PERL5360DELTA(1)

💖 NAME 💖

perl5360delta — what is new for perl v5.36.0. Also, bestie, this is the Perl Programmers Reference Guide page, so you're in the right place.

🌸 DESCRIPTION 🌸

This document describes differences between the 5.34.0 release and the 5.36.0 release.

✨ Core Enhancements ✨

💅 `"use v5.36"`

As always, "use v5.36" turns on the feature bundle for that version of Perl.

The 5.36 bundle enables the "signatures" feature. Introduced in Perl version 5.20.0, and modified several times since, the subroutine signatures feature is now no longer considered experimental. It is now considered a stable language feature and no longer prints a warning.

use v5.36;

sub add ($x, $y) {
  return $x + $y;
}

Despite this, certain elements of signatured subroutines remain experimental; see below.

The 5.36 bundle enables the "isa" feature. Introduced in Perl version 5.32.0, this operator has remained unchanged since then. The operator is now considered a stable language feature. For more detail see "Class Instance Operator" in perlop.

The 5.36 bundle also disables the features "indirect", and "multidimensional". These will forbid, respectively: the use of "indirect" method calls (like $x = new Class;); the use of a list expression as a hash key to simulate sparse multidimensional arrays. The specifics of these changes can be found in feature, but the short version is: this is a bit like having more "use strict" turned on, disabling features that cause more trouble than they're worth.

Furthermore, "use v5.36" will also enable warnings as if you'd written "use warnings".

Finally, with this release, the experimental "switch" feature, present in every feature bundle since they were introduced in v5.10, has been removed from the v5.36 bundle. If you want to use it (against our advice), you'll have to enable it explicitly.

🎀 -g command-line flag

A new command-line flag, -g, is available. It is a simpler alias for -0777.

For more information, see "-g" in perlrun.

🌈 Unicode 14.0 is supported

See https://www.unicode.org/versions/Unicode14.0.0/ for details.

🦋 regex sets are no longer considered experimental

Prior to this release, the regex sets feature (officially named "Extended Bracketed Character Classes") was considered experimental. Introduced in Perl version 5.18.0, and modified several times since, this is now considered a stable language feature and its use no longer prints a warning. See "Extended Bracketed Character Classes" in perlrecharclass.

🧚 Variable length lookbehind is mostly no longer considered experimental

Prior to this release, any form of variable length lookbehind was considered experimental. With this release the experimental status has been reduced to cover only lookbehind that contains capturing parenthesis. This is because it is not clear if

"aaz"=~/(?=z)(?<=(a|aa))/

should match and leave $1 equaling "a" or "aa". Currently it will match the longest possible alternative, "aa". While we are confident that the overall construct will now match only when it should, we are not confident that we will keep the current "longest match" behavior.

🔥 SIGFPE no longer deferred

Floating-point exceptions are now delivered immediately, in the same way as other "fault"-like signals such as SIGSEGV. This means one has at least a chance to catch such a signal with a $SIG{FPE} handler, e.g. so that "die" can report the line in perl that triggered it.

👑 Stable boolean tracking

The "true" and "false" boolean values, often accessed by constructions like "!!0" and "!!1", as well as being returned from many core functions and operators, now remember their boolean nature even through assignment into variables. The new function is_bool() in builtin can check whether a value has boolean nature.

This is likely to be useful when interoperating with other languages or data-type serialisation, among other places.

💜 iterating over multiple values at a time (experimental)

You can now iterate over multiple values at a time by specifying a list of lexicals within parentheses. For example,

for my ($key, $value) (%hash) { ... }
for my ($left, $right, $gripping) (@moties) { ... }

Prior to perl v5.36, attempting to specify a list after "for my" was a syntax error.

This feature is currently experimental and will cause a warning of category "experimental::for_list". For more detail see "Compound Statements" in perlsyn. See also "builtin::indexed" in this document, which is a handy companion to n-at-a-time foreach.

💖 builtin functions (experimental)

A new core module builtin has been added, which provides documentation for new always-present functions that are built into the interpreter.

say "Reference type of arrays is ", builtin::reftype([]);

It also provides a lexical import mechanism for providing short name versions of these functions.

use builtin 'reftype';
say "Reference type of arrays is ", reftype([]);

This builtin function mechanism and the functions it provides are all currently experimental. We expect that "builtin" itself will cease to be experimental in the near future, but that individual functions in it may become stable on an ongoing basis. Other functions will be added to "builtin" over time.

For details, see builtin, but here's a summary of builtin functions in v5.36:

🌸 builtin::trim

This function treats its argument as a string, returning the result of removing all white space at its beginning and ending.

🌟 builtin::indexed

This function returns a list twice as big as its argument list, where each item is preceded by its index within that list. This is primarily useful for using the new "foreach" syntax with multiple iterator variables to iterate over an array or list, while also tracking the index of each item:

use builtin 'indexed';

foreach my ($index, $val) (indexed @array) {
    ...
}

💫 builtin::true, builtin::false, builtin::is_bool

"true" and "false" return boolean true and false values. Perl is still perl, and doesn't have strict typing of booleans, but these values will be known to have been created as booleans. "is_bool" will tell you whether a value was known to have been created as a boolean.

🫶 builtin::weaken, builtin::unweaken, builtin::is_weak

These functions will, respectively: weaken a reference; strengthen a reference; and return whether a reference is weak. (A weak reference is not counted for garbage collection purposes. See perlref.) These can take the place of some similar routines in Scalar::Util.

🎀 builtin::blessed, builtin::refaddr, builtin::reftype

These functions provide more data about references (or non-references, actually!) and can take the place of similar routines found in Scalar::Util.

✨ builtin::ceil, builtin::floor

"ceil" returns the smallest integer greater than or equal to its argument. "floor" returns the largest integer less than or equal to its argument. These can take the place of similar routines found in POSIX.

🦋 `"defer"` blocks (experimental)

This release adds support for "defer" blocks, which are blocks of code prefixed by the "defer" modifier. They provide a section of code which runs at a later time, during scope exit.

In brief, when a "defer" block is reached at runtime, its body is set aside to be run when the enclosing scope is exited. It is unlike a UNITCHECK (among other reasons) in that if the block containing the "defer" block is exited before the block is reached, it will not be run.

"defer" blocks can be used to take the place of "scope guard" objects where an object is passed a code block to be run by its destructor.

For more information, see "defer blocks" in perlsyn.

🌈 try/catch can now have a `"finally"` block (experimental)

The experimental "try"/"catch" syntax has been extended to support an optional third block introduced by the "finally" keyword.

try {
    attempt();
    print "Success\n";
}
catch ($e) {
    print "Failure\n";
}
finally {
    print "This happens regardless\n";
}

This provides code which runs at the end of the "try"/"catch" construct, even if aborted by an exception or control-flow keyword. They are similar to "defer" blocks.

For more information, see "Try Catch Exception Handling" in perlsyn.

🧚 non-ASCII delimiters for quote-like operators (experimental)

Perl traditionally has allowed just four pairs of string/pattern delimiters: "( )" "{ }" "[ ]" and "< >", all in the ASCII range. Unicode has hundreds more possibilities, and using this feature enables many of them. When enabled, you can say "qr« »" for example, or "use utf8; q𝄃string𝄂". See "The 'extra_paired_delimiters' feature" in feature for details.

💀 @_ is now experimental within signatured subs

Even though subroutine signatures are now stable, use of the legacy arguments array (@_) with a subroutine that has a signature remains experimental, with its own warning category. Silencing the "experimental::signatures" warning category is not sufficient to dismiss this. The new warning is emitted with the category name "experimental::args_array_with_signatures".

Any subroutine that has a signature and tries to make use of the defaults argument array or an element thereof (@_ or $_[INDEX]), either explicitly or implicitly (such as "shift" or "pop" with no argument) will provoke a warning at compile-time:

use v5.36;

sub f ($x, $y = 123) {
  say "The first argument is $_[0]";
}

Use of @_ in array element with signatured subroutine is experimental
at file.pl line 4.

The behaviour of code which attempts to do this is no longer specified, and may be subject to change in a future version.

💥 Incompatible Changes 💥

🚨 A physically empty sort is now a compile-time error

@a = sort @empty; # unaffected
@a = sort;        # now a compile-time error
@a = sort ();     # also a compile-time error

A bare sort used to be a weird way to create an empty list; now it croaks at compile time. This change is intended to free up some of the syntax space for possible future enhancements to "sort".

💅 DEPRECATIONS 💅

😭 `"use VERSION"` (where VERSION is below v5.11) after `"use v5.11"` is deprecated 😭

Okay bestie, listen up. When you're in the scope of use v5.11 or later, and then you hit a use vX line where X is lower than v5.11? It's gonna warn you now. Like:

Downgrading a use VERSION declaration to below v5.11 is deprecated

For example:

use v5.14;
say "The say statement is permitted";
use v5.8;                               # This will print a warning
print "We must use print\n";

Why tho? Because the Perl team is literally planning to change how this works. Since Perl v5.12 (and some bits of v5.11), strict is enabled unless it was previously disabled. In other words:

no strict;
use v5.12;  # will not enable strict, because "no strict" preceded it
$x = 1;     # permitted, despite no "my" declaration

In the future, this behavior will be eliminated and use VERSION will always enable strict for versions v5.12 and later. Periodt.

So if you're out here mixing versions like that, you should use lexical scoping with block syntax to keep those differently versioned regions lexically isolated. Like this:

{
    use v5.14;
    say "The say statement is permitted";
}

{
    use v5.8;                           # No warning is emitted
    print "We must use print\n";
}

And honestly? This is probably not something you ever need to do! If the first block compiles, it means you're using perl v5.14.0 or later. So slay, but also chill.

⚡ PERFORMANCE ENHANCEMENTS ⚡

We now probe for compiler support for C11 thread local storage, and where available use this for "implicit context" for XS extensions making API calls for a threaded Perl build. This requires fewer function calls at the C level than POSIX thread specific storage. We continue to use the pthreads approach if the C11 approach is not available.

Configure run with the defaults will build an unthreaded Perl (which is slightly faster), but most operating systems ship a threaded Perl.

Perl can now be configured to no longer allocate keys for large hashes from the shared string table.

The same internal datatype (PVHV) is used for all of

Symbol tables
Objects (by default)
Associative arrays

The shared string table was originally added to improve performance for blessed hashes used as objects, because every object instance has the same keys, so it is an optimisation to share memory between them. It also makes sense for symbol tables, where derived classes will have the same keys (typically method names), and the OP trees built for method calls can also share memory. The shared string table behaves roughly like a cache for hash keys.

But for hashes actually used as associative arrays — mapping keys to values — typically the keys are not re-used in other hashes. For example, "seen" hashes are keyed by object IDs (or addresses), and logically these keys won't repeat in other hashes.

Storing these "used just once" keys in the shared string table increases CPU and RAM use for no gain. For such keys the shared string table behaves as a cache with a 0% hit rate. Storing all the keys there increases the total size of the shared string table, as well as increasing the number of times it is resized as it grows. Worse — in any environment that has "copy on write" memory for child process (such as a pre-forking server), the memory pages used for the shared string table rapidly need to be copied as the child process manipulates hashes. Hence if most of the shared string table is such that keys are used only in one place, there is no benefit from re-use within the perl interpreter, but a high cost due to more pages for the OS to copy.

The perl interpreter can now be Configured to disable shared hash keys for "large" hashes (that are neither objects nor symbol tables). To do so, add -Accflags='-DPERL_USE_UNSHARED_KEYS_IN_LARGE_HASHES' to your Configure options. "Large" is a heuristic — currently the heuristic is that sharing is disabled when adding a key to a hash triggers allocation of more storage, and the hash has more than 42 keys.

This might cause slightly increased memory usage for programs that create (unblessed) data structures that contain multiple large hashes that share the same keys. But generally our testing suggests that for the specific cases described it is a win, and other code is unaffected.

In certain scenarios, creation of new scalars is now noticeably faster.

For example, the following code is now executing ~30% faster:

$str = "A" x 64;
for (0..1_000_000) {
    @svs = split //, $str
}

(You can read more about this one in [perl #19414] <https://github.com/Perl/perl5/pull/19414>.)

✨ okay that's the tea for this part, more coming bestie ✨

🌈 Modules and Pragmata 🌈

Okay bestie, this is the part where literally everything in the toolbox got a glow-up. Strap in, it's a long one, but every single one of these slays in its own way. 💅

✨ Updated Modules and Pragmata ✨

Archive::Tar — upgraded from version 2.38 to 2.40 🎀
Attribute::Handlers — upgraded from version 1.01 to 1.02
attributes — upgraded from version 0.33 to 0.34
B — upgraded from version 1.82 to 1.83
B::Concise — upgraded from version 1.004 to 1.006
B::Deparse — upgraded from version 1.56 to 1.64
bignum — upgraded from version 0.51 to 0.65
charnames — upgraded from version 1.48 to 1.50
Compress::Raw::Bzip2 — upgraded from version 2.101 to 2.103
Compress::Raw::Zlib — upgraded from version 2.101 to 2.105
CPAN — upgraded from version 2.28 to 2.33
Data::Dumper — upgraded from version 2.179 to 2.184
DB_File — upgraded from version 1.855 to 1.857
Devel::Peek — upgraded from version 1.30 to 1.32
Devel::PPPort — upgraded from version 3.62 to 3.68
diagnostics — upgraded from version 1.37 to 1.39
Digest — upgraded from version 1.19 to 1.20
DynaLoader — upgraded from version 1.50 to 1.52
Encode — upgraded from version 3.08 to 3.17
Errno — upgraded from version 1.33 to 1.36
experimental — upgraded from version 0.024 to 0.028
Exporter — upgraded from version 5.76 to 5.77
ExtUtils::MakeMaker — upgraded from version 7.62 to 7.64
ExtUtils::Miniperl — upgraded from version 1.10 to 1.11
ExtUtils::ParseXS — upgraded from version 3.43 to 3.45
ExtUtils::Typemaps — upgraded from version 3.43 to 3.45
Fcntl — upgraded from version 1.14 to 1.15
feature — upgraded from version 1.64 to 1.72
File::Compare — upgraded from version 1.1006 to 1.1007
File::Copy — upgraded from version 2.35 to 2.39
File::Fetch — upgraded from version 1.00 to 1.04
File::Find — upgraded from version 1.39 to 1.40
File::Glob — upgraded from version 1.33 to 1.37
File::Spec — upgraded from version 3.80 to 3.84
File::stat — upgraded from version 1.09 to 1.12
FindBin — upgraded from version 1.52 to 1.53
GDBM_File — upgraded from version 1.19 to 1.23
Hash::Util — upgraded from version 0.25 to 0.28
Hash::Util::FieldHash — upgraded from version 1.21 to 1.26
HTTP::Tiny — upgraded from version 0.076 to 0.080
I18N::Langinfo — upgraded from version 0.19 to 0.21
if — upgraded from version 0.0609 to 0.0610
IO — upgraded from version 1.46 to 1.50
IO-Compress — upgraded from version 2.102 to 2.106
IPC::Open3 — upgraded from version 1.21 to 1.22
JSON::PP — upgraded from version 4.06 to 4.07
libnet — upgraded from version 3.13 to 3.14
Locale::Maketext — upgraded from version 1.29 to 1.31
Math::BigInt — upgraded from version 1.999818 to 1.999830
Math::BigInt::FastCalc — upgraded from version 0.5009 to 0.5012
Math::BigRat — upgraded from version 0.2614 to 0.2621
Module::CoreList — upgraded from version 5.20210520 to 5.20220520
mro — upgraded from version 1.25_001 to 1.26 (yes the underscore version was real, don't @ me)
NEXT — upgraded from version 0.68 to 0.69
Opcode — upgraded from version 1.50 to 1.57
open — upgraded from version 1.12 to 1.13
overload — upgraded from version 1.33 to 1.35
perlfaq — upgraded from version 5.20210411 to 5.20210520
PerlIO — upgraded from version 1.11 to 1.12
Pod::Functions — upgraded from version 1.13 to 1.14
Pod::Html — upgraded from version 1.27 to 1.33
Pod::Simple — upgraded from version 3.42 to 3.43
POSIX — upgraded from version 1.97 to 2.03 🔥
re — upgraded from version 0.41 to 0.43
Scalar::Util — upgraded from version 1.55 to 1.62
sigtrap — upgraded from version 1.09 to 1.10
Socket — upgraded from version 2.031 to 2.033
sort — upgraded from version 2.04 to 2.05
Storable — upgraded from version 3.23 to 3.26
Sys::Hostname — upgraded from version 1.23 to 1.24
Test::Harness — upgraded from version 3.43 to 3.44
Test::Simple — upgraded from version 1.302183 to 1.302190
Text::ParseWords — upgraded from version 3.30 to 3.31
Text::Tabs — upgraded from version 2013.0523 to 2021.0814
Text::Wrap — upgraded from version 2013.0523 to 2021.0814
threads — upgraded from version 2.26 to 2.27
threads::shared — upgraded from version 1.62 to 1.64
Tie::Handle — upgraded from version 4.2 to 4.3
Tie::Hash — upgraded from version 1.05 to 1.06
Tie::Scalar — upgraded from version 1.05 to 1.06
Tie::SubstrHash — upgraded from version 1.00 to 1.01
Time::HiRes — upgraded from version 1.9767 to 1.9770
Unicode::Collate — upgraded from version 1.29 to 1.31
Unicode::Normalize — upgraded from version 1.28 to 1.31
Unicode::UCD — upgraded from version 0.75 to 0.78
UNIVERSAL — upgraded from version 1.13 to 1.14
version — upgraded from version 0.9928 to 0.9929
VMS::Filespec — upgraded from version 1.12 to 1.13
VMS::Stdio — upgraded from version 2.45 to 2.46
warnings — upgraded from version 1.51 to 1.58
Win32 — upgraded from version 0.57 to 0.59
XS::APItest — upgraded from version 1.16 to 1.22
XS::Typemap — upgraded from version 0.18 to 0.19
XSLoader — upgraded from version 0.30 to 0.31

📚 Documentation 📚

🆕 New Documentation

Porting/vote_admin_guide.pod

This document provides the process for administering an election or vote within the Perl Core Team. 🗳️ Like, democracy but make it Perl.

💫 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, open an issue at <https://github.com/Perl/perl5/issues>. (bestie if you spot a typo pls pls pls file it, we're begging 🥺)

Additionally, the following selected changes have been made:

`perlapi`

This has been cleaned up some, and more than 80% of the (previously many) undocumented functions have now either been documented or deemed to have been inappropriately marked as API.

As always, Patches Welcome! 🫶

`perldeprecation`

notes the new location for functions moved from Pod::Html to Pod::Html::Util that are no longer intended to be used outside of core. iykyk.

`perlexperiment`

notes the ":win32" IO pseudolayer is removed (this happened in 5.35.2). rip bozo 💀

`perlgov`

The election process has been finetuned to allow the vote to be skipped if there are no more candidates than open seats. (no contestants? no contest. iconic ✨)
A special election is now allowed to be postponed for up to twelve weeks, for example until a normal election.

`perlop`

now notes that an invocant only needs to be an object or class name for method calls, not for subroutine references.

`perlre`

Updated to discourage the use of the /d regexp modifier. 🚫 (it's giving deprecated, lowkey)

`perlrun`

-? is now a synonym for -h
-g is now a synonym for -0777

🔍 Diagnostics 🔍

So bestie, here's the tea on all the new error messages, warnings, and glow-ups to the ones we already had. For the complete list of diagnostic messages, go peek at perldiag. 📖

💅 New Diagnostics 💅

💀 New Errors 💀

Can't "%s" out of a "defer" block — this one's a big fat (F) (fatal). Somebody tried to yeet themselves out of a defer block's scope with a control-flow statement like return, goto, or a loop control. Nope, not permitted, absolutely not, the audacity. 🙅‍♀️
Can't modify %s in %s (for scalar assignment to "undef") — okay so if you try to do a scalar assignment to undef, like with undef = $foo;, that used to blow up at runtime with a fatal error saying Modification of a read-only value attempted. But like, catching it earlier is way more helpful, so now it's a compile time error, and the message you get is Can't modify undef operator in scalar assignment. Glow-up moment. ✨
panic: newFORLOOP, %s — the parser failed an internal consistency check while trying to parse a foreach loop. That's a genuine 💀 panic, not a vibe.

🌸 New Warnings 🌸

Built-in function '%s' is experimental — you're calling something in the builtin:: namespace, and that whole thing is currently experimental. Lowkey iconic, highkey risky. 🧪
defer is experimental — the defer block modifier is experimental, bestie. If you really wanna use it, you can silence the warning with no warnings 'experimental::defer', but know that in doing so you are taking the risk that your code may break in a future Perl version. That's the deal, take it or leave it. 🫶
Downgrading a use VERSION declaration to below v5.11 is deprecated — this warning shows up on a use VERSION statement that requests a version below v5.11 (that's the zone where the effects of use strict would get disabled), and only after you'd previously declared one with a larger number (which would have enabled those effects). Downgrade behavior, honestly. 📉
for my (...) is experimental — you used for to iterate multiple values at a time. This syntax is currently experimental and its behaviour may change in future releases of Perl. Cute but unstable. 🎀
Implicit use of @_ in %s with signatured subroutine is experimental — an expression that implicitly involves the @_ arguments array got found in a subroutine that uses a signature. Rude of it, honestly.
Use of @_ in %s with signatured subroutine is experimental — same energy, but this time the expression involving the @_ arguments array was found in a subroutine that uses a signature. 🫣
Wide character in $0 — trying to shove wide characters into the program name ($0) now provokes this warning. Respect the name field's boundaries, bestie. 🌈

🦋 Changes to Existing Diagnostics 🦋

'/' does not take a repeat count in %s — this warning used to not include the in %s part. Now it does. Inclusive queen. 👑
Subroutine %s redefined — localized subroutine redefinitions no longer trigger this warning. Peace and quiet, finally. 😌
unexpected constant lvalue entersub entry via type/targ %d:%d now has a panic prefix — this makes it consistent with the other internal-consistency checks that happen when compiling a subroutine. Consistency is the moment. ✨
Useless use of sort in scalar context is now chillin' in the brand new scalar category. Here's the lore: when sort is used in scalar context, it provokes a warning that doing this is not useful. That warning used to live in the void category. A whole new category for warnings about scalar context has been added now, called scalar. New home, same chaos. 🏡
Removed a number of diagnostics — so many diagnostics that got removed from the perl core across many years have now also been removed from the documentation. Spring cleaning fr fr. 🧹

⚙️ Configuration and Compilation ⚙️

The Perl C source code now uses some C99 features, which we have verified are supported by all compilers we target. This means that Perl's headers now contain some code that is legal in C99 but not C89.

This may cause problems for some XS modules that unconditionally add -Werror=declaration-after-statement to their C compiler flags if compiling with gcc or clang. Earlier versions of Perl support long obsolete compilers that are strict in rejecting certain C99 features, particularly mixed declarations and code, and hence it makes sense for XS module authors to audit that their code does not violate this. However, doing this is now only possible on these earlier versions of Perl, hence these modules need to be changed to only add this flag for $] < 5.035005. 😭

The makedepend step is now run in parallel by using make. When using MAKEFLAGS=-j8, this significantly reduces the time required for:

sh ./makedepend MAKE=make cflags

Speed, we love to see it. 🏎️💨

Configure now tests whether #include <xlocale.h> is required to use the POSIX 1003 thread-safe locale functions or some related extensions. This prevents problems where a non-public xlocale.h is removed in a library update, or xlocale.h isn't intended for public use. (github #18936 <https://github.com/Perl/perl5/pull/18936>) 🔧

🧪 Testing 🧪

Tests were added and changed to reflect the other additions and changes in this release. Gotta keep the receipts accurate, y'know? ✅

🖥️ Platform Support 🖥️

🪟 Windows 🪟

Support for old MSVC++ (pre-VC12) has been removed. These did not support C99 and hence can no longer be used to compile perl. Sorry to that compiler but it had to go. 💀
Support for compiling perl on Windows using Microsoft Visual Studio 2022 (containing Visual C++ 14.3) has been added. New era unlocked. 🎉
The :win32 IO layer has been removed. This experimental replacement for the :unix layer never reached maturity in its nearly two decades of existence. It's giving "tried for 20 years, still not ready," and we respect the attempt but it's over. 🕊️

🦋 VMS 🦋

keys %ENV on VMS returns consistent results

On VMS, entries in the %ENV hash are loaded from the OS environment on first access, hence the first iteration of %ENV requires the entire environment to be scanned to find all possible keys. This initialisation had always been done correctly for full iteration, but previously was not happening for %ENV in scalar context, meaning that scalar %ENV would return 0 if called before any other %ENV access, or would only return the count of keys accessed if there had been no iteration. 😵‍💫

These bugs are now fixed — %ENV and keys %ENV in scalar context now return the correct result — the count of all keys in the environment. Slay. 🫶

🪦 Discontinued Platforms 🪦

AT&T UWIN

UWIN is a UNIX compatibility layer for Windows. It was last released in 2012 and has been superseded by Cygwin these days. Rip bozo, Cygwin ate. 🍽️

DOS/DJGPP

DJGPP is a port of the GNU toolchain to 32-bit x86 systems running DOS. The last known attempt to build Perl on it was on 5.20, which only got as far as building miniperl. So close and yet so far, bestie. 😭

NetWare

Support code for Novell NetWare has been removed. NetWare was a server operating system by Novell. The port was last updated in July 2002, and the platform itself in May 2009.

And here's the wild part: unrelated changes accidentally broke the build for the NetWare port in September 2009, and in 12 years no-one has reported this. Twelve. Years. Not one person noticed. 💀💀💀

📝 Platform-Specific Notes 📝

z/OS

This update enables us to build EBCDIC static/dynamic and 31-bit/64-bit addressing mode Perl. The number of tests that pass is consistent with the baseline before these updates. 📊

These changes also provide the base support to be able to provide ASCII static/dynamic and 31-bit/64-bit addressing mode Perl. 🌈

The z/OS (previously called OS/390) README was updated to describe ASCII and EBCDIC builds. Documentation glow-up, we love to see it. ✨

🔧 Internal Changes 🔧

Okay bestie, gather round, because the internals got a whole glow-up. ✨

Since PERL_OBJECT got removed back in Perl 5.8, PERL_IMPLICIT_CONTEXT and MULTIPLICITY have been synonymous and used interchangeably. To simplify the code, all instances of PERL_IMPLICIT_CONTEXT have been replaced with MULTIPLICITY.

PERL_IMPLICIT_CONTEXT will remain defined for compatibility with XS modules. So like, don't panic, your old XS still vibes. 💅

The API constant formerly named G_ARRAY, indicating list context, has now been renamed to a more accurate G_LIST. A compatibility macro G_ARRAY has been added to allow existing code to work unaffected. New code should be written using the new constant instead. This is supported by Devel::PPPort version 3.63.
Macros have been added to perl.h to facilitate version comparisons: PERL_GCC_VERSION_GE, PERL_GCC_VERSION_GT, PERL_GCC_VERSION_LE and PERL_GCC_VERSION_LT.

Inline functions have been added to embed.h to determine the position of the least significant 1 bit in a word: lsbit_pos32 and lsbit_pos64.

Perl_ptr_table_clear has been deleted. This has been marked as deprecated since v5.14.0 (released in 2011), and is not used by any code on CPAN. It's giving ancient history, periodt.
Added new boolean macros and functions. See "Stable boolean tracking" for related information and perlapi for documentation.
- sv_setbool
- sv_setbool_mg
- SvIsBOOL
Added 4 missing functions for dealing with RVs:
- sv_setrv_noinc
- sv_setrv_noinc_mg
- sv_setrv_inc
- sv_setrv_inc_mg
xs_handshake()'s two failure modes now provide distinct messages. No more which one is it energy. 😭
Memory for hash iterator state (struct xpvhv_aux) is now allocated as part of the hash body, instead of as part of the block of memory allocated for the main hash array.
A new phase_name() interface provides access to the name for each interpreter phase (i.e., PL_phase value).
The pack behavior of U has changed for EBCDIC.
New equality-test functions sv_numeq and sv_streq have been added, along with ..._flags-suffixed variants. These expose a simple and consistent API to perform numerical or string comparison which is aware of operator overloading.
Reading the string form of an integer value no longer sets the flag SVf_POK. The string form is still cached internally, and still re-read directly by the macros SvPV(sv) etc (inline, without calling a C function). XS code that already calls the APIs to get values will not be affected by this change. XS code that accesses flags directly instead of using API calls to express its intent might break, but such code likely is already buggy if passed some other values, such as floating point values or objects with string overloading.

This small change permits code (such as JSON serializers) to reliably determine between

a value that was initially written as an integer, but then read as a string

my $answer = 42;
print "The answer is $answer\n";

that same value that was initially written as a string, but then read as an integer

my $answer = "42";
print "That doesn't look right\n"
    unless $answer == 6 * 9;

For the first case (originally written as an integer), we now have:

use Devel::Peek;
my $answer = 42;
Dump ($answer);
my $void = "$answer";
print STDERR "\n";
Dump($answer)

SV = IV(0x562538925778) at 0x562538925788
  REFCNT = 1
  FLAGS = (IOK,pIOK)
  IV = 42

SV = PVIV(0x5625389263c0) at 0x562538925788
  REFCNT = 1
  FLAGS = (IOK,pIOK,pPOK)
  IV = 42
  PV = 0x562538919b50 "42"\0
  CUR = 2
  LEN = 10

For the second (originally written as a string), we now have:

use Devel::Peek;
my $answer = "42";
Dump ($answer);
my $void = $answer == 6 * 9;
print STDERR "\n";
Dump($answer)'

SV = PV(0x5586ffe9bfb0) at 0x5586ffec0788
  REFCNT = 1
  FLAGS = (POK,IsCOW,pPOK)
  PV = 0x5586ffee7fd0 "42"\0
  CUR = 2
  LEN = 10
  COW_REFCNT = 1

SV = PVIV(0x5586ffec13c0) at 0x5586ffec0788
  REFCNT = 1
  FLAGS = (IOK,POK,IsCOW,pIOK,pPOK)
  IV = 42
  PV = 0x5586ffee7fd0 "42"\0
  CUR = 2
  LEN = 10
  COW_REFCNT = 1

(One can't rely on the presence or absence of the flag SVf_IsCOW to determine the history of operations on a scalar.)

Previously both cases would be indistinguishable, with all 4 flags set:

SV = PVIV(0x55d4d62edaf0) at 0x55d4d62f0930
  REFCNT = 1
  FLAGS = (IOK,POK,pIOK,pPOK)
  IV = 42
  PV = 0x55d4d62e1740 "42"\0
  CUR = 2
  LEN = 10

(and possibly SVf_IsCOW, but not always)

This now means that if XS code really needs to determine which form a value was first written as, it should implement logic roughly

if (flags & SVf_IOK|SVf_NOK) && !(flags & SVf_POK)
    serialize as number
else if (flags & SVf_POK)
    serialize as string
else
    the existing guesswork ...

Note that this doesn't cover "dualvars" - scalars that report different values when asked for their string form or number form (such as $!). Most serialization formats cannot represent such duplicity.

The existing guesswork remains because as well as dualvars, values might be undef, references, overloaded references, typeglobs and other things that Perl itself can represent but do not map one-to-one into external formats, so need some amount of approximation or encapsulation.

sv_dump (and Devel::Peek’s Dump function) now escapes high-bit octets in the PV as hex rather than octal. Since most folks understand hex more readily than octal, this should make these dumps a bit more legible. This does not affect any other diagnostic interfaces like pv_display.

🐛 Selected Bug Fixes 🐛

utime() now correctly sets errno/$! when called on a closed handle. Fixing the vibe check on closed handles. ✅
The flags on the OPTVAL parameter to setsockopt() were previously checked before magic was called, possibly treating a numeric value as a packed buffer or vice versa. It also ignored the UTF-8 flag, potentially treating the internal representation of an upgraded SV as the bytes to supply to the setsockopt() system call. (github #18660 <https://github.com/Perl/perl5/issues/18660>)
Only set IOKp, not IOK on $) and $(. This was issue #18955 <https://github.com/Perl/perl5/issues/18955>: This will prevent serializers from serializing these variables as numbers (which loses the additional groups). This restores behaviour from 5.16
Use of the mktables debugging facility would cause perl to croak since v5.31.10; this problem has now been fixed.
makedepend logic is now compatible with BSD make (fixes GH #19046 <https://github.com/Perl/perl5/issues/19046>).
Calling untie on a tied hash that is partway through iteration now frees the iteration state immediately.

Iterating a tied hash causes perl to store a copy of the current hash key to track the iteration state, with this stored copy passed as the second parameter to NEXTKEY. This internal state is freed immediately when tie hash iteration completes, or if the hash is destroyed, but due to an implementation oversight, it was not freed if the hash was untied. In that case, the internal copy of the key would persist until the earliest of

tie was called again on the same hash
The (now untied) hash was iterated (ie passed to any of keys, values or each)
The hash was destroyed.

This inconsistency is now fixed - the internal state is now freed immediately by untie.

As the precise timing of this behaviour can be observed with pure Perl code (the timing of DESTROY on objects returned from FIRSTKEY and NEXTKEY) it's just possible that some code is sensitive to it.

The Internals::getcwd() function added for bootstrapping miniperl in perl 5.30.0 is now only available in miniperl. [github #19122]
Setting a breakpoint on a BEGIN or equivalently a use statement could cause a memory write to a freed dbstate op. [GH #19198 <https://github.com/Perl/perl5/issues/19198>]
When bareword filehandles are disabled, the parser was interpreting any bareword as a filehandle, even when immediately followed by parens.

📜 Errata From Previous Releases 📜

perl5300delta mistakenly identified a CVE whose correct identification is CVE-2015-1592. Oops, a wrong CVE moment. 💀

🕊️ Obituaries 🕊️

Raun "Spider" Boardman (SPIDB on CPAN), author of at least 66 commits to the Perl 5 core distribution between 1996 and 2002, passed away May 24, 2021 from complications of COVID. He will be missed.

David H. Adler (DHA) passed away on November 16, 2021. In 1997, David co-founded NY.pm, the first Perl user group, and in 1998 co-founded Perl Mongers to help establish other user groups across the globe. He was a frequent attendee at Perl conferences in both North America and Europe and well known for his role in organizing Bad Movie Night celebrations at those conferences. He also contributed to the work of the Perl Foundation, including administering the White Camel awards for community service. He will be missed.

✨ Acknowledgements ✨

Okay bestie, gather round, because this is the part where we give credit where credit is SO beyond due. 💖

Perl 5.36.0 is literally about a year of development on top of Perl 5.34.0, and it's packing approximately 250,000 lines of changes across 2,000 files from 82 authors. No cap. That's not a typo, that's a whole era. 👑

And if we don't count the auto-generated files, the docs, and the release tools? Still approximately 190,000 lines of changes to 1,300 .pm, .t, .c and .h files. The way that they just kept going. 😭

Perl keeps flourishing into its fourth decade thanks to a vibrant community of users and developers — and the following people are known to have contributed the improvements that became Perl 5.36.0:

Alyssa Ross
Andrew Fresh
Aristotle Pagaltzis
Asher Mancinelli
Atsushi Sugawara
Ben Cornett
Bernd
Biswapriyo Nath
Brad Barden
Bram
Branislav Zahradník
brian d foy
Chad Granum
Chris 'BinGOs' Williams
Christian Walde (Mithaldu)
Christopher Yeleighton
Craig A. Berry
cuishuang
Curtis Poe
Dagfinn Ilmari Mannsåker
Dan Book
Daniel Laügt
Dan Jacobson
Dan Kogai
Dave Cross
Dave Lambley
David Cantrell
David Golden
David Marshall
David Mitchell
E. Choroba
Eugen Konkov
Felipe Gasper
François Perrad
Graham Knop
H.Merijn Brand
Hugo van der Sanden
Ilya Sashcheka
Ivan Panchenko
Jakub Wilk
James E Keenan
James Raspass
Karen Etheridge
Karl Williamson
Leam Hall
Leon Timmermans
Magnus Woldrich
Matthew Horsfall
Max Maischein
Michael G Schwern
Michiel Beijen
Mike Fulton
Neil Bowers
Nicholas Clark
Nicolas R
Niyas Sait
Olaf Alders
Paul Evans
Paul Marquess
Petar-Kaleychev
Pete Houston
Renee Baecker
Ricardo Signes
Richard Leach
Robert Rothenberg
Sawyer X
Scott Baker
Sergey Poznyakoff
Sergey Zhmylove
Sisyphus
Slaven Rezic
Steve Hay
Sven Kirmess
TAKAI Kousuke
Thibault Duponchelle
Todd Rinaldo
Tomasz Konojacki
Tomoyuki Sadahiro
Tony Cook
Unicode Consortium
Yves Orton
Михаил Козачков

Absolute icons, every single one. 🎀

Real talk though — that list above is almost certainly incomplete, because it's automatically generated from version control history. Specifically, it does not include the names of the (very much appreciated) contributors who reported issues to the Perl bug tracker. So if you filed a bug and you're not up there, know that you're still a legend in our hearts. 🫶

Also, so many of the changes in this version originated in the CPAN modules included in Perl's core. We're grateful to the entire CPAN community for helping Perl to flourish. 🌸

And for a more complete list of all of Perl's historical contributors, please see the AUTHORS file in the Perl source distribution.

🐛 Reporting Bugs

Found something that looks sus? First move: check the perl bug database at <https://github.com/Perl/perl5/issues>. There may also be information at <http://www.perl.org/>, the Perl Home Page.

If you genuinely believe you've got an unreported bug, please open an issue at <https://github.com/Perl/perl5/issues>. And bestie, be sure to trim your bug down to a tiny but sufficient test case — we love a concise queen. 💅

Now listen, if the bug you're reporting has security implications that make it inappropriate to send to a public issue tracker, do NOT just post it. See "SECURITY VULNERABILITY CONTACT INFORMATION" in perlsec for the details on how to report the issue. Protect the vibe, protect the users. 🔒

🫶 Give Thanks

Wanna say thank you to the Perl 5 Porters for the work we've done in Perl 5? You absolutely can, and it's lowkey adorable — just run the perlthanks program:

perlthanks

That'll send an email to the Perl 5 Porters list with your show of thanks. Go be sweet, it costs nothing. 💖

👀 SEE ALSO

The Changes file — for an explanation of how to view exhaustive details on what changed.
The INSTALL file — for how to build Perl.
The README file — for general stuff.
The Artistic and Copying files — for copyright information.

And that's a wrap on the whole delta, bestie — every last crumb of it. This page came from Perl version v5.42.3, dated 2026-08-03, and it's the PERL5360DELTA(1) manual page, so if you ever need to cite it, that's your receipt. 💜 Go write something iconic with Perl 5.36.0. Periodt. ✨

📦 where this page comes from

fedora 43: perl-doc 5.42.3-524.fc43 · (GPL-1.0-or-later OR Artistic-1.0-Perl) AND Unicode-3.0 AND LicenseRef-Fedora-UltraPermissive
fedora 44: perl-doc 5.42.3-525.fc44 · (GPL-1.0-or-later OR Artistic-1.0-Perl) AND Unicode-3.0 AND LicenseRef-Fedora-UltraPermissive
💖 girlified by deepseek-ai/DeepSeek-V4.1-Flash on 2026-10-13: a language model's rewrite of the original, under its terms