=item *
-XXX
+The rather slow implementation for the experimental subroutine signatures
+feature has been made much faster; it is now comparable in speed with the
+old-style C<my ($a, $b, @c) = @_>.
=back
=item *
-XXX
+Three new ops, C<OP_ARGELEM>, C<OP_ARGDEFELEM> and C<OP_ARGCHECK> have
+been added. These are intended principally to implement the individual
+elements of a subroutine signature, plus any overall checking required.
=back
=item *
-XXX
+Problems with in-place array sorts: code like C<@a = sort { ... } @a>,
+where the source and destination of the sort are the same plain array, are
+optimised to do less copying around. Two side-effects of this optimisation
+were that the contents of C<@a> as visible to to sort routine were
+partially sorted, and under some circumstances accessing C<@a> during the
+sort could crash the interpreter. Both these issues have been fixed, and
+Sort functions see the original value of C<@a>.
+
+=item *
+
+Non-ASCII string delimiters are now reported correctly in error messages
+for unterminated strings. [perl #128701]
+
+=item *
+
+C<pack("p", ...)> used to emit its warning ("Attempt to pack pointer to
+temporary value") erroneously in some cases, but has been fixed.
+
+=item *
+
+C<@DB::args> is now exempt from "used once" warnings. The warnings only
+occurred under B<-w>, because F<warnings.pm> itself uses C<@DB::args>
+multiple times.
+
+=item *
+
+The use of built-in arrays or hash slices in a double-quoted string no
+longer issues a warning ("Possible unintended interpolation...") if the
+variable has not been mentioned before. This affected code like
+C<qq|@DB::args|> and C<qq|@SIG{'CHLD', 'HUP'}|>. (The special variables
+C<@-> and C<@+> were already exempt from the warning.)
+
+=item *
+
+C<gethostent> and similar functions now perform a null check internally, to
+avoid crashing with torsocks. This was a regression from 5.22. [perl
+#128740]
+
+=item *
+
+C<defined *{'!'}>, C<defined *{'['}>, and C<defined *{'-'}> no longer leak
+memory if the typeglob in question has never been accessed before.
+
+=item *
+
+In 5.25.4 fchown() was changed not to accept negative one as an argument
+because in some platforms that is an error. However, in some other platforms
+that is an acceptable argument. This change has been reverted [perl #128967].
+
+=item *
+
+Mentioning the same constant twice in a row (which is a syntax error) no
+longer fails an assertion under debugging builds. This was a regression
+from 5.20. [perl #126482]
+
+=item *
+
+Many issues relating to C<printf "%a"> of hexadecimal floating point
+were fixed. In addition, the "subnormals" (formerly known as "denormals")
+floating point anumbers are now supported both with the plain IEEE 754
+floating point numbers (64-bit or 128-bit) and the x86 80-bit
+"extended precision". Note that subnormal hexadecimal floating
+point literals will give a warning about "exponent underflow".
+[perl #128843, #128889, #128890, #128893, #128909, #128919]
+
+=item *
+
+A regression in 5.24 with C<tr/\N{U+...}/foo/> when the code point was between
+128 and 255 has been fixed. [perl #128734].
+
+=item *
+
+A regression from the previous development release, 5.23.3, where
+compiling a regular expression could crash the interpreter has been
+fixed. [perl #128686].
+
+=item *
+
+Use of a string delimiter whose code point is above 2**31 now works
+correctly on platforms that allow this. Previously, certain characters,
+due to truncation, would be confused with other delimiter characters
+with special meaning (such as C<?> in C<m?...?>), resulting
+in inconsistent behaviour. Note that this is non-portable,
+and is based on Perl's extension to UTF-8, and is probably not
+displayable nor enterable by any editor. [perl #128738]
=back