+=encoding utf8
+
=head1 NAME
perl5120delta - what is new for perl v5.12.0
-=head1 XXX - THIS DOCUMENT IS ONLY CURRENT THROUGH PERL5114
+=head1 DESCRIPTION
-FIX ME BEFORE RELEASE
+This document describes differences between the 5.10.0 release and the
+5.12.0 release.
-OTHER ISSUES:
+Many of the bug fixes in 5.12.0 are already included in the 5.10.1
+maintenance release.
-UPDATED MODULE LIST NEEDS TO BE GENERATED
-ORDERING NEEDS CHECKING
-HEAVY COPYEDITING IS NEEDED
+You can see the list of those changes in the 5.10.1 release notes
+(L<perl5101delta>).
-=head1 DESCRIPTION
+=head1 Core Enhancements
-This document describes differences between the 5.10.0 release and
-the 5.12.0 release.
+=head2 New C<package NAME VERSION> syntax
-Many of the bug fixes in 5.12.0 were already seen in the 5.10.1
-maintenance release since the two releases were kept closely
-coordinated (while 5.12.0 was still called 5.11.something).
+This new syntax allows a module author to set the $VERSION of a namespace
+when the namespace is declared with 'package'. It eliminates the need
+for C<our $VERSION = ...> and similar constructs. E.g.
-You can see the list of changes in the 5.10.1 release
-by reading L<perl5101delta>.
+ package Foo::Bar 1.23;
+ # $Foo::Bar::VERSION == 1.23
-=head1 Core Enhancements
+There are several advantages to this:
+
+=over
+
+=item *
+
+C<$VERSION> is parsed in exactly the same way as C<use NAME VERSION>
+
+=item *
+
+C<$VERSION> is set at compile time
+
+=item *
+
+C<$VERSION> is a version object that provides proper overloading of
+comparison operators so comparing C<$VERSION> to decimal (1.23) or
+dotted-decimal (v1.2.3) version numbers works correctly.
+
+=item *
+
+Eliminates C<$VERSION = ...> and C<eval $VERSION> clutter
+
+=item *
+
+As it requires VERSION to be a numeric literal or v-string
+literal, it can be statically parsed by toolchain modules
+without C<eval> the way MM-E<gt>parse_version does for C<$VERSION = ...>
+
+=back
+
+It does not break old code with only C<package NAME>, but code that uses
+C<package NAME VERSION> will need to be restricted to perl 5.12.0 or newer
+This is analogous to the change to C<open> from two-args to three-args.
+Users requiring the latest Perl will benefit, and perhaps after several
+years, it will become a standard practice.
+
+
+However, C<package NAME VERSION> requires a new, 'strict' version
+number format. See L<"Version number formats"> for details.
+
+
+=head2 The C<...> operator
+
+A new operator, C<...>, nicknamed the Yada Yada operator, has been added.
+It is intended to mark placeholder code that is not yet implemented.
+See L<perlop/"Yada Yada Operator">.
+
+=head2 Implicit strictures
+
+Using the C<use VERSION> syntax with a version number greater or equal
+to 5.11.0 will lexically enable strictures just like C<use strict>
+would do (in addition to enabling features.) The following:
+
+ use 5.12.0;
+
+means:
+
+ use strict;
+ use feature ':5.12';
+
+=head2 Unicode improvements
+
+Perl 5.12 comes with Unicode 5.2, the latest version available to
+us at the time of release. This version of Unicode was released in
+October 2009. See L<http://www.unicode.org/versions/Unicode5.2.0> for
+further details about what's changed in this version of the standard.
+See L<perlunicode> for instructions on installing and using other versions
+of Unicode.
+
+Additionally, Perl's developers have significantly improved Perl's Unicode
+implementation. For full details, see L</Unicode overhaul> below.
+
+=head2 Y2038 compliance
+
+Perl's core time-related functions are now Y2038 compliant. (It may not mean much to you, but your kids will love it!)
=head2 qr overloading
new kinds of keyword-headed expression and compound statement. The
syntax following the keyword is defined entirely by the extension. This
allow a completely non-Perl sublanguage to be parsed inline, with the
-correct ops cleanly generated. This feature is currently considered
-experimental.
+correct ops cleanly generated.
See L<perlapi/PL_keyword_plugin> for the mechanism. The Perl core
source distribution also includes a new module
purposes, and is not normally installed, but also serves as an example
of how to use the new mechanism.
+Perl's developers consider this feature to be experimental. We may remove
+it or change it in a backwards-incompatible way in Perl 5.14.
+
=head2 APIs for more internals
The lowest layers of the lexer and parts of the pad system now have C
areas. It is intended that the Perl 5.13 development cycle will see the
addition of a full range of clean, supported interfaces.
+Perl's developers consider this feature to be experimental. We may remove
+it or change it in a backwards-incompatible way in Perl 5.14.
+
=head2 Overridable function lookup
Where an extension module hooks the creation of rv2cv ops to modify the
mechanism, so extensions could only properly influence subroutine names
that appeared with an C<&> sigil.)
-=head2 Unicode version
-
-Perl is shipped with the latest Unicode version, 5.2, dated October 2009. See
-L<http://www.unicode.org/versions/Unicode5.2.0> for details about this release
-of Unicode. See L<perlunicode> for instructions on installing and using
-older versions of Unicode.
-
-=head2 Unicode properties
-
-Perl can now handle every Unicode character property. A new pod,
-L<perluniprops>, lists all available non-Unihan character properties. By
-default the Unihan properties and certain others (deprecated and Unicode
-internal-only ones) are not exposed. See below for more details on
-these; there is also a section in the pod listing them, and explaining
-why they are not exposed.
-
-Perl now fully supports the Unicode compound-style of using C<=> and C<:>
-in writing regular expressions: C<\p{property=value}> and
-C<\p{property:value}> (both of which mean the same thing).
-
-Perl now fully supports the Unicode loose matching rules for text
-between the braces in C<\p{...}> constructs. In addition, Perl allows
-underscores between digits of numbers.
-
-All the Unicode-defined synonyms for properties and property values are
-now accepted.
-
-C<qr/\X/>, which matches a Unicode logical character, has been expanded to work
-better with various Asian languages. It now is defined as an C<extended
-grapheme cluster>. (See L<http://www.unicode.org/reports/tr29/>).
-Anything matched previously and that made sense will continue to be
-matched, but in addition:
-
-=over
-
-=item *
-
-C<\X> will now not break apart a C<S<CR LF>> sequence.
-
-=item *
-
-C<\X> will now match a sequence including the C<ZWJ> and C<ZWNJ> characters.
-
-=item *
-
-C<\X> will now always match at least one character, including an initial mark.
-Marks generally come after a base character, but it is possible in Unicode to
-have them in isolation, and C<\X> will now handle that case, for example at the
-beginning of a line or after a C<ZWSP>. And this is the part where C<\X>
-doesn't match the things that it used to that don't make sense. Formerly, for
-example, you could have the nonsensical case of an accented LF.
-
-=item *
-
-C<\X> will now match a (Korean) Hangul syllable sequence, and the Thai and Lao
-exception cases.
-
-=back
-
-Otherwise, this change should be transparent for the non-affected languages.
-
-C<\p{...}> matches using the Canonical_Combining_Class property were
-completely broken in previous Perls. This is now fixed.
-
-In previous Perls, the Unicode C<Decomposition_Type=Compat> property and a
-Perl extension had the same name, which led to neither matching all the
-correct values (with more than 100 mistakes in one, and several thousand
-in the other). The Perl extension has now been renamed to be
-C<Decomposition_Type=Noncanonical> (short: C<dt=noncanon>). It has the same
-meaning as was previously intended, namely the union of all the
-non-canonical Decomposition types, with Unicode C<Compat> being just one of
-those.
-
-C<\p{Uppercase}> and C<\p{Lowercase}> have been brought into line with the
-Unicode definitions. This means they each match a few more characters
-than previously.
-
-C<\p{Cntrl}> now matches the same characters as C<\p{Control}>. This means it
-no longer will match Private Use (gc=co), Surrogates (gc=cs), nor Format
-(gc=cf) code points. The Format code points represent the biggest
-possible problem. All but 36 of them are either officially deprecated
-or strongly discouraged from being used. Of those 36, likely the most
-widely used are the soft hyphen (U+00AD), and BOM, ZWSP, ZWNJ, WJ, and
-similar, plus bidirectional controls.
-
-C<\p{Alpha}> now matches the same characters as C<\p{Alphabetic}>. The Perl
-definition included a number of things that aren't really alpha (all
-marks), while omitting many that were. As a direct consequence, the
-definitions of C<\p{Alnum}> and C<\p{Word}> which depend on Alpha also change.
-
-C<\p{Word}> also now doesn't match certain characters it wasn't supposed
-to, such as fractions.
-
-C<\p{Print}> no longer matches the line control characters: Tab, LF, CR,
-FF, VT, and NEL. This brings it in line with the documentation.
-
-C<\p{Decomposition_Type=Canonical}> now includes the Hangul syllables.
-
-The Numeric type property has been extended to include the Unihan
-characters.
-
-There is a new Perl extension, the 'Present_In', or simply 'In',
-property. This is an extension of the Unicode Age property, but
-C<\p{In=5.0}> matches any code point whose usage has been determined
-I<as of> Unicode version 5.0. The C<\p{Age=5.0}> only matches code points
-added in I<precisely> version 5.0.
-
-A number of properties did not have the correct values for unassigned
-code points. This is now fixed. The affected properties are
-Bidi_Class, East_Asian_Width, Joining_Type, Decomposition_Type,
-Hangul_Syllable_Type, Numeric_Type, and Line_Break.
-
-The Default_Ignorable_Code_Point, ID_Continue, and ID_Start properties
-have been updated to their current Unicode definitions.
-
-Certain properties that are supposed to be Unicode internal-only were
-erroneously exposed by previous Perls. Use of these in regular
-expressions will now generate, if enabled, a deprecated warning message.
-The properties are: Other_Alphabetic, Other_Default_Ignorable_Code_Point,
-Other_Grapheme_Extend, Other_ID_Continue, Other_ID_Start, Other_Lowercase,
-Other_Math, and Other_Uppercase.
-
-An installation can now fairly easily change which Unicode properties
-Perl understands. As mentioned above, certain properties are by default
-turned off. These include all the Unihan properties (which should be
-accessible via the CPAN module Unicode::Unihan) and any deprecated or
-Unicode internal-only property that Perl has never exposed.
-
-The generated files in the C<lib/unicore/To> directory are now more
-clearly marked as being stable, directly usable by applications.
-New hash entries in them give the format of the normal entries,
-which allows for easier machine parsing. Perl can generate files
-in this directory for any property, though most are suppressed. An
-installation can choose to change which get written. Instructions
-are in L<perluniprops>.
-
-=head2 Regular Expressions
-
-U+0FFFF is now a legal character in regular expressions.
-
-=head2 Unicode properties
-
-C<\p{XDigit}> now matches the same characters as C<\p{Hex_Digit}>. This
-means that in addition to the characters it currently matches,
-C<[A-Fa-f0-9]>, it will also match their fullwidth equivalent forms, for
-example U+FF10: FULLWIDTH DIGIT ZERO.
-
-=head2 Unicode Character Database 5.1.0
-
-The copy of the Unicode Character Database included in Perl 5.11.0 has
-been updated to 5.1.0 from 5.0.0. See
-L<http://www.unicode.org/versions/Unicode5.1.0/#Notable_Changes> for the
-notable changes.
-
=head2 A proper interface for pluggable Method Resolution Orders
-As of Perl 5.11.0 there is a new interface for plugging and using method
-resolution orders other than the default (linear depth first search).
+As of Perl 5.12.0 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 L<perlmroapi> for
more information.
-=head2 The C<overloading> pragma
-
-This pragma allows you to lexically disable or enable overloading
-for some or all operations. (Yuval Kogman)
-
-=head2 C<\N> regex escape
-
-A new regex escape has been added, C<\N>. It will match any character that
-is not a newline, independently from the presence or absence of the single
-line match modifier C</s>. (If C<\N> is followed by an opening brace and
-by a letter, perl will still assume that a Unicode character name is
-coming, so compatibility is preserved.) (Rafael Garcia-Suarez)
-
-=head2 Implicit strictures
-
-Using the C<use VERSION> syntax with a version number greater or equal
-to 5.11.0 will also lexically enable strictures just like C<use strict>
-would do (in addition to enabling features.) So, the following:
-
- use 5.11.0;
-
-will now imply:
-
- use strict;
- use feature ':5.11';
-
-=head2 Parallel tests
-The core distribution can now run its regression tests in parallel on
-Unix-like platforms. Instead of running C<make test>, set C<TEST_JOBS> in
-your environment to the number of tests to run in parallel, and run
-C<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
-L<TAP::Harness> needs to be able to schedule individual non-conflicting test
-scripts itself, and there is no standard interface to C<make> utilities to
-interact with their job schedulers.
+=head2 C<\N> experimental regex escape
-Note that currently some test scripts may fail when run in parallel (most
-notably C<ext/IO/t/io_dir.t>). If necessary run just the failing scripts
-again sequentially and see if the failures go away.
+Perl now supports C<\N>, a new regex escape which you can think of as
+the inverse of C<\n>. It will match any character that is not a newline,
+independently from the presence or absence of the single line match
+modifier C</s>. It is not usable within a character class. C<\N{3}>
+means to match 3 non-newlines; C<\N{5,}> means to match at least 5.
+C<\N{NAME}> still means the character or sequence named C<NAME>, but
+C<NAME> no longer can be things like C<3>, or C<5,>.
-=head2 The C<...> operator
+This will break a L<custom charnames translator|charnames/CUSTOM
+TRANSLATORS> which allows numbers for character names, as C<\N{3}> will
+now mean to match 3 non-newline characters, and not the character whose
+name is C<3>. (No name defined by the Unicode standard is a number,
+so only custom translators might be affected.)
-A new operator, C<...>, nicknamed the Yada Yada operator, has been added.
-It is intended to mark placeholder code that is not yet implemented.
-See L<perlop/"Yada Yada Operator">. (chromatic)
+Perl's developers are somewhat concerned about possible user confusion
+with the existing C<\N{...}> construct which matches characters by their
+Unicode name. Consequently, this feature is experimental. We may remove
+it or change it in a backwards-incompatible way in Perl 5.14.
=head2 DTrace support
-Some support for DTrace has been added. See "DTrace support" in F<INSTALL>.
+Perl now has some support for DTrace. See "DTrace support" in F<INSTALL>.
=head2 Support for C<configure_requires> in CPAN module metadata
-Both C<CPAN> and C<CPANPLUS> now support the C<configure_requires> keyword
-in the F<META.yml> metadata file included in most recent CPAN distributions.
-This allows distribution authors to specify configuration prerequisites that
-must be installed before running F<Makefile.PL> or F<Build.PL>.
+Both C<CPAN> and C<CPANPLUS> now support the C<configure_requires>
+keyword in the F<META.yml> metadata file included in most recent CPAN
+distributions. This allows distribution authors to specify configuration
+prerequisites that must be installed before running F<Makefile.PL>
+or F<Build.PL>.
-See the documentation for C<ExtUtils::MakeMaker> or C<Module::Build> for more
-on how to specify C<configure_requires> when creating a distribution for CPAN.
+See the documentation for C<ExtUtils::MakeMaker> or C<Module::Build> for
+more on how to specify C<configure_requires> when creating a distribution
+for CPAN.
=head2 C<each> is now more flexible
The C<each> function can now operate on arrays.
-=head2 Y2038 compliance
+=head2 C<when> as a statement modifier
-Perl's core time-related functions are now Y2038 compliant. (With 29
-years to spare!)
+C<when> is now allowed to be used as a statement modifier.
=head2 C<$,> flexibility
The variable C<$,> may now be tied.
-=head2 // in where clauses
+=head2 // in when clauses
// now behaves like || in when clauses
terminated by nul byte, but with the length passed to the socket()
system call.
-=head2 Add C<package NAME VERSION> syntax
-
-This new syntax allows a module author to set the $VERSION of a namespace
-when the namespace is declared with 'package'. It eliminates the need
-for C<our $VERSION = ...> and similar constructs. E.g.
-
- package Foo::Bar 1.23;
- # $Foo::Bar::VERSION == 1.23
-
-There are several advantages to this:
-
-=over
-
-=item *
-
-C<$VERSION> is parsed in I<exactly> the same way as C<use NAME VERSION>
-
-=item *
-
-C<$VERSION> is set at compile time
-
-=item *
-
-Eliminates C<$VERSION = ...> and C<eval $VERSION> clutter
-
-=item *
-
-As it requires VERSION to be a numeric literal or v-string
-literal, it can be statically parsed by toolchain modules
-without C<eval> the way MM-E<gt>parse_version does for C<$VERSION = ...>
+=head2 32-bit limit on substr arguments removed
-=item *
+The 32-bit limit on C<substr> arguments has now been removed. The full
+range of the system's signed and unsigned integers is now available for
+the C<pos> and C<len> arguments.
-Alpha versions with underscores do not need to be quoted; static
-parsing will preserve the underscore, but during compilation, Perl
-will remove underscores as it does for all numeric literals
+=head1 Potentially Incompatible Changes
-It does not break old code with only C<package NAME>, but code that uses
-C<package NAME VERSION> will need to be restricted to perl 5.11.X or newer
-This is analogous to the change to C<open> from two-args to three-args.
-Users requiring the latest Perl will benefit, and perhaps N years from
-now it will become standard practice when Perl 5.12 is targeted the way
-that 5.6 is today.
+=head2 Deprecations warn by default
-=back
+Over the years, Perl's developers have deprecated a number of language
+features for a variety of reasons. Perl now defaults to issuing a
+warning if a deprecated language feature is used. Many of the deprecations
+Perl now warns you about have been deprecated for many years. You can
+find a list of what was deprecated in a given release of Perl in the
+C<perl5xxdelta.pod> file for that release.
-=head1 Incompatible Changes
+To disable this feature in a given lexical scope, you should use C<no
+warnings 'deprecated';> For information about which language features
+are deprecated and explanations of various deprecation warnings, please
+see L<perldiag.pod>. See L</Deprecations> below for the list of features
+and modules Perl's developers have deprecated as part of this release.
=head2 Version number formats
Acceptable version number formats have been formalized into "strict" and
-"lax" rules. C<package NAME VERSION> takes a strict version number. C<use
-NAME VERSION> takes a lax version number. C<UNIVERSAL::VERSION> and the
-L<version> object constructors take lax version numbers. Providing an
-invalid version will result in a fatal error.
-
-These formats will be documented fully in the L<version> module in a
-subsequent release of Perl 5.11. To a first approximation, a "strict"
-version number is a positive decimal number (integer or decimal-fraction)
-without exponentiation or else a dotted-decimal v-string with a leading 'v'
-character and at least three components. A "lax" version number allows
-v-strings with fewer than three components or without a leading 'v'. Under
-"lax" rules, both decimal and dotted-decimal versions may have a trailing
-"alpha" component separated by an underscore character after a fractional
-or dotted-decimal component.
+"lax" rules. C<package NAME VERSION> takes a strict version number.
+C<UNIVERSAL::VERSION> and the L<version> object constructors take lax
+version numbers. Providing an invalid version will result in a fatal
+error. The version argument in C<use NAME VERSION> is first parsed as a
+numeric literal or v-string and then passed to C<UNIVERSAL::VERSION>
+(and must then pass the "lax" format test).
+
+These formats are documented fully in the L<version> module. To a first
+approximation, a "strict" version number is a positive decimal number
+(integer or decimal-fraction) without exponentiation or else a
+dotted-decimal v-string with a leading 'v' character and at least three
+components. A "lax" version number allows v-strings with fewer than
+three components or without a leading 'v'. Under "lax" rules, both
+decimal and dotted-decimal versions may have a trailing "alpha"
+component separated by an underscore character after a fractional or
+dotted-decimal component.
The L<version> module adds C<version::is_strict> and C<version::is_lax>
functions to check a scalar against these rules.
-=head2 Unicode interpretation of \w, \d, \s, and the POSIX character classes redefined.
-
-Previous versions of Perl tried to map POSIX style character class
-definitions onto Unicode property names so that patterns would "do what
-you meant" when matches were made against latin-1 or unicode strings.
-This proved to be a mistake, breaking character class negation, causing
-forward compatibility problems (as Unicode keeps updating their property
-definitions and adding new characters), and other problems.
-
-Therefore we have now defined a new set of artificial "unicode" property
-names which will be used to do unicode matching of patterns using POSIX
-style character classes and perl short-form escape character classes
-like \w and \d.
-
-The key change here is that \d will no longer match every digit in the
-unicode standard (there are thousands) nor will \w match every word
-character in the standard, instead they will match precisely their POSIX
-or Perl definition.
-
-Those needing to match based on Unicode properties can continue to do so
-by using the \p{} syntax to match whichever property they like,
-including the new artificial definitions.
-
-B<NOTE:> This is a backwards incompatible no-warning change in
-behaviour. If you are upgrading and you process large volumes of text
-look for POSIX and Perl style character classes and change them to the
-relevent property name (by removing the word 'Posix' from the current
-name).
-
-The following table maps the POSIX character class names, the escapes
-and the old and new Unicode property mappings:
-
- POSIX Esc Class New-Property ! Old-Property
- ----------------------------------------------+-------------
- alnum [0-9A-Za-z] IsPosixAlnum ! IsAlnum
- alpha [A-Za-z] IsPosixAlpha ! IsAlpha
- ascii [\000-\177] IsASCII = IsASCII
- blank [\011 ] IsPosixBlank !
- cntrl [\0-\37\177] IsPosixCntrl ! IsCntrl
- digit \d [0-9] IsPosixDigit ! IsDigit
- graph [!-~] IsPosixGraph ! IsGraph
- lower [a-z] IsPosixLower ! IsLower
- print [ -~] IsPosixPrint ! IsPrint
- punct [!-/:-@[-`{-~] IsPosixPunct ! IsPunct
- space [\11-\15 ] IsPosixSpace ! IsSpace
- \s [\11\12\14\15 ] IsPerlSpace ! IsSpacePerl
- upper [A-Z] IsPosixUpper ! IsUpper
- word \w [0-9A-Z_a-z] IsPerlWord ! IsWord
- xdigit [0-9A-Fa-f] IsXDigit = IsXDigit
-
-If you wish to build perl with the old mapping you may do so by setting
-
- #define PERL_LEGACY_UNICODE_CHARCLASS_MAPPINGS 1
-
-in regcomp.h, and then setting
-
- PERL_TEST_LEGACY_POSIX_CC
-
-to true your enviornment when testing.
-
=head2 @INC reorganization
-In @INC, ARCHLIB and PRIVLIB now occur after after the current version's
-site_perl and vendor_perl.
+In C<@INC>, C<ARCHLIB> and C<PRIVLIB> now occur after after the current
+version's C<site_perl> and C<vendor_perl>. Modules installed into
+C<site_perl> and C<vendor_perl> will now be loaded in preference to
+those installed in C<ARCHLIB> and C<PRIVLIB>.
+
+
+=head2 REGEXPs are now first class
+
+Internally, Perl now treates compiled regular expressions (such as
+those created with C<qr//>) as first class entities. Perl modules which
+serialize, deserialize or otherwise have deep interaction with Perl's
+internal data structures need to be updated for this change. Affected
+modules include L<FreezeThaw>,L<Data::Dump::Streamer> and L<Regexp::Copy>.
+
=head2 Switch statement changes
-The handling of complex expressions by the C<given>/C<when> switch
-statement has been enhanced. These enhancements are also available in
-5.10.1 and subsequent 5.10 releases. There are two new cases where
+The C<given>/C<when> switch statement handles complex statements better
+than Perl 5.10.0 did (These enhancements are also available in
+5.10.1 and subsequent 5.10 releases.) There are two new cases where
C<when> now interprets its argument as a boolean, instead of an
expression to be used in a smart match:
-=head2 flip-flop operators
+=over
+
+=item flip-flop operators
The C<..> and C<...> flip-flop operators are now evaluated in boolean
context, following their usual semantics; see L<perlop/"Range Operators">.
whether a given value is an integer between 1 and 10; you should use
C<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 C<when()>, notably for
-implementing bistable conditions, like in:
+However, contrary to 5.10.0, evaluating the flip-flop operators in
+boolean context ensures it can now be useful in a C<when()>, notably
+for implementing bistable conditions, like in:
when (/^=begin/ .. /^=end/) {
# do something
}
-=head2 defined-or operator
+=item defined-or operator
A compound expression involving the defined-or operator, as in
C<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 C<when (expr1 || expr2)>.)
+=back
+
=head2 Smart match changes
-This section details more changes brought to the semantics to
-the smart match operator, that naturally also modify the behaviour
+Since Perl 5.10.0, Perl's developers have made a number of changes to
+the smart match operator. These, of course, also alter the behaviour
of the switch statements where smart matching is implicitly used.
These changes were also made for the 5.10.1 release, and will remain in
subsequent 5.10 releases.
object overloads the stringification or the numification operators, and
if overload fallback is active, it will be used instead, as usual.)
-=head2 Labels can't be keywords
-
-Labels used as targets for the C<goto>, C<last>, C<next> or C<redo>
-statements cannot be keywords anymore. This restriction will prevent
-potential confusion between the C<goto LABEL> and C<goto EXPR> syntaxes:
-for example, a statement like C<goto print> would jump to a label whose
-name would be the return value of C<print()>, (usually 1), instead of a
-label named C<print>. Moreover, the other control flow statements
-would just ignore any keyword passed to them as a label name. Since
-such labels cannot be defined anymore, this kind of error will be
-avoided.
-
-=head2 Other incompatible changes
+=head2 Other potentially incompatible changes
=over 4
=item *
-The boolkeys op moved to the group of hash ops. This breaks binary
-compatibility.
+The definitions of a number of Unicode properties have changed to match
+those of the current Unicode standard. These are listed above under
+L</Unicode overhaul>. This change may break code that expects the old
+definitions.
=item *
-C<\s> C<\w> and C<\d> once again have the semantics they had in Perl 5.8.x.
+The boolkeys op has moved to the group of hash ops. This breaks binary
+compatibility.
=item *
-Filehandles are blessed directly into C<IO::Handle>, as C<FileHandle> is
-merely a wrapper around C<IO::Handle>.
+Filehandles are now always blessed into C<IO::File>.
The previous behaviour was to bless Filehandles into L<FileHandle>
(an empty proxy class) if it was loaded into memory and otherwise
=item *
-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 C<perl -V>. See L<perlrepository> for more information.
-
-=item *
-
-The internal structure of the C<ext/> directory in the perl source has
-been reorganised. In general, a module C<Foo::Bar> whose source was
-stored under F<ext/Foo/Bar/> is now located under F<ext/Foo-Bar/>. Also,
-nearly all dual-life modules have been moved from F<lib/> to F<ext/>. 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
-C<nonxs_ext> F<Configure> parameter. Specifically, this change does not by
-default alter the location of any files in the final installation.
+Perl's developers now use git, rather than Perforce. This should be
+a purely internal change only relevant to people actively working on
+the core. However, you may see minor difference in perl as a consequence
+of the change. For example in some of details of the output of C<perl
+-V>. See L<perlrepository> for more information.
=item *
As part of the C<Test::Harness> 2.x to 3.x upgrade, the experimental
C<Test::Harness::Straps> module has been removed.
-See L</"Updated Modules"> for more details.
+See L</"Modules and Pragmata"> for more details.
=item *
C<Module::CoreList> no longer contains the C<%:patchlevel> hash.
-=item *
-
-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 C</m> modifier and C<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;
=item *
UTF-8 support in the regexp engine.
This allows a build to complete with PERL_UNICODE set and a UTF-8 locale.
-Without this there's a bootstrapping problem, as miniperl can't load the UTF-8
-components of the regexp engine, because they're not yet built.
+Without this there's a bootstrapping problem, as miniperl can't load
+the UTF-8 components of the regexp engine, because they're not yet built.
=item *
=item *
-Tied filehandles now have an additional method EOF which provides the EOF type
+Tied filehandles now have an additional method EOF which provides the
+EOF type.
=item *
To better match all other flow control statements, C<foreach> may no
longer be used as an attribute.
+=item *
+
+Perl's command-line switch "-P", which was deprecated in version 5.10.0, has
+now been removed.
+
=back
+
=head1 Deprecations
From time to time, Perl's developers find it necessary to deprecate
holding back other features or causing performance problems. Sometimes,
the reasons are more complex. Wherever possible, we try to keep deprecated
functionality available to developers in its previous form for at least
-one major release. So long as a deprecated feature isn't actively
+one major release. So long as a deprecated feature isn't actively
disrupting our ability to maintain and extend Perl, we'll try to leave
it in place as long as possible.
-The following items are now deprecated.
+The following items are now deprecated:
+
+=over
+
+=item suidperl
+
+C<suidperl> is no longer part of Perl. It used to provide a mechanism to
+emulate setuid permission bits on systems that don't support it properly.
+
+
+=item Use of C<:=> to mean an empty attribute list
+
+An accident of Perl's parser meant that these constructions were all
+equivalent:
+
+ my $pi := 4;
+ my $pi : = 4;
+ my $pi : = 4;
+
+with the C<:> being treated as the start of an attribute list, which
+ends before the C<=>. As whitespace is not significant here, all are
+parsed as an empty attribute list, hence all the above are equivalent
+to, and better written as
+
+ my $pi = 4;
+
+because no attribute processing is done for an empty list.
+
+As is, this meant that C<:=> cannot be used as a new token, without
+silently changing the meaning of existing code. Hence that particular
+form is now deprecated, and will become a syntax error. If it is
+absolutely necessary to have empty attribute lists (for example,
+because of a code generator) then avoid the warning by adding a space
+before the C<=>.
+
+=item C<< UNIVERSAL->import() >>
+
+The method C<< UNIVERSAL->import() >> is now deprecated. Attempting to
+pass import arguments to a C<use UNIVERSAL> statement will result in a
+deprecation warning.
+
+
+=item Use of "goto" to jump into a construct
+
+Using C<goto> to jump from an outer scope into an inner scope is now
+deprecated. This rare use case was causing problems in the
+implementation of scopes.
+
+=item Custom character names in \N{name} that don't look like names
+
+In C<\N{I<name>}>, I<name> can be just about anything. The standard
+Unicode names have a very limited domain, but a custom name translator
+could create names that are, for example, made up entirely of punctuation
+symbols. It is now deprecated to make names that don't begin with an
+alphabetic character, and aren't alphanumeric or contain other than
+a very few other characters, namely spaces, dashes, parentheses
+and colons. Because of the added meaning of C<\N> (See L</C<\N>
+experimental regex escape>), names that look like curly brace -enclosed
+quantifiers won't work. For example, C<\N{3,4}> now means to match 3 to
+4 non-newlines; before a custom name C<3,4> could have been created.
+
+=item Deprecated Modules
+
+The following modules will be removed from the core distribution in a
+future release, and should be installed from CPAN instead. Distributions
+on CPAN which require these should add them to their prerequisites. The
+core versions of these modules warnings will issue a deprecation warning.
+
+If you ship a packaged version of Perl, either alone or as part of a
+larger system, then you should carefully consider the reprecussions of
+core module deprecations. You may want to consider shipping your default
+build of Perl with packages for some or all deprecated modules which
+install into C<vendor> or C<site> perl library directories. This will
+inhibit the deprecation warnings.
+
+Alternatively, you may want to consider patching F<lib/deprecate.pm>
+to provide deprecation warnings specific to your packaging system
+or distribution of Perl, consistent with how your packaging system
+or distribution manages a staged transition from a release where the
+installation of a single package provides the given functionality, to
+a later release where the system administrator needs to know to install
+multiple packages to get that same functionality.
+
+You can silence these deprecation warnings by installing the modules
+in question from CPAN. To install the latest version of all of them,
+just install C<Task::Deprecations::5_12>.
+
+=over
+
+=item L<Class::ISA>
+
+=item L<Pod::Plainer>
+
+=item L<Shell>
+
+=item L<Switch>
+
+Switch is buggy and should be avoided. You may find Perl's new
+C<given>/C<when> feature a suitable replacement. See L<perlsyn/"Switch
+statements"> for more information.
+
+=back
+
+=item Assignment to $[
+
+=item Use of the attribute :locked on subroutines
+
+=item Use of "locked" with the attributes pragma
+
+=item Use of "unique" with the attributes pragma
+
+=item Perl_pmflag
+
+C<Perl_pmflag> is no longer part of Perl's public API. Calling it now
+generates a deprecation warning, and it will be removed in a future
+release. Although listed as part of the API, it was never documented,
+and only ever used in F<toke.c>, and prior to 5.10, F<regcomp.c>. In
+core, it has been replaced by a static function.
+
+=item Numerous Perl 4-era libraries
+
+F<termcap.pl>, F<tainted.pl>, F<stat.pl>, F<shellwords.pl>, F<pwd.pl>,
+F<open3.pl>, F<open2.pl>, F<newgetopt.pl>, F<look.pl>, F<find.pl>,
+F<finddepth.pl>, F<importenv.pl>, F<hostname.pl>, F<getopts.pl>,
+F<getopt.pl>, F<getcwd.pl>, F<flush.pl>, F<fastcwd.pl>, F<exceptions.pl>,
+F<ctime.pl>, F<complete.pl>, F<cacheout.pl>, F<bigrat.pl>, F<bigint.pl>,
+F<bigfloat.pl>, F<assert.pl>, F<abbrev.pl>, F<dotsh.pl>, and
+F<timelocal.pl> are all now deprecated. Using them will incur a warning.
+
+
+=back
+
+=head1 Unicode overhaul
+
+Perl's developers have made a concerted effort to update Perl to be in
+sync with the latest Unicode standard. Changes for this include:
+
+Perl can now handle every Unicode character property. New documentation,
+L<perluniprops>, lists all available non-Unihan character properties. By
+default, perl does not expose Unihan, deprecated or Unicode-internal
+properties. See below for more details on these; there is also a section
+in the pod listing them, and explaining why they are not exposed.
+
+Perl now fully supports the Unicode compound-style of using C<=>
+and C<:> in writing regular expressions: C<\p{property=value}> and
+C<\p{property:value}> (both of which mean the same thing).
+
+Perl now fully supports the Unicode loose matching rules for text between
+the braces in C<\p{...}> constructs. In addition, Perl allows underscores
+between digits of numbers.
+
+Perl now accepts all the Unicode-defined synonyms for properties and
+property values.
+
+C<qr/\X/>, which matches a Unicode logical character, has
+been expanded to work better with various Asian languages. It
+now is defined as an I<extended grapheme cluster>. (See
+L<http://www.unicode.org/reports/tr29/>). Anything matched previously
+and that made sense will continue to be accepted. Additionally:
+
+=over
+
+=item *
+
+C<\X> will not break apart a C<S<CR LF>> sequence.
+
+=item *
+
+C<\X> will now match a sequence which includes the C<ZWJ> and C<ZWNJ>
+characters.
+
+=item *
+
+C<\X> will now always match at least one character, including an initial
+mark. Marks generally come after a base character, but it is possible in
+Unicode to have them in isolation, and C<\X> will now handle that case,
+for example at the beginning of a line, or after a C<ZWSP>. And this is
+the part where C<\X> doesn't match the things that it used to that don't
+make sense. Formerly, for example, you could have the nonsensical case
+of an accented LF.
+
+=item *
+
+C<\X> will now match a (Korean) Hangul syllable sequence, and the Thai
+and Lao exception cases.
+
+=back
+
+Otherwise, this change should be transparent for the non-affected
+languages.
+
+C<\p{...}> matches using the Canonical_Combining_Class property were
+completely broken in previous releases of Perl. They should now work
+correctly.
+
+Before Perl 5.12, the Unicode C<Decomposition_Type=Compat> property
+and a Perl extension had the same name, which led to neither matching
+all the correct values (with more than 100 mistakes in one, and several
+thousand in the other). The Perl extension has now been renamed to be
+C<Decomposition_Type=Noncanonical> (short: C<dt=noncanon>). It has the
+same meaning as was previously intended, namely the union of all the
+non-canonical Decomposition types, with Unicode C<Compat> being just
+one of those.
+
+C<\p{Decomposition_Type=Canonical}> now includes the Hangul syllables.
+
+C<\p{Uppercase}> and C<\p{Lowercase}> now work as the Unicode standard
+says they should. This means they each match a few more characters than
+they used to.
+
+C<\p{Cntrl}> now matches the same characters as C<\p{Control}>. This
+means it no longer will match Private Use (gc=co), Surrogates (gc=cs),
+nor Format (gc=cf) code points. The Format code points represent the
+biggest possible problem. All but 36 of them are either officially
+deprecated or strongly discouraged from being used. Of those 36, likely
+the most widely used are the soft hyphen (U+00AD), and BOM, ZWSP, ZWNJ,
+WJ, and similar characters, plus bidirectional controls.
+
+C<\p{Alpha}> now matches the same characters as C<\p{Alphabetic}>. Before
+5.12, Perl's definition definition included a number of things that aren't
+really alpha (all marks) while omitting many that were. The definitions
+of C<\p{Alnum}> and C<\p{Word}> depend on Alpha's definition and have
+changed accordingly.
+
+C<\p{Word}> no longer incorrectly matches non-word characters such
+as fractions.
+
+C<\p{Print}> no longer matches the line control characters: Tab, LF,
+CR, FF, VT, and NEL. This brings it in line with standards and the
+documentation.
+
+C<\p{XDigit}> now matches the same characters as C<\p{Hex_Digit}>. This
+means that in addition to the characters it currently matches,
+C<[A-Fa-f0-9]>, it will also match the 22 fullwidth equivalents, for
+example U+FF10: FULLWIDTH DIGIT ZERO.
+
+The Numeric type property has been extended to include the Unihan
+characters.
+
+There is a new Perl extension, the 'Present_In', or simply 'In',
+property. This is an extension of the Unicode Age property, but
+C<\p{In=5.0}> matches any code point whose usage has been determined
+I<as of> Unicode version 5.0. The C<\p{Age=5.0}> only matches code points
+added in I<precisely> version 5.0.
+
+A number of properties now have the correct values for unassigned
+code points. The affected properties are Bidi_Class, East_Asian_Width,
+Joining_Type, Decomposition_Type, Hangul_Syllable_Type, Numeric_Type,
+and Line_Break.
+
+The Default_Ignorable_Code_Point, ID_Continue, and ID_Start properties
+are now up to date with current Unicode definitions.
+
+Earlier versions of Perl erroneously exposed certain properties that
+are supposed to be Unicode internal-only. Use of these in regular
+expressions will now generate, if enabled, a deprecation warning message.
+The properties are: Other_Alphabetic, Other_Default_Ignorable_Code_Point,
+Other_Grapheme_Extend, Other_ID_Continue, Other_ID_Start, Other_Lowercase,
+Other_Math, and Other_Uppercase.
+
+It is now possible to change which Unicode properties Perl understands
+on a per-installation basis. As mentioned above, certain properties
+are turned off by default. These include all the Unihan properties
+(which should be accessible via the CPAN module Unicode::Unihan) and any
+deprecated or Unicode internal-only property that Perl has never exposed.
+
+The generated files in the C<lib/unicore/To> directory are now more
+clearly marked as being stable, directly usable by applications. New hash
+entries in them give the format of the normal entries, which allows for
+easier machine parsing. Perl can generate files in this directory for
+any property, though most are suppressed. You can find instructions
+for changing which are written in L<perluniprops>.
+
+=head1 Modules and Pragmata
+
+=head2 New Modules and Pragmata
+
+=over 4
+
+=item C<autodie>
+
+C<autodie> is a new lexically-scoped alternative for the C<Fatal> module.
+The bundled version is 2.06_01. Note that in this release, using a string
+eval when C<autodie> is in effect can cause the autodie behaviour to leak
+into the surrounding scope. See L<autodie/"BUGS"> for more details.
+
+Version 2.06_01 has been added to the Perl core.
+
+=item C<Compress::Raw::Bzip2>
+
+Version 2.024 has been added to the Perl core.
+
+=item C<overloading>
+
+C<overloading> allows you to lexically disable or enable overloading
+for some or all operations.
+
+Version 0.001 has been added to the Perl core.
+
+=item C<parent>
+
+C<parent> establishes an ISA relationship with base classes at compile
+time. It provides the key feature of C<base> without further unwanted
+behaviors.
+
+Version 0.223 has been added to the Perl core.
+
+=item C<Parse::CPAN::Meta>
+
+Version 1.40 has been added to the Perl core.
+
+=item C<VMS::DCLsym>
+
+Version 1.03 has been added to the Perl core.
+
+=item C<VMS::Stdio>
+
+Version 2.4 has been added to the Perl core.
+
+=item C<XS::APItest::KeywordRPN>
+
+Version 0.003 has been added to the Perl core.
+
+=back
+
+=head2 Updated Pragmata
+
+=over 4
+
+=item C<base>
+
+Upgraded from version 2.13 to 2.15.
+
+=item C<bignum>
+
+Upgraded from version 0.22 to 0.23.
+
+=item C<charnames>
+
+C<charnames> now contains the Unicode F<NameAliases.txt> database file.
+This has the effect of adding some extra C<\N> character names that
+formerly wouldn't have been recognised; for example, C<"\N{LATIN CAPITAL
+LETTER GHA}">.
+
+Upgraded from version 1.06 to 1.07.
+
+=item C<constant>
+
+Upgraded from version 1.13 to 1.20.
+
+=item C<diagnostics>
+
+C<diagnostics> now supports %.0f formatting internally.
+
+C<diagnostics> no longer suppresses C<Use of uninitialized value in range
+(or flip)> warnings. [perl #71204]
+
+Upgraded from version 1.17 to 1.19.
+
+=item C<feature>
+
+In C<feature>, the meaning of the C<:5.10> and C<:5.10.X> feature
+bundles has changed slightly. The last component, if any (i.e. C<X>) is
+simply ignored. This is predicated on the assumption that new features
+will not, in general, be added to maintenance releases. So C<:5.10>
+and C<:5.10.X> have identical effect. This is a change to the behaviour
+documented for 5.10.0.
+
+C<feature> now includes the C<unicode_strings> feature:
+
+ use feature "unicode_strings";
+
+This pragma turns on Unicode semantics for the case-changing operations
+(C<uc>, C<lc>, C<ucfirst>, C<lcfirst>) on strings that don't have the
+internal UTF-8 flag set, but that contain single-byte characters between
+128 and 255.
+
+Upgraded from version 1.11 to 1.16.
+
+=item C<less>
+
+C<less> now includes the C<stash_name> method to allow subclasses of
+C<less> to pick where in %^H to store their stash.
+
+Upgraded from version 0.02 to 0.03.
+
+=item C<lib>
+
+Upgraded from version 0.5565 to 0.62.
+
+=item C<mro>
+
+C<mro> is now implemented as an XS extension. The documented interface has
+not changed. Code relying on the implementation detail that some C<mro::>
+methods happened to be available at all times gets to "keep both pieces".
+
+Upgraded from version 1.00 to 1.02.
+
+=item C<overload>
+
+C<overload> now allow overloading of 'qr'.
+
+Upgraded from version 1.06 to 1.10.
+
+=item C<threads>
+
+Upgraded from version 1.67 to 1.75.
+
+=item C<threads::shared>
+
+Upgraded from version 1.14 to 1.32.
+
+=item C<version>
+
+C<version> now has support for L</Version number formats> as described
+earlier in this document and in its own documentation.
+
+Upgraded from version 0.74 to 0.82.
+
+=item C<warnings>
+
+C<warnings> has a new C<warnings::fatal_enabled()> function. It also
+includes a new C<illegalproto> warning category. See also L</New or
+Changed Diagnostics> for this change.
+
+Upgraded from version 1.06 to 1.09.
+
+=back
+
+=head2 Updated Modules
+
+=over 4
+
+=item C<Archive::Extract>
+
+Upgraded from version 0.24 to 0.38.
+
+=item C<Archive::Tar>
+
+Upgraded from version 1.38 to 1.54.
+
+=item C<Attribute::Handlers>
+
+Upgraded from version 0.79 to 0.87.
+
+=item C<AutoLoader>
+
+Upgraded from version 5.63 to 5.70.
+
+=item C<B::Concise>
+
+Upgraded from version 0.74 to 0.78.
+
+=item C<B::Debug>
+
+Upgraded from version 1.05 to 1.12.
+
+=item C<B::Deparse>
+
+Upgraded from version 0.83 to 0.96.
+
+=item C<B::Lint>
+
+Upgraded from version 1.09 to 1.11_01.
+
+=item C<CGI>
+
+Upgraded from version 3.29 to 3.48.
+
+=item C<Class::ISA>
+
+Upgraded from version 0.33 to 0.36.
+
+NOTE: C<Class::ISA> is deprecated and may be removed from a future
+version of Perl.
+
+=item C<Compress::Raw::Zlib>
+
+Upgraded from version 2.008 to 2.024.
+
+=item C<CPAN>
+
+Upgraded from version 1.9205 to 1.94_56.
+
+=item C<CPANPLUS>
+
+Upgraded from version 0.84 to 0.90.
+
+=item C<CPANPLUS::Dist::Build>
+
+Upgraded from version 0.06_02 to 0.46.
+
+=item C<Data::Dumper>
+
+Upgraded from version 2.121_14 to 2.125.
+
+=item C<DB_File>
+
+Upgraded from version 1.816_1 to 1.820.
+
+=item C<Devel::PPPort>
+
+Upgraded from version 3.13 to 3.19.
+
+=item C<Digest>
+
+Upgraded from version 1.15 to 1.16.
+
+=item C<Digest::MD5>
+
+Upgraded from version 2.36_01 to 2.39.
+
+=item C<Digest::SHA>
+
+Upgraded from version 5.45 to 5.47.
+
+=item C<Encode>
+
+Upgraded from version 2.23 to 2.39.
+
+=item C<Exporter>
+
+Upgraded from version 5.62 to 5.64_01.
+
+=item C<ExtUtils::CBuilder>
+
+Upgraded from version 0.21 to 0.27.
+
+=item C<ExtUtils::Command>
+
+Upgraded from version 1.13 to 1.16.
+
+=item C<ExtUtils::Constant>
+
+Upgraded from version 0.2 to 0.22.
+
+=item C<ExtUtils::Install>
+
+Upgraded from version 1.44 to 1.55.
+
+=item C<ExtUtils::MakeMaker>
+
+Upgraded from version 6.42 to 6.56.
+
+=item C<ExtUtils::Manifest>
+
+Upgraded from version 1.51_01 to 1.57.
+
+=item C<ExtUtils::ParseXS>
+
+Upgraded from version 2.18_02 to 2.21.
+
+=item C<File::Fetch>
+
+Upgraded from version 0.14 to 0.24.
+
+=item C<File::Path>
+
+Upgraded from version 2.04 to 2.08_01.
+
+=item C<File::Temp>
+
+Upgraded from version 0.18 to 0.22.
+
+=item C<Filter::Simple>
+
+Upgraded from version 0.82 to 0.84.
+
+=item C<Filter::Util::Call>
+
+Upgraded from version 1.07 to 1.08.
+
+=item C<Getopt::Long>
+
+Upgraded from version 2.37 to 2.38.
+
+=item C<IO>
+
+Upgraded from version 1.23_01 to 1.25_02.
+
+=item C<IO::Zlib>
+
+Upgraded from version 1.07 to 1.10.
+
+=item C<IPC::Cmd>
+
+Upgraded from version 0.40_1 to 0.54.
+
+=item C<IPC::SysV>
+
+Upgraded from version 1.05 to 2.01.
+
+=item C<Locale::Maketext>
+
+Upgraded from version 1.12 to 1.14.
+
+=item C<Locale::Maketext::Simple>
+
+Upgraded from version 0.18 to 0.21.
+
+=item C<Log::Message>
+
+Upgraded from version 0.01 to 0.02.
+
+=item C<Log::Message::Simple>
+
+Upgraded from version 0.04 to 0.06.
+
+=item C<Math::BigInt>
+
+Upgraded from version 1.88 to 1.89_01.
+
+=item C<Math::BigInt::FastCalc>
+
+Upgraded from version 0.16 to 0.19.
+
+=item C<Math::BigRat>
+
+Upgraded from version 0.21 to 0.24.
+
+=item C<Math::Complex>
+
+Upgraded from version 1.37 to 1.56.
+
+=item C<Memoize>
+
+Upgraded from version 1.01_02 to 1.01_03.
+
+=item C<MIME::Base64>
+
+Upgraded from version 3.07_01 to 3.08.
+
+=item C<Module::Build>
+
+Upgraded from version 0.2808_01 to 0.3603.
+
+=item C<Module::CoreList>
+
+Upgraded from version 2.12 to 2.29.
-=over 4
+=item C<Module::Load>
-=item Use of C<:=> to mean an empty attribute list is now deprecated.
+Upgraded from version 0.12 to 0.16.
-An accident of Perl's parser meant that these constructions were all
-equivalent:
+=item C<Module::Load::Conditional>
- my $pi := 4;
- my $pi : = 4;
- my $pi : = 4;
+Upgraded from version 0.22 to 0.34.
-with the C<:> being treated as the start of an attribute list, which
-ends before the C<=>. As whitespace is not significant here, all are
-parsed as an empty attribute list, hence all the above are equivalent
-to, and better written as
+=item C<Module::Loaded>
- my $pi = 4;
+Upgraded from version 0.01 to 0.06.
-because no attribute processing is done for an empty list.
+=item C<Module::Pluggable>
-As is, this meant that C<:=> cannot be used as a new token, without
-silently changing the meaning of existing code. Hence that particular
-form is now deprecated, and will become a syntax error. If it is
-absolutely necessary to have empty attribute lists (for example,
-because of a code generator) then avoid the warning by adding a space
-before the C<=>.
+Upgraded from version 3.6 to 3.9.
-=item C<< UNIVERSAL->import() >>
+=item C<Net::Ping>
-The method C<< UNIVERSAL->import() >> is now deprecated. Attempting to
-pass import arguments to a C<use UNIVERSAL> statement will result in a
-deprecation warning.
+Upgraded from version 2.33 to 2.36.
-=item Use of "goto" to jump into a construct is deprecated
+=item C<NEXT>
-Using C<goto> to jump from an outer scope into an inner scope is now
-deprecated. This rare use case was causing problems in the
-implementation of scopes.
+Upgraded from version 0.60_01 to 0.64.
-=item Deprecated Modules
+=item C<Object::Accessor>
-The following modules will be removed from the core distribution in a future
-release, and should be installed from CPAN instead. Distributions on CPAN
-which require these should add them to their prerequisites. The core versions
-of these modules warnings will issue a deprecation warning.
+Upgraded from version 0.32 to 0.36.
-=over
+=item C<Package::Constants>
-=item L<Class::ISA>
+Upgraded from version 0.01 to 0.02.
-=item L<Pod::Plainer>
+=item C<PerlIO>
-=item L<Shell>
+Upgraded from version 1.04 to 1.06.
-=item L<Switch>
+=item C<Pod::Parser>
-Switch is buggy and should be avoided. See L<perlsyn/"Switch
-statements"> for its replacement.
+Upgraded from version 1.35 to 1.37.
-=back
+=item C<Pod::Perldoc>
-=item suidperl
+Upgraded from version 3.14_02 to 3.15_02.
-C<suidperl> has been removed. It used to provide a mechanism to
-emulate setuid permission bits on systems that don't support it properly.
+=item C<Pod::Plainer>
-=item Assignment to $[
+Upgraded from version 0.01 to 1.02.
-=item attrs
+NOTE: C<Pod::Plainer> is deprecated and may be removed from a future
+version of Perl.
-Remove attrs, which has been deprecated since 1999-10-02.
+=item C<Pod::Simple>
-=item Use of the attribute :locked on subroutines.
+Upgraded from version 3.05 to 3.13.
-=item Use of "locked" with the attributes pragma.
+=item C<Safe>
-=item Use of "unique" with the attributes pragma.
+Upgraded from version 2.12 to 2.22.
-=item Numerous Perl 4-era libraries:
+=item C<SelfLoader>
-F<termcap.pl>, F<tainted.pl>, F<stat.pl>, F<shellwords.pl>, F<pwd.pl>,
-F<open3.pl>, F<open2.pl>, F<newgetopt.pl>, F<look.pl>, F<find.pl>,
-F<finddepth.pl>, F<importenv.pl>, F<hostname.pl>, F<getopts.pl>,
-F<getopt.pl>, F<getcwd.pl>, F<flush.pl>, F<fastcwd.pl>, F<exceptions.pl>,
-F<ctime.pl>, F<complete.pl>, F<cacheout.pl>, F<bigrat.pl>, F<bigint.pl>,
-F<bigfloat.pl>, F<assert.pl>, F<abbrev.pl>, F<dotsh.pl>, and
-F<timelocal.pl> are all now deprecated. Using them will incur a warning.
+Upgraded from version 1.11 to 1.17.
-=back
+=item C<Storable>
-=head1 Modules and Pragmata
+Upgraded from version 2.18 to 2.22.
-=head2 Dual-lifed modules moved
+=item C<Switch>
-Dual-lifed modules maintained primarily in the Perl core now live in dist/.
-Dual-lifed modules maintained primarily on CPAN now live in cpan/
+Upgraded from version 2.13 to 2.16.
-In previous releases of Perl, it was customary to enumerate all module
-changes in this section of the C<perldelta> file. From 5.11.0 forward
-only notable updates (such as new or deprecated modules ) will be listed
-in this section. For a complete reference to the versions of modules
-shipped in a given release of perl, please see L<Module::CoreList>.
+NOTE: C<Switch> is deprecated and may be removed from a future version
+of Perl.
-=head2 New Modules and Pragmata
+=item C<Sys::Syslog>
-=over 4
+Upgraded from version 0.22 to 0.27.
-=item *
+=item C<Term::ANSIColor>
-C<autodie>
+Upgraded from version 1.12 to 2.02.
-This is a new lexically-scoped alternative for the C<Fatal> module.
-The bundled version is 2.06_01. Note that in this release, using a string
-eval when C<autodie> is in effect can cause the autodie behaviour to leak
-into the surrounding scope. See L<autodie/"BUGS"> for more details.
+=item C<Term::UI>
-=item *
+Upgraded from version 0.18 to 0.20.
-C<Compress::Raw::Bzip2>
+=item C<Test>
-This has been added to the core (version 2.020).
+Upgraded from version 1.25 to 1.25_02.
-=item *
+=item C<Test::Harness>
-C<parent>
+Upgraded from version 2.64 to 3.17.
-This pragma establishes an ISA relationship with base classes at compile
-time. It provides the key feature of C<base> without further unwanted
-behaviors.
+=item C<Test::Simple>
-=item *
+Upgraded from version 0.72 to 0.94.
-C<Parse::CPAN::Meta>
+=item C<Text::Balanced>
-This has been added to the core (version 1.39).
+Upgraded from version 2.0.0 to 2.02.
-=back
+=item C<Text::ParseWords>
-=head2 Pragmata Changes
+Upgraded from version 3.26 to 3.27.
-=over 4
+=item C<Text::Soundex>
-=item *
+Upgraded from version 3.03 to 3.03_01.
-C<overloading>
+=item C<Thread::Queue>
-See L</"The C<overloading> pragma"> above.
+Upgraded from version 2.00 to 2.11.
-=item *
+=item C<Thread::Semaphore>
-C<attrs>
+Upgraded from version 2.01 to 2.09.
-The C<attrs> pragma has been removed. It had been marked as deprecated since
-5.6.0.
+=item C<Tie::RefHash>
-=item *
+Upgraded from version 1.37 to 1.38.
-C<charnames>
+=item C<Time::HiRes>
-The Unicode F<NameAliases.txt> database file has been added. This has the
-effect of adding some extra C<\N> character names that formerly wouldn't
-have been recognised; for example, C<"\N{LATIN CAPITAL LETTER GHA}">.
+Upgraded from version 1.9711 to 1.9719.
-=item *
+=item C<Time::Local>
-C<feature>
+Upgraded from version 1.18 to 1.1901_01.
-The meaning of the C<:5.10> and C<:5.10.X> feature bundles has
-changed slightly. The last component, if any (i.e. C<X>) is simply ignored.
-This is predicated on the assumption that new features will not, in
-general, be added to maintenance releases. So C<:5.10> and C<:5.10.X>
-have identical effect. This is a change to the behaviour documented for
-5.10.0.
+=item C<Time::Piece>
-=item *
+Upgraded from version 1.12 to 1.15.
-C<mro>
+=item C<Unicode::Collate>
-Upgraded from version 1.00 to 1.01. Performance for single inheritance is 40%
-faster - see L</"Performance Enhancements"> below.
+Upgraded from version 0.52 to 0.52_01.
-C<mro> is now implemented as an XS extension. The documented interface has not
-changed. Code relying on the implementation detail that some C<mro::>
-methods happened to be available at all times gets to "keep both pieces".
+=item C<Unicode::Normalize>
-=item *
+Upgraded from version 1.02 to 1.03.
-C<diagnostics>
+=item C<Win32>
-Supports %.0f formatting internally.
+Upgraded from version 0.34 to 0.39.
-=item *
+=item C<Win32API::File>
-C<overload>
+Upgraded from version 0.1001_01 to 0.1101.
-Allow overloading of 'qr'.
+=item C<XSLoader>
-=item *
+Upgraded from version 0.08 to 0.10.
-C<constant>
+=back
-Upgraded from version 1.19 to 1.20.
+=head2 Removed Modules and Pragmata
-=item *
+=over 4
-C<diagnostics>
+=item C<attrs>
-This pragma no longer suppresses C<Use of uninitialized value in range
-(or flip)> warnings. [perl #71204]
+Removed from the Perl core. Prior version was 1.02.
-=item *
+=item C<CPAN::API::HOWTO>
-C<feature>
+Removed from the Perl core. Prior version was 'undef'.
-Upgraded from 1.13 to 1.14. Added the C<unicode_strings> feature:
+=item C<CPAN::DeferedCode>
- use feature "unicode_strings";
+Removed from the Perl core. Prior version was 5.50.
-This pragma turns on Unicode semantics for the case-changing operations
-(C<uc>, C<lc>, C<ucfirst>, C<lcfirst>) on strings that don't have the
-internal UTF-8 flag set, but that contain single-byte characters between
-128 and 255.
+=item C<CPANPLUS::inc>
-=item *
+Removed from the Perl core. Prior version was 'undef'.
-C<threads>
+=item C<DCLsym>
-Upgraded from version 1.74 to 1.75.
+Removed from the Perl core. Prior version was 1.03.
-=item *
+=item C<ExtUtils::MakeMaker::bytes>
-C<less>
+Removed from the Perl core. Prior version was 6.42.
-Upgraded from version 0.02 to 0.03.
+=item C<ExtUtils::MakeMaker::vmsish>
-This version introduces the C<stash_name> method to allow subclasses of
-C<less> to pick where in %^H to store their stash.
+Removed from the Perl core. Prior version was 6.42.
-=item *
+=item C<Stdio>
-C<version>
+Removed from the Perl core. Prior version was 2.3.
-Upgraded from version 0.77 to 0.81.
+=item C<Test::Harness::Assert>
-This version adds support for L</Version number formats> as described earlier
-in this document and in its own documentation.
+Removed from the Perl core. Prior version was 0.02.
-=item *
+=item C<Test::Harness::Iterator>
-C<warnings>
+Removed from the Perl core. Prior version was 0.02.
-Upgraded from 1.07 to 1.09.
+=item C<Test::Harness::Point>
-Added new C<warnings::fatal_enabled()> function.
-This version adds the C<illegalproto> warning category. See also L</New or
-Changed Diagnostics> for this change.
+Removed from the Perl core. Prior version was 0.01.
-=back
+=item C<Test::Harness::Results>
+Removed from the Perl core. Prior version was 0.01.
-=head2 Updated Modules
+=item C<Test::Harness::Straps>
-=over 4
+Removed from the Perl core. Prior version was 0.26_01.
-=item XXX TODO RECALCULATE THIS VS 5.10.0
+=item C<Test::Harness::Util>
-=back
+Removed from the Perl core. Prior version was 0.01.
-=head2 Removed Modules and Pragmata
+=item C<XSSymSet>
-=over 4
+Removed from the Perl core. Prior version was 1.1.
-=item *
+=back
-C<Devel::DProf::V>
+=head2 Deprecated Modules and Pragmata
-Removed from the Perl core. Prior version was 'undef'.
+See L</Deprecated Modules> above.
-=back
=head1 Documentation
=item *
-L<perlhaiku>
-
-This contains instructions on how to build perl for the Haiku platform.
+L<perlhaiku> contains instructions on how to build perl for the Haiku
+platform.
=item *
-L<perlmroapi>
-
-This describes the new interface for pluggable Method Resolution Orders.
+L<perlmroapi> describes the new interface for pluggable Method Resolution
+Orders.
=item *
-L<perlperf>
-
-This document, by Richard Foley, provides an introduction to the use of
+L<perlperf>, by Richard Foley, provides an introduction to the use of
performance and optimization techniques which can be used with particular
reference to perl programs.
=item *
-L<perlrepository>
-
-This describes how to access the perl source using the I<git> version
-control system.
+L<perlrepository> describes how to access the perl source using the I<git>
+version control system.
=item *
=head2 Changes to Existing Documentation
-The various large F<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 F<Changes>, which just explains how that same information may
-be extracted from the git version control system.
-The file F<Porting/patching.pod> has been deleted, as it mainly described
+=over
+
+
+=item *
+
+The various large F<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 F<Changes>, which just explains how that same
+information may be extracted from the git version control system.
+
+=item *
+
+F<Porting/patching.pod> 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 L<perlrepository>.
-L<perlapi>, L<perlintern>, L<perlmodlib> and L<perltoc> are now all
-generated at build time, rather than being shipped as part of the release.
-=over
+=item *
+
+The syntax C<unless (EXPR) BLOCK else BLOCK> is now documented as valid,
+as is the syntax C<unless (EXPR) BLOCK elsif (EXPR) BLOCK ... else
+BLOCK>, although actually using the latter may not be the best idea for
+the readability of your source code.
+
=item *
=item *
-Documented C<when> as a syntax modifier
+Documented C<when> as a syntax modifier.
=item *
Correct previous documentation: v-strings are not deprecated
-With version objects, we need them to use MODULE VERSION syntax. This
+With version objects, we need them to use MODULE VERSION syntax. This
patch removes the deprecation notice.
=item *
-Added security contact information to L<perlsec>
+Security contact information is now part of L<perlsec>.
+
+=item *
-A significant fraction of the core documentation has been updated to clarify
-the behavior of Perl's Unicode handling.
+A significant fraction of the core documentation has been updated to
+clarify the behavior of Perl's Unicode handling.
Much of the remaining core documentation has been reviewed and edited
for clarity, consistent use of language, and to fix the spelling of Tom
Christiansen's name.
+=item *
+
The Pod specification (L<perlpodspec>) has been updated to bring the
specification in line with modern usage already supported by most Pod
-systems. A parameter string may now follow the format name in a
-"begin/end" region. Links to URIs with a text description are now
-allowed. The usage of C<LE<lt>"section"E<gt>> has been marked as
+systems. A parameter string may now follow the format name in a
+"begin/end" region. Links to URIs with a text description are now
+allowed. The usage of C<LE<lt>"section"E<gt>> has been marked as
deprecated.
+=item *
+
L<if.pm|if> has been documented in L<perlfunc/use> as a means to get
conditional loading of modules despite the implicit BEGIN block around
C<use>.
The documentation for C<$1> in perlvar.pod has been clarified.
+=item *
+
+C<\N{U+I<wide hex char>}> is now documented.
+
=back
-=head1 Performance Enhancements
+=head1 Selected Performance Enhancements
=over 4
=item *
-The implementation of C<C3> Method Resolution Order has been optimised -
-linearisation for classes with single inheritance is 40% faster. Performance
-for multiple inheritance is unchanged.
+The implementation of C<C3> Method Resolution Order has been
+optimised - linearisation for classes with single inheritance is 40%
+faster. Performance for multiple inheritance is unchanged.
=item *
Under C<use locale>, the locale-relevant information is now cached on
read-only values, such as the list returned by C<keys %hash>. This makes
-operations such as C<sort keys %hash> in the scope of C<use locale> much
-faster.
+operations such as C<sort keys %hash> in the scope of C<use locale>
+much faster.
=item *
=item *
-Faster C<Perl_sv_utf8_upgrade()>
+C<Perl_sv_utf8_upgrade()> is now faster.
+
+=item *
+
+C<keys> on empty hash is now faster.
=item *
-Speed up C<keys> on empty hash
+C<if (%foo)> has been optimized to be faster than C<if (keys %foo)>.
=item *
-C<if (%foo)> has been optimized to be faster than C<if (keys %foo)>
+The string repetition operator (C<$str x $num>) is now several times
+faster when C<$str> has length one or C<$num> is large.
=item *
Reversing an array to itself (as in C<@a = reverse @a>) in void context
-now happens in-place and is several orders of magnitude faster than it
-used to be. It will also preserve non-existent elements whenever
-possible, i.e. for non magical arrays or tied arrays with C<EXISTS> and
-C<DELETE> methods.
+now happens in-place and is several orders of magnitude faster than
+it used to be. It will also preserve non-existent elements whenever
+possible, i.e. for non magical arrays or tied arrays with C<EXISTS>
+and C<DELETE> methods.
=back
=head1 Installation and Configuration Improvements
-=head2 F<ext/> reorganisation
-
-The layout of directories in F<ext> has been revised. Specifically, all
-extensions are now flat, and at the top level, with C</> in pathnames
-replaced by C<->, so that F<ext/Data/Dumper/> is now F<ext/Data-Dumper/>,
-etc. The names of the extensions as specified to F<Configure>, and as
-reported by C<%Config::Config> under the keys C<dynamic_ext>,
-C<known_extensions>, C<nonxs_ext> and C<static_ext> have not changed, and
-still use C</>. Hence this change will not have any affect once perl is
-installed. C<Safe> has been split out from being part of C<Opcode>, and
-C<mro> is now an extension in its own right.
-
-Nearly all dual-life modules have been moved from F<lib> to F<ext>, and will
-now appear as known C<nonxs_ext>. This will made no difference to the
-structure of an installed perl, nor will the modules installed differ,
-unless you run F<Configure> with options to specify an exact list of
-extensions to build. In this case, you will rapidly become aware that you
-need to add to your list, because various modules needed to complete the
-build, such as C<ExtUtils::ParseXS>, have now become extensions, and
-without them the build will fail well before it attempts to run the
-regression tests.
-
-=head2 Configuration improvements
-
-If C<vendorlib> and C<vendorarch> are the same, then they are only added to
-C<@INC> once.
+=over 4
+
+=item *
+
+L<perlapi>, L<perlintern>, L<perlmodlib> and L<perltoc> are now all
+generated at build time, rather than being shipped as part of the release.
+
+=item *
+
+If C<vendorlib> and C<vendorarch> are the same, then they are only added
+to C<@INC> once.
+
+=item *
C<$Config{usedevel}> and the C-level C<PERL_USE_DEVEL> are now defined if
perl is built with C<-Dusedevel>.
+=item *
+
F<Configure> will enable use of C<-fstack-protector>, to provide protection
against stack-smashing attacks, if the compiler supports it.
+=item *
+
F<Configure> will now determine the correct prototypes for re-entrant
functions and for C<gconvert> if you are using a C++ compiler rather
than a C compiler.
+=item *
+
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 C<perl -v> and C<perl -V>. Unpushed local commits
are automatically added to the list of local patches displayed by
C<perl -V>.
-USE_ATTRIBUTES_FOR_PERLIO is now reported in the compile-time options
-listed by the C<-V> switch.
+=item *
+
+Perl now supports SystemTap's C<dtrace> compatibility layer and an
+issue with linking C<miniperl> has been fixed in the process.
-=head2 Compilation improvements
+=item *
+
+perldoc now uses C<less -R> instead of C<less> for improved behaviour
+in the face of C<groff>'s new usage of ANSI escape codes.
+
+=item *
+
+
+C<perl -V> now reports use of the compile-time options C<USE_PERL_ATOF> and
+C<USE_ATTRIBUTES_FOR_PERLIO>.
+
+=item *
As part of the flattening of F<ext>, all extensions on all platforms are
built by F<make_ext.pl>. This replaces the Unix-specific
F<ext/util/make_ext>, VMS-specific F<make_ext.com> and Win32-specific
F<win32/buildext.pl>.
-=head1 Changed Internals
+=back
-=over 4
+=head1 Internal Changes
-=item *
+Each release of Perl sees numerous internal changes which shouldn't
+affect day to day usage but may still be notable for developers working
+with Perl's source code.
-C<Perl_pmflag> has been removed from the public API. Calling it now
-generates a deprecation warning, and it will be removed in a future
-release. Although listed as part of the API, it was never documented,
-and only ever used in F<toke.c>, and prior to 5.10, F<regcomp.c>. In
-core, it has been replaced by a static function.
+=over
=item *
-Perl_magic_setmglob now knows about globs, fixing RT #71254.
+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.
=item *
-TODO: C<SVt_RV> is gone. RVs are now stored in IVs
+The internal structure of the dual-life modules traditionally found in
+the F<lib/> and F<ext/> directories in the perl source has changed
+significantly. Where possible, dual-lifed modules have been extracted
+from F<lib/> and F<ext/>.
+
+Dual-lifed modules maintained by Perl's developers as part of the Perl
+core now live in F<dist/>. Dual-lifed modules maintained primarily on
+CPAN now live in F<cpan/>. When reporting a bug in a module located
+under F<cpan/>, please send your bug report directly to the module's
+bug tracker or author, rather than Perl's bug tracker.
=item *
-TODO: REGEXPs are first class
+C<\N{...}> now compiles better, always forces UTF-8 internal representation
+
+Perl's developers have fixed several problems with the recognition of
+C<\N{...}> constructs. As part of this, perl will store any scalar
+or regex containing C<\N{I<name>}> or C<\N{U+I<wide hex char>}> in its
+definition in UTF-8 format. (This was true previously for all occurences
+of C<\N{I<name>}> that did not use a custom translator, but now it's
+always true.)
=item *
-TODO: OOK is reworked, such that an OOKed scalar is PV not PVIV
+Perl_magic_setmglob now knows about globs, fixing RT #71254.
=item *
-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.
+C<SVt_RV> no longer exists. RVs are now stored in IVs.
=item *
-C<Perl_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.
+C<Perl_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.
=item *
=item *
-C<SVf_UTF8>
-
-This will call C<SvUTF8_on()> for you. (Note that this does not convert an
-sequence of ISO 8859-1 characters to UTF-8). A wrapper, C<newSVpvn_utf8()>
-is available for this.
+C<SVf_UTF8> will call C<SvUTF8_on()> for you. (Note that this does
+not convert an sequence of ISO 8859-1 characters to UTF-8). A wrapper,
+C<newSVpvn_utf8()> is available for this.
=item *
-C<SVs_TEMP>
-
-Call C<Perl_sv_2mortal()> on the new SV.
+C<SVs_TEMP> now calls C<Perl_sv_2mortal()> on the new SV.
=back
=item *
-The functions C<PerlIO_find_layer> and C<PerlIO_list_alloc> are now
-exported.
+Perl now exports the functions C<PerlIO_find_layer> and C<PerlIO_list_alloc>.
=item *
-C<PL_na> has been exterminated from the core code, replaced by local STRLEN
-temporaries, or C<*_nolen()> calls. Either approach is faster than C<PL_na>,
-which is a pointer dereference into the interpreter structure under ithreads,
-and a global variable otherwise.
+C<PL_na> has been exterminated from the core code, replaced by local
+STRLEN temporaries, or C<*_nolen()> calls. Either approach is faster than
+C<PL_na>, which is a pointer dereference into the interpreter structure
+under ithreads, and a global variable otherwise.
=item *
-C<Perl_mg_free()> used to leave freed memory accessible via C<SvMAGIC()> on
-the scalar. It now updates the linked list to remove each piece of magic
-as it is freed.
+C<Perl_mg_free()> used to leave freed memory accessible via C<SvMAGIC()>
+on the scalar. It now updates the linked list to remove each piece of
+magic as it is freed.
=item *
-Under ithreads, the regex in C<PL_reg_curpm> is now reference counted. This
-eliminates a lot of hackish workarounds to cope with it not being reference
-counted.
+Under ithreads, the regex in C<PL_reg_curpm> is now reference
+counted. This eliminates a lot of hackish workarounds to cope with it
+not being reference counted.
=item *
=item *
-SV allocation tracing has been added to the diagnostics enabled by C<-Dm>.
-The tracing can alternatively output via the C<PERL_MEM_LOG> mechanism, if
-that was enabled when the F<perl> binary was compiled.
-
-=item *
-
-Smartmatch resolution tracing has been added as a new diagnostic. Use C<-DM> to
-enable it.
-
-=item *
-
-A new debugging flag C<-DB> now dumps subroutine definitions, leaving
-C<-Dx> for its original purpose of dumping syntax trees.
-
-=item *
-
-Uses of C<Nullav>, C<Nullcv>, C<Nullhv>, C<Nullop>, C<Nullsv> etc have been
-replaced by C<NULL> in the core code, and non-dual-life modules, as C<NULL>
-is clearer to those unfamiliar with the core code.
+Uses of C<Nullav>, C<Nullcv>, C<Nullhv>, C<Nullop>, C<Nullsv> etc have
+been replaced by C<NULL> in the core code, and non-dual-life modules,
+as C<NULL> is clearer to those unfamiliar with the core code.
=item *
not cast away C<const>, returning a C<void *>. Macros C<MUTABLE_SV(av)>,
C<MUTABLE_SV(cv)> etc build on this, casting to C<AV *> etc without
casting away C<const>. This allows proper compile-time auditing of
-C<const> correctness in the core, and helped picked up some errors (now
-fixed).
+C<const> correctness in the core, and helped picked up some errors
+(now fixed).
=item *
=head1 Testing
-=head2 New Tests
+=head2 Testing improvements
+
+=over 4
+
+=item Parallel tests
+
+The core distribution can now run its regression tests in parallel on
+Unix-like platforms. Instead of running C<make test>, set C<TEST_JOBS> in
+your environment to the number of tests to run in parallel, and run
+C<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
+L<TAP::Harness> needs to be able to schedule individual non-conflicting test
+scripts itself, and there is no standard interface to C<make> utilities to
+interact with their job schedulers.
+
+Note that currently some test scripts may fail when run in parallel (most
+notably C<ext/IO/t/io_dir.t>). If necessary run just the failing scripts
+again sequentially and see if the failures go away.
+
+=item Test harness flexibility
+
+It's now possible to override C<PERL5OPT> and friends in F<t/TEST>
+
+=item Test watchdog
-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 C<make test> and C<make test_harness> run to
-completion automatically. (Jerry Hedden).
+completion automatically.
+
+
+=back
-Some core-specific tests have been added:
+=head2 New Tests
+
+Perl's developers have added a number of new tests to the core.
+In addition to the items listed below, many modules updated from CPAN
+incorporate new tests.
=over 4
=item *
-F<t/porting/manifest.t> now tests that all files listed in MANIFEST are present.
+F<t/porting/manifest.t> now tests that all files listed in MANIFEST
+are present.
=item *
-F<t/op/while_readdir.t>
-
-Test that a bare readdir in while loop sets $_.
+F<t/op/while_readdir.t> tests that a bare readdir in while loop sets $_.
=item *
-F<t/comp/retainedlines.t>
-
-Check that the debugger can retain source lines from C<eval>.
+F<t/comp/retainedlines.t> checks that the debugger can retain source
+lines from C<eval>.
=item *
-F<t/io/perlio_fail.t>
-
-Check that bad layers fail.
+F<t/io/perlio_fail.t> checks that bad layers fail.
=item *
-F<t/io/perlio_leaks.t>
-
-Check that PerlIO layers are not leaking.
+F<t/io/perlio_leaks.t> checks that PerlIO layers are not leaking.
=item *
-F<t/io/perlio_open.t>
-
-Check that certain special forms of open work.
+F<t/io/perlio_open.t> checks that certain special forms of open work.
=item *
-F<t/io/perlio.t>
-
-General PerlIO tests.
+F<t/io/perlio.t> includes general PerlIO tests.
=item *
-F<t/io/pvbm.t>
-
-Check that there is no unexpected interaction between the internal types
-C<PVBM> and C<PVGV>.
+F<t/io/pvbm.t> checks that there is no unexpected interaction between
+the internal types C<PVBM> and C<PVGV>.
=item *
-F<t/mro/package_aliases.t>
-
-Check that mro works properly in the presence of aliased packages.
+F<t/mro/package_aliases.t> checks that mro works properly in the presence
+of aliased packages.
=item *
-F<t/op/dbm.t>
-
-Tests for C<dbmopen> and C<dbmclose>.
+F<t/op/dbm.t> tests C<dbmopen> and C<dbmclose>.
=item *
-F<t/op/index_thr.t>
-
-Tests for the interaction of C<index> and threads.
+F<t/op/index_thr.t> tests the interaction of C<index> and threads.
=item *
-F<t/op/pat_thr.t>
-
-Tests for the interaction of esoteric patterns and threads.
+F<t/op/pat_thr.t> tests the interaction of esoteric patterns and threads.
=item *
-F<t/op/qr_gc.t>
-
-Test that C<qr> doesn't leak.
+F<t/op/qr_gc.t> tests that C<qr> doesn't leak.
=item *
-F<t/op/reg_email_thr.t>
-
-Tests for the interaction of regex recursion and threads.
+F<t/op/reg_email_thr.t> tests the interaction of regex recursion and threads.
=item *
-F<t/op/regexp_qr_embed_thr.t>
-
-Tests for the interaction of patterns with embedded C<qr//> and threads.
+F<t/op/regexp_qr_embed_thr.t> tests the interaction of patterns with
+embedded C<qr//> and threads.
=item *
-F<t/op/regexp_unicode_prop.t>
-
-Tests for Unicode properties in regular expressions.
+F<t/op/regexp_unicode_prop.t> tests Unicode properties in regular
+expressions.
=item *
-F<t/op/regexp_unicode_prop_thr.t>
-
-Tests for the interaction of Unicode properties and threads.
+F<t/op/regexp_unicode_prop_thr.t> tests the interaction of Unicode
+properties and threads.
=item *
-F<t/op/reg_nc_tie.t>
-
-Test the tied methods of C<Tie::Hash::NamedCapture>.
+F<t/op/reg_nc_tie.t> tests the tied methods of C<Tie::Hash::NamedCapture>.
=item *
-F<t/op/reg_posixcc.t>
-
-Check that POSIX character classes behave consistently.
+F<t/op/reg_posixcc.t> checks that POSIX character classes behave
+consistently.
=item *
-F<t/op/re.t>
-
-Check that exportable C<re> functions in F<universal.c> work.
+F<t/op/re.t> checks that exportable C<re> functions in F<universal.c> work.
=item *
-F<t/op/setpgrpstack.t>
-
-Check that C<setpgrp> works.
+F<t/op/setpgrpstack.t> checks that C<setpgrp> works.
=item *
-F<t/op/substr_thr.t>
-
-Tests for the interaction of C<substr> and threads.
+F<t/op/substr_thr.t> tests the interaction of C<substr> and threads.
=item *
-F<t/op/upgrade.t>
-
-Check that upgrading and assigning scalars works.
+F<t/op/upgrade.t> checks that upgrading and assigning scalars works.
=item *
-F<t/uni/lex_utf8.t>
-
-Check that Unicode in the lexer works.
+F<t/uni/lex_utf8.t> checks that Unicode in the lexer works.
=item *
-F<t/uni/tie.t>
-
-Check that Unicode and C<tie> work.
+F<t/uni/tie.t> checks that Unicode and C<tie> work.
=item *
-F<t/comp/final_line_num.t>
-
-See if line numbers are correct at EOF
+F<t/comp/final_line_num.t> tests whether line numbers are correct at EOF
=item *
-F<t/comp/form_scope.t>
-
-See if format scoping works
+F<t/comp/form_scope.t> tests format scoping.
=item *
-F<t/comp/line_debug.t>
+F<t/comp/line_debug.t> tests whether C<< @{"_<$file"} >> works.
-See if C<< @{"_<$file"} >> works
+=item *
+
+F<t/op/filetest_t.t> tests if -t file test works.
=item *
-F<t/op/filetest_t.t>
+F<t/op/qr.t> tests C<qr>.
+
+=item *
-See if -t file test works
+F<t/op/utf8cache.t> tests malfunctions of the utf8 cache.
=item *
-F<t/op/qr.t>
+F<t/re/uniprops.t> test unicodes C<\p{}> regex constructs.
-See if qr works
+=item *
+
+F<t/op/filehandle.t> tests some suitably portable filetest operators
+to check that they work as expected, particularly in the light of some
+internal changes made in how filehandles are blessed.
=item *
-F<t/op/utf8cache.t>
+F<t/op/time_loop.t> tests that unix times greater than C<2**63>, which
+can now be handed to C<gmtime> and C<localtime>, do not cause an internal
+overflow or an excessively long loop.
-Tests malfunctions of utf8 cache
+=back
-=item *
-F<t/re/uniprops.t>
+=head1 New or Changed Diagnostics
-Test unicode \p{} regex constructs
+=head2 New Diagnostics
-=back
+=over
-=head2 Testing improvements
+=item *
-=over 4
+SV allocation tracing has been added to the diagnostics enabled by C<-Dm>.
+The tracing can alternatively output via the C<PERL_MEM_LOG> mechanism, if
+that was enabled when the F<perl> binary was compiled.
=item *
-It's now possible to override C<PERL5OPT> and friends in F<t/TEST>
+Smartmatch resolution tracing has been added as a new diagnostic. Use
+C<-DM> to enable it.
-=back
+=item *
+A new debugging flag C<-DB> now dumps subroutine definitions, leaving
+C<-Dx> for its original purpose of dumping syntax trees.
-=head1 New or Changed Diagnostics
+=item *
-Several new diagnostics, see L<perldiag> for details.
+Perl 5.12 provides a number of new diagnostic messages to help you write
+better code. See L<perldiag> for details of these new messages.
=over 4
=item *
-New warning category C<illegalproto>
+C<lvalue attribute ignored after the subroutine has been defined>
-The two warnings :
-
- Illegal character in prototype for %s : %s
- Prototype after '%c' for %s : %s
+This new warning is issued when one attempts to mark a subroutine as
+lvalue after it has been defined.
-have been moved from the C<syntax> top-level warnings category into a new
-first-level category, C<illegalproto>. These two warnings are currently the
-only ones emitted during parsing of an invalid/illegal prototype, so one
-can now do
+=item *
- no warnings 'illegalproto';
+Perl now warns you if C<++> or C<--> are unable to change the value
+because it's beyond the limit of representation.
-to suppress only those, but not other syntax-related warnings. Warnings where
-prototypes are changed, ignored, or not met are still in the C<prototype>
-category as before. (Matt S. Trout)
+This uses a new warnings category: "imprecision".
=item *
-lvalue attribute ignored after the subroutine has been defined
+C<lc>, C<uc>, C<lcfirst>, and C<ucfirst> warn when passed undef.
+
+=item *
-This new warning is issued when one attempts to mark a subroutine as
-lvalue after it has been defined.
+C<Show constant in "Useless use of a constant in void context">
=item *
-warn if C<++> or C<--> are unable to change the value because it's
-beyond the limit of representation
+C<Prototype after '%s'>
-This uses a new warnings category: "imprecision".
+=item *
-=item *
+C<panic: sv_chop %s>
+
+This new fatal error occurs when the C routine C<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.
-C<lc>, C<uc>, C<lcfirst>, and C<ucfirst> warn when passed undef.
=item *
-Show constant in "Useless use of a constant in void context"
+The fatal error C<Malformed UTF-8 returned by \N> is now produced if the
+C<charnames> handler returns malformed UTF-8.
=item *
-Make the new warning report undef constants as undef
+If an unresolved named character or sequence was encountered when
+compiling a regex pattern then the fatal error C<\N{NAME} must be resolved
+by the lexer> is now produced. This can happen, for example, when using a
+single-quotish context like C<$re = '\N{SPACE}'; /$re/;>. See L<perldiag>
+for more examples of how the lexer can get bypassed.
=item *
-Add a new warning, "Prototype after '%s'"
+C<Invalid hexadecimal number in \N{U+...}> is a new fatal error
+triggered when the character constant represented by C<...> is not a
+valid hexadecimal number.
=item *
-Tweak the "Illegal character in prototype" warning so it's more precise
-when reporting illegal characters after _
+The new meaning of C<\N> as C<[^\n]> is not valid in a bracketed character
+class, just like C<.> in a character class loses its special meaning,
+and will cause the fatal error C<\N in a character class must be a named
+character: \N{...}>.
=item *
-Correct the unintended interpolation of C<$\> in regex
+The rules on what is legal for the C<...> in C<\N{...}> have been
+tightened up so that unless the C<...> begins with an alphabetic
+character and continues with a combination of alphanumerics, dashes,
+spaces, parentheses or colons then the warning C<Deprecated character(s)
+in \N{...} starting at '%s'> is now issued.
=item *
-Make overflow warnings in C<gmtime> and C<localtime> only occur when
-warnings are enabled
+The warning C<Using just the first characters returned by \N{}> will
+be issued if the C<charnames> handler returns a sequence of characters
+which exceeds the limit of the number of characters that can be used. The
+message will indicate which characters were used and which were discarded.
-=item *
+=back
-Improve mro merging error messages.
+=back
+
+=head2 Changed Diagnostics
-They are now very similar to those produced by Algorithm::C3.
+A number of existing diagnostic messages have been improved or corrected:
+
+=over
=item *
-Amelioration of the error message "Unrecognized character %s in column %d"
+A new warning category C<illegalproto> allows finer-grained control of
+warnings around function prototypes.
-Changes the error message to "Unrecognized character %s; marked by E<lt>--
-HERE after %sE<lt>-- HERE near column %d". This should make it a little
-simpler to spot and correct the suspicious character.
+The two warnings:
+
+=over
+
+=item C<Illegal character in prototype for %s : %s>
+
+=item C<Prototype after '%c' for %s : %s>
+
+=back
+
+have been moved from the C<syntax> top-level warnings category into a new
+first-level category, C<illegalproto>. These two warnings are currently
+the only ones emitted during parsing of an invalid/illegal prototype,
+so one can now use
+
+ no warnings 'illegalproto';
+
+to suppress only those, but not other syntax-related warnings. Warnings
+where prototypes are changed, ignored, or not met are still in the
+C<prototype> category as before.
=item *
-Explicitely point to C<$.> when it causes an uninitialized warning for
-ranges in scalar context
+C<Deep recursion on subroutine "%s">
+
+It is now possible to change the depth threshold for this warning from the
+default of 100, by recompiling the F<perl> binary, setting the C
+pre-processor macro C<PERL_SUB_DEPTH_WARN> to the desired value.
=item *
-C<split> now warns when called in void context
+C<Illegal character in prototype> warning is now more precise
+when reporting illegal characters after _
=item *
-C<printf>-style functions called with too few arguments will now issue the
-warning C<"Missing argument in %s"> [perl #71000]
+mro merging error messages are now very similar to those produced by
+L<Algorithm::C3>.
=item *
-C<panic: sv_chop %s>
+Amelioration of the error message "Unrecognized character %s in column %d"
-This new fatal error occurs when the C routine C<Perl_sv_chop()> was
-passed a position that is not within the scalar's string buffer. This
-could be caused by buggy XS code, and at this point recovery is not
-possible.
+Changes the error message to "Unrecognized character %s; marked by E<lt>--
+HERE after %sE<lt>-- HERE near column %d". This should make it a little
+simpler to spot and correct the suspicious character.
=item *
-C<Deep recursion on subroutine "%s">
+Perl now explicitly points to C<$.> when it causes an uninitialized
+warning for ranges in scalar context.
-It is now possible to change the depth threshold for this warning from the
-default of 100, by recompiling the F<perl> binary, setting the C
-pre-processor macro C<PERL_SUB_DEPTH_WARN> to the desired value.
+=item *
+
+C<split> now warns when called in void context.
+
+=item *
+
+C<printf>-style functions called with too few arguments will now issue the
+warning C<"Missing argument in %s"> [perl #71000]
=item *
=item *
-The Windows select() implementation now supports all empty C<fd_set>s
-more correctly.
-
-=item *
-
-The "syntax" category was removed from 5 warnings that should only be in
-"deprecated".
+The C<syntax> category was removed from 5 warnings that should only be in
+C<deprecated>.
=item *
Three fatal C<pack>/C<unpack> error messages have been normalized to
-"panic: %s"
+C<panic: %s>
=item *
-"Unicode character is illegal" has been rephrased to be more accurate
+C<Unicode character is illegal> has been rephrased to be more accurate
It now reads C<Unicode non-character is illegal in interchange> and the
perldiag documentation has been expanded a bit.
=item *
-Perl now defaults to issuing a warning if a deprecated language feature
-is used.
+Currently, all but the first of the several characters that the
+C<charnames> handler may return are discarded when used in a regular
+expression pattern bracketed character class. If this happens then the
+warning C<Using just the first character returned by \N{} in character
+class> will be issued.
-To disable this feature in a given lexical scope, you should use C<no
-warnings 'deprecated';> For information about which language features
-are deprecated and explanations of various deprecation warnings, please
-see L<perldiag.pod>
+=item *
+
+The warning C<Missing right brace on \N{} or unescaped left brace after
+\N. Assuming the latter> will be issued if Perl encounters a C<\N{>
+but doesn't find a matching C<}>. In this case Perl doesn't know if it
+was mistakenly omitted, or if "match non-newline" followed by "match
+a C<{>" was desired. It assumes the latter because that is actually a
+valid interpretation as written, unlike the other case. If you meant
+the former, you need to add the matching right brace. If you did mean
+the latter, you can silence this warning by writing instead C<\N\{>.
+
+=item *
+
+C<gmtime> and C<localtime> called with numbers smaller than they can
+reliably handle will now issue the warnings C<gmtime(%.0f) too small>
+and C<localtime(%.0f) too small>.
=back
-The following diagnostics have been removed:
+The following diagnostic messages have been removed:
=over 4
C<Can't locate package %s for the parents of %s>
-This warning has been removed. In general, it only got produced in
+In general this warning it only got produced in
conjunction with other warnings, and removing it allowed an ISA lookup
optimisation to be added.
=item *
-F<h2ph>
-
-Now looks in C<include-fixed> too, which is a recent addition to gcc's
-search path.
+F<h2ph> now looks in C<include-fixed> too, which is a recent addition
+to gcc's search path.
=item *
-F<h2xs>
-
-No longer incorrectly treats enum values like macros (Daniel Burr).
-
-Now handles C++ style constants (C<//>) properly in enums. (A patch from
-Rainer Weikusat was used; Daniel Burr also proposed a similar fix).
+F<h2xs> no longer incorrectly treats enum values like macros.
+It also now handles C++ style comments (C<//>) properly in enums.
=item *
-F<perl5db.pl>
-
-C<LVALUE> subroutines now work under the debugger.
-
-The debugger now correctly handles proxy constant subroutines, and
+F<perl5db.pl> now supports C<LVALUE> subroutines. Additionally, the
+debugger now correctly handles proxy constant subroutines, and
subroutine stubs.
=item *
-F<perlbug>
-
-F<perlbug> now uses C<%Module::CoreList::bug_tracker> to print out upstream bug
-tracker URLs.
-
-Where the user names a module that their bug report is about, and we know the
-URL for its upstream bug tracker, provide a message to the user explaining
-that the core copies the CPAN version directly, and provide the URL for
-reporting the bug directly to upstream.
-
-=item *
-
-F<perlthanks>
+F<perlbug> now uses C<%Module::CoreList::bug_tracker> to print out
+upstream bug tracker URLs. If a user identifies a particular module
+as the topic of their bug report and we're able to divine the URL for
+its upstream bug tracker, perlbug now provide a message to the user
+explaining that the core copies the CPAN version directly, and provide
+the URL for reporting the bug directly to the upstream author.
-Perl 5.11.0 added a new utility F<perlthanks>, which is a variant of
-F<perlbug>, 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.
+F<perlbug> no longer reports "Message sent" when it hasn't actually sent
+the message
=item *
-F<perlbug>
-
-No longer reports "Message sent" when it hasn't actually sent the message
+F<perlthanks> is a new utility for sending non-bug-reports to the
+authors and maintainers of Perl. Getting nothing but bug reports can
+become a bit demoralising. If Perl 5.12 works well for you, please try
+out F<perlthanks>. It will make the developers smile.
=item *
-F<a2p>
-
-Fixed bugs with the match() operator in list context, remove mention of
-C<$[>.
+Perl's developers have fixed bugs in F<a2p> having to do with the
+C<match()> operator in list context. Additionally, F<a2p> no longer
+generates code that uses the C<$[> variable.
=back
=item *
-Ensure that pp_qr returns a new regexp SV each time. Resolves RT #69852.
+U+0FFFF is now a legal character in regular expressions.
+
+=item *
+
+pp_qr now always returns a new regexp SV. Resolves RT #69852.
-Instead of returning a(nother) reference to the (pre-compiled) regexp in the
-optree, use reg_temp_copy() to create a copy of it, and return a reference to
-that. This resolves issues about Regexp::DESTROY not being called in a timely
-fashion (the original bug tracked by RT #69852), as well as bugs related to
-blessing regexps, and of assigning to regexps, as described in correspondence
-added to the ticket.
+Instead of returning a(nother) reference to the (pre-compiled) regexp
+in the optree, use reg_temp_copy() to create a copy of it, and return a
+reference to that. This resolves issues about Regexp::DESTROY not being
+called in a timely fashion (the original bug tracked by RT #69852), as
+well as bugs related to blessing regexps, and of assigning to regexps,
+as described in correspondence added to the ticket.
It transpires that we also need to undo the SvPVX() sharing when ithreads
-cloning a Regexp SV, because mother_re is set to NULL, instead of a cloned
-copy of the mother_re. This change might fix bugs with regexps and threads in
-certain other situations, but as yet neither tests nor bug reports have
-indicated any problems, so it might not actually be an edge case that it's
-possible to reach.
+cloning a Regexp SV, because mother_re is set to NULL, instead of a
+cloned copy of the mother_re. This change might fix bugs with regexps
+and threads in certain other situations, but as yet neither tests nor
+bug reports have indicated any problems, so it might not actually be an
+edge case that it's possible to reach.
=item *
-Several compilation errors and segfaults when perl was built with C<-Dmad> were fixed.
+Several compilation errors and segfaults when perl was built with C<-Dmad>
+were fixed.
=item *
C<-t> should only return TRUE for file handles connected to a TTY
-The Microsoft C version of C<isatty()> returns TRUE for all
-character mode devices, including the F</dev/null>-style "nul"
-device and printers like "lpt1".
+The Microsoft C version of C<isatty()> returns TRUE for all character mode
+devices, including the F</dev/null>-style "nul" device and printers like
+"lpt1".
=item *
=item *
-Using named subroutines with C<sort> should no longer lead to bus errors [perl
-#71076]
+Using named subroutines with C<sort> should no longer lead to bus errors
+[perl #71076]
=item *
C<kill> is now fatal when called on non-numeric process identifiers.
Previously, an C<undef> process identifier would be interpreted as a
request to kill process 0, which would terminate the current process
-group on POSIX systems. Since process identifiers are always integers,
+group on POSIX systems. Since process identifiers are always integers,
killing a non-numeric process is now fatal.
=item *
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 C<@_>. The optimisation has been re-instated, and
-the performance regression fixed. (This fix is also present in 5.10.1)
+the performance regression fixed. (This fix is also present in 5.10.1)
=item *
=item *
-C<< $object-E<gt>isa('Foo') >> would report false if the package C<Foo> didn't
-exist, even if the object's C<@ISA> contained C<Foo>.
+C<< $object-E<gt>isa('Foo') >> would report false if the package C<Foo>
+didn't exist, even if the object's C<@ISA> contained C<Foo>.
=item *
=item *
The block form of C<eval> is now specifically trappable by C<Safe> and
-C<ops>. Previously it was erroneously treated like string C<eval>.
+C<ops>. Previously it was erroneously treated like string C<eval>.
=item *
=item *
-On Windows, C<'.\foo'> and C<'..\foo'> were treated differently than
-C<'./foo'> and C<'../foo'> by C<do> and C<require> [RT #63492].
-
-=item *
-
Assigning a format to a glob could corrupt the format; e.g.:
*bar=*foo{FORMAT}; # foo format now bad
=item *
-Under C<use filetest 'access'>, C<-x> was using the wrong access mode. This
-has been fixed [RT #49003].
+Under C<use filetest 'access'>, C<-x> was using the wrong access
+mode. This has been fixed [RT #49003].
=item *
In C<unpack>, the use of C<()> 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].
+ways, including SEGVs. This is now fixed [RT #50256].
=item *
=item *
-Previously missing files from Unicode 5.1 Character Database are now included.
+Perl now includes previously missing files from the Unicode Character
+Database.
=item *
-C<TMPDIR> is now honored when opening an anonymous temporary file
+Perl now honors C<TMPDIR> when opening an anonymous temporary file.
=back
+
=head1 Platform Specific Changes
+Perl is incredibly portable. In general, if a platform has a C compiler,
+someone has ported Perl to it (or will soon). We're happy to announce
+that Perl 5.12 includes support for several new platforms. At the same
+time, it's time to bid farewell to some (very) old friends.
+
=head2 New Platforms
=over
=item Haiku
-Patches from the Haiku maintainers have been merged in. Perl should now
-build on Haiku.
+Perl's developers have merged patches from Haiku's maintainers. Perl
+should now build on Haiku.
=item MirOS BSD
Perl should now build on MirOS BSD.
-
=back
=head2 Discontinued Platforms
=over
-=item DomainOS
+=item Domain/OS
-Support for Apollo DomainOS was removed in Perl 5.11.0
+=item MiNT
-=item MachTen
+=item Tenon MachTen
-Support for Tenon Intersystems MachTen Unix layer for MacOS Classic was
-removed in Perl 5.11.0
+=back
-=item MiNT
+=head2 Updated Platforms
+
+=over 4
+
+=item AIX
+
+=over 4
+
+=item *
+
+Removed F<libbsd> for AIX 5L and 6.1. Only C<flock()> was used from
+F<libbsd>.
+
+=item *
-Support for Atari MiNT was removed in Perl 5.11.0.
+Removed F<libgdbm> for AIX 5L and 6.1 if F<libgdbm> < 1.8.3-5 is
+installed. The F<libgdbm> is delivered as an optional package with the
+AIX Toolbox. Unfortunately the versions below 1.8.3-5 are broken.
+
+=item *
+
+Hints changes mean that AIX 4.2 should work again.
=back
-=head2 Updated Platforms
+=item Cygwin
=over 4
+=item *
+
+Perl now supports IPv6 on Cygwin 1.7 and newer.
+
+=item *
+
+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.
+
+=back
+
=item Darwin (Mac OS X)
=over 4
=back
-=item Win32
+=item FreeBSD
=over 4
=item *
-Initial support for mingw64 is now available
-
-=item *
-
-Various bits of Perl's build infrastructure are no longer converted to
-win32 line endings at release time. If this hurts you, please report the
-problem with the L<perlbug> program included with perl.
-
-=item *
+The hints files now identify the correct threading libraries on FreeBSD 7
+and later.
-Always add a manifest resource to C<perl.exe> to specify the C<trustInfo>
-settings for Windows Vista and later. Without this setting Windows
-will treat C<perl.exe> as a legacy application and apply various
-heuristics like redirecting access to protected file system areas
-(like the "Program Files" folder) to the users "VirtualStore"
-instead of generating a proper "permission denied" error.
+=back
-For VC8 and VC9 this manifest setting is automatically generated by
-the compiler/linker (together with the binding information for their
-respective runtime libraries); for all other compilers we need to
-embed the manifest resource explicitly in the external resource file.
+=item Irix
-This change also requests the Microsoft Common-Controls version 6.0
-(themed controls introduced in Windows XP) via the dependency list
-in the assembly manifest. For VC8 and VC9 this is specified using the
-C</manifestdependency> linker commandline option instead.
+=over 4
=item *
-Improved message window handling means that C<alarm> and C<kill> messages
-will no longer be dropped under race conditions.
+We now work around a bizarre preprocessor bug in the Irix 6.5 compiler:
+C<cc -E -> unfortunately goes into K&R mode, but C<cc -E file.c> doesn't.
=back
-=item cygwin
+=item NetBSD
=over 4
=item *
-Enable IPv6 support on cygwin 1.7 and newer
+Hints now supports versions 5.*.
=back
=item *
-Make -UDEBUGGING the default on VMS for 5.12.0.
+C<-UDEBUGGING> is now the default on VMS.
-Like it has been everywhere else for ages and ages. Also make
-command-line selection of -UDEBUGGING and -DDEBUGGING work in
-configure.com; before the only way to turn it off was by saying
-no in answer to the interactive question.
+Like it has been everywhere else for ages and ages. Also make command-line
+selection of -UDEBUGGING and -DDEBUGGING work in configure.com; before
+the only way to turn it off was by saying no in answer to the interactive
+question.
=item *
Enabling the C<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
+shell and other utilities that depend on POSIX exit values. See
L<perlvms/"$?"> for details.
=item *
=back
-=item AIX
+=item Stratus VOS
-Removed F<libbsd> for AIX 5L and 6.1. Only C<flock()> was used from F<libbsd>.
+=over 4
-Removed F<libgdbm> for AIX 5L and 6.1. The F<libgdbm> is delivered as an
-optional package with the AIX Toolbox. Unfortunately the 64 bit version
-is broken.
+=item *
-Hints changes mean that AIX 4.2 should work again.
+Various changes from Stratus have been merged in.
-=item Cygwin
+=back
-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.
+=item Symbian
+=over 4
-=item FreeBSD
+=item *
-The hints files now identify the correct threading libraries on FreeBSD 7
-and later.
+There is now support for Symbian S60 3.2 SDK and S60 5.0 SDK.
-=item Irix
+=back
-We now work around a bizarre preprocessor bug in the Irix 6.5 compiler:
-C<cc -E -> unfortunately goes into K&R mode, but C<cc -E file.c> doesn't.
+=item Windows
-=item NetBSD
+=over 4
-Hints now supports versions 5.*.
+=item *
-=item Stratus VOS
+Perl 5.12 supports Windows 2000 and later. The supporting code for
+legacy versions of Windows is still included, but will be removed
+during the next development cycle.
-Various changes from Stratus have been merged in.
+=item *
-=item Symbian
+Initial support for building Perl with MinGW-w64 is now available.
-There is now support for Symbian S60 3.2 SDK and S60 5.0 SDK.
+=item *
+
+F<perl.exe> now includes a manifest resource to specify the C<trustInfo>
+settings for Windows Vista and later. Without this setting Windows
+would treat F<perl.exe> as a legacy application and apply various
+heuristics like redirecting access to protected file system areas
+(like the "Program Files" folder) to the users "VirtualStore"
+instead of generating a proper "permission denied" error.
+
+The manifest resource also requests the Microsoft Common-Controls
+version 6.0 (themed controls introduced in Windows XP). Check out the
+Win32::VisualStyles module on CPAN to switch back to old style
+unthemed controls for legacy applications.
+
+=item *
+
+The C<-t> filetest operator now only returns true if the filehandle
+is connected to a console window. In previous versions of Perl it
+would return true for all character mode devices, including F<NUL>
+and F<LPT1>.
+
+=item *
+
+The C<-p> filetest operator now works correctly, and the
+Fcntl::S_IFIFO constant is defined when Perl is compiled with
+Microsoft Visual C. In previous Perl versions C<-p> always
+returned a false value, and the Fcntl::S_IFIFO constant
+was not defined.
+
+This bug is specific to Microsoft Visual C and never affected
+Perl binaries built with MinGW.
+
+=item *
+
+The socket error codes are now more widely supported: The POSIX
+module will define the symbolic names, like POSIX::EWOULDBLOCK,
+and stringification of socket error codes in $! works as well
+now;
+
+ C:\>perl -MPOSIX -E "$!=POSIX::EWOULDBLOCK; say $!"
+ A non-blocking socket operation could not be completed immediately.
+
+=item *
+
+flock() will now set sensible error codes in $!. Previous Perl versions
+copied the value of $^E into $!, which caused much confusion.
+
+=item *
+
+select() now supports all empty C<fd_set>s more correctly.
+
+=item *
+
+C<'.\foo'> and C<'..\foo'> were treated differently than
+C<'./foo'> and C<'../foo'> by C<do> and C<require> [RT #63492].
+
+=item *
+
+Improved message window handling means that C<alarm> and C<kill> messages
+will no longer be dropped under race conditions.
+
+=item *
+
+Various bits of Perl's build infrastructure are no longer converted to
+win32 line endings at release time. If this hurts you, please report the
+problem with the L<perlbug> program included with perl.
+
+=back
=back
+
=head1 Known Problems
This is a list of some significant unfixed bugs, which are regressions
-from either 5.10.0 or 5.8.x.
+from either 5.10.x or 5.8.x.
=over 4
=item *
-The C<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/;
-
-=item *
-
Some regexes may run much more slowly when run in a child thread compared
with the thread the pattern was compiled into [RT #55600].
=item *
-Untriaged test crashes on Windows 2000
-
-Several porters have reported mysterious crashes when Perl's entire test suite is run after a build on certain Windows 2000 systems. When run by hand, the individual tests reportedly work fine.
+Things like C<"\N{LATIN SMALL LIGATURE FF}" =~ /\N{LATIN SMALL LETTER F}+/>
+will appear to hang as they get into a very long running loop [RT #72998].
=item *
-Known test failures on VMS
+Several porters have reported mysterious crashes when Perl's entire
+test suite is run after a build on certain Windows 2000 systems. When
+run by hand, the individual tests reportedly work fine.
+
+=back
+
+=head1 Errata
-Perl 5.11.1 fails a small set of core and CPAN tests as of this release.
-With luck, that'll be sorted out for 5.11.2
+=over
=item *
-Known test failures on VMS
+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 C</m> modifier and C<qr> resulted
+in a change of behaviour between 5.8.x and 5.10.0:
-Perl 5.11.2 fails a small set of core and CPAN tests as of this
-release. With luck, that'll be sorted out for 5.11.3.
+ # matches in 5.8.x, doesn't match in 5.10.0
+ $re = qr/^bar/; "foo\nbar" =~ /$re/m;
=back
=head1 Acknowledgements
Perl 5.12.0 represents approximately two years of development since
-Perl 5.10.0 and contains __ lines of changes across ___ files
-from __ authors and committers:
-
-XXX TODO LIST
+Perl 5.10.0 and contains over 750,000 lines of changes across over
+3,000 files from over 200 authors and committers.
+
+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 5.12.0:
+
+Aaron Crane, Abe Timmerman, Abhijit Menon-Sen, Abigail, Adam Russell,
+Adriano Ferreira, Ævar Arnfjörð Bjarmason, Alan Grover, Alexandr
+Ciornii, Alex Davies, Alex Vandiver, Andreas Koenig, Andrew Rodland,
+andrew@sundale.net, Andy Armstrong, Andy Dougherty, Jose AUGUSTE-ETIENNE,
+Benjamin Smith, Ben Morrow, bharanee rathna, Bo Borgerson, Bo Lindbergh,
+Brad Gilbert, Bram, Brendan O'Dea, brian d foy, Charles Bailey,
+Chip Salzenberg, Chris 'BinGOs' Williams, Christoph Lamprecht, Chris
+Williams, chromatic, Claes Jakobsson, Craig A. Berry, Dan Dascalescu,
+Daniel Frederick Crisman, Daniel M. Quinlan, Dan Jacobson, Dan Kogai,
+Dave Mitchell, Dave Rolsky, David Cantrell, David Dick, David Golden,
+David Mitchell, David M. Syzdek, David Nicol, David Wheeler, Dennis
+Kaarsemaker, Dintelmann, Peter, Dominic Dunlop, Dr.Ruud, Duke Leto,
+Enrico Sorcinelli, Eric Brine, Father Chrysostomos, Florian Ragwitz,
+Frank Wiegand, Gabor Szabo, Gene Sullivan, Geoffrey T. Dairiki, George
+Greer, Gerard Goossen, Gisle Aas, Goro Fuji, Graham Barr, Green, Paul,
+Hans Dieter Pearcey, Harmen, H. Merijn Brand, Hugo van der Sanden,
+Ian Goodacre, Igor Sutton, Ingo Weinhold, James Bence, James Mastros,
+Jan Dubois, Jari Aalto, Jarkko Hietaniemi, Jay Hannah, Jerry Hedden,
+Jesse Vincent, Jim Cromie, Jody Belka, John E. Malmberg, John Malmberg,
+John Peacock, John Peacock via RT, John P. Linderman, John Wright,
+Josh ben Jore, Jos I. Boumans, Karl Williamson, Kenichi Ishigaki, Ken
+Williams, Kevin Brintnall, Kevin Ryde, Kurt Starsinic, Leon Brocard,
+Lubomir Rintel, Luke Ross, Marcel Grünauer, Marcus Holland-Moritz, Mark
+Jason Dominus, Marko Asplund, Martin Hasch, Mashrab Kuvatov, Matt Kraai,
+Matt S Trout, Max Maischein, Michael Breen, Michael Cartmell, Michael
+G Schwern, Michael Witten, Mike Giroux, Milosz Tanski, Moritz Lenz,
+Nicholas Clark, Nick Cleaton, Niko Tyni, Offer Kaye, Osvaldo Villalon,
+Paul Fenwick, Paul Gaborit, Paul Green, Paul Johnson, Paul Marquess,
+Philip Hazel, Philippe Bruhat, Rafael Garcia-Suarez, Rainer Tammer,
+Rajesh Mandalemula, Reini Urban, Renée Bäcker, Ricardo Signes,
+Ricardo SIGNES, Richard Foley, Rich Rauenzahn, Rick Delaney, Risto
+Kankkunen, Robert May, Roberto C. Sanchez, Robin Barker, SADAHIRO
+Tomoyuki, Salvador Ortiz Garcia, Sam Vilain, Scott Lanning, Sébastien
+Aperghis-Tramoni, Sérgio Durigan Júnior, Shlomi Fish, Simon 'corecode'
+Schubert, Sisyphus, Slaven Rezic, Smylers, Steffen Müller, Steffen
+Ullrich, Stepan Kasal, Steve Hay, Steven Schubiger, Steve Peters, Tels,
+The Doctor, Tim Bunce, Tim Jenness, Todd Rinaldo, Tom Christiansen,
+Tom Hukins, Tom Wyant, Tony Cook, Torsten Schoenfeld, Tye McQueen,
+Vadim Konovalov, Vincent Pit, Hio YAMASHINA, Yasuhiro Matsumoto,
+Yitzchak Scott-Thoennes, Yuval Kogman, Yves Orton, Zefram, Zsban Ambrus
+
+This is woefully incomplete as it's automatically generated from version
+control history. In particular, it doesn't include the names of the
+(very much appreciated) contributors who reported issues in previous
+versions of Perl that helped make Perl 5.12.0 better. For a more complete
+list of all of Perl's historical contributors, please see the C<AUTHORS>
+file in the Perl 5.12.0 distribution.
+
+Our "retired" pumpkings Nicholas Clark and Rafael Garcia-Suarez
+deserve special thanks for their brilliant and substantive ongoing
+contributions. Nicholas personally authored over 30% of the patches
+since 5.10.0. Rafael comes in second in patch authorship with 11%,
+but is first by a long shot in committing patches authored by others,
+pushing 44% of the commits since 5.10.0 in this category, often after
+providing considerable coaching to the patch authors. These statistics
+in no way comprise all of their contributions, but express in shorthand
+that we couldn't have done it without them.
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
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 L<http://rt.perl.org/perlbug/>. There may also be
+bug database at L<http://rt.perl.org/perlbug/>. There may also be
information at L<http://www.perl.org/>, the Perl Home Page.
If you believe you have an unreported bug, please run the B<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
+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 C<perl -V>, will be sent off to perlbug@perl.org to be
analyzed by the Perl porting team.
The F<Artistic> and F<Copying> files for copyright information.
+L<http://dev.perl.org/perl5/errata.html> for a list of issues
+found after this release, as well as a list of CPAN modules known
+to be incompatible with this release.
+
=cut
https://perl5.git.perl.org / perl5.git / blobdiff