Perl

Unicode 12.1 is supported

The upper limit n specifiable in a regular expression quantifier of the form {m,n}` has been doubled to 65534

Wildcards in Unicode property value specifications are now partially supported

qr'\N{name}' is now supported

It is now possible to compile perl to always use thread-safe locale operations

Limited variable length lookbehind in regular expression pattern matching is now experimentally supported

Use faster method to convert to UTF-8

Turkic UTF-8 locales are now seamlessly supported

Eliminate opASSIGN macro usage from core

-Drv now means something on -DDEBUGGING builds

Removed modules: Math::BigInt::CalcEmu, arybase, Locale::Code, B::Debug

Pattern delimiters now must be graphemes

Delimiters must now be graphemes

Some formerly deprecated uses of an unescaped left brace { in regular expression patterns are now illegal

Assigning non-zero to $[ is fatal

Previously deprecated sysread()/syswrite() on :utf8 handles now fatal

my() in false conditional prohibited

Fatalize $* and $#

Fatalize unqualified use of dump()

Remove File::Glob::glob()

pack() no longer can return malformed UTF-8

Any set of digits in the Common script are legal in a script run of another script

JSON::PP enable allow_nonref by default

Site paths moved from /usr/local/…/perl5 to /usr/local/…/perl5/5.30

In XS code, use of various macros dealing with UTF-8.