PERL5101DELTA(1) Perl Programmers Reference Guide PERL5101DELTA(1)

PERL5101DELTA(1) Perl Programmers Reference Guide PERL5101DELTA(1) #

PERL5101DELTA(1) Perl Programmers Reference Guide PERL5101DELTA(1)

NNAAMMEE #

 perl5101delta - what is new for perl v5.10.1

DDEESSCCRRIIPPTTIIOONN #

 This document describes differences between the 5.10.0 release and the
 5.10.1 release.

 If you are upgrading from an earlier release such as 5.8.8, first read
 the perl5100delta, which describes differences between 5.8.8 and 5.10.0

IInnccoommppaattiibbllee CChhaannggeess SSwwiittcchh ssttaatteemmeenntt cchhaannggeess The handling of complex expressions by the “given”/“when” switch statement has been enhanced. There are two new cases where “when” now interprets its argument as a boolean, instead of an expression to be used in a smart match:

 flip-flop operators
     The ".." and "..." flip-flop operators are now evaluated in boolean
     context, following their usual semantics; see "Range Operators" in
     perlop.

     Note that, as in perl 5.10.0, "when (1..10)" will not work to test
     whether a given value is an integer between 1 and 10; you should use
     "when ([1..10])" instead (note the array reference).

     However, contrary to 5.10.0, evaluating the flip-flop operators in
     boolean context ensures it can now be useful in a "when()", notably
     for implementing bistable conditions, like in:

         when (/^=begin/ .. /^=end/) {
           # do something
         }

 defined-or operator
     A compound expression involving the defined-or operator, as in "when
     (expr1 // expr2)", will be treated as boolean if the first expression
     is boolean. (This just extends the existing rule that applies to the
     regular or operator, as in "when (expr1 || expr2)".)

 The next section details more changes brought to the semantics to the
 smart match operator, that naturally also modify the behaviour of the
 switch statements where smart matching is implicitly used.

SSmmaarrtt mmaattcchh cchhaannggeess _C_h_a_n_g_e_s _t_o _t_y_p_e_-_b_a_s_e_d _d_i_s_p_a_t_c_h

 The smart match operator "~~" is no longer commutative. The behaviour of
 a smart match now depends primarily on the type of its right hand
 argument. Moreover, its semantics have been adjusted for greater
 consistency or usefulness in several cases. While the general backwards
 compatibility is maintained, several changes must be noted:

 •   Code references with an empty prototype are no longer treated
     specially.  They are passed an argument like the other code
     references (even if they choose to ignore it).

 •   "%hash ~~ sub {}" and "@array ~~ sub {}" now test that the subroutine
     returns a true value for each key of the hash (or element of the
     array), instead of passing the whole hash or array as a reference to
     the subroutine.

 •   Due to the commutativity breakage, code references are no longer
     treated specially when appearing on the left of the "~~" operator,
     but like any vulgar scalar.

 •   "undef ~~ %hash" is always false (since "undef" can't be a key in a
     hash). No implicit conversion to "" is done (as was the case in perl
     5.10.0).

 •   "$scalar ~~ @array" now always distributes the smart match across the
     elements of the array. It's true if one element in @array verifies
     "$scalar ~~ $element". This is a generalization of the old behaviour
     that tested whether the array contained the scalar.

 The full dispatch table for the smart match operator is given in "Smart
 matching in detail" in perlsyn.

 _S_m_a_r_t _m_a_t_c_h _a_n_d _o_v_e_r_l_o_a_d_i_n_g

 According to the rule of dispatch based on the rightmost argument type,
 when an object overloading "~~" appears on the right side of the
 operator, the overload routine will always be called (with a 3rd argument
 set to a true value, see overload.) However, when the object will appear
 on the left, the overload routine will be called only when the rightmost
 argument is a simple scalar. This way distributivity of smart match
 across arrays is not broken, as well as the other behaviours with complex
 types (coderefs, hashes, regexes). Thus, writers of overloading routines
 for smart match mostly need to worry only with comparing against a
 scalar, and possibly with stringification overloading; the other common
 cases will be automatically handled consistently.

 "~~" will now refuse to work on objects that do not overload it (in order
 to avoid relying on the object's underlying structure). (However, if the
 object overloads the stringification or the numification operators, and
 if overload fallback is active, it will be used instead, as usual.)

OOtthheerr iinnccoommppaattiibbllee cchhaannggeess • The semantics of “use feature :5.10*” have changed slightly. See “Modules and Pragmata” for more information.

 •   It is now a run-time error to use the smart match operator "~~" with
     an object that has no overload defined for it. (This way "~~" will
     not break encapsulation by matching against the object's internal
     representation as a reference.)

 •   The version control system used for the development of the perl
     interpreter has been switched from Perforce to git.  This is mainly
     an internal issue that only affects people actively working on the
     perl core; but it may have minor external visibility, for example in
     some of details of the output of "perl -V". See perlrepository for
     more information.

 •   The internal structure of the "ext/" directory in the perl source has
     been reorganised. In general, a module "Foo::Bar" whose source was
     stored under _e_x_t_/_F_o_o_/_B_a_r_/ is now located under _e_x_t_/_F_o_o_-_B_a_r_/. Also,
     some modules have been moved from _l_i_b_/ to _e_x_t_/. This is purely a
     source tarball change, and should make no difference to the
     compilation or installation of perl, unless you have a very
     customised build process that explicitly relies on this structure, or
     which hard-codes the "nonxs_ext" _C_o_n_f_i_g_u_r_e parameter. Specifically,
     this change does not by default alter the location of any files in
     the final installation.

 •   As part of the "Test::Harness" 2.x to 3.x upgrade, the experimental
     "Test::Harness::Straps" module has been removed.  See "Updated
     Modules" for more details.

 •   As part of the "ExtUtils::MakeMaker" upgrade, the
     "ExtUtils::MakeMaker::bytes" and "ExtUtils::MakeMaker::vmsish"
     modules have been removed from this distribution.

 •   "Module::CoreList" no longer contains the %:patchlevel hash.

 •   This one is actually a change introduced in 5.10.0, but it was missed
     from that release's perldelta, so it is mentioned here instead.

     A bugfix related to the handling of the "/m" modifier and "qr"
     resulted in a change of behaviour between 5.8.x and 5.10.0:

         # matches in 5.8.x, doesn't match in 5.10.0
         $re = qr/^bar/; "foo\nbar" =~ /$re/m;

CCoorree EEnnhhaanncceemmeennttss UUnniiccooddee CChhaarraacctteerr DDaattaabbaassee 55..11..00 The copy of the Unicode Character Database included in Perl 5.10.1 has been updated to 5.1.0 from 5.0.0. See http://www.unicode.org/versions/Unicode5.1.0/#Notable_Changes for the notable changes.

AA pprrooppeerr iinntteerrffaaccee ffoorr pplluuggggaabbllee MMeetthhoodd RReessoolluuttiioonn OOrrddeerrss As of Perl 5.10.1 there is a new interface for plugging and using method resolution orders other than the default (linear depth first search). The C3 method resolution order added in 5.10.0 has been re-implemented as a plugin, without changing its Perl-space interface. See perlmroapi for more information.

TThhee “"oovveerrllooaaddiinngg"” pprraaggmmaa This pragma allows you to lexically disable or enable overloading for some or all operations. (Yuval Kogman)

PPaarraalllleell tteessttss The core distribution can now run its regression tests in parallel on Unix-like platforms. Instead of running “make test”, set “TEST_JOBS” in your environment to the number of tests to run in parallel, and run “make test_harness”. On a Bourne-like shell, this can be done as

     TEST_JOBS=3 make test_harness  # Run 3 tests in parallel

 An environment variable is used, rather than parallel make itself,
 because TAP::Harness needs to be able to schedule individual non-
 conflicting test scripts itself, and there is no standard interface to
 "make" utilities to interact with their job schedulers.

 Note that currently some test scripts may fail when run in parallel (most
 notably "ext/IO/t/io_dir.t"). If necessary run just the failing scripts
 again sequentially and see if the failures go away.

DDTTrraaccee ssuuppppoorrtt Some support for DTrace has been added. See “DTrace support” in _I_N_S_T_A_L_L.

SSuuppppoorrtt ffoorr “"ccoonnffiigguurree__rreeqquuiirreess"” iinn CCPPAANN mmoodduullee mmeettaaddaattaa Both “CPAN” and “CPANPLUS” now support the “configure_requires” keyword in the “META.yml” metadata file included in most recent CPAN distributions. This allows distribution authors to specify configuration prerequisites that must be installed before running _M_a_k_e_f_i_l_e_._P_L or _B_u_i_l_d_._P_L.

 See the documentation for "ExtUtils::MakeMaker" or "Module::Build" for
 more on how to specify "configure_requires" when creating a distribution
 for CPAN.

MMoodduulleess aanndd PPrraaggmmaattaa NNeeww MMoodduulleess aanndd PPrraaggmmaattaa “autodie” This is a new lexically-scoped alternative for the “Fatal” module. The bundled version is 2.06_01. Note that in this release, using a string eval when “autodie” is in effect can cause the autodie behaviour to leak into the surrounding scope. See “BUGS” in autodie for more details.

 "Compress::Raw::Bzip2"
     This has been added to the core (version 2.020).

 "parent"
     This pragma establishes an ISA relationship with base classes at
     compile time. It provides the key feature of "base" without the
     feature creep.

 "Parse::CPAN::Meta"
     This has been added to the core (version 1.39).

PPrraaggmmaattaa CChhaannggeess “attributes” Upgraded from version 0.08 to 0.09.

 "attrs"
     Upgraded from version 1.02 to 1.03.

 "base"
     Upgraded from version 2.13 to 2.14. See parent for a replacement.

 "bigint"
     Upgraded from version 0.22 to 0.23.

 "bignum"
     Upgraded from version 0.22 to 0.23.

 "bigrat"
     Upgraded from version 0.22 to 0.23.

 "charnames"
     Upgraded from version 1.06 to 1.07.

     The Unicode _N_a_m_e_A_l_i_a_s_e_s_._t_x_t database file has been added. This has
     the effect of adding some extra "\N" character names that formerly
     wouldn't have been recognised; for example, "\N{LATIN CAPITAL LETTER

GHA}". #

 "constant"
     Upgraded from version 1.13 to 1.17.

 "feature"
     The meaning of the ":5.10" and ":5.10.X" feature bundles has changed
     slightly. The last component, if any (i.e. "X") is simply ignored.
     This is predicated on the assumption that new features will not, in
     general, be added to maintenance releases. So ":5.10" and ":5.10.X"
     have identical effect. This is a change to the behaviour documented
     for 5.10.0.

 "fields"
     Upgraded from version 2.13 to 2.14 (this was just a version bump;
     there were no functional changes).

 "lib"
     Upgraded from version 0.5565 to 0.62.

 "open"
     Upgraded from version 1.06 to 1.07.

 "overload"
     Upgraded from version 1.06 to 1.07.

 "overloading"
     See "The "overloading" pragma" above.

 "version"
     Upgraded from version 0.74 to 0.77.

UUppddaatteedd MMoodduulleess “Archive::Extract” Upgraded from version 0.24 to 0.34.

 "Archive::Tar"
     Upgraded from version 1.38 to 1.52.

 "Attribute::Handlers"
     Upgraded from version 0.79 to 0.85.

 "AutoLoader"
     Upgraded from version 5.63 to 5.68.

 "AutoSplit"
     Upgraded from version 1.05 to 1.06.

 "B" Upgraded from version 1.17 to 1.22.

 "B::Debug"
     Upgraded from version 1.05 to 1.11.

 "B::Deparse"
     Upgraded from version 0.83 to 0.89.

 "B::Lint"
     Upgraded from version 1.09 to 1.11.

 "B::Xref"
     Upgraded from version 1.01 to 1.02.

 "Benchmark"
     Upgraded from version 1.10 to 1.11.

 "Carp"
     Upgraded from version 1.08 to 1.11.

“CGI” #

     Upgraded from version 3.29 to 3.43.  (also includes the
     "default_value for ppooppuupp__mmeennuu(())" fix from 3.45).

 "Compress::Zlib"
     Upgraded from version 2.008 to 2.020.

“CPAN” #

     Upgraded from version 1.9205 to 1.9402. "CPAN::FTP" has a local fix
     to stop it being too verbose on download failure.

“CPANPLUS” #

     Upgraded from version 0.84 to 0.88.

 "CPANPLUS::Dist::Build"
     Upgraded from version 0.06_02 to 0.36.

 "Cwd"
     Upgraded from version 3.25_01 to 3.30.

 "Data::Dumper"
     Upgraded from version 2.121_14 to 2.124.

“DB” #

     Upgraded from version 1.01 to 1.02.

 "DB_File"
     Upgraded from version 1.816_1 to 1.820.

 "Devel::PPPort"
     Upgraded from version 3.13 to 3.19.

 "Digest::MD5"
     Upgraded from version 2.36_01 to 2.39.

 "Digest::SHA"
     Upgraded from version 5.45 to 5.47.

 "DirHandle"
     Upgraded from version 1.01 to 1.03.

 "Dumpvalue"
     Upgraded from version 1.12 to 1.13.

 "DynaLoader"
     Upgraded from version 1.08 to 1.10.

 "Encode"
     Upgraded from version 2.23 to 2.35.

 "Errno"
     Upgraded from version 1.10 to 1.11.

 "Exporter"
     Upgraded from version 5.62 to 5.63.

 "ExtUtils::CBuilder"
     Upgraded from version 0.21 to 0.2602.

 "ExtUtils::Command"
     Upgraded from version 1.13 to 1.16.

 "ExtUtils::Constant"
     Upgraded from 0.20 to 0.22. (Note that neither of these versions are
     available on CPAN.)

 "ExtUtils::Embed"
     Upgraded from version 1.27 to 1.28.

 "ExtUtils::Install"
     Upgraded from version 1.44 to 1.54.

 "ExtUtils::MakeMaker"
     Upgraded from version 6.42 to 6.55_02.

     Note that "ExtUtils::MakeMaker::bytes" and
     "ExtUtils::MakeMaker::vmsish" have been removed from this
     distribution.

 "ExtUtils::Manifest"
     Upgraded from version 1.51_01 to 1.56.

 "ExtUtils::ParseXS"
     Upgraded from version 2.18_02 to 2.2002.

 "Fatal"
     Upgraded from version 1.05 to 2.06_01. See also the new pragma
     "autodie".

 "File::Basename"
     Upgraded from version 2.76 to 2.77.

 "File::Compare"
     Upgraded from version 1.1005 to 1.1006.

 "File::Copy"
     Upgraded from version 2.11 to 2.14.

 "File::Fetch"
     Upgraded from version 0.14 to 0.20.

 "File::Find"
     Upgraded from version 1.12 to 1.14.

 "File::Path"
     Upgraded from version 2.04 to 2.07_03.

 "File::Spec"
     Upgraded from version 3.2501 to 3.30.

 "File::stat"
     Upgraded from version 1.00 to 1.01.

 "File::Temp"
     Upgraded from version 0.18 to 0.22.

 "FileCache"
     Upgraded from version 1.07 to 1.08.

 "FileHandle"
     Upgraded from version 2.01 to 2.02.

 "Filter::Simple"
     Upgraded from version 0.82 to 0.84.

 "Filter::Util::Call"
     Upgraded from version 1.07 to 1.08.

 "FindBin"
     Upgraded from version 1.49 to 1.50.

 "GDBM_File"
     Upgraded from version 1.08 to 1.09.

 "Getopt::Long"
     Upgraded from version 2.37 to 2.38.

 "Hash::Util::FieldHash"
     Upgraded from version 1.03 to 1.04. This fixes a memory leak.

 "I18N::Collate"
     Upgraded from version 1.00 to 1.01.

“IO” #

     Upgraded from version 1.23_01 to 1.25.

     This makes non-blocking mode work on Windows in "IO::Socket::INET"

[CPAN #43573]. #

 "IO::Compress::*"
     Upgraded from version 2.008 to 2.020.

 "IO::Dir"
     Upgraded from version 1.06 to 1.07.

 "IO::Handle"
     Upgraded from version 1.27 to 1.28.

 "IO::Socket"
     Upgraded from version 1.30_01 to 1.31.

 "IO::Zlib"
     Upgraded from version 1.07 to 1.09.

 "IPC::Cmd"
     Upgraded from version 0.40_1 to 0.46.

 "IPC::Open3"
     Upgraded from version 1.02 to 1.04.

 "IPC::SysV"
     Upgraded from version 1.05 to 2.01.

 "lib"
     Upgraded from version 0.5565 to 0.62.

 "List::Util"
     Upgraded from version 1.19 to 1.21.

 "Locale::MakeText"
     Upgraded from version 1.12 to 1.13.

 "Log::Message"
     Upgraded from version 0.01 to 0.02.

 "Math::BigFloat"
     Upgraded from version 1.59 to 1.60.

 "Math::BigInt"
     Upgraded from version 1.88 to 1.89.

 "Math::BigInt::FastCalc"
     Upgraded from version 0.16 to 0.19.

 "Math::BigRat"
     Upgraded from version 0.21 to 0.22.

 "Math::Complex"
     Upgraded from version 1.37 to 1.56.

 "Math::Trig"
     Upgraded from version 1.04 to 1.20.

 "Memoize"
     Upgraded from version 1.01_02 to 1.01_03 (just a minor documentation
     change).

 "Module::Build"
     Upgraded from version 0.2808_01 to 0.34_02.

 "Module::CoreList"
     Upgraded from version 2.13 to 2.18. This release no longer contains
     the %Module::CoreList::patchlevel hash.

 "Module::Load"
     Upgraded from version 0.12 to 0.16.

 "Module::Load::Conditional"
     Upgraded from version 0.22 to 0.30.

 "Module::Loaded"
     Upgraded from version 0.01 to 0.02.

 "Module::Pluggable"
     Upgraded from version 3.6 to 3.9.

 "NDBM_File"
     Upgraded from version 1.07 to 1.08.

 "Net::Ping"
     Upgraded from version 2.33 to 2.36.

“NEXT” #

     Upgraded from version 0.60_01 to 0.64.

 "Object::Accessor"
     Upgraded from version 0.32 to 0.34.

“OS2::REXX” #

     Upgraded from version 1.03 to 1.04.

 "Package::Constants"
     Upgraded from version 0.01 to 0.02.

 "PerlIO"
     Upgraded from version 1.04 to 1.06.

 "PerlIO::via"
     Upgraded from version 0.04 to 0.07.

 "Pod::Man"
     Upgraded from version 2.16 to 2.22.

 "Pod::Parser"
     Upgraded from version 1.35 to 1.37.

 "Pod::Simple"
     Upgraded from version 3.05 to 3.07.

 "Pod::Text"
     Upgraded from version 3.08 to 3.13.

“POSIX” #

     Upgraded from version 1.13 to 1.17.

 "Safe"
     Upgraded from 2.12 to 2.18.

 "Scalar::Util"
     Upgraded from version 1.19 to 1.21.

 "SelectSaver"
     Upgraded from 1.01 to 1.02.

 "SelfLoader"
     Upgraded from 1.11 to 1.17.

 "Socket"
     Upgraded from 1.80 to 1.82.

 "Storable"
     Upgraded from 2.18 to 2.20.

 "Switch"
     Upgraded from version 2.13 to 2.14. Please see "Deprecations".

 "Symbol"
     Upgraded from version 1.06 to 1.07.

 "Sys::Syslog"
     Upgraded from version 0.22 to 0.27.

 "Term::ANSIColor"
     Upgraded from version 1.12 to 2.00.

 "Term::ReadLine"
     Upgraded from version 1.03 to 1.04.

 "Term::UI"
     Upgraded from version 0.18 to 0.20.

 "Test::Harness"
     Upgraded from version 2.64 to 3.17.

     Note that one side-effect of the 2.x to 3.x upgrade is that the
     experimental "Test::Harness::Straps" module (and its supporting
     "Assert", "Iterator", "Point" and "Results" modules) have been
     removed. If you still need this, then they are available in the
     (unmaintained) "Test-Harness-Straps" distribution on CPAN.

 "Test::Simple"
     Upgraded from version 0.72 to 0.92.

 "Text::ParseWords"
     Upgraded from version 3.26 to 3.27.

 "Text::Tabs"
     Upgraded from version 2007.1117 to 2009.0305.

 "Text::Wrap"
     Upgraded from version 2006.1117 to 2009.0305.

 "Thread::Queue"
     Upgraded from version 2.00 to 2.11.

 "Thread::Semaphore"
     Upgraded from version 2.01 to 2.09.

 "threads"
     Upgraded from version 1.67 to 1.72.

 "threads::shared"
     Upgraded from version 1.14 to 1.29.

 "Tie::RefHash"
     Upgraded from version 1.37 to 1.38.

 "Tie::StdHandle"
     This has documentation changes, and has been assigned a version for
     the first time: version 4.2.

 "Time::HiRes"
     Upgraded from version 1.9711 to 1.9719.

 "Time::Local"
     Upgraded from version 1.18 to 1.1901.

 "Time::Piece"
     Upgraded from version 1.12 to 1.15.

 "Unicode::Normalize"
     Upgraded from version 1.02 to 1.03.

 "Unicode::UCD"
     Upgraded from version 0.25 to 0.27.

     "charinfo()" now works on Unified CJK code points added to later
     versions of Unicode.

     "casefold()" has new fields returned to provide both a simpler
     interface and previously missing information. The old fields are
     retained for backwards compatibility. Information about Turkic-
     specific code points is now returned.

     The documentation has been corrected and expanded.

“UNIVERSAL” #

     Upgraded from version 1.04 to 1.05.

 "Win32"
     Upgraded from version 0.34 to 0.39.

 "Win32API::File"
     Upgraded from version 0.1001_01 to 0.1101.

 "XSLoader"
     Upgraded from version 0.08 to 0.10.

UUttiilliittyy CChhaannggeess _h_2_p_h Now looks in “include-fixed” too, which is a recent addition to gcc’s search path.

 _h_2_x_s
     No longer incorrectly treats enum values like macros (Daniel Burr).

     Now handles C++ style constants ("//") properly in enums. (A patch
     from Rainer Weikusat was used; Daniel Burr also proposed a similar
     fix).

 _p_e_r_l_5_d_b_._p_l
     "LVALUE" subroutines now work under the debugger.

     The debugger now correctly handles proxy constant subroutines, and
     subroutine stubs.

 _p_e_r_l_t_h_a_n_k_s
     Perl 5.10.1 adds a new utility _p_e_r_l_t_h_a_n_k_s, which is a variant of
     _p_e_r_l_b_u_g, but for sending non-bug-reports to the authors and
     maintainers of Perl. Getting nothing but bug reports can become a bit
     demoralising: we'll see if this changes things.

NNeeww DDooccuummeennttaattiioonn perlhaiku This contains instructions on how to build perl for the Haiku platform.

 perlmroapi
     This describes the new interface for pluggable Method Resolution
     Orders.

 perlperf
     This document, by Richard Foley, provides an introduction to the use
     of performance and optimization techniques which can be used with
     particular reference to perl programs.

 perlrepository
     This describes how to access the perl source using the _g_i_t version
     control system.

 perlthanks
     This describes the new _p_e_r_l_t_h_a_n_k_s utility.

CChhaannggeess ttoo EExxiissttiinngg DDooccuummeennttaattiioonn The various large “Changes*” files (which listed every change made to perl over the last 18 years) have been removed, and replaced by a small file, also called “Changes”, which just explains how that same information may be extracted from the git version control system.

 The file _P_o_r_t_i_n_g_/_p_a_t_c_h_i_n_g_._p_o_d has been deleted, as it mainly described
 interacting with the old Perforce-based repository, which is now
 obsolete.  Information still relevant has been moved to perlrepository.

 perlapi, perlintern, perlmodlib and perltoc are now all generated at
 build time, rather than being shipped as part of the release.

PPeerrffoorrmmaannccee EEnnhhaanncceemmeennttss • A new internal cache means that “isa()” will often be faster.

 •   Under "use locale", the locale-relevant information is now cached on
     read-only values, such as the list returned by "keys %hash". This
     makes operations such as "sort keys %hash" in the scope of "use
     locale" much faster.

 •   Empty "DESTROY" methods are no longer called.

IInnssttaallllaattiioonn aanndd CCoonnffiigguurraattiioonn IImmpprroovveemmeennttss _e_x_t_/ rreeoorrggaanniissaattiioonn The layout of directories in _e_x_t has been revised. Specifically, all extensions are now flat, and at the top level, with “/” in pathnames replaced by “-”, so that _e_x_t_/_D_a_t_a_/_D_u_m_p_e_r_/ is now _e_x_t_/_D_a_t_a_-_D_u_m_p_e_r_/, etc. The names of the extensions as specified to _C_o_n_f_i_g_u_r_e, and as reported by %Config::Config under the keys “dynamic_ext”, “known_extensions”, “nonxs_ext” and “static_ext” have not changed, and still use “/”. Hence this change will not have any affect once perl is installed. However, “Attribute::Handlers”, “Safe” and “mro” have now become extensions in their own right, so if you run _C_o_n_f_i_g_u_r_e with options to specify an exact list of extensions to build, you will need to change it to account for this.

 For 5.10.2, it is planned that many dual-life modules will have been
 moved from _l_i_b to _e_x_t; again this will have no effect on an installed
 perl, but will matter if you invoke _C_o_n_f_i_g_u_r_e with a pre-canned list of
 extensions to build.

CCoonnffiigguurraattiioonn iimmpprroovveemmeennttss If “vendorlib” and “vendorarch” are the same, then they are only added to @INC once.

 $Config{usedevel} and the C-level "PERL_USE_DEVEL" are now defined if
 perl is built with  "-Dusedevel".

 _C_o_n_f_i_g_u_r_e will enable use of "-fstack-protector", to provide protection
 against stack-smashing attacks, if the compiler supports it.

 _C_o_n_f_i_g_u_r_e will now determine the correct prototypes for re-entrant
 functions, and for "gconvert", if you are using a C++ compiler rather
 than a C compiler.

 On Unix, if you build from a tree containing a git repository, the
 configuration process will note the commit hash you have checked out, for
 display in the output of "perl -v" and "perl -V". Unpushed local commits
 are automatically added to the list of local patches displayed by "perl

-V". #

CCoommppiillaattiioonn iimmpprroovveemmeennttss As part of the flattening of _e_x_t, all extensions on all platforms are built by _m_a_k_e___e_x_t_._p_l. This replaces the Unix-specific _e_x_t_/_u_t_i_l_/_m_a_k_e___e_x_t, VMS-specific _m_a_k_e___e_x_t_._c_o_m and Win32-specific _w_i_n_3_2_/_b_u_i_l_d_e_x_t_._p_l.

PPllaattffoorrmm SSppeecciiffiicc CChhaannggeess AIX Removed _l_i_b_b_s_d for AIX 5L and 6.1. Only fflloocckk(()) was used from _l_i_b_b_s_d.

     Removed _l_i_b_g_d_b_m for AIX 5L and 6.1. The _l_i_b_g_d_b_m is delivered as an
     optional package with the AIX Toolbox. Unfortunately the 64 bit
     version is broken.

     Hints changes mean that AIX 4.2 should work again.

 Cygwin
     On Cygwin we now strip the last number from the DLL. This has been
     the behaviour in the cygwin.com build for years. The hints files have
     been updated.

 FreeBSD
     The hints files now identify the correct threading libraries on
     FreeBSD 7 and later.

 Irix
     We now work around a bizarre preprocessor bug in the Irix 6.5
     compiler: "cc -E -" unfortunately goes into K&R mode, but "cc -E
     file.c" doesn't.

 Haiku
     Patches from the Haiku maintainers have been merged in. Perl should
     now build on Haiku.

 MirOS BSD
     Perl should now build on MirOS BSD.

 NetBSD
     Hints now supports versions 5.*.

 Stratus VOS
     Various changes from Stratus have been merged in.

 Symbian
     There is now support for Symbian S60 3.2 SDK and S60 5.0 SDK.

 Win32
     Improved message window handling means that "alarm" and "kill"
     messages will no longer be dropped under race conditions.

 VMS Reads from the in-memory temporary files of "PerlIO::scalar" used to
     fail if $/ was set to a numeric reference (to indicate record-style
     reads).  This is now fixed.

     VMS now supports "getgrgid".

     Many improvements and cleanups have been made to the VMS file name
     handling and conversion code.

     Enabling the "PERL_VMS_POSIX_EXIT" logical name now encodes a POSIX
     exit status in a VMS condition value for better interaction with
     GNV's bash shell and other utilities that depend on POSIX exit
     values.  See "$?" in perlvms for details.

SSeelleecctteedd BBuugg FFiixxeess • 5.10.0 inadvertently disabled an optimisation, which caused a measurable performance drop in list assignment, such as is often used to assign function parameters from @_. The optimisation has been re- instated, and the performance regression fixed.

 •   Fixed memory leak on "while (1) { map 1, 1 }" [RT #53038].

 •   Some potential coredumps in PerlIO fixed [RT #57322,54828].

 •   The debugger now works with lvalue subroutines.

 •   The debugger's "m" command was broken on modules that defined
     constants [RT #61222].

 •   "crypt()" and string complement could return tainted values for
     untainted arguments [RT #59998].

 •   The "-i.suffix" command-line switch now recreates the file using
     restricted permissions, before changing its mode to match the
     original file. This eliminates a potential race condition [RT
     #60904].

 •   On some Unix systems, the value in $? would not have the top bit set
     ("$? & 128") even if the child core dumped.

 •   Under some circumstances, $^R could incorrectly become undefined [RT
     #57042].

 •   (XS) In various hash functions, passing a pre-computed hash to when
     the key is UTF-8 might result in an incorrect lookup.

 •   (XS) Including _X_S_U_B_._h before _p_e_r_l_._h gave a compile-time error [RT
     #57176].

 •   "$object->isa('Foo')" would report false if the package "Foo" didn't
     exist, even if the object's @ISA contained "Foo".

 •   Various bugs in the new-to 5.10.0 mro code, triggered by manipulating
     @ISA, have been found and fixed.

 •   Bitwise operations on references could crash the interpreter, e.g.
     "$x=\$y; $x |= "foo"" [RT #54956].

 •   Patterns including alternation might be sensitive to the internal
     UTF-8 representation, e.g.

         my $byte = chr(192);
         my $utf8 = chr(192); utf8::upgrade($utf8);
         $utf8 =~ /$byte|X}/i;       # failed in 5.10.0

 •   Within UTF8-encoded Perl source files (i.e. where "use utf8" is in
     effect), double-quoted literal strings could be corrupted where a
     "\xNN", "\0NNN" or "\N{}" is followed by a literal character with
     ordinal value greater than 255 [RT #59908].

 •   "B::Deparse" failed to correctly deparse various constructs:
     "readpipe STRING" [RT #62428], "CORE::require(STRING)" [RT #62488],
     "sub foo(_)" [RT #62484].

 •   Using "setpgrp()" with no arguments could corrupt the perl stack.

 •   The block form of "eval" is now specifically trappable by "Safe" and
     "ops".  Previously it was erroneously treated like string "eval".

 •   In 5.10.0, the two characters "[~" were sometimes parsed as the smart
     match operator ("~~") [RT #63854].

 •   In 5.10.0, the "*" quantifier in patterns was sometimes treated as
     "{0,32767}" [RT #60034, #60464]. For example, this match would fail:

         ("ab" x 32768) =~ /^(ab)*$/

 •   "shmget" was limited to a 32 bit segment size on a 64 bit OS [RT
     #63924].

 •   Using "next" or "last" to exit a "given" block no longer produces a
     spurious warning like the following:

         Exiting given via last at foo.pl line 123

 •   On Windows, '.\foo' and '..\foo'  were treated differently than
     './foo' and '../foo' by "do" and "require" [RT #63492].

 •   Assigning a format to a glob could corrupt the format; e.g.:

          *bar=*foo{FORMAT}; # foo format now bad

 •   Attempting to coerce a typeglob to a string or number could cause an
     assertion failure. The correct error message is now generated, "Can't
     coerce GLOB to _$_t_y_p_e".

 •   Under "use filetest 'access'", "-x" was using the wrong access mode.
     This has been fixed [RT #49003].

 •   "length" on a tied scalar that returned a Unicode value would not be
     correct the first time. This has been fixed.

 •   Using an array "tie" inside in array "tie" could SEGV. This has been
     fixed. [RT #51636]

 •   A race condition inside "PerlIOStdio_close()" has been identified and
     fixed. This used to cause various threading issues, including SEGVs.

 •   In "unpack", the use of "()" groups in scalar context was internally
     placing a list on the interpreter's stack, which manifested in
     various ways, including SEGVs.  This is now fixed [RT #50256].

 •   Magic was called twice in "substr", "\&$x", "tie $x, $m" and "chop".
     These have all been fixed.

 •   A 5.10.0 optimisation to clear the temporary stack within the
     implicit loop of "s///ge" has been reverted, as it turned out to be
     the cause of obscure bugs in seemingly unrelated parts of the
     interpreter [commit ef0d4e17921ee3de].

 •   The line numbers for warnings inside "elsif" are now correct.

 •   The ".." operator now works correctly with ranges whose ends are at
     or close to the values of the smallest and largest integers.

 •   "binmode STDIN, ':raw'" could lead to segmentation faults on some
     platforms.  This has been fixed [RT #54828].

 •   An off-by-one error meant that "index $str, ..." was effectively
     being executed as "index "$str\0", ...". This has been fixed [RT
     #53746].

 •   Various leaks associated with named captures in regexes have been
     fixed [RT #57024].

 •   A weak reference to a hash would leak. This was affecting "DBI" [RT
     #56908].

 •   Using (?|) in a regex could cause a segfault [RT #59734].

 •   Use of a UTF-8 "tr//" within a closure could cause a segfault [RT
     #61520].

 •   Calling "sv_chop()" or otherwise upgrading an SV could result in an
     unaligned 64-bit access on the SPARC architecture [RT #60574].

 •   In the 5.10.0 release, "inc_version_list" would incorrectly list
     "5.10.*" after "5.8.*"; this affected the @INC search order [RT
     #67628].

 •   In 5.10.0, "pack "a*", $tainted_value" returned a non-tainted value

[RT #52552]. #

 •   In 5.10.0, "printf" and "sprintf" could produce the fatal error
     "panic: utf8_mg_pos_cache_update" when printing UTF-8 strings [RT
     #62666].

 •   In the 5.10.0 release, a dynamically created "AUTOLOAD" method might
     be missed (method cache issue) [RT #60220,60232].

 •   In the 5.10.0 release, a combination of "use feature" and "//ee"
     could cause a memory leak [RT #63110].

 •   "-C" on the shebang ("#!") line is once more permitted if it is also
     specified on the command line. "-C" on the shebang line used to be a
     silent no-op _i_f it was not also on the command line, so perl 5.10.0
     disallowed it, which broke some scripts. Now perl checks whether it
     is also on the command line and only dies if it is not [RT #67880].

 •   In 5.10.0, certain types of re-entrant regular expression could
     crash, or cause the following assertion failure [RT #60508]:

         Assertion rx->sublen >= (s - rx->subbeg) + i failed

NNeeww oorr CChhaannggeedd DDiiaaggnnoossttiiccss “panic: sv_chop %s” This new fatal error occurs when the C routine “Perl_sv_chop()” was passed a position that is not within the scalar’s string buffer. This could be caused by buggy XS code, and at this point recovery is not possible.

 "Can't locate package %s for the parents of %s"
     This warning has been removed. In general, it only got produced in
     conjunction with other warnings, and removing it allowed an ISA
     lookup optimisation to be added.

 "v-string in use/require is non-portable"
     This warning has been removed.

 "Deep recursion on subroutine "%s""
     It is now possible to change the depth threshold for this warning
     from the default of 100, by recompiling the _p_e_r_l binary, setting the
     C pre-processor macro "PERL_SUB_DEPTH_WARN" to the desired value.

CChhaannggeedd IInntteerrnnaallss • The J.R.R. Tolkien quotes at the head of C source file have been checked and proper citations added, thanks to a patch from Tom Christiansen.

 •   "vcroak()" now accepts a null first argument. In addition, a full
     audit was made of the "not NULL" compiler annotations, and those for
     several other internal functions were corrected.

 •   New macros "dSAVEDERRNO", "dSAVE_ERRNO", "SAVE_ERRNO",
     "RESTORE_ERRNO" have been added to formalise the temporary saving of
     the "errno" variable.

 •   The function "Perl_sv_insert_flags" has been added to augment
     "Perl_sv_insert".

 •   The function "Perl_newSV_type(type)" has been added, equivalent to
     "Perl_newSV()" followed by "Perl_sv_upgrade(type)".

 •   The function "Perl_newSVpvn_flags()" has been added, equivalent to
     "Perl_newSVpvn()" and then performing the action relevant to the
     flag.

     Two flag bits are currently supported.

     "SVf_UTF8"
         This will call "SvUTF8_on()" for you. (Note that this does not
         convert an sequence of ISO 8859-1 characters to UTF-8). A
         wrapper, "newSVpvn_utf8()" is available for this.

     "SVs_TEMP"
         Call "sv_2mortal()" on the new SV.

     There is also a wrapper that takes constant strings,
     "newSVpvs_flags()".

 •   The function "Perl_croak_xs_usage" has been added as a wrapper to
     "Perl_croak".

 •   The functions "PerlIO_find_layer" and "PerlIO_list_alloc" are now
     exported.

 •   "PL_na" has been exterminated from the core code, replaced by local
     STRLEN temporaries, or "*_nolen()" calls. Either approach is faster
     than "PL_na", which is a pointer deference into the interpreter
     structure under ithreads, and a global variable otherwise.

 •   "Perl_mg_free()" used to leave freed memory accessible via SSvvMMAAGGIICC(())
     on the scalar. It now updates the linked list to remove each piece of
     magic as it is freed.

 •   Under ithreads, the regex in "PL_reg_curpm" is now reference counted.
     This eliminates a lot of hackish workarounds to cope with it not
     being reference counted.

 •   "Perl_mg_magical()" would sometimes incorrectly turn on
     "SvRMAGICAL()".  This has been fixed.

 •   The _p_u_b_l_i_c IV and NV flags are now not set if the string value has
     trailing "garbage". This behaviour is consistent with not setting the
     public IV or NV flags if the value is out of range for the type.

 •   SV allocation tracing has been added to the diagnostics enabled by
     "-Dm".  The tracing can alternatively output via the "PERL_MEM_LOG"
     mechanism, if that was enabled when the _p_e_r_l binary was compiled.

 •   Uses of "Nullav", "Nullcv", "Nullhv", "Nullop", "Nullsv" etc have
     been replaced by "NULL" in the core code, and non-dual-life modules,
     as "NULL" is clearer to those unfamiliar with the core code.

 •   A macro MUTABLE_PTR(p) has been added, which on (non-pedantic) gcc
     will not cast away "const", returning a "void *". Macros
     "MUTABLE_SV(av)", "MUTABLE_SV(cv)" etc build on this, casting to "AV
     *" etc without casting away "const". This allows proper compile-time
     auditing of "const" correctness in the core, and helped picked up
     some errors (now fixed).

 •   Macros "mPUSHs()" and "mXPUSHs()" have been added, for pushing SVs on
     the stack and mortalizing them.

 •   Use of the private structure "mro_meta" has changed slightly. Nothing
     outside the core should be accessing this directly anyway.

 •   A new tool, "Porting/expand-macro.pl" has been added, that allows you
     to view how a C preprocessor macro would be expanded when compiled.
     This is handy when trying to decode the macro hell that is the perl
     guts.

NNeeww TTeessttss Many modules updated from CPAN incorporate new tests.

 Several tests that have the potential to hang forever if they fail now
 incorporate a "watchdog" functionality that will kill them after a
 timeout, which helps ensure that "make test" and "make test_harness" run
 to completion automatically. (Jerry Hedden).

 Some core-specific tests have been added:

 t/comp/retainedlines.t
     Check that the debugger can retain source lines from "eval".

 t/io/perlio_fail.t
     Check that bad layers fail.

 t/io/perlio_leaks.t
     Check that PerlIO layers are not leaking.

 t/io/perlio_open.t
     Check that certain special forms of open work.

 t/io/perlio.t
     General PerlIO tests.

 t/io/pvbm.t
     Check that there is no unexpected interaction between the internal
     types "PVBM" and "PVGV".

 t/mro/package_aliases.t
     Check that mro works properly in the presence of aliased packages.

 t/op/dbm.t
     Tests for "dbmopen" and "dbmclose".

 t/op/index_thr.t
     Tests for the interaction of "index" and threads.

 t/op/pat_thr.t
     Tests for the interaction of esoteric patterns and threads.

 t/op/qr_gc.t
     Test that "qr" doesn't leak.

 t/op/reg_email_thr.t
     Tests for the interaction of regex recursion and threads.

 t/op/regexp_qr_embed_thr.t
     Tests for the interaction of patterns with embedded "qr//" and
     threads.

 t/op/regexp_unicode_prop.t
     Tests for Unicode properties in regular expressions.

 t/op/regexp_unicode_prop_thr.t
     Tests for the interaction of Unicode properties and threads.

 t/op/reg_nc_tie.t
     Test the tied methods of "Tie::Hash::NamedCapture".

 t/op/reg_posixcc.t
     Check that POSIX character classes behave consistently.

 t/op/re.t
     Check that exportable "re" functions in _u_n_i_v_e_r_s_a_l_._c work.

 t/op/setpgrpstack.t
     Check that "setpgrp" works.

 t/op/substr_thr.t
     Tests for the interaction of "substr" and threads.

 t/op/upgrade.t
     Check that upgrading and assigning scalars works.

 t/uni/lex_utf8.t
     Check that Unicode in the lexer works.

 t/uni/tie.t
     Check that Unicode and "tie" work.

KKnnoowwnn PPrroobblleemmss This is a list of some significant unfixed bugs, which are regressions from either 5.10.0 or 5.8.x.

 •   "List::Util::first" misbehaves in the presence of a lexical $_
     (typically introduced by "my $_" or implicitly by "given"). The
     variable which gets set for each iteration is the package variable
     $_, not the lexical $_ [RT #67694].

     A similar issue may occur in other modules that provide functions
     which take a block as their first argument, like

         foo { ... $_ ...} list

 •   The "charnames" pragma may generate a run-time error when a regex is
     interpolated [RT #56444]:

         use charnames ':full';
         my $r1 = qr/\N{THAI CHARACTER SARA I}/;
         "foo" =~ $r1;    # okay
         "foo" =~ /$r1+/; # runtime error

     A workaround is to generate the character outside of the regex:

         my $a = "\N{THAI CHARACTER SARA I}";
         my $r1 = qr/$a/;

 •   Some regexes may run much more slowly when run in a child thread
     compared with the thread the pattern was compiled into [RT #55600].

DDeepprreeccaattiioonnss The following items are now deprecated.

 •   "Switch" is buggy and should be avoided. From perl 5.11.0 onwards, it
     is intended that any use of the core version of this module will emit
     a warning, and that the module will eventually be removed from the
     core (probably in perl 5.14.0). See "Switch statements" in perlsyn
     for its replacement.

 •   "suidperl" will be removed in 5.12.0. This provides a mechanism to
     emulate setuid permission bits on systems that don't support it
     properly.

AAcckknnoowwlleeddggeemmeennttss Some of the work in this release was funded by a TPF grant.

 Nicholas Clark officially retired from maintenance pumpking duty at the
 end of 2008; however in reality he has put much effort in since then to
 help get 5.10.1 into a fit state to be released, including writing a
 considerable chunk of this perldelta.

 Steffen Mueller and David Golden in particular helped getting CPAN
 modules polished and synchronised with their in-core equivalents.

 Craig Berry was tireless in getting maint to run under VMS, no matter how
 many times we broke it for him.

 The other core committers contributed most of the changes, and applied
 most of the patches sent in by the hundreds of contributors listed in

_A_U_T_H_O_R_S. #

 (Sorry to all the people I haven't mentioned by name).

 Finally, thanks to Larry Wall, without whom none of this would be
 necessary.

RReeppoorrttiinngg BBuuggss 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 http://rt.perl.org/perlbug/ . 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 ppeerrllbbuugg 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 please
 send it to perl5-security-report@perl.org. This points to a closed
 subscription unarchived mailing list, which includes all the core
 committers, who will be able to help assess the impact of issues, figure
 out a resolution, and help co-ordinate the release of patches to mitigate
 or fix the problem across all platforms on which Perl is supported.
 Please only use this address for security issues in the Perl core, not
 for modules independently distributed on CPAN.

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 2019-02-13 PERL5101DELTA(1)