perl5120delta - what is new for perl v5.12.0
-=head1 XXX - THIS DOCUMENT IS ONLY CURRENT THROUGH PERL5115
-
FIX ME BEFORE RELEASE
-OTHER ISSUES:
-
UPDATED MODULE LIST NEEDS TO BE GENERATED
-ORDERING NEEDS CHECKING
-HEAVY COPYEDITING IS NEEDED
-
=head1 DESCRIPTION
You can see the list of those changes in the 5.10.1 release notes (L<perl5101delta>).
-=head1 New features and New syntax
+=head1 Core Enhancements
=head2 New C<package NAME VERSION> syntax
use strict;
use feature ':5.12';
+=head2 Unicode improvements
-=head1 Core Enhancements
+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
mechanism, so extensions could only properly influence subroutine names
that appeared with an C<&> sigil.)
-=head2 Unicode version 5.2
-
-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.
-
-=head2 Overhaul of Unicode property support
-
-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>.
-
-=head2 Regular Expressions
-
-U+0FFFF is now a legal character in regular expressions.
-
=head2 A proper interface for pluggable Method Resolution Orders
As of Perl 5.12.0 there is a new interface for plugging and using method
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 \N{...} now compiles better, always forces UTF-8 internal representation.
-
-There were several problems that have been fixed with recognizing C<\N{...}>
-constructs. As part of this, any scalar or regex that has either a
-C<\N{I<name>}> or C<\N{U+I<wide hex char>}> in its definition will be stored 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.)
=head2 C<\N> experimental regex escape
The C<each> function can now operate on arrays.
-=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 C<$,> flexibility
The variable C<$,> may now be tied.
of the system's signed and unsigned integers is now available for the C<pos>
and C<len> arguments.
-=head1 Incompatible Changes
+=head1 Potentially Incompatible Changes
=head2 Deprecations warn by default
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<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
=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 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">.
# 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
The definitions of a number of Unicode properties have changed to match
those of the current Unicode standard. These are listed above under
-L</Overhaul of Unicode property support>. This could break code that
-is expecting the old definitions.
+L</Unicode overhaul>. This change may break code that expects the old definitions.
=item *
-The boolkeys op moved to the group of hash ops. This breaks binary
+The boolkeys op has moved to the group of hash ops. This breaks binary
compatibility.
=item *
=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 *
=back
+
=head1 Deprecations
From time to time, Perl's developers find it necessary to deprecate
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 4
+=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 is now deprecated.
+
+=item Use of C<:=> to mean an empty attribute list
An accident of Perl's parser meant that these constructions were all
equivalent:
pass import arguments to a C<use UNIVERSAL> statement will result in a
deprecation warning.
-=item Use of "goto" to jump into a construct is deprecated
+
+=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} should look like names
+=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
=item L<Switch>
-Switch is buggy and should be avoided. See L<perlsyn/"Switch
-statements"> for its replacement.
+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 suidperl
-
-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 Assignment to $[
-=item attrs
+=item Use of the attribute :locked on subroutines
-Remove attrs, which has been deprecated since 1999-10-02.
+=item Use of "locked" with the attributes pragma
-=item Use of the attribute :locked on subroutines.
+=item Use of "unique" with the attributes pragma
-=item Use of "locked" with the attributes pragma.
+=item Perl_pmflag
-=item Use of "unique" with the attributes pragma.
+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:
+=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<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 Modules and Pragmata
+=head1 Unicode overhaul
-=head2 Dual-lifed modules moved
+Perl's developers have made a concerted effort to update Perl to be in
+sync with the latest Unicode standard. Changes for this include:
-Dual-lifed modules maintained primarily in the Perl core now live in dist/.
-Dual-lifed modules maintained primarily on CPAN now live in cpan/
+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.
-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>.
+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).
-=head2 New Modules and Pragmata
+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.
-=over 4
+Perl now accepts all the Unicode-defined synonyms for properties and property values.
-=item *
+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:
-C<autodie>
+=over
-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<\X> will not break apart a C<S<CR LF>> sequence.
=item *
-C<Compress::Raw::Bzip2>
+C<\X> will now match a sequence which includes the C<ZWJ> and C<ZWNJ> characters.
+
+=item *
-This has been added to the core (version 2.020).
+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<parent>
+C<\X> will now match a (Korean) Hangul syllable sequence, and the Thai and Lao
+exception cases.
-This pragma establishes an ISA relationship with base classes at compile
-time. It provides the key feature of C<base> without further unwanted
-behaviors.
+=back
-=item *
+Otherwise, this change should be transparent for the non-affected languages.
-C<Parse::CPAN::Meta>
+C<\p{...}> matches using the Canonical_Combining_Class property were
+completely broken in previous releases of Perl. They should now work correctly.
-This has been added to the core (version 1.39).
+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.
-=back
+C<\p{Decomposition_Type=Canonical}> now includes the Hangul syllables.
-=head2 Pragmata Changes
+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.
-=over 4
+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.
-=item *
+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<overloading>
+C<\p{Word}> no longer incorrectly matches non-word characters such as fractions.
-See L</"The C<overloading> pragma"> above.
+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.
-=item *
+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.
-C<attrs>
+The Numeric type property has been extended to include the Unihan
+characters.
-The C<attrs> pragma has been removed. It had been marked as deprecated since
-5.6.0.
+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.
-=item *
+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.
-C<charnames>
+The Default_Ignorable_Code_Point, ID_Continue, and ID_Start properties
+are now up to date with current Unicode definitions.
-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}">.
+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.
-=item *
+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.
-C<feature>
+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>.
-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<mro>
+=head1 Modules and Pragmata
-Upgraded from version 1.00 to 1.01. Performance for single inheritance is 40%
-faster - see L</"Performance Enhancements"> below.
+=head2 Notable new Modules and Pragmata
-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".
+=over 4
=item *
-C<diagnostics>
+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.
+
+=item *
-Supports %.0f formatting internally.
+C<Compress::Raw::Bzip2>
=item *
-C<overload>
+C<overloading> allows you to lexically disable or enable overloading
+for some or all operations. (Yuval Kogman)
-Allow overloading of 'qr'.
+=item *
+
+C<parent> establishes an ISA relationship with base classes at compile
+time. It provides the key feature of C<base> without further unwanted
+behaviors.
=item *
-C<constant>
+C<Parse::CPAN::Meta>
-Upgraded from version 1.19 to 1.20.
+=back
-=item *
+=head2 Notable changes to Modules and Pragmata
-C<diagnostics>
+=over 4
-This pragma no longer suppresses C<Use of uninitialized value in range
-(or flip)> warnings. [perl #71204]
+=item *
+
+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}">.
=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.
-Upgraded from 1.13 to 1.14. Added the C<unicode_strings> feature:
+C<feature> now includes the C<unicode_strings> feature:
use feature "unicode_strings";
=item *
-C<threads>
-
-Upgraded from version 1.74 to 1.75.
+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<less>
+C<diagnostics> now supports %.0f formatting internally.
-Upgraded from version 0.02 to 0.03.
+=item *
-This version introduces the C<stash_name> method to allow subclasses of
-C<less> to pick where in %^H to store their stash.
+C<overload> now allow overloading of 'qr'.
=item *
-C<version>
-
-Upgraded from version 0.77 to 0.81.
+C<diagnostics> no longer suppresses C<Use of uninitialized value in range
+(or flip)> warnings. [perl #71204]
-This version adds support for L</Version number formats> as described earlier
-in this document and in its own documentation.
+C<less> now includes the C<stash_name> method to allow subclasses of
+C<less> to pick where in %^H to store their stash.
=item *
-C<warnings>
+C<version> now has support for L</Version number formats> as described earlier
+in this document and in its own documentation.
-Upgraded from 1.07 to 1.09.
+=item *
-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.
+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.
=back
-=head2 Updated Modules
+=head2 Removed Modules and Pragmata
=over 4
-=item XXX TODO RECALCULATE THIS VS 5.10.0
-
-=back
+=item *
-=head2 Removed Modules and Pragmata
+C<attrs>
-=over 4
+The C<attrs> pragma has been removed. It had been marked as deprecated
+since 5.6.0.
=item *
-C<Devel::DProf::V>
-
-Removed from the Perl core. Prior version was 'undef'.
+C<Devel::DProf::V> is no longer part of the Perl core.
=back
+=head2 Deprecated Modules and Pragmata
+
+See L</Deprecated Modules> above.
+
=head1 Documentation
=head2 New 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
+L<perlrepository> describes how to access the perl source using the I<git> version
control system.
=item *
=head2 Changes to Existing Documentation
+
=over
=item *
-The file F<Porting/patching.pod> has been deleted, as it mainly described
+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>.
=item *
-Documented C<when> as a syntax modifier
+Documented C<when> as a syntax modifier.
=item *
=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.
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
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>.
=back
-=head1 Performance Enhancements
+=head1 Selected Performance Enhancements
=over 4
=item *
-Faster C<Perl_sv_utf8_upgrade()>
+C<Perl_sv_utf8_upgrade()> is now faster.
=item *
-Speed up C<keys> on empty hash
+C<keys> on empty hash is now faster.
=item *
-C<if (%foo)> has been optimized to be faster than C<if (keys %foo)>
+C<if (%foo)> has been optimized to be faster than C<if (keys %foo)>.
=item *
=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 Other Installation and Configuration Improvements
-
=over 4
=item *
=item *
-USE_ATTRIBUTES_FOR_PERLIO is now reported in the compile-time options
-listed by the C<-V> switch.
-
-=item *
-
-Support for SystemTap's C<dtrace> compatibility layer has been added and an
+Perl now supports SystemTap's C<dtrace> compatibility layer and an
issue with linking C<miniperl> has been fixed in the process.
=item *
-C<less -R> is now used instead of C<less> for C<groff>'s new usage of ANSI
-escape codes by setting C<$Config{less}> (and thereby C<$Config{pager}>,
-which fixes RT #72156.
+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 *
-USE_PERL_ATOF is now reported in the compile-time options listed by the C<-V>
-switch.
-
-=back
+C<perl -V> now reports use of the compile-time options C<USE_PERL_ATOF> and
+C<USE_ATTRIBUTES_FOR_PERLIO>.
-=head2 Compilation improvements
+=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
+
+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.
+
+=over
=item *
-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.
+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 *
-Perl_magic_setmglob now knows about globs, fixing RT #71254.
+The internal structure of the dual-life modules traditionally found in
+the F<lib/> and F<ext/> directories y 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: C<SVt_RV> is gone. RVs are now stored in IVs
+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: REGEXPs are first class
+Perl_magic_setmglob now knows about globs, fixing RT #71254.
=item *
-TODO: OOK is reworked, such that an OOKed scalar is PV not PVIV
+C<SVt_RV> no longer exists. RVs are now stored in IVs.
=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.
+REGEXPs are now first class.
=item *
=item *
-C<SVf_UTF8>
-
-This will call C<SvUTF8_on()> for you. (Note that this does not convert an
+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 *
=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.
Use of the private structure C<mro_meta> has changed slightly. Nothing
outside the core should be accessing this directly anyway.
-=item *
+=item *
+
+A new tool, F<Porting/expand-macro.pl> has been added, that allows you
+to view how a C preprocessor macro would be expanded when compiled.
+This is handy when trying to decode the macro hell that is the perl
+guts.
+
+=back
+
+=head1 Testing
+
+=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
-A new tool, F<Porting/expand-macro.pl> has been added, that allows you
-to view how a C preprocessor macro would be expanded when compiled.
-This is handy when trying to decode the macro hell that is the perl
-guts.
+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.
-=back
+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.
-=head1 Testing
+=item Test harness flexibility
-=head2 New Tests
+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).
-Some core-specific tests have been added:
+
+=back
+
+=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/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
+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.
+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>
-
-See if C<< @{"_<$file"} >> works
+F<t/comp/line_debug.t> tests whether C<< @{"_<$file"} >> works.
=item *
-F<t/op/filetest_t.t>
-
-See if -t file test works
+F<t/op/filetest_t.t> tests if -t file test works.
=item *
-F<t/op/qr.t>
-
-See if qr works
+F<t/op/qr.t> tests C<qr>.
=item *
-F<t/op/utf8cache.t>
-
-Tests malfunctions of utf8 cache
+F<t/op/utf8cache.t> tests malfunctions of the utf8 cache.
=item *
-F<t/re/uniprops.t>
-
-Test unicode \p{} regex constructs
+F<t/re/uniprops.t> test unicodes C<\p{}> regex constructs.
=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.
+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/time_loop.t>
-
-Tests that 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.
+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.
=back
-=head2 Testing improvements
-
-=over 4
-=item Parallel tests
+=head1 New or Changed Diagnostics
-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
+=head2 New Diagnostics
- TEST_JOBS=3 make test_harness # Run 3 tests in parallel
+=over
-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.
+=item *
-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.
+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 Test harness flexibility
+=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>
-
-The two warnings :
-
- Illegal character in prototype for %s : %s
- Prototype after '%c' for %s : %s
-
-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
-
- 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. (Matt S. Trout)
-
-=item *
-
-lvalue attribute ignored after the subroutine has been defined
+C<lvalue attribute ignored after the subroutine has been defined>
This new warning is issued when one attempts to mark a subroutine as
lvalue after it has been defined.
=item *
-warn if C<++> or C<--> are unable to change the value because it's
-beyond the limit of representation
+Perl now warns you if C<++> or C<--> are unable to change the value because it's
+beyond the limit of representation.
This uses a new warnings category: "imprecision".
=item *
-Show constant in "Useless use of a constant in void context"
+C<Show constant in "Useless use of a constant in void context">
=item *
-Make the new warning report undef constants as undef
+C<Prototype after '%s'>
=item *
-Add a new warning, "Prototype after '%s'"
+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.
+
=item *
-Tweak the "Illegal character in prototype" warning so it's more precise
-when reporting illegal characters after _
+The fatal error C<Malformed UTF-8 returned by \N> is now produced if the
+C<charnames> handler returns malformed UTF-8.
=item *
-Correct the unintended interpolation of C<$\> in regex
+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}'; $re;>. See L<perldiag> for more examples of
+how the lexer can get bypassed.
=item *
-Make overflow warnings in C<gmtime> and C<localtime> only occur when
-warnings are enabled
+C<Invalid hexadecimal number in \\N{U+...}> is a new fatal error triggered when
+the character constant represented by C<...> is not a valid hexadecimal
+number.
=item *
-Improve mro merging error messages.
+The new meaning of C<\N> as C<[^\n]> is not valid in a bracketed character
+class, just like C<.> in a character class loses its special meaning, and will
+cause the fatal error C<\\N in a character class must be a named character: \\N{...}>.
+
+=item *
-They are now very similar to those produced by Algorithm::C3.
+The rules on what is legal for the C<...> in C<\N{...}> have been tightened
+up so that unless the C<...> begins with an alphabetic character and continues
+with a combination of alphanumerics, dashes, spaces, parentheses or colons
+then the warning C<Deprecated character(s) in \\N{...} starting at '%s'> is
+now issued.
=item *
-Amelioration of the error message "Unrecognized character %s in column %d"
+The warning C<Using just the first characters returned by \N{}> will be
+issued if the C<charnames> handler returns a sequence of characters which
+exceeds the limit of the number of characters that can be used. The message
+will indicate which characters were used and which were discarded.
-Changes the error message to "Unrecognized character %s; marked by E<lt>--
-HERE after %sE<lt>-- HERE near column %d". This should make it a little
-simpler to spot and correct the suspicious character.
+=back
-=item *
+=back
-Explicitely point to C<$.> when it causes an uninitialized warning for
-ranges in scalar context
+=head2 Changed Diagnostics
-=item *
+A number of existing diagnostic messages have been improved or corrected:
-C<split> now warns when called in void context
+=over
=item *
-C<printf>-style functions called with too few arguments will now issue the
-warning C<"Missing argument in %s"> [perl #71000]
+A new warning category C<illegalproto> allows finer-grained control of
+warnings around function prototypes.
-=item *
+The two warnings:
-C<panic: sv_chop %s>
+=over
-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.
+=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 do
+
+ 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. (Matt S. Trout)
=item *
=item *
-Perl now properly returns a syntax error instead of segfaulting
-if C<each>, C<keys>, or C<values> is used without an argument.
+C<Illegal character in prototype> warning is now more precise
+when reporting illegal characters after _
=item *
-C<tell()> now fails properly if called without an argument and when no
-previous file was read.
-
-C<tell()> now returns C<-1>, and sets errno to C<EBADF>, thus restoring
-the 5.8.x behaviour.
+mro merging error messages are now very similar to those produced by L<Algorithm::C3>.
=item *
-C<overload> no longer implicitly unsets fallback on repeated 'use
-overload' lines.
+Amelioration of the error message "Unrecognized character %s in column %d"
+
+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 *
-POSIX::strftime() can now handle Unicode characters in the format string.
+Perl now explicitly points to C<$.> when it causes an uninitialized warning for
+ranges in scalar context.
=item *
-The Windows select() implementation now supports all empty C<fd_set>s
-more correctly.
+C<split> now warns when called in void context.
=item *
-The "syntax" category was removed from 5 warnings that should only be in
-"deprecated".
+C<printf>-style functions called with too few arguments will now issue the
+warning C<"Missing argument in %s"> [perl #71000]
=item *
-Three fatal C<pack>/C<unpack> error messages have been normalized to
-"panic: %s"
+Perl now properly returns a syntax error instead of segfaulting
+if C<each>, C<keys>, or C<values> is used without an argument.
=item *
-"Unicode character is illegal" has been rephrased to be more accurate
+C<tell()> now fails properly if called without an argument and when no
+previous file was read.
-It now reads C<Unicode non-character is illegal in interchange> and the
-perldiag documentation has been expanded a bit.
+C<tell()> now returns C<-1>, and sets errno to C<EBADF>, thus restoring
+the 5.8.x behaviour.
=item *
-The fatal error C<Malformed UTF-8 returned by \N> is now produced if the
-C<charnames> handler returns malformed UTF-8.
+C<overload> no longer implicitly unsets fallback on repeated 'use
+overload' lines.
=item *
-If an unresolved named character or sequence was encountered when compiling a
-regex pattern then the fatal error C<\\N{NAME} must be resolved by the lexer>
-is now produced. This can happen, for example, when using a single-quotish
-context like C<$re = '\N{SPACE}'; $re;>. See L<perldiag> for more examples of
-how the lexer can get bypassed.
+POSIX::strftime() can now handle Unicode characters in the format string.
=item *
-The fatal error C<Invalid hexadecimal number in \\N{U+...}> will be produced
-if the character constant represented by C<...> is not a valid hexadecimal
-number.
+The Windows select() implementation now supports all empty C<fd_set>s
+more correctly.
=item *
-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{...}>.
+The C<syntax> category was removed from 5 warnings that should only be in
+C<deprecated>.
=item *
-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.
+Three fatal C<pack>/C<unpack> error messages have been normalized to
+C<panic: %s>
=item *
-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.
+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 *
=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
+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
+F<h2xs> no longer incorrectly treats enum values like macros (Daniel Burr).
+It also now handles C++ style constants (C<//>) properly in enums. (A patch from
Rainer Weikusat was used; Daniel Burr also proposed a similar fix).
=item *
-F<perl5db.pl>
-
-C<LVALUE> subroutines now work under the debugger.
-
-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.
+F<perl5db.pl> now supports C<LVALUE> subroutines. Additionally, the debugger now correctly handles proxy constant subroutines, and subroutine stubs.
=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 ithe 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.
=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
=item *
-Previously missing files from Unicode 5.1 Character Database are now included.
+Perl now includes previously missing files from the Unicode 5.1 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
+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
-Support for Apollo DomainOS was removed in Perl 5.11.0
-
-=item MachTen
-
-Support for Tenon Intersystems MachTen Unix layer for MacOS Classic was
-removed in Perl 5.11.0
+=item Tenon MachTen
=item MiNT
-Support for Atari MiNT was removed in Perl 5.11.0.
-
=back
=head2 Updated Platforms
=item *
-Initial support for mingw64 is now available
+Initial support for mingw64 is now available.
=item *
=item *
-Enable IPv6 support on cygwin 1.7 and newer
+Perl now suppoorts IPv6 on cygwin 1.7 and newer.
=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
=back
+
=head1 Known Problems
This is a list of some significant unfixed bugs, which are regressions
=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.
+=back
+
+=head1 Errata
+
+=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 5.11.1 fails a small set of core and CPAN tests as of this release.
-With luck, that'll be sorted out for 5.11.2
+ # matches in 5.8.x, doesn't match in 5.10.0
+ $re = qr/^bar/; "foo\nbar" =~ /$re/m;
=back
projects / p5sagit/p5-mst-13.2.git / commitdiff