In perl.git, the branch maint-5.28 has been updated

<https://perl5.git.perl.org/perl.git/commitdiff/94027dc85b896cfea4bd017b273f22e472882d68?hp=7346c5fcf961df288bd249d2f150ab6f0e40a3ee>

- Log -----------------------------------------------------------------
commit 94027dc85b896cfea4bd017b273f22e472882d68
Author: Steve Hay <steve.m....@googlemail.com>
Date:   Sun Nov 4 22:12:12 2018 +0000

    Fix-ups to previous cherry-pick
    
    (For blead this was done in b0394755dd.)

commit 9d1ba25688d286786d0994b12f4a84b76cfdcf36
Author: Sawyer X <xsawy...@cpan.org>
Date:   Fri Jun 22 20:19:08 2018 -0600

    Add per5280delta.pod to MANIFEST
    
    (cherry picked from commit 8a466a496bec7250920063d8f0eb252b0d962c08)

-----------------------------------------------------------------------

Summary of changes:
 MANIFEST                                 |    1 +
 Makefile.SH                              |    8 +-
 pod/.gitignore                           |    2 +-
 pod/perl.pod                             |    1 +
 pod/{perldelta.pod => perl5280delta.pod} |    2 +-
 pod/perldelta.pod                        | 2398 +++---------------------------
 vms/descrip_mms.template                 |    2 +-
 win32/GNUmakefile                        |    4 +-
 win32/Makefile                           |    4 +-
 win32/makefile.mk                        |    4 +-
 win32/pod.mak                            |    4 +
 11 files changed, 221 insertions(+), 2209 deletions(-)
 copy pod/{perldelta.pod => perl5280delta.pod} (99%)

diff --git a/MANIFEST b/MANIFEST
index 2005f544cd..fcf3455b2e 100644
--- a/MANIFEST
+++ b/MANIFEST
@@ -5068,6 +5068,7 @@ pod/perl5244delta.pod             Perl changes in version 
5.24.4
 pod/perl5260delta.pod          Perl changes in version 5.26.0
 pod/perl5261delta.pod          Perl changes in version 5.26.1
 pod/perl5262delta.pod          Perl changes in version 5.26.2
+pod/perl5280delta.pod          Perl changes in version 5.28.0
 pod/perl561delta.pod           Perl changes in version 5.6.1
 pod/perl56delta.pod            Perl changes in version 5.6
 pod/perl581delta.pod           Perl changes in version 5.8.1
diff --git a/Makefile.SH b/Makefile.SH
index 123903dcb0..5197009290 100755
--- a/Makefile.SH
+++ b/Makefile.SH
@@ -575,7 +575,7 @@ esac
 
 $spitshell >>$Makefile <<'!NO!SUBS!'
 
-perltoc_pod_prereqs = extra.pods pod/perl5280delta.pod pod/perlapi.pod 
pod/perlintern.pod pod/perlmodlib.pod pod/perluniprops.pod
+perltoc_pod_prereqs = extra.pods pod/perl5281delta.pod pod/perlapi.pod 
pod/perlintern.pod pod/perlmodlib.pod pod/perluniprops.pod
 generated_pods = pod/perltoc.pod $(perltoc_pod_prereqs)
 generated_headers = uudmap.h bitcount.h mg_data.h
 
@@ -1125,9 +1125,9 @@ pod/perlintern.pod: $(MINIPERL_EXE) autodoc.pl embed.fnc
 pod/perlmodlib.pod: $(MINIPERL_EXE) pod/perlmodlib.PL MANIFEST
        $(MINIPERL) pod/perlmodlib.PL -q
 
-pod/perl5280delta.pod: pod/perldelta.pod
-       $(RMS) pod/perl5280delta.pod
-       $(LNS) perldelta.pod pod/perl5280delta.pod
+pod/perl5281delta.pod: pod/perldelta.pod
+       $(RMS) pod/perl5281delta.pod
+       $(LNS) perldelta.pod pod/perl5281delta.pod
 
 extra.pods: $(MINIPERL_EXE)
        -@test ! -f extra.pods || rm -f `cat extra.pods`
diff --git a/pod/.gitignore b/pod/.gitignore
index 8974e374d6..26160694da 100644
--- a/pod/.gitignore
+++ b/pod/.gitignore
@@ -50,7 +50,7 @@
 /roffitall
 
 # generated
-/perl5280delta.pod
+/perl5281delta.pod
 /perlapi.pod
 /perlintern.pod
 /perlmodlib.pod
diff --git a/pod/perl.pod b/pod/perl.pod
index 15c6b4427d..fbbb952b6b 100644
--- a/pod/perl.pod
+++ b/pod/perl.pod
@@ -181,6 +181,7 @@ aux h2ph h2xs perlbug pl2pm pod2html pod2man splain xsubpp
 
     perlhist           Perl history records
     perldelta          Perl changes since previous version
+    perl5280delta      Perl changes in version 5.28.0
     perl5262delta      Perl changes in version 5.26.2
     perl5261delta      Perl changes in version 5.26.1
     perl5260delta      Perl changes in version 5.26.0
diff --git a/pod/perldelta.pod b/pod/perl5280delta.pod
similarity index 99%
copy from pod/perldelta.pod
copy to pod/perl5280delta.pod
index f823fbf6a6..0ecd260ca5 100644
--- a/pod/perldelta.pod
+++ b/pod/perl5280delta.pod
@@ -2,7 +2,7 @@
 
 =head1 NAME
 
-perldelta - what is new for perl v5.28.0
+perl5280delta - what is new for perl v5.28.0
 
 =head1 DESCRIPTION
 
diff --git a/pod/perldelta.pod b/pod/perldelta.pod
index f823fbf6a6..d5ebc3ab1d 100644
--- a/pod/perldelta.pod
+++ b/pod/perldelta.pod
@@ -2,423 +2,57 @@
 
 =head1 NAME
 
-perldelta - what is new for perl v5.28.0
+[ this is a template for a new perldelta file.  Any text flagged as XXX needs
+to be processed before release. ]
+
+perldelta - what is new for perl v5.28.1
 
 =head1 DESCRIPTION
 
-This document describes differences between the 5.26.0 release and the 5.28.0
+This document describes differences between the 5.28.0 release and the 5.28.1
 release.
 
-If you are upgrading from an earlier release such as 5.24.0, first read
-L<perl5260delta>, which describes differences between 5.24.0 and 5.26.0.
-
-=head1 Core Enhancements
-
-=head2 Unicode 10.0 is supported
-
-A list of changes is at
-L<http://www.unicode.org/versions/Unicode10.0.0>.
-
-=head2 L<C<delete>|perlfunc/delete EXPR> on key/value hash slices
-
-L<C<delete>|perlfunc/delete EXPR> can now be used on
-L<keyE<sol>value hash slices|perldata/KeyE<sol>Value Hash Slices>,
-returning the keys along with the deleted values.
-L<[perl #131328]|https://rt.perl.org/Ticket/Display.html?id=131328>
-
-=head2 Experimentally, there are now alphabetic synonyms for some regular 
expression assertions
-
-If you find it difficult to remember how to write certain of the pattern
-assertions, there are now alphabetic synonyms.
-
- CURRENT                NEW SYNONYMS
- ------                 ------------
- (?=...)        (*pla:...) or (*positive_lookahead:...)
- (?!...)        (*nla:...) or (*negative_lookahead:...)
- (?<=...)       (*plb:...) or (*positive_lookbehind:...)
- (?<!...)       (*nlb:...) or (*negative_lookbehind:...)
- (?>...)        (*atomic:...)
-
-These are considered experimental, so using any of these will raise
-(unless turned off) a warning in the C<experimental::alpha_assertions>
-category.
-
-=head2 Mixed Unicode scripts are now detectable
-
-A mixture of scripts, such as Cyrillic and Latin, in a string is often
-the sign of a spoofing attack.  A new regular expression construct
-now allows for easy detection of these.  For example, you can say
-
- qr/(*script_run: \d+ \b )/x
-
-And the digits matched will all be from the same set of 10.  You won't
-get a look-alike digit from a different script that has a different
-value than what it appears to be.
-
-Or:
-
- qr/(*sr: \b \w+ \b )/x
-
-makes sure that all the characters come from the same script.
-
-You can also combine script runs with C<(?E<gt>...)> (or
-C<*atomic:...)>).
-
-Instead of writing:
-
-    (*sr:(?<...))
-
-you can now run:
-
-    (*asr:...)
-    # or
-    (*atomic_script_run:...)
-
-This is considered experimental, so using it will raise (unless turned
-off) a warning in the C<experimental::script_run> category.
-
-See L<perlre/Script Runs>.
-
-=head2 In-place editing with C<perl -i> is now safer
-
-Previously in-place editing (C<perl -i>) would delete or rename the
-input file as soon as you started working on a new file.
-
-Without backups this would result in loss of data if there was an
-error, such as a full disk, when writing to the output file.
-
-This has changed so that the input file isn't replaced until the
-output file has been completely written and successfully closed.
-
-This works by creating a work file in the same directory, which is
-renamed over the input file once the output file is complete.
-
-Incompatibilities:
-
-=over
-
-=item *
-
-Since this renaming needs to only happen once, if you create a thread
-or child process, that renaming will only happen in the original
-thread or process.
-
-=item *
-
-If you change directories while processing a file, and your operating
-system doesn't provide the C<unlinkat()>, C<renameat()> and C<fchmodat()>
-functions, the final rename step may fail.
-
-=back
-
-L<[perl #127663]|https://rt.perl.org/Public/Bug/Display.html?id=127663>
-
-=head2 Initialisation of aggregate state variables
-
-A persistent lexical array or hash variable can now be initialized,
-by an expression such as C<state @a = qw(x y z)>.  Initialization of a
-list of persistent lexical variables is still not possible.
-
-=head2 Full-size inode numbers
-
-On platforms where inode numbers are of a type larger than perl's native
-integer numerical types, L<stat|perlfunc/stat> will preserve the full
-content of large inode numbers by returning them in the form of strings of
-decimal digits.  Exact comparison of inode numbers can thus be achieved by
-comparing with C<eq> rather than C<==>.  Comparison with C<==>, and other
-numerical operations (which are usually meaningless on inode numbers),
-work as well as they did before, which is to say they fall back to
-floating point, and ultimately operate on a fairly useless rounded inode
-number if the real inode number is too big for the floating point format.
-
-=head2 The C<sprintf> C<%j> format size modifier is now available with pre-C99 
compilers
-
-The actual size used depends on the platform, so remains unportable.
+If you are upgrading from an earlier release such as 5.27.0, first read
+L<perl5280delta>, which describes differences between 5.27.0 and 5.28.0.
 
-=head2 Close-on-exec flag set atomically
+=head1 Notice
 
-When opening a file descriptor, perl now generally opens it with its
-close-on-exec flag already set, on platforms that support doing so.
-This improves thread safety, because it means that an C<exec> initiated
-by one thread can no longer cause a file descriptor in the process
-of being opened by another thread to be accidentally passed to the
-executed program.
+XXX Any important notices here
 
-Additionally, perl now sets the close-on-exec flag more reliably, whether
-it does so atomically or not.  Most file descriptors were getting the
-flag set, but some were being missed.
-
-=head2 String- and number-specific bitwise ops are no longer experimental
-
-The new string-specific (C<&. |. ^. ~.>) and number-specific (C<& | ^ ~>)
-bitwise operators introduced in Perl 5.22 that are available within the
-scope of C<use feature 'bitwise'> are no longer experimental.
-Because the number-specific ops are spelled the same way as the existing
-operators that choose their behaviour based on their operands, these
-operators must still be enabled via the "bitwise" feature, in either of
-these two ways:
-
-    use feature "bitwise";
-
-    use v5.28; # "bitwise" now included
-
-They are also now enabled by the B<-E> command-line switch.
-
-The "bitwise" feature no longer emits a warning.  Existing code that
-disables the "experimental::bitwise" warning category that the feature
-previously used will continue to work.
-
-One caveat that module authors ought to be aware of is that the numeric
-operators now pass a fifth TRUE argument to overload methods.  Any methods
-that check the number of operands may croak if they do not expect so many.
-XS authors in particular should be aware that this:
-
-    SV *
-    bitop_handler (lobj, robj, swap)
-
-may need to be changed to this:
-
-    SV *
-    bitop_handler (lobj, robj, swap, ...)
-
-=head2 Locales are now thread-safe on systems that support them
-
-These systems include Windows starting with Visual Studio 2005, and in
-POSIX 2008 systems.
-
-The implication is that you are now free to use locales and change them
-in a threaded environment.  Your changes affect only your thread.
-See L<perllocale/Multi-threaded operation>
+=head1 Core Enhancements
 
-=head2 New read-only predefined variable C<${^SAFE_LOCALES}>
+XXX New core language features go here.  Summarize user-visible core language
+enhancements.  Particularly prominent performance optimisations could go
+here, but most should go in the L</Performance Enhancements> section.
 
-This variable is 1 if the Perl interpreter is operating in an
-environment where it is safe to use and change locales (see
-L<perllocale>.)  This variable is true when the perl is
-unthreaded, or compiled in a platform that supports thread-safe locale
-operation (see previous item).
+[ List each enhancement as a =head2 entry ]
 
 =head1 Security
 
-=head2 [CVE-2017-12837] Heap buffer overflow in regular expression compiler
-
-Compiling certain regular expression patterns with the case-insensitive
-modifier could cause a heap buffer overflow and crash perl.  This has now been
-fixed.
-L<[perl #131582]|https://rt.perl.org/Public/Bug/Display.html?id=131582>
-
-=head2 [CVE-2017-12883] Buffer over-read in regular expression parser
+XXX Any security-related notices go here.  In particular, any security
+vulnerabilities closed should be noted here rather than in the
+L</Selected Bug Fixes> section.
 
-For certain types of syntax error in a regular expression pattern, the error
-message could either contain the contents of a random, possibly large, chunk of
-memory, or could crash perl.  This has now been fixed.
-L<[perl #131598]|https://rt.perl.org/Public/Bug/Display.html?id=131598>
-
-=head2 [CVE-2017-12814] C<$ENV{$key}> stack buffer overflow on Windows
-
-A possible stack buffer overflow in the C<%ENV> code on Windows has been fixed
-by removing the buffer completely since it was superfluous anyway.
-L<[perl #131665]|https://rt.perl.org/Public/Bug/Display.html?id=131665>
-
-=head2 Default Hash Function Change
-
-Perl 5.28.0 retires various older hash functions which are not viewed as
-sufficiently secure for use in Perl. We now support four general purpose
-hash functions, Siphash (2-4 and 1-3 variants), and  Zaphod32, and StadtX
-hash. In addition we support SBOX32 (a form of tabular hashing) for hashing
-short strings, in conjunction with any of the other hash functions provided.
-
-By default Perl is configured to support SBOX hashing of strings up to 24
-characters, in conjunction with StadtX hashing on 64 bit builds, and
-Zaphod32 hashing for 32 bit builds.
-
-You may control these settings with the following options to Configure:
-
-    -DPERL_HASH_FUNC_SIPHASH
-    -DPERL_HASH_FUNC_SIPHASH13
-    -DPERL_HASH_FUNC_STADTX
-    -DPERL_HASH_FUNC_ZAPHOD32
-
-To disable SBOX hashing you can use
-
-    -DPERL_HASH_USE_SBOX32_ALSO=0
-
-And to set the maximum length to use SBOX32 hashing on with:
-
-    -DSBOX32_MAX_LEN=16
-
-The maximum length allowed is 256. There probably isn't much point
-in setting it higher than the default.
+[ List each security issue as a =head2 entry ]
 
 =head1 Incompatible Changes
 
-=head2 Subroutine attribute and signature order
-
-The experimental subroutine signatures feature has been changed so that
-subroutine attributes must now come before the signature rather than
-after. This is because attributes like C<:lvalue> can affect the
-compilation of code within the signature, for example:
-
-    sub f :lvalue ($a = do { $x = "abc"; return substr($x,0,1)}) { ...}
-
-Note that this the second time they have been flipped:
-
-    sub f :lvalue ($a, $b) { ... }; # 5.20; 5.28 onwards
-    sub f ($a, $b) :lvalue { ... }; # 5.22 - 5.26
-
-=head2 Comma-less variable lists in formats are no longer allowed
-
-Omitting the commas between variables passed to formats is no longer
-allowed.  This has been deprecated since Perl 5.000.
-
-=head2 The C<:locked> and C<:unique> attributes have been removed
-
-These have been no-ops and deprecated since Perl 5.12 and 5.10,
-respectively.
-
-=head2 C<\N{}> with nothing between the braces is now illegal
-
-This has been deprecated since Perl 5.24.
-
-=head2 Opening the same symbol as both a file and directory handle is no 
longer allowed
-
-Using C<open()> and C<opendir()> to associate both a filehandle and a dirhandle
-to the same symbol (glob or scalar) has been deprecated since Perl 5.10.
-
-=head2 Use of bare C<< << >> to mean C<< <<"" >> is no longer allowed
-
-Use of a bare terminator has been deprecated since Perl 5.000.
-
-=head2 Setting $/ to a reference to a non-positive integer no longer allowed
-
-This used to work like setting it to C<undef>, but has been deprecated
-since Perl 5.20.
-
-=head2 Unicode code points with values exceeding C<IV_MAX> are now fatal
-
-This was deprecated since Perl 5.24.
-
-=head2 The C<B::OP::terse> method has been removed
-
-Use C<B::Concise::b_terse> instead.
+XXX For a release on a stable branch, this section aspires to be:
 
-=head2 Use of inherited AUTOLOAD for non-methods is no longer allowed
+    There are no changes intentionally incompatible with 5.XXX.XXX
+    If any exist, they are bugs, and we request that you submit a
+    report.  See L</Reporting Bugs> below.
 
-This was deprecated in Perl 5.004.
-
-=head2 Use of strings with code points over 0xFF is not allowed for bitwise 
string operators
-
-Code points over C<0xFF> do not make sense for bitwise operators and such
-an operation will now croak, except for a few remaining cases. See
-L<perldeprecation>.
-
-This was deprecated in Perl 5.24.
-
-=head2 Setting C<${^ENCODING}> to a defined value is now illegal
-
-This has been deprecated since Perl 5.22 and a no-op since Perl 5.26.
-
-=head2 Backslash no longer escapes colon in PATH for the C<-S> switch
-
-Previously the C<-S> switch incorrectly treated backslash ("\") as an
-escape for colon when traversing the C<PATH> environment variable.
-L<[perl #129183]|https://rt.perl.org/Ticket/Display.html?id=129183>
-
-=head2 the -DH (DEBUG_H) misfeature has been removed
-
-On a perl built with debugging support, the C<H> flag to the C<-D>
-debugging option has been removed. This was supposed to dump hash values,
-but has been broken for many years.
-
-=head2 Yada-yada is now strictly a statement
-
-By the time of its initial stable release in Perl 5.12, the C<...>
-(yada-yada) operator was explicitly intended to serve as a statement,
-not an expression.  However, the original implementation was confused
-on this point, leading to inconsistent parsing.  The operator was
-accidentally accepted in a few situations where it did not serve as a
-complete statement, such as
-
-    ... . "foo";
-    ... if $a < $b;
-
-The parsing has now been made consistent, permitting yada-yada only as
-a statement.  Affected code can use C<do{...}> to put a yada-yada into
-an arbitrary expression context.
-
-=head2 Sort algorithm can no longer be specified
-
-Since Perl 5.8, the L<sort> pragma has had subpragmata C<_mergesort>,
-C<_quicksort>, and C<_qsort> that can be used to specify which algorithm
-perl should use to implement the L<sort|perlfunc/sort> builtin.
-This was always considered a dubious feature that might not last,
-hence the underscore spellings, and they were documented as not being
-portable beyond Perl 5.8.  These subpragmata have now been deleted,
-and any attempt to use them is an error.  The L<sort> pragma otherwise
-remains, and the algorithm-neutral C<stable> subpragma can be used to
-control sorting behaviour.
-L<[perl #119635]|https://rt.perl.org/Ticket/Display.html?id=119635>
-
-=head2 Over-radix digits in floating point literals
-
-Octal and binary floating point literals used to permit any hexadecimal
-digit to appear after the radix point.  The digits are now restricted
-to those appropriate for the radix, as digits before the radix point
-always were.
-
-=head2 Return type of C<unpackstring()>
-
-The return types of the C API functions C<unpackstring()> and
-C<unpack_str()> have changed from C<I32> to C<SSize_t>, in order to
-accommodate datasets of more than two billion items.
+[ List each incompatible change as a =head2 entry ]
 
 =head1 Deprecations
 
-=head2 Use of L<C<vec>|perlfunc/vec EXPR,OFFSET,BITS> on strings with code 
points above 0xFF is deprecated
-
-Such strings are represented internally in UTF-8, and C<vec> is a
-bit-oriented operation that will likely give unexpected results on those
-strings.
-
-=head2 Some uses of unescaped C<"{"> in regexes are no longer fatal
-
-Perl 5.26.0 fatalized some uses of an unescaped left brace, but an
-exception was made at the last minute, specifically crafted to be a
-minimal change to allow GNU Autoconf to work.  That tool is heavily
-depended upon, and continues to use the deprecated usage.  Its use of an
-unescaped left brace is one where we have no intention of repurposing
-C<"{"> to be something other than itself.
-
-That exception is now generalized to include various other such cases
-where the C<"{"> will not be repurposed. 
-
-Note that these uses continue to raise a deprecation message.
-
-=head2 Use of unescaped C<"{"> immediately after a C<"("> in regular 
expression patterns is deprecated
-
-Using unescaped left braces is officially deprecated everywhere, but it
-is not enforced in contexts where their use does not interfere with
-expected extensions to the language.  A deprecation is added in this
-release when the brace appears immediately after an opening parenthesis.
-Before this, even if the brace was part of a legal quantifier, it was
-not interpreted as such, but as the literal characters, unlike other
-quantifiers that follow a C<"("> which are considered errors.  Now,
-their use will raise a deprecation message, unless turned off.
-
-=head2 Assignment to C<$[> will be fatal in Perl 5.30
-
-Assigning a non-zero value to L<C<$[>|perlvar/$[> has been deprecated
-since Perl 5.12, but was never given a deadline for removal.  This has
-now been scheduled for Perl 5.30.
-
-=head2 hostname() won't accept arguments in Perl 5.32
-
-Passing arguments to C<Sys::Hostname::hostname()> was already deprecated,
-but didn't have a removal date.  This has now been scheduled for Perl
-5.32.  L<[perl #124349]|https://rt.perl.org/Ticket/Display.html?id=124349>
+XXX Any deprecated features, syntax, modules etc. should be listed here.
 
 =head2 Module removals
 
+XXX Remove this section if not applicable.
+
 The following modules will be removed from the core distribution in a
 future release, and will at that time need to be installed from CPAN.
 Distributions on CPAN which require these modules will need to list them as
@@ -435,1969 +69,341 @@ not usually on concerns over their design.
 
 =over
 
-=item B::Debug
+=item XXX
 
-=item L<Locale::Codes> and its associated Country, Currency and Language 
modules
+XXX Note that deprecated modules should be listed here even if they are listed
+as an updated module in the L</Modules and Pragmata> section.
 
 =back
 
-=head1 Performance Enhancements
-
-=over 4
-
-=item *
-
-The start up overhead for creating regular expression patterns with
-Unicode properties (C<\p{...}>) has been greatly reduced in most cases.
-
-=item *
-
-Many string concatenation expressions are now considerably faster, due
-to the introduction internally of a C<multiconcat> opcode which combines
-multiple concatenations, and optionally a C<=> or C<.=>, into a single
-action. For example, apart from retrieving C<$s>, C<$a> and C<$b>, this
-whole expression is now handled as a single op:
+[ List each other deprecation as a =head2 entry ]
 
-    $s .= "a=$a b=$b\n"
-
-As a special case, if the LHS of an assignment is a lexical variable or
-C<my $s>, the op itself handles retrieving the lexical variable, which
-is faster.
-
-In general, the more the expression includes a mix of constant strings and
-variable expressions, the longer the expression, and the more it mixes
-together non-utf8 and utf8 strings, the more marked the performance
-improvement. For example on a C<x86_64> system, this code has been
-benchmarked running four times faster:
-
-    my $s;
-    my $a = "ab\x{100}cde";
-    my $b = "fghij";
-    my $c = "\x{101}klmn";
-
-    for my $i (1..10_000_000) {
-        $s = "\x{100}wxyz";
-        $s .= "foo=$a bar=$b baz=$c";
-    }
+=head1 Performance Enhancements
 
-In addition, C<sprintf> expressions which have a constant format
-containing only C<%s> and C<%%> format elements, and which have a fixed
-number of arguments, are now also optimised into a C<multiconcat> op.
+XXX Changes which enhance performance without changing behaviour go here.
+There may well be none in a stable release.
 
-=item *
+[ List each enhancement as an =item entry ]
 
-The C<ref()> builtin is now much faster in boolean context, since it no
-longer bothers to construct a temporary string like C<Foo=ARRAY(0x134af48)>.
+=over 4
 
 =item *
 
-C<keys()> in void and scalar contexts is now more efficient.
+XXX
 
-=item *
+=back
 
-The common idiom of comparing the result of index() with -1 is now
-specifically optimised,  e.g.
+=head1 Modules and Pragmata
 
-    if (index(...) != -1) { ... }
+XXX All changes to installed files in F<cpan/>, F<dist/>, F<ext/> and F<lib/>
+go here.  If Module::CoreList is updated, generate an initial draft of the
+following sections using F<Porting/corelist-perldelta.pl>.  A paragraph summary
+for important changes should then be added by hand.  In an ideal world,
+dual-life modules would have a F<Changes> file that could be cribbed.
 
-=item *
+The list of new and updated modules is modified automatically as part of
+preparing a Perl release, so the only reason to manually add entries here is if
+you're summarising the important changes in the module update. (Also, if the
+manually-added details don't match the automatically-generated ones, the
+release manager will have to investigate the situation carefully.)
 
-C<for()> loops and similar constructs are now more efficient in most cases.
+[ Within each section, list entries as an =item entry ]
 
-=item *
+=head2 New Modules and Pragmata
 
-L<File::Glob> has been modified to remove unnecessary backtracking and
-recursion, thanks to Russ Cox. See L<https://research.swtch.com/glob>
-for more details.
+=over 4
 
 =item *
 
-The XS-level C<SvTRUE()> API function is now more efficient.
-
-=item *
+XXX Remove this section if not applicable.
 
-Various integer-returning ops are now more efficient in scalar/boolean context.
+=back
 
-=item *
+=head2 Updated Modules and Pragmata
 
-Slightly improved performance when parsing stash names.
-L<[perl #129990]|https://rt.perl.org/Public/Bug/Display.html?id=129990>
+=over 4
 
 =item *
 
-Calls to C<require> for an already loaded module are now slightly faster.
-L<[perl #132171]|https://rt.perl.org/Public/Bug/Display.html?id=132171>
+L<XXX> has been upgraded from version A.xx to B.yy.
 
-=item *
+If there was something important to note about this change, include that here.
 
-The performance of pattern matching C<[[:ascii:]]> and C<[[:^ascii:]]>
-has been improved significantly except on EBCDIC platforms.
+=back
 
-=item *
+=head2 Removed Modules and Pragmata
 
-Various optimizations have been applied to matching regular expression
-patterns, so under the right circumstances, significant performance
-gains may be noticed.  But in an application with many varied patterns,
-little overall improvement likely will be seen.
+=over 4
 
 =item *
 
-Other optimizations have been applied to UTF-8 handling, but these are
-not typically a major factor in most applications.
+XXX
 
 =back
 
-=head1 Modules and Pragmata
+=head1 Documentation
 
-Key highlights in this release across several modules:
+XXX Changes to files in F<pod/> go here.  Consider grouping entries by
+file and be sure to link to the appropriate page, e.g. L<perlfunc>.
 
-=head2 Removal of use vars
+=head2 New Documentation
 
-The usage of C<use vars> has been discouraged since the introduction of
-C<our> in Perl 5.6.0. Where possible the usage of this pragma has now been
-removed from the Perl source code.
+XXX Changes which create B<new> files in F<pod/> go here.
 
-This had a slight effect (for the better) on the output of WARNING_BITS in
-L<B::Deparse>.
+=head3 L<XXX>
 
-=head2 Use of DynaLoader changed to XSLoader in many modules
+XXX Description of the purpose of the new file here
 
-XSLoader is more modern, and most modules already require perl 5.6 or
-greater, so no functionality is lost by switching. In some cases, we have
-also made changes to the local implementation that may not be reflected in
-the version on CPAN due to a desire to maintain more backwards
-compatibility.
+=head2 Changes to Existing Documentation
 
-=head2 Updated Modules and Pragmata
+We have attempted to update the documentation to reflect the changes
+listed in this document.  If you find any we have missed, send email
+to L<perl...@perl.org|mailto:perl...@perl.org>.
 
-=over 4
+XXX Changes which significantly change existing files in F<pod/> go here.
+However, any changes to F<pod/perldiag.pod> should go in the L</Diagnostics>
+section.
 
-=item *
+Additionally, the following selected changes have been made:
 
-L<Archive::Tar> has been upgraded from version 2.24 to 2.30.
+=head3 L<XXX>
 
-This update also handled CVE-2018-12015: directory traversal
-vulnerability.
-L<[cpan #125523]|https://rt.cpan.org/Ticket/Display.html?id=125523>
+=over 4
 
 =item *
 
-L<arybase> has been upgraded from version 0.12 to 0.15.
+XXX Description of the change here
 
-=item *
+=back
 
-L<Attribute::Handlers> has been upgraded from version 0.99 to 1.01.
+=head1 Diagnostics
 
-=item *
+The following additions or changes have been made to diagnostic output,
+including warnings and fatal error messages.  For the complete list of
+diagnostic messages, see L<perldiag>.
 
-L<attributes> has been upgraded from version 0.29 to 0.33.
+XXX New or changed warnings emitted by the core's C<C> code go here.  Also
+include any changes in L<perldiag> that reconcile it to the C<C> code.
 
-=item *
+=head2 New Diagnostics
 
-L<B> has been upgraded from version 1.68 to 1.74.
+XXX Newly added diagnostic messages go under here, separated into New Errors
+and New Warnings
 
-=item *
+=head3 New Errors
 
-L<B::Concise> has been upgraded from version 0.999 to 1.003.
+=over 4
 
 =item *
 
-L<B::Debug> has been upgraded from version 1.24 to 1.26.
-
-NOTE: L<B::Debug> is deprecated and may be removed from a future version
-of Perl.
+XXX L<message|perldiag/"message">
 
-=item *
-
-L<B::Deparse> has been upgraded from version 1.40 to 1.48.
+=back
 
-It includes many bug fixes, and in particular, it now deparses variable
-attributes correctly:
+=head3 New Warnings
 
-    my $x :foo;  # used to deparse as
-                 # 'attributes'->import('main', \$x, 'foo'), my $x;
+=over 4
 
 =item *
 
-L<base> has been upgraded from version 2.25 to 2.27.
+XXX L<message|perldiag/"message">
 
-=item *
+=back
 
-L<bignum> has been upgraded from version 0.47 to 0.49.
+=head2 Changes to Existing Diagnostics
 
-=item *
+XXX Changes (i.e. rewording) of diagnostic messages go here
 
-L<blib> has been upgraded from version 1.06 to 1.07.
+=over 4
 
 =item *
 
-L<bytes> has been upgraded from version 1.05 to 1.06.
+XXX Describe change here
 
-=item *
+=back
 
-L<Carp> has been upgraded from version 1.42 to 1.50.
+=head1 Utility Changes
 
-If a package on the call stack contains a constant named C<ISA>, Carp no
-longer throws a "Not a GLOB reference" error.
+XXX Changes to installed programs such as F<perlbug> and F<xsubpp> go here.
+Most of these are built within the directory F<utils>.
 
-L<Carp>, when generating stack traces, now attempts to work around
-longstanding bugs resulting from Perl's non-reference-counted stack.
-L<[perl #52610]|https://rt.perl.org/Ticket/Display.html?id=52610>
+[ List utility changes as a =head2 entry for each utility and =item
+entries for each change
+Use L<XXX> with program names to get proper documentation linking. ]
 
-Carp has been modified to avoid assuming that objects cannot be
-overloaded without the L<overload> module loaded (this can happen with
-objects created by XS modules).  Previously, infinite recursion would
-result if an XS-defined overload method itself called Carp.
-L<[perl #132828]|https://rt.perl.org/Ticket/Display.html?id=132828>
+=head2 L<XXX>
 
-Carp now avoids using C<overload::StrVal>, partly because older versions
-of L<overload> (included with perl 5.14 and earlier) load L<Scalar::Util>
-at run time, which will fail if Carp has been invoked after a syntax error.
+=over 4
 
 =item *
 
-L<charnames> has been upgraded from version 1.44 to 1.45.
+XXX
 
-=item *
+=back
 
-L<Compress::Raw::Zlib> has been upgraded from version 2.074 to 2.076.
+=head1 Configuration and Compilation
 
-This addresses a security vulnerability in older versions of the 'zlib' library
-(which is bundled with Compress-Raw-Zlib).
+XXX Changes to F<Configure>, F<installperl>, F<installman>, and analogous tools
+go here.  Any other changes to the Perl build process should be listed here.
+However, any platform-specific changes should be listed in the
+L</Platform Support> section, instead.
 
-=item *
+[ List changes as an =item entry ].
 
-L<Config::Extensions> has been upgraded from version 0.01 to 0.02.
+=over 4
 
 =item *
 
-L<Config::Perl::V> has been upgraded from version 0.28 to 0.29.
+XXX
 
-=item *
+=back
 
-L<CPAN> has been upgraded from version 2.18 to 2.20.
+=head1 Testing
 
-=item *
+XXX Any significant changes to the testing of a freshly built perl should be
+listed here.  Changes which create B<new> files in F<t/> go here as do any
+large changes to the testing harness (e.g. when parallel testing was added).
+Changes to existing files in F<t/> aren't worth summarizing, although the bugs
+that they represent may be covered elsewhere.
 
-L<Data::Dumper> has been upgraded from version 2.167 to 2.170.
+XXX If there were no significant test changes, say this:
 
-Quoting of glob names now obeys the Useqq option
-L<[perl #119831]|https://rt.perl.org/Ticket/Display.html?id=119831>.
+Tests were added and changed to reflect the other additions and changes
+in this release.
 
-Attempts to set an option to C<undef> through a combined getter/setter
-method are no longer mistaken for getter calls
-L<[perl #113090]|https://rt.perl.org/Ticket/Display.html?id=113090>.
+XXX If instead there were significant changes, say this:
 
-=item *
+Tests were added and changed to reflect the other additions and
+changes in this release.  Furthermore, these significant changes were
+made:
 
-L<Devel::Peek> has been upgraded from version 1.26 to 1.27.
+[ List each test improvement as an =item entry ]
 
-=item *
+=over 4
 
-L<Devel::PPPort> has been upgraded from version 3.35 to 3.40.
+=item *
 
-L<Devel::PPPort> has moved from cpan-first to perl-first maintenance
+XXX
 
-Primary responsibility for the code in Devel::PPPort has moved into core perl.
-In a practical sense there should be no change except that hopefully it will
-stay more up to date with changes made to symbols in perl, rather than needing
-to be updated after the fact.
+=back
 
-=item *
+=head1 Platform Support
 
-L<Digest::SHA> has been upgraded from version 5.96 to 6.01.
+XXX Any changes to platform support should be listed in the sections below.
 
-=item *
+[ Within the sections, list each platform as an =item entry with specific
+changes as paragraphs below it. ]
 
-L<DirHandle> has been upgraded from version 1.04 to 1.05.
+=head2 New Platforms
 
-=item *
+XXX List any platforms that this version of perl compiles on, that previous
+versions did not.  These will either be enabled by new files in the F<hints/>
+directories, or new subdirectories and F<README> files at the top level of the
+source tree.
 
-L<DynaLoader> has been upgraded from version 1.42 to 1.45.
+=over 4
 
-Its documentation now shows the use of C<__PACKAGE__> and direct object
-syntax
-L<[perl #132247]|https://rt.perl.org/Ticket/Display.html?id=132247>.
+=item XXX-some-platform
 
-=item *
+XXX
 
-L<Encode> has been upgraded from version 2.88 to 2.97.
+=back
 
-=item *
+=head2 Discontinued Platforms
 
-L<encoding> has been upgraded from version 2.19 to 2.22.
+XXX List any platforms that this version of perl no longer compiles on.
 
-=item *
+=over 4
 
-L<Errno> has been upgraded from version 1.28 to 1.29.
+=item XXX-some-platform
 
-=item *
+XXX
 
-L<experimental> has been upgraded from version 0.016 to 0.019.
+=back
 
-=item *
+=head2 Platform-Specific Notes
 
-L<Exporter> has been upgraded from version 5.72 to 5.73.
+XXX List any changes for specific platforms.  This could include configuration
+and compilation changes or changes in portability/compatibility.  However,
+changes within modules for platforms should generally be listed in the
+L</Modules and Pragmata> section.
 
-=item *
+=over 4
 
-L<ExtUtils::CBuilder> has been upgraded from version 0.280225 to 0.280230.
+=item XXX-some-platform
 
-=item *
+XXX
 
-L<ExtUtils::Constant> has been upgraded from version 0.23 to 0.25.
+=back
 
-=item *
+=head1 Internal Changes
 
-L<ExtUtils::Embed> has been upgraded from version 1.34 to 1.35.
+XXX Changes which affect the interface available to C<XS> code go here.  Other
+significant internal changes for future core maintainers should be noted as
+well.
 
-=item *
+[ List each change as an =item entry ]
 
-L<ExtUtils::Install> has been upgraded from version 2.04 to 2.14.
+=over 4
 
 =item *
 
-L<ExtUtils::MakeMaker> has been upgraded from version 7.24 to 7.34.
-
-=item *
+XXX
 
-L<ExtUtils::Miniperl> has been upgraded from version 1.06 to 1.08.
+=back
 
-=item *
+=head1 Selected Bug Fixes
 
-L<ExtUtils::ParseXS> has been upgraded from version 3.34 to 3.39.
+XXX Important bug fixes in the core language are summarized here.  Bug fixes in
+files in F<ext/> and F<lib/> are best summarized in L</Modules and Pragmata>.
 
-=item *
+[ List each fix as an =item entry ]
 
-L<ExtUtils::Typemaps> has been upgraded from version 3.34 to 3.38.
+=over 4
 
 =item *
 
-L<ExtUtils::XSSymSet> has been upgraded from version 1.3 to 1.4.
+XXX
 
-=item *
+=back
 
-L<feature> has been upgraded from version 1.47 to 1.52.
+=head1 Known Problems
 
-=item *
+XXX Descriptions of platform agnostic bugs we know we can't fix go here.  Any
+tests that had to be C<TODO>ed for the release would be noted here.  Unfixed
+platform specific bugs also go here.
+
+[ List each fix as an =item entry ]
 
-L<fields> has been upgraded from version 2.23 to 2.24.
+=over 4
 
 =item *
 
-L<File::Copy> has been upgraded from version 2.32 to 2.33.
+XXX
 
-It will now use the sub-second precision variant of utime() supplied by
-L<Time::HiRes> where available.
-L<[perl #132401]|https://rt.perl.org/Ticket/Display.html?id=132401>.
+=back
 
-=item *
+=head1 Errata From Previous Releases
 
-L<File::Fetch> has been upgraded from version 0.52 to 0.56.
+=over 4
 
 =item *
 
-L<File::Glob> has been upgraded from version 1.28 to 1.31.
-
-=item *
+XXX Add anything here that we forgot to add, or were mistaken about, in
+the perldelta of a previous release.
 
-L<File::Path> has been upgraded from version 2.12_01 to 2.15.
+=back
 
-=item *
+=head1 Obituary
 
-L<File::Spec> and L<Cwd> have been upgraded from version 3.67 to 3.74.
+XXX If any significant core contributor or member of the CPAN community has
+died, add a short obituary here.
 
-=item *
+=head1 Acknowledgements
 
-L<File::stat> has been upgraded from version 1.07 to 1.08.
-
-=item *
-
-L<FileCache> has been upgraded from version 1.09 to 1.10.
-
-=item *
-
-L<Filter::Simple> has been upgraded from version 0.93 to 0.95.
-
-=item *
-
-L<Filter::Util::Call> has been upgraded from version 1.55 to 1.58.
-
-=item *
-
-L<GDBM_File> has been upgraded from version 1.15 to 1.17.
-
-Its documentation now explains that C<each> and C<delete> don't mix in
-hashes tied to this module
-L<[perl #117449]|https://rt.perl.org/Ticket/Display.html?id=117449>.
-
-It will now retry opening with an acceptable block size if asking gdbm
-to default the block size failed
-L<[perl #119623]|https://rt.perl.org/Ticket/Display.html?id=119623>.
-
-=item *
-
-L<Getopt::Long> has been upgraded from version 2.49 to 2.5.
-
-=item *
-
-L<Hash::Util::FieldHash> has been upgraded from version 1.19 to 1.20.
-
-=item *
-
-L<I18N::Langinfo> has been upgraded from version 0.13 to 0.17.
-
-This module is now available on all platforms, emulating the system
-L<nl_langinfo(3)> on systems that lack it.  Some caveats apply, as
-L<detailed in its documentation|I18N::Langinfo>, the most severe being
-that, except for MS Windows, the C<CODESET> item is not implemented on
-those systems, always returning C<"">.
-
-It now sets the UTF-8 flag in its returned scalar if the string contains
-legal non-ASCII UTF-8, and the locale is UTF-8
-L<[perl #127288]|https://rt.perl.org/Ticket/Display.html?id=127288>.
-
-This update also fixes a bug in which the underlying locale was ignored
-for the C<RADIXCHAR> (always was returned as a dot) and the C<THOUSEP>
-(always empty).  Now the locale-appropriate values are returned.
-
-=item *
-
-L<I18N::LangTags> has been upgraded from version 0.42 to 0.43.
-
-=item *
-
-L<if> has been upgraded from version 0.0606 to 0.0608.
-
-=item *
-
-L<IO> has been upgraded from version 1.38 to 1.39.
-
-=item *
-
-L<IO::Socket::IP> has been upgraded from version 0.38 to 0.39.
-
-=item *
-
-L<IPC::Cmd> has been upgraded from version 0.96 to 1.00.
-
-=item *
-
-L<JSON::PP> has been upgraded from version 2.27400_02 to 2.97001.
-
-=item *
-
-The C<libnet> distribution has been upgraded from version 3.10 to 3.11.
-
-=item *
-
-L<List::Util> has been upgraded from version 1.46_02 to 1.49.
-
-=item *
-
-L<Locale::Codes> has been upgraded from version 3.42 to 3.56.
-
-B<NOTE>: L<Locale::Codes> scheduled to be removed from core in Perl 5.30.
-
-=item *
-
-L<Locale::Maketext> has been upgraded from version 1.28 to 1.29.
-
-=item *
-
-L<Math::BigInt> has been upgraded from version 1.999806 to 1.999811.
-
-=item *
-
-L<Math::BigInt::FastCalc> has been upgraded from version 0.5005 to 0.5006.
-
-=item *
-
-L<Math::BigRat> has been upgraded from version 0.2611 to 0.2613.
-
-=item *
-
-L<Module::CoreList> has been upgraded from version 5.20170530 to 5.20180622.
-
-=item *
-
-L<mro> has been upgraded from version 1.20 to 1.22.
-
-=item *
-
-L<Net::Ping> has been upgraded from version 2.55 to 2.62.
-
-=item *
-
-L<NEXT> has been upgraded from version 0.67 to 0.67_01.
-
-=item *
-
-L<ODBM_File> has been upgraded from version 1.14 to 1.15.
-
-=item *
-
-L<Opcode> has been upgraded from version 1.39 to 1.43.
-
-=item *
-
-L<overload> has been upgraded from version 1.28 to 1.30.
-
-=item *
-
-L<PerlIO::encoding> has been upgraded from version 0.25 to 0.26.
-
-=item *
-
-L<PerlIO::scalar> has been upgraded from version 0.26 to 0.29.
-
-=item *
-
-L<PerlIO::via> has been upgraded from version 0.16 to 0.17.
-
-=item *
-
-L<Pod::Functions> has been upgraded from version 1.11 to 1.13.
-
-=item *
-
-L<Pod::Html> has been upgraded from version 1.2202 to 1.24.
-
-A title for the HTML document will now be automatically generated by
-default from a "NAME" section in the POD document, as it used to be
-before the module was rewritten to use L<Pod::Simple::XHTML> to do the
-core of its job
-L<[perl #110520]|https://rt.perl.org/Ticket/Display.html?id=110520>.
-
-=item *
-
-L<Pod::Perldoc> has been upgraded from version 3.28 to 3.2801.
-
-=item *
-
-The C<podlators> distribution has been upgraded from version 4.09 to 4.10.
-
-Man page references and function names now follow the Linux man page
-formatting standards, instead of the Solaris standard.
-
-=item *
-
-L<POSIX> has been upgraded from version 1.76 to 1.84.
-
-Some more cautions were added about using locale-specific functions in
-threaded applications.
-
-=item *
-
-L<re> has been upgraded from version 0.34 to 0.36.
-
-=item *
-
-L<Scalar::Util> has been upgraded from version 1.46_02 to 1.50.
-
-=item *
-
-L<SelfLoader> has been upgraded from version 1.23 to 1.25.
-
-=item *
-
-L<Socket> has been upgraded from version 2.020_03 to 2.027.
-
-=item *
-
-L<sort> has been upgraded from version 2.02 to 2.04.
-
-=item *
-
-L<Storable> has been upgraded from version 2.62 to 3.08.
-
-=item *
-
-L<Sub::Util> has been upgraded from version 1.48 to 1.49.
-
-=item *
-
-L<subs> has been upgraded from version 1.02 to 1.03.
-
-=item *
-
-L<Sys::Hostname> has been upgraded from version 1.20 to 1.22.
-
-=item *
-
-L<Term::ReadLine> has been upgraded from version 1.16 to 1.17.
-
-=item *
-
-L<Test> has been upgraded from version 1.30 to 1.31.
-
-=item *
-
-L<Test::Harness> has been upgraded from version 3.38 to 3.42.
-
-=item *
-
-L<Test::Simple> has been upgraded from version 1.302073 to 1.302133.
-
-=item *
-
-L<threads> has been upgraded from version 2.15 to 2.22.
-
-The documentation now better describes the problems that arise when
-returning values from threads, and no longer warns about creating threads
-in C<BEGIN> blocks.
-L<[perl #96538]|https://rt.perl.org/Ticket/Display.html?id=96538>
-
-=item *
-
-L<threads::shared> has been upgraded from version 1.56 to 1.58.
-
-=item *
-
-L<Tie::Array> has been upgraded from version 1.06 to 1.07.
-
-=item *
-
-L<Tie::StdHandle> has been upgraded from version 4.4 to 4.5.
-
-=item *
-
-L<Time::gmtime> has been upgraded from version 1.03 to 1.04.
-
-=item *
-
-L<Time::HiRes> has been upgraded from version 1.9741 to 1.9759.
-
-=item *
-
-L<Time::localtime> has been upgraded from version 1.02 to 1.03.
-
-=item *
-
-L<Time::Piece> has been upgraded from version 1.31 to 1.3204.
-
-=item *
-
-L<Unicode::Collate> has been upgraded from version 1.19 to 1.25.
-
-=item *
-
-L<Unicode::Normalize> has been upgraded from version 1.25 to 1.26.
-
-=item *
-
-L<Unicode::UCD> has been upgraded from version 0.68 to 0.70.
-
-The function C<num> now accepts an optional parameter to help in
-diagnosing error returns.
-
-=item *
-
-L<User::grent> has been upgraded from version 1.01 to 1.02.
-
-=item *
-
-L<User::pwent> has been upgraded from version 1.00 to 1.01.
-
-=item *
-
-L<utf8> has been upgraded from version 1.19 to 1.21.
-
-=item *
-
-L<vars> has been upgraded from version 1.03 to 1.04.
-
-=item *
-
-L<version> has been upgraded from version 0.9917 to 0.9923.
-
-=item *
-
-L<VMS::DCLsym> has been upgraded from version 1.08 to 1.09.
-
-=item *
-
-L<VMS::Stdio> has been upgraded from version 2.41 to 2.44.
-
-=item *
-
-L<warnings> has been upgraded from version 1.37 to 1.42.
-
-It now includes new functions with names ending in C<_at_level>, allowing
-callers to specify the exact call frame.
-L<[perl #132468]|https://rt.perl.org/Ticket/Display.html?id=132468>
-
-=item *
-
-L<XS::Typemap> has been upgraded from version 0.15 to 0.16.
-
-=item *
-
-L<XSLoader> has been upgraded from version 0.27 to 0.30.
-
-Its documentation now shows the use of C<__PACKAGE__>, and direct object
-syntax for example C<DynaLoader> usage
-L<[perl #132247]|https://rt.perl.org/Ticket/Display.html?id=132247>.
-
-Platforms that use C<mod2fname> to edit the names of loadable
-libraries now look for bootstrap (.bs) files under the correct,
-non-edited name.
-
-=back
-
-=head2 Removed Modules and Pragmata
-
-=over 4
-
-=item *
-
-The C<VMS::stdio> compatibility shim has been removed.
-
-=back
-
-=head1 Documentation
-
-=head2 Changes to Existing Documentation
-
-We have attempted to update the documentation to reflect the changes
-listed in this document.  If you find any we have missed, send email
-to L<perl...@perl.org|mailto:perl...@perl.org>.
-
-Additionally, the following selected changes have been made:
-
-=head3 L<perlapi>
-
-=over 4
-
-=item *
-
-The API functions C<perl_parse()>, C<perl_run()>, and C<perl_destruct()>
-are now documented comprehensively, where previously the only
-documentation was a reference to the L<perlembed> tutorial.
-
-=item *
-
-The documentation of C<newGIVENOP()> has been belatedly updated to
-account for the removal of lexical C<$_>.
-
-=item *
-
-The API functions C<newCONSTSUB()> and C<newCONSTSUB_flags()> are
-documented much more comprehensively than before.
-
-=back
-
-=head3 L<perldata>
-
-=over 4
-
-=item *
-
-The section "Truth and Falsehood" in L<perlsyn> has been moved into
-L<perldata>.
-
-=back
-
-=head3 L<perldebguts>
-
-=over 4
-
-=item *
-
-The description of the conditions under which C<DB::sub()> will be called
-has been clarified.
-L<[perl #131672]|https://rt.perl.org/Ticket/Display.html?id=131672>
-
-=back
-
-=head3 L<perldiag>
-
-=over 4
-
-=item * L<perldiag/Variable length lookbehind not implemented in regex 
mE<sol>%sE<sol>>
-
-This now gives more ideas as to workarounds to the issue that was
-introduced in Perl 5.18 (but not documented explicitly in its perldelta)
-for the fact that some Unicode C</i> rules cause a few sequences such as
-
- (?<!st)
-
-to be considered variable length, and hence disallowed.
-
-=item * "Use of state $_ is experimental" in L<perldiag>
-
-This entry has been removed, as the experimental support of this construct was
-removed in perl 5.24.0.
-
-=item *
-
-The diagnostic C<Initialization of state variables in list context
-currently forbidden> has changed to C<Initialization of state variables
-in list currently forbidden>, because list-context initialization of
-single aggregate state variables is now permitted.
-
-=back
-
-=head3 L<perlembed>
-
-=over 4
-
-=item *
-
-The examples in L<perlembed> have been made more portable in the way
-they exit, and the example that gets an exit code from the embedded Perl
-interpreter now gets it from the right place.  The examples that pass
-a constructed argv to Perl now show the mandatory null C<argv[argc]>.
-
-=item *
-
-An example in L<perlembed> used the string value of C<ERRSV> as a
-format string when calling croak().  If that string contains format
-codes such as C<%s> this could crash the program.
-
-This has been changed to a call to croak_sv().
-
-An alternative could have been to supply a trivial format string:
-
-  croak("%s", SvPV_nolen(ERRSV));
-
-or as a special case for C<ERRSV> simply:
-
-  croak(NULL);
-
-=back
-
-=head3 L<perlfunc>
-
-=over 4
-
-=item *
-
-There is now a note that warnings generated by built-in functions are
-documented in L<perldiag> and L<warnings>.
-L<[perl #116080]|https://rt.perl.org/Ticket/Display.html?id=116080>
-
-=item *
-
-The documentation for the C<exists> operator no longer says that
-autovivification behaviour "may be fixed in a future release".
-We've determined that we're not going to change the default behaviour.
-L<[perl #127712]|https://rt.perl.org/Ticket/Display.html?id=127712>
-
-=item *
-
-A couple of small details in the documentation for the C<bless> operator
-have been clarified.
-L<[perl #124428]|https://rt.perl.org/Ticket/Display.html?id=124428>
-
-=item *
-
-The description of C<@INC> hooks in the documentation for C<require>
-has been corrected to say that filter subroutines receive a useless
-first argument.
-L<[perl #115754]|https://rt.perl.org/Ticket/Display.html?id=115754>
-
-=item *
-
-The documentation of C<ref> has been rewritten for clarity.
-
-=item *
-
-The documentation of C<use> now explains what syntactically qualifies
-as a version number for its module version checking feature.
-
-=item *
-
-The documentation of C<warn> has been updated to reflect that since Perl
-5.14 it has treated complex exception objects in a manner equivalent
-to C<die>.
-L<[perl #121372]|https://rt.perl.org/Ticket/Display.html?id=121372>
-
-=item *
-
-The documentation of C<die> and C<warn> has been revised for clarity.
-
-=item *
-
-The documentation of C<each> has been improved, with a slightly more
-explicit description of the sharing of iterator state, and with
-caveats regarding the fragility of while-each loops.
-L<[perl #132644]|https://rt.perl.org/Ticket/Display.html?id=132644>
-
-=item *
-
-Clarification to C<require> was added to explain the differences between
-
-    require Foo::Bar;
-    require "Foo/Bar.pm";
-
-=back
-
-=head3 L<perlgit>
-
-=over 4
-
-=item *
-
-The precise rules for identifying C<smoke-me> branches are now stated.
-
-=back
-
-=head3 L<perlguts>
-
-=over 4
-
-=item *
-
-The section on reference counting in L<perlguts> has been heavily revised,
-to describe references in the way a programmer needs to think about them
-rather than in terms of the physical data structures.
-
-=item *
-
-Improve documentation related to UTF-8 multibytes.
-
-=back
-
-=head3 L<perlintern>
-
-=over 4
-
-=item *
-
-The internal functions C<newXS_len_flags()> and C<newATTRSUB_x()> are
-now documented.
-
-=back
-
-=head3 L<perlobj>
-
-=over 4
-
-=item *
-
-The documentation about C<DESTROY> methods has been corrected, updated,
-and revised, especially in regard to how they interact with exceptions.
-L<[perl #122753]|https://rt.perl.org/Ticket/Display.html?id=122753>
-
-=back
-
-=head3 L<perlop>
-
-=over 4
-
-=item *
-
-The description of the C<x> operator in L<perlop> has been clarified.
-L<[perl #132460]|https://rt.perl.org/Ticket/Display.html?id=132460>
-
-=item *
-
-L<perlop> has been updated to note that C<qw>'s whitespace rules differ
-from that of C<split>'s in that only ASCII whitespace is used.
-
-=item *
-
-The general explanation of operator precedence and associativity has
-been corrected and clarified.
-L<[perl #127391]|https://rt.perl.org/Ticket/Display.html?id=127391>
-
-=item *
-
-The documentation for the C<\> referencing operator now explains the
-unusual context that it supplies to its operand.
-L<[perl #131061]|https://rt.perl.org/Ticket/Display.html?id=131061>
-
-=back
-
-=head3 L<perlrequick>
-
-=over 4
-
-=item *
-
-Clarifications on metacharacters and character classes
-
-=back
-
-=head3 L<perlretut>
-
-=over 4
-
-=item *
-
-Clarify metacharacters.
-
-=back
-
-=head3 L<perlrun>
-
-=over 4
-
-=item *
-
-Clarify the differences between B<< -M >> and B<< -m >>.
-L<[perl #131518]|https://rt.perl.org/Ticket/Display.html?id=131518>
-
-=back
-
-=head3 L<perlsec>
-
-=over 4
-
-=item *
-
-The documentation about set-id scripts has been updated and revised.
-L<[perl #74142]|https://rt.perl.org/Ticket/Display.html?id=74142>
-
-=item *
-
-A section about using C<sudo> to run Perl scripts has been added.
-
-=back
-
-=head3 L<perlsyn>
-
-=over 4
-
-=item *
-
-The section "Truth and Falsehood" in L<perlsyn> has been removed from
-that document, where it didn't belong, and merged into the existing
-paragraph on the same topic in L<perldata>.
-
-=item *
-
-The means to disambiguate between code blocks and hash constructors,
-already documented in L<perlref>, are now documented in L<perlsyn> too.
-L<[perl #130958]|https://rt.perl.org/Ticket/Display.html?id=130958>
-
-=back
-
-=head3 L<perluniprops>
-
-=over 4
-
-=item *
-
-L<perluniprops> has been updated to note that C<\p{Word}> now includes
-code points matching the C<\p{Join_Control}> property.  The change to
-the property was made in Perl 5.18, but not documented until now.  There
-are currently only two code points that match this property U+200C (ZERO
-WIDTH NON-JOINER) and U+200D (ZERO WIDTH JOINER).
-
-=item *
-
-For each binary table or property, the documentation now includes which
-characters in the range C<\x00-\xFF> it matches, as well as a list of
-the first few ranges of code points matched above that.
-
-=back
-
-=head3 L<perlvar>
-
-=over 4
-
-=item *
-
-The entry for C<$+> in perlvar has been expanded upon to describe handling of
-multiply-named capturing groups.
-
-=back
-
-=head3 L<perlfunc>, L<perlop>, L<perlsyn>
-
-=over 4
-
-=item *
-
-In various places, improve the documentation of the special cases
-in the condition expression of a while loop, such as implicit C<defined>
-and assignment to C<$_>.
-L<[perl #132644]|https://rt.perl.org/Ticket/Display.html?id=132644>
-
-=back
-
-=head1 Diagnostics
-
-The following additions or changes have been made to diagnostic output,
-including warnings and fatal error messages.  For the complete list of
-diagnostic messages, see L<perldiag>.
-
-=head2 New Diagnostics
-
-=head3 New Errors
-
-=over 4
-
-=item *
-
-L<Can't "goto" into a "given" block|perldiag/"Can't E<quot>gotoE<quot> into a 
E<quot>givenE<quot> block">
-
-(F) A "goto" statement was executed to jump into the middle of a C<given>
-block.  You can't get there from here.  See L<perlfunc/goto>.
-
-=item *
-
-L<Can't "goto" into a binary or list expression|perldiag/"Can't 
E<quot>gotoE<quot> into a binary or list expression">
-
-Use of C<goto> to jump into the parameter of a binary or list operator has
-been prohibited, to prevent crashes and stack corruption.
-L<[perl #130936]|https://rt.perl.org/Ticket/Display.html?id=130936>
-
-You may only enter the I<first> argument of an operator that takes a fixed
-number of arguments, since this is a case that will not cause stack
-corruption.
-L<[perl #132854]|https://rt.perl.org/Ticket/Display.html?id=132854>
-
-=back
-
-=head3 New Warnings
-
-=over 4
-
-=item *
-
-L<Old package separator used in string|perldiag/"Old package separator used in 
string">
-
-(W syntax) You used the old package separator, "'", in a variable
-named inside a double-quoted string; e.g., C<"In $name's house">.  This
-is equivalent to C<"In $name::s house">.  If you meant the former, put
-a backslash before the apostrophe (C<"In $name\'s house">).
-
-=item *
-
-L<perldiag/Locale '%s' contains (at least) the following characters which
-have unexpected meanings: %s  The Perl program will use the expected
-meanings>
-
-=back
-
-=head2 Changes to Existing Diagnostics
-
-=over 4
-
-=item *
-
-A false-positive warning that was issued when using a
-numerically-quantified sub-pattern in a recursive regex has been
-silenced. L<[perl 
#131868]|https://rt.perl.org/Public/Bug/Display.html?id=131868>
-
-=item *
-
-The warning about useless use of a concatenation operator in void context
-is now generated for expressions with multiple concatenations, such as
-C<$a.$b.$c>, which used to mistakenly not warn.
-L<[perl #6997]|https://rt.perl.org/Ticket/Display.html?id=6997>
-
-=item *
-
-Warnings that a variable or subroutine "masks earlier declaration in same
-...", or that an C<our> variable has been redeclared, have been moved to a
-new warnings category "shadow".  Previously they were in category "misc".
-
-=item *
-
-The deprecation warning from C<Sys::Hostname::hostname()> saying that
-it doesn't accept arguments now states the Perl version in which the
-warning will be upgraded to an error.
-L<[perl #124349]|https://rt.perl.org/Ticket/Display.html?id=124349>
-
-=item *
-
-The L<perldiag> entry for the error regarding a set-id script has been
-expanded to make clear that the error is reporting a specific security
-vulnerability, and to advise how to fix it.
-
-=item *
-
-The C<< Unable to flush stdout >> error message was missing a trailing
-newline. [debian #875361]
-
-=back
-
-=head1 Utility Changes
-
-=head2 L<perlbug>
-
-=over 4
-
-=item *
-
-C<--help> and C<--version> options have been added.
-
-=back
-
-=head1 Configuration and Compilation
-
-=over 4
-
-=item * C89 requirement
-
-Perl has been documented as requiring a C89 compiler to build since October
-1998.  A variety of simplifications have now been made to Perl's internals to
-rely on the features specified by the C89 standard. We believe that this
-internal change hasn't altered the set of platforms that Perl builds on, but
-please report a bug if Perl now has new problems building on your platform.
-
-=item *
-
-On GCC, C<-Werror=pointer-arith> is now enabled by default,
-disallowing arithmetic on void and function pointers.
-
-=item *
-
-Where an HTML version of the documentation is installed, the HTML
-documents now use relative links to refer to each other.  Links from
-the index page of L<perlipc> to the individual section documents are
-now correct.
-L<[perl #110056]|https://rt.perl.org/Ticket/Display.html?id=110056>
-
-=item *
-
-F<lib/unicore/mktables> now correctly canonicalizes the names of the
-dependencies stored in the files it generates.
-
-F<regen/mk_invlists.pl>, unlike the other F<regen/*.pl> scripts, used
-C<$0> to name itself in the dependencies stored in the files it
-generates.  It now uses a literal so that the path stored in the
-generated files doesn't depend on how F<regen/mk_invlists.pl> is
-invoked.
-
-This lack of canonical names could cause test failures in F<t/porting/regen.t>.
-L<[perl #132925]|https://rt.perl.org/Ticket/Display.html?id=132925>
-
-=item * New probes
-
-=over 2
-
-=item HAS_BUILTIN_ADD_OVERFLOW
-
-=item HAS_BUILTIN_MUL_OVERFLOW
-
-=item HAS_BUILTIN_SUB_OVERFLOW
-
-=item HAS_THREAD_SAFE_NL_LANGINFO_L
-
-=item HAS_LOCALECONV_L
-
-=item HAS_MBRLEN
-
-=item HAS_MBRTOWC
-
-=item HAS_MEMRCHR
-
-=item HAS_NANOSLEEP
-
-=item HAS_STRNLEN
... 828 lines suppressed ...

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