Merge branch 'drolsky/release-5.15.6' into blead

[perl5.git] / pod / perldelta.pod

=encoding utf8

=head1 NAME

perldelta - what is new for perl v5.15.6

=head1 DESCRIPTION

This document describes differences between the 5.15.5 release and the
5.15.6 release.

If you are upgrading from an earlier release such as 5.15.4, first read
L<perl5155delta>, which describes differences between 5.15.4 and
5.15.5.

=head1 Core Enhancements

=head2 C<__SUB__>

The new C<__SUB__> token, available under the "current_sub" feature
(see L<feature>) or C<use v5.15>, returns a reference to the current
subroutine, making it easier to write recursive closures.

=head2 New option for the debugger's B<t> command

The B<t> command in the debugger, which toggles tracing mode, now
accepts a numeric argument that determines how many levels of
subroutine calls to trace.

=head2 Return value of C<tied>

The value returned by C<tied> on a tied variable is now the actual
scalar that holds the object to which the variable is tied.  This
allows ties to be weakened with C<Scalar::Util::weaken(tied
$tied_variable)>.

=head1 Security

=head2 C<is_utf8_char()>

The XS-callable function C<is_utf8_char()>, when presented with
malformed UTF-8 input, can read up to 12 bytes beyond the end of the
string.  This cannot be fixed without changing its API.  It is not
called from CPAN.  The documentation now describes how to use it
safely.

=head2 Other C<is_utf8_foo()> functions, as well as C<utf8_to_foo()>, etc.

Most of the other XS-callable functions that take UTF-8 encoded input
implicitly assume that the UTF-8 is valid (not malformed) in regards to
buffer length.  Do not do things such as change a character's case or
see if it is alphanumeric without first being sure that it is valid
UTF-8.  This can be safely done for a whole string by using one of the
functions C<is_utf8_string()>, C<is_utf8_string_loc()>, and
C<is_utf8_string_loclen()>.

=head2 C<use I<VERSION>>

As of this release, version declarations like C<use v5.16> now disable
all features before enabling the new feature bundle.  This means that
the following holds true:

    use 5.016;
    # 5.16 features enabled here
    use 5.014;
    # 5.16 features disabled here

C<use v5.12> and higher continue to enable strict, but explicit C<use
strict> and C<no strict> now override the version declaration, even
when they come first:

    no strict;
    use 5.012;
    # no strict here

There is a new ":default" feature bundle that represents the set of
features enabled before any version declaration or C<use feature> has
been seen.  Version declarations below 5.10 now enable the ":default"
feature set.  This does not actually change the behaviour of C<use
v5.8>, because features added to the ":default" set are those that were
traditionally enabled by default, before they could be turned off.

C<$[> is now disabled under C<use v5.16>.  It is part of the default
feature set and can be turned on or off explicitly with C<use feature
'array_base'>.

=head2 C<UNIVERSAL::VERSION>

The change to C<UNIVERSAL::VERSION> in 5.15.2 has been reverted.  It
now returns a stringified version object once more.

=head2 C<substr> lvalue revamp

When C<substr> is called in lvalue or potential lvalue context with two
or three arguments, a special lvalue scalar is returned that modifies
the original string (the first argument) when assigned to.

Previously, the offsets (the second and third arguments) passed to
C<substr> would be converted immediately to match the string, negative
offsets being translated to positive and offsets beyond the end of the
string being truncated.

Now, the offsets are recorded without modification in the special
lvalue scalar that is returned, and the original string is not even
looked at by C<substr> itself, but only when the returned lvalue is
read or modified.

These changes result in several incompatible changes and bug fixes:

=over

=item *

If the original string changes length after the call to C<substr> but
before assignment to its return value, negative offsets will remember
their position from the end of the string, affecting code like this:

    my $string = "string";
    my $lvalue = \substr $string, -4, 2;
    print $lvalue, "\n"; # prints "ri"
    $string = "bailing twine";
    print $lvalue, "\n"; # prints "wi"; used to print "il"

The same thing happens with an omitted third argument.  The returned
lvalue will always extend to the end of the string, even if the string
becomes longer.

=item *

Tied (and otherwise magical) variables are no longer exempt from the
"Attempt to use reference as lvalue in substr" warning.

=item *

That warning now occurs when the returned lvalue is assigned to, not
when C<substr> itself is called.  This only makes a difference if the
return value of C<substr> is referenced and assigned to later.

=item *

The order in which "uninitialized" warnings occur for arguments to
C<substr> has changed.

=item *

Passing a substring of a read-only value or a typeglob to a function
(potential lvalue context) no longer causes an immediate "Can't coerce"
or "Modification of a read-only value" error.  That error only occurs
if and when the value passed is assigned to.

The same thing happens with the "substr outside of string" error.  If
the lvalue is only read, not written to, it is now just a warning, as
with rvalue C<substr>.

=item *

C<substr> assignments no longer call FETCH twice if the first argument
is a tied variable, just once.

=back

It was impossible to fix all the bugs without an incompatible change,
and the behaviour of negative offsets was never specified, so the
change was deemed acceptable.

=head2 Return value of C<eval>

C<eval> returns C<undef> in scalar context or an empty list in list
context when there is a run-time error.  When C<eval> was passed a
string in list context and a syntax error occurred, it used to return a
list containing a single undefined element.  Now it returns an empty
list in list context for all errors [perl #80630].

=head2 Anonymous handles

Automatically generated file handles are now named __ANONIO__ when the
variable name cannot be determined, rather than $__ANONIO__.

=head2 Last-accessed filehandle

Perl has an internal variable that stores the last filehandle to be
accessed.  It is used by C<$.> and by C<tell> and C<eof> without
arguments.

It used to be possible to set this internal variable to a glob copy and
then modify that glob copy to be something other than a glob, and still
have the last-accessed filehandle associated with the variable after
assigning a glob to it again:

    my $foo = *STDOUT;  # $foo is a glob copy
    <$foo>;             # $foo is now the last-accessed handle
    $foo = 3;           # no longer a glob
    $foo = *STDERR;     # still the last-accessed handle

Now the C<$foo = 3> assignment unsets that internal variable, so there
is no last-accessed filehandle, just as if C<< <$foo> >> had never
happened.

=head2 XS API tweak

The C<newCONSTSUB_flags> C-level function, added in 5.15.4, now has a
C<len> parameter.

=head1 Performance Enhancements

=over 4

=item *

Perl 5.12.0 sped up the destruction of objects whose classes define
empty C<DESTROY> methods (to prevent autoloading), by simply not
calling such empty methods.  This release takes this optimisation a
step further, by not calling any C<DESTROY> method that begins with a
C<return> statement.  This can be useful for destructors that are only
used for debugging:

    use constant DEBUG => 1;
    sub DESTROY { return unless DEBUG; ... }

Constant-folding will reduce the first statement to C<return;> if DEBUG
is set to 0, triggering this optimisation.

=item *

Assigning to a variable that holds a typeglob or copy-on-write scalar
is now much faster.  Previously the typeglob would be stringified or
the copy-on-write scalar would be copied before being clobbered.

=item *

Assignment to C<substr> in void context is now more than twice its
previous speed.  Instead of creating and returning a special lvalue
scalar that is then assigned to, C<substr> modifies the original string
itself.

=back

=head1 Modules and Pragmata

=head2 Updated Modules and Pragmata

=over 4

=item *

L<Archive::Tar> has been upgraded from version 1.80 to version 1.82.

Adjustments to handle files >8gb (>0777777777777 octal) and a feature
to return the MD5SUM of files in the archive.

=item *

L<AutoLoader> has been upgraded from version 5.71 to version 5.72.

=item *

L<B::Debug> has been upgraded from version 1.16 to version 1.17.

=item *

L<B::Deparse> has been upgraded from version 1.09 to version 1.10.

Various constructs that used to be deparsed incorrectly have been
fixed:

=over

=item C<sort(foo(bar))>

It used to deparse as C<sort foo(bar)>, which makes foo the sort
routine, rather than a regular function call.

=item Keys and values in C<%^H>

Undefined values in the hint hash were being deparsed as empty strings.
Whenever the hint hash changed, all undefined values, even those
unmodified, were being printed.

Special characters, such as quotation marks, were not being escaped
properly.

Some values used to be omitted if, for instance, a key was the same as
a previous value and vice versa.

=item "method BLOCK" syntax

C<method { $expr }> used to be deparsed as something like C<< do{ $expr
}->method >>, but the latter puts the $expr in scalar context, whereas
the former puts in list context.

=item C<do +{}> and C<do({})>

These are both variants of do-file syntax, but were being deparsed as
do-blocks.

=item Keywords that do not follow the llaf rule

Keywords like C<return> and C<last> that do not follow the
looks-like-a-function rule are now deparsed correctly with parentheses
in the right place.

Similarly, C<not>, which I<does> follow the llaf rule, was being
deparsed as though it does not.

=item C<=~>

In various cases, B::Deparse started adding a spurious C<$_ =~> before
the right-hand side in Perl 5.14; e.g., C<< "" =~ <$a> >> would become
C<< "" =~ ($_ =~ <$a>) >>.

=item C<open local *FH>

C<open>, C<pipe> and other functions that autovivify handles used to
omit C<local *> from C<local *FH>.

=item Negated single-letter subroutine calls

Negated subroutine calls like C<- f()> and C<-(f())> were being
deparsed as file test operators.

=item C<&{&}>

C<&{&}> and C<& &>, which are calls to the subroutine named "&",
believe it or not, were being deparsed as C<&&>.

=item C<require $this + $that>

In Perl 5.14, C<require> followed by any binary operator started
deparsing as C<no>.

=back

=item *

L<Carp> has been upgraded from version 1.23 to version 1.24.

It now tacks the last-accessed filehandle and line number on to the end
of the error message, just like C<die> [perl #96672].

=item *

L<Compress::Raw::Zlib> has been upgraded from version 2.042 to version
2.045.

=item *

L<Compress::Raw::Bzip2> has been upgraded from version 2.042 to version
2.045.

=item *

L<CPAN::Meta::YAML> has been upgraded from version 0.004 to version
0.005.

=item *

L<CPANPLUS> has been upgraded from version 0.9112 to version 0.9114.

=item *

L<Data::Dumper> has been upgraded from version 2.134 to version 2.135.

The XS implementation has been updated to account for the Unicode
symbol changes in Perl 5.15.4.  It also knows how to output typeglobs
with nulls in their names.

=item *

L<diagnostics> has been upgraded from version 1.25 to version 1.26.

It now understands the "%X" format code, which some error messages
started using in Perl 5.14.0.

=item *

L<Digest::SHA> has been upgraded from version 5.63 to version 5.70.

Added BITS mode to the addfile method and shasum.  This makes
partial-byte inputs possible via files/STDIN and allows shasum to check
all 8074 NIST Msg vectors, where previously special programming was
required to do this.

=item *

L<Exporter> has been upgraded from version 5.65 to version 5.66.

It no longer tries to localise C<$_> unnecessarily.

=item *

L<ExtUtils::ParseXS> has been upgraded from version 3.05 to version
3.07.

=item *

L<IO::Compress::Base> has been upgraded from version 2.042 to version
2.046.

Added zipdetails utility.

=item *

L<Locale::Codes> has been upgraded from version 3.18 to version 3.20.

The code2XXX, XXX2code, all_XXX_codes, and all_XXX_names functions now
support retired codes.  All codesets may be specified by a constant or
by their name now.  Previously, they were specified only by a constant.

The alias_code function exists for backward compatibility.  It has been
replaced by rename_country_code.  The alias_code function will be
removed some time after September, 2013.

All work is now done in the central module (Locale::Codes). 
Previously, some was still done in the wrapper modules
(Locale::Codes::*).  Added Language Family codes (langfam) as defined
in ISO 639-5.

=item *

L<Module::CoreList> has been upgraded from version 2.58 to version
2.59.

=item *

L<Module::Loaded> has been upgraded from version 0.06 to version 0.08.

=item *

L<Pod::LaTeX> has been upgraded from version 0.59 to version 0.60.

Added another LaTeX escape: --- => -{}-{}-

Pod::LaTeX doesn't handle -- in PODs specially, passing it directly to
LaTeX, which then proceeds to replace it with a single -.  This patch
replaces ----- with -{}-{}-{}-{}-

=item *

L<POSIX> has been upgraded from version 1.26 to version 1.27.

It no longer produces a "Constant subroutine TCSANOW redefined" warning
on Windows.

This bug was introduced in Perl 5.15.3.

=item *

L<Socket> has been upgraded from version 1.94_02 to version 1.97.

=item *

L<threads> has been upgraded from version 1.85 to version 1.86.

=item *

L<Unicode::Collate> has been upgraded from version 0.85 to version
0.87.

Tailored compatibility ideographs as well as unified ideographs for the
locales: ja, ko, zh__big5han, zh__gb2312han, zh__pinyin, zh__stroke.

Locale/*.pl files are now searched for in @INC.

=item *

L<UNIVERSAL> has been upgraded from version 1.10 to version 1.11.

Documentation change clarifies return values from UNIVERSAL::VERSION.

=back

=head2 Removed Modules and Pragmata

=over 4

=item *

Changing the case of a UTF-8 encoded string under C<use locale> now
gives better, but still imperfect, results.  Previously, such a string
would entirely lose locale semantics and silently be treated as
Unicode.  Now, the code points that are less than 256 are treated with
locale rules, while those above 255 are, of course, treated as Unicode.
 See L<perlfunc/lc> for more details, including the deficiencies of
this scheme.

=back

=head1 Documentation

=head2 Changes to Existing Documentation

=head3 L<perlsec/Laundering and Detecting Tainted Data>

=over 4

=item *

The example function for checking for taintedness contained a subtle
error.  C<$@> needs to be localized to prevent its changing this
global's value outside the function.  The preferred method to check for
this remains L<Scalar::Util/tainted>.

=back

=head1 Diagnostics

=head2 Changes to Existing Diagnostics

=over 4

=item *

Redefinition warnings for constant subroutines used to be mandatory,
even occurring under C<no warnings>.  Now they respect the L<warnings>
pragma.

=item *

The "Attempt to free non-existent shared string" has had the spelling
of "non-existent" corrected to "nonexistent".  It was already listed
with the correct spelling in L<perldiag>.

=item *

The 'Use of "foo" without parentheses is ambiguous' warning has been
extended to apply also to user-defined subroutines with a (;$)
prototype, and not just to built-in functions.

=item *

The error messages for using C<default> and C<when> outside of a
topicalizer have been standardised to match the messages for
C<continue> and loop controls.  They now read 'Can't "default" outside
a topicalizer' and 'Can't "when" outside a topicalizer'.  They both
used to be 'Can't use when() outside a topicalizer' [perl #91514].

=back

=head1 Utility Changes

=head3 L<zipdetails>

=over 4

=item *

L<zipdetails> displays information about the internal record structure
of the zip file.  It is not concerned with displaying any details of
the compressed data stored in the zip file.

=back

=head1 Configuration and Compilation

=over 4

=item *

F<pod/roffitall> is now built by F<pod/buildtoc>, instead of being
shipped with the distribution.  Its list of manpages is now generated
(and therefore current).  See also RT #103202 for an unresolved related
issue.

=item *

Perl 5.15.5 had a bug in its installation script, which did not install
F<unicore/Name.pm>.  This has been corrected [perl #104226].

=item *

The man page for C<XS::Typemap> is no longer installed.  C<XS::Typemap>
is a test module which is not installed, hence installing its
documentation makes no sense.

=for 5.16.0 Merge this with the entry for "Stop installing XS::APItest*"

=item *

The man pages for the perl FAQ, L<perlxs>, L<perlxstut> and L<perldoc>
are once again correctly installed in F<man1>, not F<man3>

=for 5.16.0 This isn't a regression from 5.14.x, so don't mention this.

=item *

The -Dusesitecustomize and -Duserelocatableinc options now work
together properly.

=back

=head1 Testing

=over 4

=item *

The F<substr.t> and F<substr_thr.t> scripts for testing C<substr> have
been moved under F<t/op/>, where they were originally.  They had been
moved under F<t/re/> along with the substitution tests when that
directory was created.

=back

=head1 Platform Support

=head2 Platform-Specific Notes

=head3 VMS

=over 4

=item *

A link-time error on VMS versions without C<symlink> support was
introduced in 5.15.1, but has now been corrected.

=item *

Explicit support for VMS versions prior to v7.0 and DEC C versions
prior to v6.0 has been removed.

=item *

Since Perl 5.10.1, the home-grown C<stat> wrapper has been unable to
distinguish between a directory name containing an underscore and an
otherwise-identical filename containing a dot in the same position
(e.g., t/test_pl as a directory and t/test.pl as a file).  This problem
has been corrected.

=back

=head1 Selected Bug Fixes

=over 4

=item *

RT #78266: The regex engine has been leaking memory when accessing
named captures that weren't matched as part of a regex ever since 5.10
when they were introduced, e.g. this would consume over a hundred MB of
memory:

    for (1..10_000_000) {
        if ("foo" =~ /(foo|(?<capture>bar))?/) {
            my $capture = $+{capture}
        }
    }
    system "ps -o rss $$"'

=item *

A constant subroutine assigned to a glob whose name contains a null
will no longer cause extra globs to pop into existence when the
constant is referenced under its new name.

=item *

C<sort> was not treating C<sub {}> and C<sub {()}> as equivalent when
such a sub was provided as the comparison routine.  It used to croak on
C<sub {()}>.

=item *

Subroutines from the C<autouse> namespace are once more exempt from
redefinition warnings.  This used to work in 5.005, but was broken in
5.6 for most subroutines.  For subs created via XS that redefine
subroutines from the C<autouse> package, this stopped working in 5.10.

=item *

New XSUBs now produce redefinition warnings if they overwrite existing
subs, as they did in 5.8.x.  (The C<autouse> logic was reversed in
5.10-14.  Only subroutines from the C<autouse> namespace would warn
when clobbered.)

=item *

Redefinition warnings triggered by the creation of XSUBs now respect
Unicode glob names, instead of using the internal representation.  This
was missed in 5.15.4, partly because this warning was so hard to
trigger.  (See the previous item.)

=item *

C<newCONSTSUB> used to use compile-time warning hints, instead of
run-time hints.  The following code should never produce a redefinition
warning, but it used to, if C<newCONSTSUB> redefined an existing
subroutine:

    use warnings;
    BEGIN {
        no warnings;
        some_XS_function_that_calls_new_CONSTSUB();
    }

=item *

Redefinition warnings for constant subroutines are on by default (what
are known as severe warnings in L<perldiag>).  This was only the case
when it was a glob assignment or declaration of a Perl subroutine that
caused the warning.  If the creation of XSUBs triggered the warning, it
was not a default warning.  This has been corrected.

=item *

The internal check to see whether a redefinition warning should occur
used to emit "uninitialized" warnings in cases like this:

    use warnings "uninitialized";
    use constant {u => undef, v => undef};
    sub foo(){u}
    sub foo(){v}

=item *

A bug fix in Perl 5.14 introduced a new bug, causing "uninitialized"
warnings to report the wrong variable if the operator in question had
two operands and one was C<%{...}> or C<@{...}>.  This has been fixed
[perl #103766].

=item *

C<< version->new("version") >> and C<printf "%vd", "version"> no longer
crash [perl #102586].

=item *

C<$tied =~ y/a/b/>, C<chop $tied> and C<chomp $tied> now call FETCH
just once when $tied holds a reference.

=item *

Four-argument C<select> now always calls FETCH on tied arguments.  It
used to skip the call if the tied argument happened to hold C<undef> or
a typeglob.

=item *

Four-argument C<select> no longer produces its "Non-string passed as
bitmask" warning on tied or tainted variables that are strings.

=item *

C<sysread> now always calls FETCH on the buffer passed to it if the
buffer is tied.  It used to skip the call if the tied variable happened
to hold a typeglob.

=item *

C<< $tied .= <> >> now calls FETCH once on C<$tied>.  It used to call
it multiple times if the last value assigned to or returned from the
tied variable was anything other than a string or typeglob.

=item *

The C<evalbytes> keyword added in 5.15.5 was respecting C<use utf8>
declarations from the outer scope, when it should have been ignoring
them.

=item *

C<goto &func> no longer crashes, but produces an error message, when
the unwinding of the current subroutine's scope fires a destructor that
undefines the subroutine being "goneto" [perl #99850].

=item *

Arithmetic assignment (C<$left += $right>) involving overloaded objects
that rely on the 'nomethod' override no longer segfault when the left
operand is not overloaded.

=item *

Assigning C<__PACKAGE__> or any other shared hash key scalar to a stash
element no longer causes a double free.  Regardless of this change, the
results of such assignments are still undefined.

=item *

Assigning C<__PACKAGE__> or another shared hash key string to a
variable no longer stops that variable from being tied if it happens to
be a PVMG or PVLV internally.

=item *

Creating a C<UNIVERSAL::AUTOLOAD> sub no longer stops C<%+>, C<%-> and
C<%!> from working some of the time [perl #105024].

=item *

When presented with malformed UTF-8 input, the XS-callable functions
C<is_utf8_string()>, C<is_utf8_string_loc()>, and
C<is_utf8_string_loclen()> could read beyond the end of the input
string by up to 12 bytes.  This no longer happens.  [perl #32080].
However, currently, C<is_utf8_char()> still has this defect, see
L</is_utf8_char()> above.

=item *

Doing a substitution on a tied variable returning a copy-on-write
scalar used to cause an assertion failure or an "Attempt to free
nonexistent shared string" warning.

=item *

A change in perl 5.15.4 caused C<caller()> to produce malloc errors and
a crash with Perl's own malloc, and possibly with other malloc
implementations, too [perl #104034].

=item *

A bug fix in 5.15.5 could sometimes result in assertion failures under
debugging builds of perl for certain syntax errors in C<eval>, such as
C<eval q|""!=!~//|>

=item *

The "c [line num]" debugger command was broken by other debugger
changes released in 5.15.3.  This is now fixed.

=item *

Breakpoints were not properly restored after a debugger restart using
the "R" command.  This was broken in 5.15.3.  This is now fixed.

=item *

The debugger prompt did not display the current line.  This was broken
in 5.15.3.  This is now fixed.

=item *

Class method calls still suffered from the Unicode bug with Latin-1
package names.  This was missed in the Unicode package name cleanup in
5.15.4 [perl #105922].

=item *

The debugger no longer tries to do C<local $_> when dumping data
structures.

=item *

Calling C<readline($fh)> where $fh is a glob copy (e.g., after C<$fh =
*STDOUT>), assigning something other than a glob to $fh, and then
freeing $fh (e.g., by leaving the scope where it is defined) no longer
causes the internal variable used by C<$.> (C<PL_last_in_gv>) to point
to a freed scalar, that could be reused for some other glob, causing
C<$.> to use some unrelated filehandle [perl #97988].

=item *

A regression in 5.14 caused these statements not to set the internal
variable that holds the handle used by C<$.>:

    my $fh = *STDOUT;
    tell $fh;
    eof  $fh;
    seek $fh, 0,0;
    tell     *$fh;
    eof      *$fh;
    seek     *$fh, 0,0;
    readline *$fh;

This is now fixed, but C<tell *{ *$fh }> still has the problem, and it
is not clear how to fix it [perl #106536].

=item *

Version comparisons, such as those that happen implicitly with C<use
v5.43>, no longer cause locale settings to change [perl #105784].

=item *

F<pod/buildtoc>, which generates L<perltoc>, put path names in the
L<perltoc> file.  This bug was introduced in 5.15.1.

=back

=head1 Acknowledgments

Perl 5.15.6 represents approximately 2 months of development since Perl
5.15.5 and contains approximately 48,000 lines of changes across 560
files from 36 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 5.15.6:

Aaron Crane, Abhijit Menon-Sen, Alexandr Ciornii, Brian Fraser, Carl
Hayter, Chris 'BinGOs' Williams, Craig A. Berry, Dave Rolsky, David
Golden, David Mitchell, Dominic Hargreaves, Father Chrysostomos, James
E Keenan, Johannes Plunien, John Peacock, Karl Williamson, Marc Green,
Mark Dootson, Matthew Horsfall, Nicholas Clark, Paul Evans, Peter
Martini, Peter Scott, Rafael Garcia-Suarez, Reini Urban, Ricardo
Signes, Rodolfo Carvalho, Shlomi Fish, Steffen Müller, Steve Hay,
Steve Peters, Thomas Sibley, Timothe Litt, Tony Cook, Vadim Konovalov,
Ævar Arnfjörð Bjarmason.

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

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

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

=head1 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 L<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 C<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.

=head1 SEE ALSO

The F<Changes> file for an explanation of how to view exhaustive
details on what changed.

The F<INSTALL> file for how to build Perl.

The F<README> file for general stuff.

The F<Artistic> and F<Copying> files for copyright information.

=cut