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1=encoding utf8
2
3=head1 NAME
4
5076a392 5perldelta - what is new for perl v5.14.0
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7=head1 DESCRIPTION
8
9This document describes differences between the 5.12.0 release and
10the 5.14.0 release.
11
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12If you are upgrading from an earlier release such as 5.10.0, first read
13L<perl5120delta>, which describes differences between 5.10.0 and
145.12.0.
15
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16Some of the bug fixes in this release have been backported to subsequent
17releases of 5.12.x. Those are indicated with the 5.12.x version in
18parentheses.
19
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20=head1 Notice
21
22XXX Any important notices here
23
24=head1 Core Enhancements
25
1f539a1a 26=head2 Unicode
5076a392 27
1f539a1a 28=head3 Unicode Version 6.0 is now supported (mostly)
5076a392 29
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30Perl comes with the Unicode 6.0 data base updated with
31L<Corrigendum #8|http://www.unicode.org/versions/corrigendum8.html>,
32with one exception noted below.
33See L<http://unicode.org/versions/Unicode6.0.0> for details on the new
34release. Perl does not support any Unicode provisional properties,
a3c24add 35including the new ones for this release.
5076a392 36
1f539a1a 37Unicode 6.0 has chosen to use the name C<BELL> for the character at U+1F514,
e1b1739f 38which is a symbol that looks like a bell, and is used in Japanese cell
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39phones. This conflicts with the long-standing Perl usage of having
40C<BELL> mean the ASCII C<BEL> character, U+0007. In Perl 5.14,
41C<\N{BELL}> will continue to mean U+0007, but its use will generate a
42deprecated warning message, unless such warnings are turned off. The
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43new name for U+0007 in Perl is C<ALERT>, which corresponds nicely
44with the existing shorthand sequence for it, C<"\a">. C<\N{BEL}>
45means U+0007, with no warning given. The character at U+1F514 will not
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46have a name in 5.14, but can be referred to by C<\N{U+1F514}>. The plan
47is that in Perl 5.16, C<\N{BELL}> will refer to U+1F514, and so all code
48that uses C<\N{BELL}> should convert by then to using C<\N{ALERT}>,
49C<\N{BEL}>, or C<"\a"> instead.
5076a392 50
1f539a1a 51=head3 Full functionality for C<use feature 'unicode_strings'>
5076a392 52
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53This release provides full functionality for C<use feature
54'unicode_strings'>. Under its scope, all string operations executed and
55regular expressions compiled (even if executed outside its scope) have
56Unicode semantics. See L<feature>.
5076a392 57
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58This feature avoids most forms of the "Unicode Bug" (See
59L<perlunicode/The "Unicode Bug"> for details.) If there is a
60possibility that your code will process Unicode strings, you are
61B<strongly> encouraged to use this subpragma to avoid nasty surprises.
5076a392 62
1f539a1a 63=head3 C<\N{I<name>}> and C<charnames> enhancements
5076a392 64
1f539a1a 65=over
5076a392 66
1f539a1a 67=item *
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68
69C<\N{}> and C<charnames::vianame> now know about the abbreviated
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70character names listed by Unicode, such as NBSP, SHY, LRO, ZWJ, etc., all
71the customary abbreviations for the C0 and C1 control characters (such as
72ACK, BEL, CAN, etc.), and a few new variants of some C1 full names that
73are in common usage.
5076a392 74
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75=item *
76
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77Unicode has a number of named character sequences, in which particular sequences
78of code points are given names. C<\N{...}> now recognizes these.
79
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80=item *
81
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82C<\N{}>, C<charnames::vianame>, C<charnames::viacode> now know about every
83character in Unicode. Previously, they didn't know about the Hangul syllables
84nor a number of CJK (Chinese/Japanese/Korean) characters.
85
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86=item *
87
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88In the past, it was ineffective to override one of Perl's abbreviations
89with your own custom alias. Now it works.
90
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91=item *
92
e1b1739f 93You can also create a custom alias of the ordinal of a
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94character, known by C<\N{...}>, C<charnames::vianame()>, and
95C<charnames::viacode()>. Previously, an alias had to be to an official
96Unicode character name. This made it impossible to create an alias for
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97a code point that had no name, such as those reserved for private
98use.
5076a392 99
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100=item *
101
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102A new function, C<charnames::string_vianame()>, has been added.
103This function is a run-time version of C<\N{...}>, returning the string
104of characters whose Unicode name is its parameter. It can handle
105Unicode named character sequences, whereas the pre-existing
106C<charnames::vianame()> cannot, as the latter returns a single code
107point.
108
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109=back
110
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111See L<charnames> for details on all these changes.
112
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113=head3 New warnings categories for problematic (non-)Unicode code points.
114
115Three new warnings subcategories of "utf8" have been added. These
116allow you to turn off some "utf8" warnings, while allowing
117others warnings to remain on. The three categories are:
118C<surrogate> when UTF-16 surrogates are encountered;
119C<nonchar> when Unicode non-character code points are encountered;
120and C<non_unicode> when code points that are above the legal Unicode
121maximum of 0x10FFFF are encountered.
122
1f539a1a 123=head3 Any unsigned value can be encoded as a character
5076a392 124
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125With this release, Perl is adopting a model that any unsigned value can
126be treated as a code point and encoded internally (as utf8) without
54c7bb16 127warnings - not just the code points that are legal in Unicode.
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128However, unless utf8 or the corresponding sub-category (see previous
129item) warnings have been
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130explicitly lexically turned off, outputting or performing a
131Unicode-defined operation (such as upper-casing) on such a code point
132will generate a warning. Attempting to input these using strict rules
133(such as with the C<:encoding('UTF-8')> layer) will continue to fail.
134Prior to this release the handling was very inconsistent, and incorrect
135in places. Also, the Unicode non-characters, some of which previously were
136erroneously considered illegal in places by Perl, contrary to the Unicode
137standard, are now always legal internally. But inputting or outputting
138them will work the same as for the non-legal Unicode code points, as the
139Unicode standard says they are illegal for "open interchange".
5076a392 140
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141=head3 Unicode database files not installed
142
143The Unicode database files are no longer installed with Perl. This
144doesn't affect any functionality in Perl and saves significant disk
145space. If you previously were explicitly opening and reading those
146files, you can download them from
147L<http://www.unicode.org/Public/zipped/6.0.0/>.
148
1f539a1a 149=head2 Regular Expressions
5076a392 150
1f539a1a 151=head3 C<(?^...)> construct to signify default modifiers
5076a392 152
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153An ASCII caret (also called a "circumflex accent") C<"^">
154immediately following a C<"(?"> in a regular expression
155now means that the subexpression does not inherit the
156surrounding modifiers such as C</i>, but reverts to the
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157Perl defaults. Any modifiers following the caret override the defaults.
158
159The stringification of regular expressions now uses this
160notation. E.g., before, C<qr/hlagh/i> would be stringified as
161C<(?i-xsm:hlagh)>, but now it's stringified as C<(?^i:hlagh)>.
162
163The main purpose of this is to allow tests that rely on the
e1b1739f 164stringification not to have to change when new modifiers are added.
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165See L<perlre/Extended Patterns>.
166
1f539a1a 167=head3 C</d>, C</l>, C</u>, C</a>, and C</aa> modifiers
5076a392 168
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169Four new regular expression modifiers have been added. These are mutually
170exclusive; one only can be turned on at a time.
5076a392 171
959ad7d5 172The C</l> modifier says to compile the regular expression as if it were
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173in the scope of C<use locale>, even if it is not.
174
959ad7d5 175The C</u> modifier says to compile the regular expression as if it were
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176in the scope of a C<use feature "unicode_strings"> pragma.
177
e1b1739f 178The C</d> (default) modifier is used to override any C<use locale> and
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179C<use feature "unicode_strings"> pragmas that are in effect at the time
180of compiling the regular expression.
181
959ad7d5 182The C</a> regular expression modifier restricts C<\s>, C<\d> and C<\w> and
7baaf023 183the Posix (C<[[:posix:]]>) character classes to the ASCII range. Their
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184complements and C<\b> and C<\B> are correspondingly
185affected. Otherwise, C</a> behaves like the C</u> modifier, in that
e1b1739f 186case-insensitive matching uses Unicode semantics.
5076a392 187
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188The C</aa> modifier is like C</a>, except that, in case-insensitive matching, no ASCII character will match a
189non-ASCII character. For example,
5076a392 190
959ad7d5 191 'k' =~ /\N{KELVIN SIGN}/ai
5076a392 192
959ad7d5 193will match; it won't under C</aa>.
5076a392 194
959ad7d5 195See L<perlre/Modifiers> for more detail.
5076a392 196
1f539a1a 197=head3 Non-destructive substitution
5076a392 198
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199The substitution (C<s///>) and transliteration
200(C<y///>) operators now support an C</r> option that
201copies the input variable, carries out the substitution on
202the copy and returns the result. The original remains unmodified.
5076a392 203
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204 my $old = 'cat';
205 my $new = $old =~ s/cat/dog/r;
206 # $old is 'cat' and $new is 'dog'
5076a392 207
1f539a1a 208This is particularly useful with C<map>. See L<perlop> for more examples.
5076a392 209
1f539a1a 210=head3 Reentrant regular expression engine
5076a392 211
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212It is now safe to use regular expressions within C<(?{...})> and
213C<(??{...})> code blocks inside regular expressions.
5076a392 214
1f539a1a 215These block are still experimental, however, and still have problems with
e1b1739f 216lexical (C<my>) variables and abnormal exiting.
5076a392 217
1f539a1a 218=head3 C<use re '/flags';>
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219
220The C<re> pragma now has the ability to turn on regular expression flags
221till the end of the lexical scope:
222
223 use re '/x';
224 "foo" =~ / (.+) /; # /x implied
225
226See L<re/"'/flags' mode"> for details.
227
1f539a1a 228=head3 \o{...} for octals
5076a392 229
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230There is a new octal escape sequence, C<"\o">, in double-quote-like
231contexts. This construct allows large octal ordinals beyond the
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232current max of 0777 to be represented. It also allows you to specify a
233character in octal which can safely be concatenated with other regex
234snippets and which won't be confused with being a backreference to
235a regex capture group. See L<perlre/Capture groups>.
236
237=head3 Add C<\p{Titlecase}> as a synonym for C<\p{Title}>
238
239This synonym is added for symmetry with the Unicode property names
240C<\p{Uppercase}> and C<\p{Lowercase}>.
5076a392 241
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242=head3 Regular expression debugging output improvement
243
244Regular expression debugging output (turned on by C<use re 'debug';>) now
245uses hexadecimal when escaping non-ASCII characters, instead of octal.
246
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247=head3 Return value of C<delete $+{...}>
248
249Custom regular expression engines can now determine the return value of
250C<delete> on an entry of C<%+> or C<%->.
251
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252=head2 Syntactical Enhancements
253
254=head3 Array and hash container functions accept references
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255
256All built-in functions that operate directly on array or hash
257containers now also accept hard references to arrays or hashes:
258
259 |----------------------------+---------------------------|
260 | Traditional syntax | Terse syntax |
261 |----------------------------+---------------------------|
262 | push @$arrayref, @stuff | push $arrayref, @stuff |
263 | unshift @$arrayref, @stuff | unshift $arrayref, @stuff |
264 | pop @$arrayref | pop $arrayref |
265 | shift @$arrayref | shift $arrayref |
266 | splice @$arrayref, 0, 2 | splice $arrayref, 0, 2 |
267 | keys %$hashref | keys $hashref |
268 | keys @$arrayref | keys $arrayref |
269 | values %$hashref | values $hashref |
270 | values @$arrayref | values $arrayref |
271 | ($k,$v) = each %$hashref | ($k,$v) = each $hashref |
272 | ($k,$v) = each @$arrayref | ($k,$v) = each $arrayref |
273 |----------------------------+---------------------------|
274
275This allows these built-in functions to act on long dereferencing chains
276or on the return value of subroutines without needing to wrap them in
277C<@{}> or C<%{}>:
278
279 push @{$obj->tags}, $new_tag; # old way
280 push $obj->tags, $new_tag; # new way
281
282 for ( keys %{$hoh->{genres}{artists}} ) {...} # old way
283 for ( keys $hoh->{genres}{artists} ) {...} # new way
284
285For C<push>, C<unshift> and C<splice>, the reference will auto-vivify
286if it is not defined, just as if it were wrapped with C<@{}>.
287
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288For C<keys>, C<values>, C<each>, when overloaded dereferencing is
289present, the overloaded dereference is used instead of dereferencing the
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290underlying reftype. Warnings are issued about assumptions made in
291ambiguous cases.
5076a392 292
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293=head3 Single term prototype
294
295The C<+> prototype is a special alternative to C<$> that will act like
296C<\[@%]> when given a literal array or hash variable, but will otherwise
e1b1739f 297force scalar context on the argument. See L<perlsub/Prototypes>.
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298
299=head3 C<package> block syntax
300
301A package declaration can now contain a code block, in which case the
302declaration is in scope only inside that block. So C<package Foo { ... }>
303is precisely equivalent to C<{ package Foo; ... }>. It also works with
304a version number in the declaration, as in C<package Foo 1.2 { ... }>.
e1b1739f 305See L<perlfunc>.
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306
307=head3 Statement labels can appear in more places
308
309Statement labels can now occur before any type of statement or declaration,
310such as C<package>.
311
312=head3 Stacked labels
313
314Multiple statement labels can now appear before a single statement.
315
316=head3 Uppercase X/B allowed in hexadecimal/binary literals
317
318Literals may now use either upper case C<0X...> or C<0B...> prefixes,
319in addition to the already supported C<0x...> and C<0b...>
e1b1739f 320syntax [perl #76296].
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321
322C, Ruby, Python and PHP already supported this syntax, and it makes
323Perl more internally consistent. A round-trip with C<eval sprintf
e1b1739f 324"%#X", 0x10> now returns C<16>, the way C<eval sprintf "%#x", 0x10> does.
1f539a1a 325
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326=head3 Overridable tie functions
327
328C<tie>, C<tied> and C<untie> can now be overridden [perl #75902].
329
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330=head2 Exception Handling
331
332Several changes have been made to the way C<die>, C<warn>, and C<$@>
333behave, in order to make them more reliable and consistent.
334
335When an exception is thrown inside an C<eval>, the exception is no
336longer at risk of being clobbered by code running during unwinding
337(e.g., destructors). Previously, the exception was written into C<$@>
338early in the throwing process, and would be overwritten if C<eval> was
339used internally in the destructor for an object that had to be freed
340while exiting from the outer C<eval>. Now the exception is written
341into C<$@> last thing before exiting the outer C<eval>, so the code
342running immediately thereafter can rely on the value in C<$@> correctly
343corresponding to that C<eval>. (C<$@> is still also set before exiting the
344C<eval>, for the sake of destructors that rely on this.)
345
346Likewise, a C<local $@> inside an C<eval> will no longer clobber any
347exception thrown in its scope. Previously, the restoration of C<$@> upon
348unwinding would overwrite any exception being thrown. Now the exception
349gets to the C<eval> anyway. So C<local $@> is safe before a C<die>.
350
351Exceptions thrown from object destructors no longer modify the C<$@>
352of the surrounding context. (If the surrounding context was exception
353unwinding, this used to be another way to clobber the exception being
354thrown.) Previously such an exception was
355sometimes emitted as a warning, and then either was
356string-appended to the surrounding C<$@> or completely replaced the
357surrounding C<$@>, depending on whether that exception and the surrounding
358C<$@> were strings or objects. Now, an exception in this situation is
359always emitted as a warning, leaving the surrounding C<$@> untouched.
360In addition to object destructors, this also affects any function call
361performed by XS code using the C<G_KEEPERR> flag.
362
363Warnings for C<warn> can now be objects, in the same way as exceptions
364for C<die>. If an object-based warning gets the default handling,
365of writing to standard error, it is stringified as
366before, with the file and line number appended. But
367a C<$SIG{__WARN__}> handler will now receive an
368object-based warning as an object, where previously it was passed the
369result of stringifying the object.
370
371=head2 Other Enhancements
372
373=head3 Assignment to C<$0> sets the legacy process name with C<prctl()> on Linux
374
12f3ad4e 375On Linux the legacy process name is now set with L<prctl(2)>, in
1f539a1a 376addition to altering the POSIX name via C<argv[0]> as perl has done
12f3ad4e 377since version 4.000. Now system utilities that read the legacy process
1f539a1a 378name such as ps, top and killall will recognize the name you set when
12f3ad4e 379assigning to C<$0>. The string you supply will be cut off at 16 bytes;
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380this is a limitation imposed by Linux.
381
382=head3 C<srand()> now returns the seed
383
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384This allows programs that need to have repeatable results not to have to come
385up with their own seed-generating mechanism. Instead, they can use C<srand()>
386and stash the return value for future use. Typical is a test program which
1f539a1a 387has too many combinations to test comprehensively in the time available to it
e1b1739f 388each run. It can test a random subset each time and, should there be a failure,
1f539a1a 389log the seed used for that run so that it can later be used to reproduce the
e1b1739f 390same results.
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391
392=head3 printf-like functions understand post-1980 size modifiers
393
394Perl's printf and sprintf operators, and Perl's internal printf replacement
395function, now understand the C90 size modifiers "hh" (C<char>), "z"
396(C<size_t>), and "t" (C<ptrdiff_t>). Also, when compiled with a C99
397compiler, Perl now understands the size modifier "j" (C<intmax_t>).
398
399So, for example, on any modern machine, C<sprintf('%hhd', 257)> returns '1'.
400
401=head3 New global variable C<${^GLOBAL_PHASE}>
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402
403A new global variable, C<${^GLOBAL_PHASE}>, has been added to allow
404introspection of the current phase of the perl interpreter. It's explained in
405detail in L<perlvar/"${^GLOBAL_PHASE}"> and
406L<perlmod/"BEGIN, UNITCHECK, CHECK, INIT and END">.
407
1f539a1a 408=head3 C<-d:-foo> calls C<Devel::foo::unimport>
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409
410The syntax C<-dI<B<:>foo>> was extended in 5.6.1 to make C<-dI<:fooB<=bar>>>
411equivalent to C<-MDevel::foo=bar>, which expands
412internally to C<use Devel::foo 'bar';>.
413F<perl> now allows prefixing the module name with C<->, with the same
414semantics as C<-M>, I<i.e.>
415
416=over 4
417
418=item C<-d:-foo>
419
420Equivalent to C<-M-Devel::foo>, expands to
421C<no Devel::foo;>, calls C<< Devel::foo->unimport() >>
422if the method exists.
423
424=item C<-d:-foo=bar>
425
426Equivalent to C<-M-Devel::foo=bar>, expands to C<no Devel::foo 'bar';>,
427calls C<< Devel::foo->unimport('bar') >> if the method exists.
428
429=back
430
e1b1739f 431This is particularly useful for suppressing the default actions of a
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432C<Devel::*> module's C<import> method whilst still loading it for debugging.
433
1f539a1a 434=head3 Filehandle method calls load L<IO::File> on demand
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435
436When a method call on a filehandle would die because the method cannot
437be resolved, and L<IO::File> has not been loaded, Perl now loads L<IO::File>
438via C<require> and attempts method resolution again:
439
440 open my $fh, ">", $file;
441 $fh->binmode(":raw"); # loads IO::File and succeeds
442
443This also works for globs like STDOUT, STDERR and STDIN:
444
445 STDOUT->autoflush(1);
446
447Because this on-demand load only happens if method resolution fails, the
448legacy approach of manually loading an L<IO::File> parent class for partial
449method support still works as expected:
450
451 use IO::Handle;
452 open my $fh, ">", $file;
453 $fh->autoflush(1); # IO::File not loaded
454
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455=head3 IPv6 support
456
457The C<Socket> module provides new affordances for IPv6,
458including implementations of the C<Socket::getaddrinfo()> and
459C<Socket::getnameinfo()> functions, along with related constants, and a
460handful of new functions. See L<Socket>.
461
1f539a1a 462=head3 DTrace probes now include package name
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463
464The DTrace probes now include an additional argument (C<arg3>) which contains
465the package the subroutine being entered or left was compiled in.
466
467For example using the following DTrace script:
468
469 perl$target:::sub-entry
470 {
471 printf("%s::%s\n", copyinstr(arg0), copyinstr(arg3));
472 }
473
474and then running:
475
476 perl -e'sub test { }; test'
477
478DTrace will print:
479
480 main::test
481
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482=head2 New C APIs
483
1e463951 484See L</Internal Changes>.
9378886b 485
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486=head1 Security
487
948b8455 488=head2 User-defined regular expression properties
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489
490In L<perlunicode/"User-Defined Character Properties">, it says you can
491create custom properties by defining subroutines whose names begin with
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492"In" or "Is". However, Perl did not actually enforce that naming
493restriction, so \p{foo::bar} could call foo::bar() if it existed. Now this
948b8455 494convention has been enforced.
5076a392 495
948b8455 496Also, Perl no longer allows a tainted regular expression to invoke a
6369b34f 497user-defined property. It simply dies instead [perl #82616].
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498
499=head1 Incompatible Changes
500
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501Perl 5.14.0 is not binary-compatible with any previous stable release.
502
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503In addition to the sections that follow, see L</C API Changes>.
504
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505=head2 Regular Expressions and String Escapes
506
54c7bb16 507=head3 \400-\777
5076a392 508
54c7bb16 509Use of C<\400>-C<\777> in regexes in certain circumstances has given
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510different, anomalous behavior than their use in all other
511double-quote-like contexts. Since 5.10.1, a deprecated warning message
512has been raised when this happens. Now, all double-quote-like contexts
513have the same behavior, namely to be equivalent to C<\x{100}> -
6369b34f 514C<\x{1FF}>, with no deprecation warning. Use of these values in the
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515command line option C<"-0"> retains the current meaning to slurp input
516files whole; previously, this was documented only for C<"-0777">. It is
517recommended, however, because of various ambiguities, to use the new
518C<\o{...}> construct to represent characters in octal.
5076a392 519
61752d82 520=head3 Most C<\p{}> properties are now immune to case-insensitive matching
5076a392 521
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522For most Unicode properties, it doesn't make sense to have them match
523differently under C</i> case-insensitive matching than not. And doing
524so leads to unexpected results and potential security holes. For
525example
5076a392 526
61752d82 527 m/\p{ASCII_Hex_Digit}+/i
5076a392 528
61752d82 529could previously match non-ASCII characters because of the Unicode
4cf6a51f
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530matching rules (although there were a number of bugs with this). Now
531matching under C</i> gives the same results as non-C</i> matching except
532for those few properties where people have come to expect differences,
533namely the ones where casing is an integral part of their meaning, such
534as C<m/\p{Uppercase}/i> and C<m/\p{Lowercase}/i>, both of which match
535the exact same code points, namely those matched by C<m/\p{Cased}/i>.
536Details are in L<perlrecharclass/Unicode Properties>.
5076a392 537
61752d82 538User-defined property handlers that need to match differently under
4cf6a51f 539C</i> must change to read the new boolean parameter passed to them which is
61752d82
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540non-zero if case-insensitive matching is in effect or 0 otherwise. See
541L<perluniprops/User-Defined Character Properties>.
5076a392 542
61752d82 543=head3 \p{} implies Unicode semantics
5076a392 544
61752d82
FC
545Now, a Unicode property match specified in the pattern will indicate
546that the pattern is meant for matching according to Unicode rules, the way
bc15a0a0 547C<\N{}> does.
5076a392 548
61752d82 549=head3 Regular expressions retain their localeness when interpolated
5076a392 550
61752d82
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551Regular expressions compiled under C<"use locale"> now retain this when
552interpolated into a new regular expression compiled outside a
553C<"use locale">, and vice-versa.
5076a392 554
61752d82
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555Previously, a regular expression interpolated into another one inherited
556the localeness of the surrounding one, losing whatever state it
557originally had. This is considered a bug fix, but may trip up code that
558has come to rely on the incorrect behavior.
5076a392 559
61752d82 560=head3 Stringification of regexes has changed
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561
562Default regular expression modifiers are now notated by using
563C<(?^...)>. Code relying on the old stringification will fail. The
564purpose of this is so that when new modifiers are added, such code will
565not have to change (after this one time), as the stringification will
566automatically incorporate the new modifiers.
567
568Code that needs to work properly with both old- and new-style regexes
f318e2e6 569can avoid the whole issue by using (for Perls since 5.9.5; see L<re>):
5076a392
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570
571 use re qw(regexp_pattern);
572 my ($pat, $mods) = regexp_pattern($re_ref);
573
5076a392
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574If the actual stringification is important, or older Perls need to be
575supported, you can use something like the following:
576
577 # Accept both old and new-style stringification
578 my $modifiers = (qr/foobar/ =~ /\Q(?^/) ? '^' : '-xism';
579
580And then use C<$modifiers> instead of C<-xism>.
581
61752d82 582=head3 Run-time code blocks in regular expressions inherit pragmata
5076a392 583
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584Code blocks in regular expressions (C<(?{...})> and C<(??{...})>) used not
585to inherit any pragmata (strict, warnings, etc.) if the regular expression
586was compiled at run time as happens in cases like these two:
5076a392 587
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588 use re 'eval';
589 $foo =~ $bar; # when $bar contains (?{...})
590 $foo =~ /$bar(?{ $finished = 1 })/;
591
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592This was a bug, which has now been fixed. But
593it has the potential to break
61752d82 594any code that was relying on it.
5076a392 595
61752d82 596=head2 Stashes and Package Variables
5076a392 597
61752d82 598=head3 Localised tied hashes and arrays are no longed tied
5076a392 599
61752d82 600In the following:
5076a392 601
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602 tie @a, ...;
603 {
604 local @a;
605 # here, @a is a now a new, untied array
606 }
607 # here, @a refers again to the old, tied array
5076a392 608
61752d82 609The new local array used to be made tied too, which was fairly pointless,
6369b34f 610and has now been fixed. This fix could however potentially cause a change
61752d82 611in behaviour of some code.
5076a392 612
61752d82 613=head3 Stashes are now always defined
5076a392 614
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615C<defined %Foo::> now always returns true, even when no symbols have yet been
616defined in that package.
5076a392 617
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618This is a side effect of removing a special case kludge in the tokeniser,
619added for 5.10.0, to hide side effects of changes to the internal storage of
620hashes that drastically reduce their memory usage overhead.
621
622Calling defined on a stash has been deprecated since 5.6.0, warned on
623lexicals since 5.6.0, and warned for stashes (and other package
6369b34f 624variables) since 5.12.0. C<defined %hash> has always exposed an
61752d82
FC
625implementation detail - emptying a hash by deleting all entries from it does
626not make C<defined %hash> false, hence C<defined %hash> is not valid code to
6369b34f 627determine whether an arbitrary hash is empty. Instead, use the behaviour
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628that an empty C<%hash> always returns false in a scalar context.
629
48b31689
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630=head3 Clearing stashes
631
632Stash list assignment C<%foo:: = ()> used to make the stash anonymous
633temporarily while it was being emptied. Consequently, any of its
634subroutines referenced elsewhere would become anonymous (showing up as
635"(unknown)" in C<caller>). Now they retain their package names, such that
636C<caller> will return the original sub name if there is still a reference
637to its typeglob, or "foo::__ANON__" otherwise [perl #79208].
638
61752d82 639=head3 Dereferencing typeglobs
5076a392
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640
641If you assign a typeglob to a scalar variable:
642
643 $glob = *foo;
644
645the glob that is copied to C<$glob> is marked with a special flag
6369b34f
FC
646indicating that the glob is just a copy. This
647allows subsequent assignments to C<$glob> to
648overwrite the glob. The original glob, however, is
5076a392
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649immutable.
650
370ff23e 651Some Perl operators did not distinguish between these two types of globs.
5076a392 652This would result in strange behaviour in edge cases: C<untie $scalar>
370ff23e 653would not untie the scalar if the last thing assigned to it was a glob
5076a392 654(because it treated it as C<untie *$scalar>, which unties a handle).
f318e2e6 655Assignment to a glob slot (e.g., C<*$glob = \@some_array>) would simply
5076a392
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656assign C<\@some_array> to C<$glob>.
657
658To fix this, the C<*{}> operator (including the C<*foo> and C<*$foo> forms)
659has been modified to make a new immutable glob if its operand is a glob
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FC
660copy. This allows operators that make a distinction between globs and
661scalars to be modified to treat only immutable globs as globs. (C<tie>,
662C<tied> and C<untie> have been left as they are for compatibility's sake,
6369b34f 663but will warn. See L</Deprecations>.)
5076a392
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664
665This causes an incompatible change in code that assigns a glob to the
6369b34f 666return value of C<*{}> when that operator was passed a glob copy. Take the
5076a392
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667following code, for instance:
668
669 $glob = *foo;
670 *$glob = *bar;
671
672The C<*$glob> on the second line returns a new immutable glob. That new
6369b34f 673glob is made an alias to C<*bar>. Then it is discarded. So the second
5076a392
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674assignment has no effect.
675
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676See L<http://rt.perl.org/rt3/Public/Bug/Display.html?id=77810> for even
677more detail.
678
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679=head3 Magic variables outside the main package
680
681In previous versions of Perl, magic variables like C<$!>, C<%SIG>, etc. would
682'leak' into other packages. So C<%foo::SIG> could be used to access signals,
683C<${"foo::!"}> (with strict mode off) to access C's C<errno>, etc.
684
685This was a bug, or an 'unintentional' feature, which caused various ill effects,
686such as signal handlers being wiped when modules were loaded, etc.
687
688This has been fixed (or the feature has been removed, depending on how you see
689it).
690
a8bd2968
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691=head3 local($_) will strip all magic from $_
692
693local() on scalar variables will give them a new value, but keep all
694their magic intact. This has proven to be problematic for the default
695scalar variable $_, where L<perlsub> recommends that any subroutine
696that assigns to $_ should localize it first. This would throw an
697exception if $_ is aliased to a read-only variable, and could have
698various unintentional side-effects in general.
699
700Therefore, as an exception to the general rule, local($_) will not
701only assign a new value to $_, but also remove all existing magic from
702it as well.
703
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704=head3 Parsing of package and variable names
705
706The parsing of the names of packages and package variables has changed, in
707that multiple adjacent pairs of colons (as in foo::::bar) are all treated
708as package separators.
709
710Regardless of this change, the exact parsing of package separators has
711never been guaranteed and is subject to change in future Perl versions.
712
61752d82
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713=head2 Changes to Syntax or to Perl Operators
714
715=head3 C<given> return values
716
717C<given> blocks now return the last evaluated
718expression, or an empty list if the block was exited by C<break>. Thus you
719can now write:
720
721 my $type = do {
722 given ($num) {
723 break when undef;
724 'integer' when /^[+-]?[0-9]+$/;
725 'float' when /^[+-]?[0-9]+(?:\.[0-9]+)?$/;
726 'unknown';
727 }
728 };
729
730See L<perlsyn/Return value> for details.
731
732=head3 Change in the parsing of certain prototypes
733
734Functions declared with the following prototypes now behave correctly as unary
735functions:
736
737 *
738 \$ \% \@ \* \&
739 \[...]
740 ;$ ;*
741 ;\$ ;\% etc.
742 ;\[...]
743
744Due to this bug fix [perl #75904], functions
745using the C<(*)>, C<(;$)> and C<(;*)> prototypes
179813a8
FC
746are parsed with higher precedence than before. So
747in the following example:
61752d82
FC
748
749 sub foo($);
750 foo $a < $b;
751
752the second line is now parsed correctly as C<< foo($a) < $b >>, rather than
179813a8 753C<< foo($a < $b) >>. This happens when one of these operators is used in
61752d82
FC
754an unparenthesised argument:
755
756 < > <= >= lt gt le ge
757 == != <=> eq ne cmp ~~
758 &
759 | ^
760 &&
761 || //
762 .. ...
763 ?:
764 = += -= *= etc.
765
766=head3 Smart-matching against array slices
767
768Previously, the following code resulted in a successful match:
769
770 my @a = qw(a y0 z);
771 my @b = qw(a x0 z);
772 @a[0 .. $#b] ~~ @b;
773
774This odd behaviour has now been fixed [perl #77468].
775
776=head3 Negation treats strings differently from before
777
778The unary negation operator C<-> now treats strings that look like numbers
779as numbers [perl #57706].
780
781=head3 Negative zero
782
783Negative zero (-0.0), when converted to a string, now becomes "0" on all
179813a8 784platforms. It used to become "-0" on some, but "0" on others.
61752d82
FC
785
786If you still need to determine whether a zero is negative, use
787C<sprintf("%g", $zero) =~ /^-/> or the L<Data::Float> module on CPAN.
788
789=head3 C<:=> is now a syntax error
5076a392
FC
790
791Previously C<my $pi := 4;> was exactly equivalent to C<my $pi : = 4;>,
792with the C<:> being treated as the start of an attribute list, ending before
179813a8
FC
793the C<=>. The use of C<:=> to mean C<: => was deprecated in 5.12.0, and is
794now a syntax error. This will allow the future use of C<:=> as a new
795token.
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796
797We find no Perl 5 code on CPAN using this construction, outside the core's
798tests for it, so we believe that this change will have very little impact on
799real-world codebases.
800
801If it is absolutely necessary to have empty attribute lists (for example,
802because of a code generator) then avoid the error by adding a space before
803the C<=>.
804
d1ef1aa8
FC
805=head3 Change in the parsing of identifiers
806
807Characters outside the Unicode "XIDStart" set are no longer allowed at the
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808beginning of an identifier. This means that certain accents and marks
809that normally follow an alphabetic character may no longer be the first
810character of an identifier.
d1ef1aa8 811
61752d82 812=head2 Threads and Processes
5076a392 813
61752d82 814=head3 Directory handles not copied to threads
5076a392 815
61752d82
FC
816On systems other than Windows that do not have
817a C<fchdir> function, newly-created threads no
179813a8 818longer inherit directory handles from their parent threads. Such programs
61752d82 819would usually have crashed anyway [perl #75154].
5076a392 820
61752d82 821=head3 C<close> on shared pipes
5076a392 822
61752d82
FC
823The C<close> function no longer waits for the child process to exit if the
824underlying file descriptor is still in use by another thread, to avoid
179813a8 825deadlocks. It returns true in such cases.
5076a392 826
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FC
827=head3 fork() emulation will not wait for signalled children
828
829On Windows parent processes would not terminate until all forked
830childred had terminated first. However, C<kill('KILL', ...)> is
831inherently unstable on pseudo-processes, and C<kill('TERM', ...)>
179813a8 832might not get delivered if the child is blocked in a system call.
144b6ea2
FC
833
834To avoid the deadlock and still provide a safe mechanism to terminate
835the hosting process, Perl will now no longer wait for children that
836have been sent a SIGTERM signal. It is up to the parent process to
837waitpid() for these children if child clean-up processing must be
179813a8 838allowed to finish. However, it is also the responsibility of the
144b6ea2
FC
839parent then to avoid the deadlock by making sure the child process
840can't be blocked on I/O either.
841
842See L<perlfork> for more information about the fork() emulation on
843Windows.
844
61752d82 845=head2 Configuration
5076a392 846
61752d82 847=head3 Naming fixes in Policy_sh.SH may invalidate Policy.sh
5076a392 848
61752d82
FC
849Several long-standing typos and naming confusions in Policy_sh.SH have
850been fixed, standardizing on the variable names used in config.sh.
5076a392 851
61752d82 852This will change the behavior of Policy.sh if you happen to have been
179813a8 853accidentally relying on its incorrect behavior.
f318e2e6 854
5a1f7719
FC
855=head3 Perl source code is read in text mode on Windows
856
857Perl scripts used to be read in binary mode on Windows for the benefit
858of the ByteLoader module (which is no longer part of core Perl). This
859had the side effect of breaking various operations on the DATA filehandle,
860including seek()/tell(), and even simply reading from DATA after file handles
861have been flushed by a call to system(), backticks, fork() etc.
862
863The default build options for Windows have been changed to read Perl source
864code on Windows in text mode now. Hopefully ByteLoader will be updated on
865CPAN to automatically handle this situation [perl #28106].
866
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867=head1 Deprecations
868
1e463951
FC
869See also L</Deprecated C APIs>.
870
5076a392
FC
871=head2 Omitting a space between a regular expression and subsequent word
872
18139a1b
FC
873Omitting a space between a regular expression operator or
874its modifiers and the following word is deprecated. For
875example, C<< m/foo/sand $bar >> will still be parsed
876as C<< m/foo/s and $bar >> but will issue a warning.
5076a392 877
e683df94
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878=head2 C<\cI<X>>
879
880The backslash-c construct was designed as a way of specifying
881non-printable characters, but there were no restrictions (on ASCII
882platforms) on what the character following the C<c> could be. Now,
883a deprecation warning is raised if that character isn't an ASCII character.
884Also, a deprecation warning is raised for C<"\c{"> (which is the same
885as simply saying C<";">).
886
4528361d
KW
887=head2 C<"\b{"> and C<"\B{">
888
889In regular expressions, a literal C<"{"> immediately following a C<"\b">
890(not in a bracketed character class) or a C<"\B{"> is now deprecated
891to allow for its future use by Perl itself.
892
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893=head2 Deprecation warning added for deprecated-in-core .pl libs
894
895This is a mandatory warning, not obeying -X or lexical warning bits.
896The warning is modelled on that supplied by deprecate.pm for
897deprecated-in-core .pm libraries. It points to the specific CPAN
823d0e46
FC
898distribution that contains the .pl libraries. The CPAN version, of
899course, does not generate the warning.
5076a392
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900
901=head2 List assignment to C<$[>
902
823d0e46
FC
903Assignment to C<$[> was deprecated and started to give warnings in
904Perl version 5.12.0. This version of perl also starts to emit a warning when
905assigning to C<$[> in list context. This fixes an oversight in 5.12.0.
5076a392
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906
907=head2 Use of qw(...) as parentheses
908
909Historically the parser fooled itself into thinking that C<qw(...)> literals
910were always enclosed in parentheses, and as a result you could sometimes omit
911parentheses around them:
912
913 for $x qw(a b c) { ... }
914
915The parser no longer lies to itself in this way. Wrap the list literal in
823d0e46 916parentheses, like this:
5076a392
FC
917
918 for $x (qw(a b c)) { ... }
919
920=head2 C<\N{BELL}> is deprecated
921
922This is because Unicode is using that name for a different character.
923See L</Unicode Version 6.0 is now supported (mostly)> for more
924explanation.
925
926=head2 C<?PATTERN?> is deprecated
927
928C<?PATTERN?> (without the initial m) has been deprecated and now produces
929a warning. This is to allow future use of C<?> in new operators.
930The match-once functionality is still available in the form of C<m?PATTERN?>.
931
5076a392
FC
932=head2 Tie functions on scalars holding typeglobs
933
934Calling a tie function (C<tie>, C<tied>, C<untie>) with a scalar argument
935acts on a file handle if the scalar happens to hold a typeglob.
936
937This is a long-standing bug that will be removed in Perl 5.16, as
938there is currently no way to tie the scalar itself when it holds
939a typeglob, and no way to untie a scalar that has had a typeglob
940assigned to it.
941
823d0e46 942Now there is a deprecation warning whenever a tie
5076a392
FC
943function is used on a handle without an explicit C<*>.
944
18139a1b 945=head2 User-defined case-mapping
5076a392 946
18139a1b
FC
947This feature is being deprecated due to its many issues, as documented in
948L<perlunicode/User-Defined Case Mappings (for serious hackers only)>.
e48f36f0
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949It is planned to remove this feature in Perl 5.16. Instead use the CPAN module
950L<Unicode::Casing>, which provides improved functionality.
823d0e46 951
18139a1b 952=head2 Deprecated modules
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953
954The following modules will be removed from the core distribution in a
955future release, and should be installed from CPAN instead. Distributions
a60ea503 956on CPAN which require these should add them to their prerequisites. The
823d0e46 957core versions of these modules will issue a deprecation warning.
5076a392
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958
959If you ship a packaged version of Perl, either alone or as part of a
960larger system, then you should carefully consider the repercussions of
823d0e46 961core module deprecations. You may want to consider shipping your default
5076a392 962build of Perl with packages for some or all deprecated modules which
823d0e46 963install into C<vendor> or C<site> perl library directories. This will
5076a392
FC
964inhibit the deprecation warnings.
965
966Alternatively, you may want to consider patching F<lib/deprecate.pm>
967to provide deprecation warnings specific to your packaging system
968or distribution of Perl, consistent with how your packaging system
969or distribution manages a staged transition from a release where the
970installation of a single package provides the given functionality, to
971a later release where the system administrator needs to know to install
972multiple packages to get that same functionality.
973
974You can silence these deprecation warnings by installing the modules
975in question from CPAN. To install the latest version of all of them,
976just install C<Task::Deprecations::5_14>.
977
978=over
979
980=item L<Devel::DProf>
981
982We strongly recommend that you install and used L<Devel::NYTProf> in
983preference, as it offers significantly improved profiling and reporting.
984
985=back
986
5076a392
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987=head1 Performance Enhancements
988
54c7bb16 989=head2 "Safe signals" optimisation
df91d470 990
a60ea503 991Signal dispatch has been moved from the runloop into control ops. This
df91d470
FC
992should give a few percent speed increase, and eliminates almost all of
993the speed penalty caused by the introduction of "safe signals" in
a60ea503 9945.8.0. Signals should still be dispatched within the same statement as
df91d470
FC
995they were previously - if this is not the case, or it is possible to
996create uninterruptible loops, this is a bug, and reports are encouraged
997of how to recreate such issues.
998
54c7bb16 999=head2 Optimisation of shift; and pop; calls without arguments
df91d470 1000
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1001Two fewer OPs are used for shift and pop calls with no argument (with
1002implicit C<@_>). This change makes C<shift;> 5% faster than C<shift @_;>
1003on non-threaded perls and 25% faster on threaded.
df91d470 1004
fa232254 1005=head2 Optimisation of regexp engine string comparison work
df91d470 1006
fa232254
FC
1007The foldEQ_utf8 API function for case-insensitive comparison of strings (which
1008is used heavily by the regexp engine) was substantially refactored and
1009optimised - and its documentation much improved as a free bonus gift.
df91d470 1010
fa232254 1011=head2 Regular expression compilation speed-up
df91d470 1012
fa232254
FC
1013Compiling regular expressions has been made faster for the case where upgrading
1014the regex to utf8 is necessary but that isn't known when the compilation begins.
df91d470 1015
fa232254 1016=head2 String appending is 100 times faster
df91d470 1017
fa232254
FC
1018When doing a lot of string appending, perl could end up allocating a lot more
1019memory than needed in a very inefficient way, if perl was configured to use the
1020system's C<malloc> implementation instead of its own.
1021
1022C<sv_grow>, which is what's being used to allocate more memory if necessary
1023when appending to a string, has now been taught how to round up the memory
1024it requests to a certain geometric progression, making it much faster on
1025certain platforms and configurations. On Win32, it's now about 100 times
1026faster.
1027
1028=head2 Eliminate C<PL_*> accessor functions under ithreads
1029
1030When C<MULTIPLICITY> was first developed, and interpreter state moved into
1031an interpreter struct, thread and interpreter local C<PL_*> variables were
1032defined as macros that called accessor functions, returning the address of
1033the value, outside of the perl core. The intent was to allow members
1034within the interpreter struct to change size without breaking binary
1035compatibility, so that bug fixes could be merged to a maintenance branch
1036that necessitated such a size change.
1037
1038However, some non-core code defines C<PERL_CORE>, sometimes intentionally
1039to bypass this mechanism for speed reasons, sometimes for other reasons but
1040with the inadvertent side effect of bypassing this mechanism. As some of
1041this code is widespread in production use, the result is that the core
1042I<can't> change the size of members of the interpreter struct, as it will
1043break such modules compiled against a previous release on that maintenance
1044branch. The upshot is that this mechanism is redundant, and well-behaved
1045code is penalised by it. Hence it can and should be removed (and has
1046been).
1047
1048=head2 Freeing weak references
1049
1050When an object has many weak references to it, freeing that object
1051can under some some circumstances take O(N^2) time to free (where N is the
a60ea503 1052number of references). The number of circumstances has been reduced
fa232254
FC
1053[perl #75254]
1054
1055=head2 Lexical array and hash assignments
1056
1057An earlier optimisation to speed up C<my @array = ...> and
1058C<my %hash = ...> assignments caused a bug and was disabled in Perl 5.12.0.
1059
1060Now we have found another way to speed up these assignments [perl #82110].
df91d470 1061
111b6aa7 1062=head2 C<@_> uses less memory
df91d470 1063
111b6aa7
FC
1064Previously, C<@_> was allocated for every subroutine at compile time with
1065enough space for four entries. Now this allocation is done on demand when
1066the subroutine is called [perl #72416].
5076a392 1067
5076a392
FC
1068=head2 Size optimisations to SV and HV structures
1069
1070xhv_fill has been eliminated from struct xpvhv, saving 1 IV per hash and
a60ea503 1071on some systems will cause struct xpvhv to become cache-aligned. To avoid
5076a392
FC
1072this memory saving causing a slowdown elsewhere, boolean use of HvFILL
1073now calls HvTOTALKEYS instead (which is equivalent) - so while the fill
111b6aa7
FC
1074data when actually required are now calculated on demand, the cases when
1075this needs to be done should be few and far between.
5076a392 1076
111b6aa7
FC
1077The order of structure elements in SV bodies has changed. Effectively,
1078the NV slot has swapped location with STASH and MAGIC. As all access to
1079SV members is via macros, this should be completely transparent. This
5076a392
FC
1080change allows the space saving for PVHVs documented above, and may reduce
1081the memory allocation needed for PVIVs on some architectures.
1082
fa232254
FC
1083C<XPV>, C<XPVIV>, and C<XPVNV> now only allocate the parts of the C<SV> body
1084they actually use, saving some space.
5076a392 1085
fa232254
FC
1086Scalars containing regular expressions now only allocate the part of the C<SV>
1087body they actually use, saving some space.
5076a392
FC
1088
1089=head2 Memory consumption improvements to Exporter
1090
1091The @EXPORT_FAIL AV is no longer created unless required, hence neither is
111b6aa7
FC
1092the typeglob backing it. This saves about 200 bytes for every package that
1093uses Exporter but doesn't use this functionality.
5076a392 1094
111b6aa7 1095=head2 Memory savings for weak references
5076a392
FC
1096
1097For weak references, the common case of just a single weak reference per
a60ea503
FC
1098referent has been optimised to reduce the
1099storage required. In this case it
111b6aa7 1100saves the equivalent of one small Perl array per referent.
5076a392 1101
111b6aa7 1102=head2 C<%+> and C<%-> use less memory
5076a392
FC
1103
1104The bulk of the C<Tie::Hash::NamedCapture> module used to be in the perl
111b6aa7 1105core. It has now been moved to an XS module, to reduce the overhead for
5076a392
FC
1106programs that do not use C<%+> or C<%->.
1107
fa232254 1108=head2 Multiple small improvements to threads
5076a392 1109
fa232254
FC
1110The internal structures of threading now make fewer API calls and fewer
1111allocations, resulting in noticeably smaller object code. Additionally,
1112many thread context checks have been deferred so that they're only done
1113when required (although this is only possible for non-debugging builds).
5076a392 1114
fa232254 1115=head2 Adjacent pairs of nextstate opcodes are now optimized away
5076a392 1116
fa232254 1117Previously, in code such as
5076a392 1118
fa232254 1119 use constant DEBUG => 0;
5076a392 1120
fa232254
FC
1121 sub GAK {
1122 warn if DEBUG;
1123 print "stuff\n";
1124 }
5076a392 1125
fa232254
FC
1126the ops for C<warn if DEBUG;> would be folded to a C<null> op (C<ex-const>), but
1127the C<nextstate> op would remain, resulting in a runtime op dispatch of
1128C<nextstate>, C<nextstate>, ....
5076a392 1129
fa232254
FC
1130The execution of a sequence of C<nextstate> ops is indistinguishable from just
1131the last C<nextstate> op so the peephole optimizer now eliminates the first of
1132a pair of C<nextstate> ops, except where the first carries a label, since labels
1133must not be eliminated by the optimizer and label usage isn't conclusively known
1134at compile time.
5076a392
FC
1135
1136=head1 Modules and Pragmata
1137
1138=head2 New Modules and Pragmata
1139
1140=over 4
1141
1142=item *
1143
1144C<CPAN::Meta::YAML> 0.003 has been added as a dual-life module. It supports a
1145subset of YAML sufficient for reading and writing META.yml and MYMETA.yml files
1146included with CPAN distributions or generated by the module installation
a60ea503 1147toolchain. It should not be used for any other general YAML parsing or
5076a392
FC
1148generation task.
1149
1150=item *
1151
a60ea503 1152C<CPAN::Meta> version 2.110440 has been added as a dual-life module. It
5076a392
FC
1153provides a standard library to read, interpret and write CPAN distribution
1154metadata files (e.g. META.json and META.yml) which describes a
1155distribution, its contents, and the requirements for building it and
a60ea503 1156installing it. The latest CPAN distribution metadata specification is
5076a392
FC
1157included as C<CPAN::Meta::Spec> and notes on changes in the specification
1158over time are given in C<CPAN::Meta::History>.
1159
1160=item *
1161
c0331f42 1162C<HTTP::Tiny> 0.012 has been added as a dual-life module. It is a very
5076a392
FC
1163small, simple HTTP/1.1 client designed for simple GET requests and file
1164mirroring. It has has been added to enable CPAN.pm and CPANPLUS to
1165"bootstrap" HTTP access to CPAN using pure Perl without relying on external
1166binaries like F<curl> or F<wget>.
1167
1168=item *
1169
1170C<JSON::PP> 2.27105 has been added as a dual-life module, for the sake of
1171reading F<META.json> files in CPAN distributions.
1172
1173=item *
1174
21ef4e45 1175C<Module::Metadata> 1.000004 has been added as a dual-life module. It gathers
5076a392
FC
1176package and POD information from Perl module files. It is a standalone module
1177based on Module::Build::ModuleInfo for use by other module installation
1178toolchain components. Module::Build::ModuleInfo has been deprecated in
1179favor of this module instead.
1180
1181=item *
1182
1183C<Perl::OSType> 1.002 has been added as a dual-life module. It maps Perl
1184operating system names (e.g. 'dragonfly' or 'MSWin32') to more generic types
1185with standardized names (e.g. "Unix" or "Windows"). It has been refactored
1186out of Module::Build and ExtUtils::CBuilder and consolidates such mappings into
1187a single location for easier maintenance.
1188
1189=item *
1190
1191The following modules were added by the C<Unicode::Collate>
a60ea503 1192upgrade. See below for details.
5076a392
FC
1193
1194C<Unicode::Collate::CJK::Big5>
1195
1196C<Unicode::Collate::CJK::GB2312>
1197
1198C<Unicode::Collate::CJK::JISX0208>
1199
1200C<Unicode::Collate::CJK::Korean>
1201
1202C<Unicode::Collate::CJK::Pinyin>
1203
1204C<Unicode::Collate::CJK::Stroke>
1205
1206=item *
1207
1208C<Version::Requirements> version 0.101020 has been added as a dual-life
1209module. It provides a standard library to model and manipulates module
1210prerequisites and version constraints as defined in the L<CPAN::Meta::Spec>.
1211
1212=back
1213
a5794e94 1214=head2 Updated Modules and Pragma
5076a392
FC
1215
1216=over 4
1217
1218=item *
1219
81a53be2
FR
1220C<attributes> has been upgraded from version 0.12 to 0.14.
1221
1222=item *
1223
5076a392
FC
1224C<Archive::Extract> has been upgraded from version 0.38 to 0.48.
1225
1226Updates since 0.38 include: a safe print method that guards
1227Archive::Extract from changes to $\; a fix to the tests when run in core
1984204c
FC
1228perl; support for TZ files; a modification for the lzma
1229logic to favour IO::Uncompress::Unlzma; and a fix
1230for an issue with NetBSD-current and its new unzip
5076a392
FC
1231executable.
1232
1233=item *
1234
1235C<Archive::Tar> has been upgraded from version 1.54 to 1.76.
1236
1984204c
FC
1237Important changes since 1.54 include the following:
1238
1239=over
1240
1241=item *
1242
1243Compatibility with busybox implementations of tar
1244
1245=item *
1246
1247A fix so that C<write()> and C<create_archive()>
1248close only handles they opened
1249
1250=item *
1251
1252A bug was fixed regarding the exit code of extract_archive.
5076a392 1253
1984204c
FC
1254=item *
1255
4f978a3b 1256The C<ptar> utility has a new option to allow safe
5076a392
FC
1257creation of tarballs without world-writable files on Windows, allowing those
1258archives to be uploaded to CPAN.
1259
1984204c
FC
1260=item *
1261
1262A new ptargrep utility for using regular expressions against
5076a392
FC
1263the contents of files in a tar archive.
1264
1984204c
FC
1265=item *
1266
1267Pax extended headers are now skipped.
1268
1269=back
5076a392
FC
1270
1271=item *
1272
fcd5df6d
FR
1273C<Attribute::Handlers> has been upgraded from version 0.87 to 0.89.
1274
1275=item *
1276
3f5a47e4
FR
1277C<autodie> has been upgraded from version 2.06_01 to 2.1001.
1278
1279=item *
1280
578e7c9d
FR
1281C<AutoLoader> has been upgraded from version 5.70 to 5.71.
1282
1283=item *
1284
a13baafd 1285C<B> has been upgraded from version 1.23 to 1.29.
5076a392
FC
1286
1287It no longer crashes when taking apart a C<y///> containing characters
1288outside the octet range or compiled in a C<use utf8> scope.
1289
1290The size of the shared object has been reduced by about 40%, with no
1291reduction in functionality.
1292
1293=item *
1294
4a75fbf5 1295C<B::Concise> has been upgraded from version 0.78 to 0.83.
5076a392
FC
1296
1297B::Concise marks rv2sv, rv2av and rv2hv ops with the new OPpDEREF flag
1298as "DREFed".
1299
1300It no longer produces mangled output with the C<-tree> option
1301[perl #80632].
1302
1303=item *
1304
6bb8c1e3
FR
1305C<B::Debug> has been upgraded from version 1.12 to 1.16.
1306
1307=item *
1308
c67a4e29 1309C<B::Deparse> has been upgraded from version 0.96 to 1.03.
5076a392 1310
1984204c 1311The deparsing of a nextstate op has changed when it has both a
5076a392
FC
1312change of package (relative to the previous nextstate), or a change of
1313C<%^H> or other state, and a label. Previously the label was emitted
cdc10f43 1314first, but now the label is emitted last (5.12.1).
5076a392 1315
5a553547
FC
1316The C<no 5.13.2> or similar form is now correctly handled by B::Deparse
1317(5.12.3).
5076a392
FC
1318
1319B::Deparse now properly handles the code that applies a conditional
1320pattern match against implicit C<$_> as it was fixed in [perl #20444].
1321
1984204c
FC
1322Deparsing of C<our> followed by a variable with funny characters
1323(as permitted under the C<utf8> pragma) has also been fixed [perl #33752].
5076a392
FC
1324
1325=item *
1326
d97c5d3b
FR
1327C<B::Lint> has been upgraded from version 1.11_01 to 1.13.
1328
1329=item *
1330
5aef2c44
FR
1331C<base> has been upgraded from version 2.15 to 2.16.
1332
1333=item *
1334
876607aa
FR
1335C<Benchmark> has been upgraded from version 1.11 to 1.12.
1336
1337=item *
1338
0f3a8103 1339C<bignum> has been upgraded from version 0.23 to 0.27.
e539ae69
FR
1340
1341=item *
1342
c74c1fa8 1343C<Carp> has been upgraded from version 1.15 to 1.20.
5076a392
FC
1344
1345L<Carp> now detects incomplete L<caller()|perlfunc/"caller EXPR"> overrides and
d430b8e7
FC
1346avoids using bogus C<@DB::args>. To provide backtraces,
1347Carp relies on particular behaviour of the C<caller>
1348built-in. Carp now detects if other code has
5076a392 1349overridden this with an incomplete implementation, and modifies its backtrace
d430b8e7
FC
1350accordingly. Previously incomplete overrides would cause incorrect values
1351in backtraces (best case), or obscure fatal errors (worst case).
5076a392
FC
1352
1353This fixes certain cases of C<Bizarre copy of ARRAY> caused by modules
d430b8e7 1354overriding C<caller()> incorrectly (5.12.2).
5076a392 1355
1984204c 1356It now also avoids using regular expressions that cause perl to
5076a392
FC
1357load its Unicode tables, in order to avoid the 'BEGIN not safe after
1358errors' error that will ensue if there has been a syntax error
1359[perl #82854].
1360
1361=item *
1362
9eb7ad55 1363C<CGI> has been upgraded from version 3.48 to 3.52.
5076a392
FC
1364
1365This provides the following security fixes: the MIME boundary in
1984204c
FC
1366multipart_init is now random and the handling of
1367newlines embedded in header values has been improved.
5076a392
FC
1368
1369=item *
1370
5076a392
FC
1371C<Compress::Raw::Bzip2> has been upgraded from version 2.024 to 2.033.
1372
1984204c 1373It has been updated to use bzip2 1.0.6.
5076a392
FC
1374
1375=item *
1376
51090521
FR
1377C<Compress::Raw::Zlib> has been upgraded from version 2.024 to 2.033.
1378
1379=item *
1380
f75b7efc 1381C<CPAN> has been upgraded from version 1.94_56 to 1.9600.
1984204c
FC
1382
1383Major highlights:
5076a392
FC
1384
1385=over 4
1386
1984204c 1387=item * much less configuration dialog hassle
5076a392 1388
1984204c 1389=item * support for META/MYMETA.json
5076a392 1390
1984204c 1391=item * support for local::lib
5076a392 1392
1984204c 1393=item * support for HTTP::Tiny to reduce the dependency on ftp sites
5076a392 1394
1984204c 1395=item * automatic mirror selection
5076a392 1396
1984204c 1397=item * iron out all known bugs in configure_requires
5076a392 1398
1984204c
FC
1399=item * support for distributions compressed with bzip2
1400
1401=item * allow Foo/Bar.pm on the commandline to mean Foo::Bar
1402
1403=back
5076a392
FC
1404
1405=item *
1406
d430b8e7
FC
1407C<CPANPLUS> has been upgraded from version 0.90 to 0.9103.
1408
1409A change to F<cpanp-run-perl>
1410resolves L<RT #55964|http://rt.cpan.org/Public/Bug/Display.html?id=55964>
1411and L<RT #57106|http://rt.cpan.org/Public/Bug/Display.html?id=57106>, both
1412of which related to failures to install distributions that use
1413C<Module::Install::DSL> (5.12.2).
5076a392 1414
1984204c
FC
1415A dependency on Config was not recognised as a
1416core module dependency. This has been fixed.
5076a392 1417
1984204c 1418CPANPLUS now includes support for META.json and MYMETA.json.
5076a392
FC
1419
1420=item *
1421
4467e8f7
FR
1422C<CPANPLUS::Dist::Build> has been upgraded from version 0.46 to 0.54.
1423
1424=item *
1425
5076a392
FC
1426C<Data::Dumper> has been upgraded from version 2.125 to 2.130_02.
1427
4ed2cea4
FC
1428The indentation used to be off when C<$Data::Dumper::Terse> was set. This
1429has been fixed [perl #73604].
1430
1984204c
FC
1431This upgrade also fixes a crash when using custom sort functions that might
1432cause the stack to change [perl #74170].
5076a392
FC
1433
1434C<Dumpxs> no longer crashes with globs returned by C<*$io_ref>
1435[perl #72332].
1436
1437=item *
1438
549d34f5
FR
1439C<DB_File> has been upgraded from version 1.820 to 1.821.
1440
1441=item *
1442
851dbda2
FR
1443C<DBM_Filter> has been upgraded from version 0.03 to 0.04.
1444
1445=item *
1446
5076a392
FC
1447C<Devel::DProf> has been upgraded from version 20080331.00 to 20110228.00.
1448
1449Merely loading C<Devel::DProf> now no longer triggers profiling to start.
1450C<use Devel::DProf> and C<perl -d:DProf ...> still behave as before and start
1451the profiler.
1452
1453NOTE: C<Devel::DProf> is deprecated and will be removed from a future
1984204c 1454version of Perl. We strongly recommend that you install and use
5076a392
FC
1455L<Devel::NYTProf> instead, as it offers significantly improved
1456profiling and reporting.
1457
1458=item *
1459
868625d2
FR
1460C<Devel::Peek> has been upgraded from version 1.04 to 1.07.
1461
1462=item *
1463
66899ca3
FR
1464C<Devel::SelfStubber> has been upgraded from version 1.03 to 1.05.
1465
1466=item *
1467
5076a392
FC
1468C<diagnostics> has been upgraded from version 1.19 to 1.22.
1469
1470It now renders pod links slightly better, and has been taught to find
1471descriptions for messages that share their descriptions with other
1472messages.
1473
1474=item *
1475
1476C<Digest::MD5> has been upgraded from version 2.39 to 2.51.
1477
1478It is now safe to use this module in combination with threads.
1479
1480=item *
1481
1482C<Digest::SHA> has been upgraded from version 5.47 to 5.61.
1483
1484C<shasum> now more closely mimics C<sha1sum>/C<md5sum>.
1485
1486C<Addfile> accepts all POSIX filenames.
1487
1984204c
FC
1488New SHA-512/224 and SHA-512/256 transforms (ref. NIST Draft FIPS 180-4
1489[February 2011])
5076a392
FC
1490
1491=item *
1492
88410521
FR
1493C<DirHandle> has been upgraded from version 1.03 to 1.04.
1494
1495=item *
1496
e53cbaa3
FR
1497C<Dumpvalue> has been upgraded from version 1.13 to 1.16.
1498
1499=item *
1500
31e8b85a 1501C<DynaLoader> has been upgraded from version 1.10 to 1.13.
5076a392
FC
1502
1503It fixes a buffer overflow when passed a very long file name.
1504
1505It no longer inherits from AutoLoader; hence it no longer
1506produces weird error messages for unsuccessful method calls on classes that
1507inherit from DynaLoader [perl #84358].
1508
1509=item *
1510
1511C<Encode> has been upgraded from version 2.39 to 2.42.
1512
1513Now, all 66 Unicode non-characters are treated the same way U+FFFF has
1984204c
FC
1514always been treated; in cases when it was disallowed, all 66 are
1515disallowed; in those cases where it warned, all 66 warn.
5076a392
FC
1516
1517=item *
1518
68f90ac3
FR
1519C<Env> has been upgraded from version 1.01 to 1.02.
1520
1521=item *
1522
5076a392
FC
1523C<Errno> has been upgraded from version 1.11 to 1.13.
1524
1525The implementation of C<Errno> has been refactored to use about 55% less memory.
5076a392
FC
1526
1527On some platforms with unusual header files, like Win32/gcc using mingw64
1528headers, some constants which weren't actually error numbers have been exposed
1529by C<Errno>. This has been fixed [perl #77416].
1530
1531=item *
1532
1533C<Exporter> has been upgraded from version 5.64_01 to 5.64_03.
1534
1535Exporter no longer overrides C<$SIG{__WARN__}> [perl #74472]
1536
1537=item *
1538
7287d036 1539C<ExtUtils::CBuilder> has been upgraded from version 0.27 to 0.280203.
25fe7f8f
FR
1540
1541=item *
1542
2292e71e
FR
1543C<ExtUtils::Command> has been upgraded from version 1.16 to 1.17.
1544
1545=item *
1546
5076a392
FC
1547C<ExtUtils::Constant> has been upgraded from 0.22 to 0.23.
1548
1549The C<AUTOLOAD> helper code generated by C<ExtUtils::Constant::ProxySubs>
1550can now C<croak> for missing constants, or generate a complete C<AUTOLOAD>
1984204c
FC
1551subroutine in XS, allowing simplification of many modules that use it
1552(C<Fcntl>, C<File::Glob>, C<GDBM_File>, C<I18N::Langinfo>, C<POSIX>,
1553C<Socket>).
5076a392
FC
1554
1555C<ExtUtils::Constant::ProxySubs> can now optionally push the names of all
1984204c 1556constants onto the package's C<@EXPORT_OK>.
5076a392
FC
1557
1558=item *
1559
588c5853
FR
1560C<ExtUtils::Install> has been upgraded from version 1.55 to 1.56.
1561
1562=item *
1563
5418ffb3
FR
1564C<ExtUtils::MakeMaker> has been upgraded from version 6.56 to 6.57_05.
1565
1566=item *
1567
f40ab45f
FR
1568C<ExtUtils::Manifest> has been upgraded from version 1.57 to 1.58.
1569
1570=item *
1571
10fb15d2 1572C<ExtUtils::ParseXS> has been upgraded from version 2.21 to 2.2210.
b7064dd7
FR
1573
1574=item *
1575
8b87be80 1576C<Fcntl> has been upgraded from version 1.06 to 1.11.
26f7fa64
FR
1577
1578=item *
1579
da25e274 1580C<File::Basename> has been upgraded from version 2.78 to 2.82.
8b87be80
FR
1581
1582=item *
1583
05102622
FR
1584C<File::CheckTree> has been upgraded from version 4.4 to 4.41.
1585
1586=item *
1587
65d78858
FR
1588C<File::Copy> has been upgraded from version 2.17 to 2.21.
1589
1590=item *
1591
e12786fa 1592C<File::DosGlob> has been upgraded from version 1.01 to 1.04.
5076a392
FC
1593
1594It allows patterns containing literal parentheses (they no longer need to
1984204c
FC
1595be escaped). On Windows, it no longer
1596adds an extra F<./> to the file names
5076a392
FC
1597returned when the pattern is a relative glob with a drive specification,
1598like F<c:*.pl> [perl #71712].
1599
1600=item *
1601
1602C<File::Fetch> has been upgraded from version 0.24 to 0.32.
1603
1604C<HTTP::Lite> is now supported for 'http' scheme.
1605
1606The C<fetch> utility is supported on FreeBSD, NetBSD and
1607Dragonfly BSD for the C<http> and C<ftp> schemes.
1608
1609=item *
1610
23f2cbb1 1611C<File::Find> has been upgraded from version 1.15 to 1.19.
5076a392 1612
1984204c 1613It improves handling of backslashes on Windows, so that paths like
5076a392
FC
1614F<c:\dir\/file> are no longer generated [perl #71710].
1615
1616=item *
1617
0ae9f678
FR
1618C<File::Glob> has been upgraded from version 1.07 to 1.12.
1619
1620=item *
1621
d430b8e7
FC
1622C<File::Spec> has been upgraded from version 3.31 to 3.33.
1623
1624Several portability fixes were made in C<File::Spec::VMS>: a colon is now
1625recognized as a delimiter in native filespecs; caret-escaped delimiters are
1626recognized for better handling of extended filespecs; C<catpath()> returns
1627an empty directory rather than the current directory if the input directory
1628name is empty; C<abs2rel()> properly handles Unix-style input (5.12.2).
1629
1630=item *
1631
46ba0657 1632C<File::stat> has been upgraded from 1.02 to 1.05.
5076a392
FC
1633
1634The C<-x> and C<-X> file test operators now work correctly under the root
1635user.
1636
1637=item *
1638
b7edcc3c
FR
1639C<Filter::Simple> has been upgraded from version 0.84 to 0.86.
1640
1641=item *
1642
dc6857fd 1643C<GDBM_File> has been upgraded from 1.10 to 1.14.
5076a392
FC
1644
1645This fixes a memory leak when DBM filters are used.
1646
1647=item *
1648
6e107b45 1649C<Hash::Util> has been upgraded from 0.07 to 0.11.
5076a392 1650
1984204c
FC
1651Hash::Util no longer emits spurious "uninitialized" warnings when
1652recursively locking hashes that have undefined values [perl #74280].
5076a392
FC
1653
1654=item *
1655
89ce9b34
FR
1656C<Hash::Util::FieldHash> has been upgraded from version 1.04 to 1.09.
1657
1658=item *
1659
eec33fe6
FR
1660C<I18N::Collate> has been upgraded from version 1.01 to 1.02.
1661
1662=item *
1663
ad5f8f47 1664C<I18N::Langinfo> has been upgraded from version 0.03 to 0.08.
5076a392
FC
1665
1666C<langinfo()> now defaults to using C<$_> if there is no argument given, just
5334145a 1667as the documentation has always claimed.
5076a392
FC
1668
1669=item *
1670
c41635f7
FR
1671C<I18N::LangTags> has been upgraded from version 0.35 to 0.35_01.
1672
1673=item *
1674
98a6a4ff
FR
1675C<if> has been upgraded from version 0.05 to 0.0601.
1676
1677=item *
1678
f6ff7fb6
FR
1679C<IO> has been upgraded from version 1.25_02 to 1.25_04.
1680
582bf58c
FR
1681This version of C<IO> includes a new C<IO::Select>, which now allows IO::Handle
1682objects (and objects in derived classes) to be removed from an IO::Select set
1683even if the underlying file descriptor is closed or invalid.
5076a392
FC
1684
1685=item *
1686
d07561d3 1687C<IPC::Cmd> has been upgraded from version 0.54 to 0.70.
5076a392 1688
1984204c
FC
1689Resolves an issue with splitting Win32 command lines. An argument
1690consisting of the single character "0" used to be omitted (CPAN RT #62961).
5076a392
FC
1691
1692=item *
1693
3f16e4eb 1694C<IPC::Open3> has been upgraded from 1.05 to 1.09.
5076a392 1695
4ed2cea4
FC
1696C<open3> now produces an error if the C<exec> call fails, allowing this
1697condition to be distinguished from a child process that exited with a
1698non-zero status [perl #72016].
1699
5076a392
FC
1700The internal C<xclose> routine now knows how to handle file descriptors, as
1701documented, so duplicating STDIN in a child process using its file
1702descriptor now works [perl #76474].
1703
1704=item *
1705
c8b41807
FR
1706C<IPC::SysV> has been upgraded from version 2.01 to 2.03.
1707
1708=item *
1709
ef79f038
FR
1710C<lib> has been upgraded from version 0.62 to 0.63.
1711
1712=item *
1713
5b1884f4 1714C<Locale::Maketext> has been upgraded from version 1.14 to 1.19.
5076a392 1715
1984204c 1716Locale::Maketext now supports external caches.
5076a392 1717
1984204c
FC
1718This upgrade also fixes an infinite loop in
1719C<Locale::Maketext::Guts::_compile()> when
5076a392
FC
1720working with tainted values (CPAN RT #40727).
1721
1984204c 1722C<< ->maketext >> calls will now back up and restore C<$@> so that error
5076a392
FC
1723messages are not suppressed (CPAN RT #34182).
1724
1725=item *
1726
3811bd2b
FR
1727C<Log::Message> has been upgraded from version 0.02 to 0.04.
1728
1729=item *
1730
8eb65377
FR
1731C<Log::Message::Simple> has been upgraded from version 0.06 to 0.08.
1732
1733=item *
1734
5076a392
FC
1735C<Math::BigInt> has been upgraded from version 1.89_01 to 1.994.
1736
1737This fixes, among other things, incorrect results when computing binomial
1738coefficients [perl #77640].
1739
1984204c 1740It also prevents C<sqrt($int)> from crashing under C<use bigrat;>
5076a392
FC
1741[perl #73534].
1742
1743=item *
1744
846c1cec
FR
1745C<Math::BigInt::FastCalc> has been upgraded from version 0.19 to 0.28.
1746
1747=item *
1748
fce4aef3
FR
1749C<Math::BigRat> has been upgraded from version 0.24 to 0.26_02.
1750
1751=item *
1752
12e26027
FR
1753C<Memoize> has been upgraded from version 1.01_03 to 1.02.
1754
1755=item *
1756
5076a392
FC
1757C<MIME::Base64> has been upgraded from 3.08 to 3.13.
1758
1759Includes new functions to calculate the length of encoded and decoded
1760base64 strings.
1761
1762Now provides C<encode_base64url> and C<decode_base64url> functions to process
1763the base64 scheme for "URL applications".
1764
1765=item *
1766
1767C<Module::Build> has been upgraded from version 0.3603 to 0.3800.
1768
1769A notable change is the deprecation of several modules.
1770Module::Build::Version has been deprecated and Module::Build now relies
1771directly upon L<version>. Module::Build::ModuleInfo has been deprecated in
1772favor of a standalone copy of it called L<Module::Metadata>.
1773Module::Build::YAML has been deprecated in favor of L<CPAN::Meta::YAML>.
1774
1775Module::Build now also generates META.json and MYMETA.json files
1776in accordance with version 2 of the CPAN distribution metadata specification,
1777L<CPAN::Meta::Spec>. The older format META.yml and MYMETA.yml files are
1778still generated, as well.
1779
1780=item *
1781
7259fe26 1782C<Module::CoreList> has been upgraded from version 2.29 to 2.47.
5076a392
FC
1783
1784Besides listing the updated core modules of this release, it also stops listing
1984204c 1785the C<Filespec> module. That module never existed in core. The scripts
5076a392 1786generating C<Module::CoreList> confused it with C<VMS::Filespec>, which actually
1984204c 1787is a core module as of perl 5.8.7.
5076a392
FC
1788
1789=item *
1790
193af05b
FR
1791C<Module::Load> has been upgraded from version 0.16 to 0.18.
1792
1793=item *
1794
5b3a054f
FR
1795C<Module::Load::Conditional> has been upgraded from version 0.34 to 0.44.
1796
1797=item *
1798
01835e3a
FR
1799C<mro> has been upgraded from version 1.02 to 1.07.
1800
1801=item *
1802
bfe7bf96 1803C<NDBM_File> has been upgraded from version 1.08 to 1.12.
4f978a3b
FR
1804
1805This fixes a memory leak when DBM filters are used.
1806
1807=item *
1808
d0aa5c91
FR
1809C<Net::Ping> has been upgraded from version 2.36 to 2.38.
1810
1811=item *
1812
d44b8a8c
FR
1813C<NEXT> has been upgraded from version 0.64 to 0.65.
1814
1815=item *
1816
678d4fd4
FR
1817C<Object::Accessor> has been upgraded from version 0.36 to 0.38.
1818
1819=item *
1820
34188656 1821C<ODBM_File> have been upgraded from version 1.07 to 1.10.
5076a392
FC
1822
1823This fixes a memory leak when DBM filters are used.
1824
1825=item *
1826
4c69840c
FR
1827C<Opcode> has been upgraded from version 1.15 to 1.18.
1828
1829=item *
1830
f4c5ae54 1831C<overload> has been upgraded from 1.10 to 1.13.
5076a392
FC
1832
1833C<overload::Method> can now handle subroutines that are themselves blessed
1834into overloaded classes [perl #71998].
1835
5076a392
FC
1836The documentation has greatly improved. See L</Documentation> below.
1837
1838=item *
1839
f84c796e
FR
1840C<Params::Check> has been upgraded from version 0.26 to 0.28.
1841
1842=item *
1843
550ee92b
FR
1844C<parent> has been upgraded from version 0.223 to 0.225.
1845
1846=item *
1847
5076a392
FC
1848C<Parse::CPAN::Meta> has been upgraded from version 1.40 to 1.4401.
1849
1984204c 1850The latest Parse::CPAN::Meta can now read YAML and JSON files using
5076a392
FC
1851L<CPAN::Meta::YAML> and L<JSON::PP>, which are now part of the Perl core.
1852
1853=item *
1854
e981cf86
FR
1855C<PerlIO::encoding> has been upgraded from version 0.12 to 0.14.
1856
1857=item *
1858
5076a392
FC
1859C<PerlIO::scalar> has been upgraded from 0.07 to 0.11.
1860
1861A C<read> after a C<seek> beyond the end of the string no longer thinks it
1862has data to read [perl #78716].
1863
1864=item *
1865
776f733b
FR
1866C<PerlIO::via> has been upgraded from version 0.09 to 0.11.
1867
1868=item *
1869
cb1db9bd 1870C<Pod::Html> has been upgraded from version 1.09 to 1.11.
ae9456cc
FR
1871
1872=item *
1873
be3c8498
FR
1874C<Pod::LaTeX> has been upgraded from version 0.58 to 0.59.
1875
1876=item *
1877
fd8a2e89
FR
1878C<Pod::Perldoc> has been upgraded from version 3.15_02 to 3.15_03.
1879
1880=item *
1881
5bcb6583
FR
1882C<Pod::Simple> has been upgraded from version 3.13 to 3.16.
1883
1884=item *
1885
abb8c779 1886C<POSIX> has been upgraded from 1.19 to 1.24.
5076a392
FC
1887
1888It now includes constants for POSIX signal constants.
1889
1890=item *
1891
1984204c 1892C<re> has been upgraded from version 0.11 to 0.17.
5076a392
FC
1893
1894New C<use re "/flags"> pragma
1895
5076a392 1896The C<regmust> function used to crash when called on a regular expression
1984204c 1897belonging to a pluggable engine. Now it croaks instead.
5076a392
FC
1898
1899C<regmust> no longer leaks memory.
1900
1901=item *
1902
1903C<Safe> has been upgraded from version 2.25 to 2.29.
1904
cdc10f43
FC
1905Coderefs returned by C<reval()> and C<rdo()> are now wrapped via
1906C<wrap_code_refs> (5.12.1).
1907
5076a392
FC
1908This fixes a possible infinite loop when looking for coderefs.
1909
cdc10f43 1910It adds several version::vxs::* routines to the default share.
5076a392
FC
1911
1912=item *
1913
2c19fa42
FR
1914C<SDBM_File> has been upgraded from version 1.06 to 1.09.
1915
1916=item *
1917
5076a392
FC
1918C<SelfLoader> has been upgraded from 1.17 to 1.18.
1919
1920It now works in taint mode [perl #72062].
1921
1922=item *
1923
1924C<sigtrap> has been upgraded from version 1.04 to 1.05.
1925
1926It no longer tries to modify read-only arguments when generating a
1927backtrace [perl #72340].
1928
1929=item *
1930
1984204c 1931C<Socket> has been upgraded from version 1.87 to 1.94.
5076a392 1932
1984204c 1933See L</IPv6 support>, above.
5076a392
FC
1934
1935=item *
1936
1937C<Storable> has been upgraded from version 2.22 to 2.27.
1938
1939Includes performance improvement for overloaded classes.
1940
5076a392 1941This adds support for serialising code references that contain UTF-8 strings
1984204c
FC
1942correctly. The Storable minor version
1943number changed as a result, meaning that
5076a392
FC
1944Storable users who set C<$Storable::accept_future_minor> to a C<FALSE> value
1945will see errors (see L<Storable/FORWARD COMPATIBILITY> for more details).
1946
1947Freezing no longer gets confused if the Perl stack gets reallocated
1948during freezing [perl #80074].
1949
1950=item *
1951
648c3d7d
FR
1952C<Sys::Hostname> has been upgraded from version 1.11 to 1.16.
1953
1954=item *
1955
90c6e78f
FR
1956C<Term::ANSIColor> has been upgraded from version 2.02 to 3.00.
1957
1958=item *
1959
d9f2f059
FR
1960C<Term::UI> has been upgraded from version 0.20 to 0.26.
1961
1962=item *
1963
80ebb519
FR
1964C<Test::Harness> has been upgraded from version 3.17 to 3.23.
1965
1966=item *
1967
5076a392
FC
1968C<Test::Simple> has been upgraded from version 0.94 to 0.98.
1969
1970Among many other things, subtests without a C<plan> or C<no_plan> now have an
1971implicit C<done_testing()> added to them.
1972
1973=item *
1974
5076a392
FC
1975C<Thread::Semaphore> has been upgraded from version 2.09 to 2.12.
1976
1984204c
FC
1977It provides two new methods that give more control over the decrementing of
1978semaphores: C<down_nb> and C<down_force>.
5076a392
FC
1979
1980=item *
1981
f0d895e1
FR
1982C<Thread::Queue> has been upgraded from version 2.11 to 2.12.
1983
1984=item *
1985
1a6b954e
FR
1986C<threads> has been upgraded from version 1.75 to 1.83.
1987
1988=item *
1989
55816daa
FR
1990C<threads::shared> has been upgraded from version 1.32 to 1.36.
1991
1992=item *
1993
5076a392
FC
1994C<Tie::Hash> has been upgraded from version 1.03 to 1.04.
1995
1996Calling C<< Tie::Hash-E<gt>TIEHASH() >> used to loop forever. Now it C<croak>s.
1997
1998=item *
1999
f2adc546
FR
2000C<Tie::Hash::NamedCapture> has been upgraded from version 0.06 to 0.08.
2001
2002=item *
2003
ed68b07e
FR
2004C<Tie::RefHash> has been upgraded from version 1.38 to 1.39.
2005
2006=item *
2007
bb3c221a
FR
2008C<Time::HiRes> has been upgraded from version 1.9719 to 1.9721_01.
2009
2010=item *
2011
97fa568b
FR
2012C<Time::Local> has been upgraded from version 1.1901_01 to 1.2000.
2013
2014=item *
2015
a83cb732
FR
2016C<Time::Piece> has been upgraded from version 1.15_01 to 1.20_01.
2017
2018=item *
2019
5076a392
FC
2020C<Unicode::Collate> has been upgraded from version 0.52_01 to 0.73.
2021
1984204c 2022Unicode::Collate has been updated to use Unicode 6.0.0.
5076a392 2023
1984204c
FC
2024Unicode::Collate::Locale now supports a plethora of new locales: ar, be,
2025bg, de__phonebook, hu, hy, kk, mk, nso, om, tn, vi, hr, ig, ja, ko, ru, sq,
2026se, sr, to, uk, zh, zh__big5han, zh__gb2312han, zh__pinyin and zh__stroke.
5076a392
FC
2027
2028The following modules have been added:
2029
2030C<Unicode::Collate::CJK::Big5> for C<zh__big5han> which makes
2031tailoring of CJK Unified Ideographs in the order of CLDR's big5han ordering.
2032
2033C<Unicode::Collate::CJK::GB2312> for C<zh__gb2312han> which makes
2034tailoring of CJK Unified Ideographs in the order of CLDR's gb2312han ordering.
2035
2036C<Unicode::Collate::CJK::JISX0208> which makes tailoring of 6355 kanji
2037(CJK Unified Ideographs) in the JIS X 0208 order.
2038
2039C<Unicode::Collate::CJK::Korean> which makes tailoring of CJK Unified Ideographs
2040in the order of CLDR's Korean ordering.
2041
2042C<Unicode::Collate::CJK::Pinyin> for C<zh__pinyin> which makes
2043tailoring of CJK Unified Ideographs in the order of CLDR's pinyin ordering.
2044
2045C<Unicode::Collate::CJK::Stroke> for C<zh__stroke> which makes
2046tailoring of CJK Unified Ideographs in the order of CLDR's stroke ordering.
2047
5076a392
FC
2048This also sees the switch from using the pure-perl version of this
2049module to the XS version.
2050
2051=item *
2052
ec52b54b
FR
2053C<Unicode::Normalize> has been upgraded from version 1.03 to 1.10.
2054
2055=item *
2056
5076a392
FC
2057C<Unicode::UCD> has been upgraded from version 0.27 to 0.32.
2058
1984204c
FC
2059A new function, C<Unicode::UCD::num()>, has been added. This function
2060returns the numeric value of the string passed it or C<undef> if the string
2061in its entirety has no "safe" numeric value. (For more detail, and for the
2062definition of "safe", see L<Unicode::UCD/num>.)
5076a392 2063
1984204c 2064This upgrade also includes a number of bug fixes:
5076a392
FC
2065
2066=over 4
2067
2068=item charinfo()
2069
2070=over 4
2071
2072=item *
2073
2074It is now updated to Unicode Version 6 with Corrigendum #8, except,
2075as with Perl 5.14, the code point at U+1F514 has no name.
2076
2077=item *
2078
2079The Hangul syllable code points have the correct names, and their
2080decompositions are always output without requiring L<Lingua::KO::Hangul::Util>
2081to be installed.
2082
2083=item *
2084
54c7bb16
FC
2085The CJK (Chinese-Japanese-Korean) code points U+2A700 to U+2B734
2086and U+2B740 to U+2B81D are now properly handled.
5076a392
FC
2087
2088=item *
2089
2090The numeric values are now output for those CJK code points that have them.
2091
2092=item *
2093
2094The names that are output for code points with multiple aliases are now the
2095corrected ones.
2096
2097=back
2098
2099=item charscript()
2100
2101This now correctly returns "Unknown" instead of C<undef> for the script
2102of a code point that hasn't been assigned another one.
2103
2104=item charblock()
2105
2106This now correctly returns "No_Block" instead of C<undef> for the block
2107of a code point that hasn't been assigned to another one.
2108
2109=back
2110
5076a392
FC
2111=item *
2112
2113C<version> has been upgraded from 0.82 to 0.88.
2114
1984204c 2115Due to a bug, now fixed, the C<is_strict> and C<is_lax> functions did not
cdc10f43 2116work when exported (5.12.1).
5076a392
FC
2117
2118=item *
2119
3e625598 2120C<warnings> has been upgraded from version 1.09 to 1.12.
5076a392
FC
2121
2122Calling C<use warnings> without arguments is now significantly more efficient.
2123
4f978a3b
FR
2124=item *
2125
2126C<warnings::register> have been upgraded from version 1.01 to 1.02.
2127
5076a392
FC
2128It is now possible to register warning categories other than the names of
2129packages using C<warnings::register>. See L<perllexwarn> for more information.
2130
2131=item *
2132
62e270c2
FR
2133C<XSLoader> has been upgraded from version 0.10 to 0.13.
2134
2135=item *
2136
5076a392
FC
2137C<VMS::DCLsym> has been upgraded from version 1.03 to 1.05.
2138
2139Two bugs have been fixed [perl #84086]:
2140
2141The symbol table name was lost when tying a hash, due to a thinko in
2142C<TIEHASH>. The result was that all tied hashes interacted with the
2143local symbol table.
2144
2145Unless a symbol table name had been explicitly specified in the call
2146to the constructor, querying the special key ':LOCAL' failed to
2147identify objects connected to the local symbol table.
2148
2149=item *
2150
2151C<Win32> has been upgraded from version 0.39 to 0.44.
2152
1984204c
FC
2153This release has several new functions: C<Win32::GetSystemMetrics>,
2154C<Win32::GetProductInfo>, C<Win32::GetOSDisplayName>.
5076a392 2155
1984204c
FC
2156The names returned by C<Win32::GetOSName> and C<Win32::GetOSDisplayName>
2157have been corrected.
5076a392 2158
3bbe5383
FR
2159=item *
2160
2161C<XS::Typemap> has been upgraded from version 0.03 to 0.05.
2162
5076a392
FC
2163=back
2164
5076a392
FC
2165=head2 Removed Modules and Pragmata
2166
2167The following modules have been removed from the core distribution, and if
2168needed should be installed from CPAN instead.
2169
2170=over
2171
4f978a3b
FR
2172=item *
2173
2174C<Class::ISA> has been removed from the Perl core. Prior version was 0.36.
5076a392 2175
4f978a3b
FR
2176=item *
2177
2178C<Pod::Plainer> has been removed from the Perl core. Prior version was 1.02.
2179
2180=item *
5076a392 2181
4f978a3b 2182C<Switch> has been removed from the Perl core. Prior version was 2.16.
5076a392
FC
2183
2184=back
2185
2186The removal of C<Shell> has been deferred until after 5.14, as the
2187implementation of C<Shell> shipped with 5.12.0 did not correctly issue the
2188warning that it was to be removed from core.
2189
2190=head1 Documentation
2191
5076a392
FC
2192=head2 New Documentation
2193
41e29def 2194=head3 L<perlgpl>
5076a392
FC
2195
2196L<perlgpl> has been updated to contain GPL version 1, as is included in the
cdc10f43 2197F<README> distributed with perl (5.12.1).
5076a392 2198
41e29def 2199=head3 Perl 5.12.x delta files
5076a392 2200
41e29def
FC
2201The perldelta files for Perl 5.12.1 to 5.12.3 have been added from the
2202maintenance branch: L<perl5121delta>, L<perl5122delta>, L<perl5123delta>.
5076a392
FC
2203
2204=head3 L<perlpodstyle>
2205
2206New style guide for POD documentation,
2207split mostly from the NOTES section of the pod2man man page.
2208
41e29def
FC
2209=head3 L<perlsource>, L<perlinterp>, L<perlhacktut>, and L<perlhacktips>
2210
cc13eef1 2211See L</perlhack and perlrepository revamp>, below.
5076a392
FC
2212
2213=head2 Changes to Existing Documentation
2214
41e29def 2215=head3 L<perlmodlib> is now complete
4ed2cea4
FC
2216
2217The perlmodlib page that came with Perl 5.12.0 was missing a lot of
a60ea503 2218modules, due to a bug in the script that generates the list. This has been
cdc10f43 2219fixed [perl #74332] (5.12.1).
4ed2cea4 2220
41e29def 2221=head3 Replace wrong tr/// table in L<perlebcdic>
5076a392 2222
41e29def 2223L<perlebcdic> contains a helpful table to use in tr/// to convert
5076a392
FC
2224between EBCDIC and Latin1/ASCII. Unfortunately, the table was the
2225inverse of the one it describes, though the code that used the table
2226worked correctly for the specific example given.
2227
2228The table has been changed to its inverse, and the sample code changed
2229to correspond, as this is easier for the person trying to follow the
2230instructions since deriving the old table is somewhat more complicated.
2231
2232The table has also been changed to hex from octal, as that is more the norm
2233these days, and the recipes in the pod altered to print out leading
41e29def 2234zeros to make all the values the same length.
5076a392 2235
41e29def 2236=head3 Tricks for user-defined casing
5076a392 2237
41e29def
FC
2238L<perlunicode> now contains an explanation of how to override, mangle
2239and otherwise tweak the way perl handles upper-, lower- and other-case
2240conversions on Unicode data, and how to provide scoped changes to alter
2241one's own code's behaviour without stomping on anybody else.
5076a392
FC
2242
2243=head3 INSTALL explicitly states the requirement for C89
2244
d430b8e7
FC
2245This was already true but it's now Officially Stated For The Record
2246(5.12.2).
5076a392 2247
41e29def 2248=head3 Explanation of C<\xI<HH>> and C<\oI<OOO>> escapes
5076a392 2249
41e29def
FC
2250L<perlop> has been updated with more detailed explanation of these two
2251character escapes.
5076a392 2252
41e29def 2253=head3 C<-0I<NNN>> switch
5076a392 2254
41e29def 2255In L<perlrun>, the behavior of the C<-0NNN> switch for C<-0400> or higher
d430b8e7 2256has been clarified (5.12.2).
5076a392 2257
cdc10f43
FC
2258=head3 Maintenance policy
2259
2260L<perlpolicy> now contains the policy on what patches are acceptable for
2261maintenance branches (5.12.1).
2262
41e29def 2263=head3 Deprecation policy
5076a392 2264
41e29def 2265L<perlpolicy> now contains the policy on compatibility and deprecation
d430b8e7 2266along with definitions of terms like "deprecation" (5.12.2).
5076a392 2267
41e29def 2268=head3 New descriptions in L<perldiag>
5076a392
FC
2269
2270The following existing diagnostics are now documented:
2271
2272=over 4
2273
2274=item *
2275
2276L<Ambiguous use of %c resolved as operator %c|perldiag/"Ambiguous use of %c resolved as operator %c">
2277
2278=item *
2279
2280L<Ambiguous use of %c{%s} resolved to %c%s|perldiag/"Ambiguous use of %c{%s} resolved to %c%s">
2281
2282=item *
2283
2284L<Ambiguous use of %c{%s%s} resolved to %c%s%s|perldiag/"Ambiguous use of %c{%s%s} resolved to %c%s%s">
2285
2286=item *
2287
2288L<Ambiguous use of -%s resolved as -&%s()|perldiag/"Ambiguous use of -%s resolved as -&%s()">
2289
2290=item *
2291
2292L<Invalid strict version format (%s)|perldiag/"Invalid strict version format (%s)">
2293
2294=item *
2295
2296L<Invalid version format (%s)|perldiag/"Invalid version format (%s)">
2297
2298=item *
2299
2300L<Invalid version object|perldiag/"Invalid version object">
2301
2302=back
2303
5076a392
FC
2304=head3 L<perlbook>
2305
41e29def 2306L<perlbook> has been expanded to cover many more popular books.
5076a392 2307
41e29def 2308=head3 C<SvTRUE> macro
5076a392 2309
41e29def
FC
2310The documentation for the C<SvTRUE> macro in
2311L<perlapi> was simply wrong in stating that
a60ea503 2312get-magic is not processed. It has been corrected.
5076a392 2313
41e29def 2314=head3 L<perlvar> revamp
5076a392 2315
41e29def 2316L<perlvar> reorders the variables and groups them by topic. Each variable
5076a392 2317introduced after Perl 5.000 notes the first version in which it is
41e29def 2318available. L<perlvar> also has a new section for deprecated variables to
5076a392
FC
2319note when they were removed.
2320
41e29def 2321=head3 Array and hash slices in scalar context
5076a392 2322
41e29def 2323These are now documented in L<perldata>.
5076a392 2324
41e29def 2325=head3 C<use locale> and formats
5076a392
FC
2326
2327L<perlform> and L<perllocale> have been corrected to state that
2328C<use locale> affects formats.
2329
5076a392
FC
2330=head3 L<overload>
2331
a60ea503 2332L<overload>'s documentation has practically undergone a rewrite. It
5076a392
FC
2333is now much more straightforward and clear.
2334
cc13eef1 2335=head3 perlhack and perlrepository revamp
5076a392
FC
2336
2337The L<perlhack> and perlrepository documents have been heavily edited and
2338split up into several new documents.
2339
2340The L<perlhack> document is now much shorter, and focuses on the Perl 5
a60ea503
FC
2341development process and submitting patches
2342to Perl. The technical content has
5076a392 2343been moved to several new documents, L<perlsource>, L<perlinterp>,
a60ea503 2344L<perlhacktut>, and L<perlhacktips>. This technical content has only been
5076a392
FC
2345lightly edited.
2346
a60ea503
FC
2347The perlrepository document has been renamed to
2348L<perlgit>. This new document is just a how-to
2349on using git with the Perl source code. Any other content
5076a392
FC
2350that used to be in perlrepository has been moved to perlhack.
2351
41e29def 2352=head3 Time::Piece examples
5076a392
FC
2353
2354Examples in L<perlfaq4> have been updated to show the use of
41e29def 2355L<Time::Piece>.
5076a392
FC
2356
2357=head1 Diagnostics
2358
2359The following additions or changes have been made to diagnostic output,
2360including warnings and fatal error messages. For the complete list of
2361diagnostic messages, see L<perldiag>.
2362
2363=head2 New Diagnostics
2364
a593b319
FC
2365=head3 New Errors
2366
5076a392
FC
2367=over
2368
a593b319 2369=item Closure prototype called
5076a392 2370
a593b319
FC
2371This error occurs when a subroutine reference passed to an attribute
2372handler is called, if the subroutine is a closure [perl #68560].
5076a392 2373
a593b319 2374=item Insecure user-defined property %s
5076a392 2375
a593b319
FC
2376Perl detected tainted data when trying to compile a regular
2377expression that contains a call to a user-defined character property
2378function, i.e. C<\p{IsFoo}> or C<\p{InFoo}>.
2379See L<perlunicode/User-Defined Character Properties> and L<perlsec>.
5076a392 2380
a593b319 2381=item panic: gp_free failed to free glob pointer - something is repeatedly re-creating entries
5076a392 2382
a593b319
FC
2383This new error is triggered if a destructor called on an object in a
2384typeglob that is being freed creates a new typeglob entry containing an
2385object with a destructor that creates a new entry containing an object....
5076a392 2386
a593b319 2387=item Parsing code internal error (%s)
5076a392 2388
a593b319
FC
2389This new fatal error is produced when parsing
2390code supplied by an extension violates the
2391parser's API in a detectable way.
5076a392 2392
a593b319 2393=item refcnt: fd %d%s
5076a392 2394
a593b319
FC
2395This new error only occurs if a internal consistency check fails when a
2396pipe is about to be closed.
5076a392 2397
a593b319 2398=item Regexp modifier "/%c" may not appear twice
5076a392 2399
a593b319
FC
2400The regular expression pattern has one of the
2401mutually exclusive modifiers repeated.
5076a392 2402
a593b319 2403=item Regexp modifiers "/%c" and "/%c" are mutually exclusive
5076a392 2404
a593b319
FC
2405The regular expression pattern has more than one of the mutually
2406exclusive modifiers.
5076a392 2407
a593b319 2408=item Using !~ with %s doesn't make sense
5076a392 2409
a593b319 2410This error occurs when C<!~> is used with C<s///r> or C<y///r>.
5076a392 2411
a593b319 2412=back
5076a392 2413
a593b319 2414=head3 New Warnings
5076a392 2415
a593b319 2416=over
5076a392 2417
a593b319 2418=item "\b{" is deprecated; use "\b\{" instead
5076a392 2419
a593b319 2420=item "\B{" is deprecated; use "\B\{" instead
5076a392 2421
a593b319
FC
2422Use of an unescaped "{" immediately following a C<\b> or C<\B> is now
2423deprecated so as to reserve its use for Perl itself in a future release.
5076a392 2424
a593b319 2425=item Operation "%s" returns its argument for ...
5076a392 2426
a593b319 2427Performing an operation requiring Unicode semantics (such as case-folding)
a60ea503
FC
2428on a Unicode surrogate or a non-Unicode character now triggers this
2429warning.
5076a392 2430
a593b319
FC
2431=item Use of qw(...) as parentheses is deprecated
2432
2433See L</"Use of qw(...) as parentheses">, above, for details.
5076a392
FC
2434
2435=back
2436
2437=head2 Changes to Existing Diagnostics
2438
2439=over 4
2440
2441=item *
2442
4ed2cea4
FC
2443The "Variable $foo is not imported" warning that precedes a
2444C<strict 'vars'> error has now been assigned the "misc" category, so that
2445C<no warnings> will suppress it [perl #73712].
2446
2447=item *
2448
5076a392
FC
2449C<warn> and C<die> now produce 'Wide character' warnings when fed a
2450character outside the byte range if STDERR is a byte-sized handle.
2451
2452=item *
2453
2454The 'Layer does not match this perl' error message has been replaced with
a593b319 2455these more helpful messages [perl #73754]:
5076a392
FC
2456
2457=over 4
2458
2459=item *
2460
2461PerlIO layer function table size (%d) does not match size expected by this
2462perl (%d)
2463
2464=item *
2465
2466PerlIO layer instance size (%d) does not match size expected by this perl
2467(%d)
2468
2469=back
2470
5076a392
FC
2471=item *
2472
2473The "Found = in conditional" warning that is emitted when a constant is
2474assigned to a variable in a condition is now withheld if the constant is
2475actually a subroutine or one generated by C<use constant>, since the value
2476of the constant may not be known at the time the program is written
2477[perl #77762].
2478
2479=item *
2480
2481Previously, if none of the C<gethostbyaddr>, C<gethostbyname> and
2482C<gethostent> functions were implemented on a given platform, they would
2483all die with the message 'Unsupported socket function "gethostent" called',
2484with analogous messages for C<getnet*> and C<getserv*>. This has been
2485corrected.
2486
2487=item *
2488
a593b319
FC
2489The warning message about unrecognized regular expression escapes passed
2490through has been changed to include any literal '{' following the
2491two-character escape. E.g., "\q{" is now emitted instead of "\q".
5076a392
FC
2492
2493=back
2494
2495=head1 Utility Changes
2496
0b88cc74 2497=head3 L<perlbug>
5076a392
FC
2498
2499=over 4
2500
2501=item *
2502
0b88cc74
FC
2503L<perlbug> now looks in the EMAIL environment variable for a return address
2504if the REPLY-TO and REPLYTO variables are empty.
5076a392
FC
2505
2506=item *
2507
0b88cc74
FC
2508L<perlbug> did not previously generate a From: header, potentially
2509resulting in dropped mail. Now it does include that header.
5076a392
FC
2510
2511=item *
2512
0b88cc74 2513The user's address is now used as the return-path.
4ed2cea4 2514
0b88cc74
FC
2515Many systems these days don't have a valid Internet domain name and
2516perlbug@perl.org does not accept email with a return-path that does
2517not resolve. So the user's address is now passed to sendmail so it's
2518less likely to get stuck in a mail queue somewhere [perl #82996].
5076a392 2519
2c389f6c
FC
2520=item *
2521
d430b8e7
FC
2522L<perlbug> now always gives the reporter a chance to change the email
2523address it guesses for them (5.12.2).
2524
2525=item *
2526
2527L<perlbug> should no longer warn about uninitialized values when using the C<-d>
2528and C<-v> options (5.12.2).
2c389f6c 2529
5076a392
FC
2530=back
2531
0b88cc74 2532=head3 L<perl5db.pl>
5076a392 2533
0b88cc74 2534=over
5076a392
FC
2535
2536=item *
2537
0b88cc74
FC
2538The remote terminal works after forking and spawns new sessions - one
2539for each forked process.
5076a392
FC
2540
2541=back
2542
0b88cc74 2543=head3 L<ptargrep>
5076a392
FC
2544
2545=over 4
2546
2547=item *
2548
0b88cc74
FC
2549L<ptargrep> is a new utility to apply pattern matching to the contents of
2550files in a tar archive. It comes with C<Archive::Tar>.
5076a392
FC
2551
2552=back
2553
2554=head1 Configuration and Compilation
2555
61752d82
FC
2556See also L</"Naming fixes in Policy_sh.SH may invalidate Policy.sh">,
2557above.
2558
5076a392
FC
2559=over 4
2560
2561=item *
2562
87595b22
FC
2563CCINCDIR and CCLIBDIR for the mingw64
2564cross-compiler are now correctly under
5076a392
FC
2565$(CCHOME)\mingw\include and \lib rather than immediately below $(CCHOME).
2566
5076a392
FC
2567This means the 'incpath', 'libpth', 'ldflags', 'lddlflags' and
2568'ldflags_nolargefiles' values in Config.pm and Config_heavy.pl are now
87595b22 2569set correctly.
5076a392
FC
2570
2571=item *
2572
87595b22
FC
2573'make test.valgrind' has been adjusted to account for cpan/dist/ext
2574separation.
5076a392
FC
2575
2576=item *
2577
2578On compilers that support it, C<-Wwrite-strings> is now added to cflags by
2579default.
2580
2581=item *
2582
2583The C<Encode> module can now (once again) be included in a static Perl
2584build. The special-case handling for this situation got broken in Perl
25855.11.0, and has now been repaired.
2586
1e463951
FC
2587=item *
2588
2589The previous default size of a PerlIO buffer (4096 bytes) has been increased
2590to the larger of 8192 bytes and your local BUFSIZ. Benchmarks show that doubling
2591this decade-old default increases read and write performance in the neighborhood
2592of 25% to 50% when using the default layers of perlio on top of unix. To choose
2593a non-default size, such as to get back the old value or to obtain an even
2594larger value, configure with:
2595
2596 ./Configure -Accflags=-DPERLIOBUF_DEFAULT_BUFSIZ=N
2597
2598where N is the desired size in bytes; it should probably be a multiple of
2599your page size.
2600
d430b8e7
FC
2601=item *
2602
2603An "incompatible operand types" error in ternary expressions when building
2604with C<clang> has been fixed (5.12.2).
2605
2606=item *
2607
2608Perl now skips setuid C<File::Copy> tests on partitions it detects to be mounted
2609as C<nosuid> (5.12.2).
2610
5076a392
FC
2611=back
2612
5076a392
FC
2613=head1 Platform Support
2614
5076a392
FC
2615=head2 New Platforms
2616
5076a392
FC
2617=over 4
2618
2619=item AIX
2620
cdc10f43 2621Perl now builds on AIX 4.2 (5.12.1).
5076a392
FC
2622
2623=back
2624
2625=head2 Discontinued Platforms
2626
2627=over 4
2628
5076a392
FC
2629=item Apollo DomainOS
2630
2631The last vestiges of support for this platform have been excised from the
a60ea503
FC
2632Perl distribution. It was officially discontinued
2633in version 5.12.0. It had
5076a392
FC
2634not worked for years before that.
2635
2636=item MacOS Classic
2637
2638The last vestiges of support for this platform have been excised from the
a60ea503 2639Perl distribution. It was officially discontinued in an earlier version.
5076a392
FC
2640
2641=back
2642
2643=head2 Platform-Specific Notes
2644
d430b8e7
FC
2645=head3 AIX
2646
2647=over
2648
2649=item *
2650
2651F<README.aix> has been updated with information about the XL C/C++ V11 compiler
2652suite (5.12.2).
2653
2654=back
2655
2656=head3 ARM
2657
2658=over
2659
2660=item *
2661
2662The C<d_u32align> configuration probe on ARM has been fixed (5.12.2).
2663
2664=back
2665
554003a2 2666=head3 Cygwin
5076a392
FC
2667
2668=over 4
2669
2670=item *
2671
554003a2 2672MakeMaker has been updated to build man pages on cygwin.
5076a392
FC
2673
2674=item *
2675
554003a2
FC
2676Improved rebase behaviour
2677
2678If a dll is updated on cygwin the old imagebase address is reused.
2679This solves most rebase errors, especially when updating on core dll's.
2680See L<http://www.tishler.net/jason/software/rebase/rebase-2.4.2.README> for more information.
5076a392
FC
2681
2682=item *
2683
554003a2 2684Support for the standard cygwin dll prefix, which is e.g. needed for FFI's
5076a392
FC
2685
2686=item *
2687
554003a2 2688Updated build hints file
5076a392
FC
2689
2690=back
2691
cdc10f43
FC
2692=head3 FreeBSD 7
2693
2694=over
2695
2696=item *
2697
2698FreeBSD 7 no longer contains F</usr/bin/objformat>. At build time,
2699Perl now skips the F<objformat> check for versions 7 and higher and
2700assumes ELF (5.12.1).
2701
2702=back
2703
2704=head3 HP-UX
2705
2706=over
2707
2708=item *
2709
2710Perl now allows -Duse64bitint without promoting to use64bitall on HP-UX
2711(5.12.1).
2712
2713=back
2714
554003a2 2715=head3 IRIX
5076a392 2716
a60ea503
FC
2717=over
2718
2719=item *
2720
5076a392
FC
2721Conversion of strings to floating-point numbers is now more accurate on
2722IRIX systems [perl #32380].
2723
a60ea503
FC
2724=back
2725
554003a2 2726=head3 Mac OS X
5076a392 2727
a60ea503
FC
2728=over
2729
2730=item *
2731
5076a392
FC
2732Early versions of Mac OS X (Darwin) had buggy implementations of the
2733C<setregid>, C<setreuid>, C<setrgid> and C<setruid> functions, so perl
2734would pretend they did not exist.
2735
2736These functions are now recognised on Mac OS 10.5 (Leopard; Darwin 9) and
2737higher, as they have been fixed [perl #72990].
2738
a60ea503
FC
2739=back
2740
554003a2 2741=head3 MirBSD
5076a392 2742
a60ea503
FC
2743=over
2744
2745=item *
2746
554003a2
FC
2747Previously if you built perl with a shared libperl.so on MirBSD (the
2748default config), it would work up to the installation; however, once
2749installed, it would be unable to find libperl. So path handling is now
2750treated as in the other BSD dialects.
5076a392 2751
a60ea503
FC
2752=back
2753
554003a2 2754=head3 NetBSD
5076a392 2755
a60ea503
FC
2756=over
2757
2758=item *
2759
554003a2
FC
2760The NetBSD hints file has been changed to make the system's malloc the
2761default.
5076a392 2762
a60ea503
FC
2763=back
2764
554003a2 2765=head3 Recent OpenBSDs now use perl's malloc
5076a392 2766
a60ea503
FC
2767=over
2768
2769=item *
2770
554003a2
FC
2771OpenBSD E<gt> 3.7 has a new malloc implementation which is mmap-based
2772and as such can release memory back to the OS; however, perl's use of
2773this malloc causes a substantial slowdown so we now default to using
2774perl's malloc instead [perl #75742].
5076a392 2775
a60ea503
FC
2776=back
2777
554003a2 2778=head3 OpenVOS
5076a392 2779
a60ea503
FC
2780=over
2781
2782=item *
2783
554003a2 2784perl now builds again with OpenVOS (formerly known as Stratus VOS)
5a553547 2785[perl #78132] (5.12.3).
5076a392 2786
a60ea503
FC
2787=back
2788
554003a2 2789=head3 Solaris
5076a392 2790
a60ea503
FC
2791=over
2792
2793=item *
2794
2795DTrace is now supported on Solaris. There used to be build failures, but
5a553547 2796these have been fixed [perl #73630] (5.12.3).
5076a392 2797
a60ea503
FC
2798=back
2799
554003a2 2800=head3 VMS
5076a392
FC
2801
2802=over
2803
2804=item *
2805
cdc10f43
FC
2806It's now possible to build extensions on older (pre 7.3-2) VMS systems.
2807
2808DCL symbol length was limited to 1K up until about seven years or
2809so ago, but there was no particularly deep reason to prevent those
2810older systems from configuring and building Perl (5.12.1).
2811
2812=item *
2813
2814We fixed the previously-broken C<-Uuseperlio> build on VMS.
2815
2816We were checking a variable that doesn't exist in the non-default
2817case of disabling perlio. Now we only look at it when it exists (5.12.1).
2818
2819=item *
2820
2821We fixed the -Uuseperlio command-line option in configure.com.
2822
2823Formerly it only worked if you went through all the questions
2824interactively and explicitly answered no (5.12.1).
2825
2826=item *
2827
554003a2 2828C<PerlIOUnix_open> now honours the default permissions on VMS.
5076a392 2829
554003a2
FC
2830When C<perlio> became the default and C<unixio> became the default bottom layer,
2831the most common path for creating files from Perl became C<PerlIOUnix_open>,
2832which has always explicitly used C<0666> as the permission mask.
5076a392 2833
554003a2
FC
2834To avoid this, C<0777> is now passed as the permissions to C<open()>. In the
2835VMS CRTL, C<0777> has a special meaning over and above intersecting with the
2836current umask; specifically, it allows Unix syscalls to preserve native default
5a553547
FC
2837permissions (5.12.3).
2838
2839=item *
2840
2841Spurious record boundaries are no longer
2842introduced by the PerlIO layer during output (5.12.3).
5076a392
FC
2843
2844=item *
2845
554003a2
FC
2846The shortening of symbols longer than 31 characters in the C sources is
2847now done by the compiler rather than by xsubpp (which could only do so
2848for generated symbols in XS code).
5076a392
FC
2849
2850=item *
2851
554003a2
FC
2852Record-oriented files (record format variable or variable with fixed control)
2853opened for write by the perlio layer will now be line-buffered to prevent the
2854introduction of spurious line breaks whenever the perlio buffer fills up.
5076a392 2855
d430b8e7
FC
2856=item *
2857
a60ea503
FC
2858F<git_version.h> is now installed on VMS. This
2859was an oversight in v5.12.0 which
d430b8e7
FC
2860caused some extensions to fail to build (5.12.2).
2861
2862=item *
2863
2864Several memory leaks in L<stat()|perlfunc/"stat FILEHANDLE"> have been fixed (5.12.2).
2865
2866=item *
2867
2868A memory leak in C<Perl_rename()> due to a double allocation has been
2869fixed (5.12.2).
2870
2871=item *
2872
2873A memory leak in C<vms_fid_to_name()> (used by C<realpath()> and
2874C<realname()>) has been fixed (5.12.2).
2875
5076a392
FC
2876=back
2877
554003a2 2878=head3 Windows
5076a392 2879
5a1f7719
FC
2880See also L</"fork() emulation will not wait for signalled children"> and
2881L</"Perl source code is read in text mode on Windows">, above.
2882
5076a392
FC
2883=over 4
2884
2885=item *
2886
554003a2 2887Fixed build process for SDK2003SP1 compilers.
5076a392 2888
554003a2 2889=item *
5076a392 2890
01b1a9e4
FC
2891Compilation with Visual Studio 2010 is now supported.
2892
2893=item *
2894
554003a2
FC
2895When using old 32-bit compilers, the define C<_USE_32BIT_TIME_T> will now
2896be set in C<$Config{ccflags}>. This improves portability when compiling
2897XS extensions using new compilers, but for a perl compiled with old 32-bit
2898compilers.
5076a392
FC
2899
2900=item *
2901
554003a2
FC
2902C<$Config{gccversion}> is now set correctly when perl is built using the
2903mingw64 compiler from L<http://mingw64.org> [perl #73754].
5076a392 2904
554003a2
FC
2905=item *
2906
d430b8e7
FC
2907When building Perl with the mingw64 x64 cross-compiler C<incpath>,
2908C<libpth>, C<ldflags>, C<lddlflags> and C<ldflags_nolargefiles> values
2909in F<Config.pm> and F<Config_heavy.pl> were not previously being set
2910correctly because, with that compiler, the include and lib directories
2911are not immediately below C<$(CCHOME)> (5.12.2).
2912
2913=item *
2914
554003a2
FC
2915The build process proceeds more smoothly with mingw and dmake when
2916F<C:\MSYS\bin> is in the PATH, due to a C<Cwd> fix.
5076a392
FC
2917
2918=item *
2919
554003a2
FC
2920Support for building with Visual C++ 2010 is now underway, but is not yet
2921complete. See F<README.win32> or L<perlwin32> for more details.
5076a392 2922
554003a2
FC
2923=item *
2924
2925The option to use an externally-supplied C<crypt()>, or to build with no
2926C<crypt()> at all, has been removed. Perl supplies its own C<crypt()>
2927implementation for Windows, and the political situation that required
2928this part of the distribution to sometimes be omitted is long gone.
5076a392
FC
2929
2930=back
2931
2932=head1 Internal Changes
2933
1e463951 2934=head2 New APIs
5076a392 2935
1e463951 2936=head3 CLONE_PARAMS structure added to ease correct thread creation
5076a392 2937
1e463951
FC
2938Modules that create threads should now create C<CLONE_PARAMS> structures
2939by calling the new function C<Perl_clone_params_new()>, and free them with
2940C<Perl_clone_params_del()>. This will ensure compatibility with any future
2941changes to the internals of the C<CLONE_PARAMS> structure layout, and that
2942it is correctly allocated and initialised.
5076a392 2943
1e463951 2944=head3 New parsing functions
5076a392 2945
1e463951
FC
2946Several functions have been added for parsing statements or multiple
2947statements:
5076a392 2948
1e463951 2949=over
5076a392
FC
2950
2951=item *
2952
1e463951 2953C<parse_fullstmt> parses a complete Perl statement.
5076a392
FC
2954
2955=item *
2956
1e463951
FC
2957C<parse_stmtseq> parses a sequence of statements, up
2958to closing brace or EOF.
5076a392
FC
2959
2960=item *
2961
1e463951 2962C<parse_block> parses a block [perl #78222].
5076a392
FC
2963
2964=item *
2965
1e463951
FC
2966C<parse_barestmt> parses a statement
2967without a label.
5076a392
FC
2968
2969=item *
2970
1e463951 2971C<parse_label> parses a statement label, separate from statements.
5076a392 2972
1e463951 2973=back
5076a392 2974
1e463951
FC
2975The
2976L<C<parse_fullexpr()>|perlapi/parse_fullexpr>,
2977L<C<parse_listexpr()>|perlapi/parse_listexpr>,
2978L<C<parse_termexpr()>|perlapi/parse_termexpr>, and
2979L<C<parse_arithexpr()>|perlapi/parse_arithexpr>
2980functions have been added to the API. They perform
2981recursive-descent parsing of expressions at various precedence levels.
2982They are expected to be used by syntax plugins.
5076a392 2983
1e463951 2984See L<perlapi> for details.
5076a392 2985
1e463951 2986=head3 Hints hash API
5076a392 2987
1e463951
FC
2988A new C API for introspecting the hinthash C<%^H> at runtime has been
2989added. See C<cop_hints_2hv>, C<cop_hints_fetchpvn>, C<cop_hints_fetchpvs>,
2990C<cop_hints_fetchsv>, and C<hv_copy_hints_hv> in L<perlapi> for details.
5076a392 2991
1e463951
FC
2992A new, experimental API has been added for accessing the internal
2993structure that Perl uses for C<%^H>. See the functions beginning with
2994C<cophh_> in L<perlapi>.
5076a392 2995
1e463951 2996=head3 C interface to C<caller()>
5076a392 2997
1e463951
FC
2998The C<caller_cx> function has been added as an XSUB-writer's equivalent of
2999C<caller()>. See L<perlapi> for details.
5076a392 3000
1e463951 3001=head3 Custom per-subroutine check hooks
5076a392 3002
1e463951
FC
3003XS code in an extension module can now annotate a subroutine (whether
3004implemented in XS or in Perl) so that nominated XS code will be called
3005at compile time (specifically as part of op checking) to change the op
3006tree of that subroutine. The compile-time check function (supplied by
3007the extension module) can implement argument processing that can't be
3008expressed as a prototype, generate customised compile-time warnings,
3009perform constant folding for a pure function, inline a subroutine
3010consisting of sufficiently simple ops, replace the whole call with a
3011custom op, and so on. This was previously all possible by hooking the
3012C<entersub> op checker, but the new mechanism makes it easy to tie the
3013hook to a specific subroutine. See L<perlapi/cv_set_call_checker>.
5076a392 3014
1e463951
FC
3015To help in writing custom check hooks, several subtasks within standard
3016C<entersub> op checking have been separated out and exposed in the API.
5076a392 3017
1e463951 3018=head3 Improved support for custom OPs
5076a392 3019
1e463951
FC
3020Custom ops can now be registered with the new C<custom_op_register> C
3021function and the C<XOP> structure. This will make it easier to add new
3022properties of custom ops in the future. Two new properties have been added
3023already, C<xop_class> and C<xop_peep>.
5076a392 3024
1e463951
FC
3025C<xop_class> is one of the OA_*OP constants, and allows L<B> and other
3026introspection mechanisms to work with custom ops
3027that aren't BASEOPs. C<xop_peep> is a pointer to
3028a function that will be called for ops of this
3029type from C<Perl_rpeep>.
5076a392 3030
1e463951
FC
3031See L<perlguts/Custom Operators> and L<perlapi/Custom Operators> for more
3032detail.
5076a392 3033
1e463951
FC
3034The old C<PL_custom_op_names>/C<PL_custom_op_descs> interface is still
3035supported but discouraged.
5076a392 3036
1e463951 3037=head3 Scope hooks
5076a392 3038
1e463951
FC
3039It is now possible for XS code to hook into Perl's lexical scope
3040mechanism at compile time, using the new C<Perl_blockhook_register>
a60ea503 3041function. See L<perlguts/"Compile-time scope hooks">.
5076a392 3042
1e463951 3043=head3 The recursive part of the peephole optimizer is now hookable
5076a392
FC
3044
3045In addition to C<PL_peepp>, for hooking into the toplevel peephole optimizer, a
3046C<PL_rpeepp> is now available to hook into the optimizer recursing into
3047side-chains of the optree.
3048
1e463951 3049=head3 New non-magical variants of existing functions
5076a392 3050
1e463951
FC
3051The following functions/macros have been added to the API. The C<*_nomg>
3052macros are equivalent to their non-_nomg variants, except that they ignore
3053get-magic. Those ending in C<_flags> allow one to specify whether
3054get-magic is processed.
5076a392 3055
1e463951
FC
3056 sv_2bool_flags
3057 SvTRUE_nomg
3058 sv_2nv_flags
3059 SvNV_nomg
3060 sv_cmp_flags
3061 sv_cmp_locale_flags
3062 sv_eq_flags
3063 sv_collxfrm_flags
5076a392 3064
1e463951 3065In some of these cases, the non-_flags functions have
5076a392
FC
3066been replaced with wrappers around the new functions.
3067
1e463951 3068=head3 pv/pvs/sv versions of existing functions
5076a392 3069
1e463951 3070Many functions ending with pvn now have equivalent pv/pvs/sv versions.
5076a392 3071
1e463951 3072=head3 List op-building functions
5076a392 3073
1e463951
FC
3074List op-building functions have been added to the
3075API. See L<op_append_elem|perlapi/op_append_elem>,
3076L<op_append_list|perlapi/op_append_list>, and
3077L<op_prepend_elem|perlapi/op_prepend_elem> in L<perlapi>.
5076a392 3078
1e463951 3079=head3 C<LINKLIST>
5076a392 3080
1e463951
FC
3081The L<LINKLIST|perlapi/LINKLIST> macro, part of op building that
3082constructs the execution-order op chain, has been added to the API.
5076a392 3083
1e463951 3084=head3 Localisation functions
5076a392 3085
1e463951
FC
3086The C<save_freeop>, C<save_op>, C<save_pushi32ptr> and C<save_pushptrptr>
3087functions have been added to the API.
5076a392 3088
1e463951 3089=head3 Stash names
5076a392 3090
1e463951
FC
3091A stash can now have a list of effective names in addition to its usual
3092name. The first effective name can be accessed via the C<HvENAME> macro,
3093which is now the recommended name to use in MRO linearisations (C<HvNAME>
3094being a fallback if there is no C<HvENAME>).
5076a392 3095
1e463951
FC
3096These names are added and deleted via C<hv_ename_add> and
3097C<hv_ename_delete>. These two functions are I<not> part of the API.
5076a392 3098
1e463951 3099=head3 New functions for finding and removing magic
5076a392 3100
1e463951
FC
3101The L<C<mg_findext()>|perlapi/mg_findext> and
3102L<C<sv_unmagicext()>|perlapi/sv_unmagicext>
3103functions have been added to the API.
3104They allow extension authors to find and remove magic attached to
3105scalars based on both the magic type and the magic virtual table, similar to how
3106C<sv_magicext()> attaches magic of a certain type and with a given virtual table
3107to a scalar. This eliminates the need for extensions to walk the list of
3108C<MAGIC> pointers of an C<SV> to find the magic that belongs to them.
5076a392 3109
1e463951 3110=head3 C<find_rundefsv>
5076a392 3111
1e463951
FC
3112This function returns the SV representing C<$_>, whether it's lexical
3113or dynamic.
5076a392 3114
1e463951 3115=head3 C<Perl_croak_no_modify>
5076a392 3116
1e463951
FC
3117C<Perl_croak_no_modify()> is short-hand for
3118C<Perl_croak("%s", PL_no_modify)>.
5076a392 3119
1e463951 3120=head3 C<PERL_STATIC_INLINE> define
5076a392 3121
1e463951
FC
3122The C<PERL_STATIC_INLINE> define has been added to provide the best-guess
3123incantation to use for static inline functions, if the C compiler supports
3124C99-style static inline. If it doesn't, it'll give a plain C<static>.
5076a392 3125
1e463951
FC
3126C<HAS_STATIC_INLINE> can be used to check if the compiler actually supports
3127inline functions.
5076a392 3128
1e463951 3129=head3 New C<pv_escape> option for hexadecimal escapes
5076a392 3130
1e463951
FC
3131A new option, C<PERL_PV_ESCAPE_NONASCII>, has been added to C<pv_escape> to
3132dump all characters above ASCII in hexadecimal. Before, one could get all
3133characters as hexadecimal or the Latin1 non-ASCII as octal.
5076a392 3134
1e463951 3135=head3 C<lex_start>
5076a392 3136
1e463951 3137C<lex_start> has been added to the API, but is considered experimental.
5076a392 3138
1e463951 3139=head3 C<op_scope()> and C<op_lvalue()>
5076a392 3140
1e463951
FC
3141The C<op_scope()> and C<op_lvalue()> functions have been added to the API,
3142but are considered experimental.
5076a392 3143
1e463951 3144=head2 C API Changes
5076a392 3145
1e463951 3146=head3 C<PERL_POLLUTE> has been removed
5076a392 3147
1e463951
FC
3148The option to define C<PERL_POLLUTE> to expose older 5.005 symbols for
3149backwards compatibility has been removed. It's use was always discouraged,
3150and MakeMaker contains a more specific escape hatch:
5076a392 3151
1e463951 3152 perl Makefile.PL POLLUTE=1
5076a392 3153
1e463951
FC
3154This can be used for modules that have not been upgraded to 5.6 naming
3155conventions (and really should be completely obsolete by now).
5076a392 3156
1e463951 3157=head3 Check API compatibility when loading XS modules
5076a392 3158
1e463951
FC
3159When perl's API changes in incompatible ways (which usually happens between
3160major releases), XS modules compiled for previous versions of perl will not
3161work anymore. They will need to be recompiled against the new perl.
5076a392 3162
1e463951
FC
3163In order to ensure that modules are recompiled, and to prevent users from
3164accidentally loading modules compiled for old perls into newer ones, the
3165C<XS_APIVERSION_BOOTCHECK> macro has been added. That macro, which is
3166called when loading every newly compiled extension, compares the API
3167version of the running perl with the version a module has been compiled for
3168and raises an exception if they don't match.
5076a392 3169
1e463951 3170=head3 Perl_fetch_cop_label
5076a392 3171
1e463951
FC
3172The first argument of the C API function C<Perl_fetch_cop_label> has changed
3173from C<struct refcounted he *> to C<COP *>, to insulate the user from
3174implementation details.
5076a392 3175
1e463951
FC
3176This API function was marked as "may change", and likely isn't in use outside
3177the core. (Neither an unpacked CPAN, nor Google's codesearch, finds any other
3178references to it.)
5076a392 3179
1e463951 3180=head3 GvCV() and GvGP() are no longer lvalues
5076a392 3181
1e463951
FC
3182The new GvCV_set() and GvGP_set() macros are now provided to replace
3183assignment to those two macros.
5076a392 3184
1e463951
FC
3185This allows a future commit to eliminate some backref magic between GV
3186and CVs, which will require complete control over assignment to the
3187gp_cv slot.
5076a392 3188
1e463951 3189=head3 CvGV() is no longer an lvalue
5076a392 3190
1e463951
FC
3191Under some circumstances, the C<CvGV()> field of a CV is now
3192reference-counted. To ensure consistent behaviour, direct assignment to
3193it, for example C<CvGV(cv) = gv> is now a compile-time error. A new macro,
3194C<CvGV_set(cv,gv)> has been introduced to perform this operation
3195safely. Note that modification of this field is not part of the public
3196API, regardless of this new macro (and despite its being listed in this section).
5076a392 3197
1e463951 3198=head3 CvSTASH() is no longer an lvalue
5076a392 3199
1e463951
FC
3200The C<CvSTASH()> macro can now only be used as an rvalue. C<CvSTASH_set()>
3201has been added to replace assignment to C<CvSTASH()>. This is to ensure
3202that backreferences are handled properly. These macros are not part of the
3203API.
5076a392 3204
1e463951 3205=head3 Calling conventions for C<newFOROP> and C<newWHILEOP>
5076a392 3206
1e463951
FC
3207The way the parser handles labels has been cleaned up and refactored. As a
3208result, the C<newFOROP()> constructor function no longer takes a parameter
3209stating what label is to go in the state op.
5076a392 3210
1e463951
FC
3211The C<newWHILEOP()> and C<newFOROP()> functions no longer accept a line
3212number as a parameter.
5076a392 3213
1e463951 3214=head3 Flags passed to C<uvuni_to_utf8_flags> and C<utf8n_to_uvuni>
5076a392 3215
1e463951
FC
3216Some of the flags parameters to uvuni_to_utf8_flags() and
3217utf8n_to_uvuni() have changed. This is a result of Perl's now allowing
5076a392
FC
3218internal storage and manipulation of code points that are problematic
3219in some situations. Hence, the default actions for these functions has
3220been complemented to allow these code points. The new flags are
3221documented in L<perlapi>. Code that requires the problematic code
483b16f3 3222points to be rejected needs to change to use the new flags. Some flag
5076a392
FC
3223names are retained for backward source compatibility, though they do
3224nothing, as they are now the default. However the flags
3225C<UNICODE_ALLOW_FDD0>, C<UNICODE_ALLOW_FFFF>, C<UNICODE_ILLEGAL>, and
3226C<UNICODE_IS_ILLEGAL> have been removed, as they stem from a
3227fundamentally broken model of how the Unicode non-character code points
3228should be handled, which is now described in
52d6192b
FC
3229L<perlunicode/Non-character code points>. See also the Unicode section
3230under L</Selected Bug Fixes>.
5076a392 3231
1e463951 3232=head2 Deprecated C APIs
5076a392 3233
1e463951 3234=over
5076a392 3235
1e463951 3236=item C<Perl_ptr_table_clear>
5076a392 3237
1e463951
FC
3238C<Perl_ptr_table_clear> is no longer part of Perl's public API. Calling it
3239now generates a deprecation warning, and it will be removed in a future
3240release.
5076a392 3241
1e463951 3242=item C<sv_compile_2op>
5076a392 3243
1e463951
FC
3244The C<sv_compile_2op()> API function is now deprecated. Searches suggest
3245that nothing on CPAN is using it, so this should have zero impact.
5076a392 3246
1e463951
FC
3247It attempted to provide an API to compile code down to an optree, but failed
3248to bind correctly to lexicals in the enclosing scope. It's not possible to
3249fix this problem within the constraints of its parameters and return value.
5076a392 3250
1e463951 3251=item C<find_rundefsvoffset>
5076a392 3252
1e463951
FC
3253The C<find_rundefsvoffset> function has been deprecated. It appeared that
3254its design was insufficient for reliably getting the lexical C<$_> at
3255run-time.
5076a392 3256
1e463951 3257Use the new C<find_rundefsv> function or the C<UNDERBAR> macro
cbb8c2bc
FC
3258instead. They directly return the right SV
3259representing C<$_>, whether it's
1e463951 3260lexical or dynamic.
5076a392 3261
1e463951 3262=item C<CALL_FPTR> and C<CPERLscope>
5076a392 3263
1e463951
FC
3264Those are left from an old implementation of C<MULTIPLICITY> using C++ objects,
3265which was removed in Perl 5.8. Nowadays these macros do exactly nothing, so
3266they shouldn't be used anymore.
5076a392 3267
1e463951
FC
3268For compatibility, they are still defined for external C<XS> code. Only
3269extensions defining C<PERL_CORE> must be updated now.
5076a392 3270
1e463951 3271=back
5076a392 3272
1e463951 3273=head2 Other Internal Changes
5076a392 3274
1e463951 3275=head3 Stack unwinding
5076a392 3276
1e463951
FC
3277The protocol for unwinding the C stack at the last stage of a C<die>
3278has changed how it identifies the target stack frame. This now uses
3279a separate variable C<PL_restartjmpenv>, where previously it relied on
3280the C<blk_eval.cur_top_env> pointer in the C<eval> context frame that
3281has nominally just been discarded. This change means that code running
3282during various stages of Perl-level unwinding no longer needs to take
3283care to avoid destroying the ghost frame.
5076a392 3284
1e463951 3285=head3 Scope stack entries
5076a392 3286
1e463951
FC
3287The format of entries on the scope stack has been changed, resulting in a
3288reduction of memory usage of about 10%. In particular, the memory used by
3289the scope stack to record each active lexical variable has been halved.
5076a392 3290
1e463951 3291=head3 Memory allocation for pointer tables
5076a392 3292
1e463951
FC
3293Memory allocation for pointer tables has been changed. Previously
3294C<Perl_ptr_table_store> allocated memory from the same arena system as
3295C<SV> bodies and C<HE>s, with freed memory remaining bound to those arenas
3296until interpreter exit. Now it allocates memory from arenas private to the
3297specific pointer table, and that memory is returned to the system when
3298C<Perl_ptr_table_free> is called. Additionally, allocation and release are
3299both less CPU intensive.
5076a392 3300
1e463951 3301=head3 C<UNDERBAR>
5076a392 3302
1e463951
FC
3303The C<UNDERBAR> macro now calls C<find_rundefsv>. C<dUNDERBAR> is now a
3304noop but should still be used to ensure past and future compatibility.
5076a392 3305
1e463951 3306=head3 String comparison routines renamed
5076a392 3307
1e463951
FC
3308The ibcmp_* functions have been renamed and are now called foldEQ,
3309foldEQ_locale and foldEQ_utf8. The old names are still available as
3310macros.
3311
3312=head3 C<chop> and C<chomp> implementations merged
3313
3314The opcode bodies for C<chop> and C<chomp> and for C<schop> and C<schomp>
3315have been merged. The implementation functions C<Perl_do_chop()> and
3316C<Perl_do_chomp()>, never part of the public API, have been merged and
3317moved to a static function in F<pp.c>. This shrinks the perl binary
3318slightly, and should not affect any code outside the core (unless it is
3319relying on the order of side effects when C<chomp> is passed a I<list> of
3320values).
5076a392
FC
3321
3322=head1 Selected Bug Fixes
3323
e8e35311
FC
3324=head2 I/O
3325
5076a392
FC
3326=over 4
3327
3328=item *
3329
e8e35311 3330Perl no longer produces this warning:
a593b319
FC
3331
3332 $ perl -we 'open my $f, ">", \my $x; binmode $f, "scalar"'
3333 Use of uninitialized value in binmode at -e line 1.
3334
3335=item *
3336
e8e35311
FC
3337Opening a glob reference via C<< open $fh, "E<gt>", \*glob >> will no longer
3338cause the glob to be corrupted when the filehandle is printed to. This would
3339cause perl to crash whenever the glob's contents were accessed
3340[perl #77492].
4ed2cea4
FC
3341
3342=item *
3343
e8e35311 3344PerlIO no longer crashes when called recursively, e.g., from a signal
cbb8c2bc 3345handler. Now it just leaks memory [perl #75556].
4ed2cea4
FC
3346
3347=item *
3348
e8e35311 3349Most I/O functions were not warning for unopened handles unless the
cbb8c2bc 3350'closed' and 'unopened' warnings categories were both enabled. Now only
e8e35311 3351C<use warnings 'unopened'> is necessary to trigger these warnings (as was
438c239f 3352always meant to be the case).
4ed2cea4
FC
3353
3354=item *
3355
438c239f 3356There have been several fixes to PerlIO layers:
e8e35311 3357
438c239f
FC
3358When C<binmode FH, ":crlf"> pushes the C<:crlf> layer on top of the stack,
3359it no longer enables crlf layers lower in the stack, to avoid unexpected
3360results [perl #38456].
4ed2cea4 3361
438c239f
FC
3362Opening a file in C<:raw> mode now does what it advertises to do (first
3363open the file, then binmode it), instead of simply leaving off the top
3364layer [perl #80764].
5076a392 3365
438c239f
FC
3366The three layers C<:pop>, C<:utf8> and C<:bytes> didn't allow stacking when
3367opening a file. For example
e8e35311 3368this:
5076a392 3369
e8e35311 3370 open FH, '>:pop:perlio', 'some.file' or die $!;
5076a392 3371
438c239f
FC
3372Would throw an error: "Invalid argument". This has been fixed in this
3373release [perl #82484].
5076a392 3374
e8e35311
FC
3375=back
3376
3377=head2 Regular Expression Bug Fixes
3378
3379=over
5076a392
FC
3380
3381=item *
3382
e8e35311
FC
3383The regular expression engine no longer loops when matching
3384C<"\N{LATIN SMALL LIGATURE FF}" =~ /f+/i> and similar expressions
cdc10f43 3385[perl #72998] (5.12.1).
5076a392
FC
3386
3387=item *
3388
e8e35311
FC
3389The trie runtime code should no longer allocate massive amounts of memory,
3390fixing #74484.
5076a392
FC
3391
3392=item *
3393
438c239f
FC
3394Syntax errors in C<< (?{...}) >> blocks no longer cause panic messages
3395[perl #2353].
5076a392
FC
3396
3397=item *
3398
438c239f
FC
3399A pattern like C<(?:(o){2})?> no longer causes a "panic" error
3400[perl #39233].
5076a392
FC
3401
3402=item *
3403
438c239f 3404A fatal error in regular expressions containing C<(.*?)> when processing
d430b8e7 3405UTF-8 data has been fixed [perl #75680] (5.12.2).
5076a392
FC
3406
3407=item *
3408
e8e35311 3409An erroneous regular expression engine optimisation that caused regex verbs like
438c239f 3410C<*COMMIT> sometimes to be ignored has been removed.
5076a392
FC
3411
3412=item *
3413
e8e35311
FC
3414The regular expression bracketed character class C<[\8\9]> was effectively the
3415same as C<[89\000]>, incorrectly matching a NULL character. It also gave
3416incorrect warnings that the C<8> and C<9> were ignored. Now C<[\8\9]> is the
3417same as C<[89]> and gives legitimate warnings that C<\8> and C<\9> are
3418unrecognized escape sequences, passed-through.
5076a392
FC
3419
3420=item *
3421
e8e35311
FC
3422A regular expression match in the right-hand side of a global substitution
3423(C<s///g>) that is in the same scope will no longer cause match variables
cbb8c2bc 3424to have the wrong values on subsequent iterations. This can happen when an
e8e35311
FC
3425array or hash subscript is interpolated in the right-hand side, as in
3426C<s|(.)|@a{ print($1), /./ }|g> [perl #19078].
5076a392
FC
3427
3428=item *
3429
438c239f
FC
3430Several cases in which characters in the Latin-1 non-ASCII range (0x80 to
34310xFF) used not to match themselves or used to match both a character class
3432and its complement have been fixed. For instance, U+00E2 could match both
3433C<\w> and C<\W> [perl #78464] [perl #18281] [perl #60156].
5076a392
FC
3434
3435=item *
3436
e8e35311
FC
3437Matching a Unicode character against an alternation containing characters
3438that happened to match continuation bytes in the former's UTF8
3439representation (C<qq{\x{30ab}} =~ /\xab|\xa9/>) would cause erroneous
3440warnings [perl #70998].
5076a392
FC
3441
3442=item *
3443
e8e35311
FC
3444The trie optimisation was not taking empty groups into account, preventing
3445'foo' from matching C</\A(?:(?:)foo|bar|zot)\z/> [perl #78356].
5076a392
FC
3446
3447=item *
3448
e8e35311
FC
3449A pattern containing a C<+> inside a lookahead would sometimes cause an
3450incorrect match failure in a global match (e.g., C</(?=(\S+))/g>)
3451[perl #68564].
5076a392
FC
3452
3453=item *
3454
e8e35311
FC
3455A regular expression optimisation would sometimes cause a match with a
3456C<{n,m}> quantifier to fail when it should match [perl #79152].
5076a392
FC
3457
3458=item *
3459
e8e35311 3460Case insensitive matching in regular expressions compiled under C<use
438c239f
FC
3461locale> now works much more sanely when the pattern or
3462target string is encoded internally in
3463UTF8. Previously, under these conditions the localeness
e8e35311
FC
3464was completely lost. Now, code points above 255 are treated as Unicode,
3465but code points between 0 and 255 are treated using the current locale
438c239f
FC
3466rules, regardless of whether the pattern or the string is encoded in UTF8.
3467The few case-insensitive matches that cross the 255/256 boundary are not
e8e35311
FC
3468allowed. For example, 0xFF does not caselessly match the character at
34690x178, LATIN CAPITAL LETTER Y WITH DIAERESIS, because 0xFF may not be
3470LATIN SMALL LETTER Y in the current locale, and Perl has no way of
3471knowing if that character even exists in the locale, much less what code
3472point it is.
5076a392
FC
3473
3474=item *
3475
e8e35311 3476The C<(?|...)> regular expression construct no longer crashes if the final
cbb8c2bc 3477branch has more sets of capturing parentheses than any other branch. This
e8e35311
FC
3478was fixed in Perl 5.10.1 for the case of a single branch, but that fix did
3479not take multiple branches into account [perl #84746].
5076a392
FC
3480
3481=item *
3482
e8e35311
FC
3483A bug has been fixed in the implementation of C<{...}> quantifiers in
3484regular expressions that prevented the code block in
3485C</((\w+)(?{ print $2 })){2}/> from seeing the C<$2> sometimes
3486[perl #84294].
5076a392 3487
e8e35311 3488=back
5076a392 3489
e8e35311
FC
3490=head2 Syntax/Parsing Bugs
3491
3492=over
5076a392
FC
3493
3494=item *
3495
e8e35311 3496C<when(scalar){...}> no longer crashes, but produces a syntax error
cdc10f43 3497[perl #74114] (5.12.1).
5076a392
FC
3498
3499=item *
3500
e8e35311
FC
3501A label right before a string eval (C<foo: eval $string>) no longer causes
3502the label to be associated also with the first statement inside the eval
3503[perl #74290] (5.12.1).
5076a392
FC
3504
3505=item *
3506
b2c076b5 3507The C<no 5.13.2;> form of C<no> no longer tries to turn on features or