If you are upgrading from an earlier release such as 5.18.0, first read the perl5200delta manpage, which describes differences between 5.18.0 and 5.20.0.

Core Enhancements

New bitwise operators

A new experimental facility has been added that makes the four standard bitwise operators (& | ^ ~) treat their operands consistently as numbers, and introduces four new dotted operators (&. |. ^. ~.) that treat their operands consistently as strings. The same applies to the assignment variants (&= |= ^= &.= |.= ^.=).

To use this, enable the ``bitwise'' feature and disable the ``experimental::bitwise'' warnings category. See Bitwise String Operators in the perlop manpage for details. [perl #123466].

New double-diamond operator

<<>> is like <> but uses three-argument open to open each file in @ARGV. This means that each element of @ARGV will be treated as an actual file name, and "|foo" won't be treated as a pipe open.

New `\b` boundaries in regular expressions

`qr/\b{gcb}/`

gcb stands for Grapheme Cluster Boundary. It is a Unicode property that finds the boundary between sequences of characters that look like a single character to a native speaker of a language. Perl has long had the ability to deal with these through the \X regular escape sequence. Now, there is an alternative way of handling these. See \b{}, \b, \B{}, \B in the perlrebackslash manpage for details.

`qr/\b{wb}/`

wb stands for Word Boundary. It is a Unicode property that finds the boundary between words. This is similar to the plain \b (without braces) but is more suitable for natural language processing. It knows, for example, that apostrophes can occur in the middle of words. See \b{}, \b, \B{}, \B in the perlrebackslash manpage for details.

`qr/\b{sb}/`

sb stands for Sentence Boundary. It is a Unicode property to aid in parsing natural language sentences. See \b{}, \b, \B{}, \B in the perlrebackslash manpage for details.

Non-Capturing Regular Expression Flag

Regular expressions now support a /n flag that disables capturing and filling in $1, $2, etc inside of groups:

  "hello" =~ /(hi|hello)/n; # $1 is not set

This is equivalent to putting ?: at the beginning of every capturing group.

See n in the perlre manpage for more information.

`use re 'strict'`

This applies stricter syntax rules to regular expression patterns compiled within its scope. This will hopefully alert you to typos and other unintentional behavior that backwards-compatibility issues prevent us from reporting in normal regular expression compilations. Because the behavior of this is subject to change in future Perl releases as we gain experience, using this pragma will raise a warning of category experimental::re_strict. See 'strict' in re.

Unicode 7.0 (with correction) is now supported

For details on what is in this release, see http://www.unicode.org/versions/Unicode7.0.0/. The version of Unicode 7.0 that comes with Perl includes a correction dealing with glyph shaping in Arabic (see http://www.unicode.org/errata/#current_errata).

`use locale` can restrict which locale categories are affected

It is now possible to pass a parameter to use locale to specify a subset of locale categories to be locale-aware, with the remaining ones unaffected. See The ``use locale'' pragma in the perllocale manpage for details.

Perl now supports POSIX 2008 locale currency additions

On platforms that are able to handle POSIX.1-2008, the hash returned by POSIX::localeconv() includes the international currency fields added by that version of the POSIX standard. These are int_n_cs_precedes, int_n_sep_by_space, int_n_sign_posn, int_p_cs_precedes, int_p_sep_by_space, and int_p_sign_posn.

Better heuristics on older platforms for determining locale UTF-8ness

On platforms that implement neither the C99 standard nor the POSIX 2001 standard, determining if the current locale is UTF-8 or not depends on heuristics. These are improved in this release.

Aliasing via reference

Variables and subroutines can now be aliased by assigning to a reference:

    \$c = \$d;
    \&x = \&y;

Aliasing can also be accomplished by using a backslash before a foreach iterator variable; this is perhaps the most useful idiom this feature provides:

    foreach \%hash (@array_of_hash_refs) { ... }

This feature is experimental and must be enabled via use feature 'refaliasing'. It will warn unless the experimental::refaliasing warnings category is disabled.

See Assigning to References in the perlref manpage

`prototype` with no arguments

prototype() with no arguments now infers $_. [perl #123514].

New `:const` subroutine attribute

The const attribute can be applied to an anonymous subroutine. It causes the new sub to be executed immediately whenever one is created (i.e. when the sub expression is evaluated). Its value is captured and used to create a new constant subroutine that is returned. This feature is experimental. See Constant Functions in the perlsub manpage.

`fileno` now works on directory handles

When the relevant support is available in the operating system, the fileno builtin now works on directory handles, yielding the underlying file descriptor in the same way as for filehandles. On operating systems without such support, fileno on a directory handle continues to return the undefined value, as before, but also sets $! to indicate that the operation is not supported.

Currently, this uses either a dd_fd member in the OS DIR structure, or a dirfd(3) function as specified by POSIX.1-2008.

List form of pipe open implemented for Win32

The list form of pipe:

  open my $fh, "-|", "program", @arguments;

is now implemented on Win32. It has the same limitations as system LIST on Win32, since the Win32 API doesn't accept program arguments as a list.

Assignment to list repetition

(...) x ... can now be used within a list that is assigned to, as long as the left-hand side is a valid lvalue. This allows (undef,undef,$foo) = that_function() to be written as ((undef)x2, $foo) = that_function().

Infinity and NaN (not-a-number) handling improved

Floating point values are able to hold the special values infinity, negative infinity, and NaN (not-a-number). Now we more robustly recognize and propagate the value in computations, and on output normalize them to the strings Inf, -Inf, and NaN.

See also the the POSIX manpage enhancements.

Floating point parsing has been improved

Parsing and printing of floating point values has been improved.

As a completely new feature, hexadecimal floating point literals (like 0x1.23p-4) are now supported, and they can be output with printf "%a". See Scalar value constructors in the perldata manpage for more details.

Packing infinity or not-a-number into a character is now fatal

Before, when trying to pack infinity or not-a-number into a (signed) character, Perl would warn, and assumed you tried to pack 0xFF; if you gave it as an argument to chr, U+FFFD was returned.

But now, all such actions (pack, chr, and print '%c') result in a fatal error.

Experimental C Backtrace API

Perl now supports (via a C level API) retrieving the C level backtrace (similar to what symbolic debuggers like gdb do).

The backtrace returns the stack trace of the C call frames, with the symbol names (function names), the object names (like ``perl''), and if it can, also the source code locations (file:line).

The supported platforms are Linux and OS X (some *BSD might work at least partly, but they have not yet been tested).

The feature needs to be enabled with Configure -Dusecbacktrace.

See C backtrace in the perlhacktips manpage for more information.

Security

Perl is now compiled with `-fstack-protector-strong` if available

Perl has been compiled with the anti-stack-smashing option -fstack-protector since 5.10.1. Now Perl uses the newer variant called -fstack-protector-strong, if available.

The the Safe manpage module could allow outside packages to be replaced

Critical bugfix: outside packages could be replaced. the Safe manpage has been patched to 2.38 to address this.

Perl is now always compiled with `-D_FORTIFY_SOURCE=2` if available

The 'code hardening' option called _FORTIFY_SOURCE, available in gcc 4.*, is now always used for compiling Perl, if available.

Note that this isn't necessarily a huge step since in many platforms the step had already been taken several years ago: many Linux distributions (like Fedora) have been using this option for Perl, and OS X has enforced the same for many years.

Incompatible Changes

Subroutine signatures moved before attributes

The experimental sub signatures feature, as introduced in 5.20, parsed signatures after attributes. In this release, following feedback from users of the experimental feature, the positioning has been moved such that signatures occur after the subroutine name (if any) and before the attribute list (if any).

`&` and `\&` prototypes accepts only subs

The & prototype character now accepts only anonymous subs (sub {...}), things beginning with \&, or an explicit undef. Formerly it erroneously also allowed references to arrays, hashes, and lists. [perl #4539]. [perl #123062]. [perl #123062].

In addition, the \& prototype was allowing subroutine calls, whereas now it only allows subroutines: &foo is still permitted as an argument, while &foo() and foo() no longer are. [perl #77860].

`use encoding` is now lexical

The the encoding manpage pragma's effect is now limited to lexical scope. This pragma is deprecated, but in the meantime, it could adversely affect unrelated modules that are included in the same program; this change fixes that.

List slices returning empty lists

List slices now return an empty list only if the original list was empty (or if there are no indices). Formerly, a list slice would return an empty list if all indices fell outside the original list; now it returns a list of undef values in that case. [perl #114498].

`\N{}` with a sequence of multiple spaces is now a fatal error

E.g. \N{TOOMANY SPACES} or \N{TRAILING SPACE }. This has been deprecated since v5.18.

`use UNIVERSAL '...'` is now a fatal error

Importing functions from UNIVERSAL has been deprecated since v5.12, and is now a fatal error. use UNIVERSAL without any arguments is still allowed.

In double-quotish `\cX`, X must now be a printable ASCII character

In prior releases, failure to do this raised a deprecation warning.

Splitting the tokens `(?` and `(*` in regular expressions is now a fatal compilation error.

These had been deprecated since v5.18.

`qr/foo/x` now ignores all Unicode pattern white space

The /x regular expression modifier allows the pattern to contain white space and comments (both of which are ignored) for improved readability. Until now, not all the white space characters that Unicode designates for this purpose were handled. The additional ones now recognized are:

    U+0085 NEXT LINE
    U+200E LEFT-TO-RIGHT MARK
    U+200F RIGHT-TO-LEFT MARK
    U+2028 LINE SEPARATOR
    U+2029 PARAGRAPH SEPARATOR

The use of these characters with /x outside bracketed character classes and when not preceded by a backslash has raised a deprecation warning since v5.18. Now they will be ignored.

Comment lines within `(?[ ])` are now ended only by a `\n`

(?[ ]) is an experimental feature, introduced in v5.18. It operates as if /x is always enabled. But there was a difference: comment lines (following a # character) were terminated by anything matching \R which includes all vertical whitespace, such as form feeds. For consistency, this is now changed to match what terminates comment lines outside (?[ ]), namely a \n (even if escaped), which is the same as what terminates a heredoc string and formats.

`(?[...])` operators now follow standard Perl precedence

This experimental feature allows set operations in regular expression patterns. Prior to this, the intersection operator had the same precedence as the other binary operators. Now it has higher precedence. This could lead to different outcomes than existing code expects (though the documentation has always noted that this change might happen, recommending fully parenthesizing the expressions). See Extended Bracketed Character Classes in the perlrecharclass manpage.

Omitting `%` and `@` on hash and array names is no longer permitted

Really old Perl let you omit the @ on array names and the % on hash names in some spots. This has issued a deprecation warning since Perl 5.000, and is no longer permitted.

`"$!"` text is now in English outside the scope of `use locale`

Previously, the text, unlike almost everything else, always came out based on the current underlying locale of the program. (Also affected on some systems is "$^E".) For programs that are unprepared to handle locale differences, this can cause garbage text to be displayed. It's better to display text that is translatable via some tool than garbage text which is much harder to figure out.

`"$!"` text will be returned in UTF-8 when appropriate

The stringification of $! and $^E will have the UTF-8 flag set when the text is actually non-ASCII UTF-8. This will enable programs that are set up to be locale-aware to properly output messages in the user's native language. Code that needs to continue the 5.20 and earlier behavior can do the stringification within the scopes of both use bytes and use locale ":messages". Within these two scopes, no other Perl operations will be affected by locale; only $! and $^E stringification. The bytes pragma causes the UTF-8 flag to not be set, just as in previous Perl releases. This resolves [perl #112208].

Support for `?PATTERN?` without explicit operator has been removed

The m?PATTERN? construct, which allows matching a regex only once, previously had an alternative form that was written directly with a question mark delimiter, omitting the explicit m operator. This usage has produced a deprecation warning since 5.14.0. It is now a syntax error, so that the question mark can be available for use in new operators.

`defined(@array)` and `defined(%hash)` are now fatal errors

These have been deprecated since v5.6.1 and have raised deprecation warnings since v5.16.

Using a hash or an array as a reference are now fatal errors

For example, %foo->{"bar"} now causes a fatal compilation error. These have been deprecated since before v5.8, and have raised deprecation warnings since then.

Changes to the `*` prototype

The * character in a subroutine's prototype used to allow barewords to take precedence over most, but not all, subroutine names. It was never consistent and exhibited buggy behavior.

Now it has been changed, so subroutines always take precedence over barewords, which brings it into conformity with similarly prototyped built-in functions:

    sub splat(*) { ... }
    sub foo { ... }
    splat(foo); # now always splat(foo())
    splat(bar); # still splat('bar') as before
    close(foo); # close(foo())
    close(bar); # close('bar')

Deprecations

Setting `${^ENCODING}` to anything but `undef`

This variable allows Perl scripts to be written in an encoding other than ASCII or UTF-8. However, it affects all modules globally, leading to wrong answers and segmentation faults. New scripts should be written in UTF-8; old scripts should be converted to UTF-8, which is easily done with the piconv utility.

Use of non-graphic characters in single-character variable names

The syntax for single-character variable names is more lenient than for longer variable names, allowing the one-character name to be a punctuation character or even invisible (a non-graphic). Perl v5.20 deprecated the ASCII-range controls as such a name. Now, all non-graphic characters that formerly were allowed are deprecated. The practical effect of this occurs only when not under use utf8>, and affects just the C1 controls (code points 0x80 through 0xFF), NO-BREAK SPACE, and SOFT HYPHEN.

Inlining of `sub () { $var }` with observable side-effects

In many cases Perl makes sub () { $var } into an inlinable constant subroutine, capturing the value of $var at the time the sub expression is evaluated. This can break the closure behavior in those cases where $var is subsequently modified, since the subroutine won't return the changed value. (Note that this all only applies to anonymous subroutines with an empty prototype (sub ()).)

This usage is now deprecated in those cases where the variable could be modified elsewhere. Perl detects those cases and emits a deprecation warning. Such code will likely change in the future and stop producing a constant.

If your variable is only modified in the place where it is declared, then Perl will continue to make the sub inlinable with no warnings.

    sub make_constant {
        my $var = shift;
        return sub () { $var }; # fine
    }

    sub make_constant_deprecated {
        my $var;
        $var = shift;
        return sub () { $var }; # deprecated
    }

    sub make_constant_deprecated2 {
        my $var = shift;
        log_that_value($var); # could modify $var
        return sub () { $var }; # deprecated
    }

In the second example above, detecting that $var is assigned to only once is too hard to detect. That it happens in a spot other than the my declaration is enough for Perl to find it suspicious.

This deprecation warning happens only for a simple variable for the body of the sub. (A BEGIN block or use statement inside the sub is ignored, because it does not become part of the sub's body.) For more complex cases, such as sub () { do_something() if 0; $var } the behavior has changed such that inlining does not happen if the variable is modifiable elsewhere. Such cases should be rare.

Use of multiple `/x` regexp modifiers

It is now deprecated to say something like any of the following:

    qr/foo/xx;
    /(?xax:foo)/;
    use re qw(/amxx);

That is, now x should only occur once in any string of contiguous regular expression pattern modifiers. We do not believe there are any occurrences of this in all of CPAN. This is in preparation for a future Perl release having /xx permit white-space for readability in bracketed character classes (those enclosed in square brackets: [...]).

Using a NO-BREAK space in a character alias for `\N{...}` is now deprecated

This non-graphic character is essentially indistinguishable from a regular space, and so should not be allowed. See CUSTOM ALIASES in the charnames manpage.

A literal `"{"` should now be escaped in a pattern

If you want a literal left curly bracket (also called a left brace) in a regular expression pattern, you should now escape it by either preceding it with a backslash ("\{") or enclosing it within square brackets "[{]", or by using \Q; otherwise a deprecation warning will be raised. This was first announced as forthcoming in the v5.16 release; it will allow future extensions to the language to happen.

Making all warnings fatal is discouraged

The documentation for fatal warnings notes that use warnings FATAL => 'all' is discouraged, and provides stronger language about the risks of fatal warnings in general.

Performance Enhancements

SUPER::new

Internal Changes

(...)x1

("constant")x0

($scalar)x0

(foo())x0

substr

return

"\L..."

"\Q..."

lcfirst

quotemeta

FETCH

length

use bytes

@array = split

split

@_

join

join "-", "a", "b"

"a-b"

join

qq(@array)

qq

our $var

our($s,@a,%h) in void context are no longer evaluated at run time. Even a whole sequence of our $foo; statements will simply be skipped over. The same applies to state variables.

Many internal functions have been refactored to improve performance and reduce their memory footprints. [perl #121436] [perl #121906] [perl #121969]

-T and -B filetests will return sooner when an empty file is detected. [perl #121489]

Hash lookups where the key is a constant are faster.

Subroutines with an empty prototype and a body containing just undef are now eligible for inlining. [perl #122728]

Subroutines in packages no longer need to be stored in typeglobs: declaring a subroutine will now put a simple sub reference directly in the stash if possible, saving memory. The typeglob still notionally exists, so accessing it will cause the stash entry to be upgraded to a typeglob (i.e. this is just an internal implementation detail). This optimization does not currently apply to XSUBs or exported subroutines, and method calls will undo it, since they cache things in typeglobs. [perl #120441]

The functions utf8::native_to_unicode() and utf8::unicode_to_native() (see the utf8 manpage) are now optimized out on ASCII platforms. There is now not even a minimal performance hit in writing code portable between ASCII and EBCDIC platforms.

Win32 Perl uses 8 KB less of per-process memory than before for every perl process, because some data is now memory mapped from disk and shared between processes from the same perl binary.

Modules and Pragmata

Updated Modules and Pragmata

Many of the libraries distributed with perl have been upgraded since v5.20.0. For a complete list of changes, run:

  corelist --diff 5.20.0 5.22.0

You can substitute your favorite version in place of 5.20.0, too.

Some notable changes include:

the Archive::Tar manpage

Tests can now be run in parallel.

the attributes manpage

The usage of memEQs in the XS has been corrected. [perl #122701]

Avoid reading beyond the end of a buffer. [perl #122629]

the B manpage

It provides a new B::safename function, based on the existing B::GV->SAFENAME, that converts \cOPEN to ^OPEN.

Nulled COPs are now of class B::COP, rather than B::OP.

B::REGEXP objects now provide a qr_anoncv method for accessing the implicit CV associated with qr// things containing code blocks, and a compflags method that returns the pertinent flags originating from the qr//blahblah op.

B::PMOP now provides a pmregexp method returning a B::REGEXP object. Two new classes, B::PADNAME and B::PADNAMELIST, have been introduced.

A bug where, after an ithread creation or psuedofork, special/immortal SVs in the child ithread/psuedoprocess did not have the correct class of B::SPECIAL, has been fixed. The id and outid PADLIST methods have been added.

the B::Concise manpage

Null ops that are part of the execution chain are now given sequence numbers.

Private flags for nulled ops are now dumped with mnemonics as they would be for the non-nulled counterparts.

the B::Deparse manpage

It now deparses +sub : attr { ... } correctly at the start of a statement. Without the initial +, sub would be a statement label.

BEGIN blocks are now emitted in the right place most of the time, but the change unfortunately introduced a regression, in that BEGIN blocks occurring just before the end of the enclosing block may appear below it instead.

B::Deparse no longer puts erroneous local here and there, such as for LIST = tr/a//d. [perl #119815]

Adjacent use statements are no longer accidentally nested if one contains a do block. [perl #115066]

Parenthesised arrays in lists passed to \ are now correctly deparsed with parentheses (e.g., \(@a, (@b), @c) now retains the parentheses around @b), thus preserving the flattening behavior of referenced parenthesised arrays. Formerly, it only worked for one array: \(@a).

local our is now deparsed correctly, with the our included.

for($foo; !$bar; $baz) {...} was deparsed without the ! (or not). This has been fixed.

Core keywords that conflict with lexical subroutines are now deparsed with the CORE:: prefix.

foreach state $x (...) {...} now deparses correctly with state and not my.

our @array = split(...) now deparses correctly with our in those cases where the assignment is optimized away.

It now deparses our(LIST) and typed lexical (my Dog $spot) correctly.

Deparse $#_ as that instead of as $#{_}. [perl #123947]

BEGIN blocks at the end of the enclosing scope are now deparsed in the right place. [perl #77452]

BEGIN blocks were sometimes deparsed as __ANON__, but are now always called BEGIN.

Lexical subroutines are now fully deparsed. [perl #116553]

Anything =~ y///r with /r no longer omits the left-hand operand.

The op trees that make up regexp code blocks are now deparsed for real. Formerly, the original string that made up the regular expression was used. That caused problems with qr/(?{<<heredoc})/ and multiline code blocks, which were deparsed incorrectly. [perl #123217] [perl #115256]

$; at the end of a statement no longer loses its semicolon. [perl #123357]

Some cases of subroutine declarations stored in the stash in shorthand form were being omitted.

Non-ASCII characters are now consistently escaped in strings, instead of some of the time. (There are still outstanding problems with regular expressions and identifiers that have not been fixed.)

When prototype sub calls are deparsed with & (e.g., under the -P option), scalar is now added where appropriate, to force the scalar context implied by the prototype.

require(foo()), do(foo()), goto(foo()) and similar constructs with loop controls are now deparsed correctly. The outer parentheses are not optional.

Whitespace is no longer escaped in regular expressions, because it was getting erroneously escaped within (?x:...) sections.

sub foo { foo() } is now deparsed with those mandatory parentheses.

/@array/ is now deparsed as a regular expression, and not just @array.

/@{-}/, /@{+}/ and $#{1} are now deparsed with the braces, which are mandatory in these cases.

In deparsing feature bundles, B::Deparse was emitting no feature; first instead of no feature ':all';. This has been fixed.

chdir FH is now deparsed without quotation marks.

\my @a is now deparsed without parentheses. (Parenthese would flatten the array.)

system and exec followed by a block are now deparsed correctly. Formerly there was an erroneous do before the block.

use constant QR => qr/.../flags followed by "" =~ QR is no longer without the flags.

Deparsing BEGIN { undef &foo } with the -w switch enabled started to emit 'uninitialized' warnings in Perl 5.14. This has been fixed.

Deparsing calls to subs with a (;+) prototype resulted in an infinite loop. The (;$) (_) and (;_) prototypes were given the wrong precedence, causing foo($a<$b) to be deparsed without the parentheses.

Deparse now provides a defined state sub in inner subs.

the B::Op_private manpage

the B::Op_private manpage provides detailed information about the flags used in the op_private field of perl opcodes.

the bigint manpage

the bignum manpage

the bigrat manpage

Document in CAVEATS that using strings as numbers won't always invoke the big number overloading, and how to invoke it. [rt.perl.org #123064]

the Carp manpage

Carp::Heavy now ignores version mismatches with Carp if Carp is newer than 1.12, since Carp::Heavy's guts were merged into Carp at that point. [perl #121574]

Carp now handles non-ASCII platforms better.

Off-by-one error fix for Perl < 5.14.

the constant manpage

It now accepts fully-qualified constant names, allowing constants to be defined in packages other than the caller.

the CPAN manpage

Add support for Cwd::getdcwd() and introduce workaround for a misbehavior seen on Strawberry Perl 5.20.1.

Fix chdir() after building dependencies bug.

Introduce experimental support for plugins/hooks.

Integrate the App::Cpan sources.

Do not check recursion on optional dependencies.

Sanity check META.yml to contain a hash. [cpan #95271]

the CPAN::Meta::Requirements manpage

Works around limitations in version::vpp detecting v-string magic and adds support for forthcoming the ExtUtils::MakeMaker manpage bootstrap version.pm for Perls older than 5.10.0.

the Data::Dumper manpage

Fixes CVE-2014-4330 by adding a configuration variable/option to limit recursion when dumping deep data structures.

Changes to resolve Coverity issues. XS dumps incorrectly stored the name of code references stored in a GLOB. [perl #122070]

the DynaLoader manpage

Remove dl_nonlazy global if unused in Dynaloader. [perl #122926]

the Encode manpage

piconv now has better error handling when the encoding name is nonexistent, and a build breakage when upgrading the Encode manpage in perl-5.8.2 and earlier has been fixed.

Building in C++ mode on Windows now works.

the Errno manpage

Add -P to the preprocessor command-line on GCC 5. GCC added extra line directives, breaking parsing of error code definitions. [rt.perl.org #123784]

the experimental manpage

Hardcodes features for Perls older than 5.15.7.

the ExtUtils::CBuilder manpage

Fixes a regression on Android. [perl #122675]

the ExtUtils::Manifest manpage

Fixes a bug with maniread()'s handling of quoted filenames and improves manifind() to follow symlinks. [perl #122415]

the ExtUtils::ParseXS manpage

Only declare file unused if we actually define it. Improve generated RETVAL code generation to avoid repeated references to ST(0). [perl #123278] Broaden and document the /OBJ$/ to /REF$/ typemap optimization for the DESTROY method. [perl #123418]

the Fcntl manpage

Add support for the Linux pipe buffer size fcntl() commands.

the File::Find manpage

find() and finddepth() will now warn if passed inappropriate or misspelled options.

the File::Glob manpage

Avoid SvIV() expanding to call get_sv() three times in a few places. [perl #123606]

the HTTP::Tiny manpage

keep_alive is now fork-safe and thread-safe.

the IO manpage

The XS implementation has been fixed for the sake of older Perls.

the IO::Socket manpage

Document the limitations of the connected() method. [perl #123096]

the IO::Socket::IP manpage

A better fix for subclassing connect(). [cpan #95983] [cpan #97050]

Implements Timeout for connect(). [cpan #92075]

Support for IPv6 and SSL to Net::FTP, Net::NNTP, Net::POP3 and Net::SMTP. Improvements in Net::SMTP authentication.

the Locale::Codes manpage

Fixed a bug in the scripts used to extract data from spreadsheets that prevented the SHP currency code from being found. [cpan #94229]

New codes have been added.

the Math::BigInt manpage

Synchronize POD changes from the CPAN release. Math::BigFloat->blog(x) would sometimes return blog(2*x) when the accuracy was greater than 70 digits. The result of Math::BigFloat->bdiv() in list context now satisfies x = quotient * divisor + remainder.

Correct handling of subclasses. [cpan #96254] [cpan #96329]

the Module::Metadata manpage

Support installations on older perls with an the ExtUtils::MakeMaker manpage earlier than 6.63_03

the overload manpage

A redundant ref $sub check has been removed.

A warning from the gcc compiler is now avoided when building the XS.

Don't turn leading // into / on Cygwin. [perl #122635]

perl5db.pl

The debugger would cause an assertion failure. [perl #124127]

fork() in the debugger under tmux will now create a new window for the forked process. [perl #121333]

The debugger now saves the current working directory on startup and restores it when you restart your program with R or rerun. [perl #121509]

the PerlIO::scalar manpage

Reading from a position well past the end of the scalar now correctly returns end of file. [perl #123443]

Seeking to a negative position still fails, but no longer leaves the file position set to a negation location.

eof() on a PerlIO::scalar handle now properly returns true when the file position is past the 2GB mark on 32-bit systems.

Attempting to write at file positions impossible for the platform now fail early rather than wrapping at 4GB.

the Pod::Perldoc manpage

Filehandles opened for reading or writing now have :encoding(UTF-8) set. [cpan #98019]

the POSIX manpage

The C99 math functions and constants (for example acosh, isinf, isnan, round, trunc; M_E, M_SQRT2, M_PI) have been added.

POSIX::tmpnam() now produces a deprecation warning. [perl #122005]

the Safe manpage

reval was not propagating void context properly.

A new module, the Sub::Util manpage, has been added, containing functions related to CODE refs, including subname (inspired by Sub::Identity) and set_subname (copied and renamed from Sub::Name). The use of GetMagic in List::Util::reduce() has also been fixed. [cpan #63211]

the SDBM_File manpage

Simplified the build process. [perl #123413]

the Time::Piece manpage

When pretty printing negative Time::Seconds, the ``minus'' is no longer lost.

the Unicode::Collate manpage

Version 0.67's improved discontiguous contractions is invalidated by default and is supported as a parameter long_contraction.

the Unicode::Normalize manpage

The XSUB implementation has been removed in favor of pure Perl.

the Unicode::UCD manpage

A new function property_values() has been added to return a given property's possible values.

A new function charprop() has been added to return the value of a given property for a given code point.

A new function charprops_all() has been added to return the values of all Unicode properties for a given code point.

A bug has been fixed so that propaliases() returns the correct short and long names for the Perl extensions where it was incorrect.

A bug has been fixed so that prop_value_aliases() returns undef instead of a wrong result for properties that are Perl extensions.

This module now works on EBCDIC platforms.

the utf8 manpage

A mismatch between the documentation and the code in utf8::downgrade() was fixed in favor of the documentation. The optional second argument is now correctly treated as a perl boolean (true/false semantics) and not as an integer.

the version manpage

Numerous changes. See the Changes file in the CPAN distribution for details.

the Win32 manpage

GetOSName() now supports Windows 8.1, and building in C++ mode now works.

the Win32API::File manpage

Building in C++ mode now works.

the XSLoader manpage

Allow XSLoader to load modules from a different namespace. [perl #122455]

Removed Modules and Pragmata

The following modules (and associated modules) have been removed from the core perl distribution:

the CGI manpage

the Module::Build manpage

Documentation

New Documentation

the perlunicook manpage

This document, by Tom Christiansen, provides examples of handling Unicode in Perl.

Changes to Existing Documentation

the perlaix manpage

the perlapi manpage

SvSetSV

sv_usepvn_flags

Newx

malloc

[perl #121869]

NUL

the perldata manpage

the perlebcdic manpage

the perlfilter manpage

LIMITATIONS

the perlfunc manpage

study()

delete

exists

our

-l

[perl #121523]

exec LIST

system LIST

exec PROGRAM LIST

system PROGRAM LIST

This has also been noted in the perlport manpage.

[perl #122046]

the perlguts manpage

the perlhack manpage

the perlhacktips manpage

tmpfile

atoi

strtol

strtoul

test.valgrind

make

[perl #121431]

the perlhpux manpage

the perllocale manpage

the perlmodstyle manpage

PrePAN

the perlop manpage

the perlpodspec manpage

the perlpolicy manpage

p5p

STANDARDS OF CONDUCT in the perlpolicy manpage

the perlport manpage

the perlre manpage

/x

/n

the perlrebackslash manpage

\b{sb}

\b{wb}

\b{gcb}

\b{g}

the perlrecharclass manpage

Character Ranges in the perlrecharclass manpage

[A-Z]

[a-z]

[0-9]

qr/[\N{named sequence}]/

Selected Bug Fixes

the perlref manpage

Assigning to References

the perlsec manpage

the perlsyn manpage

...

[perl #122661]

for

while

the perlsyn manpage

the perlunicode manpage

Noncharacter code points in the perlunicode manpage

the perluniintro manpage

the perlvar manpage

$]

$^V

$OLD_PERL_VERSION

$]

${^ENCODING}

%^H

the perlvms manpage

the perlxs manpage

Diagnostics

The following additions or changes have been made to diagnostic output, including warnings and fatal error messages. For the complete list of diagnostic messages, see the perldiag manpage.

New Diagnostics

New Errors

Bad symbol for scalar

(P) An internal request asked to add a scalar entry to something that wasn't a symbol table entry.

Can't use a hash as a reference

(F) You tried to use a hash as a reference, as in %foo->{"bar"} or %$ref->{"hello"}. Versions of perl <= 5.6.1 used to allow this syntax, but shouldn't have.

Can't use an array as a reference

(F) You tried to use an array as a reference, as in @foo->[23] or @$ref->[99]. Versions of perl <= 5.6.1 used to allow this syntax, but shouldn't have.

Can't use 'defined(@array)' (Maybe you should just omit the defined()?)

(F) defined() is not useful on arrays because it checks for an undefined scalar value. If you want to see if the array is empty, just use if (@array) { # not empty } for example.

Can't use 'defined(%hash)' (Maybe you should just omit the defined()?)

(F) defined() is not usually right on hashes.

Although defined %hash is false on a plain not-yet-used hash, it becomes true in several non-obvious circumstances, including iterators, weak references, stash names, even remaining true after undef %hash. These things make defined %hash fairly useless in practice, so it now generates a fatal error.

If a check for non-empty is what you wanted then just put it in boolean context (see Scalar values in the perldata manpage):

    if (%hash) {
       # not empty
    }

If you had defined %Foo::Bar::QUUX to check whether such a package variable exists then that's never really been reliable, and isn't a good way to enquire about the features of a package, or whether it's loaded, etc.

Cannot chr %f

(F) You passed an invalid number (like an infinity or not-a-number) to chr.

Cannot compress %f in pack

(F) You tried converting an infinity or not-a-number to an unsigned character, which makes no sense.

Cannot pack %f with '%c'

(F) You tried converting an infinity or not-a-number to a character, which makes no sense.

Cannot print %f with '%c'

(F) You tried printing an infinity or not-a-number as a character (%c), which makes no sense. Maybe you meant '%s', or just stringifying it?

charnames alias definitions may not contain a sequence of multiple spaces

(F) You defined a character name which had multiple space characters in a row. Change them to single spaces. Usually these names are defined in the :alias import argument to use charnames, but they could be defined by a translator installed into $^H{charnames}. See CUSTOM ALIASES in the charnames manpage.

charnames alias definitions may not contain trailing white-space

(F) You defined a character name which ended in a space character. Remove the trailing space(s). Usually these names are defined in the :alias import argument to use charnames, but they could be defined by a translator installed into $^H{charnames}. See CUSTOM ALIASES in the charnames manpage.

:const is not permitted on named subroutines

(F) The const attribute causes an anonymous subroutine to be run and its value captured at the time that it is cloned. Named subroutines are not cloned like this, so the attribute does not make sense on them.

Hexadecimal float: internal error

(F) Something went horribly bad in hexadecimal float handling.

Hexadecimal float: unsupported long double format

(F) You have configured Perl to use long doubles but the internals of the long double format are unknown, therefore the hexadecimal float output is impossible.

Illegal suidscript

(F) The script run under suidperl was somehow illegal.

In '(?...)', the '(' and '?' must be adjacent in regex; marked by <-- HERE in m/%s/

(F) The two-character sequence "(?" in this context in a regular expression pattern should be an indivisible token, with nothing intervening between the "(" and the "?", but you separated them.

In '(*VERB...)', the '(' and '*' must be adjacent in regex; marked by <-- HERE in m/%s/

(F) The two-character sequence "(*" in this context in a regular expression pattern should be an indivisible token, with nothing intervening between the "(" and the "*", but you separated them.

Invalid quantifier in {,} in regex; marked by <-- HERE in m/%s/

(F) The pattern looks like a {min,max} quantifier, but the min or max could not be parsed as a valid number: either it has leading zeroes, or it represents too big a number to cope with. The <-- HERE shows where in the regular expression the problem was discovered. See the perlre manpage.

'%s' is an unknown bound type in regex

(F) You used \b{...} or \B{...} and the ... is not known to Perl. The current valid ones are given in \b{}, \b, \B{}, \B in the perlrebackslash manpage.

Missing or undefined argument to require

(F) You tried to call require with no argument or with an undefined value as an argument. require expects either a package name or a file-specification as an argument. See require in the perlfunc manpage.

Formerly, require with no argument or undef warned about a Null filename.

New Warnings

\C is deprecated in regex

(D deprecated) The /\C/ character class was deprecated in v5.20, and now emits a warning. It is intended that it will become an error in v5.24. This character class matches a single byte even if it appears within a multi-byte character, breaks encapsulation, and can corrupt UTF-8 strings.

``%s'' is more clearly written simply as ``%s'' in regex; marked by <-- HERE in m/%s/

(W regexp) (only under use re 'strict' or within (?[...]))

You specified a character that has the given plainer way of writing it, and which is also portable to platforms running with different character sets.

Argument ``%s'' treated as 0 in increment (++)

(W numeric) The indicated string was fed as an argument to the ++ operator which expects either a number or a string matching /^[a-zA-Z]*[0-9]*\z/. See Auto-increment and Auto-decrement in the perlop manpage for details.

Both or neither range ends should be Unicode in regex; marked by <-- HERE in m/%s/

(W regexp) (only under use re 'strict' or within (?[...]))

In a bracketed character class in a regular expression pattern, you had a range which has exactly one end of it specified using \N{}, and the other end is specified using a non-portable mechanism. Perl treats the range as a Unicode range, that is, all the characters in it are considered to be the Unicode characters, and which may be different code points on some platforms Perl runs on. For example, [\N{U+06}-\x08] is treated as if you had instead said [\N{U+06}-\N{U+08}], that is it matches the characters whose code points in Unicode are 6, 7, and 8. But that \x08 might indicate that you meant something different, so the warning gets raised.

Can't do %s(``%s'') on non-UTF-8 locale; resolved to ``%s''.

(W locale) You are 1) running under ``use locale''; 2) the current locale is not a UTF-8 one; 3) you tried to do the designated case-change operation on the specified Unicode character; and 4) the result of this operation would mix Unicode and locale rules, which likely conflict.

The warnings category locale is new.

:const is experimental

(S experimental::const_attr) The const attribute is experimental. If you want to use the feature, disable the warning with no warnings 'experimental::const_attr', but know that in doing so you are taking the risk that your code may break in a future Perl version.

gmtime(%f) failed

(W overflow) You called gmtime with a number that it could not handle: too large, too small, or NaN. The returned value is undef.

Hexadecimal float: exponent overflow

(W overflow) The hexadecimal floating point has larger exponent than the floating point supports.

Hexadecimal float: exponent underflow

(W overflow) The hexadecimal floating point has smaller exponent than the floating point supports.

Hexadecimal float: mantissa overflow

(W overflow) The hexadecimal floating point literal had more bits in the mantissa (the part between the 0x and the exponent, also known as the fraction or the significand) than the floating point supports.

Hexadecimal float: precision loss

(W overflow) The hexadecimal floating point had internally more digits than could be output. This can be caused by unsupported long double formats, or by 64-bit integers not being available (needed to retrieve the digits under some configurations).

Locale '%s' may not work well.%s

(W locale) You are using the named locale, which is a non-UTF-8 one, and which perl has determined is not fully compatible with what it can handle. The second %s gives a reason.

The warnings category locale is new.

localtime(%f) failed

(W overflow) You called localtime with a number that it could not handle: too large, too small, or NaN. The returned value is undef.

Negative repeat count does nothing

(W numeric) You tried to execute the x repetition operator fewer than 0 times, which doesn't make sense.

NO-BREAK SPACE in a charnames alias definition is deprecated

(D deprecated) You defined a character name which contained a no-break space character. Change it to a regular space. Usually these names are defined in the :alias import argument to use charnames, but they could be defined by a translator installed into $^H{charnames}. See CUSTOM ALIASES in the charnames manpage.

Non-finite repeat count does nothing

(W numeric) You tried to execute the x repetition operator Inf (or -Inf) or NaN times, which doesn't make sense.

PerlIO layer ':win32' is experimental

(S experimental::win32_perlio) The :win32 PerlIO layer is experimental. If you want to take the risk of using this layer, simply disable this warning:

    no warnings "experimental::win32_perlio";

Ranges of ASCII printables should be some subset of ``0-9'', ``A-Z'', or ``a-z'' in regex; marked by <-- HERE in m/%s/

(W regexp) (only under use re 'strict' or within (?[...]))

Stricter rules help to find typos and other errors. Perhaps you didn't even intend a range here, if the "-" was meant to be some other character, or should have been escaped (like "\-"). If you did intend a range, the one that was used is not portable between ASCII and EBCDIC platforms, and doesn't have an obvious meaning to a casual reader.

 [3-7]    # OK; Obvious and portable
 [d-g]    # OK; Obvious and portable
 [A-Y]    # OK; Obvious and portable
 [A-z]    # WRONG; Not portable; not clear what is meant
 [a-Z]    # WRONG; Not portable; not clear what is meant
 [%-.]    # WRONG; Not portable; not clear what is meant
 [\x41-Z] # WRONG; Not portable; not obvious to non-geek

(You can force portability by specifying a Unicode range, which means that the endpoints are specified by \N{...}, but the meaning may still not be obvious.) The stricter rules require that ranges that start or stop with an ASCII character that is not a control have all their endpoints be a literal character, and not some escape sequence (like "\x41"), and the ranges must be all digits, or all uppercase letters, or all lowercase letters.

Ranges of digits should be from the same group in regex; marked by <-- HERE in m/%s/

(W regexp) (only under use re 'strict' or within (?[...]))

Stricter rules help to find typos and other errors. You included a range, and at least one of the end points is a decimal digit. Under the stricter rules, when this happens, both end points should be digits in the same group of 10 consecutive digits.

Redundant argument in %s

(W redundant) You called a function with more arguments than were needed, as indicated by information within other arguments you supplied (e.g. a printf format). Currently only emitted when a printf-type format required fewer arguments than were supplied, but might be used in the future for e.g. pack in the perlfunc manpage.

The warnings category redundant is new. See also [perl #121025].

Replacement list is longer than search list

This is not a new diagnostic, but in earlier releases was accidentally not displayed if the transliteration contained wide characters. This is now fixed, so that you may see this diagnostic in places where you previously didn't (but should have).

Use of \b{} for non-UTF-8 locale is wrong. Assuming a UTF-8 locale

(W locale) You are matching a regular expression using locale rules, and a Unicode boundary is being matched, but the locale is not a Unicode one. This doesn't make sense. Perl will continue, assuming a Unicode (UTF-8) locale, but the results could well be wrong except if the locale happens to be ISO-8859-1 (Latin1) where this message is spurious and can be ignored.

The warnings category locale is new.

Using /u for '%s' instead of /%s in regex; marked by <-- HERE in m/%s/

(W regexp) You used a Unicode boundary (\b{...} or \B{...}) in a portion of a regular expression where the character set modifiers /a or /aa are in effect. These two modifiers indicate an ASCII interpretation, and this doesn't make sense for a Unicode definition. The generated regular expression will compile so that the boundary uses all of Unicode. No other portion of the regular expression is affected.

The bitwise feature is experimental

(S experimental::bitwise) This warning is emitted if you use bitwise operators (& | ^ ~ &. |. ^. ~.) with the ``bitwise'' feature enabled. Simply suppress the warning if you want to use the feature, but know that in doing so you are taking the risk of using an experimental feature which may change or be removed in a future Perl version:

    no warnings "experimental::bitwise";
    use feature "bitwise";
    $x |.= $y;

Unescaped left brace in regex is deprecated, passed through in regex; marked by <-- HERE in m/%s/

(D deprecated, regexp) You used a literal "{" character in a regular expression pattern. You should change to use "\{" instead, because a future version of Perl (tentatively v5.26) will consider this to be a syntax error. If the pattern delimiters are also braces, any matching right brace ("}") should also be escaped to avoid confusing the parser, for example,

    qr{abc\{def\}ghi}

Use of literal non-graphic characters in variable names is deprecated

(D deprecated) Using literal non-graphic (including control) characters in the source to refer to the ^FOO variables, like $^X and ${^GLOBAL_PHASE} is now deprecated.

Useless use of attribute ``const''

(W misc) The const attribute has no effect except on anonymous closure prototypes. You applied it to a subroutine via attributes.pm. This is only useful inside an attribute handler for an anonymous subroutine.

Useless use of /d modifier in transliteration operator

"use re 'strict'" is experimental

(S experimental::re_strict) The things that are different when a regular expression pattern is compiled under 'strict' are subject to change in future Perl releases in incompatible ways; there are also proposals to change how to enable strict checking instead of using this subpragma. This means that a pattern that compiles today may not in a future Perl release. This warning is to alert you to that risk.

Warning: unable to close filehandle properly: %s

Warning: unable to close filehandle %s properly: %s

(S io) Previously, perl silently ignored any errors when doing an implicit close of a filehandle, i.e. where the reference count of the filehandle reached zero and the user's code hadn't already called close(); e.g.

    {
        open my $fh, '>', $file  or die "open: '$file': $!\n";
        print $fh, $data  or die;
    } # implicit close here

In a situation such as disk full, due to buffering, the error may only be detected during the final close, so not checking the result of the close is dangerous.

So perl now warns in such situations.

Wide character (U+%X) in %s

(W locale) While in a single-byte locale (i.e., a non-UTF-8 one), a multi-byte character was encountered. Perl considers this character to be the specified Unicode code point. Combining non-UTF-8 locales and Unicode is dangerous. Almost certainly some characters will have two different representations. For example, in the ISO 8859-7 (Greek) locale, the code point 0xC3 represents a Capital Gamma. But so also does 0x393. This will make string comparisons unreliable.

You likely need to figure out how this multi-byte character got mixed up with your single-byte locale (or perhaps you thought you had a UTF-8 locale, but Perl disagrees).

The warnings category locale is new.

Changes to Existing Diagnostics

This warning has been changed to < at require-statement should be quotes> to make the issue more identifiable.

Argument ``%s'' isn't numeric%s

The the perldiag manpage entry for this warning has added this clarifying note:

 Note that for the Inf and NaN (infinity and not-a-number) the
 definition of "numeric" is somewhat unusual: the strings themselves
 (like "Inf") are considered numeric, and anything following them is
 considered non-numeric.

Global symbol ``%s'' requires explicit package name

This message has had '(did you forget to declare ``my %s''?)' appended to it, to make it more helpful to new Perl programmers. [perl #121638]

\N{} in character class restricted to one character in regex; marked by <-- HERE

This message has had character class changed to inverted character class or as a range end-point is to reflect improvements in qr/[\N{named sequence}]/ (see under Selected Bug Fixes).

panic: frexp

This message has had ': %f' appended to it, to show what the offending floating point number is.

Possible precedence problem on bitwise %c operator

Possible precedence problem on bitwise %s operator

Unsuccessful %s on filename containing newline

This warning is now only produced when the newline is at the end of the filename.

%s

Variable length lookbehind not implemented in regex m/%s/

The the perldiag manpage entry for this warning has had information about Unicode behavior added.

Diagnostic Removals

There is actually no ambiguity here, and this impedes the use of negated constants; e.g., -Inf.

Compile-time checking of constant dereferencing (e.g., my_constant->()) has been removed, since it was not taking overloading into account. [perl #69456] [perl #122607]

Utility Changes

find2perl, s2p and a2p removal

x2p/

This removes find2perl, s2p and a2p. They have all been released to CPAN as separate distributions (App::find2perl, App::s2p, App::a2p).

the h2ph manpage

h2ph

$Config{cppsymbols}

[perl #123784]

the encguess manpage

Configuration and Compilation

Configure

lrintl()

lroundl()

llrintl()

llroundl()

Configure

-Dmksymlinks

[perl #122002]

pthreads

cl

-Dusethreads

INSTALL

make test.valgrind

For example:

    TEST_JOBS=9 make test.valgrind

See valgrind in the perlhacktips manpage for more information.

[perl #121431]

This was an unmaintained attempt at preserving the Perl parse tree more faithfully so that automatic conversion of Perl 5 to Perl 6 would have been easier.

This build-time configuration option had been unmaintained for years, and had probably seriously diverged on both Perl 5 and Perl 6 sides.

-DPERL_OP_PARENT

Internal Changes

Testing

t/porting/re_context.t

the utf8 manpage

$1..$n

Perl_save_re_context()

t/perf/taint.t

t/re/speed.t

t/re/speed_thr.t

watchdog()

test.pl

plan skip_all => $reason

Test::More

op/infnan.t

Infinity and NaN (not-a-number) handling improved

Platform Support

Regained Platforms

IRIX and Tru64 platforms are working again.: Some make test failures remain: [perl #123977] and [perl #125298] for IRIX; [perl #124212], [cpan #99605], and [cpan #104836] for Tru64.
z/OS running EBCDIC Code Page 1047: Core perl now works on this EBCDIC platform. Earlier perls also worked, but, even though support wasn't officially withdrawn, recent perls would not compile and run well. Perl 5.20 would work, but had many bugs which have now been fixed. Many CPAN modules that ship with Perl still fail tests, including Pod::Simple. However the version of Pod::Simple currently on CPAN should work; it was fixed too late to include in Perl 5.22. Work is under way to fix many of the still-broken CPAN modules, which likely will be installed on CPAN when completed, so that you may not have to wait until Perl 5.24 to get a working version.

Discontinued Platforms

NeXTSTEP/OPENSTEP: NeXTSTEP was a proprietary operating system bundled with NeXT's workstations in the early to mid 90s; OPENSTEP was an API specification that provided a NeXTSTEP-like environment on a non-NeXTSTEP system. Both are now long dead, so support for building Perl on them has been removed.

Platform-Specific Notes

EBCDIC: Special handling is required of the perl interpreter on EBCDIC platforms to get qr/[i-j]/ to match only "i" and "j", since there are 7 characters between the code points for "i" and "j". This special handling had only been invoked when both ends of the range are literals. Now it is also invoked if any of the \N{...} forms for specifying a character by name or Unicode code point is used instead of a literal. See Character Ranges in the perlrecharclass manpage.
HP-UX: The archname now distinguishes use64bitint from use64bitall.
Android: Build support has been improved for cross-compiling in general and for Android in particular.
VMS
Win32
OpenBSD: On OpenBSD, Perl will now default to using the system malloc due to the security features it provides. Perl's own malloc wrapper has been in use since v5.14 due to performance reasons, but the OpenBSD project believes the tradeoff is worth it and would prefer that users who need the speed specifically ask for it.; [perl #122000].
Solaris

Internal Changes

-DPERL_OP_PARENT

op_sibling

On PERL_OP_PARENT builds, the op_sibling field has been renamed op_sibparent and a new flag, op_moresib, added. On the last op in a sibling chain, op_moresib is false and op_sibparent points to the parent (if any) rather than being NULL.

To make existing code work transparently whether using PERL_OP_PARENT or not, a number of new macros and functions have been added that should be used, rather than directly manipulating op_sibling.

For the case of just reading op_sibling to determine the next sibling, two new macros have been added. A simple scan through a sibling chain like this:

    for (; kid->op_sibling; kid = kid->op_sibling) { ... }

should now be written as:

    for (; OpHAS_SIBLING(kid); kid = OpSIBLING(kid)) { ... }

For altering optrees, a general-purpose function op_sibling_splice() has been added, which allows for manipulation of a chain of sibling ops. By analogy with the Perl function splice(), it allows you to cut out zero or more ops from a sibling chain and replace them with zero or more new ops. It transparently handles all the updating of sibling, parent, op_last pointers etc.

If you need to manipulate ops at a lower level, then three new macros, OpMORESIB_set, OpLASTSIB_set and OpMAYBESIB_set are intended to be a low-level portable way to set op_sibling / op_sibparent while also updating op_moresib. The first sets the sibling pointer to a new sibling, the second makes the op the last sibling, and the third conditionally does the first or second action. Note that unlike op_sibling_splice() these macros won't maintain consistency in the parent at the same time (e.g. by updating op_first and op_last where appropriate).

A C-level Perl_op_parent() function and a Perl-level B::OP::parent() method have been added. The C function only exists under PERL_OP_PARENT builds (using it is build-time error on vanilla perls). B::OP::parent() exists always, but on a vanilla build it always returns NULL. Under PERL_OP_PARENT, they return the parent of the current op, if any. The variable $B::OP::does_parent allows you to determine whether B supports retrieving an op's parent.

PERL_OP_PARENT was introduced in 5.21.2, but the interface was changed considerably in 5.21.11. If you updated your code before the 5.21.11 changes, it may require further revision. The main changes after 5.21.2 were:

OP_SIBLING

OP_HAS_SIBLING

OpSIBLING

OpHAS_SIBLING

op_lastsib

op_moresib

OpSIBLING_set

OpMORESIB_set

et al

op_sibling_splice()

parent

LC_NUMERIC

atoi

et al

grok_atou

grok_atoUV

the perlclib manpage

Perl_sv_get_backrefs()

screaminstr()

newDEFSVOP()

block_start()

block_end()

intro_my()

convert

op.c

op_convert_list

sv_magic()

[perl #123103]

CvPADLIST in the perlapi manpage

The CvPADLIST field has been reused for a different internal purpose for XSUBs. So in particular, you can no longer rely on it being NULL as a test of whether a CV is an XSUB. Use CvISXSUB() instead.

SVt_NV

sizeof(NV) <=
sizeof(IV)

$DB::single

$DB::signal

$DB::trace

pp_dbstate()

[perl #122445]

Perl_tmps_grow()

EXTEND_MORTAL

SVs_PADMY

SvPADMY()

PADTMP

SVs_PADMY

SETsv

SETsvUN

SvFAKE

sv_catpvn_flags()

SV_CATBYTES

SV_CATUTF8

METHOP

OP_METHOD and OP_METHOD_NAMED have changed from being UNOP/SVOP to being METHOP.

cv_name()

[perl #116735] [perl #120441]

cv_set_call_checker_flags()

cv_set_call_checker()

cv_name()

cv_set_call_checker()

[perl #116735]

CvGV

CvHASGV

CvGV

[perl #120441]

sync_locale in the perlapi manpage

Gtk

op_private

regen/op_private

Concise

perl -Dx

op_free()

op_private

PL_sv_objcount

LC_NUMERIC

POSIX::setlocale()

LC_NUMERIC

STORE_LC_NUMERIC_SET_TO_NEEDED

STORE_LC_NUMERIC_FORCE_TO_UNDERLYING

isUTF8_CHAR

Perl_cast_ulong

Perl_cast_i32

Perl_cast_iv

Perl_cast_uv

Perl_cv_const_sv

Perl_mg_find

Perl_mg_findext

Perl_mg_magical

Perl_mini_mktime

Perl_my_dirfd

Perl_sv_backoff

Perl_utf8_hop

Note that the prefix-less versions of those functions that are part of the public API, such as cast_i32(), remain unaffected.

PADNAME

PADNAMELIST

[perl #123223]

PadnameUTF8

UNOP_AUX

UNOP

op_aux

op_sv

OP_MULTIDEREF

$a[0]{$k}[$i]

rv2Xv

Xelem

gvsv

const

multideref

local

exists

delete

[$i+1]

aelem

helem

aelemfast

Selected Bug Fixes

close

$!

When an I/O error occurs, the fact that there has been an error is recorded in the handle. close returns false for such a handle. Previously, the value of $! would be untouched by close, so the common convention of writing close $fh or die $! did not work reliably. Now the handle records the value of $!, too, and close restores it.

no re

use re

Previously, running no re would turn off only a few things. Now it can turn off all the enabled things. For example, the only way to stop debugging, once enabled, was to exit the enclosing block; that is now fixed.

pack("D", $x)

pack("F", $x)

op/pack.t

[perl #123971]

[perl #124127]

*x=<y>

[perl #123790]

[perl #124099]

[perl #124113]

[perl #123202]

[perl #123801]

[perl #123802]

[perl #123955]

[perl #123995]

split

$_

[perl #123763]

my $x : attr

[perl #123817]

@

[perl #123963]

*bar::=*foo::=*glob_with_hash

[perl #123847]

foreach

print 4, scalar do { foreach(@x){} } + 1 would print 5.) It has been fixed to return undef. [perl #124004]

Several cases of data used to store environment variable contents in core C code being potentially overwritten before being used have been fixed. [perl #123748]

Some patterns starting with /.*..../ matched against long strings have been slow since v5.8, and some of the form /.*..../i have been slow since v5.18. They are now all fast again. [perl #123743].

The original visible value of $/ is now preserved when it is set to an invalid value. Previously if you set $/ to a reference to an array, for example, perl would produce a runtime error and not set PL_rs, but Perl code that checked $/ would see the array reference. [perl #123218].

In a regular expression pattern, a POSIX class, like [:ascii:], must be inside a bracketed character class, like qr/[[:ascii:]]/. A warning is issued when something looking like a POSIX class is not inside a bracketed class. That warning wasn't getting generated when the POSIX class was negated: [:^ascii:]. This is now fixed.

Perl 5.14.0 introduced a bug whereby eval { LABEL: } would crash. This has been fixed. [perl #123652].

Various crashes due to the parser getting confused by syntax errors have been fixed. [perl #123617]. [perl #123737]. [perl #123753]. [perl #123677].

Code like /$a[/ used to read the next line of input and treat it as though it came immediately after the opening bracket. Some invalid code consequently would parse and run, but some code caused crashes, so this is now disallowed. [perl #123712].

Fix argument underflow for pack. [perl #123874].

Fix handling of non-strict \x{}. Now \x{} is equivalent to \x{0} instead of faulting.

stat -t is now no longer treated as stackable, just like -t stat. [perl #123816].

The following no longer causes a SEGV: qr{x+(y(?0))*}.

Fixed infinite loop in parsing backrefs in regexp patterns.

Several minor bug fixes in behavior of Infinity and NaN, including warnings when stringifying Infinity-like or NaN-like strings. For example, ``NaNcy'' doesn't numify to NaN anymore.

A bug in regular expression patterns that could lead to segfaults and other crashes has been fixed. This occurred only in patterns compiled with /i while taking into account the current POSIX locale (which usually means they have to be compiled within the scope of use locale), and there must be a string of at least 128 consecutive bytes to match. [perl #123539].

s///g now works on very long strings (where there are more than 2 billion iterations) instead of dying with 'Substitution loop'. [perl #103260]. [perl #123071].

gmtime no longer crashes with not-a-number values. [perl #123495].

\() (a reference to an empty list), and y/// with lexical $_ in scope, could both do a bad write past the end of the stack. They have both been fixed to extend the stack first.

prototype() with no arguments used to read the previous item on the stack, so print "foo", prototype() would print foo's prototype. It has been fixed to infer $_ instead. [perl #123514].

Some cases of lexical state subs declared inside predeclared subs could crash, for example when evalling a string including the name of an outer variable, but no longer do.

Some cases of nested lexical state subs inside anonymous subs could cause 'Bizarre copy' errors or possibly even crashes.

When trying to emit warnings, perl's default debugger (perl5db.pl) was sometimes giving 'Undefined subroutine &DB::db_warn called' instead. This bug, which started to occur in Perl 5.18, has been fixed. [perl #123553].

Certain syntax errors in substitutions, such as s/${<>{})//, would crash, and had done so since Perl 5.10. (In some cases the crash did not start happening till 5.16.) The crash has, of course, been fixed. [perl #123542].

Fix a couple of string grow size calculation overflows; in particular, a repeat expression like 33 x ~3 could cause a large buffer overflow since the new output buffer size was not correctly handled by SvGROW(). An expression like this now properly produces a memory wrap panic. [perl #123554].

formline("@...", "a"); would crash. The FF_CHECKNL case in pp_formline() didn't set the pointer used to mark the chop position, which led to the FF_MORE case crashing with a segmentation fault. This has been fixed. [perl #123538].

A possible buffer overrun and crash when parsing a literal pattern during regular expression compilation has been fixed. [perl #123604].

fchmod() and futimes() now set $! when they fail due to being passed a closed file handle. [perl #122703].

op_free() and scalarvoid() no longer crash due to a stack overflow when freeing a deeply recursive op tree. [perl #108276].

In Perl 5.20.0, $^N accidentally had the internal UTF-8 flag turned off if accessed from a code block within a regular expression, effectively UTF-8-encoding the value. This has been fixed. [perl #123135].

A failed semctl call no longer overwrites existing items on the stack, which means that (semctl(-1,0,0,0))[0] no longer gives an ``uninitialized'' warning.

else{foo()} with no space before foo is now better at assigning the right line number to that statement. [perl #122695].

Sometimes the assignment in @array = split gets optimised so that split itself writes directly to the array. This caused a bug, preventing this assignment from being used in lvalue context. So (@a=split//,"foo")=bar() was an error. (This bug probably goes back to Perl 3, when the optimisation was added.) It has now been fixed. [perl #123057].

When an argument list fails the checks specified by a subroutine signature (which is still an experimental feature), the resulting error messages now give the file and line number of the caller, not of the called subroutine. [perl #121374].

The flip-flop operators (.. and ... in scalar context) used to maintain a separate state for each recursion level (the number of times the enclosing sub was called recursively), contrary to the documentation. Now each closure has one internal state for each flip-flop. [perl #122829].

The flip-flop operator (.. in scalar context) would return the same scalar each time, unless the containing subroutine was called recursively. Now it always returns a new scalar. [perl #122829].

use, no, statement labels, special blocks (BEGIN) and pod are now permitted as the first thing in a map or grep block, the block after print or say (or other functions) returning a handle, and within ${...}, @{...}, etc. [perl #122782].

The repetition operator x now propagates lvalue context to its left-hand argument when used in contexts like foreach. That allows for(($#that_array)x2) { ... } to work as expected if the loop modifies $_.

(...) x ... in scalar context used to corrupt the stack if one operand was an object with ``x'' overloading, causing erratic behavior. [perl #121827].

Assignment to a lexical scalar is often optimised away; for example in my $x; $x = $y + $z, the assign operator is optimised away and the add operator writes its result directly to $x. Various bugs related to this optimisation have been fixed. Certain operators on the right-hand side would sometimes fail to assign the value at all or assign the wrong value, or would call STORE twice or not at all on tied variables. The operators affected were $foo++, $foo--, and -$foo under

use
integer

, chomp, chr and setpgrp.

List assignments were sometimes buggy if the same scalar ended up on both sides of the assignment due to use of tied, values or each. The result would be the wrong value getting assigned.

setpgrp($nonzero) (with one argument) was accidentally changed in 5.16 to mean setpgrp(0). This has been fixed.

__SUB__ could return the wrong value or even corrupt memory under the debugger (the -d switch) and in subs containing eval $string.

When sub () { $var } becomes inlinable, it now returns a different scalar each time, just as a non-inlinable sub would, though Perl still optimises the copy away in cases where it would make no observable difference.

my sub f () { $var } and sub () : attr { $var } are no longer eligible for inlining. The former would crash; the latter would just throw the attributes away. An exception is made for the little-known :method attribute, which does nothing much.

Inlining of subs with an empty prototype is now more consistent than before. Previously, a sub with multiple statements, of which all but the last were optimised away, would be inlinable only if it were an anonymous sub containing a string eval or state declaration or closing over an outer lexical variable (or any anonymous sub under the debugger). Now any sub that gets folded to a single constant after statements have been optimised away is eligible for inlining. This applies to things like

sub
() { jabber() if DEBUG; 42 }

Some subroutines with an explicit return were being made inlinable, contrary to the documentation, Now return always prevents inlining.

On some systems, such as VMS, crypt can return a non-ASCII string. If a scalar assigned to had contained a UTF-8 string previously, then crypt would not turn off the UTF-8 flag, thus corrupting the return value. This would happen with $lexical = crypt ....

crypt no longer calls FETCH twice on a tied first argument.

An unterminated here-doc on the last line of a quote-like operator (qq[${ <<END }], /(?{ <<END })/) no longer causes a double free. It started doing so in 5.18.

index() and rindex() no longer crash when used on strings over 2GB in size. [perl #121562].

A small, previously intentional, memory leak in PERL_SYS_INIT/PERL_SYS_INIT3 on Win32 builds was fixed. This might affect embedders who repeatedly create and destroy perl engines within the same process.

POSIX::localeconv() now returns the data for the program's underlying locale even when called from outside the scope of use locale.

POSIX::localeconv() now works properly on platforms which don't have LC_NUMERIC and/or LC_MONETARY, or for which Perl has been compiled to disregard either or both of these locale categories. In such circumstances, there are now no entries for the corresponding values in the hash returned by localeconv().

POSIX::localeconv() now marks appropriately the values it returns as UTF-8 or not. Previously they were always returned as bytes, even if they were supposed to be encoded as UTF-8.

On Microsoft Windows, within the scope of use locale, the following POSIX character classes gave results for many locales that did not conform to the POSIX standard: [[:alnum:]], [[:alpha:]], [[:blank:]], [[:digit:]], [[:graph:]], [[:lower:]], [[:print:]], [[:punct:]], [[:upper:]], [[:word:]], and [[:xdigit:]]. This was because the underlying Microsoft implementation does not follow the standard. Perl now takes special precautions to correct for this.

Many issues have been detected by Coverity and fixed.

system() and friends should now work properly on more Android builds.

Due to an oversight, the value specified through -Dtargetsh to Configure would end up being ignored by some of the build process. This caused perls cross-compiled for Android to end up with defective versions of system(), exec() and backticks: the commands would end up looking for /bin/sh instead of /system/bin/sh, and so would fail for the vast majority of devices, leaving $! as ENOENT.

qr(...$...$...), qr[...\[...\]...], and qr{...\{...\}...} now work. Previously it was impossible to escape these three left-characters with a backslash within a regular expression pattern where otherwise they would be considered metacharacters, and the pattern opening delimiter was the character, and the closing delimiter was its mirror character.

s///e on tainted UTF-8 strings corrupted pos(). This bug, introduced in 5.20, is now fixed. [perl #122148].

A non-word boundary in a regular expression (\B) did not always match the end of the string; in particular q{} =~ /\B/ did not match. This bug, introduced in perl 5.14, is now fixed. [perl #122090].

" P" =~ /(?=.*P)P/ should match, but did not. This is now fixed. [perl #122171].

Failing to compile use Foo in an eval could leave a spurious BEGIN subroutine definition, which would produce a ``Subroutine BEGIN redefined'' warning on the next use of use, or other BEGIN block. [perl #122107].

method { BLOCK } ARGS syntax now correctly parses the arguments if they begin with an opening brace. [perl #46947].

External libraries and Perl may have different ideas of what the locale is. This is problematic when parsing version strings if the locale's numeric separator has been changed. Version parsing has been patched to ensure it handles the locales correctly. [perl #121930].

A bug has been fixed where zero-length assertions and code blocks inside of a regex could cause pos to see an incorrect value. [perl #122460].

Dereferencing of constants now works correctly for typeglob constants. Previously the glob was stringified and its name looked up. Now the glob itself is used. [perl #69456]

When parsing a sigil ($ @ % &) followed by braces, the parser no longer tries to guess whether it is a block or a hash constructor (causing a syntax error when it guesses the latter), since it can only be a block.

undef $reference now frees the referent immediately, instead of hanging on to it until the next statement. [perl #122556]

Various cases where the name of a sub is used (autoload, overloading, error messages) used to crash for lexical subs, but have been fixed.

Bareword lookup now tries to avoid vivifying packages if it turns out the bareword is not going to be a subroutine name.

Compilation of anonymous constants (e.g., sub () { 3 }) no longer deletes any subroutine named __ANON__ in the current package. Not only was *__ANON__{CODE} cleared, but there was a memory leak, too. This bug goes back to Perl 5.8.0.

Stub declarations like sub f; and sub f (); no longer wipe out constants of the same name declared by use constant. This bug was introduced in Perl 5.10.0.

qr/[\N{named sequence}]/ now works properly in many instances.

Some names known to \N{...} refer to a sequence of multiple characters, instead of the usual single character. Bracketed character classes generally only match single characters, but now special handling has been added so that they can match named sequences, but not if the class is inverted or the sequence is specified as the beginning or end of a range. In these cases, the only behavior change from before is a slight rewording of the fatal error message given when this class is part of a ?[...]) construct. When the [...] stands alone, the same non-fatal warning as before is raised, and only the first character in the sequence is used, again just as before.

Tainted constants evaluated at compile time no longer cause unrelated statements to become tainted. [perl #122669]

open $$fh, ..., which vivifies a handle with a name like "main::_GEN_0", was not giving the handle the right reference count, so a double free could happen.

When deciding that a bareword was a method name, the parser would get confused if an our sub with the same name existed, and look up the method in the package of the our sub, instead of the package of the invocant.

The parser no longer gets confused by \U= within a double-quoted string. It used to produce a syntax error, but now compiles it correctly. [perl #80368]

It has always been the intention for the -B and -T file test operators to treat UTF-8 encoded files as text. (perlfunc has been updated to say this.) Previously, it was possible for some files to be considered UTF-8 that actually weren't valid UTF-8. This is now fixed. The operators now work on EBCDIC platforms as well.

Under some conditions warning messages raised during regular expression pattern compilation were being output more than once. This has now been fixed.

Perl 5.20.0 introduced a regression in which a UTF-8 encoded regular expression pattern that contains a single ASCII lowercase letter did not match its uppercase counterpart. That has been fixed in both 5.20.1 and 5.22.0. [perl #122655]

Constant folding could incorrectly suppress warnings if lexical warnings (use warnings or no warnings) were not in effect and $^W were false at compile time and true at run time.

Loading Unicode tables during a regular expression match could cause assertion failures under debugging builds if the previous match used the very same regular expression. [perl #122747]

Thread cloning used to work incorrectly for lexical subs, possibly causing crashes or double frees on exit.

Since Perl 5.14.0, deleting $SomePackage::{__ANON__} and then undefining an anonymous subroutine could corrupt things internally, resulting in the Devel::Peek manpage crashing or B.pm giving nonsensical data. This has been fixed.

(caller $n)[3] now reports names of lexical subs, instead of treating them as "(unknown)".

sort subname LIST now supports using a lexical sub as the comparison routine.

Aliasing (e.g., via *x = *y) could confuse list assignments that mention the two names for the same variable on either side, causing wrong values to be assigned. [perl #15667]

Long here-doc terminators could cause a bad read on short lines of input. This has been fixed. It is doubtful that any crash could have occurred. This bug goes back to when here-docs were introduced in Perl 3.000 twenty-five years ago.

An optimization in split to treat split /^/ like split /^/m had the unfortunate side-effect of also treating split /\A/ like split /^/m, which it should not. This has been fixed. (Note, however, that split /^x/ does not behave like split /^x/m, which is also considered to be a bug and will be fixed in a future version.) [perl #122761]

The little-known my Class $var syntax (see the fields manpage and the attributes manpage) could get confused in the scope of use utf8 if Class were a constant whose value contained Latin-1 characters.

Locking and unlocking values via the Hash::Util manpage or Internals::SvREADONLY no longer has any effect on values that were read-only to begin with. Previously, unlocking such values could result in crashes, hangs or other erratic behavior.

Some unterminated (?(...)...) constructs in regular expressions would either crash or give erroneous error messages. /(?(1)/ is one such example.

pack "w", $tied no longer calls FETCH twice.

List assignments like ($x, $z) = (1, $y) now work correctly if $x and $y have been aliased by foreach.

Some patterns including code blocks with syntax errors, such as / (?{(^{})/, would hang or fail assertions on debugging builds. Now they produce errors.

An assertion failure when parsing sort with debugging enabled has been fixed. [perl #122771].

*a = *b; @a = split //, $b[1] could do a bad read and produce junk results.

In () = @array = split, the () = at the beginning no longer confuses the optimizer into assuming a limit of 1.

Fatal warnings no longer prevent the output of syntax errors. [perl #122966].

Fixed a NaN double-to-long-double conversion error on VMS. For quiet NaNs (and only on Itanium, not Alpha) negative infinity instead of NaN was produced.

Fixed the issue that caused make distclean to incorrectly leave some files behind. [perl #122820].

AIX now sets the length in getsockopt correctly. [perl #120835]. [cpan #91183]. [cpan #85570].

The optimization phase of a regexp compilation could run ``forever'' and exhaust all memory under certain circumstances; now fixed. [perl #122283].

The test script t/op/crypt.t > now uses the SHA-256 algorithm if the default one is disabled, rather than giving failures. [perl #121591].

Fixed an off-by-one error when setting the size of a shared array. [perl #122950].

Fixed a bug that could cause perl to enter an infinite loop during compilation. In particular, a while(1) within a sublist, e.g.

    sub foo { () = ($a, my $b, ($c, do { while(1) {} })) }

The bug was introduced in 5.20.0 [perl #122995].

On Win32, if a variable was local-ized in a pseudo-process that later forked, restoring the original value in the child pseudo-process caused memory corruption and a crash in the child pseudo-process (and therefore the OS process). [perl #40565].

Calling write on a format with a ^** field could produce a panic in sv_chop() if there were insufficient arguments or if the variable used to fill the field was empty. [perl #123245].

Non-ASCII lexical sub names now appear without trailing junk when they appear in error messages.

The \@ subroutine prototype no longer flattens parenthesized arrays (taking a reference to each element), but takes a reference to the array itself. [perl #47363].

A block containing nothing except a C-style for loop could corrupt the stack, causing lists outside the block to lose elements or have elements overwritten. This could happen with map { for(...){...} } ... and with lists containing do { for(...){...} }. [perl #123286].

scalar() now propagates lvalue context, so that for(scalar($#foo)) { ... } can modify $#foo through $_.

qr/@array(?{block})/ no longer dies with ``Bizarre copy of ARRAY''. [perl #123344].

eval '$variable' in nested named subroutines would sometimes look up a global variable even with a lexical variable in scope.

In perl 5.20.0, sort CORE::fake where 'fake' is anything other than a keyword, started chopping off the last 6 characters and treating the result as a sort sub name. The previous behavior of treating CORE::fake as a sort sub name has been restored. [perl #123410].

Outside of use utf8, a single-character Latin-1 lexical variable is disallowed. The error message for it, ``Can't use global $foo...'', was giving garbage instead of the variable name.

readline on a nonexistent handle was causing ${^LAST_FH} to produce a reference to an undefined scalar (or fail an assertion). Now ${^LAST_FH} ends up undefined.

(...) x ... in void context now applies scalar context to the left-hand argument, instead of the context the current sub was called in. [perl #123020].

Known Problems

pack

t/op/infnan.t

[perl 125203]

cmp

sort

\N{...}

tr///

y///

Version 8 Regular Expressions in the perlre manpage

pack

unpack

"U0"

the B::Generate manpage

the B::Utils manpage

Coro

Dancer

the Data::Alias manpage

the Data::Dump::Streamer manpage

the Data::Util manpage

the Devel::Spy manpage

invoker

the Lexical::Var manpage

the LWP::ConsoleLogger manpage

Mason

NgxQueue

Padre

the Parse::Keyword manpage

Obituary

Brian McCauley died on May 8, 2015. He was a frequent poster to Usenet, Perl Monks, and other Perl forums, and made several CPAN contributions under the nick NOBULL, including to the Perl FAQ. He attended almost every YAPC::Europe, and indeed, helped organise YAPC::Europe 2006 and the QA Hackathon 2009. His wit and his delight in intricate systems were particularly apparent in his love of board games; many Perl mongers will have fond memories of playing Fluxx and other games with Brian. He will be missed.

Acknowledgements

Perl 5.22.0 represents approximately 12 months of development since Perl 5.20.0 and contains approximately 590,000 lines of changes across 2,400 files from 94 authors.

Excluding auto-generated files, documentation and release tools, there were approximately 370,000 lines of changes to 1,500 .pm, .t, .c and .h files.

Perl continues to flourish into its third decade thanks to a vibrant community of users and developers. The following people are known to have contributed the improvements that became Perl 5.22.0:

Aaron Crane, Abhijit Menon-Sen, Abigail, Alberto Simões, Alex Solovey, Alex Vandiver, Alexandr Ciornii, Alexandre (Midnite) Jousset, Andreas König, Andreas Voegele, Andrew Fresh, Andy Dougherty, Anthony Heading, Aristotle Pagaltzis, brian d foy, Brian Fraser, Chad Granum, Chris 'BinGOs' Williams, Craig A. Berry, Dagfinn Ilmari Mannsåker, Daniel Dragan, Darin McBride, Dave Rolsky, David Golden, David Mitchell, David Wheeler, Dmitri Tikhonov, Doug Bell, E. Choroba, Ed J, Eric Herman, Father Chrysostomos, George Greer, Glenn D. Golden, Graham Knop, H.Merijn Brand, Herbert Breunung, Hugo van der Sanden, James E Keenan, James McCoy, James Raspass, Jan Dubois, Jarkko Hietaniemi, Jasmine Ngan, Jerry D. Hedden, Jim Cromie, John Goodyear, kafka, Karen Etheridge, Karl Williamson, Kent Fredric, kmx, Lajos Veres, Leon Timmermans, Lukas Mai, Mathieu Arnold, Matthew Horsfall, Max Maischein, Michael Bunk, Nicholas Clark, Niels Thykier, Niko Tyni, Norman Koch, Olivier Mengué, Peter John Acklam, Peter Martini, Petr Písař, Philippe Bruhat (BooK), Pierre Bogossian, Rafael Garcia-Suarez, Randy Stauner, Reini Urban, Ricardo Signes, Rob Hoelz, Rostislav Skudnov, Sawyer X, Shirakata Kentaro, Shlomi Fish, Sisyphus, Slaven Rezic, Smylers, Steffen Müller, Steve Hay, Sullivan Beck, syber, Tadeusz Sośnierz, Thomas Sibley, Todd Rinaldo, Tony Cook, Vincent Pit, Vladimir Marek, Yaroslav Kuzmin, Yves Orton, Ævar Arnfjörð Bjarmason.

The list above is almost certainly incomplete as it is automatically generated from version control history. In particular, it does not include the names of the (very much appreciated) contributors who reported issues to the Perl bug tracker.

Many of the changes included in this version originated in the CPAN modules included in Perl's core. We're grateful to the entire CPAN community for helping Perl to flourish.

For a more complete list of all of Perl's historical contributors, please see the AUTHORS file in the Perl source distribution.

Reporting Bugs

If you find what you think is a bug, you might check the articles recently posted to the comp.lang.perl.misc newsgroup and the perl bug database at https://rt.perl.org/. There may also be information at http://www.perl.org/, the Perl Home Page.

If you believe you have an unreported bug, please run the perlbug program included with your release. Be sure to trim your bug down to a tiny but sufficient test case. Your bug report, along with the output of perl -V, will be sent off to perlbug@perl.org to be analysed by the Perl porting team.

If the bug you are reporting has security implications, which make it inappropriate to send to a publicly archived mailing list, then please send it to perl5-security-report@perl.org. This points to a closed subscription unarchived mailing list, which includes all the core committers, who will be able to help assess the impact of issues, figure out a resolution, and help co-ordinate the release of patches to mitigate or fix the problem across all platforms on which Perl is supported. Please only use this address for security issues in the Perl core, not for modules independently distributed on CPAN.

prototype with no arguments

fileno now works on directory handles

The the Safe manpage module could allow outside packages to be replaced

qr/foo/x now ignores all Unicode pattern white space

defined(@array) and defined(%hash) are now fatal errors

`prototype` with no arguments

`fileno` now works on directory handles

`qr/foo/x` now ignores all Unicode pattern white space

`defined(@array)` and `defined(%hash)` are now fatal errors