PERL5360DELTA(1) Perl Programmers Reference Guide PERL5360DELTA(1)

PERL5360DELTA(1) Perl Programmers Reference Guide PERL5360DELTA(1) #

PERL5360DELTA(1) Perl Programmers Reference Guide PERL5360DELTA(1)

NNAAMMEE #

 perl5360delta - what is new for perl v5.36.0

DDEESSCCRRIIPPTTIIOONN #

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

CCoorree EEnnhhaanncceemmeennttss “"uussee vv55..3366"” 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 _d_i_s_a_b_l_e_s 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.

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

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

UUnniiccooddee 1144..00 iiss ssuuppppoorrtteedd See https://www.unicode.org/versions/Unicode14.0.0/ for details.

rreeggeexx sseettss aarree nnoo lloonnggeerr ccoonnssiiddeerreedd eexxppeerriimmeennttaall 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.

VVaarriiaabbllee lleennggtthh llooookkbbeehhiinndd iiss mmoossttllyy nnoo lloonnggeerr ccoonnssiiddeerreedd eexxppeerriimmeennttaall 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.

SSIIGGFFPPEE nnoo lloonnggeerr ddeeffeerrrreedd 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.

SSttaabbllee bboooolleeaann ttrraacckkiinngg 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.

iitteerraattiinngg oovveerr mmuullttiippllee vvaalluueess aatt aa ttiimmee ((eexxppeerriimmeennttaall)) 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.

bbuuiillttiinn ffuunnccttiioonnss ((eexxppeerriimmeennttaall)) 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 eexxppeerriimmeennttaall.  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. #

“"ddeeffeerr"” bblloocckkss ((eexxppeerriimmeennttaall)) 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 _c_o_n_t_a_i_n_i_n_g 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.

ttrryy//ccaattcchh ccaann nnooww hhaavvee aa “"ffiinnaallllyy"” bblloocckk ((eexxppeerriimmeennttaall)) 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.

nnoonn--AASSCCIIII ddeelliimmiitteerrss ffoorr qquuoottee--lliikkee ooppeerraattoorrss ((eexxppeerriimmeennttaall)) 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.

@@ iiss nnooww eexxppeerriimmeennttaall wwiitthhiinn ssiiggnnaattuurreedd ssuubbss Even though subroutine signatures are now stable, use of the legacy arguments array (@_) with a subroutine that has a signature _r_e_m_a_i_n_s 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.

IInnccoommppaattiibbllee CChhaannggeess AA pphhyyssiiccaallllyy eemmppttyy ssoorrtt iiss nnooww aa ccoommppiillee--ttiimmee eerrrroorr @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".

DDeepprreeccaattiioonnss “"uussee VVEERRSSIIOONN"” ((wwhheerree VVEERRSSIIOONN iiss bbeellooww vv55..1111)) aafftteerr “"uussee vv55..1111"” iiss ddeepprreeccaatteedd When in the scope of “use v5.11” or later, a “use vX” line where _X is lower than v5.11 will now issue a warning:

     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";

 This is because the Perl team plans to change the behavior in this case.
 Since Perl v5.12 (and parts of v5.11), strict is enabled _u_n_l_e_s_s _i_t _h_a_d
 _p_r_e_v_i_o_u_s_l_y _b_e_e_n _d_i_s_a_b_l_e_d.  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
 _a_l_w_a_y_s enable strict for versions v5.12 and later.

 Code which wishes to mix versions in this manner should use lexical
 scoping with block syntax to ensure that the differently versioned
 regions remain lexically isolated.

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

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

 Of course, 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.

PPeerrffoorrmmaannccee EEnnhhaanncceemmeennttss • 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 the pthreads approach if the C11 approach is not available.

     _C_o_n_f_i_g_u_r_e 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.
     WWoorrssee - 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 _C_o_n_f_i_g_u_r_e 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 mmiigghhtt 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>.)

MMoodduulleess aanndd PPrraaggmmaattaa UUppddaatteedd MMoodduulleess aanndd PPrraaggmmaattaa • Archive::Tar has been upgraded from version 2.38 to 2.40.

 •   Attribute::Handlers has been upgraded from version 1.01 to 1.02.

 •   attributes has been upgraded from version 0.33 to 0.34.

 •   B has been upgraded from version 1.82 to 1.83.

 •   B::Concise has been upgraded from version 1.004 to 1.006.

 •   B::Deparse has been upgraded from version 1.56 to 1.64.

 •   bignum has been upgraded from version 0.51 to 0.65.

 •   charnames has been upgraded from version 1.48 to 1.50.

 •   Compress::Raw::Bzip2 has been upgraded from version 2.101 to 2.103.

 •   Compress::Raw::Zlib has been upgraded from version 2.101 to 2.105.

 •   CPAN has been upgraded from version 2.28 to 2.33.

 •   Data::Dumper has been upgraded from version 2.179 to 2.184.

 •   DB_File has been upgraded from version 1.855 to 1.857.

 •   Devel::Peek has been upgraded from version 1.30 to 1.32.

 •   Devel::PPPort has been upgraded from version 3.62 to 3.68.

 •   diagnostics has been upgraded from version 1.37 to 1.39.

 •   Digest has been upgraded from version 1.19 to 1.20.

 •   DynaLoader has been upgraded from version 1.50 to 1.52.

 •   Encode has been upgraded from version 3.08 to 3.17.

 •   Errno has been upgraded from version 1.33 to 1.36.

 •   experimental has been upgraded from version 0.024 to 0.028.

 •   Exporter has been upgraded from version 5.76 to 5.77.

 •   ExtUtils::MakeMaker has been upgraded from version 7.62 to 7.64.

 •   ExtUtils::Miniperl has been upgraded from version 1.10 to 1.11.

 •   ExtUtils::ParseXS has been upgraded from version 3.43 to 3.45.

 •   ExtUtils::Typemaps has been upgraded from version 3.43 to 3.45.

 •   Fcntl has been upgraded from version 1.14 to 1.15.

 •   feature has been upgraded from version 1.64 to 1.72.

 •   File::Compare has been upgraded from version 1.1006 to 1.1007.

 •   File::Copy has been upgraded from version 2.35 to 2.39.

 •   File::Fetch has been upgraded from version 1.00 to 1.04.

 •   File::Find has been upgraded from version 1.39 to 1.40.

 •   File::Glob has been upgraded from version 1.33 to 1.37.

 •   File::Spec has been upgraded from version 3.80 to 3.84.

 •   File::stat has been upgraded from version 1.09 to 1.12.

 •   FindBin has been upgraded from version 1.52 to 1.53.

 •   GDBM_File has been upgraded from version 1.19 to 1.23.

 •   Hash::Util has been upgraded from version 0.25 to 0.28.

 •   Hash::Util::FieldHash has been upgraded from version 1.21 to 1.26.

 •   HTTP::Tiny has been upgraded from version 0.076 to 0.080.

 •   I18N::Langinfo has been upgraded from version 0.19 to 0.21.

 •   if has been upgraded from version 0.0609 to 0.0610.

 •   IO has been upgraded from version 1.46 to 1.50.

 •   IO-Compress has been upgraded from version 2.102 to 2.106.

 •   IPC::Open3 has been upgraded from version 1.21 to 1.22.

 •   JSON::PP has been upgraded from version 4.06 to 4.07.

 •   libnet has been upgraded from version 3.13 to 3.14.

 •   Locale::Maketext has been upgraded from version 1.29 to 1.31.

 •   Math::BigInt has been upgraded from version 1.999818 to 1.999830.

 •   Math::BigInt::FastCalc has been upgraded from version 0.5009 to
     0.5012.

 •   Math::BigRat has been upgraded from version 0.2614 to 0.2621.

 •   Module::CoreList has been upgraded from version 5.20210520 to
     5.20220520.

 •   mro has been upgraded from version 1.25_001 to 1.26.

 •   NEXT has been upgraded from version 0.68 to 0.69.

 •   Opcode has been upgraded from version 1.50 to 1.57.

 •   open has been upgraded from version 1.12 to 1.13.

 •   overload has been upgraded from version 1.33 to 1.35.

 •   perlfaq has been upgraded from version 5.20210411 to 5.20210520.

 •   PerlIO has been upgraded from version 1.11 to 1.12.

 •   Pod::Functions has been upgraded from version 1.13 to 1.14.

 •   Pod::Html has been upgraded from version 1.27 to 1.33.

 •   Pod::Simple has been upgraded from version 3.42 to 3.43.

 •   POSIX has been upgraded from version 1.97 to 2.03.

 •   re has been upgraded from version 0.41 to 0.43.

 •   Scalar::Util has been upgraded from version 1.55 to 1.62.

 •   sigtrap has been upgraded from version 1.09 to 1.10.

 •   Socket has been upgraded from version 2.031 to 2.033.

 •   sort has been upgraded from version 2.04 to 2.05.

 •   Storable has been upgraded from version 3.23 to 3.26.

 •   Sys::Hostname has been upgraded from version 1.23 to 1.24.

 •   Test::Harness has been upgraded from version 3.43 to 3.44.

 •   Test::Simple has been upgraded from version 1.302183 to 1.302190.

 •   Text::ParseWords has been upgraded from version 3.30 to 3.31.

 •   Text::Tabs has been upgraded from version 2013.0523 to 2021.0814.

 •   Text::Wrap has been upgraded from version 2013.0523 to 2021.0814.

 •   threads has been upgraded from version 2.26 to 2.27.

 •   threads::shared has been upgraded from version 1.62 to 1.64.

 •   Tie::Handle has been upgraded from version 4.2 to 4.3.

 •   Tie::Hash has been upgraded from version 1.05 to 1.06.

 •   Tie::Scalar has been upgraded from version 1.05 to 1.06.

 •   Tie::SubstrHash has been upgraded from version 1.00 to 1.01.

 •   Time::HiRes has been upgraded from version 1.9767 to 1.9770.

 •   Unicode::Collate has been upgraded from version 1.29 to 1.31.

 •   Unicode::Normalize has been upgraded from version 1.28 to 1.31.

 •   Unicode::UCD has been upgraded from version 0.75 to 0.78.

 •   UNIVERSAL has been upgraded from version 1.13 to 1.14.

 •   version has been upgraded from version 0.9928 to 0.9929.

 •   VMS::Filespec has been upgraded from version 1.12 to 1.13.

 •   VMS::Stdio has been upgraded from version 2.45 to 2.46.

 •   warnings has been upgraded from version 1.51 to 1.58.

 •   Win32 has been upgraded from version 0.57 to 0.59.

 •   XS::APItest has been upgraded from version 1.16 to 1.22.

 •   XS::Typemap has been upgraded from version 0.18 to 0.19.

 •   XSLoader has been upgraded from version 0.30 to 0.31.

DDooccuummeennttaattiioonn NNeeww DDooccuummeennttaattiioonn _P_o_r_t_i_n_g_/_v_o_t_e___a_d_m_i_n___g_u_i_d_e_._p_o_d

 This document provides the process for administering an election or vote
 within the Perl Core Team.

CChhaannggeess ttoo EExxiissttiinngg DDooccuummeennttaattiioonn 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:

 _p_e_r_l_a_p_i

 •   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!

 _p_e_r_l_d_e_p_r_e_c_a_t_i_o_n

 •   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.

 _p_e_r_l_e_x_p_e_r_i_m_e_n_t

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

 _p_e_r_l_g_o_v

 •   The election process has been finetuned to allow the vote to be
     skipped if there are no more candidates than open seats.

 •   A special election is now allowed to be postponed for up to twelve
     weeks, for example until a normal election.

 _p_e_r_l_o_p

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

 _p_e_r_l_r_e

 •   Updated to discourage the use of the /d regexp modifier.

 _p_e_r_l_r_u_n

 •   --?? is now a synonym for --hh

 •   --gg is now a synonym for --00777777

DDiiaaggnnoossttiiccss 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.

NNeeww DDiiaaggnnoossttiiccss _N_e_w _E_r_r_o_r_s

 •   Can't "%s" out of a "defer" block

     (F) An attempt was made to jump out of the scope of a defer block by
     using a control-flow statement such as "return", "goto" or a loop
     control. This is not permitted.

 •   Can't modify %s in %s (for scalar assignment to "undef")

     Attempting to perform a scalar assignment to "undef", for example via
     "undef = $foo;", previously triggered a fatal runtime error with the
     message "Modification of a read-only value attempted."  It is more
     helpful to detect such attempted assignments prior to runtime, so
     they are now compile time errors, resulting in the message "Can't
     modify undef operator in scalar assignment".

 •   panic: newFORLOOP, %s

     The parser failed an internal consistency check while trying to parse
     a "foreach" loop.

 _N_e_w _W_a_r_n_i_n_g_s

 •   Built-in function '%s' is experimental

     A call is being made to a function in the "builtin::" namespace,
     which is currently experimental.

 •   defer is experimental

     The "defer" block modifier is experimental. If you want to use the
     feature, disable 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.

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

     This warning is emitted on a "use VERSION" statement that requests a
     version below v5.11 (when the effects of "use strict" would be
     disabled), after a previous declaration of one having a larger number
     (which would have enabled these effects)

 •   for my (...) is experimental

     This warning is emitted if you use "for" to iterate multiple values
     at a time. This syntax is currently experimental and its behaviour
     may change in future releases of Perl.

 •   Implicit use of @_ in %s with signatured subroutine is experimental

     An expression that implicitly involves the @_ arguments array was
     found in a subroutine that uses a signature.

 •   Use of @_ in %s with signatured subroutine is experimental

     An expression involving the @_ arguments array was found in a
     subroutine that uses a signature.

 •   Wide character in $0

     Attempts to put wide characters into the program name ($0) now
     provoke this warning.

CChhaannggeess ttoo EExxiissttiinngg DDiiaaggnnoossttiiccss • ‘/’ does not take a repeat count in %s

     This warning used to not include the "in %s".

 •   Subroutine %s redefined

     Localized subroutine redefinitions no longer trigger this warning.

 •   unexpected constant lvalue entersub entry via type/targ %d:%d" now
     has a panic prefix

     This makes it consistent with other checks of internal consistency
     when compiling a subroutine.

 •   Useless use of sort in scalar context is now in the new "scalar"
     category.

     When "sort" is used in scalar context, it provokes a warning that
     doing this is not useful. This warning used to be in the "void"
     category. A new category for warnings about scalar context has now
     been added, called "scalar".

 •   Removed a number of diagnostics

     Many diagnostics that have been removed from the perl core across
     many years have now _a_l_s_o been removed from the documentation.

CCoonnffiigguurraattiioonn aanndd CCoommppiillaattiioonn • 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

 •   _C_o_n_f_i_g_u_r_e 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 _x_l_o_c_a_l_e_._h is
     removed in a library update, or _x_l_o_c_a_l_e_._h isn't intended for public
     use. (github #18936 <https://github.com/Perl/perl5/pull/18936>)

TTeessttiinngg Tests were added and changed to reflect the other additions and changes in this release.

PPllaattffoorrmm SSuuppppoorrtt WWiinnddoowwss • Support for old MSVC++ (pre-VC12) has been removed

     These did not support C99 and hence can no longer be used to compile
     perl.

 •   Support for compiling perl on Windows using Microsoft Visual Studio
     2022 (containing Visual C++ 14.3) has been added.

 •   The :win32 IO layer has been removed. This experimental replacement
     for the :unix layer never reached maturity in its nearly two decades
     of existence.

VVMMSS #

 "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.

DDiissccoonnttiinnuueedd PPllaattffoorrmmss

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.

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.

 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.

     Unrelated changes accidentally broke the build for the NetWare port
     in September 2009, and in 12 years no-one has reported this.

PPllaattffoorrmm--SSppeecciiffiicc NNootteess 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.

IInntteerrnnaall CChhaannggeess • Since the removal of PERL_OBJECT in Perl 5.8, PERL_IMPLICIT_CONTEXT and MULTIPLICITY have been synonymous and they were being 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.

 •   The API constant formerly named "G_ARRAY", indicating list context,
     has now been renamed to a more accurate "G_LIST".  A compatibilty
     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 _p_e_r_l_._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 _e_m_b_e_d_._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.

 •   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.

 •   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 pphhaassee__nnaammee(()) 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)" _e_t_c (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 _m_i_g_h_t 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 wwrriitttteenn as an integer, but then rreeaadd
         as a string

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

     •   that same value that was initially wwrriitttteenn as a string, but then
         rreeaadd 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 _r_e_a_l_l_y 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.

     _T_h_e _e_x_i_s_t_i_n_g _g_u_e_s_s_w_o_r_k 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 nnoott affect any other diagnostic
     interfaces like "pv_display".

SSeelleecctteedd BBuugg FFiixxeess • uuttiimmee(()) now correctly sets errno/$! when called on a closed handle.

 •   The flags on the OPTVAL parameter to sseettssoocckkoopptt(()) 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 sseettssoocckkoopptt(()) 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

     1.  "tie" was called again on the same hash

     2.  The (now untied) hash was iterated (ie passed to any of "keys",
         "values" or "each")

     3.  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 immediatey followed by
     parens.

EErrrraattaa FFrroomm PPrreevviioouuss RReelleeaasseess • perl5300delta mistakenly identified a CVE whose correct identification is CVE-2015-1592.

OObbiittuuaarriieess 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 _B_a_d _M_o_v_i_e _N_i_g_h_t 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.

AAcckknnoowwlleeddggeemmeennttss Perl 5.36.0 represents approximately a year of development since Perl 5.34.0 and contains approximately 250,000 lines of changes across 2,000 files from 82 authors.

 Excluding auto-generated files, documentation and release tools, there
 were approximately 190,000 lines of changes to 1,300 .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 5.36.0:

 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.

 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.

RReeppoorrttiinngg BBuuggss 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 http://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.

GGiivvee TThhaannkkss 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.

SSEEEE AALLSSOO #

 The _C_h_a_n_g_e_s file for an explanation of how to view exhaustive details on
 what changed.

 The _I_N_S_T_A_L_L file for how to build Perl.

 The _R_E_A_D_M_E file for general stuff.

 The _A_r_t_i_s_t_i_c and _C_o_p_y_i_n_g files for copyright information.

perl v5.36.3 2023-07-08 PERL5360DELTA(1)