This document describes differences between the 5.12.0 release and
the 5.14.0 release.
+If you are upgrading from an earlier release such as 5.10.0, first read
+L<perl5120delta>, which describes differences between 5.10.0 and
+5.12.0.
+
Some of the bug fixes in this release have been backported to subsequent
releases of 5.12.x. Those are indicated with the 5.12.x version in
parentheses.
-XXX Go through the perl512*delta files and do that.
-
=head1 Notice
XXX Any important notices here
with one exception noted below.
See L<http://unicode.org/versions/Unicode6.0.0> for details on the new
release. Perl does not support any Unicode provisional properties,
-including the new ones for this release, but their database files are
-packaged with Perl.
+including the new ones for this release.
Unicode 6.0 has chosen to use the name C<BELL> for the character at U+1F514,
-which is a symbol that looks like a bell, and used in Japanese cell
+which is a symbol that looks like a bell, and is used in Japanese cell
phones. This conflicts with the long-standing Perl usage of having
C<BELL> mean the ASCII C<BEL> character, U+0007. In Perl 5.14,
C<\N{BELL}> will continue to mean U+0007, but its use will generate a
=item *
C<\N{}> and C<charnames::vianame> now know about the abbreviated
-character names listed by Unicode, such as NBSP, SHY, LRO, ZWJ, etc., as
-well as all the customary abbreviations for the C0 and C1 control
-characters (such as ACK, BEL, CAN, etc.), as well as a few new variants
-in common usage of some C1 full names.
+character names listed by Unicode, such as NBSP, SHY, LRO, ZWJ, etc., all
+the customary abbreviations for the C0 and C1 control characters (such as
+ACK, BEL, CAN, etc.), and a few new variants of some C1 full names that
+are in common usage.
=item *
=item *
-You can also create a custom alias directly to the ordinal of a
+You can also create a custom alias of the ordinal of a
character, known by C<\N{...}>, C<charnames::vianame()>, and
C<charnames::viacode()>. Previously, an alias had to be to an official
Unicode character name. This made it impossible to create an alias for
-a code point that had no name, such as the ones reserved for private
-use. So this change allows you to make more effective use of private
-use characters. Only if there is no official name will
-C<charnames::viacode()> return your custom one.
+a code point that had no name, such as those reserved for private
+use.
=item *
See L<charnames> for details on all these changes.
+=head3 New warnings categories for problematic (non-)Unicode code points.
+
+Three new warnings subcategories of "utf8" have been added. These
+allow you to turn off some "utf8" warnings, while allowing
+others warnings to remain on. The three categories are:
+C<surrogate> when UTF-16 surrogates are encountered;
+C<nonchar> when Unicode non-character code points are encountered;
+and C<non_unicode> when code points that are above the legal Unicode
+maximum of 0x10FFFF are encountered.
+
=head3 Any unsigned value can be encoded as a character
With this release, Perl is adopting a model that any unsigned value can
be treated as a code point and encoded internally (as utf8) without
-warnings -- not just the code points that are legal in Unicode.
-However, unless utf8 warnings have been
+warnings - not just the code points that are legal in Unicode.
+However, unless utf8 or the corresponding sub-category (see previous
+item) warnings have been
explicitly lexically turned off, outputting or performing a
Unicode-defined operation (such as upper-casing) on such a code point
will generate a warning. Attempting to input these using strict rules
them will work the same as for the non-legal Unicode code points, as the
Unicode standard says they are illegal for "open interchange".
-=head3 New warnings categories for problematic (non-)Unicode code points.
+=head3 Unicode database files not installed
-Three new warnings subcategories of <utf8> have been added. These
-allow you to turn off warnings for their covered events, while allowing
-the other UTF-8 warnings to remain on. The three categories are:
-C<surrogate> when UTF-16 surrogates are encountered;
-C<nonchar> when Unicode non-character code points are encountered;
-and C<non_unicode> when code points that are above the legal Unicode
-maximum of 0x10FFFF are encountered.
+The Unicode database files are no longer installed with Perl. This
+doesn't affect any functionality in Perl and saves significant disk
+space. If you previously were explicitly opening and reading those
+files, you can download them from
+L<http://www.unicode.org/Public/zipped/6.0.0/>.
=head2 Regular Expressions
=head3 C<(?^...)> construct to signify default modifiers
-A caret (also called a "circumflex accent") C<"^"> immediately following
-a C<"(?"> in a regular expression now means that the subexpression is to
-not inherit the surrounding modifiers such as C</i>, but to revert to the
+An ASCII caret (also called a "circumflex accent") C<"^">
+immediately following a C<"(?"> in a regular expression
+now means that the subexpression does not inherit the
+surrounding modifiers such as C</i>, but reverts to the
Perl defaults. Any modifiers following the caret override the defaults.
The stringification of regular expressions now uses this
C<(?i-xsm:hlagh)>, but now it's stringified as C<(?^i:hlagh)>.
The main purpose of this is to allow tests that rely on the
-stringification to not have to change when new modifiers are added.
+stringification not to have to change when new modifiers are added.
See L<perlre/Extended Patterns>.
=head3 C</d>, C</l>, C</u>, C</a>, and C</aa> modifiers
The C</u> modifier says to compile the regular expression as if it were
in the scope of a C<use feature "unicode_strings"> pragma.
-The C</d> modifier is used to override any C<use locale> and
+The C</d> (default) modifier is used to override any C<use locale> and
C<use feature "unicode_strings"> pragmas that are in effect at the time
of compiling the regular expression.
The C</a> regular expression modifier restricts C<\s>, C<\d> and C<\w> and
-the Posix (C<[[:posix:]]>) character classes to the ASCII range. The
+the Posix (C<[[:posix:]]>) character classes to the ASCII range. Their
complements and C<\b> and C<\B> are correspondingly
affected. Otherwise, C</a> behaves like the C</u> modifier, in that
-case-insensitive matching uses Unicode semantics; for example, "k" will
-match the Unicode C<\N{KELVIN SIGN}> under C</i> matching, and code
-points in the Latin1 range, above ASCII will have Unicode semantics when
-it comes to case-insensitive matching.
+case-insensitive matching uses Unicode semantics.
The C</aa> modifier is like C</a>, except that, in case-insensitive matching, no ASCII character will match a
non-ASCII character. For example,
C<(??{...})> code blocks inside regular expressions.
These block are still experimental, however, and still have problems with
-lexical (C<my>) variables, lexical pragmata and abnormal exiting.
+lexical (C<my>) variables and abnormal exiting.
=head3 C<use re '/flags';>
=head3 \o{...} for octals
-There is a new escape sequence, C<"\o">, in double-quote-like contexts.
-It must be followed by braces enclosing an octal number of at least one
-digit. It interpolates as the character with an ordinal value equal to
-the octal number. This construct allows large octal ordinals beyond the
+There is a new octal escape sequence, C<"\o">, in double-quote-like
+contexts. This construct allows large octal ordinals beyond the
current max of 0777 to be represented. It also allows you to specify a
character in octal which can safely be concatenated with other regex
snippets and which won't be confused with being a backreference to
Regular expression debugging output (turned on by C<use re 'debug';>) now
uses hexadecimal when escaping non-ASCII characters, instead of octal.
+=head3 Return value of C<delete $+{...}>
+
+Custom regular expression engines can now determine the return value of
+C<delete> on an entry of C<%+> or C<%->.
+
=head2 Syntactical Enhancements
=head3 Array and hash container functions accept references
For C<push>, C<unshift> and C<splice>, the reference will auto-vivify
if it is not defined, just as if it were wrapped with C<@{}>.
-Calling C<keys> or C<values> directly on a reference gives a substantial
-performance improvement over explicit dereferencing.
-
For C<keys>, C<values>, C<each>, when overloaded dereferencing is
present, the overloaded dereference is used instead of dereferencing the
-underlying reftype. Warnings are issued about assumptions made in the
-following three ambiguous cases:
-
- (a) If both %{} and @{} overloading exists, %{} is used
- (b) If %{} overloading exists on a blessed arrayref, %{} is used
- (c) If @{} overloading exists on a blessed hashref, @{} is used
+underlying reftype. Warnings are issued about assumptions made in
+ambiguous cases.
=head3 Single term prototype
The C<+> prototype is a special alternative to C<$> that will act like
C<\[@%]> when given a literal array or hash variable, but will otherwise
-force scalar context on the argument. This is useful for functions which
-should accept either a literal array or an array reference as the argument:
-
- sub smartpush (+@) {
- my $aref = shift;
- die "Not an array or arrayref" unless ref $aref eq 'ARRAY';
- push @$aref, @_;
- }
-
-When using the C<+> prototype, your function must check that the argument
-is of an acceptable type.
+force scalar context on the argument. See L<perlsub/Prototypes>.
=head3 C<package> block syntax
declaration is in scope only inside that block. So C<package Foo { ... }>
is precisely equivalent to C<{ package Foo; ... }>. It also works with
a version number in the declaration, as in C<package Foo 1.2 { ... }>.
-See L<perlfunc> (434da3..36f77d, 702646).
+See L<perlfunc>.
=head3 Statement labels can appear in more places
Literals may now use either upper case C<0X...> or C<0B...> prefixes,
in addition to the already supported C<0x...> and C<0b...>
-syntax. (RT#76296) (a674e8d, 333f87f)
+syntax [perl #76296].
C, Ruby, Python and PHP already supported this syntax, and it makes
Perl more internally consistent. A round-trip with C<eval sprintf
-"%#X", 0x10> now returns C<16> in addition to C<eval sprintf "%#x",
-0x10>, which worked before.
+"%#X", 0x10> now returns C<16>, the way C<eval sprintf "%#x", 0x10> does.
+
+=head3 Overridable tie functions
+
+C<tie>, C<tied> and C<untie> can now be overridden [perl #75902].
=head2 Exception Handling
=head3 C<srand()> now returns the seed
-This allows programs that need to have repeatable results to not have to come
-up with their own seed generating mechanism. Instead, they can use C<srand()>
-and somehow stash the return for future use. Typical is a test program which
+This allows programs that need to have repeatable results not to have to come
+up with their own seed-generating mechanism. Instead, they can use C<srand()>
+and stash the return value for future use. Typical is a test program which
has too many combinations to test comprehensively in the time available to it
-each run. It can test a random subset each time, and should there be a failure,
+each run. It can test a random subset each time and, should there be a failure,
log the seed used for that run so that it can later be used to reproduce the
-exact results.
+same results.
=head3 printf-like functions understand post-1980 size modifiers
=back
-This is particularly useful to suppresses the default actions of a
+This is particularly useful for suppressing the default actions of a
C<Devel::*> module's C<import> method whilst still loading it for debugging.
=head3 Filehandle method calls load L<IO::File> on demand
open my $fh, ">", $file;
$fh->autoflush(1); # IO::File not loaded
+=head3 IPv6 support
+
+The C<Socket> module provides new affordances for IPv6,
+including implementations of the C<Socket::getaddrinfo()> and
+C<Socket::getnameinfo()> functions, along with related constants, and a
+handful of new functions. See L<Socket>.
+
=head3 DTrace probes now include package name
The DTrace probes now include an additional argument (C<arg3>) which contains
main::test
+=head2 New C APIs
+
+See L</Internal Changes>.
+
=head1 Security
-=head2 Restrict \p{IsUserDefined} to In\w+ and Is\w+
+=head2 User-defined regular expression properties
In L<perlunicode/"User-Defined Character Properties">, it says you can
create custom properties by defining subroutines whose names begin with
-"In" or "Is". However, perl doesn't actually enforce that naming
-restriction, so \p{foo::bar} will call foo::Bar() if it exists.
-
-This commit finally enforces this convention. Note that this broke a
-number of existing tests for properties, since they didn't always use an
-Is/In prefix.
+"In" or "Is". However, Perl did not actually enforce that naming
+restriction, so \p{foo::bar} could call foo::bar() if it existed. Now this
+convention has been enforced.
-=head2 User-defined regular expression properties
-
-Perl no longer allows a tainted regular expression to invoke a user-defined
-property via C<\p{...}> syntax. It simply dies instead [perl #82616].
+Also, Perl no longer allows a tainted regular expression to invoke a
+user-defined. It simply dies instead [perl #82616].
=head1 Incompatible Changes
-=head2 "C<\cI<X>>"
-
-The backslash-c construct was designed as a way of specifying
-non-printable characters, but there were no restrictions (on ASCII
-platforms) on what the character following the C<c> could be. Now, that
-character must be one of the ASCII characters.
-
-=head2 localised tied hashes, arrays and scalars are no longed tied
-
-In the following:
-
- tie @a, ...;
- {
- local @a;
- # here, @a is a now a new, untied array
- }
- # here, @a refers again to the old, tied array
-
-The new local array used to be made tied too, which was fairly pointless,
-and has now been fixed. This fix could however potentially cause a change
-in behaviour of some code.
-
-=head2 C<given> return values
-
-Starting from this release, C<given> blocks returns the last evaluated
-expression, or an empty list if the block was exited by C<break>. Thus you
-can now write:
-
- my $type = do {
- given ($num) {
- break when undef;
- 'integer' when /^[+-]?[0-9]+$/;
- 'float' when /^[+-]?[0-9]+(?:\.[0-9]+)?$/;
- 'unknown';
- }
- };
-
-See L<perlsyn/Return value> for details.
-
-=head2 localised tied scalars are tied again.
-
-The change in behaviour in 5.13.1 of localising tied scalar values has
-been reverted to the existing 5.12.0 and earlier behaviour (the change for
-arrays and hashes remains).
-
-=head2 Naming fixes in Policy_sh.SH may invalidate Policy.sh
-
-Several long-standing typos and naming confusions in Policy_sh.SH have
-been fixed, standardizing on the variable names used in config.sh.
-
-This will change the behavior of Policy.sh if you happen to have been
-accidentally relying on the Policy.sh incorrect behavior. We'd appreciate
-feedback from anyone using Policy.sh to be sure nothing is broken by
-this change (c1bd23).
-
-=head2 Stashes are now always defined
-
-C<defined %Foo::> now always returns true, even when no symbols have yet been
-defined in that package.
+Perl 5.14.0 is not binary-compatible with any previous stable release.
-This is a side effect of removing a special case kludge in the tokeniser,
-added for 5.10.0, to hide side effects of changes to the internal storage of
-hashes that to drastically reduce their memory usage overhead.
+In addition to the sections that follow, see L</C API Changes>.
-Calling defined on a stash has been deprecated since 5.6.0, warned on
-lexicals since 5.6.0, and has warned for stashes (and other package
-variables) since 5.12.0. C<defined %hash> has always exposed an
-implementation detail - emptying a hash by deleting all entries from it does
-not make C<defined %hash> false, hence C<defined %hash> is not valid code to
-determine whether an arbitrary hash is empty. Instead, use the behaviour
-that an empty C<%hash> always returns false in a scalar context.
+=head2 Regular Expressions and String Escapes
-=head2 \400 - \777
+=head3 \400-\777
-Use of C<\400> - C<\777> in regexes in certain circumstances has given
+Use of C<\400>-C<\777> in regexes in certain circumstances has given
different, anomalous behavior than their use in all other
double-quote-like contexts. Since 5.10.1, a deprecated warning message
has been raised when this happens. Now, all double-quote-like contexts
files whole; previously, this was documented only for C<"-0777">. It is
recommended, however, because of various ambiguities, to use the new
C<\o{...}> construct to represent characters in octal.
-(fa1639c..f6993e9).
-
-=head2 Declare API incompatibility between blead releases
-
-Only stable releases (5.10.x, 5.12.x, 5.14.x, ...) guarantee binary
-compatibility with each other, while blead releases (5.13.x, 5.15.x, ...) often
-break this compatibility. However, prior to perl 5.13.4, all blead releases had
-the same C<PERL_API_REVISION>, C<PERL_API_VERSION>, and C<PERL_API_SUBVERSION>,
-effectively declaring them as binary compatible, which they weren't. From now
-on, blead releases will have a C<PERL_API_SUBVERSION> equal to their
-C<PERL_SUBVERSION>, explicitly marking them as incompatible with each other.
-
-Maintenance releases of stable perl versions will continue to make no
-intentionally incompatible API changes.
-
-=head2 Check API compatibility when loading XS modules
-
-When perl's API changes in incompatible ways (which usually happens between
-every major release), XS modules compiled for previous versions of perl will not
-work anymore. They will need to be recompiled against the new perl.
-
-In order to ensure that modules are recompiled, and to prevent users from
-accidentally loading modules compiled for old perls into newer ones, the
-C<XS_APIVERSION_BOOTCHECK> macro has been added. That macro, which is called
-when loading every newly compiled extension, compares the API version of the
-running perl with the version a module has been compiled for and raises an
-exception if they don't match.
-
-=head2 Binary Incompatible with all previous Perls
-
-Some bit fields have been reordered; therefore, this release will not be binary
-compatible with any previous Perl release.
-
-=head2 Change in the parsing of certain prototypes
-
-Functions declared with the following prototypes now behave correctly as unary
-functions:
-
-=over 4
-
-=item *
-
-C<*>
-
-=item *
-
-C<\sigil>
-
-=item *
-
-C<\[...]>
-
-=item *
-
-C<;$>
-
-=item *
-
-C<;*>
-
-=item *
-
-C<;\sigil>
-
-=item *
-
-C<;\[...]>
-
-=back
-
-Due to this bug fix, functions using the C<(*)>, C<(;$)> and C<(;*)> prototypes
-are parsed with higher precedence than before. So in the following example:
- sub foo($);
- foo $a < $b;
-
-the second line is now parsed correctly as C<< foo($a) < $b >>, rather than
-C<< foo($a < $b) >>. This happens when one of these operators is used in
-an unparenthesised argument:
-
- < > <= >= lt gt le ge
- == != <=> eq ne cmp ~~
- &
- | ^
- &&
- || //
- .. ...
- ?:
- = += -= *= etc.
+=head3 Most C<\p{}> properties are now immune to case-insensitive matching
-=head2 Magic variables outside the main package
-
-In previous versions of Perl, magic variables like C<$!>, C<%SIG>, etc. would
-'leak' into other packages. So C<%foo::SIG> could be used to access signals,
-C<${"foo::!"}> (with strict mode off) to access C's C<errno>, etc.
-
-This was a bug, or an 'unintentional' feature, which caused various ill effects,
-such as signal handlers being wiped when modules were loaded, etc.
+For most Unicode properties, it doesn't make sense to have them match
+differently under C</i> case-insensitive matching than not. And doing
+so leads to unexpected results and potential security holes. For
+example
-This has been fixed (or the feature has been removed, depending on how you see
-it).
+ m/\p{ASCII_Hex_Digit}+/i
-=head2 Smart-matching against array slices
+could previously match non-ASCII characters because of the Unicode
+matching rules (although there were a number of bugs with this). Now
+matching under C</i> gives the same results as non-C</i> matching except
+for those few properties where people have come to expect differences,
+namely the ones where casing is an integral part of their meaning, such
+as C<m/\p{Uppercase}/i> and C<m/\p{Lowercase}/i>, both of which match
+the exact same code points, namely those matched by C<m/\p{Cased}/i>.
+Details are in L<perlrecharclass/Unicode Properties>.
-Previously, the following code resulted in a successful match:
+User-defined property handlers that need to match differently under
+C</i> must change to read the new boolean parameter passed to them which is
+non-zero if case-insensitive matching is in effect or 0 otherwise. See
+L<perluniprops/User-Defined Character Properties>.
- my @a = qw(a y0 z);
- my @b = qw(a x0 z);
- @a[0 .. $#b] ~~ @b;
+=head3 \p{} implies Unicode semantics
-This odd behaviour has now been fixed [perl #77468].
+Now, a Unicode property match specified in the pattern will indicate
+that the pattern is meant for matching according to Unicode rules, the way
+C<\N{}> does.
-=head2 C API changes
+=head3 Regular expressions retain their localeness when interpolated
-The first argument of the C API function C<Perl_fetch_cop_label> has changed
-from C<struct refcounted he *> to C<COP *>, to better insulate the user from
-implementation details.
+Regular expressions compiled under C<"use locale"> now retain this when
+interpolated into a new regular expression compiled outside a
+C<"use locale">, and vice-versa.
-This API function was marked as "may change", and likely isn't in use outside
-the core. (Neither an unpacked CPAN, nor Google's codesearch, finds any other
-references to it.)
+Previously, a regular expression interpolated into another one inherited
+the localeness of the surrounding one, losing whatever state it
+originally had. This is considered a bug fix, but may trip up code that
+has come to rely on the incorrect behavior.
-=head2 Stringification of regexes has changed
+=head3 Stringification of regexes has changed
Default regular expression modifiers are now notated by using
C<(?^...)>. Code relying on the old stringification will fail. The
automatically incorporate the new modifiers.
Code that needs to work properly with both old- and new-style regexes
-can avoid the whole issue by using (for Perls since 5.9.5):
+can avoid the whole issue by using (for Perls since 5.9.5; see L<re>):
use re qw(regexp_pattern);
my ($pat, $mods) = regexp_pattern($re_ref);
-where C<$re_ref> is a reference to a compiled regular expression. Upon
-return, C<$mods> will be a string containing all the non-default
-modifiers used when the regular expression was compiled, and C<$pattern>
-the actual pattern.
-
If the actual stringification is important, or older Perls need to be
supported, you can use something like the following:
And then use C<$modifiers> instead of C<-xism>.
-=head2 Regular expressions retain their localeness when interpolated
+=head3 Run-time code blocks in regular expressions inherit pragmata
-Regular expressions compiled under C<"use locale"> now retain this when
-interpolated into a new regular expression compiled outside a
-C<"use locale">, and vice-versa.
+Code blocks in regular expressions (C<(?{...})> and C<(??{...})>) used not
+to inherit any pragmata (strict, warnings, etc.) if the regular expression
+was compiled at run time as happens in cases like these two:
-Previously, a regular expression interpolated into another one inherited
-the localeness of the surrounding one, losing whatever state it
-originally had. This is considered a bug fix, but may trip up code that
-has come to rely on the incorrect behavior.
+ use re 'eval';
+ $foo =~ $bar; # when $bar contains (?{...})
+ $foo =~ /$bar(?{ $finished = 1 })/;
-=head2 Directory handles not copied to threads
+This was a bug, which has now been fixed. But it has the potential to break
+any code that was relying on it.
-On systems that do not have a C<fchdir> function, newly-created threads no
-longer inherit directory handles from their parent threads. Such programs
-would probably have crashed anyway [perl #75154].
+=head2 Stashes and Package Variables
-=head2 Negation treats strings differently from before
+=head3 Localised tied hashes and arrays are no longed tied
-The unary negation operator C<-> now treats strings that look like numbers
-as numbers [perl #57706].
+In the following:
-=head2 Negative zero
+ tie @a, ...;
+ {
+ local @a;
+ # here, @a is a now a new, untied array
+ }
+ # here, @a refers again to the old, tied array
-Negative zero (-0.0), when converted to a string, now becomes "0" on all
-platforms. It used to become "-0" on some, but "0" on others.
+The new local array used to be made tied too, which was fairly pointless,
+and has now been fixed. This fix could however potentially cause a change
+in behaviour of some code.
-If you still need to determine whether a zero is negative, use
-C<sprintf("%g", $zero) =~ /^-/> or the L<Data::Float> module on CPAN.
+=head3 Stashes are now always defined
+
+C<defined %Foo::> now always returns true, even when no symbols have yet been
+defined in that package.
+
+This is a side effect of removing a special case kludge in the tokeniser,
+added for 5.10.0, to hide side effects of changes to the internal storage of
+hashes that drastically reduce their memory usage overhead.
+
+Calling defined on a stash has been deprecated since 5.6.0, warned on
+lexicals since 5.6.0, and warned for stashes (and other package
+variables) since 5.12.0. C<defined %hash> has always exposed an
+implementation detail - emptying a hash by deleting all entries from it does
+not make C<defined %hash> false, hence C<defined %hash> is not valid code to
+determine whether an arbitrary hash is empty. Instead, use the behaviour
+that an empty C<%hash> always returns false in a scalar context.
-=head2 Dereferencing typeglobs
+=head3 Dereferencing typeglobs
If you assign a typeglob to a scalar variable:
This would result in strange behaviour in edge cases: C<untie $scalar>
would do nothing if the last thing assigned to the scalar was a glob
(because it treated it as C<untie *$scalar>, which unties a handle).
-Assignment to a glob slot (e.g., C<(*$glob) = \@some_array>) would simply
+Assignment to a glob slot (e.g., C<*$glob = \@some_array>) would simply
assign C<\@some_array> to C<$glob>.
To fix this, the C<*{}> operator (including the C<*foo> and C<*$foo> forms)
has been modified to make a new immutable glob if its operand is a glob
-copy. Various operators that make a distinction between globs and scalars
-have been modified to treat only immutable globs as globs.
+copy. This allows operators that make a distinction between globs and
+scalars to be modified to treat only immutable globs as globs. (C<tie>,
+C<tied> and C<untie> have been left as they are for compatibility's sake,
+but will warn. See L</Deprecations>.)
This causes an incompatible change in code that assigns a glob to the
return value of C<*{}> when that operator was passed a glob copy. Take the
glob is made an alias to C<*bar>. Then it is discarded. So the second
assignment has no effect.
-It also means that C<tie $handle> will now tie C<$handle> as a scalar, even
-if it has had a glob assigned to it.
-
-The upside to this incompatible change is that bugs [perl #77496],
-[perl #77502], [perl #77508], [perl #77688], and [perl #77812],
-and maybe others, too, have been fixed.
-
See L<http://rt.perl.org/rt3/Public/Bug/Display.html?id=77810> for even
more detail.
-=head2 Clearing stashes
+=head3 Clearing stashes
Stash list assignment C<%foo:: = ()> used to make the stash anonymous
temporarily while it was being emptied. Consequently, any of its
C<caller> will return the original sub name if there is still a reference
to its typeglob, or "foo::__ANON__" otherwise [perl #79208].
-=head2 C<:=> is now a syntax error
-
-Previously C<my $pi := 4;> was exactly equivalent to C<my $pi : = 4;>,
-with the C<:> being treated as the start of an attribute list, ending before
-the C<=>. The use of C<:=> to mean C<: => was deprecated in 5.12.0, and is now
-a syntax error. This will allow the future use of C<:=> as a new token.
-
-We find no Perl 5 code on CPAN using this construction, outside the core's
-tests for it, so we believe that this change will have very little impact on
-real-world codebases.
-
-If it is absolutely necessary to have empty attribute lists (for example,
-because of a code generator) then avoid the error by adding a space before
-the C<=>.
+=head3 Magic variables outside the main package
-=head2 Run-time code block in regular expressions
+In previous versions of Perl, magic variables like C<$!>, C<%SIG>, etc. would
+'leak' into other packages. So C<%foo::SIG> could be used to access signals,
+C<${"foo::!"}> (with strict mode off) to access C's C<errno>, etc.
-Code blocks in regular expressions (C<(?{...})> and C<(??{...})>) used not
-to inherit any pragmata (strict, warnings, etc.) if the regular expression
-was compiled at run time as happens in cases like these two:
+This was a bug, or an 'unintentional' feature, which caused various ill effects,
+such as signal handlers being wiped when modules were loaded, etc.
- use re 'eval';
- $foo =~ $bar; # when $bar contains (?{...})
- $foo =~ /$bar(?{ $finished = 1 })/;
+This has been fixed (or the feature has been removed, depending on how you see
+it).
-This was a bug, which has now been fixed. But it has the potential to break
-any code that was relying on this bug.
+=head2 Changes to Syntax or to Perl Operators
-=head2 All objects are destroyed
+=head3 C<given> return values
-It used to be possible to prevent a destructor from being called during
-global destruction by artificially increasing the reference count of an
-object.
+C<given> blocks now return the last evaluated
+expression, or an empty list if the block was exited by C<break>. Thus you
+can now write:
-Now such objects I<will> will be destroyed, as a result of a bug fix
-[perl #81230].
+ my $type = do {
+ given ($num) {
+ break when undef;
+ 'integer' when /^[+-]?[0-9]+$/;
+ 'float' when /^[+-]?[0-9]+(?:\.[0-9]+)?$/;
+ 'unknown';
+ }
+ };
-This has the potential to break some XS modules. (In fact, it break some.
-See L</Known Problems>, below.)
+See L<perlsyn/Return value> for details.
-=head2 Most C<\p{}> properties are now immune from case-insensitive matching
+=head3 Change in the parsing of certain prototypes
-For most Unicode properties, it doesn't make sense to have them match
-differently under C</i> case-insensitive matching than not. And doing
-so leads to unexpected results and potential security holes. For
-example
+Functions declared with the following prototypes now behave correctly as unary
+functions:
- m/\p{ASCII_Hex_Digit}+/i
+ *
+ \$ \% \@ \* \&
+ \[...]
+ ;$ ;*
+ ;\$ ;\% etc.
+ ;\[...]
-could previously match non-ASCII characters because of the Unicode
-matching rules. There were a number of bugs in this feature until an
-earlier release in the 5.13 series. Now this release reverts, and
-removes the feature completely except for the few properties where
-people have come to expect it, namely the ones where casing is an
-integral part of their functionality, such as C<m/\p{Uppercase}/i> and
-C<m/\p{Lowercase}/i>, both of which match the exact same code points,
-namely those matched by C<m/\p{Cased}/i>. Details are in
-L<perlrecharclass/Unicode Properties>.
+Due to this bug fix [perl #75904], functions
+using the C<(*)>, C<(;$)> and C<(;*)> prototypes
+are parsed with higher precedence than before. So in the following example:
-User-defined property handlers that need to match differently under
-C</i> must change to read the new boolean parameter passed it which is
-non-zero if case-insensitive matching is in effect; 0 if not. See
-L<perluniprops/User-Defined Character Properties>.
+ sub foo($);
+ foo $a < $b;
-=head2 regex: \p{} in pattern implies Unicode semantics
+the second line is now parsed correctly as C<< foo($a) < $b >>, rather than
+C<< foo($a < $b) >>. This happens when one of these operators is used in
+an unparenthesised argument:
-Now, a Unicode property match specified in the pattern will indicate
-that the pattern is meant for matching according to Unicode rules
-(e40e74f)
+ < > <= >= lt gt le ge
+ == != <=> eq ne cmp ~~
+ &
+ | ^
+ &&
+ || //
+ .. ...
+ ?:
+ = += -= *= etc.
-=head2 add GvCV_set() and GvGP_set() macros and change GvGP()
+=head3 Smart-matching against array slices
-This allows a future commit to eliminate some backref magic between GV
-and CVs, which will require complete control over assignment to the
-gp_cv slot.
+Previously, the following code resulted in a successful match:
+
+ my @a = qw(a y0 z);
+ my @b = qw(a x0 z);
+ @a[0 .. $#b] ~~ @b;
+
+This odd behaviour has now been fixed [perl #77468].
+
+=head3 Negation treats strings differently from before
+
+The unary negation operator C<-> now treats strings that look like numbers
+as numbers [perl #57706].
+
+=head3 Negative zero
+
+Negative zero (-0.0), when converted to a string, now becomes "0" on all
+platforms. It used to become "-0" on some, but "0" on others.
+
+If you still need to determine whether a zero is negative, use
+C<sprintf("%g", $zero) =~ /^-/> or the L<Data::Float> module on CPAN.
-If you've been using GvGP() in lvalue context this change will break
-your code, you should use GvGP_set() instead. (c43ae56)
+=head3 C<:=> is now a syntax error
-=head2 _swash_inversion_hash is no longer exported as part of the API
+Previously C<my $pi := 4;> was exactly equivalent to C<my $pi : = 4;>,
+with the C<:> being treated as the start of an attribute list, ending before
+the C<=>. The use of C<:=> to mean C<: => was deprecated in 5.12.0, and is now
+a syntax error. This will allow the future use of C<:=> as a new token.
-This function shouldn't be called from XS code. (4c2e113)
+We find no Perl 5 code on CPAN using this construction, outside the core's
+tests for it, so we believe that this change will have very little impact on
+real-world codebases.
-=head2 Unreferenced objects in global destruction
+If it is absolutely necessary to have empty attribute lists (for example,
+because of a code generator) then avoid the error by adding a space before
+the C<=>.
-The fix for [perl #36347], which made sure that destructors were called on
-unreferenced objects, broke the tests for three CPAN modules, which
-apparently rely on the bug.
+=head2 Threads and Processes
-To provide more time for fixing them (as this is such a minor bug), we
-have reverted the fix until after perl 5.14.0.
+=head3 Directory handles not copied to threads
-This resolves [perl #82542] and other related tickets.
+On systems other than Windows that do not have
+a C<fchdir> function, newly-created threads no
+longer inherit directory handles from their parent threads. Such programs
+would usually have crashed anyway [perl #75154].
-=head2 C<close> on shared pipes
+=head3 C<close> on shared pipes
The C<close> function no longer waits for the child process to exit if the
underlying file descriptor is still in use by another thread, to avoid
deadlocks. It returns true in such cases.
-=head2 Passing references to warn()
+=head3 fork() emulation will not wait for signalled children
-An earlier Perl 5.13.x release changed C<warn($ref)> to leave the reference
-unchanged, allowing C<$SIG{__WARN__}> handlers to access the original
-reference. But this stopped warnings that were references from having the
-file and line number appended even when there was no C<$SIG{__WARN__}>
-handler in place.
+On Windows parent processes would not terminate until all forked
+childred had terminated first. However, C<kill('KILL', ...)> is
+inherently unstable on pseudo-processes, and C<kill('TERM', ...)>
+might not get delivered if the child if blocked in a system call.
-Now C<warn> checks for the presence of such a handler and, if there is
-none, proceeds to stringify the reference and append the file and line
-number. This allows simple uses of C<warn> for debugging to continue to
-work as they did before.
+To avoid the deadlock and still provide a safe mechanism to terminate
+the hosting process, Perl will now no longer wait for children that
+have been sent a SIGTERM signal. It is up to the parent process to
+waitpid() for these children if child clean-up processing must be
+allowed to finish. However, it is also the responsibility of the
+parent then to avoid the deadlock by making sure the child process
+can't be blocked on I/O either.
-=head1 Deprecations
+See L<perlfork> for more information about the fork() emulation on
+Windows.
-The following items are now deprecated.
+=head2 Configuration
-=over 4
+=head3 Naming fixes in Policy_sh.SH may invalidate Policy.sh
-=item C<Perl_ptr_table_clear>
+Several long-standing typos and naming confusions in Policy_sh.SH have
+been fixed, standardizing on the variable names used in config.sh.
-C<Perl_ptr_table_clear> 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.
+This will change the behavior of Policy.sh if you happen to have been
+accidentally relying on the Policy.sh incorrect behavior.
-=item *
+=head3 Perl source code is read in text mode on Windows
-Omitting a space between a regex pattern or pattern modifiers and the following
-word is deprecated. For example, C<< m/foo/sand $bar >> will still be parsed
-as C<< m/foo/s and $bar >> but will issue a warning.
+Perl scripts used to be read in binary mode on Windows for the benefit
+of the ByteLoader module (which is no longer part of core Perl). This
+had the side effect of breaking various operations on the DATA filehandle,
+including seek()/tell(), and even simply reading from DATA after file handles
+have been flushed by a call to system(), backticks, fork() etc.
-=back
+The default build options for Windows have been changed to read Perl source
+code on Windows in text mode now. Hopefully ByteLoader will be updated on
+CPAN to automatically handle this situation [perl #28106].
+
+=head1 Deprecations
+
+See also L</Deprecated C APIs>.
=head2 Omitting a space between a regular expression and subsequent word
-Omitting a space between a regex pattern or pattern modifiers and the
-following word is deprecated. Deprecation for regular expression
-I<matches> was added in Perl 5.13.2. In this release, the deprecation
-is extended to regular expression I<substitutions>. For example,
-C<< s/foo/bar/sand $bar >> will still be parsed as
-C<< s/foo/bar/s and $bar >> but will issue a warning. (aa78b66)
+Omitting a space between a regular expression operator or
+its modifiers and the following word is deprecated. For
+example, C<< m/foo/sand $bar >> will still be parsed
+as C<< m/foo/s and $bar >> but will issue a warning.
+
+=head2 C<\cI<X>>
+
+The backslash-c construct was designed as a way of specifying
+non-printable characters, but there were no restrictions (on ASCII
+platforms) on what the character following the C<c> could be. Now,
+a deprecation warning is raised if that character isn't an ASCII character.
+Also, a deprecation warning is raised for C<"\c{"> (which is the same
+as simply saying C<";">).
+
+=head2 C<"\b{"> and C<"\B{">
+
+In regular expressions, a literal C<"{"> immediately following a C<"\b">
+(not in a bracketed character class) or a C<"\B{"> is now deprecated
+to allow for its future use by Perl itself.
=head2 Deprecation warning added for deprecated-in-core .pl libs
This is a mandatory warning, not obeying -X or lexical warning bits.
The warning is modelled on that supplied by deprecate.pm for
deprecated-in-core .pm libraries. It points to the specific CPAN
-distribution that contains the .pl libraries. The CPAN version, of
-course, does not generate the warning. (0111154)
+distribution that contains the .pl libraries. The CPAN version, of
+course, does not generate the warning.
=head2 List assignment to C<$[>
-After assignment to C<$[> has been deprecated and started to give warnings in
-perl version 5.12.0, this version of perl also starts to emit a warning when
-assigning to C<$[> in list context. This fixes an oversight in 5.12.0.
+Assignment to C<$[> was deprecated and started to give warnings in
+Perl version 5.12.0. This version of perl also starts to emit a warning when
+assigning to C<$[> in list context. This fixes an oversight in 5.12.0.
=head2 Use of qw(...) as parentheses
for $x qw(a b c) { ... }
The parser no longer lies to itself in this way. Wrap the list literal in
-parentheses, like:
+parentheses, like this:
for $x (qw(a b c)) { ... }
a warning. This is to allow future use of C<?> in new operators.
The match-once functionality is still available in the form of C<m?PATTERN?>.
-=head2 C<sv_compile_2op()> is now deprecated
-
-The C<sv_compile_2op()> API function is now deprecated. Searches suggest
-that nothing on CPAN is using it, so this should have zero impact.
-
-It attempted to provide an API to compile code down to an optree, but failed
-to bind correctly to lexicals in the enclosing scope. It's not possible to
-fix this problem within the constraints of its parameters and return value.
-
=head2 Tie functions on scalars holding typeglobs
Calling a tie function (C<tie>, C<tied>, C<untie>) with a scalar argument
a typeglob, and no way to untie a scalar that has had a typeglob
assigned to it.
-This bug was fixed in 5.13.7 but, because of the breakage it caused, the
-fix has been reverted. Now there is a deprecation warning whenever a tie
+Now there is a deprecation warning whenever a tie
function is used on a handle without an explicit C<*>.
-=over
+=head2 User-defined case-mapping
+
+This feature is being deprecated due to its many issues, as documented in
+L<perlunicode/User-Defined Case Mappings (for serious hackers only)>.
+It is planned to remove this feature in Perl 5.16. Instead use the CPAN module
+L<Unicode::Casing>, which provides improved functionality.
-=item Deprecated Modules
+=head2 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.
+core versions of these modules 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 repercussions of
-core module deprecations. You may want to consider shipping your default
+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
+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>
=back
-=back
-
-=head2 User-defined case-mapping
-
-This feature is being deprecated due to its many issues, as documented in
-L<perlunicode/User-Defined Case Mappings (for serious hackers only)>.
-It is planned to remove this feature in Perl 5.16. A CPAN module
-providing improved functionality is being prepared for release by the
-time 5.14 is.
-
=head1 Performance Enhancements
-=head2 "safe signals" optimization
+=head2 "Safe signals" optimisation
Signal dispatch has been moved from the runloop into control ops. This
should give a few percent speed increase, and eliminates almost all of
create uninterruptible loops, this is a bug, and reports are encouraged
of how to recreate such issues.
-=head2 Optimization of shift; and pop; calls without arguments
+=head2 Optimisation of shift; and pop; calls without arguments
-Additional two OPs are not added anymore into op tree for shift and pop
-calls without argument (when it works on C<@_>). Makes C<shift;> 5%
-faster over C<shift @_;> on not threaded perl and 25% faster on threaded.
+Two fewer OPs are used for shift and pop calls with no argument (with
+implicit C<@_>). This change makes C<shift;> 5% faster than C<shift @_;>
+on non-threaded perls and 25% faster on threaded.
-=head2 Adjacent pairs of nextstate opcodes are now optimized away
+=head2 Optimisation of regexp engine string comparison work
-Previously, in code such as
+The foldEQ_utf8 API function for case-insensitive comparison of strings (which
+is used heavily by the regexp engine) was substantially refactored and
+optimised - and its documentation much improved as a free bonus gift.
- use constant DEBUG => 0;
+=head2 Regular expression compilation speed-up
- sub GAK {
- warn if DEBUG;
- print "stuff\n";
- }
+Compiling regular expressions has been made faster for the case where upgrading
+the regex to utf8 is necessary but that isn't known when the compilation begins.
-the ops for C<warn if DEBUG;> would be folded to a C<null> op (C<ex-const>), but
-the C<nextstate> op would remain, resulting in a runtime op dispatch of
-C<nextstate>, C<nextstate>, ...
+=head2 String appending is 100 times faster
-The execution of a sequence of C<nextstate> ops is indistinguishable from just
-the last C<nextstate> op so the peephole optimizer now eliminates the first of
-a pair of C<nextstate> ops, except where the first carries a label, since labels
-must not be eliminated by the optimizer and label usage isn't conclusively known
-at compile time.
+When doing a lot of string appending, perl could end up allocating a lot more
+memory than needed in a very inefficient way, if perl was configured to use the
+system's C<malloc> implementation instead of its own.
+
+C<sv_grow>, which is what's being used to allocate more memory if necessary
+when appending to a string, has now been taught how to round up the memory
+it requests to a certain geometric progression, making it much faster on
+certain platforms and configurations. On Win32, it's now about 100 times
+faster.
+
+=head2 Eliminate C<PL_*> accessor functions under ithreads
+
+When C<MULTIPLICITY> was first developed, and interpreter state moved into
+an interpreter struct, thread and interpreter local C<PL_*> variables were
+defined as macros that called accessor functions, returning the address of
+the value, outside of the perl core. The intent was to allow members
+within the interpreter struct to change size without breaking binary
+compatibility, so that bug fixes could be merged to a maintenance branch
+that necessitated such a size change.
+
+However, some non-core code defines C<PERL_CORE>, sometimes intentionally
+to bypass this mechanism for speed reasons, sometimes for other reasons but
+with the inadvertent side effect of bypassing this mechanism. As some of
+this code is widespread in production use, the result is that the core
+I<can't> change the size of members of the interpreter struct, as it will
+break such modules compiled against a previous release on that maintenance
+branch. The upshot is that this mechanism is redundant, and well-behaved
+code is penalised by it. Hence it can and should be removed (and has
+been).
+
+=head2 Freeing weak references
-=head2 blah blah blah
+When an object has many weak references to it, freeing that object
+can under some some circumstances take O(N^2) time to free (where N is the
+number of references). The number of circumstances has been reduced
+[perl #75254]
-Only allocate entries for @_ on demand - this not only saves memory per
-subroutine defined but should hopefully improve COW behaviour (77bac2).
+=head2 Lexical array and hash assignments
-=head2 Multiple small improvements to threads
+An earlier optimisation to speed up C<my @array = ...> and
+C<my %hash = ...> assignments caused a bug and was disabled in Perl 5.12.0.
-The internal structures of threading now make fewer API calls and fewer
-allocations, resulting in noticeably smaller object code. Additionally,
-many thread context checks have been deferred so that they're only done
-when required (although this is only possible for non-debugging builds).
+Now we have found another way to speed up these assignments [perl #82110].
+
+=head2 C<@_> uses less memory
+
+Previously, C<@_> was allocated for every subroutine at compile time with
+enough space for four entries. Now this allocation is done on demand when
+the subroutine is called [perl #72416].
=head2 Size optimisations to SV and HV structures
xhv_fill has been eliminated from struct xpvhv, saving 1 IV per hash and
-on some systems will cause struct xpvhv to become cache aligned. To avoid
+on some systems will cause struct xpvhv to become cache-aligned. To avoid
this memory saving causing a slowdown elsewhere, boolean use of HvFILL
now calls HvTOTALKEYS instead (which is equivalent) - so while the fill
-data when actually required is now calculated on demand, the cases when
-this needs to be done should be few and far between (f4431c .. fcd245).
+data when actually required are now calculated on demand, the cases when
+this needs to be done should be few and far between.
-The order of structure elements in SV bodies has changed. Effectively,
-the NV slot has swapped location with STASH and MAGIC. As all access to
-SV members is via macros, this should be completely transparent. This
+The order of structure elements in SV bodies has changed. Effectively,
+the NV slot has swapped location with STASH and MAGIC. As all access to
+SV members is via macros, this should be completely transparent. This
change allows the space saving for PVHVs documented above, and may reduce
the memory allocation needed for PVIVs on some architectures.
-=head2 Optimisation of regexp engine string comparison work
+C<XPV>, C<XPVIV>, and C<XPVNV> now only allocate the parts of the C<SV> body
+they actually use, saving some space.
-The foldEQ_utf8 API function for case-insensitive comparison of strings (which
-is used heavily by the regexp engine) was substantially refactored and
-optimised - and its documentation much improved as a free bonus gift
-(8b3587, e6226b).
+Scalars containing regular expressions now only allocate the part of the C<SV>
+body they actually use, saving some space.
=head2 Memory consumption improvements to Exporter
The @EXPORT_FAIL AV is no longer created unless required, hence neither is
-the typeglob backing it - this saves about 200 bytes per Exporter using
-package that doesn't use this functionality.
-
-=head2 blah blah blah
-
-There are several small optimizations to reduce CPU cache misses in various very
-commonly used modules like C<warnings> and C<Carp> as well in accessing
-file-handles for reading. (5.13.3)
-
-XXX These need to be changed to =head2 entries, or the entries above need
-to change:
-
-=over 4
-
-=item *
-
-Make string appending 100 times faster
-
-When doing a lot of string appending, perl could end up allocating a lot more
-memory than needed in a very inefficient way, if perl was configured to use the
-system's C<malloc> implementation instead of its own.
+the typeglob backing it. This saves about 200 bytes for every package that
+uses Exporter but doesn't use this functionality.
-C<sv_grow>, which is what's being used to allocate more memory if necessary when
-appending to a string, has now been taught how to round up the memory it
-requests to a certain geometric progression, making it much faster on certain
-platforms and configurations. On Win32, it's now about 100 times faster.
-
-=item *
+=head2 Memory savings for weak references
For weak references, the common case of just a single weak reference per
referent has been optimised to reduce the storage required. In this case it
-saves the equivalent of one small perl array per referent.
-
-=item *
-
-C<XPV>, C<XPVIV>, and C<XPVNV> now only allocate the parts of the C<SV> body
-they actually use, saving some space.
-
-=item *
-
-Scalars containing regular expressions now only allocate the part of the C<SV>
-body they actually use, saving some space.
-
-=item *
-
-Compiling regular expressions has been made faster for the case where upgrading
-the regex to utf8 is necessary but that isn't known when the compilation begins.
+saves the equivalent of one small Perl array per referent.
-=item *
+=head2 C<%+> and C<%-> use less memory
The bulk of the C<Tie::Hash::NamedCapture> module used to be in the perl
-core. It has now been moved to an XS module, to reduce the overhead for
+core. It has now been moved to an XS module, to reduce the overhead for
programs that do not use C<%+> or C<%->.
-=item *
-
-Eliminate C<PL_*> accessor functions under ithreads.
-
-When C<MULTIPLICITY> was first developed, and interpreter state moved into an
-interpreter struct, thread and interpreter local C<PL_*> variables were defined
-as macros that called accessor functions, returning the address of the value,
-outside of the perl core. The intent was to allow members within the interpreter
-struct to change size without breaking binary compatibility, so that bug fixes
-could be merged to a maintenance branch that necessitated such a size change.
+=head2 Multiple small improvements to threads
-However, some non-core code defines C<PERL_CORE>, sometimes intentionally to
-bypass this mechanism for speed reasons, sometimes for other reasons but with
-the inadvertent side effect of bypassing this mechanism. As some of this code is
-widespread in production use, the result is that the core B<can't> change the
-size of members of the interpreter struct, as it will break such modules
-compiled against a previous release on that maintenance branch. The upshot is
-that this mechanism is redundant, and well-behaved code is penalised by
-it. Hence it can and should be removed.
+The internal structures of threading now make fewer API calls and fewer
+allocations, resulting in noticeably smaller object code. Additionally,
+many thread context checks have been deferred so that they're only done
+when required (although this is only possible for non-debugging builds).
-=item *
+=head2 Adjacent pairs of nextstate opcodes are now optimized away
-When an object has many weak references to it, freeing that object
-can under some some circumstances take O(N^2) time to free (where N is the
-number of references). The number of circumstances has been reduced
-[perl #75254]
+Previously, in code such as
-=item *
+ use constant DEBUG => 0;
-An earlier optimisation to speed up C<my @array = ...> and
-C<my %hash = ...> assignments caused a bug and was disabled in Perl 5.12.0.
+ sub GAK {
+ warn if DEBUG;
+ print "stuff\n";
+ }
-Now we have found another way to speed up these assignments [perl #82110].
+the ops for C<warn if DEBUG;> would be folded to a C<null> op (C<ex-const>), but
+the C<nextstate> op would remain, resulting in a runtime op dispatch of
+C<nextstate>, C<nextstate>, ....
-=back
+The execution of a sequence of C<nextstate> ops is indistinguishable from just
+the last C<nextstate> op so the peephole optimizer now eliminates the first of
+a pair of C<nextstate> ops, except where the first carries a label, since labels
+must not be eliminated by the optimizer and label usage isn't conclusively known
+at compile time.
=head1 Modules and Pragmata
=item *
-C<HTTP::Tiny> 0.010 has been added as a dual-life module. It is a very
+C<HTTP::Tiny> 0.011 has been added as a dual-life module. It is a very
small, simple HTTP/1.1 client designed for simple GET requests and file
mirroring. It has has been added to enable CPAN.pm and CPANPLUS to
"bootstrap" HTTP access to CPAN using pure Perl without relying on external
=item *
-C<Module::Metadata> 1.000003 has been added as a dual-life module. It gathers
+C<Module::Metadata> 1.000004 has been added as a dual-life module. It gathers
package and POD information from Perl module files. It is a standalone module
based on Module::Build::ModuleInfo for use by other module installation
toolchain components. Module::Build::ModuleInfo has been deprecated in
=back
-=head2 Updated Modules and Pragmata
+=head2 Updated Modules and Pragma
=over 4
=item *
-XXX Where does this go in the list?
+C<Archive::Extract> has been upgraded from version 0.38 to 0.48.
+
+Updates since 0.38 include: a safe print method that guards
+Archive::Extract from changes to $\; a fix to the tests when run in core
+perl; support for TZ files; a modification for the lzma
+logic to favour IO::Uncompress::Unlzma; and a fix
+for an issue with NetBSD-current and its new unzip
+executable.
+
+=item *
+
+C<Archive::Tar> has been upgraded from version 1.54 to 1.76.
-Perl 4 C<.pl> libraries
+Important changes since 1.54 include the following:
-These historical libraries have been minimally modified to avoid using
-C<$[>. This is to prepare them for the deprecation of C<$[>.
+=over
=item *
-C<Archive::Extract> has been upgraded from version 0.38 to 0.48.
+Compatibility with busybox implementations of tar
-Updates since 0.38 include: a safe print method that guards
-Archive::Extract from changes to $\; a fix to the tests when run in core
-perl; support for TZ files; and a modification for the lzma logic to favour
-IO::Uncompress::Unlzma
+=item *
-Resolves an issue with NetBSD-current and its new unzip
-executable.
+A fix so that C<write()> and C<create_archive()>
+close only handles they opened
=item *
-C<Archive::Tar> has been upgraded from version 1.54 to 1.76.
+A bug was fixed regarding the exit code of extract_archive.
-Important changes since 1.54 include: compatibility with busybox
-implementations of tar; a fix so that C<write()> and C<create_archive()>
-close only handles they opened; and a bug was fixed regarding the exit code
-of extract_archive. (afabe0e)
+=item *
-Among other things, the new version adds a new option to C<ptar> to allow safe
+The C<ptar> utility has a new option to allow safe
creation of tarballs without world-writable files on Windows, allowing those
archives to be uploaded to CPAN.
-This adds the ptargrep utility for using regular expressions against
-the contents of files in a tar archive.
+=item *
-Skip extracting pax extended headers.
+A new ptargrep utility for using regular expressions against
+the contents of files in a tar archive.
=item *
-C<autodie> has been upgraded from version 2.06_01 to 2.1001.
+Pax extended headers are now skipped.
+
+=back
=item *
=item *
-C<B::Debug> has been upgraded from version 1.12 to 1.16.
-
-=item *
-
C<B::Deparse> has been upgraded from version 0.96 to 1.02.
-A bug has been fixed when deparsing a nextstate op that has both a
+The deparsing of a nextstate op has changed when it has both a
change of package (relative to the previous nextstate), or a change of
C<%^H> or other state, and a label. Previously the label was emitted
-first, leading to syntactically invalid output because a label is not
-permitted immediately before a package declaration, B<BEGIN> block,
-or some other things. Now the label is emitted last.
+first, but now the label is emitted last (5.12.1).
-The 'no 5.13.2' or similar form is now correctly handled by B::Deparse.
+The C<no 5.13.2> or similar form is now correctly handled by B::Deparse
+(5.12.3).
B::Deparse now properly handles the code that applies a conditional
pattern match against implicit C<$_> as it was fixed in [perl #20444].
-It fixes deparsing of C<our> followed by a variable with funny characters
-(as permitted under the C<utf8> pragma) [perl #33752].
-
-=item *
-
-C<B::Lint> has been upgraded from version 1.11_01 to 1.12.
-
-=item *
-
-C<base> has been upgraded from version 2.15 to 2.16.
+Deparsing of C<our> followed by a variable with funny characters
+(as permitted under the C<utf8> pragma) has also been fixed [perl #33752].
=item *
-C<bignum> has been upgraded from version 0.23 to 0.25.
-
-=item *
-
-C<blib> has been upgraded from version 1.04 to 1.06.
-
-=item *
-
-C<Carp> has been upgraded from version 1.18 to 1.19.
+C<Carp> has been upgraded from version 1.15 to 1.19.
L<Carp> now detects incomplete L<caller()|perlfunc/"caller EXPR"> overrides and
-avoids using bogus C<@DB::args>. To provide backtraces, Carp relies on
-particular behaviour of the caller built-in. Carp now detects if other code has
+avoids using bogus C<@DB::args>. To provide backtraces,
+Carp relies on particular behaviour of the C<caller>
+built-in. Carp now detects if other code has
overridden this with an incomplete implementation, and modifies its backtrace
-accordingly. Previously incomplete overrides would cause incorrect values in
-backtraces (best case), or obscure fatal errors (worst case)
+accordingly. Previously incomplete overrides would cause incorrect values
+in backtraces (best case), or obscure fatal errors (worst case).
This fixes certain cases of C<Bizarre copy of ARRAY> caused by modules
-overriding C<caller()> incorrectly.
+overriding C<caller()> incorrectly (5.12.2).
-It now avoids using regular expressions that cause perl to
+It now also avoids using regular expressions that cause perl to
load its Unicode tables, in order to avoid the 'BEGIN not safe after
errors' error that will ensue if there has been a syntax error
[perl #82854].
C<CGI> has been upgraded from version 3.48 to 3.51.
This provides the following security fixes: the MIME boundary in
-multipart_init is now random and improvements to the handling of
-newlines embedded in header values.
-
-The documentation for param_fetch() has been corrected and clarified.
-
-=item *
-
-C<charnames> has been upgraded from version 1.07 to 1.10.
-
-C<viacode()> is now significantly faster.
+multipart_init is now random and the handling of
+newlines embedded in header values has been improved.
=item *
C<Compress::Raw::Bzip2> has been upgraded from version 2.024 to 2.033.
-Updated to use bzip2 1.0.6
+It has been updated to use bzip2 1.0.6.
=item *
-C<Compress::Raw::Zlib> has been upgraded from version 2.024 to 2.033.
+C<CPAN> has been upgraded from version 1.94_56 to 1.9600.
-=item *
+Major highlights:
-C<Compress::Zlib> has been upgraded from version 2.024 to 2.027.
+=over 4
-=item *
+=item * much less configuration dialog hassle
-C<CPAN> has been upgraded from version 1.94_56 to 1.94_63.
+=item * support for META/MYMETA.json
-=over 4
+=item * support for local::lib
-=item * release 1.94_57
+=item * support for HTTP::Tiny to reduce the dependency on ftp sites
-=item * bugfix: treat modules correctly that are deprecated in perl 5.12.
+=item * automatic mirror selection
-=item * bugfix: RT #57482 and #57788 revealed that configure_requires
-implicitly assumed build_requires instead of normal requires. (Reported
-by Andrew Whatson and Father Chrysostomos respectively)
+=item * iron out all known bugs in configure_requires
-=item * testfix: solaris should run the tests without expect because (some?)
-solaris have a broken expect
+=item * support for distributions compressed with bzip2
-=item * testfix: run tests with cache_metadata off to prevent spill over
-effects from previous test runs
+=item * allow Foo/Bar.pm on the commandline to mean Foo::Bar
=back
-Includes support for META.json and MYMETA.json.
-
=item *
-C<CPANPLUS> has been upgraded from version 0.90 to 0.9102.
+C<CPANPLUS> has been upgraded from version 0.90 to 0.9103.
-Fixed the shell test to skip if test is not being run under a terminal;
-resolved the issue where a prereq on Config would not be recognised as a
-core module.
+A change to F<cpanp-run-perl>
+resolves L<RT #55964|http://rt.cpan.org/Public/Bug/Display.html?id=55964>
+and L<RT #57106|http://rt.cpan.org/Public/Bug/Display.html?id=57106>, both
+of which related to failures to install distributions that use
+C<Module::Install::DSL> (5.12.2).
-Includes support for META.json and MYMETA.json and a change to
-using Digest::SHA for CPAN checksums.
+A dependency on Config was not recognised as a
+core module dependency. This has been fixed.
-=item *
-
-C<CPANPLUS::Dist::Build> has been upgraded from version 0.46 to 0.54.
-
-=item *
-
-C<Cwd> has been upgraded from version 3.31 to 3.36.
+CPANPLUS now includes support for META.json and MYMETA.json.
=item *
The indentation used to be off when C<$Data::Dumper::Terse> was set. This
has been fixed [perl #73604].
-This fixes a crash when using custom sort functions that might cause the stack
-to change.
+This upgrade also fixes a crash when using custom sort functions that might
+cause the stack to change [perl #74170].
C<Dumpxs> no longer crashes with globs returned by C<*$io_ref>
[perl #72332].
=item *
-C<DB_File> has been upgraded from version 1.820 to 1.821.
-
-=item *
-
-C<deprecate> has been upgraded from version 0.01 to 0.02.
-
-=item *
-
C<Devel::DProf> has been upgraded from version 20080331.00 to 20110228.00.
Merely loading C<Devel::DProf> now no longer triggers profiling to start.
the profiler.
NOTE: C<Devel::DProf> is deprecated and will be removed from a future
-version of Perl. We strongly recommend that you install and use
+version of Perl. We strongly recommend that you install and use
L<Devel::NYTProf> instead, as it offers significantly improved
profiling and reporting.
=item *
-C<Devel::Peek> has been upgraded from version 1.04 to 1.06.
-
-=item *
-
-C<Devel::SelfStubber> has been upgraded from version 1.03 to 1.05.
-
-=item *
-
C<diagnostics> has been upgraded from version 1.19 to 1.22.
It now renders pod links slightly better, and has been taught to find
C<Addfile> accepts all POSIX filenames.
-New SHA-512/224 and SHA-512/256 transforms ref. NIST Draft FIPS 180-4 (February 2011)
-
-=item *
-
-C<Dumpvalue> has been upgraded from version 1.13 to 1.15.
+New SHA-512/224 and SHA-512/256 transforms (ref. NIST Draft FIPS 180-4
+[February 2011])
=item *
C<Encode> has been upgraded from version 2.39 to 2.42.
Now, all 66 Unicode non-characters are treated the same way U+FFFF has
-always been treated; if it was disallowed, all 66 are disallowed; if it
-warned, all 66 warn.
-
-=item *
-
-C<Env> has been upgraded from version 1.01 to 1.02.
+always been treated; in cases when it was disallowed, all 66 are
+disallowed; in those cases where it warned, all 66 warn.
=item *
C<Errno> has been upgraded from version 1.11 to 1.13.
The implementation of C<Errno> has been refactored to use about 55% less memory.
-There should be no user-visible changes.
On some platforms with unusual header files, like Win32/gcc using mingw64
headers, some constants which weren't actually error numbers have been exposed
=item *
-C<ExtUtils::CBuilder> has been upgraded from 0.27 to 0.280201.
-
-Handle C and C++ compilers separately.
-
-Preserves exit status on VMS.
-
-=item *
-
-C<ExtUtils::Command> has been upgraded from version 1.16 to 1.17.
-
-=item *
-
C<ExtUtils::Constant> has been upgraded from 0.22 to 0.23.
The C<AUTOLOAD> helper code generated by C<ExtUtils::Constant::ProxySubs>
can now C<croak> for missing constants, or generate a complete C<AUTOLOAD>
-subroutine in XS, allowing simplification of many modules that use it.
-(C<Fcntl>, C<File::Glob>, C<GDBM_File>, C<I18N::Langinfo>, C<POSIX>, C<Socket>)
+subroutine in XS, allowing simplification of many modules that use it
+(C<Fcntl>, C<File::Glob>, C<GDBM_File>, C<I18N::Langinfo>, C<POSIX>,
+C<Socket>).
C<ExtUtils::Constant::ProxySubs> can now optionally push the names of all
-constants onto the package's C{@EXPORT_OK}. This has been used to replace
-less space-efficient code in C<B>, helping considerably shrink the size of its
-shared object.
-
-=item *
-
-C<ExtUtils::Constant::Utils> has been upgraded from 0.02 to 0.03.
-
-Refactoring and fixing of backcompat code, preparing for resynchronisation
-with CPAN.
-
-=item *
-
-C<ExtUtils::Embed> has been upgraded from 1.28 to 1.30.
-
-=item *
-
-C<ExtUtils::MakeMaker> has been upgraded from version 6.56 to 6.57_05.
-
-=item *
-
-C<ExtUtils::Manifest> has been upgraded from version 1.57 to 1.58.
-
-=item *
-
-C<ExtUtils::ParseXS> has been upgraded from 2.21 to 2.2208.
-
-=item *
-
-C<Fcntl> has been upgraded from 1.06 to 1.11.
-
-=item *
-
-C<File::Copy> has been downgraded from version 2.17 to 2.21.
-
-An extra stanza was added explaining behaviours when the copy destination
-already exists and is a directory.
+constants onto the package's C<@EXPORT_OK>.
=item *
C<File::DosGlob> has been upgraded from version 1.01 to 1.03.
It allows patterns containing literal parentheses (they no longer need to
-be escaped). On Windows, it no longer adds an extra F<./> to the file names
+be escaped). On Windows, it no longer
+adds an extra F<./> to the file names
returned when the pattern is a relative glob with a drive specification,
like F<c:*.pl> [perl #71712].
C<File::Find> has been upgraded from version 1.15 to 1.18.
-It improves handling of backslashes on Windows, so that paths such as
+It improves handling of backslashes on Windows, so that paths like
F<c:\dir\/file> are no longer generated [perl #71710].
=item *
-C<feature> has been upgraded from 1.16 to 1.19.
-
-Documentation and test updates for the C<unicode_strings> feature.
-See L</Full functionality for C<use feature 'unicode_strings'>>.
-
-=item *
-
-C<File::CheckTree> has been upgraded from 4.4 to 4.41.
-
-=item *
+C<File::Spec> has been upgraded from version 3.31 to 3.33.
-C<File::Glob> has been upgraded from 1.07 to 1.11.
+Several portability fixes were made in C<File::Spec::VMS>: a colon is now
+recognized as a delimiter in native filespecs; caret-escaped delimiters are
+recognized for better handling of extended filespecs; C<catpath()> returns
+an empty directory rather than the current directory if the input directory
+name is empty; C<abs2rel()> properly handles Unix-style input (5.12.2).
=item *
=item *
-C<Filter::Simple> has been upgraded from version 0.84 to 0.85.
-
-=item *
-
C<GDBM_File> has been upgraded from 1.10 to 1.13.
This fixes a memory leak when DBM filters are used.
C<Hash::Util> has been upgraded from 0.07 to 0.10.
-Hash::Util now enables "no warnings 'uninitialized'" to suppress spurious
-warnings from undefined hash values (RT #74280).
-
-=item *
-
-C<Hash::Util::FieldHash> has been upgraded from 1.04 to 1.07.
-
-=item *
-
-C<I18N::Collate> has been upgraded from 1.01 to 1.02.
+Hash::Util no longer emits spurious "uninitialized" warnings when
+recursively locking hashes that have undefined values [perl #74280].
=item *
C<I18N::Langinfo> has been upgraded from version 0.03 to 0.07.
C<langinfo()> now defaults to using C<$_> if there is no argument given, just
-like the documentation always claimed it did.
-
-=item *
-
-C<I18N::LangTags> has been upgraded from version 0.35 to 0.35_01.
-
-=item *
-
-C<if> has been upgraded from version 0.05 to 0.0601.
-
-=item *
-
-C<IO> has been upgraded from version 1.25_02 to 1.25_04.
-
-=item *
-
-The IO-Compress distribution has been upgraded from version 2.024 to 2.033.
+as the documentation has always claimed.
=item *
=item *
-C<IO::Socket> has been upgraded from version 1.31 to 1.32.
-
-C<getsockopt> and C<setsockopt> are now documented.
-
-=item *
-
-C<IPC::Cmd> has been upgraded from version 0.54 to 0.68.
+C<IPC::Cmd> has been upgraded from version 0.54 to 0.70.
-Resolves an issue with splitting Win32 command lines.
+Resolves an issue with splitting Win32 command lines. An argument
+consisting of the single character "0" used to be omitted (CPAN RT #62961).
=item *
=item *
-The Locale-Codes distribution has been upgraded from version 2.07 to 3.16.
-
-Locale::Country, Locale::Language and Locale::Currency were updated from
-3.12 to 3.13 of the Locale-Codes distribution to include locale code changes.
-
-Adds some codes.
-
-=item *
-
-C<Locale::Maketext> has been upgraded from version 1.14 to 1.17.
+C<Locale::Maketext> has been upgraded from version 1.14 to 1.19.
-Locale::Maketext guts have been merged back into the main module
-and adds external cache support
+Locale::Maketext now supports external caches.
-It fixes an infinite loop in C<Locale::Maketext::Guts::_compile()> when
+This upgrade also fixes an infinite loop in
+C<Locale::Maketext::Guts::_compile()> when
working with tainted values (CPAN RT #40727).
-C<< ->maketext >> calls will now backup and restore C<$@> so that error
+C<< ->maketext >> calls will now back up and restore C<$@> so that error
messages are not suppressed (CPAN RT #34182).
=item *
This fixes, among other things, incorrect results when computing binomial
coefficients [perl #77640].
-This prevents C<sqrt($int)> from crashing under C<use bigrat;>
+It also prevents C<sqrt($int)> from crashing under C<use bigrat;>
[perl #73534].
=item *
=item *
-C<Math::BigRat> has been upgraded from version 0.24 to 0.26_01.
+C<Math::BigRat> has been upgraded from version 0.24 to 0.26_02.
=item *
=item *
-C<Module::CoreList> has been upgraded from version 2.29 to XXX.
+C<Module::CoreList> has been upgraded from version 2.29 to 2.47.
Besides listing the updated core modules of this release, it also stops listing
-the C<Filespec> module. That module never existed in core. The scripts
+the C<Filespec> module. That module never existed in core. The scripts
generating C<Module::CoreList> confused it with C<VMS::Filespec>, which actually
-is a core module, since the time of perl 5.8.7.
+is a core module as of perl 5.8.7.
=item *
=item *
-C<Module::Load::Conditional> has been upgraded from version 0.34 to 0.40.
-
-=item *
-
-C<Module::Metadata> has been upgraded from version 1.000003 to 1.000004.
-
-XXX This is not listed in corelist for 5.12.0. When was it added?
-
-=item *
-
-C<mro> has been upgraded from version 1.02 to 1.06.
-
-C<next::method> I<et al.> now take into account that every class inherits
-from UNIVERSAL [perl #68654].
-
-=item *
-
-C<NDBM_File> has been upgraded from 1.08 to 1.11.
-
-This fixes a memory leak when DBM filters are used.
-
-=item *
-
-C<NEXT> has been upgraded from version 0.64 to 0.65.
+C<Module::Load::Conditional> has been upgraded from version 0.34 to 0.44.
=item *
-C<ODBM_File> has been upgraded from 1.08 to 1.09.
+C<NDBM_File> has been upgraded from version 1.08 to 1.11.
This fixes a memory leak when DBM filters are used.
=item *
-C<Net::Ping> has been upgraded from 2.36 to 2.37.
+C<Net::Ping> has been upgraded from version 2.36 to 2.38.
=item *
-C<ODBM_File> has been upgraded from 1.07 to 1.10.
+C<NEXT> has been upgraded from version 0.64 to 0.65.
=item *
=item *
-C<open> has been upgraded from version 1.07 to 1.08.
+C<ODBM_File> have been upgraded from version 1.07 to 1.10.
-=item *
-
-C<Opcode> has been upgraded from 1.15 to 1.18.
+This fixes a memory leak when DBM filters are used.
=item *
-C<overload> has been upgraded from 1.11 to 1.12.
+C<overload> has been upgraded from 1.10 to 1.12.
C<overload::Method> can now handle subroutines that are themselves blessed
into overloaded classes [perl #71998].
-Avoid a taint problem in use of sprintf.
-
The documentation has greatly improved. See L</Documentation> below.
=item *
C<Parse::CPAN::Meta> has been upgraded from version 1.40 to 1.4401.
-The latest Parse::CPAN::Meta can now read YAML or JSON files using
+The latest Parse::CPAN::Meta can now read YAML and JSON files using
L<CPAN::Meta::YAML> and L<JSON::PP>, which are now part of the Perl core.
=item *
-The PathTools distribution has been upgraded from version 3.31 to 3.34.
-
-Various issues in L<File::Spec::VMS> have been fixed. (5.13.4)
-
-=item *
-
-C<PerlIO::encoding> has been upgraded from 0.12 to 0.14.
-
-=item *
-
C<PerlIO::scalar> has been upgraded from 0.07 to 0.11.
A C<read> after a C<seek> beyond the end of the string no longer thinks it
=item *
-C<PerlIO::via> has been upgraded from 0.09 to 0.11.
-
-=item *
-
-The podlators distribution has been upgraded from version 2.3.1 to 2.4.0.
+C<Pod::LaTeX> has been upgraded from version 0.58 to 0.59.
=item *
-C<Pod::LaTeX> has been upgraded from version 0.58 to 0.59.
+C<Pod::Perldoc> has been upgraded from version 3.15_02 to 3.15_03.
=item *
-C<Pod::Simple> has been upgraded from 3.14 to 3.15
-
-Includes various fixes to C<HTML> and C<XHTML> handling.
+C<Pod::Simple> has been upgraded from version 3.13 to 3.16.
=item *
-C<POSIX> has been upgraded from 1.19 to 1.23.
+C<POSIX> has been upgraded from 1.19 to 1.24.
It now includes constants for POSIX signal constants.
=item *
-C<re> has been upgraded from version 0.11 to 0.15.
+C<re> has been upgraded from version 0.11 to 0.17.
New C<use re "/flags"> pragma
-Enforce that C</d>, C</u>, and C</l> are mutually exclusive.
-
-C<re> has been upgraded from version 0.16 to 0.17.
-
-It now supports the double-a flag: C<use re '/aa';>
-
The C<regmust> function used to crash when called on a regular expression
-belonging to a pluggable engine. Now it has been disabled for those.
+belonging to a pluggable engine. Now it croaks instead.
C<regmust> no longer leaks memory.
C<Safe> has been upgraded from version 2.25 to 2.29.
-This fixes a possible infinite loop when looking for coderefs.
-
-It adds C<&version::vxs::VCMP> to the default share.
+Coderefs returned by C<reval()> and C<rdo()> are now wrapped via
+C<wrap_code_refs> (5.12.1).
-=item *
+This fixes a possible infinite loop when looking for coderefs.
-C<SDBM_File> has been upgraded from 1.06 to 1.08.
+It adds several version::vxs::* routines to the default share.
=item *
=item *
-C<Socket> has been upgraded from version 1.87 to XXX.
+C<Socket> has been upgraded from version 1.87 to 1.94.
-It has several new functions for handling IPv6 addresses. (from 5.13.8)
-
-It provides new affordances for IPv6,
-including implementations of the C<Socket::getaddrinfo()> and
-C<Socket::getnameinfo()> functions, along with related constants.
+See L</IPv6 support>, above.
=item *
Includes performance improvement for overloaded classes.
-=item *
-
-C<Storable> has been upgraded from 2.24 to 2.25.
-
This adds support for serialising code references that contain UTF-8 strings
-correctly. The Storable minor version number changed as a result, meaning that
+correctly. The Storable minor version
+number changed as a result, meaning that
Storable users who set C<$Storable::accept_future_minor> to a C<FALSE> value
will see errors (see L<Storable/FORWARD COMPATIBILITY> for more details).
=item *
-C<Sys::Hostname> has been upgraded from 1.11 to 1.14.
-
-=item *
-
C<Term::ANSIColor> has been upgraded from version 2.02 to 3.00.
=item *
C<Test::Harness> has been upgraded from version 3.17 to 3.23.
-The core update from Test-Harness 3.17 to 3.21 fixed some things, but
-also L<introduced a known problem|/"Known Problems"> with argument
-passing to non-Perl tests. (5.13.3)
-
=item *
C<Test::Simple> has been upgraded from version 0.94 to 0.98.
=item *
-C<Thread::Queue> has been upgraded from version 2.11 to 2.12.
-
-=item *
-
C<Thread::Semaphore> has been upgraded from version 2.09 to 2.12.
-Added new methods -E<gt>down_nb() and -E<gt>down_force() at the suggestion
-of Rick Garlick.
+It provides two new methods that give more control over the decrementing of
+semaphores: C<down_nb> and C<down_force>.
+
+=item *
-Refactored methods to skip argument validation when no argument is supplied.
+C<Thread::Queue> has been upgraded from version 2.11 to 2.12.
=item *
-C<threads> has been upgraded from version 1.75 to 1.82.
+C<threads> has been upgraded from version 1.75 to 1.83.
=item *
=item *
-C<Tie::Hash::NamedCapture> has been upgraded from version 0.06 to 0.08.
-
-Some of the Perl code has been converted to XS for efficency's sake.
-
-=item *
-
C<Tie::RefHash> has been upgraded from version 1.38 to 1.39.
=item *
-C<Time::HiRes> has been upgraded from version 1.9719 to 1.9721.
+C<Time::HiRes> has been upgraded from version 1.9719 to 1.9721_01.
=item *
C<Unicode::Collate> has been upgraded from version 0.52_01 to 0.73.
-Includes Unicode Collation Algorithm 18
+Unicode::Collate has been updated to use Unicode 6.0.0.
-Among other things, it is now using UCA Revision 20 (based on Unicode 5.2.0) and
-supports a couple of new locales.
-
-U::C::Locale newly supports locales: ar, be, bg, de__phonebook, hu, hy, kk, mk, nso, om,
-tn, vi, hr, ig, ru, sq, se, sr, to and uk
-
-This release newly adds locales C<ja> C<ko> and C<zh> and its variants
-( C<zh__big5han>, C<zh__gb2312han>, C<zh__pinyin>, C<zh__stroke> ).
-
-Supported UCA_Version 22 for Unicode 6.0.0.
+Unicode::Collate::Locale now supports a plethora of new locales: ar, be,
+bg, de__phonebook, hu, hy, kk, mk, nso, om, tn, vi, hr, ig, ja, ko, ru, sq,
+se, sr, to, uk, zh, zh__big5han, zh__gb2312han, zh__pinyin and zh__stroke.
The following modules have been added:
C<Unicode::Collate::CJK::Stroke> for C<zh__stroke> which makes
tailoring of CJK Unified Ideographs in the order of CLDR's stroke ordering.
-DUCET has been updated for Unicode 6.0.0 as Collate/allkeys.txt and
-the default UCA_Version is 22.
-
This also sees the switch from using the pure-perl version of this
module to the XS version.
C<Unicode::UCD> has been upgraded from version 0.27 to 0.32.
-Add info about named sequence alternatives.
+A new function, C<Unicode::UCD::num()>, has been added. This function
+returns the numeric value of the string passed it or C<undef> if the string
+in its entirety has no "safe" numeric value. (For more detail, and for the
+definition of "safe", see L<Unicode::UCD/num>.)
-Don't use C<CompositionExclusions.txt>.
-
-This includes a number of bug fixes:
+This upgrade also includes a number of bug fixes:
=over 4
=item *
-The CJK (Chinese-Japanese-Korean) code points U+2A700 - U+2B734
-and U+2B740 - 2B81D are now properly handled.
+The CJK (Chinese-Japanese-Korean) code points U+2A700 to U+2B734
+and U+2B740 to U+2B81D are now properly handled.
=item *
=back
-Added new function C<Unicode::UCD::num()>. This function will return the
-numeric value of the string passed it; C<undef> if the string in its
-entirety has no safe numeric value.
-
-To be safe, a string must be a single character which has a numeric
-value, or consist entirely of characters that match \d, coming from the
-same Unicode block of digits. Thus, a mix of Bengali and Western
-digits would be considered unsafe, as well as a mix of half- and
-full-width digits, but strings consisting entirely of Devanagari digits
-or of "Mathematical Bold" digits would would be safe.
-
=item *
C<version> has been upgraded from 0.82 to 0.88.
-Modify export logic for C<is_strict> and C<is_lax>.
+Due to a bug, now fixed, the C<is_strict> and C<is_lax> functions did not
+work when exported (5.12.1).
=item *
-C<warnings> and C<warnings::register> have been upgraded from version 1.09
-to 1.11 and from version 1.01 to 1.02 respectively.
+C<warnings> has been upgraded from version 1.09 to 1.12.
Calling C<use warnings> without arguments is now significantly more efficient.
+=item *
+
+C<warnings::register> have been upgraded from version 1.01 to 1.02.
+
It is now possible to register warning categories other than the names of
packages using C<warnings::register>. See L<perllexwarn> for more information.
=item *
+C<XSLoader> has been upgraded from version 0.10 to 0.13.
+
+=item *
+
C<VMS::DCLsym> has been upgraded from version 1.03 to 1.05.
Two bugs have been fixed [perl #84086]:
C<Win32> has been upgraded from version 0.39 to 0.44.
-Add several functions. (5.13.8)
-
-Corrections to names returned by C<Win32::GetOSName> and
-C<Win32::GetOSDisplayName>.
-
-=item *
+This release has several new functions: C<Win32::GetSystemMetrics>,
+C<Win32::GetProductInfo>, C<Win32::GetOSDisplayName>.
-C<XSLoader> has been upgraded from version 0.10 to 0.11.
+The names returned by C<Win32::GetOSName> and C<Win32::GetOSDisplayName>
+have been corrected.
=back
-=head2 Dual-life Modules and Pragmata
-
-These modules were formerly distributed only in the Perl core
-distribution, and are now dual-lifed (meaning they are now also available
-separately on CPAN):
-
-=over 4
-
-=item *
-
-C<autouse>
-
-=item *
-
-C<Devel::SelfStubber>
+=head2 Removed Modules and Pragmata
-=item *
+The following modules have been removed from the core distribution, and if
+needed should be installed from CPAN instead.
-C<Dumpvalue>
+=over
=item *
-C<Env>
+C<Class::ISA> has been removed from the Perl core. Prior version was 0.36.
=item *
-C<File::CheckTree>
+C<Pod::Plainer> has been removed from the Perl core. Prior version was 1.02.
=item *
-C<I18N::Collate>
-
-=back
-
-=head2 Removed Modules and Pragmata
-
-The following modules have been removed from the core distribution, and if
-needed should be installed from CPAN instead.
-
-=over
-
-=item C<Class::ISA>
-
-=item C<Pod::Plainer>
-
-=item C<Switch>
+C<Switch> has been removed from the Perl core. Prior version was 2.16.
=back
=head1 Documentation
-XXX Changes to files in F<pod/> go here. Consider grouping entries by
-file and be sure to link to the appropriate page, e.g. L<perlfunc>.
-
=head2 New Documentation
-=head3 perlgpl
+=head3 L<perlgpl>
L<perlgpl> has been updated to contain GPL version 1, as is included in the
-F<README> distributed with perl.
+F<README> distributed with perl (5.12.1).
-=head3 L<perl5121delta>
+=head3 Perl 5.12.x delta files
-The Perl 5.12.1 perldelta file was added from the Perl maintenance branch
+The perldelta files for Perl 5.12.1 to 5.12.3 have been added from the
+maintenance branch: L<perl5121delta>, L<perl5122delta>, L<perl5123delta>.
=head3 L<perlpodstyle>
New style guide for POD documentation,
split mostly from the NOTES section of the pod2man man page.
-( This was added to C<v5.13.6> but was not documented with that release ).
+=head3 L<perlsource>, L<perlinterp>, L<perlhacktut>, and L<perlhacktips>
+
+See L</L<perlhack> and perlrepository revamp>, below.
=head2 Changes to Existing Documentation
-=head3 L<perlmodlib>
+=head3 L<perlmodlib> is now complete
The perlmodlib page that came with Perl 5.12.0 was missing a lot of
modules, due to a bug in the script that generates the list. This has been
-fixed [perl #74332].
+fixed [perl #74332] (5.12.1).
-=head3 Replace wrong tr/// table in perlebcdic.pod
+=head3 Replace wrong tr/// table in L<perlebcdic>
-perlebcdic.pod contains a helpful table to use in tr/// to convert
+L<perlebcdic> contains a helpful table to use in tr/// to convert
between EBCDIC and Latin1/ASCII. Unfortunately, the table was the
inverse of the one it describes, though the code that used the table
worked correctly for the specific example given.
The table has also been changed to hex from octal, as that is more the norm
these days, and the recipes in the pod altered to print out leading
-zeros to make all the values the same length, as the table that they can
-generate has them (5f26d5).
+zeros to make all the values the same length.
-=head3 Document tricks for user-defined casing
+=head3 Tricks for user-defined casing
-perlunicode.pod now contains an explanation of how to override, mangle
-and otherwise tweak the way perl handles upper, lower and other case
-conversions on unicode data, and how to provide scoped changes to alter
-one's own code's behaviour without stomping on anybody else (71648f).
-
-=head3 Document $# and $* as removed and clarify $#array usage
-
-$# and $* were both disabled as of perl5 version 10; this release adds
-documentation to that effect, a description of the results of continuing
-to try and use them, and a note explaining that $# can also function as a
-sigil in the $#array form (7f315d2).
+L<perlunicode> now contains an explanation of how to override, mangle
+and otherwise tweak the way perl handles upper-, lower- and other-case
+conversions on Unicode data, and how to provide scoped changes to alter
+one's own code's behaviour without stomping on anybody else.
=head3 INSTALL explicitly states the requirement for C89
-This was already true but it's now Officially Stated For The Record (51eec7).
+This was already true but it's now Officially Stated For The Record
+(5.12.2).
-=head3 No longer advertise Math::TrulyRandom
+=head3 Explanation of C<\xI<HH>> and C<\oI<OOO>> escapes
-This module hasn't been updated since 1996 so we can't recommend it any more
-(83918a).
+L<perlop> has been updated with more detailed explanation of these two
+character escapes.
-=head3 perlfaq synchronised to upstream
+=head3 C<-0I<NNN>> switch
-The FAQ has been updated to commit
-37550b8f812e591bcd0dd869d61677dac5bda92c from the perlfaq repository
-at git@github.com:briandfoy/perlfaq.git
+In L<perlrun>, the behavior of the C<-0NNN> switch for C<-0400> or higher
+has been clarified (5.12.2).
-=head3 General changes
+=head3 Maintenance policy
-=over
+L<perlpolicy> now contains the policy on what patches are acceptable for
+maintenance branches (5.12.1).
-=item *
+=head3 Deprecation policy
-Octal character escapes in documentation now prefer a three-digit octal
-escape or the new C<\o{...}> escape as they have more consistent behavior
-in different contexts than other forms. (ce7b6f0) (d8b950d) (e1f120a)
+L<perlpolicy> now contains the policy on compatibility and deprecation
+along with definitions of terms like "deprecation" (5.12.2).
-=item *
+=head3 New descriptions in L<perldiag>
-Documentation now standardizes on the term 'capture group' over 'buffer'
-in regular expression documentation (c27a5cf)
+The following existing diagnostics are now documented:
-=back
+=over 4
-=head3 L<perlfunc>
+=item *
-=over
+L<Ambiguous use of %c resolved as operator %c|perldiag/"Ambiguous use of %c resolved as operator %c">
=item *
-Added cautionary note about "no VERSION" (e0de7c2)
+L<Ambiguous use of %c{%s} resolved to %c%s|perldiag/"Ambiguous use of %c{%s} resolved to %c%s">
=item *
-Added additional notes regarding srand when forking (d460397)
+L<Ambiguous use of %c{%s%s} resolved to %c%s%s|perldiag/"Ambiguous use of %c{%s%s} resolved to %c%s%s">
-=back
+=item *
+
+L<Ambiguous use of -%s resolved as -&%s()|perldiag/"Ambiguous use of -%s resolved as -&%s()">
-=head3 L<perlop>
+=item *
-=over 4
+L<Invalid strict version format (%s)|perldiag/"Invalid strict version format (%s)">
=item *
-Improved documentation of unusual character escapes (4068718, 9644846)
+L<Invalid version format (%s)|perldiag/"Invalid version format (%s)">
=item *
-Clarified how hexadecimal escapes are interpreted, with particular
-attention to the treatment of invalid characters (9644846)
+L<Invalid version object|perldiag/"Invalid version object">
=back
-=head3 L<perlrun>
+=head3 L<perlbook>
-=over
+L<perlbook> has been expanded to cover many more popular books.
-=item *
+=head3 C<SvTRUE> macro
-Clarified the behavior of the C<-0NNN> switch for C<-0400> or higher (7ba31cb)
+The documentation for the C<SvTRUE> macro in
+L<perlapi> was simply wrong in stating that
+get-magic is not processed. It has been corrected.
-=back
+=head3 L<perlvar> revamp
-=head3 L<perlpolicy>
+L<perlvar> reorders the variables and groups them by topic. Each variable
+introduced after Perl 5.000 notes the first version in which it is
+available. L<perlvar> also has a new section for deprecated variables to
+note when they were removed.
-=over
+=head3 Array and hash slices in scalar context
-=item *
+These are now documented in L<perldata>.
-Added the policy on compatibility and deprecation along with definitions of
-terms like "deprecation" (70e4a83)
+=head3 C<use locale> and formats
-=back
+L<perlform> and L<perllocale> have been corrected to state that
+C<use locale> affects formats.
-=head3 L<perlre>
+=head3 L<overload>
-=over
+L<overload>'s documentation has practically undergone a rewrite. It
+is now much more straightforward and clear.
-=item *
+=head3 L<perlhack> and perlrepository revamp
-Added examples of the perils of not using \g{} when there are more
-than nine back-references (9d86067)
+The L<perlhack> and perlrepository documents have been heavily edited and
+split up into several new documents.
-=back
+The L<perlhack> document is now much shorter, and focuses on the Perl 5
+development process and submitting patches to Perl. The technical content has
+been moved to several new documents, L<perlsource>, L<perlinterp>,
+L<perlhacktut>, and L<perlhacktips>. This technical content has only been
+lightly edited.
-=head3 L<perltie>
+The perlrepository document has been renamed to L<perlgit>. This new document
+is just a how-to on using git with the Perl source code. Any other content
+that used to be in perlrepository has been moved to perlhack.
-=over
+=head3 Time::Piece examples
-=item *
+Examples in L<perlfaq4> have been updated to show the use of
+L<Time::Piece>.
-Updated some examples for modern Perl style (67d00dd)
+=head1 Diagnostics
-=back
+The following additions or changes have been made to diagnostic output,
+including warnings and fatal error messages. For the complete list of
+diagnostic messages, see L<perldiag>.
-=head3 L<perldiag>
+=head2 New Diagnostics
-=over 4
+=head3 New Errors
-=item *
+=over
-The following existing diagnostics are now documented:
+=item Closure prototype called
-=over 4
+This error occurs when a subroutine reference passed to an attribute
+handler is called, if the subroutine is a closure [perl #68560].
-=item *
+=item Insecure user-defined property %s
-L<Ambiguous use of %c resolved as operator %c|perldiag/"Ambiguous use of %c resolved as operator %c">
+Perl detected tainted data when trying to compile a regular
+expression that contains a call to a user-defined character property
+function, i.e. C<\p{IsFoo}> or C<\p{InFoo}>.
+See L<perlunicode/User-Defined Character Properties> and L<perlsec>.
-=item *
+=item panic: gp_free failed to free glob pointer - something is repeatedly re-creating entries
-L<Ambiguous use of %c{%s} resolved to %c%s|perldiag/"Ambiguous use of %c{%s} resolved to %c%s">
+This new error is triggered if a destructor called on an object in a
+typeglob that is being freed creates a new typeglob entry containing an
+object with a destructor that creates a new entry containing an object....
-=item *
+=item Parsing code internal error (%s)
-L<Ambiguous use of %c{%s%s} resolved to %c%s%s|perldiag/"Ambiguous use of %c{%s%s} resolved to %c%s%s">
+This new fatal error is produced when parsing
+code supplied by an extension violates the
+parser's API in a detectable way.
-=item *
+=item refcnt: fd %d%s
-L<Ambiguous use of -%s resolved as -&%s()|perldiag/"Ambiguous use of -%s resolved as -&%s()">
+This new error only occurs if a internal consistency check fails when a
+pipe is about to be closed.
-=item *
+=item Regexp modifier "/%c" may not appear twice
-L<Invalid strict version format (%s)|perldiag/"Invalid strict version format (%s)">
+The regular expression pattern has one of the
+mutually exclusive modifiers repeated.
-=item *
+=item Regexp modifiers "/%c" and "/%c" are mutually exclusive
-L<Invalid version format (%s)|perldiag/"Invalid version format (%s)">
+The regular expression pattern has more than one of the mutually
+exclusive modifiers.
-=item *
+=item Using !~ with %s doesn't make sense
-L<Invalid version object|perldiag/"Invalid version object">
+This error occurs when C<!~> is used with C<s///r> or C<y///r>.
=back
+=head3 New Warnings
+
+=over
+
+=item "\b{" is deprecated; use "\b\{" instead
+
+=item "\B{" is deprecated; use "\B\{" instead
+
+Use of an unescaped "{" immediately following a C<\b> or C<\B> is now
+deprecated so as to reserve its use for Perl itself in a future release.
+
+=item Operation "%s" returns its argument for ...
+
+Performing an operation requiring Unicode semantics (such as case-folding)
+on a Unicode surrogate or a non-Unicode character now triggers a warning:
+'Operation "%s" returns its argument for ...'.
+
+=item Use of qw(...) as parentheses is deprecated
+
+See L</"Use of qw(...) as parentheses">, above, for details.
+
=back
-=head3 L<perlport>
+=head2 Changes to Existing Diagnostics
=over 4
=item *
-Documented a L<limitation|perlport/alarm> of L<alarm()|perlfunc/"alarm SECONDS">
-on Win32.
+The "Variable $foo is not imported" warning that precedes a
+C<strict 'vars'> error has now been assigned the "misc" category, so that
+C<no warnings> will suppress it [perl #73712].
+
+=item *
+
+C<warn> and C<die> now produce 'Wide character' warnings when fed a
+character outside the byte range if STDERR is a byte-sized handle.
-=back
+=item *
-=head3 L<perlre>
+The 'Layer does not match this perl' error message has been replaced with
+these more helpful messages [perl #73754]:
=over 4
=item *
-Minor fix to a multiple scalar match example.
+PerlIO layer function table size (%d) does not match size expected by this
+perl (%d)
+
+=item *
+
+PerlIO layer instance size (%d) does not match size expected by this perl
+(%d)
=back
-=head3 L<perlapi>
+=item *
-=over 4
+The "Found = in conditional" warning that is emitted when a constant is
+assigned to a variable in a condition is now withheld if the constant is
+actually a subroutine or one generated by C<use constant>, since the value
+of the constant may not be known at the time the program is written
+[perl #77762].
=item *
-Many of the optree construction functions are now documented.
+Previously, if none of the C<gethostbyaddr>, C<gethostbyname> and
+C<gethostent> functions were implemented on a given platform, they would
+all die with the message 'Unsupported socket function "gethostent" called',
+with analogous messages for C<getnet*> and C<getserv*>. This has been
+corrected.
+
+=item *
+
+The warning message about unrecognized regular expression escapes passed
+through has been changed to include any literal '{' following the
+two-character escape. E.g., "\q{" is now emitted instead of "\q".
=back
-=head3 L<perlbook>
+=head1 Utility Changes
+
+=head3 L<perlbug>
=over 4
=item *
-Expanded to cover many more popular books.
+L<perlbug> now looks in the EMAIL environment variable for a return address
+if the REPLY-TO and REPLYTO variables are empty.
-=back
+=item *
-=head3 L<perlfaq>
+L<perlbug> did not previously generate a From: header, potentially
+resulting in dropped mail. Now it does include that header.
-=over 4
+=item *
+
+The user's address is now used as the return-path.
+
+Many systems these days don't have a valid Internet domain name and
+perlbug@perl.org does not accept email with a return-path that does
+not resolve. So the user's address is now passed to sendmail so it's
+less likely to get stuck in a mail queue somewhere [perl #82996].
+
+=item *
+
+L<perlbug> now always gives the reporter a chance to change the email
+address it guesses for them (5.12.2).
=item *
-L<perlfaq>, L<perlfaq2>, L<perlfaq4>, L<perlfaq5>, L<perlfaq6>, L<perlfaq8>, and
-L<perlfaq9> have seen various updates and modernizations.
+L<perlbug> should no longer warn about uninitialized values when using the C<-d>
+and C<-v> options (5.12.2).
=back
-=head3 L<perlapi>
+=head3 L<perl5db.pl>
-=over 4
+=over
=item *
-The documentation for the C<SvTRUE> macro was simply wrong in stating that
-get-magic is not processed. It has been corrected.
+The remote terminal works after forking and spawns new sessions - one
+for each forked process.
=back
-=head3 L<perlvar>
+=head3 L<ptargrep>
-L<perlvar> reorders the variables and groups them by topic. Each variable
-introduced after Perl 5.000 notes the first version in which it is
-available. L<perlvar> also has a new section for deprecated variables to
-note when they were removed.
+=over 4
-=head3 blah blah blah
+=item *
-Array and hash slices in scalar context are now documented in L<perldata>.
+L<ptargrep> is a new utility to apply pattern matching to the contents of
+files in a tar archive. It comes with C<Archive::Tar>.
-=head3 blah blah blah
+=back
-L<perlform> and L<perllocale> have been corrected to state that
-C<use locale> affects formats.
+=head1 Configuration and Compilation
-=head3 All documentation
+See also L</"Naming fixes in Policy_sh.SH may invalidate Policy.sh">,
+above.
-=over
+=over 4
=item *
-Numerous POD warnings were fixed.
+CCINCDIR and CCLIBDIR for the mingw64
+cross-compiler are now correctly under
+$(CCHOME)\mingw\include and \lib rather than immediately below $(CCHOME).
+
+This means the 'incpath', 'libpth', 'ldflags', 'lddlflags' and
+'ldflags_nolargefiles' values in Config.pm and Config_heavy.pl are now
+set correctly.
=item *
-Many, many spelling errors and typographical mistakes were corrected throughout Perl's core.
+'make test.valgrind' has been adjusted to account for cpan/dist/ext
+separation.
-=back
+=item *
+
+On compilers that support it, C<-Wwrite-strings> is now added to cflags by
+default.
-=head3 C<perlhack>
+=item *
-=over 4
+The C<Encode> module can now (once again) be included in a static Perl
+build. The special-case handling for this situation got broken in Perl
+5.11.0, and has now been repaired.
=item *
-C<perlhack> was extensively reorganized.
+The previous default size of a PerlIO buffer (4096 bytes) has been increased
+to the larger of 8192 bytes and your local BUFSIZ. Benchmarks show that doubling
+this decade-old default increases read and write performance in the neighborhood
+of 25% to 50% when using the default layers of perlio on top of unix. To choose
+a non-default size, such as to get back the old value or to obtain an even
+larger value, configure with:
-=back
+ ./Configure -Accflags=-DPERLIOBUF_DEFAULT_BUFSIZ=N
-=head3 C<perlfunc>
+where N is the desired size in bytes; it should probably be a multiple of
+your page size.
-=over 4
+=item *
+
+An "incompatible operand types" error in ternary expressions when building
+with C<clang> has been fixed (5.12.2).
=item *
-It has now been documented that C<ord> returns 0 for an empty string.
+Perl now skips setuid C<File::Copy> tests on partitions it detects to be mounted
+as C<nosuid> (5.12.2).
=back
-=head3 L<overload>
+=head1 Platform Support
+
+=head2 New Platforms
=over 4
-=item *
+=item AIX
-L<overload>'s documentation has practically undergone a rewrite. It
-is now much more straightforward and clear.
+Perl now builds on AIX 4.2 (5.12.1).
=back
-=head3 L<perlhack> and perlrepository
+=head2 Discontinued Platforms
=over 4
-=item *
+=item Apollo DomainOS
-The L<perlhack> and perlrepository documents have been heavily edited and
-split up into several new documents.
+The last vestiges of support for this platform have been excised from the
+Perl distribution. It was officially discontinued in version 5.12.0. It had
+not worked for years before that.
-The L<perlhack> document is now much shorter, and focuses on the Perl 5
-development process and submitting patches to Perl. The technical content has
-been moved to several new documents, L<perlsource>, L<perlinterp>,
-L<perlhacktut>, and L<perlhacktips>. This technical content has only been
-lightly edited.
+=item MacOS Classic
-The perlrepository document has been renamed to L<perlgit>. This new document
-is just a how-to on using git with the Perl source code. Any other content
-that used to be in perlrepository has been moved to perlhack.
+The last vestiges of support for this platform have been excised from the
+Perl distribution. It was officially discontinued in an earlier version.
=back
-=head3 L<perlfunc>
+=head2 Platform-Specific Notes
+
+=head3 AIX
-=over 4
+=over
=item *
-The documentation for the C<map> function now contains more examples,
-see B<perldoc -f map> (f947627)
+F<README.aix> has been updated with information about the XL C/C++ V11 compiler
+suite (5.12.2).
=back
-=head3 L<perlfaq4>
+=head3 ARM
-=over 4
+=over
=item *
-Examples in L<perlfaq4> have been updated to show the use of
-L<Time::Piece>. (9243591)
+The C<d_u32align> configuration probe on ARM has been fixed (5.12.2).
=back
-=head3 Miscellaneous
+=head3 Cygwin
=over 4
=item *
-Many POD related RT bugs and other issues which are too numerous to
-enumerate have been solved by Michael Stevens.
+MakeMaker has been updated to build man pages on cygwin.
-=back
+=item *
-=head1 Diagnostics
+Improved rebase behaviour
-The following additions or changes have been made to diagnostic output,
-including warnings and fatal error messages. For the complete list of
-diagnostic messages, see L<perldiag>.
+If a dll is updated on cygwin the old imagebase address is reused.
+This solves most rebase errors, especially when updating on core dll's.
+See L<http://www.tishler.net/jason/software/rebase/rebase-2.4.2.README> for more information.
-=head2 New Diagnostics
+=item *
-=over
+Support for the standard cygwin dll prefix, which is e.g. needed for FFI's
-=item Parsing code internal error (%s)
+=item *
-New fatal error produced when parsing code supplied by an extension violated the
-parser's API in a detectable way.
+Updated build hints file
-=item Use of qw(...) as parentheses is deprecated
+=back
-See L</"Use of qw(...) as parentheses"> for details.
+=head3 FreeBSD 7
-=item Using !~ with %s doesn't make sense
+=over
-This message was actually added in
-5.13.2, but was omitted from perldelta. It now applies also to the C<y///>
-operator, and has been documented.
+=item *
-=item Closure prototype called
+FreeBSD 7 no longer contains F</usr/bin/objformat>. At build time,
+Perl now skips the F<objformat> check for versions 7 and higher and
+assumes ELF (5.12.1).
-There is a new "Closure prototype called" error [perl #68560].
+=back
-=item Operation "%s" returns its argument for ...
+=head3 HP-UX
-Performing an operation requiring Unicode semantics (such as case-folding)
-on a Unicode surrogate or a non-Unicode character now triggers a warning:
-'Operation "%s" returns its argument for ...'.
+=over
-=item "\b{" is deprecated; use "\b\{" instead
+=item *
-=item "\B{" is deprecated; use "\B\{" instead
+Perl now allows -Duse64bitint without promoting to use64bitall on HP-UX
+(5.12.1).
-Use of an unescaped "{" immediately following a C<\b> or C<\B> is now
-deprecated so as to reserve its use for Perl itself in a future release.
+=back
-=item regcomp: Add warning if \p is used under locale. (fb2e24c)
+=head3 IRIX
-C<\p> implies Unicode matching rules, which are likely going to be
-different than the locale's.
+Conversion of strings to floating-point numbers is now more accurate on
+IRIX systems [perl #32380].
-=item panic: gp_free failed to free glob pointer - something is repeatedly re-creating entries
+=head3 Mac OS X
-This new error is triggered if a destructor called on an object in a
-typeglob that is being freed creates a new typeglob entry containing an
-object with a destructor that creates a new entry containing an object....
+Early versions of Mac OS X (Darwin) had buggy implementations of the
+C<setregid>, C<setreuid>, C<setrgid> and C<setruid> functions, so perl
+would pretend they did not exist.
-=item refcnt: fd %d%s
+These functions are now recognised on Mac OS 10.5 (Leopard; Darwin 9) and
+higher, as they have been fixed [perl #72990].
-This new error only occurs if a internal consistency check fails when a
-pipe is about to be closed.
+=head3 MirBSD
-=item Regexp modifier "/%c" may not appear twice
+Previously if you built perl with a shared libperl.so on MirBSD (the
+default config), it would work up to the installation; however, once
+installed, it would be unable to find libperl. So path handling is now
+treated as in the other BSD dialects.
-(F syntax) The regular expression pattern had one of the mutually exclusive
-modifiers repeated. Remove all but one of the occurrences.
+=head3 NetBSD
-=item Regexp modifiers "/%c" and "/%c" are mutually exclusive
+The NetBSD hints file has been changed to make the system's malloc the
+default.
-(F syntax) The regular expression pattern had more than one of the mutually
-exclusive modifiers. Retain only the modifier that is supposed to be there.
+=head3 Recent OpenBSDs now use perl's malloc
-=item Insecure user-defined property %s
+OpenBSD E<gt> 3.7 has a new malloc implementation which is mmap-based
+and as such can release memory back to the OS; however, perl's use of
+this malloc causes a substantial slowdown so we now default to using
+perl's malloc instead [perl #75742].
-(F) Perl detected tainted data when trying to compile a regular
-expression that contains a call to a user-defined character property
-function, i.e. C<\p{IsFoo}> or C<\p{InFoo}>.
-See L<perlunicode/User-Defined Character Properties> and L<perlsec>.
+=head3 OpenVOS
-=back
+perl now builds again with OpenVOS (formerly known as Stratus VOS)
+[perl #78132] (5.12.3).
-=head2 Changes to Existing Diagnostics
+=head3 Solaris
-=over 4
+DTrace is now supported on Solaris. There used to be build failures, but
+these have been fixed [perl #73630] (5.12.3).
-=item *
+=head3 VMS
-The "Variable $foo is not imported" warning that precedes a
-C<strict 'vars'> error has now been assigned the "misc" category, so that
-C<no warnings> will suppress it [perl #73712].
+=over
=item *
-C<warn> and C<die> now produce 'Wide character' warnings when fed a
-character outside the byte range if STDERR is a byte-sized handle.
+It's now possible to build extensions on older (pre 7.3-2) VMS systems.
+
+DCL symbol length was limited to 1K up until about seven years or
+so ago, but there was no particularly deep reason to prevent those
+older systems from configuring and building Perl (5.12.1).
=item *
-The 'Layer does not match this perl' error message has been replaced with
-these more helpful messages:
+We fixed the previously-broken C<-Uuseperlio> build on VMS.
-=over 4
+We were checking a variable that doesn't exist in the non-default
+case of disabling perlio. Now we only look at it when it exists (5.12.1).
=item *
-PerlIO layer function table size (%d) does not match size expected by this
-perl (%d)
+We fixed the -Uuseperlio command-line option in configure.com.
+
+Formerly it only worked if you went through all the questions
+interactively and explicitly answered no (5.12.1).
=item *
-PerlIO layer instance size (%d) does not match size expected by this perl
-(%d)
+C<PerlIOUnix_open> now honours the default permissions on VMS.
-=back
-
-[perl #73754]
-
-=item *
-
-The "Found = in conditional" warning that is emitted when a constant is
-assigned to a variable in a condition is now withheld if the constant is
-actually a subroutine or one generated by C<use constant>, since the value
-of the constant may not be known at the time the program is written
-[perl #77762].
-
-=item *
-
-Previously, if none of the C<gethostbyaddr>, C<gethostbyname> and
-C<gethostent> functions were implemented on a given platform, they would
-all die with the message 'Unsupported socket function "gethostent" called',
-with analogous messages for C<getnet*> and C<getserv*>. This has been
-corrected.
-
-=item *
-
-The warning message about regex unrecognized escapes passed through is
-changed to include any literal '{' following the 2-char escape. e.g.,
-"\q{" will include the { in the message as part of the escape
-(216bfc0).
-
-=item *
-
-C<binmode $fh, ':scalar'> no longer warns (8250589)
-
-Perl will now no longer produce this warning:
-
- $ perl -we 'open my $f, ">", \my $x; binmode $f, "scalar"'
- Use of uninitialized value in binmode at -e line 1.
-
-=back
-
-=head1 Utility Changes
-
-=head3 L<perldb>
-
-=over
-
-=item *
-
-The remote terminal works after forking and spawns new sessions - one
-for each forked process (11653f7)
-
-=item *
-
-Uses the less pager path from Config instead of searching for it (bf320d6)
-
-=back
-
-=head3 L<h2ph>
-
-=over 4
-
-=item *
-
-The use of a deprecated C<goto> construct has been removed [perl #74404].
-
-=back
-
-=head3 L<ptargrep>
-
-=over 4
-
-=item *
-
-L<ptargrep> is a utility to apply pattern matching to the contents of files
-in a tar archive. It comes with C<Archive::Tar>.
-
-=back
-
-=head3 C<perlbug>
-
-=over 4
-
-=item *
-
-C<perlbug> now looks in the EMAIL environment variable for a return address
-if the REPLY-TO and REPLYTO variables are empty.
-
-=item *
-
-C<perlbug> did not previously generate a From: header, potentially
-resulting in dropped mail. Now it does include that header.
-
-=back
-
-=head3 C<buildtoc>
+When C<perlio> became the default and C<unixio> became the default bottom layer,
+the most common path for creating files from Perl became C<PerlIOUnix_open>,
+which has always explicitly used C<0666> as the permission mask.
-=over 4
+To avoid this, C<0777> is now passed as the permissions to C<open()>. In the
+VMS CRTL, C<0777> has a special meaning over and above intersecting with the
+current umask; specifically, it allows Unix syscalls to preserve native default
+permissions (5.12.3).
=item *
-F<pod/buildtoc> has been modernized and can now be used to test the
-well-formedness of F<pod/perltoc.pod> automatically.
-
-=back
-
-=head3 L<perlbug>
-
-=over 4
+Spurious record boundaries are no longer
+introduced by the PerlIO layer during output (5.12.3).
=item *
-[perl #82996] Use the user's from address as return-path in perlbug
-
-Many systems these days don't have a valid Internet domain name and
-perlbug@perl.org does not accept email with a return-path that does
-not resolve. Therefore pass the user's address to sendmail so it's
-less likely to get stuck in a mail queue somewhere. (019cfd2)
-
-=back
-
-=head1 Configuration and Compilation
-
-=over 4
-
-=item *
-
-Fix CCINCDIR and CCLIBDIR for mingw64 cross compiler to correctly be under
-$(CCHOME)\mingw\include and \lib rather than immediately below $(CCHOME).
+The shortening of symbols longer than 31 characters in the C sources is
+now done by the compiler rather than by xsubpp (which could only do so
+for generated symbols in XS code).
=item *
-This means the 'incpath', 'libpth', 'ldflags', 'lddlflags' and
-'ldflags_nolargefiles' values in Config.pm and Config_heavy.pl are now
-set correctly (23ae7f).
+Record-oriented files (record format variable or variable with fixed control)
+opened for write by the perlio layer will now be line-buffered to prevent the
+introduction of spurious line breaks whenever the perlio buffer fills up.
=item *
-Adjusted 'make test.valgrind' to account for cpan/dist/ext separation
-(e07ce2e)
+F<git_version.h> is now installed on VMS. This was an oversight in v5.12.0 which
+caused some extensions to fail to build (5.12.2).
=item *
-Compatibility with C<C++> compilers has been improved.
+Several memory leaks in L<stat()|perlfunc/"stat FILEHANDLE"> have been fixed (5.12.2).
=item *
-On compilers that support it, C<-Wwrite-strings> is now added to cflags by
-default.
+A memory leak in C<Perl_rename()> due to a double allocation has been
+fixed (5.12.2).
=item *
-The C<Encode> module can now (once again) be included in a static Perl
-build. The special-case handling for this situation got broken in Perl
-5.11.0, and has now been repaired.
+A memory leak in C<vms_fid_to_name()> (used by C<realpath()> and
+C<realname()>) has been fixed (5.12.2).
=back
-=head1 Testing
+=head3 Windows
-XXX Any significant changes to the testing of a freshly built perl should be
-listed here. Changes which create B<new> files in F<t/> go here as do any
-large changes to the testing harness (e.g. when parallel testing was added).
-Changes to existing files in F<t/> aren't worth summarising, although the bugs
-that they represent may be covered elsewhere.
+See also L</"fork() emulation will not wait for signalled children"> and
+L</"Perl source code is read in text mode on Windows">, above.
=over 4
=item *
-F<t/harness> clears PERL5LIB, PERLLIB, PERL5OPT as t/TEST does (a2d3de1)
-
-=item *
-
-Many common testing routines were refactored into t/lib/common.pl
-
-=item *
-
-Several test files have been modernized to use Test::More
-
-=item *
-
-F<t/op/print.t> has been added to test implicit printing of C<$_>.
-
-=item *
-
-F<t/io/errnosig.t> has been added to test for restoration of of C<$!> when
-leaving signal handlers.
-
-=item *
-
-F<t/op/tie_fetch_count.t> has been added to see if C<FETCH> is only called once
-on tied variables.
-
-=item *
-
-F<lib/Tie/ExtraHash.t> has been added to make sure the, previously untested,
-L<Tie::ExtraHash> keeps working.
-
-=item *
-
-F<t/re/overload.t> has been added to test against string corruption in pattern
-matches on overloaded objects. This is a TODO test.
-
-=item *
-
-The new F<t/lib/universal.t> script tests the Internal::* functions and other
-things in F<universal.c>.
-
-=item *
-
-A rare race condition in F<t/op/while_readdir.t> has been fixed, stopping it
-from failing randomly when running tests in parallel.
-
-=item *
-
-The new F<t/op/leaky-magic.t> script tests that magic applied to variables in
-the main packages does not affect other packages.
-
-=item *
-
-The script F<t/op/threads-dirh.t> has been added, which tests interaction
-of threads and directory handles.
-
-=item *
-
-The new F<t/mro/isa_aliases.t> has been added, which tests that
-C<*Foo::ISA = *Bar::ISA> works properly.
-
-=item *
-
-F<t/mro/isarev.t> has been added, which tests that C<PL_isarev> (accessible
-at the Perl level via C<mro::get_isarev>) is updated properly.
-
-=item *
-
-F<t/run/switchd-78586.t> has been added, which tests that [perl #78586]
-has been fixed (related to line numbers in the debugger).
-
-=item *
-
-C<lib/File/DosGlob.t> has been modernized and now uses C<Test::More>.
-
-=item *
-
-A new test script, C<t/porting/filenames.t>, makes sure that filenames and
-paths are reasonably portable.
-
-=item *
-
-C<t/porting/diag.t> is now several orders of magnitude faster.
-
-=item *
-
-C<t/porting/buildtoc.t> now tests that the documentation TOC file is current and well-formed.
-
-=item *
-
-C<t/base/while.t> now tests the basics of a while loop with minimal dependencies.
-
-=item *
-
-C<t/cmd/while.t> now uses F<test.pl> for better maintainability.
-
-=item *
-
-C<t/op/split.t> now tests calls to C<split> without any pattern specified.
-
-=item *
-
-F<porting/FindExt.t> now skips all tests on a static (-Uusedl) build
-of perl.
-
-=item *
-
-F<porting/FindExt.t> now passes on non-Win32 platforms when some
-extensions are built statically.
-
-=item *
-
-The tests for C<split /\s/> and Unicode have been moved from
-F<t/op/split.t> to the new F<t/op/split_unicode.t>.
-
-=item *
-
-F<t/re/re.t> has been moved to F<ext/re/t/re_funcs_u.t>.
-
-=item *
-
-The tests for [perl #72922] have been moved from F<t/re/qr.t> to the new
-F<t/re/qr-72922.t>.
+Fixed build process for SDK2003SP1 compilers.
=item *
-F<t/re/reg_unsafe.t> has been deleted and its only test moved to
-F<t/re/pat_advanced.t>.
-
-=back
-
-=head1 Platform Support
-
-XXX Any changes to platform support should be listed in the sections below.
-
-[ Within the sections, list each platform as a =item entry with specific
-changes as paragraphs below it. ]
-
-=head2 New Platforms
-
-XXX List any platforms that this version of perl compiles on, that previous
-versions did not. These will either be enabled by new files in the F<hints/>
-directories, or new subdirectories and F<README> files at the top level of the
-source tree.
-
-=over 4
-
-=item AIX
-
-Perl now builds on AIX 4.2.
-
-=back
-
-=head2 Discontinued Platforms
-
-=over 4
-
-=item MacOS Classic
-
-Support for MacOS Classic within ExtUtils::MakeMaker was removed from Perl in
-December 2004. Vestigial MacOS Classic specific code has now been removed
-from other core modules as well (8f8c2a4..c457df0)
-
-=item Apollo DomainOS
-
-The last vestiges of support for this platform have been excised from the
-Perl distribution. It was officially discontinued in version 5.12.0. It had
-not worked for years before that.
-
-=item MacOS Classic
-
-The last vestiges of support for this platform have been excised from the
-Perl distribution. It was officially discontinued in an earlier version.
-
-=back
-
-=head2 Platform-Specific Notes
-
-=head3 Recent OpenBSDs now use perl's malloc
-
-OpenBSD E<gt> 3.7 has a new malloc implementation which is mmap based
-and as such can release memory back to the OS; however for perl using
-this malloc causes a substantial slowdown so we now default to using
-perl's malloc instead (RT #75742) (9b58b5).
-
-=head3 VMS
-
-=over 4
+Compilation with Visual Studio 2010 is now supported.
=item *
-Make C<PerlIOUnix_open> honour default permissions on VMS.
-
-When C<perlio> became the default and C<unixio> became the default bottom layer,
-the most common path for creating files from Perl became C<PerlIOUnix_open>,
-which has always explicitly used C<0666> as the permission mask.
-
-To avoid this, C<0777> is now passed as the permissions to C<open()>. In the
-VMS CRTL, C<0777> has a special meaning over and above intersecting with the
-current umask; specifically, it allows Unix syscalls to preserve native default
-permissions.
-
-=back
-
-=head3 Win32
-
-t/io/openpid.t now uses the alarm() watchdog strategy for more
-robustness (5732108)
-
-=over 4
+When using old 32-bit compilers, the define C<_USE_32BIT_TIME_T> will now
+be set in C<$Config{ccflags}>. This improves portability when compiling
+XS extensions using new compilers, but for a perl compiled with old 32-bit
+compilers.
=item *
-Fixed a possible hang in F<t/op/readline.t>.
+C<$Config{gccversion}> is now set correctly when perl is built using the
+mingw64 compiler from L<http://mingw64.org> [perl #73754].
=item *
-Fixed build process for SDK2003SP1 compilers.
+When building Perl with the mingw64 x64 cross-compiler C<incpath>,
+C<libpth>, C<ldflags>, C<lddlflags> and C<ldflags_nolargefiles> values
+in F<Config.pm> and F<Config_heavy.pl> were not previously being set
+correctly because, with that compiler, the include and lib directories
+are not immediately below C<$(CCHOME)> (5.12.2).
=item *
-When using old 32-bit compilers, the define C<_USE_32BIT_TIME_T> will now be set
-in C<$Config{ccflags}>. This improves portability when compiling XS extensions
-using new compilers, but for a perl compiled with old 32-bit compilers.
-
-=back
-
-XXX A bunch of entries that need conversion to =head2 format (unless the
-entries above change to =items):
-
-=over
-
-=item IRIX
-
-Conversion of strings to floating-point numbers is now more accurate on
-IRIX systems [perl #32380].
-
-=item Mac OS X
-
-Early versions of Mac OS X (Darwin) had buggy implementations of the
-C<setregid>, C<setreuid>, C<setrgid> and C<setruid> functions, so perl
-would pretend they did not exist.
-
-These functions are now recognised on Mac OS 10.5 (Leopard; Darwin 9) and
-higher, as they have been fixed [perl #72990].
-
-=item OpenVOS
-
-perl now builds again with OpenVOS (formerly known as Stratus VOS)
-[perl #78132].
-
-=item VMS
-
-The shortening of symbols longer than 31 characters in the C sources is
-now done by the compiler rather than by xsubpp (which could only do so
-for generated symbols in XS code).
-
-=item Windows
-
-C<$Config{gccversion}> is now set correctly when perl is built using the
-mingw64 compiler from L<http://mingw64.org> [perl #73754].
-
The build process proceeds more smoothly with mingw and dmake when
F<C:\MSYS\bin> is in the PATH, due to a C<Cwd> fix.
-=item Windows
-
-Directory handles are now properly cloned when threads are created. In perl
-5.13.6, child threads simply stopped inheriting directory handles. In
-previous versions, threads would share handles, resulting in crashes.
+=item *
Support for building with Visual C++ 2010 is now underway, but is not yet
-complete. See F<README.win32> for more details.
-
-=item VMS
-
-Record-oriented files (record format variable or variable with fixed control)
-opened for write by the perlio layer will now be line buffered to prevent the
-introduction of spurious line breaks whenever the perlio buffer fills up.
+complete. See F<README.win32> or L<perlwin32> for more details.
-=item NetBSD
-
-The NetBSD hints file has been changed to make the system's malloc the
-default.
-
-=item Windows
+=item *
The option to use an externally-supplied C<crypt()>, or to build with no
C<crypt()> at all, has been removed. Perl supplies its own C<crypt()>
implementation for Windows, and the political situation that required
this part of the distribution to sometimes be omitted is long gone.
-=item Cygwin
-
-=over
+=back
-=item *
+=head1 Internal Changes
-Updated MakeMaker to build man pages on cygwin.
+=head2 New APIs
-=item *
+=head3 CLONE_PARAMS structure added to ease correct thread creation
-Improved rebase behaviour
+Modules that create threads should now create C<CLONE_PARAMS> structures
+by calling the new function C<Perl_clone_params_new()>, and free them with
+C<Perl_clone_params_del()>. This will ensure compatibility with any future
+changes to the internals of the C<CLONE_PARAMS> structure layout, and that
+it is correctly allocated and initialised.
-If a dll is updated on cygwin reuse the old imagebase address.
-This solves most rebase errors, esp when updating on core dll's.
-See L<http://www.tishler.net/jason/software/rebase/rebase-2.4.2.README> for more information.
+=head3 New parsing functions
-=item *
+Several functions have been added for parsing statements or multiple
+statements:
-Support the standard cyg dll prefix, which is e.g. needed for FFI's.
+=over
=item *
-Updated build hints file
-
-=back
-
-
-=item Solaris
-
-DTrace is now supported on Solaris. There used to be build failures, but
-these have been fixed [perl #73630].
-
-=item Windows
-
-=over 4
+C<parse_fullstmt> parses a complete Perl statement.
=item *
-The C<test-prep> build target now depends on F<pod/perltoc.pod> to allow the
-F<t/porting/buildtoc.t> test to run successfully.
+C<parse_stmtseq> parses a sequence of statements, up
+to closing brace or EOF.
-=back
+=item *
-=item MirBSD
-
-=over 4
+C<parse_block> parses a block [perl #78222].
=item *
-[perl #82988] Skip hanging taint.t test on MirBSD 10 (1fb83d0)
-
-Skip a hanging test under MirBSD that was already being skipped under
-OpenBSD.
+C<parse_barestmt> parses a statement
+without a label.
=item *
-Previously if you build perl with a shared libperl.so on MirBSD (the
-default config), it will work up to the installation; however, once
-installed, it will be unable to find libperl. Treat path handling
-like in the other BSD dialects.
+C<parse_label> parses a statement label, separate from statements.
=back
-=back
-
-=head1 Internal Changes
-
-=head2 New APIs
-
-=head2 CLONE_PARAMS structure added to ease correct thread creation
-
-Modules that create threads should now create C<CLONE_PARAMS> structures
-by calling the new function C<Perl_clone_params_new()>, and free them with
-C<Perl_clone_params_del()>. This will ensure compatibility with any future
-changes to the internals of the C<CLONE_PARAMS> structure layout, and that
-it is correctly allocated and initialised.
-
-=head2 API function to parse statements
+The
+L<C<parse_fullexpr()>|perlapi/parse_fullexpr>,
+L<C<parse_listexpr()>|perlapi/parse_listexpr>,
+L<C<parse_termexpr()>|perlapi/parse_termexpr>, and
+L<C<parse_arithexpr()>|perlapi/parse_arithexpr>
+functions have been added to the API. They perform
+recursive-descent parsing of expressions at various precedence levels.
+They are expected to be used by syntax plugins.
-The C<parse_fullstmt> function has been added to allow parsing of a single
-complete Perl statement. See L<perlapi> for details.
+See L<perlapi> for details.
-=head2 API functions for accessing the runtime hinthash
+=head3 Hints hash API
-A new C API for introspecting the hinthash C<%^H> at runtime has been added.
-See C<cop_hints_2hv>, C<cop_hints_fetchpvn>, C<cop_hints_fetchpvs>,
+A new C API for introspecting the hinthash C<%^H> at runtime has been
+added. See C<cop_hints_2hv>, C<cop_hints_fetchpvn>, C<cop_hints_fetchpvs>,
C<cop_hints_fetchsv>, and C<hv_copy_hints_hv> in L<perlapi> for details.
-=head2 C interface to C<caller()>
+A new, experimental API has been added for accessing the internal
+structure that Perl uses for C<%^H>. See the functions beginning with
+C<cophh_> in L<perlapi>.
+
+=head3 C interface to C<caller()>
The C<caller_cx> function has been added as an XSUB-writer's equivalent of
C<caller()>. See L<perlapi> for details.
-=head2 Custom per-subroutine check hooks
+=head3 Custom per-subroutine check hooks
XS code in an extension module can now annotate a subroutine (whether
implemented in XS or in Perl) so that nominated XS code will be called
To help in writing custom check hooks, several subtasks within standard
C<entersub> op checking have been separated out and exposed in the API.
-=head2 Improved support for custom OPs
+=head3 Improved support for custom OPs
Custom ops can now be registered with the new C<custom_op_register> C
-function and the C<XOP> structure. This will make it easier to add new
-properties of custom ops in the future. Two new properties have been added
+function and the C<XOP> structure. This will make it easier to add new
+properties of custom ops in the future. Two new properties have been added
already, C<xop_class> and C<xop_peep>.
C<xop_class> is one of the OA_*OP constants, and allows L<B> and other
-introspection mechanisms to work with custom ops that aren't BASEOPs.
-C<xop_peep> is a pointer to a function that will be called for ops of this
+introspection mechanisms to work with custom ops
+that aren't BASEOPs. C<xop_peep> is a pointer to
+a function that will be called for ops of this
type from C<Perl_rpeep>.
See L<perlguts/Custom Operators> and L<perlapi/Custom Operators> for more
The old C<PL_custom_op_names>/C<PL_custom_op_descs> interface is still
supported but discouraged.
-=head2 Return value of C<delete $+{...}>
-
-Custom regular expression engines can now determine the return value of
-C<delete> on an entry of C<%+> or C<%->.
-
-XXX Mention the actual API.
-
-=head2 Changes to existing APIs
-
-XXX This probably contains also internal changes unrelated to APIs. It
-needs to be sorted out. Maybe we also need an ‘Other Changes’ or ‘Really
-Internal Changes’ section.
-
-=over 4
-
-=item *
-
-The protocol for unwinding the C stack at the last stage of a C<die>
-has changed how it identifies the target stack frame. This now uses
-a separate variable C<PL_restartjmpenv>, where previously it relied on
-the C<blk_eval.cur_top_env> pointer in the C<eval> context frame that
-has nominally just been discarded. This change means that code running
-during various stages of Perl-level unwinding no longer needs to take
-care to avoid destroying the ghost frame.
-
-=item *
-
-The format of entries on the scope stack has been changed, resulting in a
-reduction of memory usage of about 10%. In particular, the memory used by
-the scope stack to record each active lexical variable has been halved.
-
-=item *
-
-Memory allocation for pointer tables has been changed. Previously
-C<Perl_ptr_table_store> allocated memory from the same arena system as C<SV>
-bodies and C<HE>s, with freed memory remaining bound to those arenas until
-interpreter exit. Now it allocates memory from arenas private to the specific
-pointer table, and that memory is returned to the system when
-C<Perl_ptr_table_free> is called. Additionally, allocation and release are both
-less CPU intensive.
-
-=item *
-
-A new function, Perl_magic_methcall has been added that wraps the setup needed
-to call a magic method like FETCH (the existing S_magic_methcall function has
-been renamed S_magic_methcall1).
-
-=item *
-
-The implementation of sv_dup_inc() has changed from a macro to a function.
-
-=item *
-
-The C<find_rundefsvoffset> function has been deprecated. It appeared that
-its design was insufficient to reliably get the lexical C<$_> at run-time.
-
-Use the new C<find_rundefsv> function or the C<UNDERBAR> macro instead.
-They directly return the right SV representing C<$_>, whether it's lexical
-or dynamic (789bd8 .. 03d5bc).
-
-=item *
-
-The following new functions or macros have been added to the public API:
-C<SvNV_nomg>, C<sv_2nv_flags>, C<find_rundefsv>.
-
-=item *
-
-The C<UNDERBAR> macro now calls C<find_rundefsv>. C<dUNDERBAR> is now a
-noop but should still be used to ensure past and future compatibility.
-
-=item *
-
-The ibcmp_* functions have been renamed and are now called foldEQ,
-foldEQ_locale and foldEQ_utf8 (e6226b).
-
-=item *
-
-Under some circumstances, the C<CvGV()> field of a CV is now reference
-counted. To ensure consistent behaviour, direct assignment to it, for
-example C<CvGV(cv) = gv> is now a compile-time error. A new macro,
-C<CvGV_set(cv,gv)> has been introduced to perform this operation safely.
-Note that modification of this field is not part of of the public API,
-regardless of this new macro. This change caused some
-L<issues|/"Known Problems"> in modules that used the private C<GvGV()>
-field.
-
-=item *
+=head3 Scope hooks
It is now possible for XS code to hook into Perl's lexical scope
mechanism at compile time, using the new C<Perl_blockhook_register>
function. See L<perlguts/"Compile-time scope hooks">.
-=item *
-
-Added C<Perl_croak_no_modify()> to implement
-C<Perl_croak("%s", PL_no_modify)> (6ad8f25)
-
-=item *
-
-Added prototypes for C<tie()> and C<untie()> to allow overloading (RT#75902)
-(1db4d19)
-
-=item *
-
-Adds C<my_[l]stat_flags()> to replace C<my_[l]stat()>. C<my_stat()> and
-C<my_lstat()> call get magic on the stack arg, so create C<_flags()>
-variants that allow us to control this. (0d7d409)
-
-=item *
-
-Removed C<PERL_POLLUTE>
-
-The option to define C<PERL_POLLUTE> to expose older 5.005 symbols for backwards
-compatibility has been removed. It's use was always discouraged, and MakeMaker
-contains a more specific escape hatch:
-
- perl Makefile.PL POLLUTE=1
-
-This can be used for modules that have not been upgraded to 5.6 naming
-conventions (and really should be completely obsolete by now).
-
-=item *
-
-Added C<PERL_STATIC_INLINE>
-
-The C<PERL_STATIC_INLINE> define has been added to provide the best-guess
-incantation to use for static inline functions, if the C compiler supports
-C99-style static inline. If it doesn't, it'll give a plain C<static>.
-
-C<HAS_STATIC_INLINE> can be used to check if the compiler actually supports
-inline functions.
-
-=item *
-
-C<CALL_FPTR> and C<CPERLscope> have been deprecated.
-
-Those are left from an old implementation of C<MULTIPLICITY> using C++ objects,
-which was removed in Perl 5.8. Nowadays these macros do exactly nothing, so
-they shouldn't be used anymore.
-
-For compatibility, they are still defined for external C<XS> code. Only
-extensions defining C<PERL_CORE> must be updated now.
-
-=item *
-
-C<lex_stuff_pvs()> has been added as a convenience macro wrapping
-C<lex_stuff_pvn()> for literal strings.
-
-=item *
-
-The recursive part of the peephole optimizer is now hookable.
+=head3 The recursive part of the peephole optimizer is now hookable
In addition to C<PL_peepp>, for hooking into the toplevel peephole optimizer, a
C<PL_rpeepp> is now available to hook into the optimizer recursing into
side-chains of the optree.
-=item *
+=head3 New non-magical variants of existing functions
-See L</Regular expressions retain their localeness when interpolated>,
-above.
-
-=item *
+The following functions/macros have been added to the API. The C<*_nomg>
+macros are equivalent to their non-_nomg variants, except that they ignore
+get-magic. Those ending in C<_flags> allow one to specify whether
+get-magic is processed.
-The C<sv_cmp_flags>, C<sv_cmp_locale_flags>, C<sv_eq_flags> and
-C<sv_collxfrm_flags> functions have been added. These are like their
-non-_flags counterparts, but allow one to specify whether get-magic is
-processed.
+ sv_2bool_flags
+ SvTRUE_nomg
+ sv_2nv_flags
+ SvNV_nomg
+ sv_cmp_flags
+ sv_cmp_locale_flags
+ sv_eq_flags
+ sv_collxfrm_flags
-The C<sv_cmp>, C<sv_cmp_locale>, C<sv_eq> and C<sv_collxfrm> functions have
+In some of these cases, the non-_flags functions have
been replaced with wrappers around the new functions.
-=item *
+=head3 pv/pvs/sv versions of existing functions
-A new C<sv_2bool_flags> function has been added.
+Many functions ending with pvn now have equivalent pv/pvs/sv versions.
-This is like C<sv_2bool>, but it lets the calling code decide whether
-get-magic is handled. C<sv_2bool> is now a macro that calls the new
-function.
+=head3 List op-building functions
-=item *
+List op-building functions have been added to the
+API. See L<op_append_elem|perlapi/op_append_elem>,
+L<op_append_list|perlapi/op_append_list>, and
+L<op_prepend_elem|perlapi/op_prepend_elem> in L<perlapi>.
-A new macro, C<SvTRUE_nomg>, has been added.
+=head3 C<LINKLIST>
-This is like C<SvTRUE>, except that it does not process magic. It uses the
-new C<sv_2bool_flags> function.
+The L<LINKLIST|perlapi/LINKLIST> macro, part of op building that
+constructs the execution-order op chain, has been added to the API.
-=item *
+=head3 Localisation functions
-C<sv_catsv_flags> no longer calls C<mg_get> on its second argument (the
-source string) if the flags passed to it do not include SV_GMAGIC. So it
-now matches the documentation.
+The C<save_freeop>, C<save_op>, C<save_pushi32ptr> and C<save_pushptrptr>
+functions have been added to the API.
-=item *
+=head3 Stash names
-A new interface has been added for custom check hooks on subroutines. See
-L</Custom per-subroutine check hooks>, above.
+A stash can now have a list of effective names in addition to its usual
+name. The first effective name can be accessed via the C<HvENAME> macro,
+which is now the recommended name to use in MRO linearisations (C<HvNAME>
+being a fallback if there is no C<HvENAME>).
-=item *
+These names are added and deleted via C<hv_ename_add> and
+C<hv_ename_delete>. These two functions are I<not> part of the API.
+
+=head3 New functions for finding and removing magic
+
+The L<C<mg_findext()>|perlapi/mg_findext> and
+L<C<sv_unmagicext()>|perlapi/sv_unmagicext>
+functions have been added to the API.
+They allow extension authors to find and remove magic attached to
+scalars based on both the magic type and the magic virtual table, similar to how
+C<sv_magicext()> attaches magic of a certain type and with a given virtual table
+to a scalar. This eliminates the need for extensions to walk the list of
+C<MAGIC> pointers of an C<SV> to find the magic that belongs to them.
-List op building functions have been added to the
-API. See L<op_append_elem|perlapi/op_append_elem>,
-L<op_append_list|perlapi/op_append_list>, and
-L<op_prepend_elem|perlapi/op_prepend_elem>.
+=head3 C<find_rundefsv>
-=item *
+This function returns the SV representing C<$_>, whether it's lexical
+or dynamic.
-The L<LINKLIST|perlapi/LINKLIST> macro, part of op building that
-constructs the execution-order op chain, has been added to the API.
+=head3 C<Perl_croak_no_modify>
-=item *
+C<Perl_croak_no_modify()> is short-hand for
+C<Perl_croak("%s", PL_no_modify)>.
-Many functions ending with pvn now have equivalent pv/pvs/sv versions.
+=head3 C<PERL_STATIC_INLINE> define
-=item *
+The C<PERL_STATIC_INLINE> define has been added to provide the best-guess
+incantation to use for static inline functions, if the C compiler supports
+C99-style static inline. If it doesn't, it'll give a plain C<static>.
-The C<save_freeop>, C<save_op>, C<save_pushi32ptr> and C<save_pushptrptr>
-functions have been added to the API.
+C<HAS_STATIC_INLINE> can be used to check if the compiler actually supports
+inline functions.
-=item *
+=head3 New C<pv_escape> option for hexadecimal escapes
-The new API function C<parse_stmtseq()> parses a sequence of statements, up
-to closing brace or EOF.
+A new option, C<PERL_PV_ESCAPE_NONASCII>, has been added to C<pv_escape> to
+dump all characters above ASCII in hexadecimal. Before, one could get all
+characters as hexadecimal or the Latin1 non-ASCII as octal.
-=item *
+=head3 C<lex_start>
C<lex_start> has been added to the API, but is considered experimental.
-=item *
-
-A new C<parse_block> function has been added to the API [perl #78222].
-
-=item *
+=head3 C<op_scope()> and C<op_lvalue()>
-A new, experimental API has been added for accessing the internal
-structure that Perl uses for C<%^H>. See the functions beginning with
-C<cophh_> in L<perlapi>.
+The C<op_scope()> and C<op_lvalue()> functions have been added to the API,
+but are considered experimental.
-=item *
+=head2 C API Changes
-A stash can now have a list of effective names in addition to its usual
-name. The first effective name can be accessed via the C<HvENAME> macro,
-which is now the recommended name to use in MRO linearisations (C<HvNAME>
-being a fallback if there is no C<HvENAME>).
+=head3 C<PERL_POLLUTE> has been removed
-These names are added and deleted via C<hv_ename_add> and
-C<hv_ename_delete>. These two functions are I<not> part of the API.
+The option to define C<PERL_POLLUTE> to expose older 5.005 symbols for
+backwards compatibility has been removed. It's use was always discouraged,
+and MakeMaker contains a more specific escape hatch:
-=item *
+ perl Makefile.PL POLLUTE=1
-The way the parser handles labels has been cleaned up and refactored. As a
-result, the C<newFOROP()> constructor function no longer takes a parameter
-stating what label is to go in the state op.
+This can be used for modules that have not been upgraded to 5.6 naming
+conventions (and really should be completely obsolete by now).
-=item *
+=head3 Check API compatibility when loading XS modules
-The C<newWHILEOP()> and C<newFOROP()> functions no longer accept a line
-number as a parameter.
+When perl's API changes in incompatible ways (which usually happens between
+major releases), XS modules compiled for previous versions of perl will not
+work anymore. They will need to be recompiled against the new perl.
-=item *
+In order to ensure that modules are recompiled, and to prevent users from
+accidentally loading modules compiled for old perls into newer ones, the
+C<XS_APIVERSION_BOOTCHECK> macro has been added. That macro, which is
+called when loading every newly compiled extension, compares the API
+version of the running perl with the version a module has been compiled for
+and raises an exception if they don't match.
-A new C<parse_barestmt()> function has been added, for parsing a statement
-without a label.
+=head3 Perl_fetch_cop_label
-=item *
+The first argument of the C API function C<Perl_fetch_cop_label> has changed
+from C<struct refcounted he *> to C<COP *>, to insulate the user from
+implementation details.
-A new C<parse_label()> function has been added, that parses a statement
-label, separate from statements.
+This API function was marked as "may change", and likely isn't in use outside
+the core. (Neither an unpacked CPAN, nor Google's codesearch, finds any other
+references to it.)
-=item *
+=head3 GvCV() and GvGP() are no longer lvalues
-The C<CvSTASH()> macro can now only be used as an rvalue. C<CvSTASH_set()>
-has been added to replace assignment to C<CvSTASH()>. This is to ensure
-that backreferences are handled properly. These macros are not part of the
-API.
+The new GvCV_set() and GvGP_set() macros are now provided to replace
+assignment to those two macros.
-=item *
+This allows a future commit to eliminate some backref magic between GV
+and CVs, which will require complete control over assignment to the
+gp_cv slot.
-The C<op_scope()> and C<op_lvalue()> functions have been added to the API,
-but are considered experimental.
+=head3 CvGV() is no longer an lvalue
-=item *
+Under some circumstances, the C<CvGV()> field of a CV is now
+reference-counted. To ensure consistent behaviour, direct assignment to
+it, for example C<CvGV(cv) = gv> is now a compile-time error. A new macro,
+C<CvGV_set(cv,gv)> has been introduced to perform this operation
+safely. Note that modification of this field is not part of the public
+API, regardless of this new macro (and despite its being listed in this section).
-The L<C<mg_findext()>|perlapi/mg_findext> and
-L<C<sv_unmagicext()>|perlapi/sv_unmagicext>
-functions have been added to the API.
-They allow extension authors to find and remove magic attached to
-scalars based on both the magic type and the magic virtual table, similar to how
-C<sv_magicext()> attaches magic of a certain type and with a given virtual table
-to a scalar. This eliminates the need for extensions to walk the list of
-C<MAGIC> pointers of an C<SV> to find the magic that belongs to them.
+=head3 CvSTASH() is no longer an lvalue
-=item *
+The C<CvSTASH()> macro can now only be used as an rvalue. C<CvSTASH_set()>
+has been added to replace assignment to C<CvSTASH()>. This is to ensure
+that backreferences are handled properly. These macros are not part of the
+API.
-The
-L<C<parse_fullexpr()>|perlapi/parse_fullexpr>,
-L<C<parse_listexpr()>|perlapi/parse_listexpr>,
-L<C<parse_termexpr()>|perlapi/parse_termexpr>, and
-L<C<parse_arithexpr()>|perlapi/parse_arithexpr>
-functions have been added to the API. They perform
-recursive-descent parsing of expressions at various precedence levels.
-They are expected to be used by syntax plugins.
+=head3 Calling conventions for C<newFOROP> and C<newWHILEOP>
-=item *
+The way the parser handles labels has been cleaned up and refactored. As a
+result, the C<newFOROP()> constructor function no longer takes a parameter
+stating what label is to go in the state op.
-The opcode bodies for C<chop> and C<chomp> and for C<schop> and C<schomp> have
-been merged. The implementation functions C<Perl_do_chop()> and
-C<Perl_do_chomp()>, never part of the public API, have been merged and moved to
-a static function in F<pp.c>. This shrinks the perl binary slightly, and should
-not affect any code outside the core (unless it is relying on the order of side
-effects when C<chomp> is passed a I<list> of values).
+The C<newWHILEOP()> and C<newFOROP()> functions no longer accept a line
+number as a parameter.
-=item *
+=head3 Flags passed to C<uvuni_to_utf8_flags> and C<utf8n_to_uvuni>
-Some of the flags parameters to the uvuni_to_utf8_flags() and
-utf8n_to_uvuni() have changed. This is a result of Perl now allowing
+Some of the flags parameters to uvuni_to_utf8_flags() and
+utf8n_to_uvuni() have changed. This is a result of Perl's now allowing
internal storage and manipulation of code points that are problematic
in some situations. Hence, the default actions for these functions has
been complemented to allow these code points. The new flags are
documented in L<perlapi>. Code that requires the problematic code
-points to be rejected needs to change to use these flags. Some flag
+points to be rejected needs to change to use the new flags. Some flag
names are retained for backward source compatibility, though they do
nothing, as they are now the default. However the flags
C<UNICODE_ALLOW_FDD0>, C<UNICODE_ALLOW_FFFF>, C<UNICODE_ILLEGAL>, and
should be handled, which is now described in
L<perlunicode/Non-character code points>. See also L</Selected Bug Fixes>.
-=item *
-
-Certain shared flags in the C<pmop.op_pmflags> and C<regexp.extflags>
-structures have been removed. These are: C<Rxf_Pmf_LOCALE>,
-C<Rxf_Pmf_UNICODE>, and C<PMf_LOCALE>. Instead there are encodes and
-three static in-line functions for accessing the information:
-C<get_regex_charset()>, C<set_regex_charset()>, and C<get_regex_charset_name()>,
-which are defined in the places where the original flags were.
-
-=item *
-
-A new option has been added to C<pv_escape> to dump all characters above
-ASCII in hexadecimal. Before, one could get all characters as hexadecimal
-or the Latin1 non-ASCII as octal
-
-
-=item *
-
-Generate pp_* prototypes in pp_proto.h, and remove pp.sym
-
-Eliminate the #define pp_foo Perl_pp_foo(pTHX) macros, and update the 13
-locations that relied on them.
+XXX Which bugs in particular? Selected Bug Fixes is too long for this link
+to be meaningful right now
+I don't see the bugs in that section currently -- khw
-regen/opcode.pl now generates prototypes for the PP functions directly, into
-pp_proto.h. It no longer writes pp.sym, and regen/embed.pl no longer reads
-this, removing the only ordering dependency in the regen scripts. opcode.pl
-is now responsible for prototypes for pp_* functions. (embed.pl remains
-responsible for ck_* functions, reading from regen/opcodes)
+=head2 Deprecated C APIs
-=item *
+=over
-Fix harmless invalid read in Perl_re_compile() (f6d9469)
+=item C<Perl_ptr_table_clear>
-[perl #2460] described a case where electric fence reported an invalid
-read. This could be reproduced under valgrind with blead and -e'/x/',
-but only on a non-debugging build.
+C<Perl_ptr_table_clear> 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.
-This was because it was checking for certain pairs of nodes (e.g. BOL + END)
-and wasn't allowing for EXACT nodes, which have the string at the next
-node position when using a naive NEXTOPER(first). In the non-debugging
-build, the nodes aren't initialised to zero, and a 1-char EXACT node isn't
-long enough to spill into the type field of the "next node".
+=item C<sv_compile_2op>
-Fix this by only using NEXTOPER(first) when we know the first node is
-kosher.
+The C<sv_compile_2op()> API function is now deprecated. Searches suggest
+that nothing on CPAN is using it, so this should have zero impact.
-=item *
+It attempted to provide an API to compile code down to an optree, but failed
+to bind correctly to lexicals in the enclosing scope. It's not possible to
+fix this problem within the constraints of its parameters and return value.
-Break out the generated function Perl_keywords() into F<keywords.c>, a new file. (26ea9e1)
+=item C<find_rundefsvoffset>
-As it and Perl_yylex() both need FEATURE_IS_ENABLED, feature_is_enabled() is
-no longer static, and the two macro definitions move from toke.c to perl.h
+The C<find_rundefsvoffset> function has been deprecated. It appeared that
+its design was insufficient for reliably getting the lexical C<$_> at
+run-time.
-Previously, one had to cut and paste the output of perl_keywords.pl into the
-middle of toke.c, and it was not clear that it was generated code.
+Use the new C<find_rundefsv> function or the C<UNDERBAR> macro
+instead. They directly return the right SV representing C<$_>, whether it's
+lexical or dynamic.
-=item *
+=item C<CALL_FPTR> and C<CPERLscope>
-A lot of tests have been ported from Test to Test::More, e.g. in
-3842ad6.
+Those are left from an old implementation of C<MULTIPLICITY> using C++ objects,
+which was removed in Perl 5.8. Nowadays these macros do exactly nothing, so
+they shouldn't be used anymore.
-=item *
+For compatibility, they are still defined for external C<XS> code. Only
+extensions defining C<PERL_CORE> must be updated now.
-Increase default PerlIO buffer size. (b83080d)
+=back
-The previous default size of a PerlIO buffer (4096 bytes) has been increased
-to the larger of 8192 bytes and your local BUFSIZ. Benchmarks show that doubling
-this decade-old default increases read and write performance in the neighborhood
-of 25% to 50% when using the default layers of perlio on top of unix. To choose
-a non-default size, such as to get back the old value or to obtain and even
-larger value, configure with:
+=head2 Other Internal Changes
- ./Configure -Accflags=-DPERLIOBUF_DEFAULT_BUFSIZ=N
+=head3 Stack unwinding
-where N is the desired size in bytes; it should probably be a multiple of
-your page size.
+The protocol for unwinding the C stack at the last stage of a C<die>
+has changed how it identifies the target stack frame. This now uses
+a separate variable C<PL_restartjmpenv>, where previously it relied on
+the C<blk_eval.cur_top_env> pointer in the C<eval> context frame that
+has nominally just been discarded. This change means that code running
+during various stages of Perl-level unwinding no longer needs to take
+care to avoid destroying the ghost frame.
-=back
+=head3 Scope stack entries
-=head1 Selected Bug Fixes
+The format of entries on the scope stack has been changed, resulting in a
+reduction of memory usage of about 10%. In particular, the memory used by
+the scope stack to record each active lexical variable has been halved.
-=over 4
+=head3 Memory allocation for pointer tables
-=item *
+Memory allocation for pointer tables has been changed. Previously
+C<Perl_ptr_table_store> allocated memory from the same arena system as
+C<SV> bodies and C<HE>s, with freed memory remaining bound to those arenas
+until interpreter exit. Now it allocates memory from arenas private to the
+specific pointer table, and that memory is returned to the system when
+C<Perl_ptr_table_free> is called. Additionally, allocation and release are
+both less CPU intensive.
-C<when(scalar){...}> no longer crashes, but produces a syntax error
-[perl #74114].
+=head3 C<UNDERBAR>
-=item *
+The C<UNDERBAR> macro now calls C<find_rundefsv>. C<dUNDERBAR> is now a
+noop but should still be used to ensure past and future compatibility.
-The C-level C<lex_stuff_pvn> function would sometimes cause a spurious
-syntax error on the last line of the file if it lacked a final semicolon
-[perl #74006].
+=head3 String comparison routines renamed
-=item *
+The ibcmp_* functions have been renamed and are now called foldEQ,
+foldEQ_locale and foldEQ_utf8. The old names are still available as
+macros.
-The regular expression engine no longer loops when matching
-C<"\N{LATIN SMALL LIGATURE FF}" =~ /f+/i> and similar expressions
-[perl #72998].
+=head3 C<chop> and C<chomp> implementations merged
-=item *
+The opcode bodies for C<chop> and C<chomp> and for C<schop> and C<schomp>
+have been merged. The implementation functions C<Perl_do_chop()> and
+C<Perl_do_chomp()>, never part of the public API, have been merged and
+moved to a static function in F<pp.c>. This shrinks the perl binary
+slightly, and should not affect any code outside the core (unless it is
+relying on the order of side effects when C<chomp> is passed a I<list> of
+values).
-A label right before a string eval (C<foo: eval $string>) no longer causes
-the label to be associated also with the first statement inside the eval
-[perl #74290] (5.12.1).
+=head1 Selected Bug Fixes
-=item *
+=head2 I/O
-Naming a deprecated character in \N{...} will not leak memory.
+=over 4
=item *
-FETCH is no longer called needlessly on some tied variables.
-
-=item *
+Perl no longer produces this warning:
-The trie runtime code should no longer allocate massive amounts of memory,
-fixing #74484.
+ $ perl -we 'open my $f, ">", \my $x; binmode $f, "scalar"'
+ Use of uninitialized value in binmode at -e line 1.
=item *
-Timely cleanup of SVs that are cloned into a new thread but then
-discovered to be orphaned (i.e. their owners are -not- cloned) (e42956)
+Opening a glob reference via C<< open $fh, "E<gt>", \*glob >> will no longer
+cause the glob to be corrupted when the filehandle is printed to. This would
+cause perl to crash whenever the glob's contents were accessed
+[perl #77492].
=item *
-Don't accidentally clone lexicals in scope within active stack frames in
-the parent when creating a child thread (RT #73086) (05d04d).
+PerlIO no longer crashes when called recursively, e.g., from a signal
+handler. Now it just leaks memory [perl #75556].
=item *
-Avoid loading feature.pm when 'no 5.13.2;' or similar is
-encountered (faee19).
+Most I/O functions were not warning for unopened handles unless the
+'closed' and 'unopened' warnings categories were both enabled. Now only
+C<use warnings 'unopened'> is necessary to trigger these warnings (as was
+always meant to be the case).
=item *
-Trap invalid use of SvIVX on SVt_REGEXP when assertions are on
-(e77da3)
+There have been several fixes to PerlIO layers:
-=item *
+When C<binmode FH, ":crlf"> pushes the C<:crlf> layer on top of the stack,
+it no longer enables crlf layers lower in the stack, to avoid unexpected
+results [perl #38456].
-Don't stamp on $DB::single, $DB::trace and $DB::signal if they
-already have values when $^P is assigned to (RT #72422) (4c0f30).
+Opening a file in C<:raw> mode now does what it advertises to do (first
+open the file, then binmode it), instead of simply leaving off the top
+layer [perl #80764].
-=item *
+The three layers C<:pop>, C<:utf8> and C<:bytes> didn't allow stacking when
+opening a file. For example
+this:
-chop now correctly handles perl's extended UTF-8 (RT #73246) (65ab92)
+ open FH, '>:pop:perlio', 'some.file' or die $!;
-=item *
+Would throw an error: "Invalid argument". This has been fixed in this
+release [perl #82484].
-Defer signal handling when shared SV locks are held to avoid
-deadlocks (RT #74868) (65c742).
+=back
-=item *
+=head2 Regular Expression Bug Fixes
-glob() no longer crashes when %File::Glob:: is empty and
-CORE::GLOBAL::glob isn't present (4984aa).
+=over
=item *
-perlbug now always permits the sender address to be changed
-before sending - if you were having trouble sending bug reports before
-now, this should fix it, we hope (e6eb90).
+The regular expression engine no longer loops when matching
+C<"\N{LATIN SMALL LIGATURE FF}" =~ /f+/i> and similar expressions
+[perl #72998] (5.12.1).
=item *
-Overloading now works properly in conjunction with tied
-variables. What formerly happened was that most ops checked their
-arguments for overloading I<before> checking for magic, so for example
-an overloaded object returned by a tied array access would usually be
-treated as not overloaded (RT #57012) (6f1401, ed3b9b, 6a5f8c .. 24328f).
+The trie runtime code should no longer allocate massive amounts of memory,
+fixing #74484.
=item *
-Independently, a bug was fixed that prevented $tied-E<gt>() from
-always calling FETCH correctly (RT #8438) (7c7501)
+Syntax errors in C<< (?{...}) >> blocks no longer cause panic messages
+[perl #2353].
=item *
-Some work has been done on the internal pointers that link between symbol
-tables (stashes), typeglobs and subroutines. This has the effect that
-various edge cases related to deleting stashes or stash entries (e.g.
-<%FOO:: = ()>), and complex typeglob or code reference aliasing, will no
-longer crash the interpreter.
+A pattern like C<(?:(o){2})?> no longer causes a "panic" error
+[perl #39233].
=item *
-Fixed readline() when interrupted by signals so it no longer returns
-the "same thing" as before or random memory
+A fatal error in regular expressions containing C<(.*?)> when processing
+UTF-8 data has been fixed [perl #75680] (5.12.2).
=item *
-Fixed a regression of kill() when a match variable is used for the
-process ID to kill (RT#75812) (8af710e)
+An erroneous regular expression engine optimisation that caused regex verbs like
+C<*COMMIT> sometimes to be ignored has been removed.
=item *
-Fixed several subtle bugs in sort() when @_ is accessed within a subroutine
-used for sorting (RT#72334) (8f443ca)
+The regular expression bracketed character class C<[\8\9]> was effectively the
+same as C<[89\000]>, incorrectly matching a NULL character. It also gave
+incorrect warnings that the C<8> and C<9> were ignored. Now C<[\8\9]> is the
+same as C<[89]> and gives legitimate warnings that C<\8> and C<\9> are
+unrecognized escape sequences, passed-through.
=item *
-Catch yyparse() exceptions in C<< (?{...}) >> (RT#2353) (634d691)
+A regular expression match in the right-hand side of a global substitution
+(C<s///g>) that is in the same scope will no longer cause match variables
+to have the wrong values on subsequent iterations. This can happen when an
+array or hash subscript is interpolated in the right-hand side, as in
+C<s|(.)|@a{ print($1), /./ }|g> [perl #19078].
=item *
-Avoid UTF-8 cache panics with offsets beyond a string (RT #75898) (3e2d381)
+Several cases in which characters in the Latin-1 non-ASCII range (0x80 to
+0xFF) used not to match themselves or used to match both a character class
+and its complement have been fixed. For instance, U+00E2 could match both
+C<\w> and C<\W> [perl #78464] [perl #18281] [perl #60156].
=item *
-Fixed POSIX::strftime memory leak (RT#73520) (c4bc4aa)
+Matching a Unicode character against an alternation containing characters
+that happened to match continuation bytes in the former's UTF8
+representation (C<qq{\x{30ab}} =~ /\xab|\xa9/>) would cause erroneous
+warnings [perl #70998].
=item *
-Doesn't set strict with C<no VERSION> if C<VERSION> is greater than 5.12
-(da8fb5d)
+The trie optimisation was not taking empty groups into account, preventing
+'foo' from matching C</\A(?:(?:)foo|bar|zot)\z/> [perl #78356].
=item *
-Avoids multiple FETCH/stringify on filetest ops (40c852d)
+A pattern containing a C<+> inside a lookahead would sometimes cause an
+incorrect match failure in a global match (e.g., C</(?=(\S+))/g>)
+[perl #68564].
=item *
-Fixed issue with string C<eval> not detecting taint of overloaded/tied
-arguments (RT #75716) (895b760)
+A regular expression optimisation would sometimes cause a match with a
+C<{n,m}> quantifier to fail when it should match [perl #79152].
=item *
-Fix potential crashes of string C<eval> when evaluating a object with
-overloaded stringification by creating a stringified copy when necessary
-(3e5c018)
+Case insensitive matching in regular expressions compiled under C<use
+locale> now works much more sanely when the pattern or
+target string is encoded internally in
+UTF8. Previously, under these conditions the localeness
+was completely lost. Now, code points above 255 are treated as Unicode,
+but code points between 0 and 255 are treated using the current locale
+rules, regardless of whether the pattern or the string is encoded in UTF8.
+The few case-insensitive matches that cross the 255/256 boundary are not
+allowed. For example, 0xFF does not caselessly match the character at
+0x178, LATIN CAPITAL LETTER Y WITH DIAERESIS, because 0xFF may not be
+LATIN SMALL LETTER Y in the current locale, and Perl has no way of
+knowing if that character even exists in the locale, much less what code
+point it is.
=item *
-Fixed bug where overloaded stringification could remove tainting
-(RT #75716) (a02ec77)
+The C<(?|...)> regular expression construct no longer crashes if the final
+branch has more sets of capturing parentheses than any other branch. This
+was fixed in Perl 5.10.1 for the case of a single branch, but that fix did
+not take multiple branches into account [perl #84746].
=item *
-Plugs more memory leaks in vms.c. (9e2bec0)
-
-=item *
+A bug has been fixed in the implementation of C<{...}> quantifiers in
+regular expressions that prevented the code block in
+C</((\w+)(?{ print $2 })){2}/> from seeing the C<$2> sometimes
+[perl #84294].
-Fix pthread include error for Time::Piece (e9f284c)
+=back
-=item *
+=head2 Syntax/Parsing Bugs
-A possible memory leak when using L<caller()|perlfunc/"caller EXPR"> to set
-C<@DB::args> has been fixed.
+=over
=item *
-Several memory leaks when loading XS modules were fixed.
+C<when(scalar){...}> no longer crashes, but produces a syntax error
+[perl #74114] (5.12.1).
=item *
-A panic in the regular expression optimizer has been fixed (RT#75762).
+A label right before a string eval (C<foo: eval $string>) no longer causes
+the label to be associated also with the first statement inside the eval
+[perl #74290] (5.12.1).
=item *
-Assignments to lvalue subroutines now honor copy-on-write behavior again, which
-has been broken since version 5.10.0 (RT#75656).
+The C<no 5.13.2;> form of C<no> no longer tries to turn on features or
+pragmata (i.e., strict) [perl #70075] (5.12.2).
=item *
-Assignments to glob copies now behave just like assignments to regular globs
-(RT#1804).
+C<BEGIN {require 5.12.0}> now behaves as documented, rather than behaving
+identically to C<use 5.12.0;>. Previously, C<require> in a C<BEGIN> block
+was erroneously executing the C<use feature ':5.12.0'> and
+C<use strict;> behaviour, which only C<use> was documented to
+provide [perl #69050].
=item *
-Within signal handlers, C<$!> is now implicitly localized.
+A regression introduced in Perl 5.12.0, making
+C<< my $x = 3; $x = length(undef) >> result in C<$x> set to C<3> has been
+fixed. C<$x> will now be C<undef> [perl #85508] (5.12.2).
=item *
-L<readline|perlfunc/"readline EXPR"> now honors C<< <> >> overloading on tied
-arguments.
+When strict 'refs' mode is off, C<%{...}> in rvalue context returns
+C<undef> if its argument is undefined. An optimisation introduced in perl
+5.12.0 to make C<keys %{...}> faster when used as a boolean did not take
+this into account, causing C<keys %{+undef}> (and C<keys %$foo> when
+C<$foo> is undefined) to be an error, which it should only be in strict
+mode [perl #81750].
=item *
-L<substr()|perlfunc/"substr EXPR,OFFSET,LENGTH,REPLACEMENT">,
-L<pos()|perlfunc/"index STR,SUBSTR,POSITION">, L<keys()|perlfunc/"keys HASH">,
-and L<vec()|perlfunc/"vec EXPR,OFFSET,BITS"> could, when used in combination
-with lvalues, result in leaking the scalar value they operate on, and cause its
-destruction to happen too late. This has now been fixed.
-
-=item *
+Constant-folding used to cause
-Building with C<PERL_GLOBAL_STRUCT>, which has been broken accidentally in
-5.13.3, now works again.
+ $text =~ ( 1 ? /phoo/ : /bear/)
-=item *
+to turn into
-A regression introduced in Perl 5.12.0, making
-C<< my $x = 3; $x = length(undef) >> result in C<$x> set to C<3> has been
-fixed. C<$x> will now be C<undef>.
+ $text =~ /phoo/
+
+at compile time. Now it correctly matches against C<$_> [perl #20444].
=item *
-A fatal error in regular expressions when processing UTF-8 data has been fixed [perl #75680].
+Parsing Perl code (either with string C<eval> or by loading modules) from
+within a C<UNITCHECK> block no longer causes the interpreter to crash
+[perl #70614].
=item *
-An erroneous regular expression engine optimization that caused regex verbs like
-C<*COMMIT> to sometimes be ignored has been removed.
+String evals no longer fail after 2 billion scopes have been
+compiled [perl #83364].
=item *
-The Perl debugger now also works in taint mode [perl #76872].
+The parser no longer hangs when encountering certain Unicode characters,
+such as U+387 [perl #74022].
=item *
-Several memory leaks in cloning and freeing threaded Perl interpreters have been
-fixed [perl #77352].
+Several contexts no longer allow a Unicode character to begin a word
+that should never begin words, for an example an accent that must follow
+another character previously could precede all other characters.
=item *
-A possible string corruption when doing regular expression matches on overloaded
-objects has been fixed [perl #77084].
+Defining a constant with the same name as one of perl's special blocks
+(e.g., INIT) stopped working in 5.12.0, but has now been fixed
+[perl #78634].
=item *
-Magic applied to variables in the main package no longer affects other packages.
-See L</Magic variables outside the main package> above [perl #76138].
+A reference to a literal value used as a hash key (C<$hash{\"foo"}>) used
+to be stringified, even if the hash was tied [perl #79178].
=item *
-Opening a glob reference via C<< open $fh, "E<gt>", \*glob >> will no longer
-cause the glob to be corrupted when the filehandle is printed to. This would
-cause perl to crash whenever the glob's contents were accessed
-[perl #77492].
+A closure containing an C<if> statement followed by a constant or variable
+is no longer treated as a constant [perl #63540].
=item *
-The postincrement and postdecrement operators, C<++> and C<-->, used to cause
-leaks when being used on references. This has now been fixed.
+C<state> can now be used with attributes. It used to mean the same thing as
+C<my> if attributes were present [perl #68658].
=item *
-A bug when replacing the glob of a loop variable within the loop has been fixed
-[perl #21469]. This
-means the following code will no longer crash:
-
- for $x (...) {
- *x = *y;
- }
+Expressions like C<< @$a > 3 >> no longer cause C<$a> to be mentioned in
+the "Use of uninitialized value in numeric gt" warning when C<$a> is
+undefined (since it is not part of the C<E<gt>> expression, but the operand
+of the C<@>) [perl #72090].
=item *
-Perl would segfault if the undocumented C<Internals> functions that used
-reference prototypes were called with the C<&foo()> syntax, e.g.
-C<&Internals::SvREADONLY(undef)> [perl #77776].
+Accessing an element of a package array with a hard-coded number (as
+opposed to an arbitrary expression) would crash if the array did not exist.
+Usually the array would be autovivified during compilation, but typeglob
+manipulation could remove it, as in these two cases which used to crash:
-These functions now call C<SvROK> on their arguments before dereferencing them
-with C<SvRV>, and we test for this case in F<t/lib/universal.t>.
+ *d = *a; print $d[0];
+ undef *d; print $d[0];
=item *
-When assigning a list with duplicated keys to a hash, the assignment used to
-return garbage and/or freed values:
-
- @a = %h = (list with some duplicate keys);
-
-This has now been fixed [perl #31865].
+The C<-C> command line option, when used on the shebang line, can now be
+followed by other options [perl #72434].
=item *
-An earlier release of the 5.13 series of Perl changed the semantics of opening a
-reference to a copy of a glob:
+The C<B> module was returning C<B::OP>s instead of C<B::LOGOP>s for C<entertry> [perl #80622].
+This was due to a bug in the perl core, not in C<B> itself.
- my $var = *STDOUT;
- open my $fh, '>', \$var;
+=back
-This was a mistake, and the previous behaviour from Perl 5.10 and 5.12, which is
-to treat \$var as a scalar reference, has now been restored.
+=head2 Stashes, Globs and Method Lookup
-=item *
+Perl 5.10.0 introduced a new internal mechanism for caching MROs (method
+resolution orders, or lists of parent classes; aka "isa" caches) to make
+method lookup faster (so @ISA arrays would not have to be searched
+repeatedly). Unfortunately, this brought with it quite a few bugs. Almost
+all of these have been fixed now, along with a few MRO-related bugs that
+existed before 5.10.0:
-The regular expression bracketed character class C<[\8\9]> was effectively the
-same as C<[89\000]>, incorrectly matching a NULL character. It also gave
-incorrect warnings that the C<8> and C<9> were ignored. Now C<[\8\9]> is the
-same as C<[89]> and gives legitimate warnings that C<\8> and C<\9> are
-unrecognized escape sequences, passed-through.
+=over
=item *
-C<warn()> and C<die()> now respect utf8-encoded scalars [perl #45549].
-
-=item *
+The following used to have erratic effects on method resolution, because
+the "isa" caches were not reset or otherwise ended up listing the wrong
+classes. These have been fixed.
-A regular expression match in the right-hand side of a global substitution
-(C<s///g>) that is in the same scope will no longer cause match variables
-to have the wrong values on subsequent iterations. This can happen when an
-array or hash subscript is interpolated in the right-hand side, as in
-C<s|(.)|@a{ print($1), /./ }|g> [perl #19078].
+=over
-=item *
+=item Aliasing packages by assigning to globs [perl #77358]
-Constant-folding used to cause
+=item Deleting packages by deleting their containing stash elements
- $text =~ ( 1 ? /phoo/ : /bear/)
+=item Undefining the glob containing a package (C<undef *Foo::>)
-to turn into
+=item Undefining an ISA glob (C<undef *Foo::ISA>)
- $text =~ /phoo/
+=item Deleting an ISA stash element (C<delete $Foo::{ISA}>)
-at compile time. Now it correctly matches against C<$_> [perl #20444].
+=item Sharing @ISA arrays between classes (via C<*Foo::ISA = \@Bar::ISA> or
+C<*Foo::ISA = *Bar::ISA>) [perl #77238]
-=item *
+=back
-Parsing Perl code (either with string C<eval> or by loading modules) from
-within a C<UNITCHECK> block no longer causes the interpreter to crash
-[perl #70614].
+C<undef *Foo::ISA> would even stop a new C<@Foo::ISA> array from updating
+caches.
=item *
-When C<-d> is used on the shebang (C<#!>) line, the debugger now has access
-to the lines of the main program. In the past, this sometimes worked and
-sometimes did not, depending on what order things happened to be arranged
-in memory [perl #71806].
+Typeglob assignments would crash if the glob's stash no longer existed, so
+long as the glob assigned to was named 'ISA' or the glob on either side of
+the assignment contained a subroutine.
=item *
-The C<y///> or C<tr///> operator now calls get-magic (e.g., the C<FETCH>
-method of a tie) on its left-hand side just once, not twice [perl #76814].
+C<PL_isarev>, which is accessible to Perl via C<mro::get_isarev> is now
+updated properly when packages are deleted or removed from the C<@ISA> of
+other classes. This allows many packages to be created and deleted without
+causing a memory leak [perl #75176].
-=item *
+=back
-String comparison (C<eq>, C<ne>, C<lt>, C<gt>, C<le>, C<ge> and
-C<cmp>) and logical not (C<not> and C<!>) operators no longer call magic
-(e.g., tie methods) twice on their operands [perl #76814].
+In addition, various other bugs related to typeglobs and stashes have been
+fixed:
-This bug was introduced in an earlier 5.13 release, and does not affect
-perl 5.12.
+=over
=item *
-When a tied (or other magic) variable is used as, or in, a regular
-expression, it no longer has its C<FETCH> method called twice
-[perl #76814].
+Some work has been done on the internal pointers that link between symbol
+tables (stashes), typeglobs and subroutines. This has the effect that
+various edge cases related to deleting stashes or stash entries (e.g.
+<%FOO:: = ()>), and complex typeglob or code reference aliasing, will no
+longer crash the interpreter.
-This bug was introduced in an earlier 5.13 release, and does not affect
-perl 5.12.
+=item *
+
+Assigning a reference to a glob copy now assigns to a glob slot instead of
+overwriting the glob with a scalar [perl #1804] [perl #77508].
=item *
-The C<-C> command line option can now be followed by other options
-[perl #72434].
+A bug when replacing the glob of a loop variable within the loop has been fixed
+[perl #21469]. This
+means the following code will no longer crash:
+
+ for $x (...) {
+ *x = *y;
+ }
=item *
=item *
-Creating a new thread when directory handles were open used to cause a
-crash, because the handles were not cloned, but simply passed to the new
-thread, resulting in a double free.
-
-Now directory handles are cloned properly, on systems that have a C<fchdir>
-function. On other systems, new threads simply do not inherit directory
-handles from their parent threads [perl #75154].
+When trying to report C<Use of uninitialized value $Foo::BAR>, crashes could
+occur if the glob holding the global variable in question had been detached
+from its original stash by, for example, C<delete $::{'Foo::'}>. This has
+been fixed by disabling the reporting of variable names in those
+cases.
=item *
-The regular expression parser no longer hangs when parsing C<\18> and
-C<\88>.
+During the restoration of a localised typeglob on scope exit, any
+destructors called as a result would be able to see the typeglob in an
+inconsistent state, containing freed entries, which could result in a
+crash. This would affect code like this:
-This bug was introduced in version 5.13.5 and did not affect earlier
-versions [perl #78058].
+ local *@;
+ eval { die bless [] }; # puts an object in $@
+ sub DESTROY {
+ local $@; # boom
+ }
-=item *
+Now the glob entries are cleared before any destructors are called. This
+also means that destructors can vivify entries in the glob. So perl tries
+again and, if the entries are re-created too many times, dies with a
+'panic: gp_free...' error message.
-Subroutine redefinition works once more in the debugger [perl #48332].
+=back
-=item *
+=head2 Unicode
-The C<&> C<|> C<^> bitwise operators no longer coerce read-only arguments
-[perl #20661].
+=over
=item *
-Stringifying a scalar containing -0.0 no longer has the affect of turning
-false into true [perl #45133].
+What has become known as the "Unicode Bug" is mostly resolved in this release.
+Under C<use feature 'unicode_strings'>, the internal storage format of a
+string no longer affects the external semantics. There are two known
+exceptions. User-defined case changing functions, which are planned to
+be deprecated in 5.14, require utf8-encoded strings to function; and the
+character C<LATIN SMALL LETTER SHARP S> in regular expression
+case-insensitive matching has a somewhat different set of bugs depending
+on the internal storage format. Case-insensitive matching of all
+characters that have multi-character matches, as this one does, is
+problematical in Perl [perl #58182].
=item *
-Aliasing packages by assigning to globs or deleting packages by deleting
-their containing stash elements used to have erratic effects on method
-resolution, because the internal 'isa' caches were not reset. This has been
-fixed.
+The handling of Unicode non-characters has changed.
+Previously they were mostly considered illegal, except that only one of
+the 66 of them was known about in places. The Unicode standard
+considers them legal, but forbids the "open interchange" of them.
+This is part of the change to allow the internal use of any code point
+(see L</Core Enhancements>). Together, these changes resolve
+[perl #38722], [perl #51918], [perl #51936], [perl #63446].
=item *
-C<sort> with a custom sort routine could crash if too many nested
-subroutine calls occurred from within the sort routine [perl #77930].
-
-This bug was introduced in an earlier 5.13 release, and did not affect
-perl 5.12.
+Naming a deprecated character in \N{...} no longer leaks memory.
=item *
-The C<eval_sv> and C<eval_pv> C functions now set C<$@> correctly when
-there is a syntax error and no C<G_KEEPERR> flag, and never set it if the
-C<G_KEEPERR> flag is present [perl #3719].
+We fixed a bug that could cause \N{} constructs followed by a single . to
+be parsed incorrectly [perl #74978] (5.12.1).
=item *
-Nested C<map> and C<grep> blocks no longer leak memory when processing
-large lists [perl #48004].
+C<chop> now correctly handles characters above "\x{7fffffff}"
+[perl #73246].
=item *
-Malformed C<version> objects no longer cause crashes [perl #78286].
+Passing to C<index> an offset beyond the end of the string when the string
+is encoded internally in UTF8 no longer causes panics [perl #75898].
=item *
-The interpreter no longer crashes when freeing deeply-nested arrays of
-arrays. Hashes have not been fixed yet [perl #44225].
+C<warn()> and C<die()> now respect utf8-encoded scalars [perl #45549].
=item *
-The mechanism for freeing objects in globs used to leave dangling
-pointers to freed SVs, meaning Perl users could see corrupted state
-during destruction.
+Sometimes the UTF8 length cache would not be reset on a value
+returned by substr, causing C<length(substr($uni_string,...))> to give
+wrong answers. With C<${^UTF8CACHE}> set to -1, it would produce a 'panic'
+error message, too [perl #77692].
-Perl now only frees the affected slots of the GV, rather than freeing
-the GV itself. This makes sure that there are no dangling refs or
-corrupted state during destruction.
+=back
-=item *
+=head2 Ties, Overloading and Other Magic
-The typeglob C<*,>, which holds the scalar variable C<$,> (output field
-separator), had the wrong reference count in child threads.
+=over
=item *
-C<splice> now calls set-magic. This means that, for instance, changes made
-by C<splice @ISA> are respected by method calls [perl #78400].
+Overloading now works properly in conjunction with tied
+variables. What formerly happened was that most ops checked their
+arguments for overloading I<before> checking for magic, so for example
+an overloaded object returned by a tied array access would usually be
+treated as not overloaded [RT #57012].
=item *
-C<use v5.8> no longer leaks memory [perl #78436].
+Various cases of magic (e.g., tie methods) being called on tied variables
+too many or too few times have been fixed:
+
+=over
=item *
-The XS multicall API no longer causes subroutines to lose reference counts
-if called via the multicall interface from within those very subroutines.
-This affects modules like List::Util. Calling one of its functions with an
-active subroutine as the first argument could cause a crash [perl #78070].
+FETCH is no longer called on tied variables in void context.
=item *
-The C<parse_stmt> C function added in earlier in the 5.13.x series has been
-fixed to work with statements ending with C<}> [perl #78222].
+C<$tied-E<gt>()> did not always call FETCH [perl #8438].
=item *
-The C<parse_fullstmt> C function added in 5.13.5 has been fixed to work
-when called while an expression is being parsed.
+Filetest operators and C<y///> and C<tr///> were calling FETCH too
+many times.
=item *
-Characters in the Latin-1 non-ASCII range (0x80 to 0xFF) used not to match
-themselves if the string happened to be UTF8-encoded internally, the
-regular expression was not, and the character in the regular expression was
-inside a repeated group (e.g.,
-C<Encode::decode_utf8("\303\200") =~ /(\xc0)+/>) [perl #78464].
+The C<=> operator used to ignore magic on its right-hand side if the
+scalar happened to hold a typeglob (if a typeglob was the last thing
+returned from or assigned to a tied scalar) [perl #77498].
=item *
-The C<(?d)> regular expression construct now overrides a previous C<(?u)>
-or C<use feature "unicode_string"> [perl #78508].
+Dereference operators used to ignore magic if the argument was a
+reference already (e.g., from a previous FETCH) [perl #72144].
=item *
-A memory leak in C<do "file">, introduced in perl 5.13.6, has been fixed
-[perl #78488].
+C<splice> now calls set-magic (so changes made
+by C<splice @ISA> are respected by method calls) [perl #78400].
=item *
-Various bugs related to typeglob dereferencing have been fixed. See
-L</Dereferencing typeglobs>, above.
+In-memory files created by C<open $fh, 'E<gt>' \$buffer> were not calling
+FETCH/STORE at all [perl #43789] (5.12.2).
+
+=back
=item *
-The C<SvPVbyte> function available to XS modules now calls magic before
-downgrading the SV, to avoid warnings about wide characters [perl #72398].
+String C<eval> now detects taintedness of overloaded or tied
+arguments [perl #75716].
=item *
-The C<=> operator used to ignore magic (e.g., tie methods) on its
-right-hand side if the scalar happened to hold a typeglob. This could
-happen if a typeglob was the last thing returned from or assigned to a tied
-scalar [perl #77498].
+String C<eval> and regular expression matches against objects with string
+overloading no longer cause memory corruption or crashes [perl 77084].
=item *
-C<sprintf> was ignoring locales when called with constant arguments
-[perl #78632].
+L<readline|perlfunc/"readline EXPR"> now honors C<< <> >> overloading on tied
+arguments.
=item *
-A non-ASCII character in the Latin-1 range could match both a Posix
-class, such as C<[[:alnum:]]>, and its inverse C<[[:^alnum:]]>. This is
-now fixed for regular expressions compiled under the C<"u"> modifier.
-See L</C<use feature "unicode_strings"> now applies to more regex matching>. [perl #18281].
+C<< E<lt>exprE<gt> >> always respects overloading now if the expression is
+overloaded.
+
+Due to the way that 'E<lt>E<gt> as glob' was parsed differently from
+'E<lt>E<gt> as filehandle' from 5.6 onwards, something like C<< E<lt>$foo[0]E<gt> >> did
+not handle overloading, even if C<$foo[0]> was an overloaded object. This
+was contrary to the documentation for overload, and meant that C<< E<lt>E<gt> >>
+could not be used as a general overloaded iterator operator.
=item *
-Concatenating long strings under C<use encoding> no longer causes perl to
-crash [perl #78674].
+The fallback behaviour of overloading on binary operators was asymmetric
+[perl #71286].
=item *
-Typeglob assignments would crash if the glob's stash no longer existed, so
-long as the glob assigned to was named 'ISA' or the glob on either side of
-the assignment contained a subroutine.
+Magic applied to variables in the main package no longer affects other packages.
+See L</Magic variables outside the main package> above [perl #76138].
=item *
-Calling C<< ->import >> on a class lacking an import method could corrupt
-the stack, resulting in strange behaviour. For instance,
+Sometimes magic (ties, taintedness, etc.) attached to variables could cause
+an object to last longer than it should, or cause a crash if a tied
+variable were freed from within a tie method. These have been fixed
+[perl #81230].
- push @a, "foo", $b = bar->import;
+=item *
-would assign 'foo' to C<$b> [perl #63790].
+DESTROY methods of objects implementing ties are no longer able to crash by
+accessing the tied variable through a weak reference [perl #86328].
=item *
-Creating an alias to a package when that package had been detached from the
-symbol table would result in corrupted isa caches [perl #77358].
+Fixed a regression of kill() when a match variable is used for the
+process ID to kill [perl #75812].
=item *
-C<.=> followed by C<< <> >> or C<readline> would leak memory if C<$/>
-contained characters beyond the octet range and the scalar assigned to
-happened to be encoded as UTF8 internally [perl #72246].
+C<$AUTOLOAD> used to remain tainted forever if it ever became tainted. Now
+it is correctly untainted if an autoloaded method is called and the method
+name was not tainted.
=item *
-The C<recv> function could crash when called with the MSG_TRUNC flag
-[perl #75082].
+C<sprintf> now dies when passed a tainted scalar for the format. It did
+already die for arbitrary expressions, but not for simple scalars
+[perl #82250].
=item *
-Evaluating a simple glob (like C<*a>) was calling get-magic on the glob,
-even when its contents were not being used [perl #78580].
+utf8::is_utf8 now respects get-magic (e.g. $1) (5.12.1).
+
+=back
+
+=head2 The Debugger
-This bug was introduced in 5.13.2 and did not affect earlier perl versions.
+=over
=item *
-Matching a Unicode character against an alternation containing characters
-that happened to match continuation bytes in the former's UTF8
-representation (C<qq{\x{30ab}} =~ /\xab|\xa9/>) would cause erroneous
-warnings [perl #70998].
+The Perl debugger now also works in taint mode [perl #76872].
=item *
-C<s///r> (added in 5.13.2) no longer leaks.
+Subroutine redefinition works once more in the debugger [perl #48332].
=item *
-The trie optimisation was not taking empty groups into account, preventing
-'foo' from matching C</\A(?:(?:)foo|bar|zot)\z/> [perl #78356].
+When C<-d> is used on the shebang (C<#!>) line, the debugger now has access
+to the lines of the main program. In the past, this sometimes worked and
+sometimes did not, depending on what order things happened to be arranged
+in memory [perl #71806].
=item *
-A pattern containing a C<+> inside a lookahead would sometimes cause an
-incorrect match failure in a global match (e.g., C</(?=(\S+))/g>)
-[perl #68564].
+A possible memory leak when using L<caller()|perlfunc/"caller EXPR"> to set
+C<@DB::args> has been fixed (5.12.2).
=item *
-Iterating with C<foreach> over an array returned by an lvalue sub now works
-[perl #23790].
+Perl no longer stomps on $DB::single, $DB::trace and $DB::signal if they
+already have values when $^P is assigned to [perl #72422].
=item *
-C<$@> is now localised during calls to C<binmode> to prevent action at a
-distance [perl #78844].
+C<#line> directives in string evals were not properly updating the arrays
+of lines of code (C<< @{"_<..."} >>) that the debugger (or any debugging or
+profiling module) uses. In threaded builds, they were not being updated at
+all. In non-threaded builds, the line number was ignored, so any change to
+the existing line number would cause the lines to be misnumbered
+[perl #79442].
-=item *
+=back
-C<PL_isarev>, which is accessible to Perl via C<mro::get_isarev> is now
-updated properly when packages are deleted or removed from the C<@ISA> of
-other classes. This allows many packages to be created and deleted without
-causing a memory leak [perl #75176].
+=head2 Threads
+
+=over
=item *
-C<undef *Foo::> and C<undef *Foo::ISA> and C<delete $package::{ISA}>
-used not to update the internal isa caches if the
-stash or C<@ISA> array had a reference elsewhere. In
-fact, C<undef *Foo::ISA> would stop a new C<@Foo::ISA> array from updating
-caches.
+Perl no longer accidentally clones lexicals in scope within active stack
+frames in the parent when creating a child thread [perl #73086].
=item *
-C<@ISA> arrays can now be shared between classes via
-C<*Foo::ISA = \@Bar::ISA> or C<*Foo::ISA = *Bar::ISA> [perl #77238].
+Several memory leaks in cloning and freeing threaded Perl interpreters have been
+fixed [perl #77352].
=item *
-The parser no longer hangs when encountering certain Unicode characters,
-such as U+387 [perl #74022].
+Creating a new thread when directory handles were open used to cause a
+crash, because the handles were not cloned, but simply passed to the new
+thread, resulting in a double free.
+
+Now directory handles are cloned properly, on systems that have a C<fchdir>
+function. On other systems, new threads simply do not inherit directory
+handles from their parent threads [perl #75154].
=item *
-C<formline> no longer crashes when passed a tainted format picture. It also
-taints C<$^A> now if its arguments are tainted [perl #79138].
+The typeglob C<*,>, which holds the scalar variable C<$,> (output field
+separator), had the wrong reference count in child threads.
=item *
-A signal handler called within a signal handler could cause leaks or
-double-frees. Now fixed. [perl #76248].
+[perl #78494] When pipes are shared between threads, the C<close> function
+(and any implicit close, such as on thread exit) no longer blocks.
=item *
-When trying to report C<Use of uninitialized value $Foo::BAR>, crashes could
-occur if the GLOB of the global variable causing the warning has been detached
-from its original stash by, for example C<delete $::{'Foo::'}>. This has been
-fixed by disabling the reporting of variable names in the warning in those
-cases.
+Perl now does a timely cleanup of SVs that are cloned into a new thread but
+then discovered to be orphaned (i.e., their owners are I<not> cloned). This
+eliminates several "scalars leaked" warnings when joining threads.
-=item *
+=back
-C<BEGIN {require 5.12.0}> now behaves as documented, rather than behaving
-identically to C<use 5.12.0;>. Previously, C<require> in a C<BEGIN> block
-was erroneously executing the C<use feature ':5.12.0'> and
-C<use strict; use warnings;> behaviour, which only C<use> was documented to
-provide [perl #69050].
+=head2 Scoping and Subroutines
+
+=over
=item *
-C<use 5.42> [perl #69050],
-C<use 6> and C<no 5> no longer leak memory.
+Lvalue subroutines are again able to return copy-on-write scalars. This
+had been broken since version 5.10.0 [perl #75656] (5.12.3).
=item *
-C<eval "BEGIN{die}"> no longer leaks memory on non-threaded builds.
+C<require> no longer causes C<caller> to return the wrong file name for
+the scope that called C<require> and other scopes higher up that had the
+same file name [perl #68712].
=item *
-PerlIO no longer crashes when called recursively, e.g., from a signal
-handler. Now it just leaks memory [perl #75556].
+C<sort> with a ($$)-prototyped comparison routine used to cause the value
+of @_ to leak out of the sort. Taking a reference to @_ within the
+sorting routine could cause a crash [perl #72334].
=item *
-Defining a constant with the same name as one of perl's special blocks
-(e.g., INIT) stopped working in 5.12.0, but has now been fixed
-[perl #78634].
+Match variables (e.g., C<$1>) no longer persist between calls to a sort
+subroutine [perl #76026].
=item *
-A reference to a literal value used as a hash key (C<$hash{\"foo"}>) used
-to be stringified, even if the hash was tied [perl #79178].
+Iterating with C<foreach> over an array returned by an lvalue sub now works
+[perl #23790].
=item *
-A closure containing an C<if> statement followed by a constant or variable
-is no longer treated as a constant [perl #63540].
+C<$@> is now localised during calls to C<binmode> to prevent action at a
+distance [perl #78844].
=item *
=item *
-A regular expression optimisation would sometimes cause a match with a
-C<{n,m}> quantifier to fail when it should match [perl #79152].
+Mentioning a read-only lexical variable from the enclosing scope in a
+string C<eval> no longer causes the variable to become writable
+[perl #19135].
-=item *
+=back
-What has become known as the "Unicode Bug" is mostly resolved in this release.
-Under C<use feature 'unicode_strings'>, the internal storage format of a
-string no longer affects the external semantics. There are two known
-exceptions. User-defined case changing functions, which are planned to
-be deprecated in 5.14, require utf8-encoded strings to function; and the
-character C<LATIN SMALL LETTER SHARP S> in regular expression
-case-insensitive matching has a somewhat different set of bugs depending
-on the internal storage format. Case-insensitive matching of all
-characters that have multi-character matches, as this one does, is
-problematical in Perl [perl #58182].
+=head2 Signals
+
+=over
=item *
-Mentioning a read-only lexical variable from the enclosing scope in a
-string C<eval> no longer causes the variable to become writable
-[perl #19135].
+Within signal handlers, C<$!> is now implicitly localized.
=item *
-C<state> can now be used with attributes. It used to mean the same thing as
-C<my> if attributes were present [perl #68658].
+CHLD signals are no longer unblocked after a signal handler is called if
+they were blocked before by C<POSIX::sigprocmask> [perl #82040].
=item *
-Expressions like C<< @$a > 3 >> no longer cause C<$a> to be mentioned in
-the "Use of uninitialized value in numeric gt" warning when C<$a> is
-undefined (since it is not part of the C<E<gt>> expression, but the operand
-of the C<@>) [perl #72090].
+A signal handler called within a signal handler could cause leaks or
+double-frees. Now fixed. [perl #76248].
+
+=back
+
+=head2 Miscellaneous Memory Leaks
+
+=over
=item *
-C<require> no longer causes C<caller> to return the wrong file name for
-the scope that called C<require> and other scopes higher up that had the
-same file name [perl #68712].
+Several memory leaks when loading XS modules were fixed (5.12.2).
=item *
-The ref types in the typemap for XS bindings now support magical variables
-[perl #72684].
+L<substr()|perlfunc/"substr EXPR,OFFSET,LENGTH,REPLACEMENT">,
+L<pos()|perlfunc/"index STR,SUBSTR,POSITION">, L<keys()|perlfunc/"keys HASH">,
+and L<vec()|perlfunc/"vec EXPR,OFFSET,BITS"> could, when used in combination
+with lvalues, result in leaking the scalar value they operate on, and cause its
+destruction to happen too late. This has now been fixed.
=item *
-Match variables (e.g., C<$1>) no longer persist between calls to a sort
-subroutine [perl #76026].
+The postincrement and postdecrement operators, C<++> and C<-->, used to cause
+leaks when being used on references. This has now been fixed.
=item *
-The C<B> module was returning C<B::OP>s instead of C<B::LOGOP>s for C<entertry> [perl #80622].
-This was due to a bug in the perl core, not in C<B> itself.
+Nested C<map> and C<grep> blocks no longer leak memory when processing
+large lists [perl #48004].
=item *
-Some numeric operators were converting integers to floating point,
-resulting in loss of precision on 64-bit platforms [perl #77456].
+C<use I<VERSION>> and C<no I<VERSION>> no longer leak memory [perl #78436]
+[perl #69050].
=item *
-The fallback behaviour of overloading on binary operators was asymmetric
-[perl #71286].
+C<.=> followed by C<< <> >> or C<readline> would leak memory if C<$/>
+contained characters beyond the octet range and the scalar assigned to
+happened to be encoded as UTF8 internally [perl #72246].
=item *
-The handling of Unicode non-characters has changed.
-Previously they were mostly considered illegal, except that only one of
-the 66 of them was known about in places. The Unicode standard
-considers them legal, but forbids the "open interchange" of them.
-This is part of the change to allow the internal use of any code point
-(see L</Core Enhancements>). Together, these changes resolve
-[perl #38722], [perl #51918], [perl #51936], [perl #63446]
+C<eval "BEGIN{die}"> no longer leaks memory on non-threaded builds.
+
+=back
+
+=head2 Memory Corruption and Crashes
+
+=over
=item *
-Sometimes magic (ties, tainted, etc.) attached to variables could cause an
-object to last longer than it should, or cause a crash if a tied variable
-were freed from within a tie method. These have been fixed [perl #81230].
+glob() no longer crashes when %File::Glob:: is empty and
+CORE::GLOBAL::glob isn't present [perl #75464] (5.12.2).
=item *
-Most I/O functions were not warning for unopened handles unless the
-'closed' and 'unopened' warnings categories were both enabled. Now only
-C<use warnings 'unopened'> is necessary to trigger these warnings (as was
-always meant to be the case.
+readline() has been fixed when interrupted by signals so it no longer
+returns the "same thing" as before or random memory.
=item *
-C<< E<lt>exprE<gt> >> always respects overloading now if the expression is
-overloaded.
+When assigning a list with duplicated keys to a hash, the assignment used to
+return garbage and/or freed values:
-Due to the way that 'E<lt>E<gt> as glob' was parsed differently from
-'E<lt>E<gt> as filehandle' from 5.6 onwards, something like C<< E<lt>$foo[0]E<gt> >> did
-not handle overloading, even if C<$foo[0]> was an overloaded object. This
-was contrary to the documentation for overload, and meant that C<< E<lt>E<gt> >>
-could not be used as a general overloaded iterator operator.
+ @a = %h = (list with some duplicate keys);
+
+This has now been fixed [perl #31865].
=item *
-Destructors on objects were not called during global destruction on objects
-that were not referenced by any scalars. This could happen if an array
-element were blessed (e.g., C<bless \$a[0]>) or if a closure referenced a
-blessed variable (C<bless \my @a; sub foo { @a }>).
+The mechanism for freeing objects in globs used to leave dangling
+pointers to freed SVs, meaning Perl users could see corrupted state
+during destruction.
-Now there is an extra pass during global destruction to fire destructors on
-any objects that might be left after the usual passes that check for
-objects referenced by scalars
-[perl #36347].
+Perl now only frees the affected slots of the GV, rather than freeing
+the GV itself. This makes sure that there are no dangling refs or
+corrupted state during destruction.
=item *
-A long standing bug has now been fully fixed (partial fixes came in
-earlier releases), in which some Latin-1 non-ASCII characters on
-ASCII-platforms would match both a character class and its complement,
-such as U+00E2 being both in C<\w> and C<\W>, depending on the
-UTF-8-ness of the regular expression pattern and target string.
-Fixing this did expose some bugs in various modules and tests that
-relied on the previous behavior of C<[[:alpha:]]> not ever matching
-U+00FF, "LATIN SMALL LETTER Y WITH DIAERESIS", even when it should, in
-Unicode mode; now it does match when appropriate.
-[perl #60156].
+The interpreter no longer crashes when freeing deeply-nested arrays of
+arrays. Hashes have not been fixed yet [perl #44225].
=item *
-A Unicode C<\p{}> property match in a regular expression pattern will
-now force Unicode rules for the rest of the regular expression
+Concatenating long strings under C<use encoding> no longer causes perl to
+crash [perl #78674].
=item *
-[perl #38456] binmode FH, ":crlf" only modifies top crlf layer (7826b36)
+Calling C<< ->import >> on a class lacking an import method could corrupt
+the stack, resulting in strange behaviour. For instance,
+
+ push @a, "foo", $b = bar->import;
-When pushed on top of the stack, crlf will no longer enable crlf layers
-lower in the stack. This will prevent unexpected results.
+would assign 'foo' to C<$b> [perl #63790].
=item *
-Fix 'raw' layer for RT #80764 (ecfd064)
+The C<recv> function could crash when called with the MSG_TRUNC flag
+[perl #75082].
+
+=item *
-Made a ':raw' open do what it advertises to do (first open the file,
-then binmode it), instead of leaving off the top layer.
+C<formline> no longer crashes when passed a tainted format picture. It also
+taints C<$^A> now if its arguments are tainted [perl #79138].
=item *
-Use PerlIOBase_open for pop, utf8 and bytes layers (c0888ac)
+A bug in how we process filetest operations could cause a segfault.
+Filetests don't always expect an op on the stack, so we now use
+TOPs only if we're sure that we're not stat'ing the _ filehandle.
+This is indicated by OPf_KIDS (as checked in ck_ftst) [perl #74542]
+(5.12.1).
-Three of Perl's builtin PerlIO layers (C<:pop>, C<:utf8> and
-C<:bytes>) didn't allow stacking when opening a file. For example
-this:
+=item *
- open FH, '>:pop:perlio', 'some.file' or die $!;
+C<unpack()> now handles scalar context correctly for C<%32H> and C<%32u>,
+fixing a potential crash. C<split()> would crash because the third item
+on the stack wasn't the regular expression it expected. C<unpack("%2H",
+...)> would return both the unpacked result and the checksum on the stack,
+as would C<unpack("%2u", ...)> [perl #73814] (5.12.2).
-Would throw an error: "Invalid argument". This has been fixed in this
-release.
+=back
-=item *
+=head2 Fixes to Various Perl Operators
-An issue present since 5.13.1, where s/A/B/ with A utf8 and B
-non-utf8, could cause corruption or segfaults has been
-fixed. (c95ca9b)
+=over
=item *
-String evals will no longer fail after 2 billion scopes have been
-compiled (d1bfb64, 2df5bdd, 0d311cd and 6012dc8)
+The C<&> C<|> C<^> bitwise operators no longer coerce read-only arguments
+[perl #20661].
=item *
-[perl #81750] When strict 'refs' mode is off,
-C<%{...}> in rvalue context returns C<undef> if
-its argument is undefined. An optimisation introduced in perl 5.12.0 to
-make C<keys %{...}> faster when used as a boolean did not take this into
-account, causing C<keys %{+undef}> (and C<keys %$foo> when C<$foo> is
-undefined) to be an error, which it should only be in strict mode.
+Stringifying a scalar containing -0.0 no longer has the affect of turning
+false into true [perl #45133].
=item *
-[perl #83194] Combining the vector (%v) flag and dynamic precision would
-cause sprintf to confuse the order of its arguments, making it treat the
-string as the precision and vice versa.
+Some numeric operators were converting integers to floating point,
+resulting in loss of precision on 64-bit platforms [perl #77456].
=item *
-[perl #77692] Sometimes the UTF8 length cache would not be reset on a value
-returned by substr, causing C<length(substr($uni_string,...))> to give
-wrong answers. With C<${^UTF8CACHE}> set to -1, it would produce a 'panic'
-error message, too.
+C<sprintf> was ignoring locales when called with constant arguments
+[perl #78632].
=item *
-During the restoration of a localised typeglob on scope exit, any
-destructors called as a result would be able to see the typeglob in an
-inconsistent state, containing freed entries, which could result in a
-crash. This would affect code like this:
+Combining the vector (%v) flag and dynamic precision would
+cause sprintf to confuse the order of its arguments, making it treat the
+string as the precision and vice versa [perl #83194].
- local *@;
- eval { die bless [] }; # puts an object in $@
- sub DESTROY {
- local $@; # boom
- }
+=back
-Now the glob entries are cleared before any destructors are called. This
-also means that destructors can vivify entries in the glob. So perl tries
-again and, if the entries are re-created too many times, dies with a
-'panic: gp_free...' error message.
+=head2 Bugs Relating to the C API
+
+=over
=item *
-[perl #78494] When pipes are shared between threads, the C<close> function
-(and any implicit close, such as on thread exit) no longer blocks.
+The C-level C<lex_stuff_pvn> function would sometimes cause a spurious
+syntax error on the last line of the file if it lacked a final semicolon
+[perl #74006] (5.12.1).
=item *
-Several contexts no longer allow a Unicode character to begin a word
-that should never begin words, for an example an accent that must follow
-another character previously could precede all other characters.
+The C<eval_sv> and C<eval_pv> C functions now set C<$@> correctly when
+there is a syntax error and no C<G_KEEPERR> flag, and never set it if the
+C<G_KEEPERR> flag is present [perl #3719].
=item *
-Case insensitive matching in regular expressions compiled under C<use
-locale> now works much more sanely when the pattern and/or target string
-are encoded in UTF-8. Previously, under these conditions the localeness
-was completely lost. Now, code points above 255 are treated as Unicode,
-but code points between 0 and 255 are treated using the current locale
-rules, regardless of whether the pattern or string are encoded in UTF-8.
-The few case insensitive matches that cross the 255/256 boundary are not
-allowed. For example, 0xFF does not caselessly match the character at
-0x178, LATIN CAPITAL LETTER Y WITH DIAERESIS, because 0xFF may not be
-LATIN SMALL LETTER Y in the current locale, and Perl has no way of
-knowing if that character even exists in the locale, much less what code
-point it is.
+The XS multicall API no longer causes subroutines to lose reference counts
+if called via the multicall interface from within those very subroutines.
+This affects modules like List::Util. Calling one of its functions with an
+active subroutine as the first argument could cause a crash [perl #78070].
=item *
-A fix for a bug in C<length(undef)> in 5.13.4 introduced a regression that
-meant C<print length undef> did not warn when warnings were enabled. It now
-correctly warns [perl #85508].
+The C<SvPVbyte> function available to XS modules now calls magic before
+downgrading the SV, to avoid warnings about wide characters [perl #72398].
=item *
-The C<(?|...)> regular expression construct no longer crashes if the final
-branch has more sets of capturing parentheses than any other branch. This
-was fixed in Perl 5.10.1 for the case of a single branch, but that fix did
-not take multiple branches into account [perl #84746].
+The ref types in the typemap for XS bindings now support magical variables
+[perl #72684].
=item *
-Accessing an element of a package array with a hard-coded number (as
-opposed to an arbitrary expression) would crash if the array did not exist.
-Usually the array would be autovivified during compilation, but typeglob
-manipulation could remove it, as in these two cases which used to crash:
+C<sv_catsv_flags> no longer calls C<mg_get> on its second argument (the
+source string) if the flags passed to it do not include SV_GMAGIC. So it
+now matches the documentation.
- *d = *a; print $d[0];
- undef *d; print $d[0];
+=item *
+
+C<my_strftime> no longer leaks memory. This fixes a memory leak in
+C<POSIX::strftime> [perl #73520].
=item *
-C<#line> directives in string evals were not properly updating the arrays
-of lines of code (C<< @{"_<..."} >>) that the debugger (or any debugging or
-profiling module) uses. In threaded builds, they were not being updated at
-all. In non-threaded builds, the line number was ignored, so any change to
-the existing line number would cause the lines to be misnumbered
-[perl #79442].
+XSUB.h now correctly redefines fgets under PERL_IMPLICIT_SYS [perl #55049]
+(5.12.1).
=item *
-C<$AUTOLOAD> used to remain tainted forever if it ever became tainted. Now
-it is correctly untainted if an autoloaded method is called and the method
-name was not tainted.
+XS code using C<fputc()> or C<fputs()>: on Windows could cause an error
+due to their arguments being swapped [perl #72704] (5.12.1).
=item *
-A bug has been fixed in the implementation of C<{...}> quantifiers in
-regular expressions that prevented the code block in
-C</((\w+)(?{ print $2 })){2}/> from seeing the C<$2> sometimes
-[perl #84294].
+A possible segfault in the C<T_PRTOBJ> default typemap has been fixed
+(5.12.2).
=item *
-C<sprintf> now dies when passed a tainted scalar for the format. It did
-already die for arbitrary expressions, but not for simple scalars
-[perl #82250].
+A bug that could cause "Unknown error" messages when
+C<call_sv(code, G_EVAL)> is called from an XS destructor has been fixed
+(5.12.2).
=back
=head1 Known Problems
+XXX Many of these have probably already been solved. There are also
+unresolved BBC articles linked to #77718 that are awaiting CPAN
+releases. These may need to be listed here.
+See also #84444. Enbugger may also need to be listed if there is no new
+release in time (see #82152).
+JJORE/overload-eval-0.08.tar.gz appears to be broken, too. See
+http://www.nntp.perl.org/group/perl.perl5.porters/2010/11/msg165773.html
+
=over 4
=item *
-Bug fixes involving CvGV reference counting break Sub::Name. A
-patch has been sent upstream to the maintainer
+C<List::Util::first> misbehaves in the presence of a lexical C<$_>
+(typically introduced by C<my $_> or implicitly by C<given>). The variable
+which gets set for each iteration is the package variable C<$_>, not the
+lexical C<$_>.
+
+A similar issue may occur in other modules that provide functions which
+take a block as their first argument, like
+
+ foo { ... $_ ...} list
+
+See also: L<http://rt.perl.org/rt3/Public/Bug/Display.html?id=67694>
=item *
=head1 Errata
-=head2 C<keys>, C<values> work on arrays
+=head2 C<keys>, C<values> and C<each> work on arrays
You can now use the C<keys>, C<values>, C<each> builtin functions on arrays
(previously you could only use them on hashes). See L<perlfunc> for details.
https://perl5.git.perl.org / perl5.git / blobdiff