄԽ", "ﬓﬔﬕﬖﬗ", "մնմեմիվնմխ", "մնմեմիվնմխ",  ],
+[ "ŉ groot", "ŉ groot", "ŉ Groot", "ŉ GROOT", "ŉ groot", "ʼN Groot", "ʼN GROOT", "ŉ groot", "ʼn groot", "ʼn groot",  ],
+[ "ẚ", "ẚ", "ẚ", "ẚ", "ẚ", "Aʾ", "Aʾ", "ẚ", "aʾ", "aʾ",  ],
+[ "ﬀ", "ﬀ", "ﬀ", "ﬀ", "ﬀ", "Ff", "FF", "ﬀ", "ff", "ff",  ],
+[ "ǰ", "ǰ", "ǰ", "ǰ", "ǰ", "J̌", "J̌", "ǰ", "ǰ", "ǰ",  ],
+[ "550 nm or Å", "550 nm or å", "550 Nm Or Å", "550 NM OR Å", "550 nm or å", "550 Nm Or Å", "550 NM OR Å", "550 nm or å", "550 nm or å", "550 nm or å",  ],
+);
+
+    use feature qw(fc);
+
+    for (@test_table) {
+        my ($simple_lc, $simple_tc, $simple_uc, $simple_fc) = @{$_}[1, 2, 3, 7];
+        my ($orig, $lower, $titlecase, $upper, $fc_turkic, $fc_full) = @{$_}[0,4,5,6,8,9];
+
+        is( fc($orig), $fc_full, 'fc works' );
+        is( "\F$orig", $fc_full, '\F works' );
+        is( lc($orig), $lower,   'lc works' );
+        is( "\L$orig", $lower,   '\L works' );
+        is( uc($orig), $upper,   'uc works' );
+        is( "\U$orig", $upper,   '\U works' );
+    }
+}
+
+{
+    use feature qw(fc);
+    package Eeyup  { use overload q{""} => sub { "\x{df}"   }, fallback => 1 }
+    package Uunope { use overload q{""} => sub { "\x{30cb}" }, fallback => 1 }
+    package Undef  { use overload q{""} => sub {   undef    }, fallback => 1 }
+
+    my $obj = bless {}, "Eeyup";
+    is(fc($obj), "ss", "fc() works on overloaded objects returning latin-1");
+    $obj = bless {}, "Eeyup";
+    is("\F$obj", "ss", '\F works on overloaded objects returning latin-1');
+
+    $obj = bless {}, "Uunope";
+    is(fc($obj), "\x{30cb}", "fc() works on overloaded objects returning UTF-8");
+    $obj = bless {}, "Uunope";
+    is("\F$obj", "\x{30cb}", '\F works on overloaded objects returning UTF-8');
+
+    $obj = bless {}, "Undef";
+    my $warnings;
+    {
+        no warnings;
+        use warnings "uninitialized";
+        local $SIG{__WARN__} = sub { $warnings++; like(shift, qr/Use of uninitialized value (?:\$obj )?in fc/) };
+        fc(undef);
+        fc($obj);
+    }
+    is( $warnings, 2, "correct number of warnings" );
+
+    my $fetched = 0;
+    package Derpy { sub TIESCALAR { bless {}, shift } sub FETCH { $fetched++; "\x{df}" } }
+
+    tie my $x, "Derpy";
+
+    is( fc($x), "ss", "fc() works on tied values" );
+    is( $fetched, 1, "and only calls the magic once" );
+
+}
+
+{
+    use feature qw( fc );
+    my $troublesome1 = "\xdf" x 11; #SvLEN should be 12, SvCUR should be 11
+                                    #So this should force fc() to grow the string.
+
+    is( fc($troublesome1), "ss" x 11, "fc() grows the string" );
+
+    my $troublesome2 = "abcdef:\x{df}:fjksjs"; #SvLEN should be 16, SvCUR should be 15
+    is( fc($troublesome2), "abcdef:ss:fjksjs", "fc() expands \\x{DF} in the middle of a string that needs to grow" );
+
+    my $troublesome3 = ":\x{df}:";
+    is( fc($troublesome3), ":ss:", "fc() expands \\x{DF} in the middle of a string" );
+
+
+    my $troublesome4 = "\x{B5}"; #\N{MICRON SIGN} is latin-1, but its foldcase is in UTF-8
+
+    is( fc($troublesome4), "\x{3BC}", "fc() for a latin-1 \x{B5} returns UTF-8" );
+    ok( !utf8::is_utf8($troublesome4), "fc() doesn't upgrade the original string" );
+
+
+    my $troublesome5 = "\x{C9}abda\x{B5}aaf\x{C8}"; # Up until foldcasing \x{B5}, the string
+                                                    # was in Latin-1. This tests that the
+                                                    # results don't have illegal UTF-8
+                                                    # (i.e. leftover latin-1) in them
+
+    is( fc($troublesome5), "\x{E9}abda\x{3BC}aaf\x{E8}" );
+}
+
+{
+    use feature qw( fc unicode_strings );
+
+    # This tests both code paths in pp_fc
+
+    for (0..0xff) {
+        my $latin1 = chr;
+        my $utf8   = $latin1;
+        utf8::downgrade($latin1); #No-op, but doesn't hurt
+        utf8::upgrade($utf8);
+        is(fc($latin1), fc($utf8), "fc() gives the same results for \\x{$_} in Latin-1 and UTF-8 under unicode_strings");
+        {
+            use locale;
+            is(fc($latin1), lc($latin1), "use locale; fc(qq{\\x{$_}}), lc(qq{\\x{$_}}) when qq{\\x{$_}} is in latin-1");
+            is(fc($utf8), lc($utf8), "use locale; fc(qq{\\x{$_}}), lc(qq{\\x{$_}}) when qq{\\x{$_}} is in latin-1");
+        }
+        {
+            no feature 'unicode_strings';
+            is(fc($latin1), lc($latin1), "under nothing, fc() for <256 is the same as lc");
+        }
+    }
+}
+
 my $num_tests = curr_test() - 1;
 
 die qq[$0: failed to find casefoldings from "$CF"\n] unless $num_tests > 0;
diff --git a/toke.c b/toke.c
index 7893eb48f7..bec4b211cf 100644
--- a/toke.c
+++ b/toke.c
@@ -2922,7 +2922,7 @@ S_scan_const(pTHX_ char *start)
 	    }
 
 	    /* string-change backslash escapes */
-	    if (PL_lex_inwhat != OP_TRANS && *s && strchr("lLuUEQ", *s)) {
+	    if (PL_lex_inwhat != OP_TRANS && *s && strchr("lLuUEQF", *s)) {
 		--s;
 		break;
 	    }
@@ -4489,7 +4489,8 @@ Perl_yylex(pTHX)
 		PL_lex_casestack[PL_lex_casemods] = '\0';
 
 		if (PL_bufptr != PL_bufend
-		    && (oldmod == 'L' || oldmod == 'U' || oldmod == 'Q')) {
+		    && (oldmod == 'L' || oldmod == 'U' || oldmod == 'Q'
+                        || oldmod == 'F')) {
 		    PL_bufptr += 2;
 		    PL_lex_state = LEX_INTERPCONCAT;
 #ifdef PERL_MAD
@@ -4539,8 +4540,10 @@ Perl_yylex(pTHX)
 		if (!PL_madskills) /* when just compiling don't need correct */
 		    if (strnEQ(s, "L\\u", 3) || strnEQ(s, "U\\l", 3))
 			tmp = *s, *s = s[2], s[2] = (char)tmp;	/* misordered... */
-		if ((*s == 'L' || *s == 'U') &&
-		    (strchr(PL_lex_casestack, 'L') || strchr(PL_lex_casestack, 'U'))) {
+		if ((*s == 'L' || *s == 'U' || *s == 'F') &&
+		    (strchr(PL_lex_casestack, 'L')
+                        || strchr(PL_lex_casestack, 'U')
+                        || strchr(PL_lex_casestack, 'F'))) {
 		    PL_lex_casestack[--PL_lex_casemods] = '\0';
 		    PL_lex_allbrackets--;
 		    return REPORT(')');
@@ -4564,6 +4567,8 @@ Perl_yylex(pTHX)
 		    NEXTVAL_NEXTTOKE.ival = OP_UC;
 		else if (*s == 'Q')
 		    NEXTVAL_NEXTTOKE.ival = OP_QUOTEMETA;
+                else if (*s == 'F')
+		    NEXTVAL_NEXTTOKE.ival = OP_FC;
 		else
 		    Perl_croak(aTHX_ "panic: yylex, *s=%u", *s);
 		if (PL_madskills) {
@@ -7414,6 +7419,9 @@ Perl_yylex(pTHX)
 	case KEY_fork:
 	    FUN0(OP_FORK);
 
+	case KEY_fc:
+	    UNI(OP_FC);
+
 	case KEY_fcntl:
 	    LOP(OP_FCNTL,XTERM);