use for loop instead of while in SEQUENCE 

This avoids side effects:

   my @abc = ^10; my @ = @abc ... 4; say @abc;

See IRC log for this day.
using binding for better performance

There were concerns about loss of performance with for loop instead of while/shift.  A binding instead of an affectation might help.
Make flipflop smartmatch against $_ instead of calling .Bool.
Add X::Syntax::Regex::SolitaryQuantifier
Add typed exception X::Syntax::Term::MissingInitializer
used for term definitions without initialization assignment (cmp RT #116607)
Speed up Str.trans

It does this by removing matchers that have no chance
of matching again.

JSON::Tiny::to_string uses

$d.trans(['"',  '\\',   "\b", "\f", "\n", "\r", "\t"]
              => ['\"', '\\\\', '\b', '\f', '\n', '\r', '\t'])

With $d = "\n" x 10000, this patch reduces the run time from 13.5s
to 4.9s.
Str.trans: Fix regex context buglet

Previously, Str.trans used substr to extract a substring and then
match a regex against that substring. This messes up all kinds of
zero-width assertions (anchors, word boundaries, look-behinds).

Instead, use the Str.match(Regex, :continue($pos)) to tell the
regex engine where to start
Avoid repeated concatenation (O(n^2)) in Str.trans
Fix build failure, FROGGS++
fix parsing of versions with more than one digit (major-version > 9)

This fixes RT #116016;
Remove :exists/:delete from core settings

We don't need the overhead of :exists/:delete
Make anonymous enums follow Synopsis 2

Adding a pair to an enum is supposed to change the value the next key would get.
Add --git-depth option

The option adds --depth option to all git clone commands
A step towards reliable lazification of @*INC
Don't count lines if we're eager

Just set it at the end
.IO on IO::Path is now a noop for performance
Make IO::Path.new(:directory) work (again)

It's all in which the candidates are listed.
No longer use IO::Path.all internally

It is under investigation
Fix scoping issue in IO::Path.all
Make sure $!ins is up to date, pmichaud++