PERL5440DELTA(1)

NAME
perldelta - what is new for perl v5.44.0

DESCRIPTION
This document describes differences between the 5.42.0 release and the 5.44.0 release.

Core Enhancements

  Reported argument counts in "method" signatures now account for $self
In previous versions of Perl, the exception message thrown by a "method" subroutine with a signature when it does not receive an appropriate number of arguments to match its declared parameters failed to account for the implied $self parameter, causing the numbers in the message to be 1 fewer than intended.

This has now been fixed, so messages report the correct number of arguments including the object invocant.

  Unicode 17.0 is supported
See <https://www.unicode.org/versions/Unicode17.0.0/>.

  Named Parameters in Signatures
This adds a major new ability to subroutine signatures, allowing callers to pass parameters by name/value pairs rather than by position.

    sub f ($x, $y, :$alpha, :$beta = undef) { ... }

    f( 123, 456, alpha => 789 );

Originally specified in PPC0024 <https://github.com/Perl/PPCs/blob/main/ppcs/ppc0024-signature-named-parameters.md>.

This feature is currently considered experimental, and is described in further detail in "Signatures" in perlsub.

  Multi-variable "foreach" can now use aliased references
Perl version 5.22 introduced reference aliases, allowing a "foreach" loop iteration variable to create new aliases to references. Perl version 5.36 introduced "foreach" loops with multiple variables, consuming more than one input list item on each iteration. New in this version, the two features may now be used together, allowing multiple iteration variables where any of them are permitted to be reference aliases.

    use v5.44;
    use feature qw( refaliasing declared_refs );

    my %hash = (
        one => [1],
        two => [2, 2],
    );

    foreach my ( $key, \@items ) ( %hash ) {
        say "The $key array contains: @items";
    }

Currently both the "refaliasing" and "declared_refs" features remain experimental.

  New source of entropy for PRNG seeding
Perl now uses the getentropy() system call to fetch random bytes suitable for seeding the internal PRNG. Previously Perl would read raw bytes from the /dev/urandom device. Perl now seeds itself in this order (and falls through upon failure):

1.  getentropy() on systems that support this call (Linux, BSD, MacOS)

2.  /dev/urandom on systems that have it

3.  Hash of internal state variables: Unix time, process ID, and pointer value

  Enhanced operation of regular expression patterns under /xx
Experimentally, the "/xx" pattern modifier can allow bracketed character classes (e.g., "[a-zA-Z]" to extend across multiple lines and to contain comments, and to warn you of potential cases where a portion of a pattern inadvertently has been treated as a comment instead of what you intended. This behavior is enabled by use feature "enhanced_xx". See "/x and /xx" in perlre.

Security

  CVE-2026-8376 - Buffer overflow in Perl_study_chunk
Perl_study_chunk in regcomp_study.c checked the size of the joined substring buffer in characters rather than bytes. On 32-bit builds, this can lead to an integer overflow of the size of the buffer leading to out-of-bounds writes.

Incompatible Changes

  Unicode rules are now fully enforced on identifier and regular expression group names.
Before Unicode, Perl accepted any "\w" character in an identifier or other name, except the first character couldn't be a digit. Later, Unicode created two properties that described this. Even later, they found those properties to be insufficient, and created two new similar properties. These are the ones that perl has intended to use since: "\p{XID_Start}" and "\p{XID_Continue}". (The "X" stands for "eXtended" and indicates these are the more modern versions.)

(And even later, long after Perl identifier rules were formed using the above properties, Unicode added recommendations to further restrict legal identifier names. These were added to counter cases where, for example, programmers snuck code past reviewers using characters that look like other ones. The two properties are "Identifier_Status" and "Identifier_Type". See <https://www.unicode.org/reports/tr39/>. Perl currently doesn't do anything with these, except to furnish you the ability to use them in regular expressions.)

We soon discovered that there were 14 characters that match "XID_Start" and "XID_Continue" that don't also match "\w". To avoid breaking code that had long relied on "\w", we chose to not add those to the list of acceptable identifier characters.

It turns out that there are about 160 characters that match "\w" but not the Unicode "XID" properties. Thus they are illegal according to Unicode. Those are now explicitly forbidden in both Perl identifiers and regular expression group names. Previously, it was likely that their use in identifiers wouldn't work anyway; they could be accepted initially as legal, but other code would later reject them, but with a message that had nothing to do with the underlying problem. However group names in regular expression patterns could contain illegal continuation characters and have a higher probablility of not being caught. That is now changed.

Only programs that do "use utf8" can be affected, and then only characters that appear in the 2nd or later positions of the name. The characters that an identifier name can begin with are unchanged.

130 of the now unacceptable characters are 5 sets of 26 Latin letters that are enclosed by some shape, such as CIRCLED LATIN CAPITAL LETTER N. Another 8 are generic modifiers that add shapes around other characters; 5 are modifiers to Cyrillic numbers; and 16 are Arabic ligatures and isolated forms. The other two are GREEK YPOGEGRAMMENI and VERTICAL TILDE.

Deprecations

•   Using "goto" to jump into the body of a loop or other block construct from outside is no longer permitted. [GH #23618 <https://github.com/Perl/perl5/issues/23618>]

•   "m/...[...].../xx" has new restrictions

    Using an unescaped "#" or literal vertical space is now deprecated in a regular expression bracketed character class that is compiled with the "/xx" modifier. These still work, but deprecation warnings will be generated unless turned off or the constructs are cured as follows.

    •   Escape a "#" by preceding it with a backslash, like in

         m/ [ % \# ( ) ] /xx

    •   Use constructs like "\n" instead of literal vertical space.

Performance Enhancements

•   Simple (non-overflowing) addition ("+"), subtraction ("-") and multiplication ("*") of integers are slightly sped up, as long as sufficient underlying C compiler support is available.

•   Populating a hash from a list of key/value pairs, when the keys are constant string operands known at compile time, is commonly now faster. [GH #24228 <https://github.com/Perl/perl5/issues/24228>]

Modules and Pragmata

  Updated Modules and Pragmata

•   Archive::Tar has been upgraded from version 3.04 to 3.12.

•   attributes has been upgraded from version 0.36 to 0.37.

•   B has been upgraded from version 1.89 to 1.92.

•   B::Concise has been upgraded from version 1.007 to 1.012.

•   B::Deparse has been upgraded from version 1.85 to 1.89.

•   charnames has been upgraded from version 1.50 to 1.51.

•   Compress::Raw::Bzip2 has been upgraded from version 2.213 to 2.218.

•   Compress::Raw::Zlib has been upgraded from version 2.213 to 2.222.

•   Config::Perl::V has been upgraded from version 0.38 to 0.39.

•   CPAN::Meta has been upgraded from version 2.150010 to 2.150013.

•   CPAN::Meta::Requirements has been upgraded from version 2.143 to 2.145.

•   DB_File has been upgraded from version 1.859 to 1.860.

•   Encode has been upgraded from version 3.21 to 3.24.

•   English has been upgraded from version 1.11 to 1.12.

•   Errno has been upgraded from version 1.38 to 1.39.

•   experimental has been upgraded from version 0.035 to 0.036.

•   ExtUtils::CBuilder has been upgraded from version 0.280242 to 0.280243.

•   ExtUtils::MakeMaker has been upgraded from version 7.76 to 7.78.

•   ExtUtils::Miniperl has been upgraded from version 1.14 to 1.15.

•   ExtUtils::ParseXS has been upgraded from version 3.57 to 3.63.

•   ExtUtils::Typemaps has been upgraded from version 3.57 to 3.63.

•   feature has been upgraded from version 1.97 to 2.02.

•   File::Copy has been upgraded from version 2.41 to 2.43.

•   File::Fetch has been upgraded from version 1.04 to 1.08.

•   File::Glob has been upgraded from version 1.42 to 1.44.

•   File::Spec has been upgraded from version 3.94 to 3.95.

•   File::stat has been upgraded from version 1.14 to 1.15.

•   File::Temp has been upgraded from version 0.2311 to 0.2312.

•   Filter::Simple has been upgraded from version 0.96 to 0.97.

•   Filter::Util::Call has been upgraded from version 1.64 to 1.65.

•   Getopt::Std has been upgraded from version 1.14 to 1.15.

•   HTTP::Tiny has been upgraded from version 0.090 to 0.096.

•   IO has been upgraded from version 1.55 to 1.56.

•   IO::Compress has been upgraded from version 2.213 to 2.220.

•   IO::Socket::IP has been upgraded from version 0.43 to 0.44.

•   Math::BigInt has been upgraded from version 2.005002 to 2.005003.

•   Module::CoreList has been upgraded from version 5.20250702 to 5.20260722.

•   Module::Metadata has been upgraded from version 1.000038 to 1.000039.

•   mro has been upgraded from version 1.29 to 1.30.

•   Net::Ping has been upgraded from version 2.76 to 2.77.

•   Opcode has been upgraded from version 1.69 to 1.71.

•   overloading has been upgraded from version 0.02 to 0.03.

•   PerlIO::via has been upgraded from version 0.19 to 0.21.

•   Pod::Html has been upgraded from version 1.35 to 1.36.

•   Pod::Simple has been upgraded from version 3.45 to 3.48.

•   POSIX has been upgraded from version 2.23 to 2.26.

•   Scalar::Util has been upgraded from version 1.68_01 to 1.70.

•   SelectSaver has been upgraded from version 1.02 to 1.03.

•   SelfLoader has been upgraded from version 1.28 to 1.29.

•   Socket has been upgraded from version 2.038 to 2.041.

•   Storable has been upgraded from version 3.37 to 3.41.

•   Term::Table has been upgraded from version 0.024 to 0.028.

•   Test::Harness has been upgraded from version 3.50 to 3.52.

•   Test::Simple has been upgraded from version 1.302210 to 1.302219.

•   Text::Balanced has been upgraded from version 2.06 to 2.07.

•   threads has been upgraded from version 2.43 to 2.45.

•   threads::shared has been upgraded from version 1.70 to 1.73.

•   Time::HiRes has been upgraded from version 1.9778 to 1.9780.

•   Time::Piece has been upgraded from version 1.36 to 1.41.

•   Unicode::UCD has been upgraded from version 0.81 to 0.83.

•   utf8 has been upgraded from version 1.27 to 1.29.

•   version has been upgraded from version 0.9933 to 0.9934.

•   warnings has been upgraded from version 1.74 to 1.78.

•   XS::APItest has been upgraded from version 1.43 to 1.50.

•   XS::Typemap has been upgraded from version 0.20 to 0.22.

Documentation

  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>.

Additionally, the following selected changes have been made:

perlapi

•   Auto-generation of this document now includes the line number of the source code, as well as its documentation.

perlexperiment

•   New entry for "New object system and "class" syntax".

•   perlapi now contains information about how to find what release of Perl first contained an API element.

perlxs

•   The reference manual for writing Perl XS code has been completely rewritten and modernized. It is about twice the size of the old file, and promotes more modern XS syntax, such as ANSI signatures.

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 perldiag.

  Changes to Existing Diagnostics

•   Use of uninitialized value%s

    This warning was issued in the reverse order (right-to-left) when both operands of a binary operator are uninitialized values. This is now fixed to be consistent with evaluation order of operands.

•   Certain diagnostics about byte sequences that are supposed to comprise a UTF-8 encoded character, but that are invalid in some way, now don't include bytes irrelevant to that determination. An example is

    old message
        Malformed UTF-8 character: "\xc1\x27" (any UTF-8 sequence that starts with "\xc1" is overlong which can and should be represented with a different, shorter sequence)

    new message
        Malformed UTF-8 character: "\xc1" (any UTF-8 sequence that starts with "\xc1" is overlong which can and should be represented with a different, shorter sequence)

    In this case the "\xc1" is all that is needed to make the sequence invalid. Whatever comes after it is irrelevant (in this case, "\x27"), and including it in the message might lead the reader to think that it somehow does matter.

•   The error "Unrecognised parameters for "%s" constructor: %s" has been changed to "Unrecognized parameters for "%s" constructor: %s".

•   Variables whose name started with "^_" were incorrectly shown in diagnostics with a literal "Ctrl-_" (which is an invisible ASCII character) in their name.

    The names of variables whose names begin with a caret and are longer than two characters are now wrapped in braces, just as they have to be in the source code.

    Therefore, using an undefined "${^_FOO}" will now correctly warn with "Use of uninitialized value ${^_FOO}", instead of the earlier "Use of uninitialized value $FOO" (with a literal "Ctrl-_" after the dollar sign).

    [GH #24135 <https://github.com/Perl/perl5/issues/24135>]

•   Calling the "import" method on a package with no "import" method now produces a regular warning rather than a deprecation warning or error.

    Since Perl 5.39.1, calling "import" with arguments on a package without such a method has triggered a deprecation warning. In Perl 5.43.6, this deprecation was promoted into an error. This broke a significant amount of code while providing very little advantage over the warning. This fatal error has been converted back to a warning, with its deprecation status removed. There are no longer any plans to make this fatal in the future. The category for this warning is "missing_import" and it is enabled by default.

  New Diagnostics
New Errors

•   Can't redeclare catch variable as "%s"

    (F) A "my", "our" or "state" keyword was used with the exception variable in a "catch" block:

        try { ... }
        catch (my $e) { ... }
        # or catch (our $e) { ... }
        # or catch (state $e) { ... }

    This is not valid syntax. "catch" takes a bare variable name, which is automatically lexically declared. [GH #23222 <https://github.com/Perl/perl5/issues/23222>]

•   Use of "goto" to jump into a construct is no longer permitted

    (F) You have used "goto LABEL;" or "goto EXPR;" in an attempt to jump into the body of a loop or other block construct from the outside. As of Perl 5.44, this throws an exception.

•   \x{%X} is a \w char that isn't valid in a name "%s"

    In most cases where this message now appears, an error would have occurred anyway, but the text would not have been helpful in finding the problem.

New Warnings

•   Possible attempt to escape whitespace in qw() list

    (W qw) qw() lists contain items separated by whitespace; contrary to what some might expect, backslash characters cannot be used to "protect" whitespace from being split, but are instead treated as literal data.

    Note that this warning is only emitted when the backslash is followed by actual whitespace (that "qw" splits on).

Configuration and Compilation

•   C23 <stdckdint.h> and associated macros are now used if available.

•   It is now possible to pass to Configure the values dealing with POSIX locale categories, overriding its automatic calculation of these. This enables cross-compilation to work. The easiest way to do this is to extract the C program that does the calculation from Configure and then run it on the target machine, and then pass the values it outputs to Configure on the other machine. Porting/Glossary has examples. [GH #22992 <https://github.com/Perl/perl5/issues/22992>]

•   The "PERL_CREATE_GVSV" configuration macro has been removed. It was almost undocumented and it has been disabled by default since Perl 5.10.0. Its purpose was to force all GVs to initialize their SV slot on creation. [GH #24177 <https://github.com/Perl/perl5/issues/24177>]

Testing
Tests were added and changed to reflect the other additions and changes in this release. Furthermore, these changes were made:

•   Karl Williamson gave a talk at TPRC 2025 asking people to contribute tests to find old issues that are no longer a problem, and todo tests to reflect reproduction cases for known outstanding bugs. (video link <https://www.youtube.com/watch?v=CwX4Xsf5y5E>) It gained renewed interest this year, leading to an uptick in test submissions from new authors, for which we are extremely grateful.

•   When testing embedding, add a sanity check to ensure the "libperl" we link against matches the perl we are building. [GH #22125 <https://github.com/Perl/perl5/issues/22125>]

Platform Support

  Platform-Specific Notes

Windows
    •   Fix builds with "USE_IMP_SYS" defined but "USE_ITHREADS" not defined.

    •   A compilation error in unthreaded builds using MSVC introduced in Perl 5.43.5 has been fixed. [GH #23952 <https://github.com/Perl/perl5/issues/23952>]

OpenBSD
    •   When testing embedding, ensure we link against the correct static libperl. [GH #22125 <https://github.com/Perl/perl5/issues/22125>]

AIX
    •   Thread-safe locale handling has been turned off on all releases due to apparent bugs in the underlying operating system support.

    •   The ibm-clang/ibm-clang_r IBM Open XL C/C++ compiler is now supported for AIX 7.2 and 7.3. This is the recommended compiler to use when compiling Perl on these versions of AIX.

Internal Changes

•   The XS parser, ExtUtils::ParseXS, has been further extensively restructured internally. Most of these changes shouldn't be visible externally, but might affect XS code which was using invalid or unsupported syntax. Several minor bug-fixes were included.

•   Removed the deprecated (since 5.32) functions sv_locking() and "sv_unlocking".

•   "Perl_expected_size" has been added as an experimental stub macro. The intention is to build on this such that it can be passed a size in bytes, then returns the interpreter's best informed guess of what actual usable allocation size would be returned by the malloc implementation in use.

    This would help with sizing allocations such that SvLEN is more accurate and not trying to shrink string buffers to save size when the intended saving is unrealistic.

•   "SvPV_shrink_to_cur" has been revised to include a byte for copy-on-write (COW), so that the resulting string could be COWed in the future.

    It also now uses "Perl_expected_size", compared against the current buffer size, and does not try to do a reallocation if the requested memory saving is unrealistic.

•   sv_vcatpvfn_flags() now substitutes the Unicode REPLACEMENT CHARACTER for malformed input. Previously it used the NUL character.

•   For core Perl maintainers, the syntax of embed.fnc has been extended. Every function, foo(), named in this file has generated for it a macro named "PERL_ARGS_ASSERT_FOO". The macro expands to assert() calls that do basic sanity checking for each argument to foo() that we currently deem as being appropriate to have such checking. (That means that many arguments are not checked, and that the generated macro may currently expand to nothing.) With this release, you can add assert() statements yourself to embed.fnc that will be incorporated into the generated macro, beyond the system-generated ones. Comments and examples in embed.fnc give details.

•   A new function "valid_utf8_to_uv" has been added. This is synonymous with "valid_utf8_to_uvchr"; its reason for existence is to have consistent spelling with the names of the other functions that translate from UTF-8, so you don't have to remember a different spelling.

•   ""newSVsv_flags_NN"" in perlapi is a new function for creating a new SV and assigning the value(s) of an existing SV to it.

    Historically, "Perl_newSVsv_flags" and "Perl_sv_mortalcopy_flags" would pass a new SV head and the original SV to "Perl_sv_setsv_flags". However, the latter contains many branches of no relevance to a fresh SV, so they now make use of the new function to streamline the process.

    "Perl_newSVsv_flags" is now essentially a NULL pointer check and wrapper around the new function, so has been moved into sv_inline.h.

•   ""STATIC_ASSERT_DECL"" in perlapi and "STATIC_ASSERT_STMT" are like assert(), but are evaluated at compile time. That means their argument must be a constant expression that can be verified by the compiler, and so they effectively have no cost, not appearing in the code that gets executed. These were added in v5.28, but not until now have we opened their use up to XS writers. At the same time, a new variant has been added, "STATIC_ASSERT_EXPR" which is suitable for use in an expression, such as a comma expression in a C macro.

•   "Perl_sv_backoff", which undoes the "OOK" string offset mechanism now only moves the string buffer contents to the start of the buffer if SvOK(sv) is true. Historically, the buffer contents were always moved, but if the buffer contents are defunct and no longer required, doing that incurs an unnecessary cost proportional to the size of the shifted contents.

    (The assumption in this change is that SvOK(sv) is a valid indicator of whether the string buffer contents are "live" or not.)

    See [GH #23967 <https://github.com/Perl/perl5/issues/23967>] for an example of where such a copy was noticeable.

•   Fixed a bug in the "sv_numeq" in perlapi API where values with numeric ("0+") overloading but not equality or numeric comparison overloading would always be compared as floating point values. This could lead to large integers being reported as equal when they weren't.

•   Fixed a bug in "sv_numeq" in perlapi where the "SV_SKIP_OVERLOAD" flag would skip operator overloading, but would still honor numeric ("0+") overloading.

•   Added "sv_numne" in perlapi, sv_numle, sv_numlt, sv_numge, sv_numgt and "sv_numcmp" in perlapi APIs that perform numeric comparison in the same way perl does, including overloading. Separate APIs for each comparison are needed to invoke their corresponding overload when needed. Inspired by [GH #23918 <https://github.com/Perl/perl5/issues/23918>]

    This also extends the sv_numeq API to support "SV_FORCE_OVERLOAD".

•   Added the "AMGf_force_scalar" flag to the ""amagic_call"" in perlapi API to force scalar context for overload calls.

•   Added the "AMGf_force_overload" flag to the ""amagic_call"" in perlapi API to allow forcing overloading to be honored even in the context of "no overloading;".

•   The "SvFLAGS" bits used by SvPCS_IMPORTED() and SvOOK() have now been merged into the same position, thus freeing up a flags bit for possible future purposes. This merge is distinguished by the fact that the "PCS_IMPORTED" behaviour is only used on references (when "SvROK" is true), whereas the "OOK" only applies to string buffers (when "SvROK" is false).

    This change shouldn't affect any "XS" module code that is using the test macros correctly, though might cause confusion to code that attempts to analyse "SvFLAGS" bits directly outside of the helper macros.

•   An upper limit has been applied to the multiplier operand of the repetition operator. Constant folding will not be attempted if the operand is a numerical constant above "PERL_FOLD_REPEAT_LIMIT". See [GH #20586 <https://github.com/Perl/perl5/issues/20586>] and [GH #23561 <https://github.com/Perl/perl5/issues/23561>] for background.

•   Dedicated check functions "Perl_ck_anonhash" and "Perl_ck_aassign" have been added and are used to hekify some "OP_CONST" hash keys at compile time. [GH #24228 <https://github.com/Perl/perl5/issues/24228>]

•   "Perl_check_hash_fields_and_hekify", partly called as a compile-time optimization, no longer preemptively converts an NV to a HEK if the compile time and run time locales could differ. [GH #24252 <https://github.com/Perl/perl5/issues/24252>]

•   "Perl_check_hash_fields_and_hekify", partly called as a compile-time optimization, no longer preemptively converts a UTF-8 string to a HEK when this will downgrade the string to a single byte representation.

    At present, multiple functions inadequately handle the flag used to denote when a key originally had UTF-8 encoding, making it impossible to restore the encoding when keys are extracted from a hash (using "keys" for example).

    Tracking of UTF-8 origins can hopefully be improved in the next development cycle, allowing for preemptive conversion of all UTF-8 strings once again. [GH #24266 <https://github.com/Perl/perl5/issues/24266>] [GH #24287 <https://github.com/Perl/perl5/issues/24287>]

•   The macro ""fromCTRL"" in perlapi has been added to be the inverse of the existing ""toCTRL"" in perlapi. toCTRL('A') yields 1 (the control character "SOH" on all platforms Perl works on); fromCTRL(1) yields 'A'.

•   When a UTF-8 constant string was used as the hash key in an insert operation, such as "$hash{'über maus'} = 1;", and the string could be converted into a single byte representation, the flag noting the original encoding ("HVhek_WASUTF8") was not always retained.

    When this occurred, the relevant scalars returned by "keys %hash" would not be in the original, expected UTF-8 encoding.

    The original encoding is now captured and propagated. [GH #24266 <https://github.com/Perl/perl5/issues/24266>]

•   When a constant IV or NV was used as a hash key, such as in "my %hash = ( 42 => 0 );", and was preemptively stringified into a hash key, the fact that the numerical value came first was lost. This unintentionally modified deparse output for such keys.

    The numerical values are now carried across, and flags on the key variable reflect the original data type.

    Note: This now preserves the form of constant keys supplied to tied hashes in list assignments. [GH #24302 <https://github.com/Perl/perl5/issues/24302>]

•   "defer_error" in perlapi, formerly known as "qerror", and "op_clear" in perlapi are now part of the API.

    Perl 5.43.2 hid Perl non-API function declarations unless you defined "PERL_EXT" or "PERL_CORE", so these non-API functions no longer had visible declarations.

    A small number of CPAN modules used these APIs and a stricter GCC 15 started enforcing C99 disallowing implicit function declarations, producing build failures.

    Added qerror() as a deprecated public alias for defer_error() to allow existing users of that name to build successfully.

    [GH #23676 <https://github.com/Perl/perl5/issues/23676>]

Selected Bug Fixes

•   When both operands of arithmetic operators ("+", "-", etc.) are overloaded objects which have no method for that operator but have a "0+" method and the "fallback" option set to TRUE, perl will normally call the "0+" method for the left operand first and then call one for the right operand, i.e. in the same order as operand evaluation. But if "use integer;" is in effect, the "0+" methods used to be called in wrong (reverse) order.

•   Certain constructs involving a two-variable "for" loop would crash the perl compiler in v5.42.0:

        # Two-variable for loop over a list returned from a method call:
        for my ($x, $y) (Some::Class->foo()) { ... }
        for my ($x, $y) ($object->foo()) { ... }

    and

        # Two-variable for loop over a list returned from a call to a
        # lexical(ly imported) subroutine, all inside a lexically scoped
        # or anonymous subroutine:
        my sub foo { ... }
        my $fn = sub {
            for my ($x, $y) (foo()) { ... }
        };

        use builtin qw(indexed);  # lexical import!
        my sub bar {
            for my ($x, $y) (indexed(...)) { ... }
        }

    These have been fixed. [GH #23405 <https://github.com/Perl/perl5/issues/23405>]

•   Several error conditions in the "pack" and "unpack" operations were not detected and now are.

•   INTERFACE keyword in XS

    INTERFACE keyword in XS

    Fixed a couple of issues with the INTERFACE keyword in XS.

    [GH #23640 <https://github.com/Perl/perl5/issues/23640>]

•   "&CORE::__CLASS__" no longer returns invalid results

    "CORE::__CLASS__" would work as expected when used as a bareword or aliased:

        use feature qw(class);
        class Foo {
            BEGIN { *cls = \&CORE::__CLASS__; }
            method bar() {
                my $class1 = CORE::__CLASS__;  # ok
                my $class2 = cls;              # ok
            }
        }

    But when called with an ampersand ("&CORE::__CLASS__()") or through a reference ("my $ref = \&CORE::__CLASS__; $ref->()"), it would return unrelated strings. These runtime calls have been fixed to throw an error of the form "&CORE::__CLASS__ cannot be called directly" instead of silently returning incorrect results.

    [GH #23737 <https://github.com/Perl/perl5/issues/23737>]

•   parse_subsignature() can now handle empty subroutine signatures

    Previously, calling the parse_subsignature() API function with an empty signature would cause a "Syntax error" failure, requiring code which calls it to detect the special case and take appropriate steps. This is now fixed, returning the same optree that the parser would yield for a regular empty signature during normal parse time.

    [GH #17689 <https://github.com/Perl/perl5/issues/17689>]

•   The "-CA" flag (or equivalently, the "PERL_UNICODE=A" environment setting) tells perl to treat command-line arguments as UTF-8 strings. (See perlrun for details.) However, this did not extend to the global variables implicitly created by the "-s" option:

     $ perl -CA -s -e 'printf "%vx\n", $_ for $foo, $ARGV[0]' -- -foo=é é
     c3.a9
     e9

    Here $foo would end up containing the two-byte UTF-8 representation of "LATIN SMALL LETTER E WITH ACUTE", but $ARGV[0] would contain a single codepoint corresponding to U+00E9.

    This has been fixed: If "-CA" is in effect, options parsed by "-s" are treated as UTF-8, too. In the example above, $foo and $ARGV[0] now both contain chr(0xE9). [GH #23377 <https://github.com/Perl/perl5/issues/23377>]

•   We have long claimed to support identifiers up to about 255 characters long. However this was actually true only for identifiers that consisted of only ASCII characters. The real upper limit was as few as 64 characters for identifiers written in other languages, for example, Chinese or Osage. Now an identifier in any language may contain at least 255 characters.

•   Fixed parsing of array names starting with a digit in double-quotish context under "use utf8;".

•   "use 5.42" now turns on "use source::encoding "ascii"" for the remainder of the line (besides subsequent lines). [GH #23881 <https://github.com/Perl/perl5/issues/23881>]

•   Since 5.32.0, the second branch of a ternary condition operator wasn't getting the correct autovivification context applied. For example in something like

        @{ $cond ? $h{foo} : $h{bar} } = ...;

    the first branch would correctly autovivify $h{foo} to an array ref, but the second branch might incorrectly autovivify $h{bar} to a hash ref. [GH #18669 <https://github.com/Perl/perl5/issues/18669>].

•   Don't warn about jumping into a construct if we're DIE-ing [GH #23922 <https://github.com/Perl/perl5/pull/23922>].

•   Regexes which include both a sub-pattern (e.g. "(??{...})" or "(?&FOO)") and a cut (i.e. "(?>...)") could sometimes cause a premature scope exit in other code during a match. For example, in something like "(?{ local $x = ... })", the "local" might have been unwound before the pattern has finished matching. [GH #16197 <https://github.com/Perl/perl5/issues/16197>]

•   "DB::sub" is not meant to be called for sub calls from the DB package, but calls to overloaded subs for overloaded values used in the DB package would result in calls to DB::sub. Fixed the check for the current package in amagic_call(). [GH #24001 <https://github.com/Perl/perl5/issues/24001>].

•   Fix parsing of hexadecimal floating-point numbers whose significand (aka "mantissa") values are too large to fit in UV range. Such literals (for example, "0x1234567890.1p+0" for 32-bit IV/UV platform, or "0x1234567890_1234567890.1p+0" for 64-bit IV/UV) used to be parsed incorrectly.

•   Perl 5.42.0 does not handle the transition to/from daylight savings time properly. The time and/or timezone can be off by an hour in the intervals surrounding such transitions. This is a regression from earlier releases, and is now fixed. This bug was evident from perl space in the "strftime" in POSIX function, and in XS code with any of "my_strftime" in perlapi, "sv_strftime_ints" in perlapi, or "sv_strftime_tm" in perlapi.

•   sort() optimizes common comparisons from calling the OP tree for a comparison block into a call to a C function. The C function used for overloaded numeric comparisons did not handle the case where there was no comparison overload but there was a numeric ("0+") overload correctly, losing precision for large overloaded integer arguments that are not exactly representable as a Perl floating point value (NV). [GH #23956 <https://github.com/Perl/perl5/issues/23956>]

•   When a scalar variable used as the target of a filehandle is "undef"'ed while being output, garbage bytes would be left in that scalar. [GH #24008 <https://github.com/Perl/perl5/issues/24008>]

    •   Additionally, there was a case that would expose garbage bytes in the target scalar or even trigger a segmentation fault when that scalar is output on it (as in "open $fh, '>', \$str; print $fh $str;"). This is also fixed. [GH #24199 <https://github.com/Perl/perl5/issues/24199>]

•   close(STDOUT) when "STDOUT" has been opened as a pipe will now properly wait for the child to exit on Windows. [GH #4106 <https://github.com/Perl/perl5/issues/4106>]

•   Calling an XSUB via goto in scalar context, where the XSUB didn't return exactly one value, could result in the return of the wrong number of items, leading to potential stack corruption. For example:

        sub wrap { goto \&an_xsub_which_returns_no_values }
        $ret = wrap();

    [GH #24212 <https://github.com/Perl/perl5/issues/24212>]

•   On debugging perls, instantiating a class with an array field with an empty initializer list would abort with an error:

        class Foo {
            field @bar = ();
        }
        Foo->new();

    Error message: "perl: inline.h:194: Perl_av_new_alloc: Assertion `size > 0' failed."

    This has been fixed. [GH #24246 <https://github.com/Perl/perl5/issues/24246>]

•   Refassigning to a class field in a method could result in the SV for that field being released when the method exited. The next access to that field could result in a crash or an assertion, or if the freed SV had been re-used, random data. Discussed in [GH #24187 <https://github.com/Perl/perl5/issues/24187>]

Known Problems
None

Obituary
"WELL VOLUNTEERED!" echoed across conference rooms and IRC channels. Matt S. Trout's battle cry that transformed reluctant volunteers into community leaders.

With profound sadness, we announce Matt's passing. Since the early 2000s, Matt shaped Perl through sheer force of will: IRC operator, PAUSE administrator, Shadowcat Systems co-founder, architect of DBIx::Class. His opinions came wrapped in profanity and delivered at maximum volume. He suffered no fools and grew to sometimes realize he should apologize. Yet this same abrasive exterior protected fierce dedication to mentoring, developers he harangued into volunteering now lead the community themselves. Matt's deliberately mind-bending code pushed Perl forward. Every modern Perl developer touches his legacy daily.

Well volunteered, Matt. Rest in peace.

Acknowledgements
Perl 5.44.0 represents approximately 12 months of development since Perl 5.42.0 and contains approximately 270,000 lines of changes across 1,300 files from 71 authors.

Excluding auto-generated files, documentation and release tools, there were approximately 110,000 lines of changes to 860 .pm, .t, .c and .h files.

Perl continues to flourish into its fourth decade thanks to a vibrant community of users and developers. The following people are known to have contributed the improvements that became Perl 5.42.1:

Alexander Karelas, Aristotle Pagaltzis, Arne Johannessen, Bartosz Jarzyna, Branislav Zahradník, brian d foy, Chad Granum, Chris 'BinGOs' Williams, Chris Prather, Christian Hansen, Craig A. Berry, Dagfinn Ilmari Mannsåker, Dan Book, Dan Church, Daniel Dragan, Daniel Laügt, Daniel Tang, Dan Kogai, Dave Cross, David Mitchell, Dmitrii Kuvaiskii, E. Choroba, Ed J, Elvin Aslanov, Eric Herman, Eugen Konkov, Graham Knop, Harald Jörg, H.Merijn Brand, Igor Todorovski, James Cook, James E Keenan, James Raspass, Jörg Thomas, Karen Etheridge, Karl Williamson, Leon Timmermans, Lukas Mai, Marc Reisner, Masahiro Iuchi, Matthew Horsfall, Maxim Vuets, Max Maischein, Nicolas R, Olaf Alders, Paul Evans, Paul Marquess, Peter John Acklam, Philippe Bruhat (BooK), Ricardo Signes, Richard Leach, Robert Rothenberg, Ryan Carsten Schmidt, Samuel Smith, Samuel Young, Scott Baker, Sevan Janiyan, Shirakata Kentaro, Sisyphus, Stan Ulbrych, Stefan Adams, Štěpán Němec, Steve Hay, TAKAI Kousuke, Thibault Duponchelle, Toby Inkster, Tomasz Konojacki, Tom Wyant, Tony Cook, Unicode Consortium, Yitzchak Scott-Thoennes.

The list above is almost certainly incomplete as it is automatically generated from version control history. In particular, it does not include the names of the (very much appreciated) contributors who reported issues to the Perl bug tracker.

Many of the changes included 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.

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

Reporting Bugs
If you find what you think is a bug, you might check the perl bug database at <https://github.com/Perl/perl5/issues>. There may also be information at <https://www.perl.org/>, the Perl Home Page.

If you believe you have an unreported bug, please open an issue at <https://github.com/Perl/perl5/issues>. Be sure to trim your bug down to a tiny but sufficient test case.

If the bug you are reporting has security implications which make it inappropriate to send to a public issue tracker, then see "SECURITY VULNERABILITY CONTACT INFORMATION" in perlsec for details of how to report the issue.

Give Thanks
If you wish to thank the Perl 5 Porters for the work we had done in Perl 5, you can do so by running the "perlthanks" program:

    perlthanks

This will send an email to the Perl 5 Porters list with your show of thanks.

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.