PERL5140DELTA(1) Perl Programmers Reference Guide PERL5140DELTA(1)
NAME
perl5140delta - what is new for perl v5.14.0
DESCRIPTION
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
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.
Notice
As described in perlpolicy, the release of Perl 5.14.0 marks the
official end of support for Perl 5.10. Users of Perl 5.10 or earlier
should consider upgrading to a more recent release of Perl.
Core Enhancements
Unicode
Unicode Version 6.0 is now supported (mostly)
Perl comes with the Unicode 6.0 data base updated with Corrigendum #8
<http://www.unicode.org/versions/corrigendum8.html>;, with one exception
noted below. See <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.
Unicode 6.0 has chosen to use the name "BELL" for the character at
U+1F514, 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 "BELL" mean the ASCII "BEL" character, U+0007. In Perl 5.14,
"\N{BELL}" continues to mean U+0007, but its use generates a
deprecation warning message unless such warnings are turned off. The
new name for U+0007 in Perl is "ALERT", which corresponds nicely with
the existing shorthand sequence for it, "\a". "\N{BEL}" means U+0007,
with no warning given. The character at U+1F514 has no name in 5.14,
but can be referred to by "\N{U+1F514}". In Perl 5.16, "\N{BELL}" will
refer to U+1F514; all code that uses "\N{BELL}" should be converted to
use "\N{ALERT}", "\N{BEL}", or "\a" before upgrading.
Full functionality for "use feature 'unicode_strings'"
This release provides full functionality for "use feature
'unicode_strings'". Under its scope, all string operations executed
and regular expressions compiled (even if executed outside its scope)
have Unicode semantics. See "the 'unicode_strings' feature" in
feature. However, see "Inverted bracketed character classes and multi-
character folds", below.
This feature avoids most forms of the "Unicode Bug" (see "The "Unicode
Bug"" in perlunicode for details). If there is any possibility that
your code will process Unicode strings, you are strongly encouraged to
use this subpragma to avoid nasty surprises.
"\N{NAME}" and "charnames" enhancements
o "\N{NAME}" and "charnames::vianame" now know about the abbreviated
character names listed by Unicode, such as NBSP, SHY, LRO, ZWJ,
etc.; all 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.
o Unicode has several named character sequences, in which particular
sequences of code points are given names. "\N{NAME}" now
recognizes these.
o "\N{NAME}", "charnames::vianame", and "charnames::viacode" now know
about every character in Unicode. In earlier releases of Perl,
they didn't know about the Hangul syllables nor several CJK
(Chinese/Japanese/Korean) characters.
o It is now possible to override Perl's abbreviations with your own
custom aliases.
o You can now create a custom alias of the ordinal of a character,
known by "\N{NAME}", "charnames::vianame()", and
"charnames::viacode()". Previously, aliases had to be to official
Unicode character names. This made it impossible to create an
alias for unnamed code points, such as those reserved for private
use.
o The new function charnames::string_vianame() is a run-time version
of "\N{NAME}}", returning the string of characters whose Unicode
name is its parameter. It can handle Unicode named character
sequences, whereas the pre-existing charnames::vianame() cannot, as
the latter returns a single code point.
See charnames for details on all these changes.
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 other
warnings to remain on. The three categories are: "surrogate" when
UTF-16 surrogates are encountered; "nonchar" when Unicode non-character
code points are encountered; and "non_unicode" when code points above
the legal Unicode maximum of 0x10FFFF are encountered.
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 or the corresponding sub-category (see previous item) of
lexical warnings have been explicitly turned off, outputting or
executing a Unicode-defined operation such as upper-casing on such a
code point generates a warning. Attempting to input these using strict
rules (such as with the ":encoding(UTF-8)" layer) will continue to
fail. Prior to this release, handling was inconsistent and in places,
incorrect.
Unicode non-characters, some of which previously were erroneously
considered illegal in places by Perl, contrary to the Unicode Standard,
are now always legal internally. Inputting or outputting them works
the same as with the non-legal Unicode code points, because the Unicode
Standard says they are (only) illegal for "open interchange".
Unicode database files not installed
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 need these files, you can download them from
<http://www.unicode.org/Public/zipped/6.0.0/>;.
Regular Expressions
"(?^...)" construct signifies default modifiers
An ASCII caret "^" immediately following a "(?" in a regular expression
now means that the subexpression does not inherit surrounding modifiers
such as "/i", but reverts to the Perl defaults. Any modifiers
following the caret override the defaults.
Stringification of regular expressions now uses this notation. For
example, "qr/hlagh/i" would previously be stringified as
"(?i-xsm:hlagh)", but now it's stringified as "(?^i:hlagh)".
The main purpose of this change is to allow tests that rely on the
stringification not to have to change whenever new modifiers are added.
See "Extended Patterns" in perlre.
This change is likely to break code that compares stringified regular
expressions with fixed strings containing "?-xism".
"/d", "/l", "/u", and "/a" modifiers
Four new regular expression modifiers have been added. These are
mutually exclusive: one only can be turned on at a time.
o The "/l" modifier says to compile the regular expression as if it
were in the scope of "use locale", even if it is not.
o The "/u" modifier says to compile the regular expression as if it
were in the scope of a "use feature 'unicode_strings'" pragma.
o The "/d" (default) modifier is used to override any "use locale"
and "use feature 'unicode_strings'" pragmas in effect at the time
of compiling the regular expression.
o The "/a" regular expression modifier restricts "\s", "\d" and "\w"
and the POSIX ("[[:posix:]]") character classes to the ASCII range.
Their complements and "\b" and "\B" are correspondingly affected.
Otherwise, "/a" behaves like the "/u" modifier, in that case-
insensitive matching uses Unicode semantics.
If the "/a" modifier is repeated, then additionally in case-
insensitive matching, no ASCII character can match a non-ASCII
character. For example,
"k" =~ /\N{KELVIN SIGN}/ai
"\xDF" =~ /ss/ai
match but
"k" =~ /\N{KELVIN SIGN}/aai
"\xDF" =~ /ss/aai
do not match.
See "Modifiers" in perlre for more detail.
Non-destructive substitution
The substitution ("s///") and transliteration ("y///") operators now
support an "/r" option that copies the input variable, carries out the
substitution on the copy, and returns the result. The original remains
unmodified.
my $old = "cat";
my $new = $old =~ s/cat/dog/r;
# $old is "cat" and $new is "dog"
This is particularly useful with "map". See perlop for more examples.
Re-entrant regular expression engine
It is now safe to use regular expressions within "(?{...})" and
"(??{...})" code blocks inside regular expressions.
These blocks are still experimental, however, and still have problems
with lexical ("my") variables and abnormal exiting.
"use re '/flags'"
The "re" pragma now has the ability to turn on regular expression flags
till the end of the lexical scope:
use re "/x";
"foo" =~ / (.+) /; # /x implied
See "'/flags' mode" in re for details.
\o{...} for octals
There is a new octal escape sequence, "\o", in doublequote-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 a
regex capture group. See "Capture groups" in perlre.
Add "\p{Titlecase}" as a synonym for "\p{Title}"
This synonym is added for symmetry with the Unicode property names
"\p{Uppercase}" and "\p{Lowercase}".
Regular expression debugging output improvement
Regular expression debugging output (turned on by "use re 'debug'") now
uses hexadecimal when escaping non-ASCII characters, instead of octal.
Return value of "delete $+{...}"
Custom regular expression engines can now determine the return value of
"delete" on an entry of "%+" or "%-".
Syntactical Enhancements
Array and hash container functions accept references
Warning: This feature is considered experimental, as the exact
behaviour may change in a future version of Perl.
All builtin functions that operate directly on array or hash containers
now also accept unblessed hard references to arrays or hashes:
|----------------------------+---------------------------|
| Traditional syntax | Terse syntax |
|----------------------------+---------------------------|
| push @$arrayref, @stuff | push $arrayref, @stuff |
| unshift @$arrayref, @stuff | unshift $arrayref, @stuff |
| pop @$arrayref | pop $arrayref |
| shift @$arrayref | shift $arrayref |
| splice @$arrayref, 0, 2 | splice $arrayref, 0, 2 |
| keys %$hashref | keys $hashref |
| keys @$arrayref | keys $arrayref |
| values %$hashref | values $hashref |
| values @$arrayref | values $arrayref |
| ($k,$v) = each %$hashref | ($k,$v) = each $hashref |
| ($k,$v) = each @$arrayref | ($k,$v) = each $arrayref |
|----------------------------+---------------------------|
This allows these builtin functions to act on long dereferencing chains
or on the return value of subroutines without needing to wrap them in
"@{}" or "%{}":
push @{$obj->tags}, $new_tag; # old way
push $obj->tags, $new_tag; # new way
for ( keys %{$hoh->{genres}{artists}} ) {...} # old way
for ( keys $hoh->{genres}{artists} ) {...} # new way
Single term prototype
The "+" prototype is a special alternative to "$" that acts like
"\[@%]" when given a literal array or hash variable, but will otherwise
force scalar context on the argument. See "Prototypes" in perlsub.
"package" block syntax
A package declaration can now contain a code block, in which case the
declaration is in scope inside that block only. So "package Foo { ...
}" is precisely equivalent to "{ package Foo; ... }". It also works
with a version number in the declaration, as in "package Foo 1.2 { ...
}", which is its most attractive feature. See perlfunc.
Statement labels can appear in more places
Statement labels can now occur before any type of statement or
declaration, such as "package".
Stacked labels
Multiple statement labels can now appear before a single statement.
Uppercase X/B allowed in hexadecimal/binary literals
Literals may now use either upper case "0X..." or "0B..." prefixes, in
addition to the already supported "0x..." and "0b..." syntax [perl
#76296].
C, Ruby, Python, and PHP already support this syntax, and it makes Perl
more internally consistent: a round-trip with "eval sprintf "%#X",
0x10" now returns 16, just like "eval sprintf "%#x", 0x10".
Overridable tie functions
"tie", "tied" and "untie" can now be overridden [perl #75902].
Exception Handling
To make them more reliable and consistent, several changes have been
made to how "die", "warn", and $@ behave.
o When an exception is thrown inside an "eval", the exception is no
longer at risk of being clobbered by destructor code running during
unwinding. Previously, the exception was written into $@ early in
the throwing process, and would be overwritten if "eval" was used
internally in the destructor for an object that had to be freed
while exiting from the outer "eval". Now the exception is written
into $@ last thing before exiting the outer "eval", so the code
running immediately thereafter can rely on the value in $@
correctly corresponding to that "eval". ($@ is still also set
before exiting the "eval", for the sake of destructors that rely on
this.)
Likewise, a "local $@" inside an "eval" no longer clobbers any
exception thrown in its scope. Previously, the restoration of $@
upon unwinding would overwrite any exception being thrown. Now the
exception gets to the "eval" anyway. So "local $@" is safe before
a "die".
Exceptions thrown from object destructors no longer modify the $@
of the surrounding context. (If the surrounding context was
exception unwinding, this used to be another way to clobber the
exception being thrown.) Previously such an exception was
sometimes emitted as a warning, and then either was string-appended
to the surrounding $@ or completely replaced the surrounding $@,
depending on whether that exception and the surrounding $@ were
strings or objects. Now, an exception in this situation is always
emitted as a warning, leaving the surrounding $@ untouched. In
addition to object destructors, this also affects any function call
run by XS code using the "G_KEEPERR" flag.
o Warnings for "warn" can now be objects in the same way as
exceptions for "die". If an object-based warning gets the default
handling of writing to standard error, it is stringified as before
with the filename and line number appended. But a $SIG{__WARN__}
handler now receives an object-based warning as an object, where
previously it was passed the result of stringifying the object.
Other Enhancements
Assignment to $0 sets the legacy process name with prctl() on Linux
On Linux the legacy process name is now set with prctl(2), in addition
to altering the POSIX name via "argv[0]", as Perl has done since
version 4.000. Now system utilities that read the legacy process name
such as ps, top, and killall recognize the name you set when assigning
to $0. The string you supply is truncated at 16 bytes; this limitation
is imposed by Linux.
srand() now returns the seed
This allows programs that need to have repeatable results not to have
to come up with their own seed-generating mechanism. Instead, they can
use srand() and stash the return value for future use. One example is
a test program with too many combinations to test comprehensively in
the time available for each run. It can test a random subset each time
and, should there be a failure, log the seed used for that run so this
can later be used to produce the same results.
printf-like functions understand post-1980 size modifiers
Perl's printf and sprintf operators, and Perl's internal printf
replacement function, now understand the C90 size modifiers "hh"
("char"), "z" ("size_t"), and "t" ("ptrdiff_t"). Also, when compiled
with a C99 compiler, Perl now understands the size modifier "j"
("intmax_t") (but this is not portable).
So, for example, on any modern machine, "sprintf("%hhd", 257)" returns
"1".
New global variable "${^GLOBAL_PHASE}"
A new global variable, "${^GLOBAL_PHASE}", has been added to allow
introspection of the current phase of the Perl interpreter. It's
explained in detail in "${^GLOBAL_PHASE}" in perlvar and in "BEGIN,
UNITCHECK, CHECK, INIT and END" in perlmod.
"-d:-foo" calls "Devel::foo::unimport"
The syntax -d:foo was extended in 5.6.1 to make -d:foo=bar equivalent
to -MDevel::foo=bar, which expands internally to "use Devel::foo
'bar'". Perl now allows prefixing the module name with -, with the
same semantics as -M; that is:
"-d:-foo"
Equivalent to -M-Devel::foo: expands to "no Devel::foo" and calls
"Devel::foo->unimport()" if that method exists.
"-d:-foo=bar"
Equivalent to -M-Devel::foo=bar: expands to "no Devel::foo 'bar'",
and calls "Devel::foo->unimport("bar")" if that method exists.
This is particularly useful for suppressing the default actions of a
"Devel::*" module's "import" method whilst still loading it for
debugging.
Filehandle method calls load IO::File on demand
When a method call on a filehandle would die because the method cannot
be resolved and IO::File has not been loaded, Perl now loads IO::File
via "require" and attempts method resolution again:
open my $fh, ">", $file;
$fh->binmode(":raw"); # loads IO::File and succeeds
This also works for globs like "STDOUT", "STDERR", and "STDIN":
STDOUT->autoflush(1);
Because this on-demand load happens only if method resolution fails,
the legacy approach of manually loading an IO::File parent class for
partial method support still works as expected:
use IO::Handle;
open my $fh, ">", $file;
$fh->autoflush(1); # IO::File not loaded
Improved IPv6 support
The "Socket" module provides new affordances for IPv6, including
implementations of the "Socket::getaddrinfo()" and
"Socket::getnameinfo()" functions, along with related constants and a
handful of new functions. See Socket.
DTrace probes now include package name
The "DTrace" probes now include an additional argument, "arg3", which
contains the package the subroutine being entered or left was compiled
in.
For example, using the following DTrace script:
perl$target:::sub-entry
{
printf("%s::%s\n", copyinstr(arg0), copyinstr(arg3));
}
and then running:
$ perl -e 'sub test { }; test'
"DTrace" will print:
main::test
New C APIs
See "Internal Changes".
Security
User-defined regular expression properties
"User-Defined Character Properties" in perlunicode documented that you
can create custom properties by defining subroutines whose names begin
with "In" or "Is". However, Perl did not actually enforce that naming
restriction, so "\p{foo::bar}" could call foo::bar() if it existed.
The documented convention is now enforced.
Also, Perl no longer allows tainted regular expressions to invoke a
user-defined property. It simply dies instead [perl #82616].
Incompatible Changes
Perl 5.14.0 is not binary-compatible with any previous stable release.
In addition to the sections that follow, see "C API Changes".
Regular Expressions and String Escapes
Inverted bracketed character classes and multi-character folds
Some characters match a sequence of two or three characters in "/i"
regular expression matching under Unicode rules. One example is "LATIN
SMALL LETTER SHARP S" which matches the sequence "ss".
'ss' =~ /\A[\N{LATIN SMALL LETTER SHARP S}]\z/i # Matches
This, however, can lead to very counter-intuitive results, especially
when inverted. Because of this, Perl 5.14 does not use multi-character
"/i" matching in inverted character classes.
'ss' =~ /\A[^\N{LATIN SMALL LETTER SHARP S}]+\z/i # ???
This should match any sequences of characters that aren't the "SHARP S"
nor what "SHARP S" matches under "/i". "s" isn't "SHARP S", but
Unicode says that "ss" is what "SHARP S" matches under "/i". So which
one "wins"? Do you fail the match because the string has "ss" or accept
it because it has an "s" followed by another "s"?
Earlier releases of Perl did allow this multi-character matching, but
due to bugs, it mostly did not work.
\400-\777
In certain circumstances, "\400"-"\777" in regexes have behaved
differently than they behave in all other doublequote-like contexts.
Since 5.10.1, Perl has issued a deprecation warning when this happens.
Now, these literals behave the same in all doublequote-like contexts,
namely to be equivalent to "\x{100}"-"\x{1FF}", with no deprecation
warning.
Use of "\400"-"\777" in the command-line option -0 retain their
conventional meaning. They slurp whole input files; previously, this
was documented only for -0777.
Because of various ambiguities, you should use the new "\o{...}"
construct to represent characters in octal instead.
Most "\p{}" properties are now immune to case-insensitive matching
For most Unicode properties, it doesn't make sense to have them match
differently under "/i" case-insensitive matching. Doing so can lead to
unexpected results and potential security holes. For example
m/\p{ASCII_Hex_Digit}+/i
could previously match non-ASCII characters because of the Unicode
matching rules (although there were several bugs with this). Now
matching under "/i" gives the same results as non-"/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 "m/\p{Uppercase}/i" and "m/\p{Lowercase}/i", both of which match the
same code points as matched by "m/\p{Cased}/i". Details are in
"Unicode Properties" in perlrecharclass.
User-defined property handlers that need to match differently under
"/i" must be changed to read the new boolean parameter passed to them,
which is non-zero if case-insensitive matching is in effect and 0
otherwise. See "User-Defined Character Properties" in perlunicode.
\p{} implies Unicode semantics
Specifying a Unicode property in the pattern indicates that the pattern
is meant for matching according to Unicode rules, the way "\N{NAME}"
does.
Regular expressions retain their localeness when interpolated
Regular expressions compiled under "use locale" now retain this when
interpolated into a new regular expression compiled outside a "use
locale", and vice-versa.
Previously, one regular expression interpolated into another inherited
the localeness of the surrounding regex, 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 behaviour.
Stringification of regexes has changed
Default regular expression modifiers are now notated using "(?^...)".
Code relying on the old stringification will fail. This is so that
when new modifiers are added, such code won't have to keep changing
each time this happens, because the stringification will 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; see re):
use re qw(regexp_pattern);
my ($pat, $mods) = regexp_pattern($re_ref);
If the actual stringification is important or older Perls need to be
supported, you can use something like the following:
# Accept both old and new-style stringification
my $modifiers = (qr/foobar/ =~ /\Q(?^/) ? "^" : "-xism";
And then use $modifiers instead of "-xism".
Run-time code blocks in regular expressions inherit pragmata
Code blocks in regular expressions ("(?{...})" and "(??{...})")
previously did not inherit pragmata (strict, warnings, etc.) if the
regular expression was compiled at run time as happens in cases like
these two:
use re "eval";
$foo =~ $bar; # when $bar contains (?{...})
$foo =~ /$bar(?{ $finished = 1 })/;
This bug has now been fixed, but code that relied on the buggy
behaviour may need to be fixed to account for the correct behaviour.
Stashes and Package Variables
Localised tied hashes and arrays 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
Earlier versions of Perl incorrectly tied the new local array. This
has now been fixed. This fix could however potentially cause a change
in behaviour of some code.
Stashes are now always defined
"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. The fix drastically reduces hashes' memory
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. "defined %hash" has always exposed an
implementation detail: emptying a hash by deleting all entries from it
does not make "defined %hash" false. Hence "defined %hash" is not
valid code to determine whether an arbitrary hash is empty. Instead,
use the behaviour of an empty %hash always returning false in scalar
context.
Clearing stashes
Stash list assignment "%foo:: = ()" used to make the stash temporarily
anonymous while it was being emptied. Consequently, any of its
subroutines referenced elsewhere would become anonymous, showing up as
"(unknown)" in "caller". They now retain their package names such that
"caller" returns the original sub name if there is still a reference to
its typeglob and "foo::__ANON__" otherwise [perl #79208].
Dereferencing typeglobs
If you assign a typeglob to a scalar variable:
$glob = *foo;
the glob that is copied to $glob is marked with a special flag
indicating that the glob is just a copy. This allows subsequent
assignments to $glob to overwrite the glob. The original glob,
however, is immutable.
Some Perl operators did not distinguish between these two types of
globs. This would result in strange behaviour in edge cases: "untie
$scalar" would not untie the scalar if the last thing assigned to it
was a glob (because it treated it as "untie *$scalar", which unties a
handle). Assignment to a glob slot (such as "*$glob = \@some_array")
would simply assign "\@some_array" to $glob.
To fix this, the "*{}" operator (including its *foo and *$foo forms)
has been modified to make a new immutable glob if its operand is a glob
copy. This allows operators that make a distinction between globs and
scalars to be modified to treat only immutable globs as globs. ("tie",
"tied" and "untie" have been left as they are for compatibility's sake,
but will warn. See "Deprecations".)
This causes an incompatible change in code that assigns a glob to the
return value of "*{}" when that operator was passed a glob copy. Take
the following code, for instance:
$glob = *foo;
*$glob = *bar;
The *$glob on the second line returns a new immutable glob. That new
glob is made an alias to *bar. Then it is discarded. So the second
assignment has no effect.
See <http://rt.perl.org/rt3/Public/Bug/Display.html?id=77810>; for more
detail.
Magic variables outside the main package
In previous versions of Perl, magic variables like $!, %SIG, etc. would
"leak" into other packages. So %foo::SIG could be used to access
signals, "${"foo::!"}" (with strict mode off) to access C's "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.
This has been fixed (or the feature has been removed, depending on how
you see it).
local($_) strips all magic from $_
local() on scalar variables gives them a new value but keeps all their
magic intact. This has proven problematic for the default scalar
variable $_, where perlsub recommends that any subroutine that assigns
to $_ should first localize it. This would throw an exception if $_ is
aliased to a read-only variable, and could in general have various
unintentional side-effects.
Therefore, as an exception to the general rule, local($_) will not only
assign a new value to $_, but also remove all existing magic from it as
well.
Parsing of package and variable names
Parsing the names of packages and package variables has changed:
multiple adjacent pairs of colons, as in "foo::::bar", are now all
treated as package separators.
Regardless of this change, the exact parsing of package separators has
never been guaranteed and is subject to change in future Perl versions.
Changes to Syntax or to Perl Operators
"given" return values
"given" blocks now return the last evaluated expression, or an empty
list if the block was exited by "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 "Return value" in perlsyn for details.
Change in parsing of certain prototypes
Functions declared with the following prototypes now behave correctly
as unary functions:
*
\$ \% \@ \* \&
\[...]
;$ ;*
;\$ ;\% etc.
;\[...]
Due to this bug fix [perl #75904], functions using the "(*)", "(;$)"
and "(;*)" prototypes are parsed with higher precedence than before.
So in the following example:
sub foo(;$);
foo $a < $b;
the second line is now parsed correctly as "foo($a) < $b", rather than
"foo($a < $b)". This happens when one of these operators is used in an
unparenthesised argument:
< > <= >= lt gt le ge
== != <=> eq ne cmp ~~
&
| ^
&&
|| //
.. ...
?:
= += -= *= etc.
, =>
Smart-matching against array slices
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].
Negation treats strings differently from before
The unary negation operator, "-", now treats strings that look like
numbers as numbers [perl #57706].
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
"sprintf("%g", $zero) =~ /^-/" or the Data::Float module on CPAN.
":=" is now a syntax error
Previously "my $pi := 4" was exactly equivalent to "my $pi : = 4", with
the ":" being treated as the start of an attribute list, ending before
the "=". The use of ":=" to mean ": =" was deprecated in 5.12.0, and
is now a syntax error. This allows future use of ":=" as a new token.
Outside the core's tests for it, we find no Perl 5 code on CPAN using
this construction, so we believe that this change will have little
impact on real-world codebases.
If it is absolutely necessary to have empty attribute lists (for
example, because of a code generator), simply avoid the error by adding
a space before the "=".
Change in the parsing of identifiers
Characters outside the Unicode "XIDStart" set are no longer allowed at
the beginning of an identifier. This means that certain accents and
marks that normally follow an alphabetic character may no longer be the
first character of an identifier.
Threads and Processes
Directory handles not copied to threads
On systems other than Windows that do not have a "fchdir" function,
newly-created threads no longer inherit directory handles from their
parent threads. Such programs would usually have crashed anyway [perl
#75154].
"close" on shared pipes
To avoid deadlocks, the "close" function no longer waits for the child
process to exit if the underlying file descriptor is still in use by
another thread. It returns true in such cases.
fork() emulation will not wait for signalled children
On Windows parent processes would not terminate until all forked
children had terminated first. However, "kill("KILL", ...)" is
inherently unstable on pseudo-processes, and "kill("TERM", ...)" might
not get delivered if the child is blocked in a system call.
To avoid the deadlock and still provide a safe mechanism to terminate
the hosting process, Perl now no longer waits for children that have
been sent a SIGTERM signal. It is up to the parent process to
waitpid() for these children if child-cleanup processing must be
allowed to finish. However, it is also then the responsibility of the
parent to avoid the deadlock by making sure the child process can't be
blocked on I/O.
See perlfork for more information about the fork() emulation on
Windows.
Configuration
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 behaviour of Policy.sh if you happen to have been
accidentally relying on its incorrect behaviour.
Perl source code is read in text mode on Windows
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 filehandles have been flushed by a call to system(),
backticks, fork() etc.
The default build options for Windows have been changed to read Perl
source code on Windows in text mode now. ByteLoader will (hopefully)
be updated on CPAN to automatically handle this situation [perl
#28106].
Deprecations
See also "Deprecated C APIs".
Omitting a space between a regular expression and subsequent word
Omitting the space between a regular expression operator or its
modifiers and the following word is deprecated. For example,
"m/foo/sand $bar" is for now still parsed as "m/foo/s and $bar", but
will now issue a warning.
"\cX"
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" could be. Now, a
deprecation warning is raised if that character isn't an ASCII
character. Also, a deprecation warning is raised for "\c{" (which is
the same as simply saying ";").
"\b{" and "\B{"
In regular expressions, a literal "{" immediately following a "\b" (not
in a bracketed character class) or a "\B{" is now deprecated to allow
for its future use by Perl itself.
Perl 4-era .pl libraries
Perl bundles a handful of library files that predate Perl 5. This
bundling is now deprecated for most of these files, which are now
available from CPAN. The affected files now warn when run, if they
were installed as part of the core.
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 versions, of
course, do not generate the warning.
List assignment to $[
Assignment to $[ was deprecated and started to give warnings in Perl
version 5.12.0. This version of Perl (5.14) now also emits a warning
when assigning to $[ in list context. This fixes an oversight in
5.12.0.
Use of qw(...) as parentheses
Historically the parser fooled itself into thinking that "qw(...)"
literals were always enclosed in parentheses, and as a result you could
sometimes omit parentheses around them:
for $x qw(a b c) { ... }
The parser no longer lies to itself in this way. Wrap the list literal
in parentheses like this:
for $x (qw(a b c)) { ... }
This is being deprecated because the parentheses in "for $i (1,2,3) {
... }" are not part of expression syntax. They are part of the
statement syntax, with the "for" statement wanting literal parentheses.
The synthetic parentheses that a "qw" expression acquired were only
intended to be treated as part of expression syntax.
Note that this does not change the behaviour of cases like:
use POSIX qw(setlocale localeconv);
our @EXPORT = qw(foo bar baz);
where parentheses were never required around the expression.
"\N{BELL}"
This is because Unicode is using that name for a different character.
See "Unicode Version 6.0 is now supported (mostly)" for more
explanation.
"?PATTERN?"
"?PATTERN?" (without the initial "m") has been deprecated and now
produces a warning. This is to allow future use of "?" in new
operators. The match-once functionality is still available as
"m?PATTERN?".
Tie functions on scalars holding typeglobs
Calling a tie function ("tie", "tied", "untie") with a scalar argument
acts on a filehandle if the scalar happens to hold a typeglob.
This is a long-standing bug that will be removed in Perl 5.16, as there
is currently no way to tie the scalar itself when it holds a typeglob,
and no way to untie a scalar that has had a typeglob assigned to it.
Now there is a deprecation warning whenever a tie function is used on a
handle without an explicit "*".
User-defined case-mapping
This feature is being deprecated due to its many issues, as documented
in "User-Defined Case Mappings (for serious hackers only)" in
perlunicode. This feature will be removed in Perl 5.16. Instead use
the CPAN module Unicode::Casing, which provides improved functionality.
Deprecated modules
The following module will be removed from the core distribution in a
future release, and should be installed from CPAN instead.
Distributions on CPAN that require this should add it to their
prerequisites. The core version of these module now issues 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 build of Perl with a package for the deprecated module that
installs into "vendor" or "site" Perl library directories. This will
inhibit the deprecation warnings.
Alternatively, you may want to consider patching lib/deprecate.pm to
provide deprecation warnings specific to your packaging system or
distribution of Perl, consistent with how your packaging system or
distribution manages a staged transition from a release where the
installation of a single package provides the given functionality, to a
later release where the system administrator needs to know to install
multiple packages to get that same functionality.
You can silence these deprecation warnings by installing the module in
question from CPAN. To install the latest version of it by role rather
than by name, just install "Task::Deprecations::5_14".
Devel::DProf
We strongly recommend that you install and use Devel::NYTProf
instead of Devel::DProf, as Devel::NYTProf offers significantly
improved profiling and reporting.
Performance Enhancements
"Safe signals" optimisation
Signal dispatch has been moved from the runloop into control ops. This
should give a few percent speed increase, and eliminates nearly all the
speed penalty caused by the introduction of "safe signals" in 5.8.0.
Signals should still be dispatched within the same statement as they
were previously. If this does not happen, or if you find it possible
to create uninterruptible loops, this is a bug, and reports are
encouraged of how to recreate such issues.
Optimisation of shift() and pop() calls without arguments
Two fewer OPs are used for shift() and pop() calls with no argument
(with implicit @_). This change makes shift() 5% faster than "shift
@_" on non-threaded perls, and 25% faster on threaded ones.
Optimisation of regexp engine string comparison work
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.
Regular expression compilation speed-up
Compiling regular expressions has been made faster when upgrading the
regex to utf8 is necessary but this isn't known when the compilation
begins.
String appending is 100 times faster
When doing a lot of string appending, perls built to use the system's
"malloc" could end up allocating a lot more memory than needed in a
inefficient way.
"sv_grow", the function used to allocate more memory if necessary when
appending to a string, has been taught 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.
Eliminate "PL_*" accessor functions under ithreads
When "MULTIPLICITY" was first developed, and interpreter state moved
into an interpreter struct, thread- and interpreter-local "PL_*"
variables were defined as macros that called accessor functions
(returning the address of the value) outside 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.
This mechanism was redundant and penalised well-behaved code. It has
been removed.
Freeing weak references
When there are many weak references to an object, freeing that object
can under some circumstances take O(N*N) time to free, where N is the
number of references. The circumstances in which this can happen have
been reduced [perl #75254]
Lexical array and hash assignments
An earlier optimisation to speed up "my @array = ..." and "my %hash =
..." assignments caused a bug and was disabled in Perl 5.12.0.
Now we have found another way to speed up these assignments [perl
#82110].
@_ uses less memory
Previously, @_ 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].
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 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 are now
calculated on demand, cases when this needs to be done should be rare.
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.
"XPV", "XPVIV", and "XPVNV" now allocate only the parts of the "SV"
body they actually use, saving some space.
Scalars containing regular expressions now allocate only the part of
the "SV" body they actually use, saving some space.
Memory consumption improvements to Exporter
The @EXPORT_FAIL AV is no longer created unless needed, hence neither
is the typeglob backing it. This saves about 200 bytes for every
package that uses Exporter but doesn't use this functionality.
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.
"%+" and "%-" use less memory
The bulk of the "Tie::Hash::NamedCapture" module used to be in the Perl
core. It has now been moved to an XS module to reduce overhead for
programs that do not use "%+" or "%-".
Multiple small improvements to threads
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 they're
done only as needed (although this is only possible for non-debugging
builds).
Adjacent pairs of nextstate opcodes are now optimized away
Previously, in code such as
use constant DEBUG => 0;
sub GAK {
warn if DEBUG;
print "stuff\n";
}
the ops for "warn if DEBUG" would be folded to a "null" op
("ex-const"), but the "nextstate" op would remain, resulting in a
runtime op dispatch of "nextstate", "nextstate", etc.
The execution of a sequence of "nextstate" ops is indistinguishable
from just the last "nextstate" op so the peephole optimizer now
eliminates the first of a pair of "nextstate" ops except when the first
carries a label, since labels must not be eliminated by the optimizer,
and label usage isn't conclusively known at compile time.
Modules and Pragmata
New Modules and Pragmata
o CPAN::Meta::YAML 0.003 has been added as a dual-life module. It
supports a subset of YAML sufficient for reading and writing
META.yml and MYMETA.yml files included with CPAN distributions or
generated by the module installation toolchain. It should not be
used for any other general YAML parsing or generation task.
o CPAN::Meta version 2.110440 has been added as a dual-life module.
It provides a standard library to read, interpret and write CPAN
distribution metadata files (like META.json and META.yml) that
describe a distribution, its contents, and the requirements for
building it and installing it. The latest CPAN distribution
metadata specification is included as CPAN::Meta::Spec and notes on
changes in the specification over time are given in
CPAN::Meta::History.
o HTTP::Tiny 0.012 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 been added so that CPAN.pm and CPANPLUS
can "bootstrap" HTTP access to CPAN using pure Perl without relying
on external binaries like curl(1) or wget(1).
o JSON::PP 2.27105 has been added as a dual-life module to allow CPAN
clients to read META.json files in CPAN distributions.
o 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 favor of this
module instead.
o Perl::OSType 1.002 has been added as a dual-life module. It maps
Perl operating system names (like "dragonfly" or "MSWin32") to more
generic types with standardized names (like "Unix" or "Windows").
It has been refactored out of Module::Build and ExtUtils::CBuilder
and consolidates such mappings into a single location for easier
maintenance.
o The following modules were added by the Unicode::Collate upgrade.
See below for details.
Unicode::Collate::CJK::Big5
Unicode::Collate::CJK::GB2312
Unicode::Collate::CJK::JISX0208
Unicode::Collate::CJK::Korean
Unicode::Collate::CJK::Pinyin
Unicode::Collate::CJK::Stroke
o Version::Requirements version 0.101020 has been added as a dual-
life module. It provides a standard library to model and
manipulates module prerequisites and version constraints defined in
CPAN::Meta::Spec.
Updated Modules and Pragma
o attributes has been upgraded from version 0.12 to 0.14.
o 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(1) executable.
o Archive::Tar has been upgraded from version 1.54 to 1.76.
Important changes since 1.54 include the following:
o Compatibility with busybox implementations of tar(1).
o A fix so that write() and create_archive() close only
filehandles they themselves opened.
o A bug was fixed regarding the exit code of extract_archive.
o The ptar(1) 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.
o A new ptargrep(1) utility for using regular expressions against
the contents of files in a tar archive.
o pax extended headers are now skipped.
o Attribute::Handlers has been upgraded from version 0.87 to 0.89.
o autodie has been upgraded from version 2.06_01 to 2.1001.
o AutoLoader has been upgraded from version 5.70 to 5.71.
o The B module has been upgraded from version 1.23 to 1.29.
It no longer crashes when taking apart a "y///" containing
characters outside the octet range or compiled in a "use utf8"
scope.
The size of the shared object has been reduced by about 40%, with
no reduction in functionality.
o B::Concise has been upgraded from version 0.78 to 0.83.
B::Concise marks rv2sv(), rv2av(), and rv2hv() ops with the new
"OPpDEREF" flag as "DREFed".
It no longer produces mangled output with the -tree option [perl
#80632].
o B::Debug has been upgraded from version 1.12 to 1.16.
o B::Deparse has been upgraded from version 0.96 to 1.03.
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 "%^H" or other state and a label. The label was previously
emitted first, but is now emitted last (5.12.1).
The "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 $_ as it was fixed in [perl #20444].
Deparsing of "our" followed by a variable with funny characters (as
permitted under the "use utf8" pragma) has also been fixed [perl
#33752].
o B::Lint has been upgraded from version 1.11_01 to 1.13.
o base has been upgraded from version 2.15 to 2.16.
o Benchmark has been upgraded from version 1.11 to 1.12.
o bignum has been upgraded from version 0.23 to 0.27.
o Carp has been upgraded from version 1.15 to 1.20.
Carp now detects incomplete caller() overrides and avoids using
bogus @DB::args. To provide backtraces, Carp relies on particular
behaviour of the caller() builtin. 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).
This fixes certain cases of "Bizarre copy of ARRAY" caused by
modules overriding caller() incorrectly (5.12.2).
It now also avoids using regular expressions that cause Perl to
load its Unicode tables, so as to avoid the "BEGIN not safe after
errors" error that ensue if there has been a syntax error [perl
#82854].
o CGI has been upgraded from version 3.48 to 3.52.
This provides the following security fixes: the MIME boundary in
multipart_init() is now random and the handling of newlines
embedded in header values has been improved.
o Compress::Raw::Bzip2 has been upgraded from version 2.024 to 2.033.
It has been updated to use bzip2(1) 1.0.6.
o Compress::Raw::Zlib has been upgraded from version 2.024 to 2.033.
o constant has been upgraded from version 1.20 to 1.21.
Unicode constants work once more. They have been broken since Perl
5.10.0 [CPAN RT #67525].
o CPAN has been upgraded from version 1.94_56 to 1.9600.
Major highlights:
o much less configuration dialog hassle
o support for META/MYMETA.json
o support for local::lib
o support for HTTP::Tiny to reduce the dependency on FTP sites
o automatic mirror selection
o iron out all known bugs in configure_requires
o support for distributions compressed with bzip2(1)
o allow Foo/Bar.pm on the command line to mean "Foo::Bar"
o CPANPLUS has been upgraded from version 0.90 to 0.9103.
A change to cpanp-run-perl resolves RT #55964
<http://rt.cpan.org/Public/Bug/Display.html?id=55964>; and RT #57106
<http://rt.cpan.org/Public/Bug/Display.html?id=57106>;, both of
which related to failures to install distributions that use
"Module::Install::DSL" (5.12.2).
A dependency on Config was not recognised as a core module
dependency. This has been fixed.
CPANPLUS now includes support for META.json and MYMETA.json.
o CPANPLUS::Dist::Build has been upgraded from version 0.46 to 0.54.
o Data::Dumper has been upgraded from version 2.125 to 2.130_02.
The indentation used to be off when $Data::Dumper::Terse was set.
This has been fixed [perl #73604].
This upgrade also fixes a crash when using custom sort functions
that might cause the stack to change [perl #74170].
Dumpxs no longer crashes with globs returned by *$io_ref [perl
#72332].
o DB_File has been upgraded from version 1.820 to 1.821.
o DBM_Filter has been upgraded from version 0.03 to 0.04.
o Devel::DProf has been upgraded from version 20080331.00 to
20110228.00.
Merely loading Devel::DProf now no longer triggers profiling to
start. Both "use Devel::DProf" and "perl -d:DProf ..." behave as
before and start the profiler.
NOTE: Devel::DProf is deprecated and will be removed from a future
version of Perl. We strongly recommend that you install and use
Devel::NYTProf instead, as it offers significantly improved
profiling and reporting.
o Devel::Peek has been upgraded from version 1.04 to 1.07.
o Devel::SelfStubber has been upgraded from version 1.03 to 1.05.
o diagnostics has been upgraded from version 1.19 to 1.22.
It now renders pod links slightly better, and has been taught to
find descriptions for messages that share their descriptions with
other messages.
o Digest::MD5 has been upgraded from version 2.39 to 2.51.
It is now safe to use this module in combination with threads.
o Digest::SHA has been upgraded from version 5.47 to 5.61.
"shasum" now more closely mimics sha1sum(1)/md5sum(1).
"addfile" accepts all POSIX filenames.
New SHA-512/224 and SHA-512/256 transforms (ref. NIST Draft FIPS
180-4 [February 2011])
o DirHandle has been upgraded from version 1.03 to 1.04.
o Dumpvalue has been upgraded from version 1.13 to 1.16.
o DynaLoader has been upgraded from version 1.10 to 1.13.
It fixes a buffer overflow when passed a very long file name.
It no longer inherits from AutoLoader; hence it no longer produces
weird error messages for unsuccessful method calls on classes that
inherit from DynaLoader [perl #84358].
o 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: in cases when it was disallowed, all 66
are disallowed, and in cases where it warned, all 66 warn.
o Env has been upgraded from version 1.01 to 1.02.
o Errno has been upgraded from version 1.11 to 1.13.
The implementation of Errno has been refactored to use about 55%
less memory.
On some platforms with unusual header files, like Win32 gcc(1)
using "mingw64" headers, some constants that weren't actually error
numbers have been exposed by Errno. This has been fixed [perl
#77416].
o Exporter has been upgraded from version 5.64_01 to 5.64_03.
Exporter no longer overrides $SIG{__WARN__} [perl #74472]
o ExtUtils::CBuilder has been upgraded from version 0.27 to 0.280203.
o ExtUtils::Command has been upgraded from version 1.16 to 1.17.
o ExtUtils::Constant has been upgraded from 0.22 to 0.23.
The AUTOLOAD helper code generated by
"ExtUtils::Constant::ProxySubs" can now croak() for missing
constants, or generate a complete "AUTOLOAD" subroutine in XS,
allowing simplification of many modules that use it (Fcntl,
File::Glob, GDBM_File, I18N::Langinfo, POSIX, Socket).
ExtUtils::Constant::ProxySubs can now optionally push the names of
all constants onto the package's @EXPORT_OK.
o ExtUtils::Install has been upgraded from version 1.55 to 1.56.
o ExtUtils::MakeMaker has been upgraded from version 6.56 to 6.57_05.
o ExtUtils::Manifest has been upgraded from version 1.57 to 1.58.
o ExtUtils::ParseXS has been upgraded from version 2.21 to 2.2210.
o Fcntl has been upgraded from version 1.06 to 1.11.
o File::Basename has been upgraded from version 2.78 to 2.82.
o File::CheckTree has been upgraded from version 4.4 to 4.41.
o File::Copy has been upgraded from version 2.17 to 2.21.
o File::DosGlob has been upgraded from version 1.01 to 1.04.
It allows patterns containing literal parentheses: they no longer
need to be escaped. On Windows, it no longer adds an extra ./ to
file names returned when the pattern is a relative glob with a
drive specification, like C:*.pl [perl #71712].
o File::Fetch has been upgraded from version 0.24 to 0.32.
HTTP::Lite is now supported for the "http" scheme.
The fetch(1) utility is supported on FreeBSD, NetBSD, and Dragonfly
BSD for the "http" and "ftp" schemes.
o File::Find has been upgraded from version 1.15 to 1.19.
It improves handling of backslashes on Windows, so that paths like
C:\dir\/file are no longer generated [perl #71710].
o File::Glob has been upgraded from version 1.07 to 1.12.
o File::Spec has been upgraded from version 3.31 to 3.33.
Several portability fixes were made in 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; catpath() returns an empty directory rather than the
current directory if the input directory name is empty; and
abs2rel() properly handles Unix-style input (5.12.2).
o File::stat has been upgraded from 1.02 to 1.05.
The "-x" and "-X" file test operators now work correctly when run
by the superuser.
o Filter::Simple has been upgraded from version 0.84 to 0.86.
o GDBM_File has been upgraded from 1.10 to 1.14.
This fixes a memory leak when DBM filters are used.
o Hash::Util has been upgraded from 0.07 to 0.11.
Hash::Util no longer emits spurious "uninitialized" warnings when
recursively locking hashes that have undefined values [perl
#74280].
o Hash::Util::FieldHash has been upgraded from version 1.04 to 1.09.
o I18N::Collate has been upgraded from version 1.01 to 1.02.
o I18N::Langinfo has been upgraded from version 0.03 to 0.08.
langinfo() now defaults to using $_ if there is no argument given,
just as the documentation has always claimed.
o I18N::LangTags has been upgraded from version 0.35 to 0.35_01.
o if has been upgraded from version 0.05 to 0.0601.
o IO has been upgraded from version 1.25_02 to 1.25_04.
This version of IO includes a new IO::Select, which now allows
IO::Handle objects (and objects in derived classes) to be removed
from an IO::Select set even if the underlying file descriptor is
closed or invalid.
o IPC::Cmd has been upgraded from version 0.54 to 0.70.
Resolves an issue with splitting Win32 command lines. An argument
consisting of the single character "0" used to be omitted (CPAN RT
#62961).
o IPC::Open3 has been upgraded from 1.05 to 1.09.
open3() now produces an error if the "exec" call fails, allowing
this condition to be distinguished from a child process that exited
with a non-zero status [perl #72016].
The internal xclose() routine now knows how to handle file
descriptors as documented, so duplicating "STDIN" in a child
process using its file descriptor now works [perl #76474].
o IPC::SysV has been upgraded from version 2.01 to 2.03.
o lib has been upgraded from version 0.62 to 0.63.
o Locale::Maketext has been upgraded from version 1.14 to 1.19.
Locale::Maketext now supports external caches.
This upgrade also fixes an infinite loop in
"Locale::Maketext::Guts::_compile()" when working with tainted
values (CPAN RT #40727).
"->maketext" calls now back up and restore $@ so error messages are
not suppressed (CPAN RT #34182).
o Log::Message has been upgraded from version 0.02 to 0.04.
o Log::Message::Simple has been upgraded from version 0.06 to 0.08.
o Math::BigInt has been upgraded from version 1.89_01 to 1.994.
This fixes, among other things, incorrect results when computing
binomial coefficients [perl #77640].
It also prevents "sqrt($int)" from crashing under "use bigrat".
[perl #73534].
o Math::BigInt::FastCalc has been upgraded from version 0.19 to 0.28.
o Math::BigRat has been upgraded from version 0.24 to 0.26_02.
o Memoize has been upgraded from version 1.01_03 to 1.02.
o MIME::Base64 has been upgraded from 3.08 to 3.13.
Includes new functions to calculate the length of encoded and
decoded base64 strings.
Now provides encode_base64url() and decode_base64url() functions to
process the base64 scheme for "URL applications".
o Module::Build has been upgraded from version 0.3603 to 0.3800.
A notable change is the deprecation of several modules.
Module::Build::Version has been deprecated and Module::Build now
relies on the version pragma directly. Module::Build::ModuleInfo
has been deprecated in favor of a standalone copy called
Module::Metadata. Module::Build::YAML has been deprecated in favor
of CPAN::Meta::YAML.
Module::Build now also generates META.json and MYMETA.json files in
accordance with version 2 of the CPAN distribution metadata
specification, CPAN::Meta::Spec. The older format META.yml and
MYMETA.yml files are still generated.
o 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 "Filespec" module. That module never existed in
core. The scripts generating Module::CoreList confused it with
VMS::Filespec, which actually is a core module as of Perl 5.8.7.
o Module::Load has been upgraded from version 0.16 to 0.18.
o Module::Load::Conditional has been upgraded from version 0.34 to
0.44.
o The mro pragma has been upgraded from version 1.02 to 1.07.
o NDBM_File has been upgraded from version 1.08 to 1.12.
This fixes a memory leak when DBM filters are used.
o Net::Ping has been upgraded from version 2.36 to 2.38.
o NEXT has been upgraded from version 0.64 to 0.65.
o Object::Accessor has been upgraded from version 0.36 to 0.38.
o ODBM_File has been upgraded from version 1.07 to 1.10.
This fixes a memory leak when DBM filters are used.
o Opcode has been upgraded from version 1.15 to 1.18.
o The overload pragma has been upgraded from 1.10 to 1.13.
"overload::Method" can now handle subroutines that are themselves
blessed into overloaded classes [perl #71998].
The documentation has greatly improved. See "Documentation" below.
o Params::Check has been upgraded from version 0.26 to 0.28.
o The parent pragma has been upgraded from version 0.223 to 0.225.
o Parse::CPAN::Meta has been upgraded from version 1.40 to 1.4401.
The latest Parse::CPAN::Meta can now read YAML and JSON files using
CPAN::Meta::YAML and JSON::PP, which are now part of the Perl core.
o PerlIO::encoding has been upgraded from version 0.12 to 0.14.
o PerlIO::scalar has been upgraded from 0.07 to 0.11.
A read() after a seek() beyond the end of the string no longer
thinks it has data to read [perl #78716].
o PerlIO::via has been upgraded from version 0.09 to 0.11.
o Pod::Html has been upgraded from version 1.09 to 1.11.
o Pod::LaTeX has been upgraded from version 0.58 to 0.59.
o Pod::Perldoc has been upgraded from version 3.15_02 to 3.15_03.
o Pod::Simple has been upgraded from version 3.13 to 3.16.
o POSIX has been upgraded from 1.19 to 1.24.
It now includes constants for POSIX signal constants.
o The re pragma has been upgraded from version 0.11 to 0.18.
The "use re '/flags'" subpragma is new.
The regmust() function used to crash when called on a regular
expression belonging to a pluggable engine. Now it croaks instead.
regmust() no longer leaks memory.
o Safe has been upgraded from version 2.25 to 2.29.
Coderefs returned by reval() and rdo() are now wrapped via
wrap_code_refs() (5.12.1).
This fixes a possible infinite loop when looking for coderefs.
It adds several "version::vxs::*" routines to the default share.
o SDBM_File has been upgraded from version 1.06 to 1.09.
o SelfLoader has been upgraded from 1.17 to 1.18.
It now works in taint mode [perl #72062].
o The sigtrap pragma has been upgraded from version 1.04 to 1.05.
It no longer tries to modify read-only arguments when generating a
backtrace [perl #72340].
o Socket has been upgraded from version 1.87 to 1.94.
See "Improved IPv6 support" above.
o Storable has been upgraded from version 2.22 to 2.27.
Includes performance improvement for overloaded classes.
This adds support for serialising code references that contain
UTF-8 strings correctly. The Storable minor version number changed
as a result, meaning that Storable users who set
$Storable::accept_future_minor to a "FALSE" value will see errors
(see "FORWARD COMPATIBILITY" in Storable for more details).
Freezing no longer gets confused if the Perl stack gets reallocated
during freezing [perl #80074].
o Sys::Hostname has been upgraded from version 1.11 to 1.16.
o Term::ANSIColor has been upgraded from version 2.02 to 3.00.
o Term::UI has been upgraded from version 0.20 to 0.26.
o Test::Harness has been upgraded from version 3.17 to 3.23.
o Test::Simple has been upgraded from version 0.94 to 0.98.
Among many other things, subtests without a "plan" or "no_plan" now
have an implicit done_testing() added to them.
o Thread::Semaphore has been upgraded from version 2.09 to 2.12.
It provides two new methods that give more control over the
decrementing of semaphores: "down_nb" and "down_force".
o Thread::Queue has been upgraded from version 2.11 to 2.12.
o The threads pragma has been upgraded from version 1.75 to 1.83.
o The threads::shared pragma has been upgraded from version 1.32 to
1.37.
o Tie::Hash has been upgraded from version 1.03 to 1.04.
Calling "Tie::Hash->TIEHASH()" used to loop forever. Now it
"croak"s.
o Tie::Hash::NamedCapture has been upgraded from version 0.06 to
0.08.
o Tie::RefHash has been upgraded from version 1.38 to 1.39.
o Time::HiRes has been upgraded from version 1.9719 to 1.9721_01.
o Time::Local has been upgraded from version 1.1901_01 to 1.2000.
o Time::Piece has been upgraded from version 1.15_01 to 1.20_01.
o Unicode::Collate has been upgraded from version 0.52_01 to 0.73.
Unicode::Collate has been updated to use 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:
Unicode::Collate::CJK::Big5 for "zh__big5han" which makes tailoring
of CJK Unified Ideographs in the order of CLDR's big5han ordering.
Unicode::Collate::CJK::GB2312 for "zh__gb2312han" which makes
tailoring of CJK Unified Ideographs in the order of CLDR's
gb2312han ordering.
Unicode::Collate::CJK::JISX0208 which makes tailoring of 6355 kanji
(CJK Unified Ideographs) in the JIS X 0208 order.
Unicode::Collate::CJK::Korean which makes tailoring of CJK Unified
Ideographs in the order of CLDR's Korean ordering.
Unicode::Collate::CJK::Pinyin for "zh__pinyin" which makes
tailoring of CJK Unified Ideographs in the order of CLDR's pinyin
ordering.
Unicode::Collate::CJK::Stroke for "zh__stroke" which makes
tailoring of CJK Unified Ideographs in the order of CLDR's stroke
ordering.
This also sees the switch from using the pure-Perl version of this
module to the XS version.
o Unicode::Normalize has been upgraded from version 1.03 to 1.10.
o Unicode::UCD has been upgraded from version 0.27 to 0.32.
A new function, Unicode::UCD::num(), has been added. This function
returns the numeric value of the string passed it or "undef" if the
string in its entirety has no "safe" numeric value. (For more
detail, and for the definition of "safe", see "num()" in
Unicode::UCD.)
This upgrade also includes several bug fixes:
charinfo()
o It is now updated to Unicode Version 6.0.0 with Corrigendum
#8, excepting that, just as with Perl 5.14, the code point
at U+1F514 has no name.
o Hangul syllable code points have the correct names, and
their decompositions are always output without requiring
Lingua::KO::Hangul::Util to be installed.
o CJK (Chinese-Japanese-Korean) code points U+2A700 to
U+2B734 and U+2B740 to U+2B81D are now properly handled.
o Numeric values are now output for those CJK code points
that have them.
o Names output for code points with multiple aliases are now
the corrected ones.
charscript()
This now correctly returns "Unknown" instead of "undef" for the
script of a code point that hasn't been assigned another one.
charblock()
This now correctly returns "No_Block" instead of "undef" for
the block of a code point that hasn't been assigned to another
one.
o The version pragma has been upgraded from 0.82 to 0.88.
Because of a bug, now fixed, the is_strict() and is_lax() functions
did not work when exported (5.12.1).
o The warnings pragma has been upgraded from version 1.09 to 1.12.
Calling "use warnings" without arguments is now significantly more
efficient.
o The warnings::register pragma has been upgraded from version 1.01
to 1.02.
It is now possible to register warning categories other than the
names of packages using warnings::register. See perllexwarn(1) for
more information.
o XSLoader has been upgraded from version 0.10 to 0.13.
o VMS::DCLsym has been upgraded from version 1.03 to 1.05.
Two bugs have been fixed [perl #84086]:
The symbol table name was lost when tying a hash, due to a thinko
in "TIEHASH". The result was that all tied hashes interacted with
the local symbol table.
Unless a symbol table name had been explicitly specified in the
call to the constructor, querying the special key ":LOCAL" failed
to identify objects connected to the local symbol table.
o The Win32 module has been upgraded from version 0.39 to 0.44.
This release has several new functions: Win32::GetSystemMetrics(),
Win32::GetProductInfo(), Win32::GetOSDisplayName().
The names returned by Win32::GetOSName() and
Win32::GetOSDisplayName() have been corrected.
o XS::Typemap has been upgraded from version 0.03 to 0.05.
Removed Modules and Pragmata
As promised in Perl 5.12.0's release notes, the following modules have
been removed from the core distribution, and if needed should be
installed from CPAN instead.
o Class::ISA has been removed from the Perl core. Prior version was
0.36.
o Pod::Plainer has been removed from the Perl core. Prior version
was 1.02.
o Switch has been removed from the Perl core. Prior version was
2.16.
The removal of Shell has been deferred until after 5.14, as the
implementation of Shell shipped with 5.12.0 did not correctly issue the
warning that it was to be removed from core.
Documentation
New Documentation
perlgpl
perlgpl has been updated to contain GPL version 1, as is included in
the README distributed with Perl (5.12.1).
Perl 5.12.x delta files
The perldelta files for Perl 5.12.1 to 5.12.3 have been added from the
maintenance branch: perl5121delta, perl5122delta, perl5123delta.
perlpodstyle
New style guide for POD documentation, split mostly from the NOTES
section of the pod2man(1) manpage.
perlsource, perlinterp, perlhacktut, and perlhacktips
See "perlhack and perlrepository revamp", below.
Changes to Existing Documentation
perlmodlib is now complete
The perlmodlib manpage that came with Perl 5.12.0 was missing several
modules due to a bug in the script that generates the list. This has
been fixed [perl #74332] (5.12.1).
Replace incorrect tr/// table in perlebcdic
perlebcdic contains a helpful table to use in "tr///" to convert
between EBCDIC and Latin1/ASCII. 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 been corrected and the sample code changed to correspond.
The table has also been changed to hex from octal, and the recipes in
the pod have been altered to print out leading zeros to make all values
the same length.
Tricks for user-defined casing
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's.
INSTALL explicitly states that Perl requires a C89 compiler
This was already true, but it's now Officially Stated For The Record
(5.12.2).
Explanation of "\xHH" and "\oOOO" escapes
perlop has been updated with more detailed explanation of these two
character escapes.
-0NNN switch
In perlrun, the behaviour of the -0NNN switch for -0400 or higher has
been clarified (5.12.2).
Maintenance policy
perlpolicy now contains the policy on what patches are acceptable for
maintenance branches (5.12.1).
Deprecation policy
perlpolicy now contains the policy on compatibility and deprecation
along with definitions of terms like "deprecation" (5.12.2).
New descriptions in perldiag
The following existing diagnostics are now documented:
o Ambiguous use of %c resolved as operator %c
o Ambiguous use of %c{%s} resolved to %c%s
o Ambiguous use of %c{%s[...]} resolved to %c%s[...]
o Ambiguous use of %c{%s{...}} resolved to %c%s{...}
o Ambiguous use of -%s resolved as -&%s()
o Invalid strict version format (%s)
o Invalid version format (%s)
o Invalid version object
perlbook
perlbook has been expanded to cover many more popular books.
"SvTRUE" macro
The documentation for the "SvTRUE" macro in perlapi was simply wrong in
stating that get-magic is not processed. It has been corrected.
op manipulation functions
Several API functions that process optrees have been newly documented.
perlvar revamp
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. perlvar also has a new section for deprecated variables to
note when they were removed.
Array and hash slices in scalar context
These are now documented in perldata.
"use locale" and formats
perlform and perllocale have been corrected to state that "use locale"
affects formats.
overload
overload's documentation has practically undergone a rewrite. It is
now much more straightforward and clear.
perlhack and perlrepository revamp
The 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, perlsource,
perlinterp, perlhacktut, and perlhacktips. This technical content has
been only lightly edited.
The perlrepository document has been renamed to 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.
Time::Piece examples
Examples in perlfaq4 have been updated to show the use of Time::Piece.
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 perldiag.
New Diagnostics
New Errors
Closure prototype called
This error occurs when a subroutine reference passed to an
attribute handler is called, if the subroutine is a closure [perl
#68560].
Insecure user-defined property %s
Perl detected tainted data when trying to compile a regular
expression that contains a call to a user-defined character
property function, meaning "\p{IsFoo}" or "\p{InFoo}". See "User-
Defined Character Properties" in perlunicode and perlsec.
panic: gp_free failed to free glob pointer - something is repeatedly
re-creating entries
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 etc.
Parsing code internal error (%s)
This new fatal error is produced when parsing code supplied by an
extension violates the parser's API in a detectable way.
refcnt: fd %d%s
This new error only occurs if a internal consistency check fails
when a pipe is about to be closed.
Regexp modifier "/%c" may not appear twice
The regular expression pattern has one of the mutually exclusive
modifiers repeated.
Regexp modifiers "/%c" and "/%c" are mutually exclusive
The regular expression pattern has more than one of the mutually
exclusive modifiers.
Using !~ with %s doesn't make sense
This error occurs when "!~" is used with "s///r" or "y///r".
New Warnings
"\b{" is deprecated; use "\b\{" instead
"\B{" is deprecated; use "\B\{" instead
Use of an unescaped "{" immediately following a "\b" or "\B" is now
deprecated in order to reserve its use for Perl itself in a future
release.
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 this warning.
Use of qw(...) as parentheses is deprecated
See "Use of qw(...) as parentheses", above, for details.
Changes to Existing Diagnostics
o The "Variable $foo is not imported" warning that precedes a "strict
'vars'" error has now been assigned the "misc" category, so that
"no warnings" will suppress it [perl #73712].
o warn() and die() now produce "Wide character" warnings when fed a
character outside the byte range if "STDERR" is a byte-sized
handle.
o The "Layer does not match this perl" error message has been
replaced with these more helpful messages [perl #73754]:
o PerlIO layer function table size (%d) does not match size
expected by this perl (%d)
o PerlIO layer instance size (%d) does not match size expected by
this perl (%d)
o 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 "use
constant", since the value of the constant may not be known at the
time the program is written [perl #77762].
o Previously, if none of the gethostbyaddr(), gethostbyname() and
gethostent() functions were implemented on a given platform, they
would all die with the message "Unsupported socket function
'gethostent' called", with analogous messages for getnet*() and
getserv*(). This has been corrected.
o The warning message about unrecognized regular expression escapes
passed through has been changed to include any literal "{"
following the two-character escape. For example, "\q{" is now
emitted instead of "\q".
Utility Changes
perlbug(1)
o perlbug now looks in the EMAIL environment variable for a return
address if the REPLY-TO and REPLYTO variables are empty.
o perlbug did not previously generate a "From:" header, potentially
resulting in dropped mail; it now includes that header.
o 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 AT 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].
o perlbug now always gives the reporter a chance to change the email
address it guesses for them (5.12.2).
o perlbug should no longer warn about uninitialized values when using
the -d and -v options (5.12.2).
perl5db.pl
o The remote terminal works after forking and spawns new sessions,
one per forked process.
ptargrep
o ptargrep is a new utility to apply pattern matching to the contents
of files in a tar archive. It comes with "Archive::Tar".
Configuration and Compilation
See also "Naming fixes in Policy_sh.SH may invalidate Policy.sh",
above.
o 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.
o "make test.valgrind" has been adjusted to account for cpan/dist/ext
separation.
o On compilers that support it, -Wwrite-strings is now added to
cflags by default.
o The 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.
o 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 by around 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:
./Configure -Accflags=-DPERLIOBUF_DEFAULT_BUFSIZ=N
where N is the desired size in bytes; it should probably be a
multiple of your page size.
o An "incompatible operand types" error in ternary expressions when
building with "clang" has been fixed (5.12.2).
o Perl now skips setuid File::Copy tests on partitions it detects
mounted as "nosuid" (5.12.2).
Platform Support
New Platforms
AIX Perl now builds on AIX 4.2 (5.12.1).
Discontinued Platforms
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.
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.
Platform-Specific Notes
AIX
o README.aix has been updated with information about the XL C/C++ V11
compiler suite (5.12.2).
ARM
o The "d_u32align" configuration probe on ARM has been fixed
(5.12.2).
Cygwin
o MakeMaker has been updated to build manpages on cygwin.
o Improved rebase behaviour
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
http://www.tishler.net/jason/software/rebase/rebase-2.4.2.README
<http://www.tishler.net/jason/software/rebase/rebase-2.4.2.README>;
for more information.
o Support for the standard cygwin dll prefix (needed for FFIs)
o Updated build hints file
FreeBSD 7
o FreeBSD 7 no longer contains /usr/bin/objformat. At build time,
Perl now skips the objformat check for versions 7 and higher and
assumes ELF (5.12.1).
HP-UX
o Perl now allows -Duse64bitint without promoting to "use64bitall" on
HP-UX (5.12.1).
IRIX
o Conversion of strings to floating-point numbers is now more
accurate on IRIX systems [perl #32380].
Mac OS X
o Early versions of Mac OS X (Darwin) had buggy implementations of
the setregid(), setreuid(), setrgid(,) and 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].
MirBSD
o 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. Path
handling is now treated as in the other BSD dialects.
NetBSD
o The NetBSD hints file has been changed to make the system malloc
the default.
OpenBSD
o OpenBSD > 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].
OpenVOS
o Perl now builds again with OpenVOS (formerly known as Stratus VOS)
[perl #78132] (5.12.3).
Solaris
o DTrace is now supported on Solaris. There used to be build
failures, but these have been fixed [perl #73630] (5.12.3).
VMS
o Extension building on older (pre 7.3-2) VMS systems was broken
because configure.com hit the DCL symbol length limit of 1K. We
now work within this limit when assembling the list of extensions
in the core build (5.12.1).
o We fixed configuring and building Perl with -Uuseperlio (5.12.1).
o "PerlIOUnix_open" now honours the default permissions on VMS.
When "perlio" became the default and "unix" became the default
bottom layer, the most common path for creating files from Perl
became "PerlIOUnix_open", which has always explicitly used 0666 as
the permission mask. This prevents inheriting permissions from RMS
defaults and ACLs, so to avoid that problem, we now pass 0777 to
open(). In the VMS CRTL, 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).
o The shortening of symbols longer than 31 characters in the core C
sources and in extensions is now by default done by the C compiler
rather than by xsubpp (which could only do so for generated symbols
in XS code). You can reenable xsubpp's symbol shortening by
configuring with -Uuseshortenedsymbols, but you'll have some work
to do to get the core sources to compile.
o 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.
o 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).
o Several memory leaks in stat() have been fixed (5.12.2).
o A memory leak in Perl_rename() due to a double allocation has been
fixed (5.12.2).
o A memory leak in vms_fid_to_name() (used by realpath() and
realname()> has been fixed (5.12.2).
Windows
See also "fork() emulation will not wait for signalled children" and
"Perl source code is read in text mode on Windows", above.
o Fixed build process for SDK2003SP1 compilers.
o Compilation with Visual Studio 2010 is now supported.
o When using old 32-bit compilers, the define "_USE_32BIT_TIME_T" is
now set in $Config{ccflags}. This improves portability when
compiling XS extensions using new compilers, but for a Perl
compiled with old 32-bit compilers.
o $Config{gccversion} is now set correctly when Perl is built using
the mingw64 compiler from <http://mingw64.org>; [perl #73754].
o When building Perl with the mingw64 x64 cross-compiler "incpath",
"libpth", "ldflags", "lddlflags" and "ldflags_nolargefiles" values
in Config.pm and Config_heavy.pl were not previously being set
correctly because, with that compiler, the include and lib
directories are not immediately below "$(CCHOME)" (5.12.2).
o The build process proceeds more smoothly with mingw and dmake when
C:\MSYS\bin is in the PATH, due to a "Cwd" fix.
o Support for building with Visual C++ 2010 is now underway, but is
not yet complete. See README.win32 or perlwin32 for more details.
o The option to use an externally-supplied crypt(), or to build with
no crypt() at all, has been removed. Perl supplies its own crypt()
implementation for Windows, and the political situation that
required this part of the distribution to sometimes be omitted is
long gone.
Internal Changes
New APIs
CLONE_PARAMS structure added to ease correct thread creation
Modules that create threads should now create "CLONE_PARAMS" structures
by calling the new function Perl_clone_params_new(), and free them with
Perl_clone_params_del(). This will ensure compatibility with any
future changes to the internals of the "CLONE_PARAMS" structure layout,
and that it is correctly allocated and initialised.
New parsing functions
Several functions have been added for parsing Perl statements and
expressions. These functions are meant to be used by XS code invoked
during Perl parsing, in a recursive-descent manner, to allow modules to
augment the standard Perl syntax.
o parse_stmtseq() parses a sequence of statements, up to closing
brace or EOF.
o parse_fullstmt() parses a complete Perl statement, including
optional label.
o parse_barestmt() parses a statement without a label.
o parse_block() parses a code block.
o parse_label() parses a statement label, separate from statements.
o "parse_fullexpr()", "parse_listexpr()", "parse_termexpr()", and
"parse_arithexpr()" parse expressions at various precedence levels.
Hints hash API
A new C API for introspecting the hinthash "%^H" at runtime has been
added. See "cop_hints_2hv", "cop_hints_fetchpvn",
"cop_hints_fetchpvs", "cop_hints_fetchsv", and "hv_copy_hints_hv" in
perlapi for details.
A new, experimental API has been added for accessing the internal
structure that Perl uses for "%^H". See the functions beginning with
"cophh_" in perlapi.
C interface to caller()
The "caller_cx" function has been added as an XSUB-writer's equivalent
of caller(). See perlapi for details.
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
at compile time (specifically as part of op checking) to change the op
tree of that subroutine. The compile-time check function (supplied by
the extension module) can implement argument processing that can't be
expressed as a prototype, generate customised compile-time warnings,
perform constant folding for a pure function, inline a subroutine
consisting of sufficiently simple ops, replace the whole call with a
custom op, and so on. This was previously all possible by hooking the
"entersub" op checker, but the new mechanism makes it easy to tie the
hook to a specific subroutine. See "cv_set_call_checker" in perlapi.
To help in writing custom check hooks, several subtasks within standard
"entersub" op checking have been separated out and exposed in the API.
Improved support for custom OPs
Custom ops can now be registered with the new "custom_op_register" C
function and the "XOP" structure. This will make it easier to add new
properties of custom ops in the future. Two new properties have been
added already, "xop_class" and "xop_peep".
"xop_class" is one of the OA_*OP constants. It allows B and other
introspection mechanisms to work with custom ops that aren't BASEOPs.
"xop_peep" is a pointer to a function that will be called for ops of
this type from "Perl_rpeep".
See "Custom Operators" in perlguts and "Custom Operators" in perlapi
for more detail.
The old "PL_custom_op_names"/"PL_custom_op_descs" interface is still
supported but discouraged.
Scope hooks
It is now possible for XS code to hook into Perl's lexical scope
mechanism at compile time, using the new "Perl_blockhook_register"
function. See "Compile-time scope hooks" in perlguts.
The recursive part of the peephole optimizer is now hookable
In addition to "PL_peepp", for hooking into the toplevel peephole
optimizer, a "PL_rpeepp" is now available to hook into the optimizer
recursing into side-chains of the optree.
New non-magical variants of existing functions
The following functions/macros have been added to the API. The *_nomg
macros are equivalent to their non-"_nomg" variants, except that they
ignore get-magic. Those ending in "_flags" 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
In some of these cases, the non-"_flags" functions have been replaced
with wrappers around the new functions.
pv/pvs/sv versions of existing functions
Many functions ending with pvn now have equivalent "pv/pvs/sv"
versions.
List op-building functions
List op-building functions have been added to the API. See
op_append_elem, op_append_list, and op_prepend_elem in perlapi.
"LINKLIST"
The LINKLIST macro, part of op building that constructs the execution-
order op chain, has been added to the API.
Localisation functions
The "save_freeop", "save_op", "save_pushi32ptr" and "save_pushptrptr"
functions have been added to the API.
Stash names
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 "HvENAME"
macro, which is now the recommended name to use in MRO linearisations
("HvNAME" being a fallback if there is no "HvENAME").
These names are added and deleted via "hv_ename_add" and
"hv_ename_delete". These two functions are not part of the API.
New functions for finding and removing magic
The "mg_findext()" and "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 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 "MAGIC" pointers of an "SV" to find
the magic that belongs to them.
"find_rundefsv"
This function returns the SV representing $_, whether it's lexical or
dynamic.
"Perl_croak_no_modify"
Perl_croak_no_modify() is short-hand for "Perl_croak("%s",
PL_no_modify)".
"PERL_STATIC_INLINE" define
The "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
"static".
"HAS_STATIC_INLINE" can be used to check if the compiler actually
supports inline functions.
New "pv_escape" option for hexadecimal escapes
A new option, "PERL_PV_ESCAPE_NONASCII", has been added to "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.
"lex_start"
"lex_start" has been added to the API, but is considered experimental.
op_scope() and op_lvalue()
The op_scope() and op_lvalue() functions have been added to the API,
but are considered experimental.
C API Changes
"PERL_POLLUTE" has been removed
The option to define "PERL_POLLUTE" to expose older 5.005 symbols for
backwards compatibility has been removed. Its 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).
Check API compatibility when loading XS modules
When Perl's API changes in incompatible ways (which usually happens
between major releases), XS modules compiled for previous versions of
Perl will no longer work. They need to be recompiled against the new
Perl.
The "XS_APIVERSION_BOOTCHECK" macro has been added to ensure that
modules are recompiled and to prevent users from accidentally loading
modules compiled for old perls into newer perls. 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.
Perl_fetch_cop_label
The first argument of the C API function "Perl_fetch_cop_label" has
changed from "struct refcounted_he *" to "COP *", to insulate the user
from implementation details.
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.)
GvCV() and GvGP() are no longer lvalues
The new GvCV_set() and GvGP_set() macros are now provided to replace
assignment to those two macros.
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.
CvGV() is no longer an lvalue
Under some circumstances, the CvGV() field of a CV is now reference-
counted. To ensure consistent behaviour, direct assignment to it, for
example "CvGV(cv) = gv" is now a compile-time error. A new macro,
"CvGV_set(cv,gv)" has been introduced to run 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).
CvSTASH() is no longer an lvalue
The CvSTASH() macro can now only be used as an rvalue. CvSTASH_set()
has been added to replace assignment to CvSTASH(). This is to ensure
that backreferences are handled properly. These macros are not part of
the API.
Calling conventions for "newFOROP" and "newWHILEOP"
The way the parser handles labels has been cleaned up and refactored.
As a result, the newFOROP() constructor function no longer takes a
parameter stating what label is to go in the state op.
The newWHILEOP() and newFOROP() functions no longer accept a line
number as a parameter.
Flags passed to "uvuni_to_utf8_flags" and "utf8n_to_uvuni"
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 perlapi. Code that requires the problematic code 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 "UNICODE_ALLOW_FDD0",
"UNICODE_ALLOW_FFFF", "UNICODE_ILLEGAL", and "UNICODE_IS_ILLEGAL" have
been removed, as they stem from a fundamentally broken model of how the
Unicode non-character code points should be handled, which is now
described in "Non-character code points" in perlunicode. See also the
Unicode section under "Selected Bug Fixes".
Deprecated C APIs
"Perl_ptr_table_clear"
"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.
"sv_compile_2op"
The 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.
"find_rundefsvoffset"
The "find_rundefsvoffset" function has been deprecated. It
appeared that its design was insufficient for reliably getting the
lexical $_ at run-time.
Use the new "find_rundefsv" function or the "UNDERBAR" macro
instead. They directly return the right SV representing $_,
whether it's lexical or dynamic.
"CALL_FPTR" and "CPERLscope"
Those are left from an old implementation of "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 "XS" code.
Only extensions defining "PERL_CORE" must be updated now.
Other Internal Changes
Stack unwinding
The protocol for unwinding the C stack at the last stage of a "die" has
changed how it identifies the target stack frame. This now uses a
separate variable "PL_restartjmpenv", where previously it relied on the
"blk_eval.cur_top_env" pointer in the "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.
Scope stack entries
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.
Memory allocation for pointer tables
Memory allocation for pointer tables has been changed. Previously
"Perl_ptr_table_store" allocated memory from the same arena system as
"SV" bodies and "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 "Perl_ptr_table_free" is called. Additionally,
allocation and release are both less CPU intensive.
"UNDERBAR"
The "UNDERBAR" macro now calls "find_rundefsv". "dUNDERBAR" is now a
noop but should still be used to ensure past and future compatibility.
String comparison routines renamed
The "ibcmp_*" functions have been renamed and are now called "foldEQ",
"foldEQ_locale", and "foldEQ_utf8". The old names are still available
as macros.
"chop" and "chomp" implementations merged
The opcode bodies for "chop" and "chomp" and for "schop" and "schomp"
have been merged. The implementation functions Perl_do_chop() and
Perl_do_chomp(), never part of the public API, have been merged and
moved to a static function in 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 "chomp" is passed a list of
values).
Selected Bug Fixes
I/O
o Perl no longer produces this warning:
$ perl -we 'open(my $f, ">", \my $x); binmode($f, "scalar")'
Use of uninitialized value in binmode at -e line 1.
o Opening a glob reference via "open($fh, ">", \*glob)" no longer
causes 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].
o PerlIO no longer crashes when called recursively, such as from a
signal handler. Now it just leaks memory [perl #75556].
o Most I/O functions were not warning for unopened handles unless the
"closed" and "unopened" warnings categories were both enabled. Now
only "use warnings 'unopened'" is necessary to trigger these
warnings, as had always been the intention.
o There have been several fixes to PerlIO layers:
When "binmode(FH, ":crlf")" pushes the ":crlf" layer on top of the
stack, it no longer enables crlf layers lower in the stack so as to
avoid unexpected results [perl #38456].
Opening a file in ":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].
The three layers ":pop", ":utf8", and ":bytes" didn't allow
stacking when opening a file. For example this:
open(FH, ">:pop:perlio", "some.file") or die $!;
would throw an "Invalid argument" error. This has been fixed in
this release [perl #82484].
Regular Expression Bug Fixes
o The regular expression engine no longer loops when matching
""\N{LATIN SMALL LIGATURE FF}" =~ /f+/i" and similar expressions
[perl #72998] (5.12.1).
o The trie runtime code should no longer allocate massive amounts of
memory, fixing #74484.
o Syntax errors in "(?{...})" blocks no longer cause panic messages
[perl #2353].
o A pattern like "(?:(o){2})?" no longer causes a "panic" error [perl
#39233].
o A fatal error in regular expressions containing "(.*?)" when
processing UTF-8 data has been fixed [perl #75680] (5.12.2).
o An erroneous regular expression engine optimisation that caused
regex verbs like *COMMIT sometimes to be ignored has been removed.
o The regular expression bracketed character class "[\8\9]" was
effectively the same as "[89\000]", incorrectly matching a NULL
character. It also gave incorrect warnings that the 8 and 9 were
ignored. Now "[\8\9]" is the same as "[89]" and gives legitimate
warnings that "\8" and "\9" are unrecognized escape sequences,
passed-through.
o A regular expression match in the right-hand side of a global
substitution ("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 "s|(.)|@a{ print($1),
/./ }|g" [perl #19078].
o 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 "\w" and "\W" [perl #78464] [perl
#18281] [perl #60156].
o Matching a Unicode character against an alternation containing
characters that happened to match continuation bytes in the
former's UTF8 representation (like "qq{\x{30ab}} =~ /\xab|\xa9/")
would cause erroneous warnings [perl #70998].
o The trie optimisation was not taking empty groups into account,
preventing "foo" from matching "/\A(?:(?:)foo|bar|zot)\z/" [perl
#78356].
o A pattern containing a "+" inside a lookahead would sometimes cause
an incorrect match failure in a global match (for example,
"/(?=(\S+))/g") [perl #68564].
o A regular expression optimisation would sometimes cause a match
with a "{n,m}" quantifier to fail when it should have matched [perl
#79152].
o Case-insensitive matching in regular expressions compiled under
"use locale" now works much more sanely when the pattern or target
string is internally encoded 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.
o The "(?|...)" 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].
o A bug has been fixed in the implementation of "{...}" quantifiers
in regular expressions that prevented the code block in "/((\w+)(?{
print $2 })){2}/" from seeing the $2 sometimes [perl #84294].
Syntax/Parsing Bugs
o "when (scalar) {...}" no longer crashes, but produces a syntax
error [perl #74114] (5.12.1).
o A label right before a string eval ("foo: eval $string") no longer
causes the label to be associated also with the first statement
inside the eval [perl #74290] (5.12.1).
o The "no 5.13.2" form of "no" no longer tries to turn on features or
pragmata (like strict) [perl #70075] (5.12.2).
o "BEGIN {require 5.12.0}" now behaves as documented, rather than
behaving identically to "use 5.12.0". Previously, "require" in a
"BEGIN" block was erroneously executing the "use feature ':5.12.0'"
and "use strict" behaviour, which only "use" was documented to
provide [perl #69050].
o A regression introduced in Perl 5.12.0, making "my $x = 3; $x =
length(undef)" result in $x set to 3 has been fixed. $x will now
be "undef" [perl #85508] (5.12.2).
o When strict "refs" mode is off, "%{...}" in rvalue context returns
"undef" if its argument is undefined. An optimisation introduced
in Perl 5.12.0 to make "keys %{...}" faster when used as a boolean
did not take this into account, causing "keys %{+undef}" (and "keys
%$foo" when $foo is undefined) to be an error, which it should be
so in strict mode only [perl #81750].
o Constant-folding used to cause
$text =~ ( 1 ? /phoo/ : /bear/)
to turn into
$text =~ /phoo/
at compile time. Now it correctly matches against $_ [perl
#20444].
o Parsing Perl code (either with string "eval" or by loading modules)
from within a "UNITCHECK" block no longer causes the interpreter to
crash [perl #70614].
o String "eval"s no longer fail after 2 billion scopes have been
compiled [perl #83364].
o The parser no longer hangs when encountering certain Unicode
characters, such as U+387 [perl #74022].
o Defining a constant with the same name as one of Perl's special
blocks (like "INIT") stopped working in 5.12.0, but has now been
fixed [perl #78634].
o A reference to a literal value used as a hash key ($hash{\"foo"})
used to be stringified, even if the hash was tied [perl #79178].
o A closure containing an "if" statement followed by a constant or
variable is no longer treated as a constant [perl #63540].
o "state" can now be used with attributes. It used to mean the same
thing as "my" if any attributes were present [perl #68658].
o Expressions like "@$a > 3" no longer cause $a to be mentioned in
the "Use of uninitialized value in numeric gt" warning when $a is
undefined (since it is not part of the ">" expression, but the
operand of the "@") [perl #72090].
o 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:
*d = *a; print $d[0];
undef *d; print $d[0];
o The -C command-line option, when used on the shebang line, can now
be followed by other options [perl #72434].
o The "B" module was returning "B::OP"s instead of "B::LOGOP"s for
"entertry" [perl #80622]. This was due to a bug in the Perl core,
not in "B" itself.
Stashes, Globs and Method Lookup
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:
o 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.
Aliasing packages by assigning to globs [perl #77358]
Deleting packages by deleting their containing stash elements
Undefining the glob containing a package ("undef *Foo::")
Undefining an ISA glob ("undef *Foo::ISA")
Deleting an ISA stash element ("delete $Foo::{ISA}")
Sharing @ISA arrays between classes (via "*Foo::ISA = \@Bar::ISA"
or "*Foo::ISA = *Bar::ISA") [perl #77238]
"undef *Foo::ISA" would even stop a new @Foo::ISA array from
updating caches.
o Typeglob assignments would crash if the glob's stash no longer
existed, so long as the glob assigned to were named "ISA" or the
glob on either side of the assignment contained a subroutine.
o "PL_isarev", which is accessible to Perl via "mro::get_isarev" is
now updated properly when packages are deleted or removed from the
@ISA of other classes. This allows many packages to be created and
deleted without causing a memory leak [perl #75176].
In addition, various other bugs related to typeglobs and stashes have
been fixed:
o 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 (for example, <%FOO:: = ()>), and complex typeglob or code-
reference aliasing, will no longer crash the interpreter.
o 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].
o 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;
}
o Assigning a glob to a PVLV used to convert it to a plain string.
Now it works correctly, and a PVLV can hold a glob. This would
happen when a nonexistent hash or array element was passed to a
subroutine:
sub { $_[0] = *foo }->($hash{key});
# $_[0] would have been the string "*main::foo"
It also happened when a glob was assigned to, or returned from, an
element of a tied array or hash [perl #36051].
o When trying to report "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,
"delete $::{"Foo::"}". This has been fixed by disabling the
reporting of variable names in those cases.
o 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:
local *@;
eval { die bless [] }; # puts an object in $@
sub DESTROY {
local $@; # boom
}
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.
o If a typeglob is freed while a subroutine attached to it is still
referenced elsewhere, the subroutine is renamed to "__ANON__" in
the same package, unless the package has been undefined, in which
case the "__ANON__" package is used. This could cause packages to
be sometimes autovivified, such as if the package had been deleted.
Now this no longer occurs. The "__ANON__" package is also now used
when the original package is no longer attached to the symbol
table. This avoids memory leaks in some cases [perl #87664].
o Subroutines and package variables inside a package whose name ends
with "::" can now be accessed with a fully qualified name.
Unicode
o What has become known as "the Unicode Bug" is almost completely
resolved in this release. Under "use feature 'unicode_strings'"
(which is automatically selected by "use 5.012" and above), the
internal storage format of a string no longer affects the external
semantics. [perl #58182].
There are two known exceptions:
1. The now-deprecated, user-defined case-changing functions
require utf8-encoded strings to operate. The CPAN module
Unicode::Casing has been written to replace this feature
without its drawbacks, and the feature is scheduled to be
removed in 5.16.
2. quotemeta() (and its in-line equivalent "\Q") can also give
different results depending on whether a string is encoded in
UTF-8. See "The "Unicode Bug"" in perlunicode.
o Handling of Unicode non-character code points has changed.
Previously they were mostly considered illegal, except that in some
place only one of the 66 of them was known. The Unicode Standard
considers them all legal, but forbids their "open interchange".
This is part of the change to allow internal use of any code point
(see "Core Enhancements"). Together, these changes resolve [perl
#38722], [perl #51918], [perl #51936], and [perl #63446].
o Case-insensitive "/i" regular expression matching of Unicode
characters that match multiple characters now works much more as
intended. For example
"\N{LATIN SMALL LIGATURE FFI}" =~ /ffi/ui
and
"ffi" =~ /\N{LATIN SMALL LIGATURE FFI}/ui
are both true. Previously, there were many bugs with this feature.
What hasn't been fixed are the places where the pattern contains
the multiple characters, but the characters are split up by other
things, such as in
"\N{LATIN SMALL LIGATURE FFI}" =~ /(f)(f)i/ui
or
"\N{LATIN SMALL LIGATURE FFI}" =~ /ffi*/ui
or
"\N{LATIN SMALL LIGATURE FFI}" =~ /[a-f][f-m][g-z]/ui
None of these match.
Also, this matching doesn't fully conform to the current Unicode
Standard, which asks that the matching be made upon the NFD
(Normalization Form Decomposed) of the text. However, as of this
writing (April 2010), the Unicode Standard is currently in flux
about what they will recommend doing with regard in such scenarios.
It may be that they will throw out the whole concept of multi-
character matches. [perl #71736].
o Naming a deprecated character in "\N{NAME}" no longer leaks memory.
o We fixed a bug that could cause "\N{NAME}" constructs followed by a
single "." to be parsed incorrectly [perl #74978] (5.12.1).
o "chop" now correctly handles characters above "\x{7fffffff}" [perl
#73246].
o Passing to "index" an offset beyond the end of the string when the
string is encoded internally in UTF8 no longer causes panics [perl
#75898].
o warn() and die() now respect utf8-encoded scalars [perl #45549].
o Sometimes the UTF8 length cache would not be reset on a value
returned by substr, causing "length(substr($uni_string, ...))" to
give wrong answers. With "${^UTF8CACHE}" set to -1, it would also
produce a "panic" error message [perl #77692].
Ties, Overloading and Other Magic
o Overloading now works properly in conjunction with tied variables.
What formerly happened was that most ops checked their arguments
for overloading before checking for magic, so for example an
overloaded object returned by a tied array access would usually be
treated as not overloaded [RT #57012].
o Various instances of magic (like tie methods) being called on tied
variables too many or too few times have been fixed:
o "$tied->()" did not always call FETCH [perl #8438].
o Filetest operators and "y///" and "tr///" were calling FETCH
too many times.
o The "=" 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].
o Dereference operators used to ignore magic if the argument was
a reference already (such as from a previous FETCH) [perl
#72144].
o "splice" now calls set-magic (so changes made by "splice @ISA"
are respected by method calls) [perl #78400].
o In-memory files created by "open($fh, ">", \$buffer)" were not
calling FETCH/STORE at all [perl #43789] (5.12.2).
o utf8::is_utf8() now respects get-magic (like $1) (5.12.1).
o Non-commutative binary operators used to swap their operands if the
same tied scalar was used for both operands and returned a
different value for each FETCH. For instance, if $t returned 2 the
first time and 3 the second, then "$t/$t" would evaluate to 1.5.
This has been fixed [perl #87708].
o String "eval" now detects taintedness of overloaded or tied
arguments [perl #75716].
o String "eval" and regular expression matches against objects with
string overloading no longer cause memory corruption or crashes
[perl #77084].
o readline now honors "<>" overloading on tied arguments.
o "<expr>" always respects overloading now if the expression is
overloaded.
Because "<> as glob" was parsed differently from "<> as filehandle"
from 5.6 onwards, something like "<$foo[0]>" did not handle
overloading, even if $foo[0] was an overloaded object. This was
contrary to the documentation for overload, and meant that "<>"
could not be used as a general overloaded iterator operator.
o The fallback behaviour of overloading on binary operators was
asymmetric [perl #71286].
o Magic applied to variables in the main package no longer affects
other packages. See "Magic variables outside the main package"
above [perl #76138].
o 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].
o DESTROY methods of objects implementing ties are no longer able to
crash by accessing the tied variable through a weak reference [perl
#86328].
o Fixed a regression of kill() when a match variable is used for the
process ID to kill [perl #75812].
o $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.
o "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].
o "lc", "uc", "lcfirst", and "ucfirst" no longer return untainted
strings when the argument is tainted. This has been broken since
perl 5.8.9 [perl #87336].
The Debugger
o The Perl debugger now also works in taint mode [perl #76872].
o Subroutine redefinition works once more in the debugger [perl
#48332].
o When -d is used on the shebang ("#!") 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 the order in
which things happened to be arranged in memory [perl #71806].
o A possible memory leak when using caller() to set @DB::args has
been fixed (5.12.2).
o Perl no longer stomps on $DB::single, $DB::trace, and $DB::signal
if these variables already have values when $^P is assigned to
[perl #72422].
o "#line" directives in string evals were not properly updating the
arrays of lines of code ("@{"_< ..."}") 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].
Threads
o Perl no longer accidentally clones lexicals in scope within active
stack frames in the parent when creating a child thread [perl
#73086].
o Several memory leaks in cloning and freeing threaded Perl
interpreters have been fixed [perl #77352].
o 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 Windows and on systems
that have a "fchdir" function. On other systems, new threads
simply do not inherit directory handles from their parent threads
[perl #75154].
o The typeglob "*,", which holds the scalar variable $, (output field
separator), had the wrong reference count in child threads.
o [perl #78494] When pipes are shared between threads, the "close"
function (and any implicit close, such as on thread exit) no longer
blocks.
o Perl now does a timely cleanup of SVs that are cloned into a new
thread but then discovered to be orphaned (that is, their owners
are not cloned). This eliminates several "scalars leaked" warnings
when joining threads.
Scoping and Subroutines
o 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).
o "require" no longer causes "caller" to return the wrong file name
for the scope that called "require" and other scopes higher up that
had the same file name [perl #68712].
o "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].
o Match variables (like $1) no longer persist between calls to a sort
subroutine [perl #76026].
o Iterating with "foreach" over an array returned by an lvalue sub
now works [perl #23790].
o $@ is now localised during calls to "binmode" to prevent action at
a distance [perl #78844].
o Calling a closure prototype (what is passed to an attribute handler
for a closure) now results in a "Closure prototype called" error
message instead of a crash [perl #68560].
o Mentioning a read-only lexical variable from the enclosing scope in
a string "eval" no longer causes the variable to become writable
[perl #19135].
Signals
o Within signal handlers, $! is now implicitly localized.
o CHLD signals are no longer unblocked after a signal handler is
called if they were blocked before by "POSIX::sigprocmask" [perl
#82040].
o A signal handler called within a signal handler could cause leaks
or double-frees. Now fixed [perl #76248].
Miscellaneous Memory Leaks
o Several memory leaks when loading XS modules were fixed (5.12.2).
o substr(), pos(), keys(), and vec() 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.
o The postincrement and postdecrement operators, "++" and "--", used
to cause leaks when used on references. This has now been fixed.
o Nested "map" and "grep" blocks no longer leak memory when
processing large lists [perl #48004].
o "use VERSION" and "no VERSION" no longer leak memory [perl #78436]
[perl #69050].
o ".=" followed by "<>" or "readline" would leak memory if $/
contained characters beyond the octet range and the scalar assigned
to happened to be encoded as UTF8 internally [perl #72246].
o "eval 'BEGIN{die}'" no longer leaks memory on non-threaded builds.
Memory Corruption and Crashes
o glob() no longer crashes when %File::Glob:: is empty and
"CORE::GLOBAL::glob" isn't present [perl #75464] (5.12.2).
o readline() has been fixed when interrupted by signals so it no
longer returns the "same thing" as before or random memory.
o 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].
o The mechanism for freeing objects in globs used to leave dangling
pointers to freed SVs, meaning Perl users could see corrupted state
during destruction.
Perl now frees only 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.
o The interpreter no longer crashes when freeing deeply-nested arrays
of arrays. Hashes have not been fixed yet [perl #44225].
o Concatenating long strings under "use encoding" no longer causes
Perl to crash [perl #78674].
o Calling "->import" on a class lacking an import method could
corrupt the stack, resulting in strange behaviour. For instance,
push @a, "foo", $b = bar->import;
would assign "foo" to $b [perl #63790].
o The "recv" function could crash when called with the MSG_TRUNC flag
[perl #75082].
o "formline" no longer crashes when passed a tainted format picture.
It also taints $^A now if its arguments are tainted [perl #79138].
o 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).
o unpack() now handles scalar context correctly for %32H and %32u,
fixing a potential crash. split() would crash because the third
item on the stack wasn't the regular expression it expected.
"unpack("%2H", ...)" would return both the unpacked result and the
checksum on the stack, as would "unpack("%2u", ...)" [perl #73814]
(5.12.2).
Fixes to Various Perl Operators
o The "&", "|", and "^" bitwise operators no longer coerce read-only
arguments [perl #20661].
o Stringifying a scalar containing "-0.0" no longer has the effect of
turning false into true [perl #45133].
o Some numeric operators were converting integers to floating point,
resulting in loss of precision on 64-bit platforms [perl #77456].
o sprintf() was ignoring locales when called with constant arguments
[perl #78632].
o 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].
Bugs Relating to the C API
o The C-level "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).
o The "eval_sv" and "eval_pv" C functions now set $@ correctly when
there is a syntax error and no "G_KEEPERR" flag, and never set it
if the "G_KEEPERR" flag is present [perl #3719].
o 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].
o The "SvPVbyte" function available to XS modules now calls magic
before downgrading the SV, to avoid warnings about wide characters
[perl #72398].
o The ref types in the typemap for XS bindings now support magical
variables [perl #72684].
o "sv_catsv_flags" no longer calls "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.
o "my_strftime" no longer leaks memory. This fixes a memory leak in
"POSIX::strftime" [perl #73520].
o XSUB.h now correctly redefines fgets under PERL_IMPLICIT_SYS [perl
#55049] (5.12.1).
o XS code using fputc() or fputs() on Windows could cause an error
due to their arguments being swapped [perl #72704] (5.12.1).
o A possible segfault in the "T_PTROBJ" default typemap has been
fixed (5.12.2).
o A bug that could cause "Unknown error" messages when "call_sv(code,
G_EVAL)" is called from an XS destructor has been fixed (5.12.2).
Known Problems
This is a list of significant unresolved issues which are regressions
from earlier versions of Perl or which affect widely-used CPAN modules.
o "List::Util::first" misbehaves in the presence of a lexical $_
(typically introduced by "my $_" or implicitly by "given"). The
variable that gets set for each iteration is the package variable
$_, not the lexical $_.
A similar issue may occur in other modules that provide functions
which take a block as their first argument, like
foo { ... $_ ...} list
See also: <http://rt.perl.org/rt3/Public/Bug/Display.html?id=67694>;
o readline() returns an empty string instead of a cached previous
value when it is interrupted by a signal
o The changes in prototype handling break Switch. A patch has been
sent upstream and will hopefully appear on CPAN soon.
o The upgrade to ExtUtils-MakeMaker-6.57_05 has caused some tests in
the Module-Install distribution on CPAN to fail. (Specifically,
02_mymeta.t tests 5 and 21; 18_all_from.t tests 6 and 15;
19_authors.t tests 5, 13, 21, and 29; and
20_authors_with_special_characters.t tests 6, 15, and 23 in version
1.00 of that distribution now fail.)
o On VMS, "Time::HiRes" tests will fail due to a bug in the CRTL's
implementation of "setitimer": previous timer values would be
cleared if a timer expired but not if the timer was reset before
expiring. HP OpenVMS Engineering have corrected the problem and
will release a patch in due course (Quix case # QXCM1001115136).
o On VMS, there were a handful of "Module::Build" test failures we
didn't get to before the release; please watch CPAN for updates.
Errata
keys(), values(), and each() work on arrays
You can now use the keys(), values(), and each() builtins on arrays;
previously you could use them only on hashes. See perlfunc for
details. This is actually a change introduced in perl 5.12.0, but it
was missed from that release's perl5120delta.
split() and @_
split() no longer modifies @_ when called in scalar or void context.
In void context it now produces a "Useless use of split" warning. This
was also a perl 5.12.0 change that missed the perldelta.
Obituary
Randy Kobes, creator of http://kobesearch.cpan.org/ and
contributor/maintainer to several core Perl toolchain modules, passed
away on September 18, 2010 after a battle with lung cancer. The
community was richer for his involvement. He will be missed.
Acknowledgements
Perl 5.14.0 represents one year of development since Perl 5.12.0 and
contains nearly 550,000 lines of changes across nearly 3,000 files from
150 authors and committers.
Perl continues to flourish into its third decade thanks to a vibrant
community of users and developers. The following people are known to
have contributed the improvements that became Perl 5.14.0:
Aaron Crane, Abhijit Menon-Sen, Abigail, var Arnfjoer` Bjarmason,
Alastair Douglas, Alexander Alekseev, Alexander Hartmaier, Alexandr
Ciornii, Alex Davies, Alex Vandiver, Ali Polatel, Allen Smith, Andreas
Koenig, Andrew Rodland, Andy Armstrong, Andy Dougherty, Aristotle
Pagaltzis, Arkturuz, Arvan, A. Sinan Unur, Ben Morrow, Bo Lindbergh,
Boris Ratner, Brad Gilbert, Bram, brian d foy, Brian Phillips, Casey
West, Charles Bailey, Chas. Owens, Chip Salzenberg, Chris 'BinGOs'
Williams, chromatic, Craig A. Berry, Curtis Jewell, Dagfinn Ilmari
Mannsaaker, Dan Dascalescu, Dave Rolsky, David Caldwell, David
Cantrell, David Golden, David Leadbeater, David Mitchell, David
Wheeler, Eric Brine, Father Chrysostomos, Fingle Nark, Florian Ragwitz,
Frank Wiegand, Franz Fasching, Gene Sullivan, George Greer, Gerard
Goossen, Gisle Aas, Goro Fuji, Grant McLean, gregor herrmann, H.Merijn
Brand, Hongwen Qiu, Hugo van der Sanden, Ian Goodacre, James E Keenan,
James Mastros, Jan Dubois, Jay Hannah, Jerry D. Hedden, Jesse Vincent,
Jim Cromie, Jirka HruXka, John Peacock, Joshua ben Jore, Joshua
Pritikin, Karl Williamson, Kevin Ryde, kmx, Lars DXXXXXX XXX, Larwan
Berke, Leon Brocard, Leon Timmermans, Lubomir Rintel, Lukas Mai, Maik
Hentsche, Marty Pauley, Marvin Humphrey, Matt Johnson, Matt S Trout,
Max Maischein, Michael Breen, Michael Fig, Michael G Schwern, Michael
Parker, Michael Stevens, Michael Witten, Mike Kelly, Moritz Lenz,
Nicholas Clark, Nick Cleaton, Nick Johnston, Nicolas Kaiser, Niko Tyni,
Noirin Shirley, Nuno Carvalho, Paul Evans, Paul Green, Paul Johnson,
Paul Marquess, Peter J. Holzer, Peter John Acklam, Peter Martini,
Philippe Bruhat (BooK), Piotr Fusik, Rafael Garcia-Suarez, Rainer
Tammer, Reini Urban, Renee Baecker, Ricardo Signes, Richard Moehn,
Richard Soderberg, Rob Hoelz, Robin Barker, Ruslan Zakirov, Salvador
Fandin~o, Salvador Ortiz Garcia, Shlomi Fish, Sinan Unur, Sisyphus,
Slaven Rezic, Steffen Mueller, Steve Hay, Steven Schubiger, Steve
Peters, Sullivan Beck, Tatsuhiko Miyagawa, Tim Bunce, Todd Rinaldo, Tom
Christiansen, Tom Hukins, Tony Cook, Tye McQueen, Vadim Konovalov,
Vernon Lyon, Vincent Pit, Walt Mankowski, Wolfram Humann, Yves Orton,
Zefram, and Zsban Ambrus.
This is woefully incomplete as it's automatically generated from
version control history. In particular, it doesn't include the names
of the (very much appreciated) contributors who reported issues in
previous versions of Perl that helped make Perl 5.14.0 better. For a
more complete list of all of Perl's historical contributors, please see
the "AUTHORS" file in the Perl 5.14.0 distribution.
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.
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 http://rt.perl.org/perlbug/ . There may also be
information at http://www.perl.org/ , the Perl Home Page.
If you believe you have an unreported bug, please run the 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 AT 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 AT perl.org. This points to a closed
subscription unarchived mailing list, which includes all the core
committers, who are 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 use this address for security issues in the Perl
core only, not for modules independently distributed on CPAN.
SEE ALSO
The Changes file for an explanation of how to view exhaustive details
on what changed.
The INSTALL file for how to build Perl.
The README file for general stuff.
The Artistic and Copying files for copyright information.
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