perl5180delta - what is new for perl v5.18.0
This document describes differences between the v5.16.0 release and the v5.18.0 release.
If you are upgrading from an earlier release such as v5.14.0, first read perl5160delta, which describes differences between v5.14.0 and v5.16.0.
Newly-added experimental features will now require this incantation:
no warnings "experimental::feature_name"; use feature "feature_name"; # would warn without the prev line
There is a new warnings category, called "experimental", containing warnings that the feature pragma emits when enabling experimental features.
Newly-added experimental features will also be given special warning IDs, which consist of "experimental::" followed by the name of the feature. (The plan is to extend this mechanism eventually to all warnings, to allow them to be enabled or disabled individually, and not just by category.)
By saying
no warnings "experimental::feature_name";
you are taking responsibility for any breakage that future changes to, or removal of, the feature may cause.
Since some features (like ~~ or my $_) now emit experimental warnings, and you may want to disable them in code that is also run on perls that do not recognize these warning categories, consider using the if pragma like this:
no if $] >= 5.018, warnings => "experimental::feature_name";
Existing experimental features may begin emitting these warnings, too. Please consult perlexperiment for information on which features are considered experimental.
Changes to the implementation of hashes in perl v5.18.0 will be one of the most visible changes to the behavior of existing code.
By default, two distinct hash variables with identical keys and values may now provide their contents in a different order where it was previously identical.
When encountering these changes, the key to cleaning up from them is to accept that hashes are unordered collections and to act accordingly.
The seed used by Perl's hash function is now random. This means that the order which keys/values will be returned from functions like keys(), values(), and each() will differ from run to run.
This change was introduced to make Perl's hashes more robust to algorithmic complexity attacks, and also because we discovered that it exposes hash ordering dependency bugs and makes them easier to track down.
Toolchain maintainers might want to invest in additional infrastructure to test for things like this. Running tests several times in a row and then comparing results will make it easier to spot hash order dependencies in code. Authors are strongly encouraged not to expose the key order of Perl's hashes to insecure audiences.
Further, every hash has its own iteration order, which should make it much more difficult to determine what the current hash seed is.
Perl v5.18 includes support for multiple hash functions, and changed the default (to ONE_AT_A_TIME_HARD), you can choose a different algorithm by defining a symbol at compile time. For a current list, consult the INSTALL document. Note that as of Perl v5.18 we can only recommend use of the default or SIPHASH. All the others are known to have security issues and are for research purposes only.
PERL_HASH_SEED no longer accepts an integer as a parameter; instead the value is expected to be a binary value encoded in a hex string, such as "0xf5867c55039dc724". This is to make the infrastructure support hash seeds of arbitrary lengths, which might exceed that of an integer. (SipHash uses a 16 byte seed.)
The PERL_PERTURB_KEYS environment variable allows one to control the level of randomization applied to keys and friends.
When PERL_PERTURB_KEYS is 0, perl will not randomize the key order at all. The chance that keys changes due to an insert will be the same as in previous perls, basically only when the bucket size is changed.
When PERL_PERTURB_KEYS is 1, perl will randomize keys in a non-repeatable way. The chance that keys changes due to an insert will be very high. This is the most secure and default mode.
When PERL_PERTURB_KEYS is 2, perl will randomize keys in a repeatable way. Repeated runs of the same program should produce the same output every time.
PERL_HASH_SEED implies a non-default PERL_PERTURB_KEYS setting. Setting PERL_HASH_SEED=0 (exactly one 0) implies PERL_PERTURB_KEYS=0 (hash key randomization disabled); setting PERL_HASH_SEED to any other value implies PERL_PERTURB_KEYS=2 (deterministic and repeatable hash key randomization). Specifying PERL_PERTURB_KEYS explicitly to a different level overrides this behavior.
Hash::Util::hash_seed() now returns a string instead of an integer. This is to make the infrastructure support hash seeds of arbitrary lengths which might exceed that of an integer. (SipHash uses a 16 byte seed.)
The environment variable PERL_HASH_SEED_DEBUG now makes perl show both the hash function perl was built with, and the seed, in hex, in use for that process. Code parsing this output, should it exist, must change to accommodate the new format. Example of the new format:
$ PERL_HASH_SEED_DEBUG=1 ./perl -e1 HASH_FUNCTION = MURMUR3 HASH_SEED = 0x1476bb9f
Perl now supports Unicode 6.2. A list of changes from Unicode 6.1 is at http://www.unicode.org/versions/Unicode6.2.0.
It is possible to define your own names for characters for use in \N{...}, charnames::vianame(), etc. These names can now be comprised of characters from the whole Unicode range. This allows for names to be in your native language, and not just English. Certain restrictions apply to the characters that may be used (you can't define a name that has punctuation in it, for example). See "CUSTOM ALIASES" in charnames.
The following new DTrace probes have been added:
op-entryloading-fileloaded-file${^LAST_FH}
This new variable provides access to the filehandle that was last read. This is the handle used by $. and by tell and eof without arguments.
This is an experimental feature to allow matching against the union, intersection, etc., of sets of code points, similar to Unicode::Regex::Set. It can also be used to extend /x processing to [bracketed] character classes, and as a replacement of user-defined properties, allowing more complex expressions than they do. See "Extended Bracketed Character Classes" in perlrecharclass.
This new feature is still considered experimental. To enable it:
use 5.018; no warnings "experimental::lexical_subs"; use feature "lexical_subs";
You can now declare subroutines with state sub foo, my sub foo, and our sub foo. (state sub requires that the "state" feature be enabled, unless you write it as CORE::state sub foo.)
state sub creates a subroutine visible within the lexical scope in which it is declared. The subroutine is shared between calls to the outer sub.
my sub declares a lexical subroutine that is created each time the enclosing block is entered. state sub is generally slightly faster than my sub.
our sub declares a lexical alias to the package subroutine of the same name.
For more information, see "Lexical Subroutines" in perlsub.
The loop controls next, last and redo, and the special dump operator, now allow arbitrary expressions to be used to compute labels at run time. Previously, any argument that was not a constant was treated as the empty string.
Several more built-in functions have been added as subroutines to the CORE:: namespace - namely, those non-overridable keywords that can be implemented without custom parsers: defined, delete, exists, glob, pos, prototype, scalar, split, study, and undef.
As some of these have prototypes, prototype('CORE::...') has been changed to not make a distinction between overridable and non-overridable keywords. This is to make prototype('CORE::pos') consistent with prototype(&CORE::pos).
kill with negative signal names
kill has always allowed a negative signal number, which kills the process group instead of a single process. It has also allowed signal names. But it did not behave consistently, because negative signal names were treated as 0. Now negative signals names like -INT are supported and treated the same way as -2 [perl #112990].
Some of the changes in the hash overhaul were made to enhance security. Please read that section.
Storable security warning in documentation
The documentation for Storable now includes a section which warns readers of the danger of accepting Storable documents from untrusted sources. The short version is that deserializing certain types of data can lead to loading modules and other code execution. This is documented behavior and wanted behavior, but this opens an attack vector for malicious entities.
Locale::Maketext allowed code injection via a malicious templateIf users could provide a translation string to Locale::Maketext, this could be used to invoke arbitrary Perl subroutines available in the current process.
This has been fixed, but it is still possible to invoke any method provided by Locale::Maketext itself or a subclass that you are using. One of these methods in turn will invoke the Perl core's sprintf subroutine.
In summary, allowing users to provide translation strings without auditing them is a bad idea.
This vulnerability is documented in CVE-2012-6329.
Poorly written perl code that allows an attacker to specify the count to perl's x string repeat operator can already cause a memory exhaustion denial-of-service attack. A flaw in versions of perl before v5.15.5 can escalate that into a heap buffer overrun; coupled with versions of glibc before 2.16, it possibly allows the execution of arbitrary code.
The flaw addressed to this commit has been assigned identifier CVE-2012-5195 and was researched by Tim Brown.
Some of the changes in the hash overhaul are not fully compatible with previous versions of perl. Please read that section.
\N{...} is now a syntax errorPreviously, it warned, and the Unicode REPLACEMENT CHARACTER was substituted. Unicode now recommends that this situation be a syntax error. Also, the previous behavior led to some confusing warnings and behaviors, and since the REPLACEMENT CHARACTER has no use other than as a stand-in for some unknown character, any code that has this problem is buggy.
\N{} character name aliases are now errors.
Since v5.12.0, it has been deprecated to use certain characters in user-defined \N{...} character names. These now cause a syntax error. For example, it is now an error to begin a name with a digit, such as in
my $undraftable = "\N{4F}"; # Syntax error!
or to have commas anywhere in the name. See "CUSTOM ALIASES" in charnames.
\N{BELL} now refers to U+1F514 instead of U+0007Unicode 6.0 reused the name "BELL" for a different code point than it traditionally had meant. Since Perl v5.14, use of this name still referred to U+0007, but would raise a deprecation warning. Now, "BELL" refers to U+1F514, and the name for U+0007 is "ALERT". All the functions in charnames have been correspondingly updated.
Unicode has now withdrawn their previous recommendation for regular expressions to automatically handle cases where a single character can match multiple characters case-insensitively, for example, the letter LATIN SMALL LETTER SHARP S and the sequence ss. This is because it turns out to be impracticable to do this correctly in all circumstances. Because Perl has tried to do this as best it can, it will continue to do so. (We are considering an option to turn it off.) However, a new restriction is being added on such matches when they occur in [bracketed] character classes. People were specifying things such as /[\0-\xff]/i, and being surprised that it matches the two character sequence ss (since LATIN SMALL LETTER SHARP S occurs in this range). This behavior is also inconsistent with using a property instead of a range: \p{Block=Latin1} also includes LATIN SMALL LETTER SHARP S, but /[\p{Block=Latin1}]/i does not match ss. The new rule is that for there to be a multi-character case-insensitive match within a bracketed character class, the character must be explicitly listed, and not as an end point of a range. This more closely obeys the Principle of Least Astonishment. See "Bracketed Character Classes" in perlrecharclass. Note that a bug [perl #89774], now fixed as part of this change, prevented the previous behavior from working fully.
Due to an oversight, single character variable names in v5.16 were completely unrestricted. This opened the door to several kinds of insanity. As of v5.18, these now follow the rules of other identifiers, in addition to accepting characters that match the \p{POSIX_Punct} property.
There is no longer any difference in the parsing of identifiers specified by using braces versus without braces. For instance, perl used to allow ${foo:bar} (with a single colon) but not $foo:bar. Now that both are handled by a single code path, they are both treated the same way: both are forbidden. Note that this change is about the range of permissible literal identifiers, not other expressions.
No one could recall why \s didn't match \cK, the vertical tab. Now it does. Given the extreme rarity of that character, very little breakage is expected. That said, here's what it means:
\s in a regex now matches a vertical tab in all circumstances.
Literal vertical tabs in a regex literal are ignored when the /x modifier is used.
Leading vertical tabs, alone or mixed with other whitespace, are now ignored when interpreting a string as a number. For example:
$dec = " \cK \t 123"; $hex = " \cK \t 0xF"; say 0 + $dec; # was 0 with warning, now 123 say int $dec; # was 0, now 123 say oct $hex; # was 0, now 15
/(?{})/ and /(??{})/ have been heavily reworkedThe implementation of this feature has been almost completely rewritten. Although its main intent is to fix bugs, some behaviors, especially related to the scope of lexical variables, will have changed. This is described more fully in the "Selected Bug Fixes" section.
It is no longer possible to abuse the way the parser parses s///e like this:
%_=(_,"Just another ");
$_="Perl hacker,\n";
s//_}->{_/e;print
given now aliases the global $_
Instead of assigning to an implicit lexical $_, given now makes the global $_ an alias for its argument, just like foreach. However, it still uses lexical $_ if there is lexical $_ in scope (again, just like foreach) [perl #114020].
Smart match, added in v5.10.0 and significantly revised in v5.10.1, has been a regular point of complaint. Although there are a number of ways in which it is useful, it has also proven problematic and confusing for both users and implementors of Perl. There have been a number of proposals on how to best address the problem. It is clear that smartmatch is almost certainly either going to change or go away in the future. Relying on its current behavior is not recommended.
Warnings will now be issued when the parser sees ~~, given, or when. To disable these warnings, you can add this line to the appropriate scope:
no if $] >= 5.018, warnings => "experimental::smartmatch";
Consider, though, replacing the use of these features, as they may change behavior again before becoming stable.
$_ is now experimentalSince it was introduced in Perl v5.10, it has caused much confusion with no obvious solution:
$_. use List::Util 'first'; my $_; first { $_ == 1 } @list does not work as one would expect.my $_ declaration earlier in the same file can cause confusing closure warnings.$_, so it is not really private after all.$_, unless they are written in XS.$_ declared, not in the calling subroutine, but in an outer scope, iff that subroutine happened not to mention $_ or use any operators that default to $_.
It is our hope that lexical $_ can be rehabilitated, but this may cause changes in its behavior. Please use it with caution until it becomes stable.
$/ = \N now reads N characters, not N bytes
Previously, when reading from a stream with I/O layers such as encoding, the readline() function, otherwise known as the <> operator, would read N bytes from the top-most layer. [perl #79960]
Now, N characters are read instead.
There is no change in behaviour when reading from streams with no extra layers, since bytes map exactly to characters.
glob is now passed one argument
glob overrides used to be passed a magical undocumented second argument that identified the caller. Nothing on CPAN was using this, and it got in the way of a bug fix, so it was removed. If you really need to identify the caller, see Devel::Callsite on CPAN.
The body of a here document inside a quote-like operator now always begins on the line after the "<<foo" marker. Previously, it was documented to begin on the line following the containing quote-like operator, but that was only sometimes the case [perl #114040].
You may no longer write something like:
m/a/and 1
Instead you must write
m/a/ and 1
with whitespace separating the operator from the closing delimiter of the regular expression. Not having whitespace has resulted in a deprecation warning since Perl v5.14.0.
qw lists used to fool the parser into thinking they were always surrounded by parentheses. This permitted some surprising constructions such as foreach $x qw(a b c) {...}, which should really be written foreach $x (qw(a b c)) {...}. These would sometimes get the lexer into the wrong state, so they didn't fully work, and the similar foreach qw(a b c) {...} that one might expect to be permitted never worked at all.
This side effect of qw has now been abolished. It has been deprecated since Perl v5.13.11. It is now necessary to use real parentheses everywhere that the grammar calls for them.
Turning on any lexical warnings used first to disable all default warnings if lexical warnings were not already enabled:
$*; # deprecation warning use warnings "void"; $#; # void warning; no deprecation warning
Now, the debugging, deprecated, glob, inplace and malloc warnings categories are left on when turning on lexical warnings (unless they are turned off by no warnings, of course).
This may cause deprecation warnings to occur in code that used to be free of warnings.
Those are the only categories consisting only of default warnings. Default warnings in other categories are still disabled by use warnings "category", as we do not yet have the infrastructure for controlling individual warnings.
state sub and our sub
Due to an accident of history, state sub and our sub were equivalent to a plain sub, so one could even create an anonymous sub with our sub { ... }. These are now disallowed outside of the "lexical_subs" feature. Under the "lexical_subs" feature they have new meanings described in "Lexical Subroutines" in perlsub.
A value stored in an environment variable has always been stringified when inherited by child processes.
In this release, when assigning to %ENV, values are immediately stringified, and converted to be only a byte string.
First, it is forced to be only a string. Then if the string is utf8 and the equivalent of utf8::downgrade() works, that result is used; otherwise, the equivalent of utf8::encode() is used, and a warning is issued about wide characters ("Diagnostics").
require dies for unreadable files
When require encounters an unreadable file, it now dies. It used to ignore the file and continue searching the directories in @INC [perl #113422].
gv_fetchmeth_* and SUPER
The various gv_fetchmeth_* XS functions used to treat a package whose named ended with ::SUPER specially. A method lookup on the Foo::SUPER package would be treated as a SUPER method lookup on the Foo package. This is no longer the case. To do a SUPER lookup, pass the Foo stash and the GV_SUPER flag.
split's first argument is more consistently interpreted
After some changes earlier in v5.17, split's behavior has been simplified: if the PATTERN argument evaluates to a string containing one space, it is treated the way that a literal string containing one space once was.
The following modules will be removed from the core distribution in a future release, and will at that time need to be installed from CPAN. Distributions on CPAN which require these modules will need to list them as prerequisites.
The core versions of these modules will now issue "deprecated"-category warnings to alert you to this fact. To silence these deprecation warnings, install the modules in question from CPAN.
Note that these are (with rare exceptions) fine modules that you are encouraged to continue to use. Their disinclusion from core primarily hinges on their necessity to bootstrapping a fully functional, CPAN-capable Perl installation, not usually on concerns over their design.
The use of this pragma is now strongly discouraged. It conflates the encoding of source text with the encoding of I/O data, reinterprets escape sequences in source text (a questionable choice), and introduces the UTF-8 bug to all runtime handling of character strings. It is broken as designed and beyond repair.
For using non-ASCII literal characters in source text, please refer to utf8. For dealing with textual I/O data, please refer to Encode and open.
CPANPLUS::* modulesThe following utilities will be removed from the core distribution in a future release as their associated modules have been deprecated. They will remain available with the applicable CPAN distribution.
cpanp-run-perl
These items are part of the CPANPLUS distribution.
This item is part of the Pod::LaTeX distribution.
This interpreter-global variable used to track the total number of Perl objects in the interpreter. It is no longer maintained and will be removed altogether in Perl v5.20.
/x
When a regular expression pattern is compiled with /x, Perl treats 6 characters as white space to ignore, such as SPACE and TAB. However, Unicode recommends 11 characters be treated thusly. We will conform with this in a future Perl version. In the meantime, use of any of the missing characters will raise a deprecation warning, unless turned off. The five characters are:
U+0085 NEXT LINE U+200E LEFT-TO-RIGHT MARK U+200F RIGHT-TO-LEFT MARK U+2028 LINE SEPARATOR U+2029 PARAGRAPH SEPARATOR
A user-defined character name with trailing or multiple spaces in a row is likely a typo. This now generates a warning when defined, on the assumption that uses of it will be unlikely to include the excess whitespace.
All the functions used to classify characters will be removed from a future version of Perl, and should not be used. With participating C compilers (e.g., gcc), compiling any file that uses any of these will generate a warning. These were not intended for public use; there are equivalent, faster, macros for most of them.
See "Character classes" in perlapi. The complete list is:
is_uni_alnum, is_uni_alnumc, is_uni_alnumc_lc, is_uni_alnum_lc, is_uni_alpha, is_uni_alpha_lc, is_uni_ascii, is_uni_ascii_lc, is_uni_blank, is_uni_blank_lc, is_uni_cntrl, is_uni_cntrl_lc, is_uni_digit, is_uni_digit_lc, is_uni_graph, is_uni_graph_lc, is_uni_idfirst, is_uni_idfirst_lc, is_uni_lower, is_uni_lower_lc, is_uni_print, is_uni_print_lc, is_uni_punct, is_uni_punct_lc, is_uni_space, is_uni_space_lc, is_uni_upper, is_uni_upper_lc, is_uni_xdigit, is_uni_xdigit_lc, is_utf8_alnum, is_utf8_alnumc, is_utf8_alpha, is_utf8_ascii, is_utf8_blank, is_utf8_char, is_utf8_cntrl, is_utf8_digit, is_utf8_graph, is_utf8_idcont, is_utf8_idfirst, is_utf8_lower, is_utf8_mark, is_utf8_perl_space, is_utf8_perl_word, is_utf8_posix_digit, is_utf8_print, is_utf8_punct, is_utf8_space, is_utf8_upper, is_utf8_xdigit, is_utf8_xidcont, is_utf8_xidfirst.
In addition these three functions that have never worked properly are deprecated: to_uni_lower_lc, to_uni_title_lc, and to_uni_upper_lc.
There are three pairs of characters that Perl recognizes as metacharacters in regular expression patterns: {}, [], and (). These can be used as well to delimit patterns, as in:
m{foo}
s(foo)(bar)
Since they are metacharacters, they have special meaning to regular expression patterns, and it turns out that you can't turn off that special meaning by the normal means of preceding them with a backslash, if you use them, paired, within a pattern delimited by them. For example, in
m{foo\{1,3\}}
the backslashes do not change the behavior, and this matches "f o""o".
Usages like this, where they are interpreted as metacharacters, are exceedingly rare; we think there are none, for example, in all of CPAN. Hence, this deprecation should affect very little code. It does give notice, however, that any such code needs to change, which will in turn allow us to change the behavior in future Perl versions so that the backslashes do have an effect, and without fear that we are silently breaking any existing code.
(? and (* in regular expressions
A deprecation warning is now raised if the ( and ? are separated by white space or comments in (?...) regular expression constructs. Similarly, if the ( and * are separated in (*VERB...) constructs.
In theory, you can currently build perl without PerlIO. Instead, you'd use a wrapper around stdio or sfio. In practice, this isn't very useful. It's not well tested, and without any support for IO layers or (thus) Unicode, it's not much of a perl. Building without PerlIO will most likely be removed in the next version of perl.
PerlIO supports a stdio layer if stdio use is desired. Similarly a sfio layer could be produced in the future, if needed.
Both Windows CE and z/OS have been historically under-maintained, and are currently neither successfully building nor regularly being smoke tested. Efforts are underway to change this situation, but it should not be taken for granted that the platforms are safe and supported. If they do not become buildable and regularly smoked, support for them may be actively removed in future releases. If you have an interest in these platforms and you can lend your time, expertise, or hardware to help support these platforms, please let the perl development effort know by emailing perl5-porters@perl.org.
Some platforms that appear otherwise entirely dead are also on the short list for removal between now and v5.20.0:
We also think it likely that current versions of Perl will no longer build AmigaOS, DJGPP, NetWare (natively), OS/2 and Plan 9. If you are using Perl on such a platform and have an interest in ensuring Perl's future on them, please contact us.
We believe that Perl has long been unable to build on mixed endian architectures (such as PDP-11s), and intend to remove any remaining support code. Similarly, code supporting the long unmaintained GNU dld will be removed soon if no-one makes themselves known as an active user.
Perl has supported the idiom of swapping $< and $> (and likewise $( and $)) to temporarily drop permissions since 5.0, like this:
($<, $>) = ($>, $<);
However, this idiom modifies the real user/group id, which can have undesirable side-effects, is no longer useful on any platform perl supports and complicates the implementation of these variables and list assignment in general.
As an alternative, assignment only to $> is recommended:
local $> = $<;
See also: Setuid Demystified.
microperl, long broken and of unclear present purpose, will be removed."\Q" semantics in double-quotish strings when combined with other escapes.
There are several bugs and inconsistencies involving combinations of \Q and escapes like \x, \L, etc., within a \Q...\E pair. These need to be fixed, and doing so will necessarily change current behavior. The changes have not yet been settled.
$x, where x stands for any actual (non-printing) C0 control character will be disallowed in a future Perl version. Use ${x} instead (where again x stands for a control character), or better, $^A , where ^ is a caret (CIRCUMFLEX ACCENT), and A stands for any of the characters listed at the end of "OPERATOR DIFFERENCES" in perlebcdic.my($x, $y)) are now optimised down to a single op and are hence faster than before.NO_TAINT_SUPPORT was added that, if set, disables Perl's taint support altogether. Using the -T or -t command line flags will cause a fatal error. Beware that both core tests as well as many a CPAN distribution's tests will fail with this change. On the upside, it provides a small performance benefit due to reduced branching.Do not enable this unless you know exactly what you are getting yourself into.
pack with constant arguments is now constant folded in most cases [perl #113470].\X, the Unicode "extended grapheme cluster." The gain for it is about 35% - 40%. Bracketed character classes, e.g., [0-9\x{100}] containing code points above 255 are also now faster.scalar(%hash), %hash ? ... : ..., and sub { %hash || ... }.x repetition operator is now folded to a single constant at compile time if called in scalar context with constant operands and no parentheses around the left operand.perl -V output including information only known to the perl binary and not available via Config.For a complete list of updates, run:
$ corelist --diff 5.16.0 5.18.0
You can substitute your favorite version in place of 5.16.0, too.
Work around an edge case on Linux with Busybox's unzip.
ptar now supports the -T option as well as dashless options [rt.cpan.org #75473], [rt.cpan.org #75475].
Auto-encode filenames marked as UTF-8 [rt.cpan.org #75474].
Don't use tell on IO::Zlib handles [rt.cpan.org #64339].
Don't try to chown on symlinks.
autodie now plays nicely with the 'open' pragma.
The stashoff method of COPs has been added. This provides access to an internal field added in perl 5.16 under threaded builds [perl #113034].
B::COP::stashpv now supports UTF-8 package names and embedded NULs.
All CVf_* and GVf_* and more SV-related flag values are now provided as constants in the B:: namespace and available for export. The default export list has not changed.
This makes the module work with the new pad API.
The -nobanner option has been fixed, and formats can now be dumped. When passed a sub name to dump, it will check also to see whether it is the name of a format. If a sub and a format share the same name, it will dump both.
This adds support for the new OpMAYBE_TRUEBOOL and OPpTRUEBOOL flags.
This adds support (experimentally) for B::PADLIST, which was added in Perl 5.17.4.
Avoid warning when run under perl -w.
It now deparses loop controls with the correct precedence, and multiple statements in a format line are also now deparsed correctly.
This release suppresses trailing semicolons in formats.
This release adds stub deparsing for lexical subroutines.
It no longer dies when deparsing sort without arguments. It now correctly omits the comma for system $prog @args and exec $prog @args.
The overrides for hex and oct have been rewritten, eliminating several problems, and making one incompatible change:
use bigint or use bigrat was compiled later would take precedence over the other, causing hex and oct not to respect the other pragma when in scope.hex and oct anywhere else in the program to evaluate their arguments in list context and prevent them from inferring $_ when called without arguments.oct("1234") return 1234 (for any number not beginning with 0) anywhere in the program. Now "1234" is translated from octal to decimal, whether within the pragma's scope or not.hex and oct now respect any existing overrides that were in place before the new overrides were installed, falling back to them outside of the scope of use bignum.use bignum "hex", use bignum "oct" and similar invocations for bigint and bigrat now export a hex or oct function, instead of providing a global override.
Carp is no longer confused when caller returns undef for a package that has been deleted.
The longmess() and shortmess() functions are now documented.
Unrecognized HTML escape sequences are now handled better, problematic trailing newlines are no longer inserted after <form> tags by startform() or start_form(), and bogus "Insecure Dependency" warnings appearing with some versions of perl are now worked around.
The constructor now respects overridden accessor methods [perl #29230].
The misuse of Perl's "magic" API has been fixed.
Upgrade bundled zlib to version 1.2.7.
Fix build failures on Irix, Solaris, and Win32, and also when building as C++ [rt.cpan.org #69985], [rt.cpan.org #77030], [rt.cpan.org #75222].
The misuse of Perl's "magic" API has been fixed.
compress(), uncompress(), memGzip() and memGunzip() have been speeded up by making parameter validation more efficient.
Treat undef requirements to from_string_hash as 0 (with a warning).
Added requirements_for_module method.
Allow adding blib/script to PATH.
Save the history between invocations of the shell.
Handle multiple makemakerargs and makeflags arguments better.
This resolves issues with the SQLite source engine.
It has been optimized to only build a seen-scalar hash as necessary, thereby speeding up serialization drastically.
Additional tests were added in order to improve statement, branch, condition and subroutine coverage. On the basis of the coverage analysis, some of the internals of Dumper.pm were refactored. Almost all methods are now documented.
The main Perl module no longer uses the "@_" construct.
This fixes compilation with C++ compilers and makes the module work with the new pad API.
Fix Digest::Perl::MD5 OO fallback [rt.cpan.org #66634].
This fixes a double-free bug, which might have caused vulnerabilities in some cases.
This is due to a minor code change in the XS for the VMS implementation.
This fixes warnings about using CODE sections without an OUTPUT section.
The Mac alias x-mac-ce has been added, and various bugs have been fixed in Encode::Unicode, Encode::UTF7 and Encode::GSM0338.
Its SPLICE implementation no longer misbehaves in list context.
Manifest files are now correctly embedded for those versions of VC++ which make use of them. [perl #111782, #111798].
A list of symbols to export can now be passed to link() when on Windows, as on other OSes [perl #115100].
The generated C code now avoids unnecessarily incrementing PL_amagic_generation on Perl versions where it's done automatically (or on current Perl where the variable no longer exists).
This avoids a bogus warning for initialised XSUB non-parameters [perl #112776].
copy() no longer zeros files when copying into the same directory, and also now fails (as it has long been documented to do) when attempting to copy a file over itself.
The internal cache of file names that it keeps for each caller is now freed when that caller is freed. This means use File::DosGlob 'glob'; eval 'scalar <*>' no longer leaks memory.
Added the 'file_default' option for URLs that do not have a file component.
Use File::HomeDir when available, and provide PERL5_CPANPLUS_HOME to override the autodetection.
Always re-fetch CHECKSUMS if fetchdir is set.
This fixes inconsistent unixy path handling on VMS.
Individual files may now appear in list of directories to be searched [perl #59750].
File::Glob has had exactly the same fix as File::DosGlob. Since it is what Perl's own glob operator itself uses (except on VMS), this means eval 'scalar <*>' no longer leaks.
A space-separated list of patterns return long lists of results no longer results in memory corruption or crashes. This bug was introduced in Perl 5.16.0. [perl #114984]
abs2rel could produce incorrect results when given two relative paths or the root directory twice [perl #111510].
File::stat ignores the filetest pragma, and warns when used in combination therewith. But it was not warning for -r. This has been fixed [perl #111640].
-p now works, and does not return false for pipes [perl #111638].
Previously File::stat's overloaded -x and -X operators did not give the correct results for directories or executable files when running as root. They had been treating executable permissions for root just like for any other user, performing group membership tests etc for files not owned by root. They now follow the correct Unix behaviour - for a directory they are always true, and for a file if any of the three execute permission bits are set then they report that root can execute the file. Perl's builtin -x and -X operators have always been correct.
Fixes various bugs involving directory removal. Defers unlinking tempfiles if the initial unlink fails, which fixes problems on NFS.
The undocumented optional fifth parameter to TIEHASH has been removed. This was intended to provide control of the callback used by gdbm* functions in case of fatal errors (such as filesystem problems), but did not work (and could never have worked). No code on CPAN even attempted to use it. The callback is now always the previous default, croak. Problems on some platforms with how the C croak function is called have also been resolved.
hash_unlocked and hashref_unlocked now returns true if the hash is unlocked, instead of always returning false [perl #112126].
hash_unlocked, hashref_unlocked, lock_hash_recurse and unlock_hash_recurse are now exportable [perl #112126].
Two new functions, hash_locked and hashref_locked, have been added. Oddly enough, these two functions were already exported, even though they did not exist [perl #112126].
Add SSL verification features [github #6], [github #9].
Include the final URL in the response hashref.
Add local_address option.
This improves SSL support.
sync() can now be called on read-only file handles [perl #64772].
IO::Socket tries harder to cache or otherwise fetch socket information.
Use POSIX::_exit instead of exit in run_forked [rt.cpan.org #76901].
The open3() function no longer uses POSIX::close() to close file descriptors since that breaks the ref-counting of file descriptors done by PerlIO in cases where the file descriptors are shared by PerlIO streams, leading to attempts to close the file descriptors a second time when any such PerlIO streams are closed later on.
It includes some new codes.
Fix the MERGE cache option.
Fixed bug where modules without $VERSION might have a version of '0' listed in 'provides' metadata, which will be rejected by PAUSE.
Fixed bug in PodParser to allow numerals in module names.
Fixed bug where giving arguments twice led to them becoming arrays, resulting in install paths like ARRAY(0xdeadbeef)/lib/Foo.pm.
A minor bug fix allows markup to be used around the leading "Name" in a POD "abstract" line, and some documentation improvements have been made.
Version information is now stored as a delta, which greatly reduces the size of the CoreList.pm file.
This restores compatibility with older versions of perl and cleans up the corelist data for various modules.
Fix use of requires on perls installed to a path with spaces.
Various enhancements include the new use of Module::Metadata.
The creation of a Module::Metadata object for a typical module file has been sped up by about 40%, and some spurious warnings about $VERSIONs have been suppressed.
Amongst other changes, triggers are now allowed on events, which gives a powerful way to modify behaviour.
This fixes some test failures on Windows.
Reflect the removal of the boolkeys opcode and the addition of the clonecv, introcv and padcv opcodes.
no overload now warns for invalid arguments, just like use overload.
This is the module implementing the ":encoding(...)" I/O layer. It no longer corrupts memory or crashes when the encoding back-end reallocates the buffer or gives it a typeglob or shared hash key scalar.
The buffer scalar supplied may now only contain code points 0xFF or lower. [perl #109828]
This fixes a bug detecting the VOS operating system.
The option --libpods has been reinstated. It is deprecated, and its use does nothing other than issue a warning that it is no longer supported.
Since the HTML files generated by pod2html claim to have a UTF-8 charset, actually write the files out using UTF-8 [perl #111446].
Numerous improvements have been made, mostly to Pod::Simple::XHTML, which also has a compatibility change: the codes_in_verbatim option is now disabled by default. See cpan/Pod-Simple/ChangeLog for the full details.
Single character [class]es like /[s]/ or /[s]/i are now optimized as if they did not have the brackets, i.e. /s/ or /s/i.
See note about op_comp in the "Internal Changes" section below.
Fix interactions with Devel::Cover.
Don't eval code under no strict.
Fix an overloading issue with sum.
first and reduce now check the callback first (so &first(1) is disallowed).
Fix tainted on magical values [rt.cpan.org #55763].
Fix sum on previously magical values [rt.cpan.org #61118].
Fix reading past the end of a fixed buffer [rt.cpan.org #72700].
No longer require stat on filehandles.
Use fc for casefolding.
Constants and functions required for IP multicast source group membership have been added.
unpack_sockaddr_in() and unpack_sockaddr_in6() now return just the IP address in scalar context, and inet_ntop() now guards against incorrect length scalars being passed in.
This fixes an uninitialized memory read.
Modifying $_[0] within STORABLE_freeze no longer results in crashes [perl #112358].
An object whose class implements STORABLE_attach is now thawed only once when there are multiple references to it in the structure being thawed [perl #111918].
Restricted hashes were not always thawed correctly [perl #73972].
Storable would croak when freezing a blessed REF object with a STORABLE_freeze() method [perl #113880].
It can now freeze and thaw vstrings correctly. This causes a slight incompatible change in the storage format, so the format version has increased to 2.9.
This contains various bugfixes, including compatibility fixes for older versions of Perl and vstring handling.
This contains several bug fixes relating to getservbyname(), setlogsock()and log levels in syslog(), together with fixes for Windows, Haiku-OS and GNU/kFreeBSD. See cpan/Sys-Syslog/Changes for the full details.
Add support for italics.
Improve error handling.
Fix glob semantics on Win32 [rt.cpan.org #49732].
Don't use Win32::GetShortPathName when calling perl [rt.cpan.org #47890].
Ignore -T when reading shebang [rt.cpan.org #64404].
Handle the case where we don't know the wait status of the test more gracefully.
Make the test summary 'ok' line overridable so that it can be changed to a plugin to make the output of prove idempotent.
Don't run world-writable files.
This adds the option to warn about or ignore attempts to clone structures that can't be cloned, as opposed to just unconditionally dying in that case.
This adds support for dual-valued values as created by Scalar::Util::dualvar.
READ now respects the offset argument to read [perl #112826].
Seconds values greater than 59 but less than 60 no longer cause timegm() and timelocal() to croak.
This adds a function all_casefolds() that returns all the casefolds.
New APIs have been added for getting and setting the current code page.
pipe is now documented.our.dump, goto, next, last and redo) have always had the same precedence as assignment operators, but this was not documented until now.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.
This message now occurs when a here document label has an initial quotation mark but the final quotation mark is missing.
This replaces a bogus and misleading error message about not finding the label itself [perl #114104].
This error is thrown when a child pseudo-process in the ithreads implementation on Windows was not scheduled within the time period allowed and therefore was not able to initialize properly [perl #88840].
This error has been added for (?&0), which is invalid. It used to produce an incomprehensible error message [perl #101666].
Calling an undefined value as a subroutine now produces this error message. It used to, but was accidentally disabled, first in Perl 5.004 for non-magical variables, and then in Perl v5.14 for magical (e.g., tied) variables. It has now been restored. In the mean time, undef was treated as an empty string [perl #113576].
To use lexical subs, you must first enable them:
no warnings 'experimental::lexical_subs';
use feature 'lexical_subs';
my sub foo { ... }
(W closure) During compilation, an inner named subroutine or eval is attempting to capture an outer lexical subroutine that is not currently available. This can happen for one of two reasons. First, the lexical subroutine may be declared in an outer anonymous subroutine that has not yet been created. (Remember that named subs are created at compile time, while anonymous subs are created at run-time.) For example,
sub { my sub a {...} sub f { \&a } }
At the time that f is created, it can't capture the current the "a" sub, since the anonymous subroutine hasn't been created yet. Conversely, the following won't give a warning since the anonymous subroutine has by now been created and is live:
sub { my sub a {...} eval 'sub f { \&a }' }->();
The second situation is caused by an eval accessing a variable that has gone out of scope, for example,
sub f {
my sub a {...}
sub { eval '\&a' }
}
f()->();
Here, when the '\&a' in the eval is being compiled, f() is not currently being executed, so its &a is not available for capture.
(W misc) A "my" or "state" subroutine has been redeclared in the current scope or statement, effectively eliminating all access to the previous instance. This is almost always a typographical error. Note that the earlier subroutine will still exist until the end of the scope or until all closure references to it are destroyed.
(S experimental) This warning is emitted if you enable an experimental feature via use feature. Simply suppress the warning if you want to use the feature, but know that in doing so you are taking the risk of using an experimental feature which may change or be removed in a future Perl version:
no warnings "experimental::lexical_subs"; use feature "lexical_subs";
(W overflow) You called sleep with a number that was larger than it can reliably handle and sleep probably slept for less time than requested.
Attempts to put wide characters into environment variables via %ENV now provoke this warning.
chr() now warns when passed a negative value [perl #83048].
srand() now warns when passed a value that doesn't fit in a UV (since the value will be truncated rather than overflowing) [perl #40605].
Running perl with the -i flag now warns if no input files are provided on the command line [perl #113410].
The warning that use of $* and $# is no longer supported is now generated for every location that references them. Previously it would fail to be generated if another variable using the same typeglob was seen first (e.g. @* before $*), and would not be generated for the second and subsequent uses. (It's hard to fix the failure to generate warnings at all without also generating them every time, and warning every time is consistent with the warnings that $[ used to generate.)
\b{ and \B{ were added. They are a deprecation warning which should be turned off by that category. One should not have to turn off regular regexp warnings as well to get rid of these.
Constant overloading that returns undef results in this error message. For numeric constants, it used to say "Constant(undef)". "undef" has been replaced with the number itself.
This warning was not suppressible, even with no warnings. Now it is suppressible, and has been moved from the "internal" category to the "printf" category.
Can't do {n,m} with n > m in regex; marked by <-- HERE in m/%s/This fatal error has been turned into a warning that reads:
Quantifier {n,m} with n > m can't match in regex
(W regexp) Minima should be less than or equal to maxima. If you really want your regexp to match something 0 times, just put {0}.
useversionedarchname option to ConfigureWhen set, it includes 'api_versionstring' in 'archname'. E.g. x86_64-linux-5.13.6-thread-multi. It is unset by default.
This feature was requested by Tim Bunce, who observed that INSTALL_BASE creates a library structure that does not differentiate by perl version. Instead, it places architecture specific files in "$install_base/lib/perl5/$archname". This makes it difficult to use a common INSTALL_BASE library path with multiple versions of perl.
By setting -Duseversionedarchname, the $archname will be distinct for architecture and API version, allowing mixed use of INSTALL_BASE.
PERL_NO_INLINE_FUNCTIONS option
If PERL_NO_INLINE_FUNCTIONS is defined, don't include "inline.h"
This permits test code to include the perl headers for definitions without creating a link dependency on the perl library (which may not exist yet).
MAILDOMAIN environment variable, if set.installman no longer ignores the silent optionMETA.yml and META.json files are now included in the distribution.isblank() when compiling with a C++ compiler.PERL_TEST_MEMORY environment variable to the number of gibibytes of memory that may be safely used.BeOS was an operating system for personal computers developed by Be Inc, initially for their BeBox hardware. The OS Haiku was written as an open source replacement for/continuation of BeOS, and its perl port is current and actively maintained.
Support code relating to UTS global has been removed. UTS was a mainframe version of System V created by Amdahl, subsequently sold to UTS Global. The port has not been touched since before Perl v5.8.0, and UTS Global is now defunct.
Support for VM/ESA has been removed. The port was tested on 2.3.0, which IBM ended service on in March 2002. 2.4.0 ended service in June 2003, and was superseded by Z/VM. The current version of Z/VM is V6.2.0, and scheduled for end of service on 2015/04/30.
Support for MPE/IX has been removed.
Support code relating to EPOC has been removed. EPOC was a family of operating systems developed by Psion for mobile devices. It was the predecessor of Symbian. The port was last updated in April 2002.
Support for Rhapsody has been removed.
Configure now always adds -qlanglvl=extc99 to the CC flags on AIX when using xlC. This will make it easier to compile a number of XS-based modules that assume C99 [perl #113778].
There is now a workaround for a compiler bug that prevented compiling with clang++ since Perl v5.15.7 [perl #112786].
When compiling the Perl core as C++ (which is only semi-supported), the mathom functions are now compiled as extern "C", to ensure proper binary compatibility. (However, binary compatibility isn't generally guaranteed anyway in the situations where this would matter.)
Stop hardcoding an alignment on 8 byte boundaries to fix builds using -Dusemorebits.
Perl should now work out of the box on Haiku R1 Alpha 4.
libc_r was removed from recent versions of MidnightBSD and older versions work better with pthread. Threading is now enabled using pthread which corrects build errors with threading enabled on 0.4-CURRENT.
In Configure, avoid running sed commands with flags not supported on Solaris.
DECC$EFS_CASE_PRESERVE and DECC$ARGV_PARSE_STYLE at start-up time. The latter only takes effect when extended parse is enabled in the process from which Perl is run.DECC$EFS_CHARSET to DISABLE.-Dusemymalloc=y.-Dusecxx.system, backticks, or a piped open. Previously, quotes on the verb were passed through to DCL, which would fail to recognize the command. Also, if the verb is actually a path to an image or command procedure on an ODS-5 volume, quoting it now allows the path to contain spaces.USE_SOCKETS_AS_HANDLES has been removed.link on Win32 now attempts to set $! to more appropriate values based on the Win32 API error code. [perl #112272]
Perl no longer mangles the environment block, e.g. when launching a new sub-process, when the environment contains non-ASCII characters. Known problems still remain, however, when the environment contains characters outside of the current ANSI codepage (e.g. see the item about Unicode in %ENV in http://perl5.git.perl.org/perl.git/blob/HEAD:/Porting/todo.pod). [perl #113536]
glob operator (which uses the perlglob program) deleting the PATH environment variable [perl #113798].USE_64_BIT_INT, has been added to the Windows makefiles. Set this to "define" when building a 32-bit perl if you want it to use 64-bit integers.Machine code size reductions, already made to the DLLs of XS modules in Perl v5.17.2, have now been extended to the perl DLL itself.
Building with VC++ 6.0 was inadvertently broken in Perl v5.17.2 but has now been fixed again.
Building on WinCE is now possible once again, although more work is required to fully restore a clean build.
av_len() have been created: av_top_index() and av_tindex. All three of these return the number of the highest index in the array, not the number of elements it contains.So this is now a syntax error:
if (!SvUPGRADE(sv)) { croak(...); }
If you have code like that, simply replace it with
SvUPGRADE(sv);
or to avoid compiler warnings with older perls, possibly
(void)SvUPGRADE(sv);
It can be enabled in a perl build by running Configure with -Accflags=-DPERL_NEW_COPY_ON_WRITE, and we would encourage XS authors to try their code with such an enabled perl, and provide feedback. Unfortunately, there is not yet a good guide to updating XS code to cope with COW. Until such a document is available, consult the perl5-porters mailing list.
It breaks a few XS modules by allowing copy-on-write scalars to go through code paths that never encountered them before.
Use the SvIsCOW macro (as before) to identify a copy-on-write scalar.
PL_glob_index is gone.SvREADONLY returns false on such an SV, but SvIsCOW still returns true.OP_PADRANGE has been introduced. The perl peephole optimiser will, where possible, substitute a single padrange op for a pushmark followed by one or more pad ops, and possibly also skipping list and nextstate ops. In addition, the op can carry out the tasks associated with the RHS of a my(...) = @_ assignment, so those ops may be optimised away too.PL_formfeed has been removed.PL_compcv now points to the currently-compiling subroutine, rather than the BEGIN block itself.mg_length has been deprecated.sv_len now always returns a byte count and sv_len_utf8 a character count. Previously, sv_len and sv_len_utf8 were both buggy and would sometimes returns bytes and sometimes characters. sv_len_utf8 no longer assumes that its argument is in UTF-8. Neither of these creates UTF-8 caches for tied or overloaded values or for non-PVs any more.sv_mortalcopy now copies string buffers of shared hash key scalars when called from XS modules [perl #79824].RXf_MODIFIES_VARS flag can be set by custom regular expression engines to indicate that the execution of the regular expression may cause variables to be modified. This lets s/// know to skip certain optimisations. Perl's own regular expression engine sets this flag for the special backtracking verbs that set $REGMARK and $REGERROR.
PADLISTs are now longer AVs, but their own type instead. PADLISTs now contain a PAD and a PADNAMELIST of PADNAMEs, rather than AVs for the pad and the list of pad names. PADs, PADNAMELISTs, and PADNAMEs are to be accessed as such through the newly added pad API instead of the plain AV and SV APIs. See perlapi for details.
$`, $&, $& variables. Previously the same three values were used to retrieve ${^PREMATCH}, ${^MATCH}, ${^POSTMATCH} too, but these have now been assigned three separate values. See "Numbered capture callbacks" in perlreapi.PL_sawampersand was previously a boolean indicating that any of $`, $&, $& had been seen; it now contains three one-bit flags indicating the presence of each of the variables individually.CV * typemap entry now supports &{} overloading and typeglobs, just like &{...} [perl #96872].SVf_AMAGIC flag to indicate overloading is now on the stash, not the object. It is now set automatically whenever a method or @ISA changes, so its meaning has changed, too. It now means "potentially overloaded". When the overload table is calculated, the flag is automatically turned off if there is no overloading, so there should be no noticeable slowdown.
The staleness of the overload tables is now checked when overload methods are invoked, rather than during bless.
"A" magic is gone. The changes to the handling of the SVf_AMAGIC flag eliminate the need for it.
PL_amagic_generation has been removed as no longer necessary. For XS modules, it is now a macro alias to PL_na.
The fallback overload setting is now stored in a stash entry separate from overloadedness itself.
study function was made a no-op in v5.16. It was simply disabled via a return statement; the code was left in place. Now the code supporting what study used to do has been removed.cop->stashpv). Instead, there is an offset (cop->stashoff) into the new PL_stashpad array, which holds stash pointers.regexp_engine struct has acquired a new field op_comp, which is currently just for perl's internal use, and should be initialized to NULL by other regex plugin modules.alloccopstash has been added to the API, but is considered experimental. See perlapi.PERL_DEBUG_READONLY_OPS has been rewritten to work with the new slab allocator, allowing it to catch more violations than before.PERL_IMPLICIT_SYS and PERL_DEBUG_READONLY_OPS, has been retired.-DPERL_GLOBAL_STRUCT builds now free the global struct after they've finished using it.:crlf layer now works when unread data doesn't fit into its own buffer. [perl #112244].ungetc() now handles UTF-8 encoded data. [perl #116322].sort {undef} ... under fatal warnings no longer crashes. It had begun crashing in Perl v5.16.bless \%Foo::, 'Bar'; bless \%Bar::, 'Foo') no longer result in double frees. This bug started happening in Perl v5.16.'f' =~ /../g were not resetting pos. Also, "match-once" patterns (m?...?g) failed to reset it, too, when invoked a second time [perl #23180].local *ISA and local *Foo:: causing stale MRO caches have been fixed.local *method=... would fail to reset method caches upon scope exit./[.foo.]/ is no longer an error, but produces a warning (as before) and is treated as /[.fo]/ [perl #115818].goto $tied_var now calls FETCH before deciding what type of goto (subroutine or label) this is.*Foo:: = *Bar::; *Bar:: = *Baz::) in combination with m?...? and reset no longer makes threaded builds crash.(1, 1, 1, 1).scalar(%h = (1, 1, 1, 1)) now returns 4, not 2.%h = (1, 1, 1) in list context was wrong. Previously this would return (1, undef, 1), now it returns (1, undef).($s, %h) = (1, {}) as it does for (%h) = ({}), "Reference found where even-sized list expected".dump, goto, last, next, redo or require followed by a bareword (or version) and then an infix operator is no longer a syntax error. It used to be for those infix operators (like +) that have a different meaning where a term is expected. [perl #105924]require a::b . 1 and require a::b + 1 no longer produce erroneous ambiguity warnings. [perl #107002]qr// used in m/// no longer triggers the "empty pattern reuses last pattern" behaviour. [perl #96230]%^H) is tied, compile-time scope entry (which copies the hint hash) no longer leaks memory if FETCH dies. [perl #107000]split " " behaviour. [perl #94490]defined scalar(@array), defined do { &foo }, and similar constructs now treat the argument to defined as a simple scalar. [perl #97466]*DB::DB glob or provides a subroutine stub for &DB::DB no longer results in a crash, but an error instead. [perl #114990]reset "" now matches its documentation. reset only resets m?...? patterns when called with no argument. An empty string for an argument now does nothing. (It used to be treated as no argument.) [perl #97958]printf with an argument returning an empty list no longer reads past the end of the stack, resulting in erratic behaviour. [perl #77094]--subname no longer produces erroneous ambiguity warnings. [perl #77240]v10 is now allowed as a label or package name. This was inadvertently broken when v-strings were added in Perl v5.6. [perl #56880]length, pos, substr and sprintf could be confused by ties, overloading, references and typeglobs if the stringification of such changed the internal representation to or from UTF-8. [perl #114410]$tied =~ s/$non_utf8/$utf8/ no longer loops infinitely if the tied variable returns a Latin-1 string, shared hash key scalar, or reference or typeglob that stringifies as ASCII or Latin-1. This was a regression from v5.12.s/// without /e is now better at detecting when it needs to forego certain optimisations, fixing some buggy cases:&&, ||, .. and others) in the replacement part; e.g., s/(.)/$l{$a||$1}/g. [perl #26986]$REGERROR or $REGMARK in the replacement. [perl #49190]s//$foo/) that causes the last-successful pattern to be used, when that pattern contains code blocks that modify the variables in the replacement.s///e.$| autoflush variable is created on-the-fly when needed. If this happened (e.g., if it was mentioned in a module or eval) when the currently-selected filehandle was a typeglob with an empty IO slot, it used to crash. [perl #115206]length($object) no longer returns the undefined value if the object has string overloading that returns undef. [perl #115260]PL_stashcache, the stash name lookup cache for method calls, has been restored,
Commit da6b625f78f5f133 in August 2011 inadvertently broke the code that looks up values in PL_stashcache. As it's only a cache, quite correctly everything carried on working without it.
local %$ref appeared on the last line of an lvalue subroutine. This error disappeared for \local %$ref in perl v5.8.1. It has now been restored.s/${s|||}//) no longer confuses the parser.s//"" # hello/e has always worked, unless there happens to be a null character before the first #. Now it works even in the presence of nulls.tr/// or y/// no longer results in a memory leak.eval 'q;;') as a syntax error.warn {$_ => 1} + 1 is no longer a syntax error. The parser used to get confused with certain list operators followed by an anonymous hash and then an infix operator that shares its form with a unary operator.(caller $n)[6] (which gives the text of the eval) used to return the actual parser buffer. Modifying it could result in crashes. Now it always returns a copy. The string returned no longer has "\n;" tacked on to the end. The returned text also includes here-doc bodies, which used to be omitted.$& etc)$_ = 'x' x 1_000_000; 1 while /(.)/;
used to skip the buffer copy for performance reasons, but suffered from $1 etc changing if the original string changed. That's now been fixed.
{n,m} where n > m$obj->SUPER::method calls in the main package could fail if the SUPER package had already been accessed by other means.*foo:: = *bar::) no longer causes SUPER calls to ignore changes to methods or @ISA or use the wrong package.\w now matches the code points U+200C (ZERO WIDTH NON-JOINER) and U+200D (ZERO WIDTH JOINER). \W no longer matches these. This change is because Unicode corrected their definition of what \w should match.dump LABEL no longer leaks its label.stat() and truncate() that can take either filenames or handles. stat 1 ? foo : bar nows treats its argument as a file name (since it is an arbitrary expression), rather than the handle "foo".truncate FOO, $len no longer falls back to treating "FOO" as a file name if the filehandle has been deleted. This was broken in Perl v5.16.0.s/// now turns vstrings into plain strings when performing a substitution, even if the resulting string is the same (s/a/a/).undef on a subroutine now clears call checkers.ref operator started leaking memory on blessed objects in Perl v5.16.0. This has been fixed [perl #114340].use no longer tries to parse its arguments as a statement, making use constant { () }; a syntax error [perl #114222].use statements are now permitted inside formats.print $x and sub { print $x }->() now always produce the same output. It was possible for the latter to refuse to close over $x if the variable was not active; e.g., if it was defined outside a currently-running named subroutine.print $x and print eval '$x' now produce the same output. This also allows "my $x if 0" variables to be seen in the debugger [perl #114018].= and .), but only sometimes. Semicolons and low-precedence operators in format argument lines no longer confuse the parser into ignoring the line's return value. In format argument lines, braces can now be used for anonymous hashes, instead of being treated always as do blocks./(?{...})/ and qq/${...}/) [perl #114040].require() could potentially read one or two bytes before the start of the filename for filenames less than three bytes long and ending /\.p?\z/. This has now been fixed. Note that it could never have happened with module names given to use() or require() anyway.require() has been made thread-safe on VMS.goto '' now looks for an empty label, producing the "goto must have label" error message, instead of exiting the program [perl #111794].goto "\0" now dies with "Can't find label" instead of "goto must have label".hv_store used to result in crashes when used on %^H [perl #111000].cv_set_call_checker is now copied to closures cloned from it. So cv_set_call_checker now works inside an attribute handler for a closure.$^N used to have no effect. Now it croaks with "Modification of a read-only value" by default, but that can be overridden by a custom regular expression engine, as with $1 [perl #112184].undef on a control character glob (undef *^H) no longer emits an erroneous warning about ambiguity [perl #112456].print &CORE::uc("a"), &CORE::uc("b") used to print "BB". The same thing would happen with an lvalue subroutine returning the return value of uc. Now the value is copied in such cases.method {} syntax with an empty block or a block returning an empty list used to crash or use some random value left on the stack as its invocant. Now it produces an error.vec now works with extremely large offsets (>2 GB) [perl #111730].bless.
Objects that were created before a class had any overloading used to remain non-overloaded even if the class gained overloading through use overload or @ISA changes, and even after bless. This has been fixed [perl #112708].
+= [perl #111856].pos now croaks with hash and array arguments, instead of producing erroneous warnings.while(each %h) now implies while(defined($_ = each %h)), like readline and readdir.undef *_ when called with no argument list (&CORE::time with no parentheses).unpack no longer produces the "'/' must follow a numeric type in unpack" error when it is the data that are at fault [perl #60204].join and "@array" now call FETCH only once on a tied $" [perl #8931].CORE::GLOBAL override had op checking performed twice. The checking is always idempotent for pure Perl code, but the double checking can matter when custom call checkers are involved.(?{}) and (??{}), has been heavily reworked to eliminate a whole slew of bugs. The main user-visible changes are:
/(?{ $x='{' })/
This means that this error message is no longer generated:
Sequence (?{...}) not terminated or not {}-balanced in regex
but a new error may be seen:
Sequence (?{...}) not terminated with ')'
In addition, literal code blocks within run-time patterns are only compiled once, at perl compile-time:
for my $p (...) {
# this 'FOO' block of code is compiled once,
# at the same time as the surrounding 'for' loop
/$p{(?{FOO;})/;
}
/A(?{B})C/ behaves (from a closure viewpoint) exactly like /A/ && do { B } && /C/, while qr/A(?{B})C/ is like sub {/A/ && do { B } && /C/}. So this code now works how you might expect, creating three regexes that match 0, 1, and 2:
for my $i (0..2) {
push @r, qr/^(??{$i})$/;
}
"1" =~ $r[1]; # matches
use re 'eval' pragma is now only required for code blocks defined at runtime; in particular in the following, the text of the $r pattern is still interpolated into the new pattern and recompiled, but the individual compiled code-blocks within $r are reused rather than being recompiled, and use re 'eval' isn't needed any more:
my $r = qr/abc(?{....})def/;
/xyz$r/;
next etc. will not see any enclosing loops. return returns a value from the code block, not from any enclosing subroutine.
my $code = '(??{$x})';
for my $x (1..3) {
# recompile to see fresh value of $x each time
$x =~ /$code/;
}
/msix and (?msix) etc. flags are now propagated into the return value from (??{}); this now works:
"AB" =~ /a(??{'b'})/i;
re_eval:
use re 'eval'; $c = '(?{ warn "foo" })'; /$c/;
/(?{ warn "foo" })/;
formerly gave:
foo at (re_eval 1) line 1. foo at (re_eval 2) line 1.
and now gives:
foo at (eval 1) line 1. foo at /some/prog line 2.
vec no longer produces "uninitialized" warnings in lvalue context [perl #9423].(?:) or (?:|)) could disable some optimizations. This has been fixed.prototype produces when passed a string like "CORE::nonexistent_keyword" now passes UTF-8 and embedded NULs through unchanged [perl #97478].prototype now treats magical variables like $1 the same way as non-magical variables when checking for the CORE:: prefix, instead of treating them as subroutine names.caller, and possibly crashes [perl #113060].\&{$_[1]} in an attribute handler for a closure) no longer results in a copy of the subroutine (or assertion failures on debugging builds).eval '__PACKAGE__' now returns the right answer on threaded builds if the current package has been assigned over (as in *ThisPackage:: = *ThatPackage::) [perl #78742].caller to see a stack frame belonging to that deleted package. caller could crash if the stash's memory address was reused for a scalar and a substitution was performed on the same scalar [perl #113486].UNIVERSAL::can no longer treats its first argument differently depending on whether it is a string or number internally.open with <& for the mode checks to see whether the third argument is a number, in determining whether to treat it as a file descriptor or a handle name. Magical variables like $1 were always failing the numeric check and being treated as handle names.warn's handling of magical variables ($1, ties) has undergone several fixes. FETCH is only called once now on a tied argument or a tied $@ [perl #97480]. Tied variables returning objects that stringify as "" are no longer ignored. A tied $@ that happened to return a reference the previous time it was used is no longer ignored.warn "" now treats $@ with a number in it the same way, regardless of whether it happened via $@=3 or $@="3". It used to ignore the former. Now it appends "\t...caught", as it has always done with $@="3".$1 + 1$x contains the string "dogs", -$x returns "-dogs" even if $y=0+$x has happened at some point.-'-10' was fixed to return "10", not "+10". But magical variables ($1, ties) were not fixed till now [perl #57706].UTF8 flag.tr/SEARCHLIST/REPLACEMENTLIST/ has been fixed. Only the first instance is supposed to be meaningful if a character appears more than once in SEARCHLIST. Under some circumstances, the final instance was overriding all earlier ones. [perl #113584]qr/\87/ previously silently inserted a NUL character, thus matching as if it had been written qr/\00087/. Now it matches as if it had been written as qr/87/, with a message that the sequence "\8" is unrecognized.__SUB__ now works in special blocks (BEGIN, END, etc.).BEGIN block. It still does not work properly, but it no longer crashes [perl #111610].\&{''} (with the empty string) now autovivifies a stub like any other sub name, and no longer produces the "Unable to create sub" error [perl #94476].re module would clobber $_ [perl #113750].do FILE now always either sets or clears $@, even when the file can't be read. This ensures that testing $@ first (as recommended by the documentation) always returns the correct result.each @array construct is now correctly reset when @array is cleared [perl #75596]. This happens, for example, when the array is globally assigned to, as in @array = (...), but not when its values are assigned to. In terms of the XS API, it means that av_clear() will now reset the iterator.This mirrors the behaviour of the hash iterator when the hash is cleared.
$class->can, $class->isa, and $class->DOES now return correct results, regardless of whether that package referred to by $class exists [perl #47113].$@ [perl #45173].my () declarations with an empty variable list [perl #113554].qr// expressions no longer crash with custom regular expression engines that do not set offs at regular expression compilation time [perl #112962].delete local no longer crashes with certain magical arrays and hashes [perl #112966].local on elements of certain magical arrays and hashes used not to arrange to have the element deleted on scope exit, even if the element did not exist before local.scalar(write) no longer returns multiple items [perl #73690].use locale [perl #109318].@INC filters that die no longer leak memory [perl #92252].<> [perl #47119].fallback key when calling use overload now behaves properly [perl #113010].sub foo { my $a = 0; while ($a) { ... } } and sub foo { while (0) { ... } } now return the same thing [perl #73618].use integer; as it does without [perl #113012].chr now returns the Unicode replacement character (U+FFFD) for -1, regardless of the internal representation. -1 used to wrap if the argument was tied or a string internally.format after its enclosing sub was freed could crash as of perl v5.12.0, if the format referenced lexical variables from the outer sub.format after its enclosing sub was undefined could crash as of perl v5.10.0, if the format referenced lexical variables from the outer sub.format defined inside a closure, which format references lexical variables from outside, never really worked unless the write call was directly inside the closure. In v5.10.0 it even started crashing. Now the copy of that closure nearest the top of the call stack is used to find those variables.eval foo () as a syntax error if preceded by print; [perl #16249].syscall is no longer truncated on 64-bit platforms [perl #113980].print 1 ? FOO : BAR to print to the FOO handle [perl #78064].do subname now calls the named subroutine and uses the file name it returns, instead of opening a file named "subname".foo bar should be the sub call foo(bar) or the method call "bar"->foo.CORE::foo::bar is no longer treated specially, allowing global overrides to be called directly via CORE::GLOBAL::uc(...) [perl #113016].*ISA = *glob_without_array and undef *ISA; @{*ISA} would prevent future modifications to @ISA from updating the internal caches used to look up methods. The *glob_without_array case was a regression from Perl v5.12.$ with /m to produce failed or incorrect matches [perl #114068].__SUB__ now works in a sort block when the enclosing subroutine is predeclared with sub foo; syntax [perl #113710].\w and [:word:] should not generate the warning, as their definitions don't limit them to apply to only Unicode code points. Now the message is only generated when matching against \p{} and \P{}. There remains a bug, [perl #114148], for the very few properties in Unicode that match just a single code point. The warning is not generated if they are matched against an above-Unicode code point."/\n\n" =~ m#\A(?:^/$)#im would not match [perl #115242].fork in list context no longer corrupts the stack. @a = (1, 2, fork, 3) used to gobble up the 2 and assign (1, undef, 3) if the fork call failed.${qr//}) to a variable that happens to hold a floating point number no longer causes assertion failures on debugging builds.$byte_overload .= $utf8 no longer results in doubly-encoded UTF-8 if the left-hand scalar happened to have produced a UTF-8 string the last time overloading was invoked.goto &sub now uses the current value of @_, instead of using the array the subroutine was originally called with. This means local @_ = (...); goto &sub now works [perl #43077].*_{ARRAY} returned from a subroutine no longer spontaneously becomes empty.say to print to a tied filehandle, the value of $\ is correctly localized, even if it was previously undef. [perl #119927]%ENV on HP-UX 11.00 are buggy
The interaction of UTF8-flagged strings and %ENV on HP-UX 11.00 is currently dodgy in some not-yet-fully-diagnosed way. Expect test failures in t/op/magic.t, followed by unknown behavior when storing wide characters in the environment.
Hojung Yoon (AMORETTE), 24, of Seoul, South Korea, went to his long rest on May 8, 2013 with llama figurine and autographed TIMTOADY card. He was a brilliant young Perl 5 & 6 hacker and a devoted member of Seoul.pm. He programmed Perl, talked Perl, ate Perl, and loved Perl. We believe that he is still programming in Perl with his broken IBM laptop somewhere. He will be missed.
Perl v5.18.0 represents approximately 12 months of development since Perl v5.16.0 and contains approximately 400,000 lines of changes across 2,100 files from 113 authors.
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 v5.18.0:
Aaron Crane, Aaron Trevena, Abhijit Menon-Sen, Adrian M. Enache, Alan Haggai Alavi, Alexandr Ciornii, Andrew Tam, Andy Dougherty, Anton Nikishaev, Aristotle Pagaltzis, Augustina Blair, Bob Ernst, Brad Gilbert, Breno G. de Oliveira, Brian Carlson, Brian Fraser, Charlie Gonzalez, Chip Salzenberg, Chris 'BinGOs' Williams, Christian Hansen, Colin Kuskie, Craig A. Berry, Dagfinn Ilmari Mannsåker, Daniel Dragan, Daniel Perrett, Darin McBride, Dave Rolsky, David Golden, David Leadbeater, David Mitchell, David Nicol, Dominic Hargreaves, E. Choroba, Eric Brine, Evan Miller, Father Chrysostomos, Florian Ragwitz, François Perrad, George Greer, Goro Fuji, H.Merijn Brand, Herbert Breunung, Hugo van der Sanden, Igor Zaytsev, James E Keenan, Jan Dubois, Jasmine Ahuja, Jerry D. Hedden, Jess Robinson, Jesse Luehrs, Joaquin Ferrero, Joel Berger, John Goodyear, John Peacock, Karen Etheridge, Karl Williamson, Karthik Rajagopalan, Kent Fredric, Leon Timmermans, Lucas Holt, Lukas Mai, Marcus Holland-Moritz, Markus Jansen, Martin Hasch, Matthew Horsfall, Max Maischein, Michael G Schwern, Michael Schroeder, Moritz Lenz, Nicholas Clark, Niko Tyni, Oleg Nesterov, Patrik Hägglund, Paul Green, Paul Johnson, Paul Marquess, Peter Martini, Rafael Garcia-Suarez, Reini Urban, Renee Baecker, Rhesa Rozendaal, Ricardo Signes, Robin Barker, Ronald J. Kimball, Ruslan Zakirov, Salvador Fandiño, Sawyer X, Scott Lanning, Sergey Alekseev, Shawn M Moore, Shirakata Kentaro, Shlomi Fish, Sisyphus, Smylers, Steffen Müller, Steve Hay, Steve Peters, Steven Schubiger, Sullivan Beck, Sven Strickroth, Sébastien Aperghis-Tramoni, Thomas Sibley, Tobias Leich, Tom Wyant, Tony Cook, Vadim Konovalov, Vincent Pit, Volker Schatz, Walt Mankowski, Yves Orton, Zefram.
The list above is almost certainly incomplete as it is automatically generated from version control history. In particular, it does not include the names of the (very much appreciated) contributors who reported issues to the Perl bug tracker.
Many of the changes included in this version originated in the CPAN modules included in Perl's core. We're grateful to the entire CPAN community for helping Perl to flourish.
For a more complete list of all of Perl's historical contributors, please see the AUTHORS file in the Perl source distribution.
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@perl.org to be analysed by the Perl porting team.
If the bug you are reporting has security implications, which make it inappropriate to send to a publicly archived mailing list, then please send it to perl5-security-report@perl.org. This points to a closed subscription unarchived mailing list, which includes all the core committers, who will be able to help assess the impact of issues, figure out a resolution, and help co-ordinate the release of patches to mitigate or fix the problem across all platforms on which Perl is supported. Please only use this address for security issues in the Perl core, not for modules independently distributed on CPAN.
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.