perl5271cdelta - what is new for cperl v5.27.1


This document describes the differences between the cperl 5.27.0 and the cperl 5.27.1 releases.

If you are upgrading from an earlier release such as v5.24.2c, first read the perl525*cdelta documentation, which describes differences between v5.25.1c and v5.26.0c

Core Enhancements

class, role, method, has

cperl has now classes, roles, methods and fields. Old user-subroutines or parser-hacks with these names are still supported, but not recommended. See perlclass.

Check and normalize stringified names

Before symbols and identifiers created from strings at run-time were added asis. Now those names are treated almost as in the parser at compile-time, i.e. unicode is normalized, mixed Unicode scripts are checked at run-time also. cperl-only.

Behaviour of "valid_ident" in perlapi:

    ${"\xc3\x28"}       => FALSE.  Illegal unicode, but no warning or error,
                           unless under strict names.
    ${"E\x{45}\x{301}"} => TRUE.   Normalized to $E\x{c9}
    ${"एxṰர::ʦፖㄡsȨ"}   => FALSE. Error: Invalid script Tamil in identifier
                            ர::ʦፖㄡsȨ for U+0BB0. Have Devanagari

See below "strict names". use strict fatalizes now any run-time identifier parsing problem.

strict names

strict names is the default when using use strict. Reject illegal identifiers at run-time when created dynamically from strings, which would be rejected at compile-time. cperl-only.

    use strict "names";
    ${"\$var"}    => Invalid identifier "$var" while "strict names"
    ${"\xff"}     => Invalid identifier "\377" while "strict names"
    ${"\xc3\x28"} => Invalid identifier "\303(" while "strict names"

See "Identifier parsing" in perldata and


Module removals

The following modules will be removed from the core distribution in a future release, and will at that time need to be installed from CPAN. Distributions on CPAN which require these modules will need to list them as prerequisites.

The core versions of these modules will now issue "deprecated"-category warnings to alert you to this fact. To silence these deprecation warnings, install the modules in question from CPAN.

Note that these are (with rare exceptions) fine modules that you are encouraged to continue to use. Their disinclusion from core primarily hinges on their necessity to bootstrapping a fully functional, CPAN-capable Perl installation, not usually on concerns over their design.


will be removed from core with 5.30, and needs to be installed from CPAN then. Best together with B::Flags.

Performance Enhancements

Modules and Pragmata

New Modules and Pragmata

Mu 0.01

For now only new and CREATE, implemented as XS builtins.


Just the documentation for the perl6 MOP.

Updated Modules and Pragmata

attributes 1.12c

Fixed :const parsing with SVs (cperl-only). Previously :const would set the containing sub to :const, now it sets the lexical to readonly, with deferring the attributes::import call after an assignment.

    my %h :const = (a => 1);
    assign %h = (...);
    attributes->import(PACKAGE, \%h, const);

See [cperl #294].

B 1.68_08

Add non-destructive $cv->PUREGV method, which does not create a GV from a CvNAMED $cv. Warning: $cv->GV does create a GV from a CvNAMED $cv.

Internal Refactor: thread API

Add many missing methods and docs. Some from B::C.

B::C 1.55_04

Protect from destructive $cv->GV, renamed is_lexsub to is_named, allow @0, &0, ... types.

B::Debug 1.25

Deprecated from CORE, will not be in 5.30 anymore. Avoid destructive CvNAMED vivification to GVs. Add cperl features.

base 2.26c

Turn off HvCLASS again, just turn on SvREADONLY @ISA. With all the new class features, we cannot and should not compete.

The problem is the new sub as :method warning with classes, which would cause all Test::Simple methods to be declared as :method, as they derive from base.

Cpanel::JSON::XS 3.0237

Stringify true again as "1". Disallow duplicate keys by default, only allow them in relaxed mode. De-fragilize t/96_mojo.t false test to "". It mostly is. Fix and unify utf8 handling with 5.6.2 and improve many utf8 tests. Add tests for boolean sv_yes and sv_no. Check for correct module in %INC. Relax inf/nan detection for newer msvcrt.dll runtime versions (it's now almost ANSI).

Devel::Peek 1.26_02

Add TYPECHECKED, RETTYPE and pad var names and types.

Devel::PPPort 3.36_02

Restore silence under make -s. I broke it in cperl 5.27.0

Add #if { CPERL && VERSION 5.26.0 }> support, support parser enum expectation.

deprecate 0.03_01

Add pod synopsis for modules for older perls.

Encode 2.92

Skip the flapping test t/Aliases.t on threaded smokers, with random segfaults. This is a long standing core bug, with PMOP aliases or clone. First observed at (since 5.6)

Stop directory tweaking $Encode::Encoding{utf8}

Fix gcc warnings for older gcc < 4.0

Where possible do not depend on value of $@, instead use return value of eval

Fix more XS problems in Encode.xs file

Load modules Encode::MIME::Name and Storable normally

Remove no warnings 'redefine'; and correctly loaddependences

Remove PP stubs and reformat predefine_encodings()

Run Encode XS BOOT code at compile time

Use Encode::define_encoding and propagate carp/croak message

cperl fixes: encoding undeprecated, no strict hashpairs

Cleanup code for handling fallback/replacement characters

ExtUtils::CBuilder 0.280226

Fix C++ compiler detection (RT #131749)

ExtUtils::Install 2.14

- Fix tests for when perl path contains a space

- Fix win32 check

- 'make -s' support: set $INSTALL_QUIET automatically

- Optimisations:

  * use our instead of vars
  * lazy load modules
  * make OS variables into constants
  * move some calculations out of a loop

- Removed instructions using Build.PL from README

- Load Win32API::File for _move_file_at_boot only when needed

- Allow disabling autosplit by omitting autosplit dir

ExtUtils::MakeMaker 8.30_04

Merge our fixes to upstream 7.30 (which has e.g. the dlltool mingw fixes). Many fixes were already in, but some new upstream bugs crept in.

Support IO::Scalar handle as $parsefile argument to ExtUtils::MM_Unix::parse_version().

fix Invalid Locale symbol name. Invalid identifier "ENCODING_UTF-8" while "strict names"

fix XSMULTI static with strict linkers, avoid duplicate symbol _boot_XS__Test in: Test.o blib/arch/auto/XS/Test/Test.a(Test.o)

xsstatic: fixup MAKE_APERL_FILE, which was Makefile.aperl.aperl

ExtUtils::ParseXS 3.35_02

Moved xs pods still missing from the CPAN release completely to core.

Bump versions.

fields 2.25c

A cperl class has now fields with @class::FIELDS targ offsets to the lexical fields, and the old %type::FIELDS hash pointing to the *class GV, allowing again compile-time type checks on typed object hash accesses.

File::Path 3.15_01c

Remove erroneous documentation. Correct skip count for Windows. Comment out two TODO tests. Make subdirectory names used in tests more random.

File::Spec::Functions 3.36_05

Bumped version from unparsable 3.3.65, which prevented e.g. File::chdir to install.

Filter::Simple 0.94

Various small documentation fixes. Swap out use for Remove use of deprecated \C regex feature. Filter::Simple was erroneously signalling eof if it encountered a ‘no MyFilter’ right after ‘use’: use MyFilter; no MyFilter; In this case it should simply not filter anything.

Getopt::Long 2.50

Fix bug

Fix bug Unfortunately, this withdraws a small part of fix 114999. GNU getopt_long() does not accept the (optional) argument to be passed to the option without = sign. We do, since not doing so breaks existing scripts.

Provide a default value for options (gnu_compat mode). Thanks to Andrew Gregory.


Bump versions of 3 Socket modules.

IPC::Cmd 0.98

Added wait_loop_callback for run_forked()

Only search in curdir in can_run() when on Win32 RT#105601

JSON::PP 2.94_01

Various, see

Locale::Codes 3.53

Fixed the default error condition in legacy modules.

Math::BigRat 0.2613

Fix problem with second operand being changed in multiplication (CPAN RT #121139).

Memoize 1.03

Skip flapping, timer-sensitive t/expmod_t.t tests on Travis CI.

Net::Ping 2.61

Fix ping_udp for a started udp echo server (PR#5 by Stephan Loyd)

Fix t/400_ping_syn.t phases

Try to handle Windows Socket::getnameinfo errors

Improve some tests on missing network connections

Opcode 1.39_02c

Added new 'oelem' and 'oelemfast' to :base_core

PathTools 4.68c

Add security usage note to File::Spec::no_upwards white space change so can compile under C++11 Protect modules also from . in @INC [perl #127384] (CVE-2016-1238)

Search::Dict 1.07_01

Bump version

SelectSaver 1.02_01

Bump version

Storable 3.05_13

mingw fix: use safe defaults, not segfaulting defaults. mingw fails on the stacksize binary search, leaving it empty.

strict 1.13c

Implemented strict 'names' to reject illegal identifiers created via no strict 'refs' also at run-time, not only at compile-time. See [cperl #282].

threads 2.16_01

Fix Clang macro backward compatibility per patch by Andy Grundman. Keep the old better doc. Keep our modglobal fix in global destruction from 2.12_01.

threads::shared 1.57

Fix Clang macro backward compatibility per patch by Andy Grundman. RT #131124 Memory allocation fix.

Time::HiRes 1.9744_01


add more potential clock constants, like CLOCK_MONOTONIC_FAST (available in FreeBSD), and not all potentially found clock constants were properly exported to be available from Perl, see your system's clock_gettime() documentation for the available ones

correct declared minimum Perl version (should be 5.6, was declared as 5.8 since 1.9727_03): blead af94b3ac

merged with our cperl test fixes. See

VMS::Studio 2.41_01

Bump version

Win32API::File 0.1204

Fix xsubpp warnings


New Documentation


Modern cperl classes and roles. The new syntax and features.

Changes to Existing Documentation

perlxs, perlxstut, perlxstypemap


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.

New Diagnostics

New Warnings

Changes to Existing Diagnostics

Configuration and Compilation

Utility Changes



Platform Support

Platform-Specific Notes


cperl on mingw was previously unsupported and didn't compile nor work.

The plan is to use mingw 32bit and 64bit packages instead of MSVC compiled packages, which do require a special MS runtime DLL.

Internal Changes

Selected Bug Fixes


cperl 5.27.1c represents approximately 3 months of development since cperl 5.27.0c and contains approximately 56,000 lines of changes across 570 files from 9 authors.

Excluding auto-generated files, documentation and release tools, there were approximately 26,000 lines of changes to 390 .pm, .t, .c and .h files.

The following people are known to have contributed the improvements that became cperl 5.27.1c:

Reini Urban, Tony Cook, vendethiel, François Perrad, Aaron Crane, David Mitchell, H.Merijn Brand, William N. Braswell, Jr.

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.

Generated with:

    cperl Porting/ cperl-5.27.0..HEAD

Reporting Bugs

If you find what you think is a bug, you might check the articles recently posted to the comp.lang.perl.misc newsgroup and the perl bug database at . There may also be information at , the Perl Home Page.

If you believe you have an unreported bug, please run the cperlbug program included with your release. Be sure to trim your bug down to a tiny but sufficient test case. Your bug report, along with the output of perl -V, will be sent off to to be analysed by the Perl porting team.

If you think it's a cperl specific bug or trust the cperl developers more please file an issue at

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


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.