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PERLER SRI AYOUNG MARCC RSCHABER

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Abigail
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NAME

perldelta - what is new for perl v5.25.9

DESCRIPTION

This document describes differences between the 5.25.8 release and the 5.25.9 release.

If you are upgrading from an earlier release such as 5.25.7, first read perl5258delta, which describes differences between 5.25.7 and 5.25.8.

Core Enhancements

New regular expression modifier /xx

Specifying two x characters to modify a regular expression pattern does everything that a single one does, but additionally TAB and SPACE characters within a bracketed character class are generally ignored and can be added to improve readability, like /[ ^ A-Z d-f p-x ]/xx. Details are at "/x and /xx" in perlre.

Deprecations

String delimiters that aren't stand-alone graphemes are now deprecated

In order for Perl to eventually allow string delimiters to be Unicode grapheme clusters (which look like a single character, but may be a sequence of several ones), we have to stop allowing a single char delimiter that isn't a grapheme by itself. These are unlikely to exist in actual code, as they would typically display as attached to the character in front of them.

Performance Enhancements

  • A hash in boolean context is now sometimes faster, e.g.

        if (!%h) { ... }

    This was already special-cased, but some cases were missed, and even the ones which weren't have been improved.

  • Several other ops may now also be faster in boolean context.

Modules and Pragmata

Updated Modules and Pragmata

  • attributes has been upgraded from version 0.28 to 0.29.

    The deprecation message for the :unique and :locked attributes now mention they will disappear in Perl 5.28.

  • B::Deparse has been upgraded from version 1.39 to 1.40.

  • B::Xref has been upgraded from version 1.05 to 1.06.

    It now uses 3-arg open() instead of 2-arg open(). [perl #130122]

  • Compress::Raw::Bzip2 has been upgraded from version 2.069 to 2.070.

  • Compress::Raw::Zlib has been upgraded from version 2.069 to 2.070.

  • CPAN has been upgraded from version 2.14_01 to 2.16.

  • Data::Dumper was upgraded from version 2.166 to 2.167.

    This fixes a stack management bug. [perl #130487].

  • DB_File has been upgraded from version 1.838 to 1.840.

  • Devel::SelfStubber has been upgraded from version 1.05 to 1.06.

    It now uses 3-arg open() instead of 2-arg open(). [perl #130122]

  • diagnostics has been upgraded from version 1.35 to 1.36.

    It now uses 3-arg open() instead of 2-arg open(). [perl #130122]

  • DynaLoader has been upgraded from version 1.40 to 1.41.

  • Errno has been upgraded from version 1.27 to 1.28.

    It now uses 3-arg open() instead of 2-arg open(). [perl #130122]

  • ExtUtils::Embed has been upgraded from version 1.33 to 1.34.

    It now uses 3-arg open() instead of 2-arg open(). [perl #130122]

  • feature has been upgraded from version 1.45 to 1.46.

    Fixes the Unicode Bug in the range operator.

  • File::Glob has been upgraded from version 1.27 to 1.28.

    Issue a deprecation message for File::Glob::glob().

  • I18N::LangTags has been upgraded from version 0.41 to 0.42.

    It now uses 3-arg open() instead of 2-arg open(). [perl #130122]

  • lib has been upgraded from version 0.63 to 0.64.

    It now uses 3-arg open() instead of 2-arg open(). [perl #130122]

  • Module::CoreList has been upgraded from version 5.20161220 to 5.20170120.

  • OS2::Process has been upgraded from version 1.11 to 1.12.

    It now uses 3-arg open() instead of 2-arg open(). [perl #130122]

  • overload has been upgraded from version 1.27 to 1.28.

  • perl5db.pl has been upgraded from version 1.50 to 1.51.

    Ignore /dev/tty on non-Unix systems. [perl #113960]

  • PerlIO::scalar has been upgraded from version 0.25 to 0.26.

  • Pod::Html has been upgraded from version 1.2201 to 1.2202.

  • re has been upgraded from version 0.33 to 0.34

    This adds support for the new /xx regular expression pattern modifier, and a change to the use re 'strict' experimental feature. When re 'strict' is enabled, a warning now will be generated for all unescaped uses of the two characters } and ] in regular expression patterns (outside bracketed character classes) that are taken literally. This brings them more in line with the ) character which is always a metacharacter unless escaped. Being a metacharacter only sometimes, depending on action at a distance, can lead to silently having the pattern mean something quite different than was intended, which the re 'strict' mode is intended to minimize.

  • Storable has been upgraded from version 2.59 to 2.61.

    Fixes [perl #130098].

  • Symbol has been upgraded from version 1.07 to 1.08.

  • Term::ReadLine has been upgraded from version 1.15 to 1.16.

    It now uses 3-arg open() instead of 2-arg open(). [perl #130122]

  • Test has been upgraded from version 1.29 to 1.30.

    It now uses 3-arg open() instead of 2-arg open(). [perl #130122]

  • threads has been upgraded from version 2.10 to 2.12.

    Fixes [perl #130469].

  • threads::shared has been upgraded from version 1.52 to 1.54.

    This fixes [cpan #119529], [perl #130457]

  • Unicode::UCD has been upgraded from version 0.67 to 0.68.

    It now uses 3-arg open() instead of 2-arg open(). [perl #130122]

  • VMS::DCLsym has been upgraded from version 1.07 to 1.08.

    It now uses 3-arg open() instead of 2-arg open(). [perl #130122]

  • XSLoader has been upgraded from version 0.24 to 0.26.

    It now uses 3-arg open() instead of 2-arg open(). [perl #130122]

Documentation

New Documentation

perldeprecation

This file documents all upcoming deprecations, and some of the deprecations which already have been removed. The purpose of this documentation is two-fold: document what will disappear, and by which version, and serve as a guide for people dealing with code which has features that no longer work after an upgrade of their perl.

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.

New Diagnostics

New Warnings

Changes to Existing Diagnostics

As of Perl 5.25.9, all new deprecations will come with a version in which the feature will disappear. And with a few exceptions, most existing deprecations will state when they'll disappear. As such, most deprecation messages have changed.

  • Attribute "locked" is deprecated, and will disappear in Perl 5.28

  • Attribute "unique" is deprecated, and will disappear in Perl 5.28

  • "\c%c" is more clearly written simply as "%s". This will be a fatal error in Perl 5.28

  • Constants from lexical variables potentially modified elsewhere are deprecated. This will not be allowed in Perl 5.32

  • Deprecated use of my() in false conditional. This will be a fatal error in Perl 5.30

  • dump() better written as CORE::dump(). dump() will no longer be available in Perl 5.30

  • ${^ENCODING} is no longer supported. Its use will be fatal in Perl 5.28

  • File::Glob::glob() will disappear in perl 5.30. Use File::Glob::bsd_glob() instead.

  • %s() is deprecated on :utf8 handles. This will be a fatal error in Perl 5.30

  • $* is no longer supported. Its use will be fatal in Perl 5.30

  • $* is no longer supported. Its use will be fatal in Perl 5.30

  • Opening dirhandle %s also as a file. This will be a fatal error in Perl 5.28

  • Opening filehandle %s also as a directory. This will be a fatal error in Perl 5.28

  • Setting $/ to a reference to %s as a form of slurp is deprecated, treating as undef. This will be fatal in Perl 5.28

  • Unescaped left brace in regex is deprecated here (and will be fatal in Perl 5.30), passed through in regex; marked by <-- HERE in m/%s/

  • Unknown charname '' is deprecated. Its use will be fatal in Perl 5.28

  • Use of bare << to mean <<"" is deprecated. Its use will be fatal in Perl 5.28

  • Use of code point 0x%s is deprecated; the permissible max is 0x%s. This will be fatal in Perl 5.28

  • Use of comma-less variable list is deprecated. Its use will be fatal in Perl 5.28

  • Use of inherited AUTOLOAD for non-method %s() is deprecated. This will be fatal in Perl 5.28

  • Use of strings with code points over 0xFF as arguments to %s operator is deprecated. This will be a fatal error in Perl 5.28

Utility Changes

c2ph and pstruct

  • These old utilities have long since superceded by h2xs, and are now gone from the distribution.

Porting/sync-with-cpan

  • Many improvements

Configuration and Compilation

  • The dtrace build process has further changes:

    • If the -xnolibs is available, use that so a dtrace perl can be built within a FreeBSD jail.

    • On systems that build a dtrace object file (FreeBSD, Solaris and SystemTap's dtrace emulation), copy the input objects to a separate directory and process them there, and use those objects in the link, since dtrace -G also modifies these objects.

    • Add libelf to the build on FreeBSD 10.x, since dtrace adds references to libelf symbols.

    • Generate a dummy dtrace_main.o if dtrace -G fails to build it. A default build on Solaris generates probes from the unused inline functions, while they don't on FreeBSD, which causes dtrace -G to fail.

    [perl #130108]

  • You can now disable perl's use of the PERL_HASH_SEED and PERL_PERTURB_KEYS environment variables by configuring perl with -Accflags=NO_PERL_HASH_ENV.

  • You can now disable perl's use of the PERL_HASH_SEED_DEBUG environment variable by configuring perl with -Accflags=-DNO_PERL_HASH_SEED_DEBUG.

Internal Changes

  • New versions of macros like isALPHA_utf8 and toLOWER_utf8 have been added, each with the suffix _safe, like isSPACE_utf8_safe. These take an extra parameter, giving an upper limit of how far into the string it is safe to read. Using the old versions could cause attempts to read beyond the end of the input buffer if the UTF-8 is not well-formed, and their use now raises a deprecation warning. Details are at "Character classification" in perlapi.

  • Calling macros like isALPHA_utf8 on malformed UTF-8 have issued a deprecation warning since Perl v5.18. They now die. Similarly, macros like toLOWER_utf8 on malformed UTF-8 now die.

  • Calling the functions utf8n_to_uvchr and its derivatives, while passing a string length of 0 is now asserted against in DEBUGGING builds, and otherwise returns the Unicode REPLACEMENT CHARACTER. If you have nothing to decode, you shouldn't call the decode function.

  • The functions utf8n_to_uvchr and its derivatives now return the Unicode REPLACEMENT CHARACTER if called with UTF-8 that has the overlong malformation, and that malformation is allowed by the input parameters. This malformation is where the UTF-8 looks valid syntactically, but there is a shorter sequence that yields the same code point. This has been forbidden since Unicode version 3.1.

  • The functions utf8n_to_uvchr and its derivatives now accept an input flag to allow the overflow malformation. This malformation is when the UTF-8 may be syntactically valid, but the code point it represents is not capable of being represented in the word length on the platform. What "allowed" means in this case is that the function doesn't return an error, and advances the parse pointer to beyond the UTF-8 in question, but it returns the Unicode REPLACEMENT CHARACTER as the value of the code point (since the real value is not representable).

Selected Bug Fixes

  • Under use utf8, the entire Perl program is now checked that the UTF-8 is wellformed. This resolves [perl #126310].

  • The range operator .. on strings now handles its arguments correctly when in the scope of the unicode_strings feature. The previous behaviour was sufficiently unexpected that we believe no correct program could have made use of it.

  • The split operator did not ensure enough space was allocated for its return value in scalar context. It could then write a single pointer immediately beyond the end of the memory block allocated for the stack. [perl #130262]

  • Using a large code point with the W pack template character with the current output position aligned at just the right point could cause a write a single zero byte immediately beyond the end of an allocated buffer. [perl #129149]

  • Supplying the form picture argument as part of the form argument list where the picture specifies modifying the argument could cause an access to the new freed compiled form. [perl #129125]

  • Fix a problem with sort's build-in compare, where it would not sort correctly with 64-bit integers, and non-long doubles. [perl #130335]

  • Fix issues with /(?{ ... <<EOF })/ that broke Method-Signatures. [perl #130398]

  • Fix a macro which caused syntax error on an EBCDIC build.

  • Prevent tests from getting hung up on 'NonStop' option. [perl #130445]

  • Fixed an assertion failure with chop and chomp, which could be triggered by chop(@x =~ tr/1/1/). [perl #130198].

  • Fixed a comment skipping error under /x; it could stop skipping a byte early, which could be in the middle of a UTF-8 character. [perl #130495].

  • perldb now ignores /dev/tty on non-Unix systems. [perl #113960];

  • Fix assertion failure for {}->$x when $x isn't defined. [perl #130496].

  • DragonFly BSD now has support for setproctitle(). [perl #130068].

  • Fix an assertion error which could be triggered when lookahead string in patterns exceeded a minimum length. [perl #130522].

  • Only warn once per literal about a misplaced _. [perl #70878].

  • Ensure range-start is set after error in tr///. [perl #129342].

  • Don't read past start of string for unmatched backref; otherwise, we may have heap buffer overflow. [perl #129377].

  • Properly recognize mathematical digit ranges starting at U+1D7E. use re 'strict' is supposed to warn if you use a range whose start and end digit aren't from the same group of 10. It didn't do that for five groups of mathematical digits starting at U+1D7E.

Acknowledgements

Perl 5.25.9 represents approximately 4 weeks of development since Perl 5.25.8 and contains approximately 24,000 lines of changes across 400 files from 23 authors.

Excluding auto-generated files, documentation and release tools, there were approximately 17,000 lines of changes to 220 .pm, .t, .c and .h files.

Perl continues to flourish into its third decade thanks to a vibrant community of users and developers. The following people are known to have contributed the improvements that became Perl 5.25.9:

Aaron Crane, Abigail, Andreas König, Andy Lester, Aristotle Pagaltzis Chris 'BinGOs' Williams, Craig A. Berry, Dagfinn Ilmari Mannsåker, Dan Collins, David Mitchell, Father Chrysostomos, Hugo van der Sanden, James E Keenan, Jerry D. Hedden, John Lightsey, Karl Williamson, Paul Marquess, Peter Avalos, Sawyer X, Steve Hay, Tomasz Konojacki, Tony Cook, Zefram.

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://rt.perl.org/ . There may also be information at http://www.perl.org/ , the Perl Home Page.

If you believe you have an unreported bug, please run the perlbug 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 perlbug@perl.org to be analysed by the Perl porting team.

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.

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.