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Correct the IPC::Cmd version in perldelta
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1=encoding utf8
2
3=head1 NAME
4
5076a392 5perldelta - what is new for perl v5.14.0
c71a852f 6
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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
43new name for U+0007 in Perl will be C<ALERT>, which corresponds nicely
44with the existing shorthand sequence for it, C<"\a">. C<\N{BEL}> will
45mean U+0007, with no warning given. The character at U+1F514 will not
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
375On Linux the legacy process name will be set with L<prctl(2)>, in
376addition to altering the POSIX name via C<argv[0]> as perl has done
377since version 4.000. Now system utilities that read the legacy process
378name such as ps, top and killall will recognize the name you set when
379assigning to C<$0>. The string you supply will be cut off at 16 bytes,
380this is a limitation imposed by Linux.
381
382=head3 C<srand()> now returns the seed
383
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384This allows programs that need to have repeatable results not to have to come
385up with their own seed-generating mechanism. Instead, they can use C<srand()>
386and stash the return value for future use. Typical is a test program which
1f539a1a 387has too many combinations to test comprehensively in the time available to it
e1b1739f 388each run. It can test a random subset each time and, should there be a failure,
1f539a1a 389log the seed used for that run so that it can later be used to reproduce the
e1b1739f 390same results.
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391
392=head3 printf-like functions understand post-1980 size modifiers
393
394Perl's printf and sprintf operators, and Perl's internal printf replacement
395function, now understand the C90 size modifiers "hh" (C<char>), "z"
396(C<size_t>), and "t" (C<ptrdiff_t>). Also, when compiled with a C99
397compiler, Perl now understands the size modifier "j" (C<intmax_t>).
398
399So, for example, on any modern machine, C<sprintf('%hhd', 257)> returns '1'.
400
401=head3 New global variable C<${^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
494convention has been enforced.
5076a392 495
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496Also, Perl no longer allows a tainted regular expression to invoke a
497user-defined. 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}> -
514C<\x{1FF}>, with no deprecation warning. Use of these values in the
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
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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
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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
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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
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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
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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>):
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570
571 use re qw(regexp_pattern);
572 my ($pat, $mods) = regexp_pattern($re_ref);
573
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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
592This was a bug, which has now been fixed. But it has the potential to break
593any code that was relying on it.
5076a392 594
61752d82 595=head2 Stashes and Package Variables
5076a392 596
61752d82 597=head3 Localised tied hashes and arrays are no longed tied
5076a392 598
61752d82 599In the following:
5076a392 600
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601 tie @a, ...;
602 {
603 local @a;
604 # here, @a is a now a new, untied array
605 }
606 # here, @a refers again to the old, tied array
5076a392 607
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608The new local array used to be made tied too, which was fairly pointless,
609and has now been fixed. This fix could however potentially cause a change
610in behaviour of some code.
5076a392 611
61752d82 612=head3 Stashes are now always defined
5076a392 613
61752d82
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614C<defined %Foo::> now always returns true, even when no symbols have yet been
615defined in that package.
5076a392 616
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617This is a side effect of removing a special case kludge in the tokeniser,
618added for 5.10.0, to hide side effects of changes to the internal storage of
619hashes that drastically reduce their memory usage overhead.
620
621Calling defined on a stash has been deprecated since 5.6.0, warned on
622lexicals since 5.6.0, and warned for stashes (and other package
623variables) since 5.12.0. C<defined %hash> has always exposed an
624implementation detail - emptying a hash by deleting all entries from it does
625not make C<defined %hash> false, hence C<defined %hash> is not valid code to
626determine whether an arbitrary hash is empty. Instead, use the behaviour
627that an empty C<%hash> always returns false in a scalar context.
628
629=head3 Dereferencing typeglobs
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630
631If you assign a typeglob to a scalar variable:
632
633 $glob = *foo;
634
635the glob that is copied to C<$glob> is marked with a special flag
636indicating that the glob is just a copy. This allows subsequent assignments
637to C<$glob> to overwrite the glob. The original glob, however, is
638immutable.
639
640Many Perl operators did not distinguish between these two types of globs.
641This would result in strange behaviour in edge cases: C<untie $scalar>
642would do nothing if the last thing assigned to the scalar was a glob
643(because it treated it as C<untie *$scalar>, which unties a handle).
f318e2e6 644Assignment to a glob slot (e.g., C<*$glob = \@some_array>) would simply
5076a392
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645assign C<\@some_array> to C<$glob>.
646
647To fix this, the C<*{}> operator (including the C<*foo> and C<*$foo> forms)
648has been modified to make a new immutable glob if its operand is a glob
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FC
649copy. This allows operators that make a distinction between globs and
650scalars to be modified to treat only immutable globs as globs. (C<tie>,
651C<tied> and C<untie> have been left as they are for compatibility's sake,
61752d82 652but will warn. See L</Deprecations>.)
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653
654This causes an incompatible change in code that assigns a glob to the
655return value of C<*{}> when that operator was passed a glob copy. Take the
656following code, for instance:
657
658 $glob = *foo;
659 *$glob = *bar;
660
661The C<*$glob> on the second line returns a new immutable glob. That new
662glob is made an alias to C<*bar>. Then it is discarded. So the second
663assignment has no effect.
664
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665See L<http://rt.perl.org/rt3/Public/Bug/Display.html?id=77810> for even
666more detail.
667
61752d82 668=head3 Clearing stashes
5076a392
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669
670Stash list assignment C<%foo:: = ()> used to make the stash anonymous
671temporarily while it was being emptied. Consequently, any of its
672subroutines referenced elsewhere would become anonymous (showing up as
673"(unknown)" in C<caller>). Now they retain their package names, such that
674C<caller> will return the original sub name if there is still a reference
675to its typeglob, or "foo::__ANON__" otherwise [perl #79208].
676
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677=head3 Magic variables outside the main package
678
679In previous versions of Perl, magic variables like C<$!>, C<%SIG>, etc. would
680'leak' into other packages. So C<%foo::SIG> could be used to access signals,
681C<${"foo::!"}> (with strict mode off) to access C's C<errno>, etc.
682
683This was a bug, or an 'unintentional' feature, which caused various ill effects,
684such as signal handlers being wiped when modules were loaded, etc.
685
686This has been fixed (or the feature has been removed, depending on how you see
687it).
688
689=head2 Changes to Syntax or to Perl Operators
690
691=head3 C<given> return values
692
693C<given> blocks now return the last evaluated
694expression, or an empty list if the block was exited by C<break>. Thus you
695can now write:
696
697 my $type = do {
698 given ($num) {
699 break when undef;
700 'integer' when /^[+-]?[0-9]+$/;
701 'float' when /^[+-]?[0-9]+(?:\.[0-9]+)?$/;
702 'unknown';
703 }
704 };
705
706See L<perlsyn/Return value> for details.
707
708=head3 Change in the parsing of certain prototypes
709
710Functions declared with the following prototypes now behave correctly as unary
711functions:
712
713 *
714 \$ \% \@ \* \&
715 \[...]
716 ;$ ;*
717 ;\$ ;\% etc.
718 ;\[...]
719
720Due to this bug fix [perl #75904], functions
721using the C<(*)>, C<(;$)> and C<(;*)> prototypes
722are parsed with higher precedence than before. So in the following example:
723
724 sub foo($);
725 foo $a < $b;
726
727the second line is now parsed correctly as C<< foo($a) < $b >>, rather than
728C<< foo($a < $b) >>. This happens when one of these operators is used in
729an unparenthesised argument:
730
731 < > <= >= lt gt le ge
732 == != <=> eq ne cmp ~~
733 &
734 | ^
735 &&
736 || //
737 .. ...
738 ?:
739 = += -= *= etc.
740
741=head3 Smart-matching against array slices
742
743Previously, the following code resulted in a successful match:
744
745 my @a = qw(a y0 z);
746 my @b = qw(a x0 z);
747 @a[0 .. $#b] ~~ @b;
748
749This odd behaviour has now been fixed [perl #77468].
750
751=head3 Negation treats strings differently from before
752
753The unary negation operator C<-> now treats strings that look like numbers
754as numbers [perl #57706].
755
756=head3 Negative zero
757
758Negative zero (-0.0), when converted to a string, now becomes "0" on all
759platforms. It used to become "-0" on some, but "0" on others.
760
761If you still need to determine whether a zero is negative, use
762C<sprintf("%g", $zero) =~ /^-/> or the L<Data::Float> module on CPAN.
763
764=head3 C<:=> is now a syntax error
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765
766Previously C<my $pi := 4;> was exactly equivalent to C<my $pi : = 4;>,
767with the C<:> being treated as the start of an attribute list, ending before
768the C<=>. The use of C<:=> to mean C<: => was deprecated in 5.12.0, and is now
769a syntax error. This will allow the future use of C<:=> as a new token.
770
771We find no Perl 5 code on CPAN using this construction, outside the core's
772tests for it, so we believe that this change will have very little impact on
773real-world codebases.
774
775If it is absolutely necessary to have empty attribute lists (for example,
776because of a code generator) then avoid the error by adding a space before
777the C<=>.
778
61752d82 779=head2 Threads and Processes
5076a392 780
61752d82 781=head3 Directory handles not copied to threads
5076a392 782
61752d82
FC
783On systems other than Windows that do not have
784a C<fchdir> function, newly-created threads no
785longer inherit directory handles from their parent threads. Such programs
786would usually have crashed anyway [perl #75154].
5076a392 787
61752d82 788=head3 C<close> on shared pipes
5076a392 789
61752d82
FC
790The C<close> function no longer waits for the child process to exit if the
791underlying file descriptor is still in use by another thread, to avoid
792deadlocks. It returns true in such cases.
5076a392 793
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FC
794=head3 fork() emulation will not wait for signalled children
795
796On Windows parent processes would not terminate until all forked
797childred had terminated first. However, C<kill('KILL', ...)> is
798inherently unstable on pseudo-processes, and C<kill('TERM', ...)>
799might not get delivered if the child if blocked in a system call.
800
801To avoid the deadlock and still provide a safe mechanism to terminate
802the hosting process, Perl will now no longer wait for children that
803have been sent a SIGTERM signal. It is up to the parent process to
804waitpid() for these children if child clean-up processing must be
805allowed to finish. However, it is also the responsibility of the
806parent then to avoid the deadlock by making sure the child process
807can't be blocked on I/O either.
808
809See L<perlfork> for more information about the fork() emulation on
810Windows.
811
61752d82 812=head2 Configuration
5076a392 813
61752d82 814=head3 Naming fixes in Policy_sh.SH may invalidate Policy.sh
5076a392 815
61752d82
FC
816Several long-standing typos and naming confusions in Policy_sh.SH have
817been fixed, standardizing on the variable names used in config.sh.
5076a392 818
61752d82
FC
819This will change the behavior of Policy.sh if you happen to have been
820accidentally relying on the Policy.sh incorrect behavior.
f318e2e6 821
5a1f7719
FC
822=head3 Perl source code is read in text mode on Windows
823
824Perl scripts used to be read in binary mode on Windows for the benefit
825of the ByteLoader module (which is no longer part of core Perl). This
826had the side effect of breaking various operations on the DATA filehandle,
827including seek()/tell(), and even simply reading from DATA after file handles
828have been flushed by a call to system(), backticks, fork() etc.
829
830The default build options for Windows have been changed to read Perl source
831code on Windows in text mode now. Hopefully ByteLoader will be updated on
832CPAN to automatically handle this situation [perl #28106].
833
5076a392
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834=head1 Deprecations
835
1e463951
FC
836See also L</Deprecated C APIs>.
837
5076a392
FC
838=head2 Omitting a space between a regular expression and subsequent word
839
18139a1b
FC
840Omitting a space between a regular expression operator or
841its modifiers and the following word is deprecated. For
842example, C<< m/foo/sand $bar >> will still be parsed
843as C<< m/foo/s and $bar >> but will issue a warning.
5076a392 844
e683df94
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845=head2 C<\cI<X>>
846
847The backslash-c construct was designed as a way of specifying
848non-printable characters, but there were no restrictions (on ASCII
849platforms) on what the character following the C<c> could be. Now,
850a deprecation warning is raised if that character isn't an ASCII character.
851Also, a deprecation warning is raised for C<"\c{"> (which is the same
852as simply saying C<";">).
853
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854=head2 C<"\b{"> and C<"\B{">
855
856In regular expressions, a literal C<"{"> immediately following a C<"\b">
857(not in a bracketed character class) or a C<"\B{"> is now deprecated
858to allow for its future use by Perl itself.
859
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860=head2 Deprecation warning added for deprecated-in-core .pl libs
861
862This is a mandatory warning, not obeying -X or lexical warning bits.
863The warning is modelled on that supplied by deprecate.pm for
864deprecated-in-core .pm libraries. It points to the specific CPAN
823d0e46
FC
865distribution that contains the .pl libraries. The CPAN version, of
866course, does not generate the warning.
5076a392
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867
868=head2 List assignment to C<$[>
869
823d0e46
FC
870Assignment to C<$[> was deprecated and started to give warnings in
871Perl version 5.12.0. This version of perl also starts to emit a warning when
872assigning to C<$[> in list context. This fixes an oversight in 5.12.0.
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873
874=head2 Use of qw(...) as parentheses
875
876Historically the parser fooled itself into thinking that C<qw(...)> literals
877were always enclosed in parentheses, and as a result you could sometimes omit
878parentheses around them:
879
880 for $x qw(a b c) { ... }
881
882The parser no longer lies to itself in this way. Wrap the list literal in
823d0e46 883parentheses, like this:
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884
885 for $x (qw(a b c)) { ... }
886
887=head2 C<\N{BELL}> is deprecated
888
889This is because Unicode is using that name for a different character.
890See L</Unicode Version 6.0 is now supported (mostly)> for more
891explanation.
892
893=head2 C<?PATTERN?> is deprecated
894
895C<?PATTERN?> (without the initial m) has been deprecated and now produces
896a warning. This is to allow future use of C<?> in new operators.
897The match-once functionality is still available in the form of C<m?PATTERN?>.
898
5076a392
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899=head2 Tie functions on scalars holding typeglobs
900
901Calling a tie function (C<tie>, C<tied>, C<untie>) with a scalar argument
902acts on a file handle if the scalar happens to hold a typeglob.
903
904This is a long-standing bug that will be removed in Perl 5.16, as
905there is currently no way to tie the scalar itself when it holds
906a typeglob, and no way to untie a scalar that has had a typeglob
907assigned to it.
908
823d0e46 909Now there is a deprecation warning whenever a tie
5076a392
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910function is used on a handle without an explicit C<*>.
911
18139a1b 912=head2 User-defined case-mapping
5076a392 913
18139a1b
FC
914This feature is being deprecated due to its many issues, as documented in
915L<perlunicode/User-Defined Case Mappings (for serious hackers only)>.
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916It is planned to remove this feature in Perl 5.16. Instead use the CPAN module
917L<Unicode::Casing>, which provides improved functionality.
823d0e46 918
18139a1b 919=head2 Deprecated modules
5076a392
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920
921The following modules will be removed from the core distribution in a
922future release, and should be installed from CPAN instead. Distributions
923on CPAN which require these should add them to their prerequisites. The
823d0e46 924core versions of these modules will issue a deprecation warning.
5076a392
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925
926If you ship a packaged version of Perl, either alone or as part of a
927larger system, then you should carefully consider the repercussions of
823d0e46 928core module deprecations. You may want to consider shipping your default
5076a392 929build of Perl with packages for some or all deprecated modules which
823d0e46 930install into C<vendor> or C<site> perl library directories. This will
5076a392
FC
931inhibit the deprecation warnings.
932
933Alternatively, you may want to consider patching F<lib/deprecate.pm>
934to provide deprecation warnings specific to your packaging system
935or distribution of Perl, consistent with how your packaging system
936or distribution manages a staged transition from a release where the
937installation of a single package provides the given functionality, to
938a later release where the system administrator needs to know to install
939multiple packages to get that same functionality.
940
941You can silence these deprecation warnings by installing the modules
942in question from CPAN. To install the latest version of all of them,
943just install C<Task::Deprecations::5_14>.
944
945=over
946
947=item L<Devel::DProf>
948
949We strongly recommend that you install and used L<Devel::NYTProf> in
950preference, as it offers significantly improved profiling and reporting.
951
952=back
953
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954=head1 Performance Enhancements
955
54c7bb16 956=head2 "Safe signals" optimisation
df91d470
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957
958Signal dispatch has been moved from the runloop into control ops. This
959should give a few percent speed increase, and eliminates almost all of
960the speed penalty caused by the introduction of "safe signals" in
9615.8.0. Signals should still be dispatched within the same statement as
962they were previously - if this is not the case, or it is possible to
963create uninterruptible loops, this is a bug, and reports are encouraged
964of how to recreate such issues.
965
54c7bb16 966=head2 Optimisation of shift; and pop; calls without arguments
df91d470 967
111b6aa7
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968Two fewer OPs are used for shift and pop calls with no argument (with
969implicit C<@_>). This change makes C<shift;> 5% faster than C<shift @_;>
970on non-threaded perls and 25% faster on threaded.
df91d470 971
fa232254 972=head2 Optimisation of regexp engine string comparison work
df91d470 973
fa232254
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974The foldEQ_utf8 API function for case-insensitive comparison of strings (which
975is used heavily by the regexp engine) was substantially refactored and
976optimised - and its documentation much improved as a free bonus gift.
df91d470 977
fa232254 978=head2 Regular expression compilation speed-up
df91d470 979
fa232254
FC
980Compiling regular expressions has been made faster for the case where upgrading
981the regex to utf8 is necessary but that isn't known when the compilation begins.
df91d470 982
fa232254 983=head2 String appending is 100 times faster
df91d470 984
fa232254
FC
985When doing a lot of string appending, perl could end up allocating a lot more
986memory than needed in a very inefficient way, if perl was configured to use the
987system's C<malloc> implementation instead of its own.
988
989C<sv_grow>, which is what's being used to allocate more memory if necessary
990when appending to a string, has now been taught how to round up the memory
991it requests to a certain geometric progression, making it much faster on
992certain platforms and configurations. On Win32, it's now about 100 times
993faster.
994
995=head2 Eliminate C<PL_*> accessor functions under ithreads
996
997When C<MULTIPLICITY> was first developed, and interpreter state moved into
998an interpreter struct, thread and interpreter local C<PL_*> variables were
999defined as macros that called accessor functions, returning the address of
1000the value, outside of the perl core. The intent was to allow members
1001within the interpreter struct to change size without breaking binary
1002compatibility, so that bug fixes could be merged to a maintenance branch
1003that necessitated such a size change.
1004
1005However, some non-core code defines C<PERL_CORE>, sometimes intentionally
1006to bypass this mechanism for speed reasons, sometimes for other reasons but
1007with the inadvertent side effect of bypassing this mechanism. As some of
1008this code is widespread in production use, the result is that the core
1009I<can't> change the size of members of the interpreter struct, as it will
1010break such modules compiled against a previous release on that maintenance
1011branch. The upshot is that this mechanism is redundant, and well-behaved
1012code is penalised by it. Hence it can and should be removed (and has
1013been).
1014
1015=head2 Freeing weak references
1016
1017When an object has many weak references to it, freeing that object
1018can under some some circumstances take O(N^2) time to free (where N is the
1019number of references). The number of circumstances has been reduced
1020[perl #75254]
1021
1022=head2 Lexical array and hash assignments
1023
1024An earlier optimisation to speed up C<my @array = ...> and
1025C<my %hash = ...> assignments caused a bug and was disabled in Perl 5.12.0.
1026
1027Now we have found another way to speed up these assignments [perl #82110].
df91d470 1028
111b6aa7 1029=head2 C<@_> uses less memory
df91d470 1030
111b6aa7
FC
1031Previously, C<@_> was allocated for every subroutine at compile time with
1032enough space for four entries. Now this allocation is done on demand when
1033the subroutine is called [perl #72416].
5076a392 1034
5076a392
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1035=head2 Size optimisations to SV and HV structures
1036
1037xhv_fill has been eliminated from struct xpvhv, saving 1 IV per hash and
111b6aa7 1038on some systems will cause struct xpvhv to become cache-aligned. To avoid
5076a392
FC
1039this memory saving causing a slowdown elsewhere, boolean use of HvFILL
1040now calls HvTOTALKEYS instead (which is equivalent) - so while the fill
111b6aa7
FC
1041data when actually required are now calculated on demand, the cases when
1042this needs to be done should be few and far between.
5076a392 1043
111b6aa7
FC
1044The order of structure elements in SV bodies has changed. Effectively,
1045the NV slot has swapped location with STASH and MAGIC. As all access to
1046SV members is via macros, this should be completely transparent. This
5076a392
FC
1047change allows the space saving for PVHVs documented above, and may reduce
1048the memory allocation needed for PVIVs on some architectures.
1049
fa232254
FC
1050C<XPV>, C<XPVIV>, and C<XPVNV> now only allocate the parts of the C<SV> body
1051they actually use, saving some space.
5076a392 1052
fa232254
FC
1053Scalars containing regular expressions now only allocate the part of the C<SV>
1054body they actually use, saving some space.
5076a392
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1055
1056=head2 Memory consumption improvements to Exporter
1057
1058The @EXPORT_FAIL AV is no longer created unless required, hence neither is
111b6aa7
FC
1059the typeglob backing it. This saves about 200 bytes for every package that
1060uses Exporter but doesn't use this functionality.
5076a392 1061
111b6aa7 1062=head2 Memory savings for weak references
5076a392
FC
1063
1064For weak references, the common case of just a single weak reference per
1065referent has been optimised to reduce the storage required. In this case it
111b6aa7 1066saves the equivalent of one small Perl array per referent.
5076a392 1067
111b6aa7 1068=head2 C<%+> and C<%-> use less memory
5076a392
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1069
1070The bulk of the C<Tie::Hash::NamedCapture> module used to be in the perl
111b6aa7 1071core. It has now been moved to an XS module, to reduce the overhead for
5076a392
FC
1072programs that do not use C<%+> or C<%->.
1073
fa232254 1074=head2 Multiple small improvements to threads
5076a392 1075
fa232254
FC
1076The internal structures of threading now make fewer API calls and fewer
1077allocations, resulting in noticeably smaller object code. Additionally,
1078many thread context checks have been deferred so that they're only done
1079when required (although this is only possible for non-debugging builds).
5076a392 1080
fa232254 1081=head2 Adjacent pairs of nextstate opcodes are now optimized away
5076a392 1082
fa232254 1083Previously, in code such as
5076a392 1084
fa232254 1085 use constant DEBUG => 0;
5076a392 1086
fa232254
FC
1087 sub GAK {
1088 warn if DEBUG;
1089 print "stuff\n";
1090 }
5076a392 1091
fa232254
FC
1092the ops for C<warn if DEBUG;> would be folded to a C<null> op (C<ex-const>), but
1093the C<nextstate> op would remain, resulting in a runtime op dispatch of
1094C<nextstate>, C<nextstate>, ....
5076a392 1095
fa232254
FC
1096The execution of a sequence of C<nextstate> ops is indistinguishable from just
1097the last C<nextstate> op so the peephole optimizer now eliminates the first of
1098a pair of C<nextstate> ops, except where the first carries a label, since labels
1099must not be eliminated by the optimizer and label usage isn't conclusively known
1100at compile time.
5076a392
FC
1101
1102=head1 Modules and Pragmata
1103
1104=head2 New Modules and Pragmata
1105
1106=over 4
1107
1108=item *
1109
1110C<CPAN::Meta::YAML> 0.003 has been added as a dual-life module. It supports a
1111subset of YAML sufficient for reading and writing META.yml and MYMETA.yml files
1112included with CPAN distributions or generated by the module installation
1113toolchain. It should not be used for any other general YAML parsing or
1114generation task.
1115
1116=item *
1117
1118C<CPAN::Meta> version 2.110440 has been added as a dual-life module. It
1119provides a standard library to read, interpret and write CPAN distribution
1120metadata files (e.g. META.json and META.yml) which describes a
1121distribution, its contents, and the requirements for building it and
1122installing it. The latest CPAN distribution metadata specification is
1123included as C<CPAN::Meta::Spec> and notes on changes in the specification
1124over time are given in C<CPAN::Meta::History>.
1125
1126=item *
1127
5a553547 1128C<HTTP::Tiny> 0.011 has been added as a dual-life module. It is a very
5076a392
FC
1129small, simple HTTP/1.1 client designed for simple GET requests and file
1130mirroring. It has has been added to enable CPAN.pm and CPANPLUS to
1131"bootstrap" HTTP access to CPAN using pure Perl without relying on external
1132binaries like F<curl> or F<wget>.
1133
1134=item *
1135
1136C<JSON::PP> 2.27105 has been added as a dual-life module, for the sake of
1137reading F<META.json> files in CPAN distributions.
1138
1139=item *
1140
21ef4e45 1141C<Module::Metadata> 1.000004 has been added as a dual-life module. It gathers
5076a392
FC
1142package and POD information from Perl module files. It is a standalone module
1143based on Module::Build::ModuleInfo for use by other module installation
1144toolchain components. Module::Build::ModuleInfo has been deprecated in
1145favor of this module instead.
1146
1147=item *
1148
1149C<Perl::OSType> 1.002 has been added as a dual-life module. It maps Perl
1150operating system names (e.g. 'dragonfly' or 'MSWin32') to more generic types
1151with standardized names (e.g. "Unix" or "Windows"). It has been refactored
1152out of Module::Build and ExtUtils::CBuilder and consolidates such mappings into
1153a single location for easier maintenance.
1154
1155=item *
1156
1157The following modules were added by the C<Unicode::Collate>
1158upgrade. See below for details.
1159
1160C<Unicode::Collate::CJK::Big5>
1161
1162C<Unicode::Collate::CJK::GB2312>
1163
1164C<Unicode::Collate::CJK::JISX0208>
1165
1166C<Unicode::Collate::CJK::Korean>
1167
1168C<Unicode::Collate::CJK::Pinyin>
1169
1170C<Unicode::Collate::CJK::Stroke>
1171
1172=item *
1173
1174C<Version::Requirements> version 0.101020 has been added as a dual-life
1175module. It provides a standard library to model and manipulates module
1176prerequisites and version constraints as defined in the L<CPAN::Meta::Spec>.
1177
1178=back
1179
a5794e94 1180=head2 Updated Modules and Pragma
5076a392
FC
1181
1182=over 4
1183
1184=item *
1185
5076a392
FC
1186C<Archive::Extract> has been upgraded from version 0.38 to 0.48.
1187
1188Updates since 0.38 include: a safe print method that guards
1189Archive::Extract from changes to $\; a fix to the tests when run in core
1984204c
FC
1190perl; support for TZ files; a modification for the lzma
1191logic to favour IO::Uncompress::Unlzma; and a fix
1192for an issue with NetBSD-current and its new unzip
5076a392
FC
1193executable.
1194
1195=item *
1196
1197C<Archive::Tar> has been upgraded from version 1.54 to 1.76.
1198
1984204c
FC
1199Important changes since 1.54 include the following:
1200
1201=over
1202
1203=item *
1204
1205Compatibility with busybox implementations of tar
1206
1207=item *
1208
1209A fix so that C<write()> and C<create_archive()>
1210close only handles they opened
1211
1212=item *
1213
1214A bug was fixed regarding the exit code of extract_archive.
5076a392 1215
1984204c
FC
1216=item *
1217
4f978a3b 1218The C<ptar> utility has a new option to allow safe
5076a392
FC
1219creation of tarballs without world-writable files on Windows, allowing those
1220archives to be uploaded to CPAN.
1221
1984204c
FC
1222=item *
1223
1224A new ptargrep utility for using regular expressions against
5076a392
FC
1225the contents of files in a tar archive.
1226
1984204c
FC
1227=item *
1228
1229Pax extended headers are now skipped.
1230
1231=back
5076a392
FC
1232
1233=item *
1234
5076a392
FC
1235C<B> has been upgraded from version 1.23 to 1.27.
1236
1237It no longer crashes when taking apart a C<y///> containing characters
1238outside the octet range or compiled in a C<use utf8> scope.
1239
1240The size of the shared object has been reduced by about 40%, with no
1241reduction in functionality.
1242
1243=item *
1244
1245C<B::Concise> has been upgraded from version 0.78 to 0.82.
1246
1247B::Concise marks rv2sv, rv2av and rv2hv ops with the new OPpDEREF flag
1248as "DREFed".
1249
1250It no longer produces mangled output with the C<-tree> option
1251[perl #80632].
1252
1253=item *
1254
5076a392
FC
1255C<B::Deparse> has been upgraded from version 0.96 to 1.02.
1256
1984204c 1257The deparsing of a nextstate op has changed when it has both a
5076a392
FC
1258change of package (relative to the previous nextstate), or a change of
1259C<%^H> or other state, and a label. Previously the label was emitted
cdc10f43 1260first, but now the label is emitted last (5.12.1).
5076a392 1261
5a553547
FC
1262The C<no 5.13.2> or similar form is now correctly handled by B::Deparse
1263(5.12.3).
5076a392
FC
1264
1265B::Deparse now properly handles the code that applies a conditional
1266pattern match against implicit C<$_> as it was fixed in [perl #20444].
1267
1984204c
FC
1268Deparsing of C<our> followed by a variable with funny characters
1269(as permitted under the C<utf8> pragma) has also been fixed [perl #33752].
5076a392
FC
1270
1271=item *
1272
d430b8e7 1273C<Carp> has been upgraded from version 1.15 to 1.19.
5076a392
FC
1274
1275L<Carp> now detects incomplete L<caller()|perlfunc/"caller EXPR"> overrides and
d430b8e7
FC
1276avoids using bogus C<@DB::args>. To provide backtraces,
1277Carp relies on particular behaviour of the C<caller>
1278built-in. Carp now detects if other code has
5076a392 1279overridden this with an incomplete implementation, and modifies its backtrace
d430b8e7
FC
1280accordingly. Previously incomplete overrides would cause incorrect values
1281in backtraces (best case), or obscure fatal errors (worst case).
5076a392
FC
1282
1283This fixes certain cases of C<Bizarre copy of ARRAY> caused by modules
d430b8e7 1284overriding C<caller()> incorrectly (5.12.2).
5076a392 1285
1984204c 1286It now also avoids using regular expressions that cause perl to
5076a392
FC
1287load its Unicode tables, in order to avoid the 'BEGIN not safe after
1288errors' error that will ensue if there has been a syntax error
1289[perl #82854].
1290
1291=item *
1292
1293C<CGI> has been upgraded from version 3.48 to 3.51.
1294
1295This provides the following security fixes: the MIME boundary in
1984204c
FC
1296multipart_init is now random and the handling of
1297newlines embedded in header values has been improved.
5076a392
FC
1298
1299=item *
1300
5076a392
FC
1301C<Compress::Raw::Bzip2> has been upgraded from version 2.024 to 2.033.
1302
1984204c 1303It has been updated to use bzip2 1.0.6.
5076a392
FC
1304
1305=item *
1306
f75b7efc 1307C<CPAN> has been upgraded from version 1.94_56 to 1.9600.
1984204c
FC
1308
1309Major highlights:
5076a392
FC
1310
1311=over 4
1312
1984204c 1313=item * much less configuration dialog hassle
5076a392 1314
1984204c 1315=item * support for META/MYMETA.json
5076a392 1316
1984204c 1317=item * support for local::lib
5076a392 1318
1984204c 1319=item * support for HTTP::Tiny to reduce the dependency on ftp sites
5076a392 1320
1984204c 1321=item * automatic mirror selection
5076a392 1322
1984204c 1323=item * iron out all known bugs in configure_requires
5076a392 1324
1984204c
FC
1325=item * support for distributions compressed with bzip2
1326
1327=item * allow Foo/Bar.pm on the commandline to mean Foo::Bar
1328
1329=back
5076a392
FC
1330
1331=item *
1332
d430b8e7
FC
1333C<CPANPLUS> has been upgraded from version 0.90 to 0.9103.
1334
1335A change to F<cpanp-run-perl>
1336resolves L<RT #55964|http://rt.cpan.org/Public/Bug/Display.html?id=55964>
1337and L<RT #57106|http://rt.cpan.org/Public/Bug/Display.html?id=57106>, both
1338of which related to failures to install distributions that use
1339C<Module::Install::DSL> (5.12.2).
5076a392 1340
1984204c
FC
1341A dependency on Config was not recognised as a
1342core module dependency. This has been fixed.
5076a392 1343
1984204c 1344CPANPLUS now includes support for META.json and MYMETA.json.
5076a392
FC
1345
1346=item *
1347
5076a392
FC
1348C<Data::Dumper> has been upgraded from version 2.125 to 2.130_02.
1349
4ed2cea4
FC
1350The indentation used to be off when C<$Data::Dumper::Terse> was set. This
1351has been fixed [perl #73604].
1352
1984204c
FC
1353This upgrade also fixes a crash when using custom sort functions that might
1354cause the stack to change [perl #74170].
5076a392
FC
1355
1356C<Dumpxs> no longer crashes with globs returned by C<*$io_ref>
1357[perl #72332].
1358
1359=item *
1360
5076a392
FC
1361C<Devel::DProf> has been upgraded from version 20080331.00 to 20110228.00.
1362
1363Merely loading C<Devel::DProf> now no longer triggers profiling to start.
1364C<use Devel::DProf> and C<perl -d:DProf ...> still behave as before and start
1365the profiler.
1366
1367NOTE: C<Devel::DProf> is deprecated and will be removed from a future
1984204c 1368version of Perl. We strongly recommend that you install and use
5076a392
FC
1369L<Devel::NYTProf> instead, as it offers significantly improved
1370profiling and reporting.
1371
1372=item *
1373
5076a392
FC
1374C<diagnostics> has been upgraded from version 1.19 to 1.22.
1375
1376It now renders pod links slightly better, and has been taught to find
1377descriptions for messages that share their descriptions with other
1378messages.
1379
1380=item *
1381
1382C<Digest::MD5> has been upgraded from version 2.39 to 2.51.
1383
1384It is now safe to use this module in combination with threads.
1385
1386=item *
1387
1388C<Digest::SHA> has been upgraded from version 5.47 to 5.61.
1389
1390C<shasum> now more closely mimics C<sha1sum>/C<md5sum>.
1391
1392C<Addfile> accepts all POSIX filenames.
1393
1984204c
FC
1394New SHA-512/224 and SHA-512/256 transforms (ref. NIST Draft FIPS 180-4
1395[February 2011])
5076a392
FC
1396
1397=item *
1398
5076a392
FC
1399C<DynaLoader> has been upgraded from version 1.10 to 1.12.
1400
1401It fixes a buffer overflow when passed a very long file name.
1402
1403It no longer inherits from AutoLoader; hence it no longer
1404produces weird error messages for unsuccessful method calls on classes that
1405inherit from DynaLoader [perl #84358].
1406
1407=item *
1408
1409C<Encode> has been upgraded from version 2.39 to 2.42.
1410
1411Now, all 66 Unicode non-characters are treated the same way U+FFFF has
1984204c
FC
1412always been treated; in cases when it was disallowed, all 66 are
1413disallowed; in those cases where it warned, all 66 warn.
5076a392
FC
1414
1415=item *
1416
5076a392
FC
1417C<Errno> has been upgraded from version 1.11 to 1.13.
1418
1419The implementation of C<Errno> has been refactored to use about 55% less memory.
5076a392
FC
1420
1421On some platforms with unusual header files, like Win32/gcc using mingw64
1422headers, some constants which weren't actually error numbers have been exposed
1423by C<Errno>. This has been fixed [perl #77416].
1424
1425=item *
1426
1427C<Exporter> has been upgraded from version 5.64_01 to 5.64_03.
1428
1429Exporter no longer overrides C<$SIG{__WARN__}> [perl #74472]
1430
1431=item *
1432
5076a392
FC
1433C<ExtUtils::Constant> has been upgraded from 0.22 to 0.23.
1434
1435The C<AUTOLOAD> helper code generated by C<ExtUtils::Constant::ProxySubs>
1436can now C<croak> for missing constants, or generate a complete C<AUTOLOAD>
1984204c
FC
1437subroutine in XS, allowing simplification of many modules that use it
1438(C<Fcntl>, C<File::Glob>, C<GDBM_File>, C<I18N::Langinfo>, C<POSIX>,
1439C<Socket>).
5076a392
FC
1440
1441C<ExtUtils::Constant::ProxySubs> can now optionally push the names of all
1984204c 1442constants onto the package's C<@EXPORT_OK>.
5076a392
FC
1443
1444=item *
1445
5076a392
FC
1446C<File::DosGlob> has been upgraded from version 1.01 to 1.03.
1447
1448It allows patterns containing literal parentheses (they no longer need to
1984204c
FC
1449be escaped). On Windows, it no longer
1450adds an extra F<./> to the file names
5076a392
FC
1451returned when the pattern is a relative glob with a drive specification,
1452like F<c:*.pl> [perl #71712].
1453
1454=item *
1455
1456C<File::Fetch> has been upgraded from version 0.24 to 0.32.
1457
1458C<HTTP::Lite> is now supported for 'http' scheme.
1459
1460The C<fetch> utility is supported on FreeBSD, NetBSD and
1461Dragonfly BSD for the C<http> and C<ftp> schemes.
1462
1463=item *
1464
1465C<File::Find> has been upgraded from version 1.15 to 1.18.
1466
1984204c 1467It improves handling of backslashes on Windows, so that paths like
5076a392
FC
1468F<c:\dir\/file> are no longer generated [perl #71710].
1469
1470=item *
1471
d430b8e7
FC
1472C<File::Spec> has been upgraded from version 3.31 to 3.33.
1473
1474Several portability fixes were made in C<File::Spec::VMS>: a colon is now
1475recognized as a delimiter in native filespecs; caret-escaped delimiters are
1476recognized for better handling of extended filespecs; C<catpath()> returns
1477an empty directory rather than the current directory if the input directory
1478name is empty; C<abs2rel()> properly handles Unix-style input (5.12.2).
1479
1480=item *
1481
5076a392
FC
1482C<File::stat> has been upgraded from 1.02 to 1.04.
1483
1484The C<-x> and C<-X> file test operators now work correctly under the root
1485user.
1486
1487=item *
1488
5076a392
FC
1489C<GDBM_File> has been upgraded from 1.10 to 1.13.
1490
1491This fixes a memory leak when DBM filters are used.
1492
1493=item *
1494
1495C<Hash::Util> has been upgraded from 0.07 to 0.10.
1496
1984204c
FC
1497Hash::Util no longer emits spurious "uninitialized" warnings when
1498recursively locking hashes that have undefined values [perl #74280].
5076a392
FC
1499
1500=item *
1501
1502C<I18N::Langinfo> has been upgraded from version 0.03 to 0.07.
1503
1504C<langinfo()> now defaults to using C<$_> if there is no argument given, just
5334145a 1505as the documentation has always claimed.
5076a392
FC
1506
1507=item *
1508
1509C<IO::Select> has been upgraded from version 1.17 to 1.18.
1510
1511It now allows IO::Handle objects (and objects in derived classes) to be
1512removed from an IO::Select set even if the underlying file descriptor is
1513closed or invalid.
1514
1515=item *
1516
d07561d3 1517C<IPC::Cmd> has been upgraded from version 0.54 to 0.70.
5076a392 1518
1984204c
FC
1519Resolves an issue with splitting Win32 command lines. An argument
1520consisting of the single character "0" used to be omitted (CPAN RT #62961).
5076a392
FC
1521
1522=item *
1523
1524C<IPC::Open3> has been upgraded from 1.05 to 1.08.
1525
4ed2cea4
FC
1526C<open3> now produces an error if the C<exec> call fails, allowing this
1527condition to be distinguished from a child process that exited with a
1528non-zero status [perl #72016].
1529
5076a392
FC
1530The internal C<xclose> routine now knows how to handle file descriptors, as
1531documented, so duplicating STDIN in a child process using its file
1532descriptor now works [perl #76474].
1533
1534=item *
1535
c8b41807
FR
1536C<IPC::SysV> has been upgraded from version 2.01 to 2.03.
1537
1538=item *
1539
ef79f038
FR
1540C<lib> has been upgraded from version 0.62 to 0.63.
1541
1542=item *
1543
5b1884f4 1544C<Locale::Maketext> has been upgraded from version 1.14 to 1.19.
5076a392 1545
1984204c 1546Locale::Maketext now supports external caches.
5076a392 1547
1984204c
FC
1548This upgrade also fixes an infinite loop in
1549C<Locale::Maketext::Guts::_compile()> when
5076a392
FC
1550working with tainted values (CPAN RT #40727).
1551
1984204c 1552C<< ->maketext >> calls will now back up and restore C<$@> so that error
5076a392
FC
1553messages are not suppressed (CPAN RT #34182).
1554
1555=item *
1556
3811bd2b
FR
1557C<Log::Message> has been upgraded from version 0.02 to 0.04.
1558
1559=item *
1560
8eb65377
FR
1561C<Log::Message::Simple> has been upgraded from version 0.06 to 0.08.
1562
1563=item *
1564
5076a392
FC
1565C<Math::BigInt> has been upgraded from version 1.89_01 to 1.994.
1566
1567This fixes, among other things, incorrect results when computing binomial
1568coefficients [perl #77640].
1569
1984204c 1570It also prevents C<sqrt($int)> from crashing under C<use bigrat;>
5076a392
FC
1571[perl #73534].
1572
1573=item *
1574
846c1cec
FR
1575C<Math::BigInt::FastCalc> has been upgraded from version 0.19 to 0.28.
1576
1577=item *
1578
fce4aef3
FR
1579C<Math::BigRat> has been upgraded from version 0.24 to 0.26_02.
1580
1581=item *
1582
12e26027
FR
1583C<Memoize> has been upgraded from version 1.01_03 to 1.02.
1584
1585=item *
1586
5076a392
FC
1587C<MIME::Base64> has been upgraded from 3.08 to 3.13.
1588
1589Includes new functions to calculate the length of encoded and decoded
1590base64 strings.
1591
1592Now provides C<encode_base64url> and C<decode_base64url> functions to process
1593the base64 scheme for "URL applications".
1594
1595=item *
1596
1597C<Module::Build> has been upgraded from version 0.3603 to 0.3800.
1598
1599A notable change is the deprecation of several modules.
1600Module::Build::Version has been deprecated and Module::Build now relies
1601directly upon L<version>. Module::Build::ModuleInfo has been deprecated in
1602favor of a standalone copy of it called L<Module::Metadata>.
1603Module::Build::YAML has been deprecated in favor of L<CPAN::Meta::YAML>.
1604
1605Module::Build now also generates META.json and MYMETA.json files
1606in accordance with version 2 of the CPAN distribution metadata specification,
1607L<CPAN::Meta::Spec>. The older format META.yml and MYMETA.yml files are
1608still generated, as well.
1609
1610=item *
1611
7259fe26 1612C<Module::CoreList> has been upgraded from version 2.29 to 2.47.
5076a392
FC
1613
1614Besides listing the updated core modules of this release, it also stops listing
1984204c 1615the C<Filespec> module. That module never existed in core. The scripts
5076a392 1616generating C<Module::CoreList> confused it with C<VMS::Filespec>, which actually
1984204c 1617is a core module as of perl 5.8.7.
5076a392
FC
1618
1619=item *
1620
193af05b
FR
1621C<Module::Load> has been upgraded from version 0.16 to 0.18.
1622
1623=item *
1624
5b3a054f
FR
1625C<Module::Load::Conditional> has been upgraded from version 0.34 to 0.44.
1626
1627=item *
1628
4f978a3b
FR
1629C<NDBM_File> has been upgraded from version 1.08 to 1.11.
1630
1631This fixes a memory leak when DBM filters are used.
1632
1633=item *
1634
d0aa5c91
FR
1635C<Net::Ping> has been upgraded from version 2.36 to 2.38.
1636
1637=item *
1638
d44b8a8c
FR
1639C<NEXT> has been upgraded from version 0.64 to 0.65.
1640
1641=item *
1642
678d4fd4
FR
1643C<Object::Accessor> has been upgraded from version 0.36 to 0.38.
1644
1645=item *
1646
34188656 1647C<ODBM_File> have been upgraded from version 1.07 to 1.10.
5076a392
FC
1648
1649This fixes a memory leak when DBM filters are used.
1650
1651=item *
1652
77be713d 1653C<overload> has been upgraded from 1.10 to 1.12.
5076a392
FC
1654
1655C<overload::Method> can now handle subroutines that are themselves blessed
1656into overloaded classes [perl #71998].
1657
5076a392
FC
1658The documentation has greatly improved. See L</Documentation> below.
1659
1660=item *
1661
f84c796e
FR
1662C<Params::Check> has been upgraded from version 0.26 to 0.28.
1663
1664=item *
1665
550ee92b
FR
1666C<parent> has been upgraded from version 0.223 to 0.225.
1667
1668=item *
1669
5076a392
FC
1670C<Parse::CPAN::Meta> has been upgraded from version 1.40 to 1.4401.
1671
1984204c 1672The latest Parse::CPAN::Meta can now read YAML and JSON files using
5076a392
FC
1673L<CPAN::Meta::YAML> and L<JSON::PP>, which are now part of the Perl core.
1674
1675=item *
1676
5076a392
FC
1677C<PerlIO::scalar> has been upgraded from 0.07 to 0.11.
1678
1679A C<read> after a C<seek> beyond the end of the string no longer thinks it
1680has data to read [perl #78716].
1681
1682=item *
1683
be3c8498
FR
1684C<Pod::LaTeX> has been upgraded from version 0.58 to 0.59.
1685
1686=item *
1687
fd8a2e89
FR
1688C<Pod::Perldoc> has been upgraded from version 3.15_02 to 3.15_03.
1689
1690=item *
1691
5bcb6583
FR
1692C<Pod::Simple> has been upgraded from version 3.13 to 3.16.
1693
1694=item *
1695
abb8c779 1696C<POSIX> has been upgraded from 1.19 to 1.24.
5076a392
FC
1697
1698It now includes constants for POSIX signal constants.
1699
1700=item *
1701
1984204c 1702C<re> has been upgraded from version 0.11 to 0.17.
5076a392
FC
1703
1704New C<use re "/flags"> pragma
1705
5076a392 1706The C<regmust> function used to crash when called on a regular expression
1984204c 1707belonging to a pluggable engine. Now it croaks instead.
5076a392
FC
1708
1709C<regmust> no longer leaks memory.
1710
1711=item *
1712
1713C<Safe> has been upgraded from version 2.25 to 2.29.
1714
cdc10f43
FC
1715Coderefs returned by C<reval()> and C<rdo()> are now wrapped via
1716C<wrap_code_refs> (5.12.1).
1717
5076a392
FC
1718This fixes a possible infinite loop when looking for coderefs.
1719
cdc10f43 1720It adds several version::vxs::* routines to the default share.
5076a392
FC
1721
1722=item *
1723
5076a392
FC
1724C<SelfLoader> has been upgraded from 1.17 to 1.18.
1725
1726It now works in taint mode [perl #72062].
1727
1728=item *
1729
1730C<sigtrap> has been upgraded from version 1.04 to 1.05.
1731
1732It no longer tries to modify read-only arguments when generating a
1733backtrace [perl #72340].
1734
1735=item *
1736
1984204c 1737C<Socket> has been upgraded from version 1.87 to 1.94.
5076a392 1738
1984204c 1739See L</IPv6 support>, above.
5076a392
FC
1740
1741=item *
1742
1743C<Storable> has been upgraded from version 2.22 to 2.27.
1744
1745Includes performance improvement for overloaded classes.
1746
5076a392 1747This adds support for serialising code references that contain UTF-8 strings
1984204c
FC
1748correctly. The Storable minor version
1749number changed as a result, meaning that
5076a392
FC
1750Storable users who set C<$Storable::accept_future_minor> to a C<FALSE> value
1751will see errors (see L<Storable/FORWARD COMPATIBILITY> for more details).
1752
1753Freezing no longer gets confused if the Perl stack gets reallocated
1754during freezing [perl #80074].
1755
1756=item *
1757
90c6e78f
FR
1758C<Term::ANSIColor> has been upgraded from version 2.02 to 3.00.
1759
1760=item *
1761
d9f2f059
FR
1762C<Term::UI> has been upgraded from version 0.20 to 0.26.
1763
1764=item *
1765
80ebb519
FR
1766C<Test::Harness> has been upgraded from version 3.17 to 3.23.
1767
1768=item *
1769
5076a392
FC
1770C<Test::Simple> has been upgraded from version 0.94 to 0.98.
1771
1772Among many other things, subtests without a C<plan> or C<no_plan> now have an
1773implicit C<done_testing()> added to them.
1774
1775=item *
1776
5076a392
FC
1777C<Thread::Semaphore> has been upgraded from version 2.09 to 2.12.
1778
1984204c
FC
1779It provides two new methods that give more control over the decrementing of
1780semaphores: C<down_nb> and C<down_force>.
5076a392
FC
1781
1782=item *
1783
f0d895e1
FR
1784C<Thread::Queue> has been upgraded from version 2.11 to 2.12.
1785
1786=item *
1787
1a6b954e
FR
1788C<threads> has been upgraded from version 1.75 to 1.83.
1789
1790=item *
1791
55816daa
FR
1792C<threads::shared> has been upgraded from version 1.32 to 1.36.
1793
1794=item *
1795
5076a392
FC
1796C<Tie::Hash> has been upgraded from version 1.03 to 1.04.
1797
1798Calling C<< Tie::Hash-E<gt>TIEHASH() >> used to loop forever. Now it C<croak>s.
1799
1800=item *
1801
ed68b07e
FR
1802C<Tie::RefHash> has been upgraded from version 1.38 to 1.39.
1803
1804=item *
1805
bb3c221a
FR
1806C<Time::HiRes> has been upgraded from version 1.9719 to 1.9721_01.
1807
1808=item *
1809
97fa568b
FR
1810C<Time::Local> has been upgraded from version 1.1901_01 to 1.2000.
1811
1812=item *
1813
a83cb732
FR
1814C<Time::Piece> has been upgraded from version 1.15_01 to 1.20_01.
1815
1816=item *
1817
5076a392
FC
1818C<Unicode::Collate> has been upgraded from version 0.52_01 to 0.73.
1819
1984204c 1820Unicode::Collate has been updated to use Unicode 6.0.0.
5076a392 1821
1984204c
FC
1822Unicode::Collate::Locale now supports a plethora of new locales: ar, be,
1823bg, de__phonebook, hu, hy, kk, mk, nso, om, tn, vi, hr, ig, ja, ko, ru, sq,
1824se, sr, to, uk, zh, zh__big5han, zh__gb2312han, zh__pinyin and zh__stroke.
5076a392
FC
1825
1826The following modules have been added:
1827
1828C<Unicode::Collate::CJK::Big5> for C<zh__big5han> which makes
1829tailoring of CJK Unified Ideographs in the order of CLDR's big5han ordering.
1830
1831C<Unicode::Collate::CJK::GB2312> for C<zh__gb2312han> which makes
1832tailoring of CJK Unified Ideographs in the order of CLDR's gb2312han ordering.
1833
1834C<Unicode::Collate::CJK::JISX0208> which makes tailoring of 6355 kanji
1835(CJK Unified Ideographs) in the JIS X 0208 order.
1836
1837C<Unicode::Collate::CJK::Korean> which makes tailoring of CJK Unified Ideographs
1838in the order of CLDR's Korean ordering.
1839
1840C<Unicode::Collate::CJK::Pinyin> for C<zh__pinyin> which makes
1841tailoring of CJK Unified Ideographs in the order of CLDR's pinyin ordering.
1842
1843C<Unicode::Collate::CJK::Stroke> for C<zh__stroke> which makes
1844tailoring of CJK Unified Ideographs in the order of CLDR's stroke ordering.
1845
5076a392
FC
1846This also sees the switch from using the pure-perl version of this
1847module to the XS version.
1848
1849=item *
1850
ec52b54b
FR
1851C<Unicode::Normalize> has been upgraded from version 1.03 to 1.10.
1852
1853=item *
1854
5076a392
FC
1855C<Unicode::UCD> has been upgraded from version 0.27 to 0.32.
1856
1984204c
FC
1857A new function, C<Unicode::UCD::num()>, has been added. This function
1858returns the numeric value of the string passed it or C<undef> if the string
1859in its entirety has no "safe" numeric value. (For more detail, and for the
1860definition of "safe", see L<Unicode::UCD/num>.)
5076a392 1861
1984204c 1862This upgrade also includes a number of bug fixes:
5076a392
FC
1863
1864=over 4
1865
1866=item charinfo()
1867
1868=over 4
1869
1870=item *
1871
1872It is now updated to Unicode Version 6 with Corrigendum #8, except,
1873as with Perl 5.14, the code point at U+1F514 has no name.
1874
1875=item *
1876
1877The Hangul syllable code points have the correct names, and their
1878decompositions are always output without requiring L<Lingua::KO::Hangul::Util>
1879to be installed.
1880
1881=item *
1882
54c7bb16
FC
1883The CJK (Chinese-Japanese-Korean) code points U+2A700 to U+2B734
1884and U+2B740 to U+2B81D are now properly handled.
5076a392
FC
1885
1886=item *
1887
1888The numeric values are now output for those CJK code points that have them.
1889
1890=item *
1891
1892The names that are output for code points with multiple aliases are now the
1893corrected ones.
1894
1895=back
1896
1897=item charscript()
1898
1899This now correctly returns "Unknown" instead of C<undef> for the script
1900of a code point that hasn't been assigned another one.
1901
1902=item charblock()
1903
1904This now correctly returns "No_Block" instead of C<undef> for the block
1905of a code point that hasn't been assigned to another one.
1906
1907=back
1908
5076a392
FC
1909=item *
1910
1911C<version> has been upgraded from 0.82 to 0.88.
1912
1984204c 1913Due to a bug, now fixed, the C<is_strict> and C<is_lax> functions did not
cdc10f43 1914work when exported (5.12.1).
5076a392
FC
1915
1916=item *
1917
3e625598 1918C<warnings> has been upgraded from version 1.09 to 1.12.
5076a392
FC
1919
1920Calling C<use warnings> without arguments is now significantly more efficient.
1921
4f978a3b
FR
1922=item *
1923
1924C<warnings::register> have been upgraded from version 1.01 to 1.02.
1925
5076a392
FC
1926It is now possible to register warning categories other than the names of
1927packages using C<warnings::register>. See L<perllexwarn> for more information.
1928
1929=item *
1930
62e270c2
FR
1931C<XSLoader> has been upgraded from version 0.10 to 0.13.
1932
1933=item *
1934
5076a392
FC
1935C<VMS::DCLsym> has been upgraded from version 1.03 to 1.05.
1936
1937Two bugs have been fixed [perl #84086]:
1938
1939The symbol table name was lost when tying a hash, due to a thinko in
1940C<TIEHASH>. The result was that all tied hashes interacted with the
1941local symbol table.
1942
1943Unless a symbol table name had been explicitly specified in the call
1944to the constructor, querying the special key ':LOCAL' failed to
1945identify objects connected to the local symbol table.
1946
1947=item *
1948
1949C<Win32> has been upgraded from version 0.39 to 0.44.
1950
1984204c
FC
1951This release has several new functions: C<Win32::GetSystemMetrics>,
1952C<Win32::GetProductInfo>, C<Win32::GetOSDisplayName>.
5076a392 1953
1984204c
FC
1954The names returned by C<Win32::GetOSName> and C<Win32::GetOSDisplayName>
1955have been corrected.
5076a392 1956
5076a392
FC
1957=back
1958
5076a392
FC
1959=head2 Removed Modules and Pragmata
1960
1961The following modules have been removed from the core distribution, and if
1962needed should be installed from CPAN instead.
1963
1964=over
1965
4f978a3b
FR
1966=item *
1967
1968C<Class::ISA> has been removed from the Perl core. Prior version was 0.36.
5076a392 1969
4f978a3b
FR
1970=item *
1971
1972C<Pod::Plainer> has been removed from the Perl core. Prior version was 1.02.
1973
1974=item *
5076a392 1975
4f978a3b 1976C<Switch> has been removed from the Perl core. Prior version was 2.16.
5076a392
FC
1977
1978=back
1979
1980The removal of C<Shell> has been deferred until after 5.14, as the
1981implementation of C<Shell> shipped with 5.12.0 did not correctly issue the
1982warning that it was to be removed from core.
1983
1984=head1 Documentation
1985
5076a392
FC
1986=head2 New Documentation
1987
41e29def 1988=head3 L<perlgpl>
5076a392
FC
1989
1990L<perlgpl> has been updated to contain GPL version 1, as is included in the
cdc10f43 1991F<README> distributed with perl (5.12.1).
5076a392 1992
41e29def 1993=head3 Perl 5.12.x delta files
5076a392 1994
41e29def
FC
1995The perldelta files for Perl 5.12.1 to 5.12.3 have been added from the
1996maintenance branch: L<perl5121delta>, L<perl5122delta>, L<perl5123delta>.
5076a392
FC
1997
1998=head3 L<perlpodstyle>
1999
2000New style guide for POD documentation,
2001split mostly from the NOTES section of the pod2man man page.
2002
41e29def
FC
2003=head3 L<perlsource>, L<perlinterp>, L<perlhacktut>, and L<perlhacktips>
2004
2005See L</L<perlhack> and perlrepository revamp>, below.
5076a392
FC
2006
2007=head2 Changes to Existing Documentation
2008
41e29def 2009=head3 L<perlmodlib> is now complete
4ed2cea4
FC
2010
2011The perlmodlib page that came with Perl 5.12.0 was missing a lot of
2012modules, due to a bug in the script that generates the list. This has been
cdc10f43 2013fixed [perl #74332] (5.12.1).
4ed2cea4 2014
41e29def 2015=head3 Replace wrong tr/// table in L<perlebcdic>
5076a392 2016
41e29def 2017L<perlebcdic> contains a helpful table to use in tr/// to convert
5076a392
FC
2018between EBCDIC and Latin1/ASCII. Unfortunately, the table was the
2019inverse of the one it describes, though the code that used the table
2020worked correctly for the specific example given.
2021
2022The table has been changed to its inverse, and the sample code changed
2023to correspond, as this is easier for the person trying to follow the
2024instructions since deriving the old table is somewhat more complicated.
2025
2026The table has also been changed to hex from octal, as that is more the norm
2027these days, and the recipes in the pod altered to print out leading
41e29def 2028zeros to make all the values the same length.
5076a392 2029
41e29def 2030=head3 Tricks for user-defined casing
5076a392 2031
41e29def
FC
2032L<perlunicode> now contains an explanation of how to override, mangle
2033and otherwise tweak the way perl handles upper-, lower- and other-case
2034conversions on Unicode data, and how to provide scoped changes to alter
2035one's own code's behaviour without stomping on anybody else.
5076a392
FC
2036
2037=head3 INSTALL explicitly states the requirement for C89
2038
d430b8e7
FC
2039This was already true but it's now Officially Stated For The Record
2040(5.12.2).
5076a392 2041
41e29def 2042=head3 Explanation of C<\xI<HH>> and C<\oI<OOO>> escapes
5076a392 2043
41e29def
FC
2044L<perlop> has been updated with more detailed explanation of these two
2045character escapes.
5076a392 2046
41e29def 2047=head3 C<-0I<NNN>> switch
5076a392 2048
41e29def 2049In L<perlrun>, the behavior of the C<-0NNN> switch for C<-0400> or higher
d430b8e7 2050has been clarified (5.12.2).
5076a392 2051
cdc10f43
FC
2052=head3 Maintenance policy
2053
2054L<perlpolicy> now contains the policy on what patches are acceptable for
2055maintenance branches (5.12.1).
2056
41e29def 2057=head3 Deprecation policy
5076a392 2058
41e29def 2059L<perlpolicy> now contains the policy on compatibility and deprecation
d430b8e7 2060along with definitions of terms like "deprecation" (5.12.2).
5076a392 2061
41e29def 2062=head3 New descriptions in L<perldiag>
5076a392
FC
2063
2064The following existing diagnostics are now documented:
2065
2066=over 4
2067
2068=item *
2069
2070L<Ambiguous use of %c resolved as operator %c|perldiag/"Ambiguous use of %c resolved as operator %c">
2071
2072=item *
2073
2074L<Ambiguous use of %c{%s} resolved to %c%s|perldiag/"Ambiguous use of %c{%s} resolved to %c%s">
2075
2076=item *
2077
2078L<Ambiguous use of %c{%s%s} resolved to %c%s%s|perldiag/"Ambiguous use of %c{%s%s} resolved to %c%s%s">
2079
2080=item *
2081
2082L<Ambiguous use of -%s resolved as -&%s()|perldiag/"Ambiguous use of -%s resolved as -&%s()">
2083
2084=item *
2085
2086L<Invalid strict version format (%s)|perldiag/"Invalid strict version format (%s)">
2087
2088=item *
2089
2090L<Invalid version format (%s)|perldiag/"Invalid version format (%s)">
2091
2092=item *
2093
2094L<Invalid version object|perldiag/"Invalid version object">
2095
2096=back
2097
5076a392
FC
2098=head3 L<perlbook>
2099
41e29def 2100L<perlbook> has been expanded to cover many more popular books.
5076a392 2101
41e29def 2102=head3 C<SvTRUE> macro
5076a392 2103
41e29def
FC
2104The documentation for the C<SvTRUE> macro in
2105L<perlapi> was simply wrong in stating that
5076a392
FC
2106get-magic is not processed. It has been corrected.
2107
41e29def 2108=head3 L<perlvar> revamp
5076a392 2109
41e29def 2110L<perlvar> reorders the variables and groups them by topic. Each variable
5076a392 2111introduced after Perl 5.000 notes the first version in which it is
41e29def 2112available. L<perlvar> also has a new section for deprecated variables to
5076a392
FC
2113note when they were removed.
2114
41e29def 2115=head3 Array and hash slices in scalar context
5076a392 2116
41e29def 2117These are now documented in L<perldata>.
5076a392 2118
41e29def 2119=head3 C<use locale> and formats
5076a392
FC
2120
2121L<perlform> and L<perllocale> have been corrected to state that
2122C<use locale> affects formats.
2123
5076a392
FC
2124=head3 L<overload>
2125
5076a392
FC
2126L<overload>'s documentation has practically undergone a rewrite. It
2127is now much more straightforward and clear.
2128
41e29def 2129=head3 L<perlhack> and perlrepository revamp
5076a392
FC
2130
2131The L<perlhack> and perlrepository documents have been heavily edited and
2132split up into several new documents.
2133
2134The L<perlhack> document is now much shorter, and focuses on the Perl 5
2135development process and submitting patches to Perl. The technical content has
2136been moved to several new documents, L<perlsource>, L<perlinterp>,
2137L<perlhacktut>, and L<perlhacktips>. This technical content has only been
2138lightly edited.
2139
2140The perlrepository document has been renamed to L<perlgit>. This new document
2141is just a how-to on using git with the Perl source code. Any other content
2142that used to be in perlrepository has been moved to perlhack.
2143
41e29def 2144=head3 Time::Piece examples
5076a392
FC
2145
2146Examples in L<perlfaq4> have been updated to show the use of
41e29def 2147L<Time::Piece>.
5076a392
FC
2148
2149=head1 Diagnostics
2150
2151The following additions or changes have been made to diagnostic output,
2152including warnings and fatal error messages. For the complete list of
2153diagnostic messages, see L<perldiag>.
2154
2155=head2 New Diagnostics
2156
a593b319
FC
2157=head3 New Errors
2158
5076a392
FC
2159=over
2160
a593b319 2161=item Closure prototype called
5076a392 2162
a593b319
FC
2163This error occurs when a subroutine reference passed to an attribute
2164handler is called, if the subroutine is a closure [perl #68560].
5076a392 2165
a593b319 2166=item Insecure user-defined property %s
5076a392 2167
a593b319
FC
2168Perl detected tainted data when trying to compile a regular
2169expression that contains a call to a user-defined character property
2170function, i.e. C<\p{IsFoo}> or C<\p{InFoo}>.
2171See L<perlunicode/User-Defined Character Properties> and L<perlsec>.
5076a392 2172
a593b319 2173=item panic: gp_free failed to free glob pointer - something is repeatedly re-creating entries
5076a392 2174
a593b319
FC
2175This new error is triggered if a destructor called on an object in a
2176typeglob that is being freed creates a new typeglob entry containing an
2177object with a destructor that creates a new entry containing an object....
5076a392 2178
a593b319 2179=item Parsing code internal error (%s)
5076a392 2180
a593b319
FC
2181This new fatal error is produced when parsing
2182code supplied by an extension violates the
2183parser's API in a detectable way.
5076a392 2184
a593b319 2185=item refcnt: fd %d%s
5076a392 2186
a593b319
FC
2187This new error only occurs if a internal consistency check fails when a
2188pipe is about to be closed.
5076a392 2189
a593b319 2190=item Regexp modifier "/%c" may not appear twice
5076a392 2191
a593b319
FC
2192The regular expression pattern has one of the
2193mutually exclusive modifiers repeated.
5076a392 2194
a593b319 2195=item Regexp modifiers "/%c" and "/%c" are mutually exclusive
5076a392 2196
a593b319
FC
2197The regular expression pattern has more than one of the mutually
2198exclusive modifiers.
5076a392 2199
a593b319 2200=item Using !~ with %s doesn't make sense
5076a392 2201
a593b319 2202This error occurs when C<!~> is used with C<s///r> or C<y///r>.
5076a392 2203
a593b319 2204=back
5076a392 2205
a593b319 2206=head3 New Warnings
5076a392 2207
a593b319 2208=over
5076a392 2209
a593b319 2210=item "\b{" is deprecated; use "\b\{" instead
5076a392 2211
a593b319 2212=item "\B{" is deprecated; use "\B\{" instead
5076a392 2213
a593b319
FC
2214Use of an unescaped "{" immediately following a C<\b> or C<\B> is now
2215deprecated so as to reserve its use for Perl itself in a future release.
5076a392 2216
a593b319 2217=item Operation "%s" returns its argument for ...
5076a392 2218
a593b319
FC
2219Performing an operation requiring Unicode semantics (such as case-folding)
2220on a Unicode surrogate or a non-Unicode character now triggers a warning:
2221'Operation "%s" returns its argument for ...'.
5076a392 2222
a593b319
FC
2223=item Use of qw(...) as parentheses is deprecated
2224
2225See L</"Use of qw(...) as parentheses">, above, for details.
5076a392
FC
2226
2227=back
2228
2229=head2 Changes to Existing Diagnostics
2230
2231=over 4
2232
2233=item *
2234
4ed2cea4
FC
2235The "Variable $foo is not imported" warning that precedes a
2236C<strict 'vars'> error has now been assigned the "misc" category, so that
2237C<no warnings> will suppress it [perl #73712].
2238
2239=item *
2240
5076a392
FC
2241C<warn> and C<die> now produce 'Wide character' warnings when fed a
2242character outside the byte range if STDERR is a byte-sized handle.
2243
2244=item *
2245
2246The 'Layer does not match this perl' error message has been replaced with
a593b319 2247these more helpful messages [perl #73754]:
5076a392
FC
2248
2249=over 4
2250
2251=item *
2252
2253PerlIO layer function table size (%d) does not match size expected by this
2254perl (%d)
2255
2256=item *
2257
2258PerlIO layer instance size (%d) does not match size expected by this perl
2259(%d)
2260
2261=back
2262
5076a392
FC
2263=item *
2264
2265The "Found = in conditional" warning that is emitted when a constant is
2266assigned to a variable in a condition is now withheld if the constant is
2267actually a subroutine or one generated by C<use constant>, since the value
2268of the constant may not be known at the time the program is written
2269[perl #77762].
2270
2271=item *
2272
2273Previously, if none of the C<gethostbyaddr>, C<gethostbyname> and
2274C<gethostent> functions were implemented on a given platform, they would
2275all die with the message 'Unsupported socket function "gethostent" called',
2276with analogous messages for C<getnet*> and C<getserv*>. This has been
2277corrected.
2278
2279=item *
2280
a593b319
FC
2281The warning message about unrecognized regular expression escapes passed
2282through has been changed to include any literal '{' following the
2283two-character escape. E.g., "\q{" is now emitted instead of "\q".
5076a392
FC
2284
2285=back
2286
2287=head1 Utility Changes
2288
0b88cc74 2289=head3 L<perlbug>
5076a392
FC
2290
2291=over 4
2292
2293=item *
2294
0b88cc74
FC
2295L<perlbug> now looks in the EMAIL environment variable for a return address
2296if the REPLY-TO and REPLYTO variables are empty.
5076a392
FC
2297
2298=item *
2299
0b88cc74
FC
2300L<perlbug> did not previously generate a From: header, potentially
2301resulting in dropped mail. Now it does include that header.
5076a392
FC
2302
2303=item *
2304
0b88cc74 2305The user's address is now used as the return-path.
4ed2cea4 2306
0b88cc74
FC
2307Many systems these days don't have a valid Internet domain name and
2308perlbug@perl.org does not accept email with a return-path that does
2309not resolve. So the user's address is now passed to sendmail so it's
2310less likely to get stuck in a mail queue somewhere [perl #82996].
5076a392 2311
2c389f6c
FC
2312=item *
2313
d430b8e7
FC
2314L<perlbug> now always gives the reporter a chance to change the email
2315address it guesses for them (5.12.2).
2316
2317=item *
2318
2319L<perlbug> should no longer warn about uninitialized values when using the C<-d>
2320and C<-v> options (5.12.2).
2c389f6c 2321
5076a392
FC
2322=back
2323
0b88cc74 2324=head3 L<perl5db.pl>
5076a392 2325
0b88cc74 2326=over
5076a392
FC
2327
2328=item *
2329
0b88cc74
FC
2330The remote terminal works after forking and spawns new sessions - one
2331for each forked process.
5076a392
FC
2332
2333=back
2334
0b88cc74 2335=head3 L<ptargrep>
5076a392
FC
2336
2337=over 4
2338
2339=item *
2340
0b88cc74
FC
2341L<ptargrep> is a new utility to apply pattern matching to the contents of
2342files in a tar archive. It comes with C<Archive::Tar>.
5076a392
FC
2343
2344=back
2345
2346=head1 Configuration and Compilation
2347
61752d82
FC
2348See also L</"Naming fixes in Policy_sh.SH may invalidate Policy.sh">,
2349above.
2350
5076a392
FC
2351=over 4
2352
2353=item *
2354
87595b22
FC
2355CCINCDIR and CCLIBDIR for the mingw64
2356cross-compiler are now correctly under
5076a392
FC
2357$(CCHOME)\mingw\include and \lib rather than immediately below $(CCHOME).
2358
5076a392
FC
2359This means the 'incpath', 'libpth', 'ldflags', 'lddlflags' and
2360'ldflags_nolargefiles' values in Config.pm and Config_heavy.pl are now
87595b22 2361set correctly.
5076a392
FC
2362
2363=item *
2364
87595b22
FC
2365'make test.valgrind' has been adjusted to account for cpan/dist/ext
2366separation.
5076a392
FC
2367
2368=item *
2369
2370On compilers that support it, C<-Wwrite-strings> is now added to cflags by
2371default.
2372
2373=item *
2374
2375The C<Encode> module can now (once again) be included in a static Perl
2376build. The special-case handling for this situation got broken in Perl
23775.11.0, and has now been repaired.
2378
1e463951
FC
2379=item *
2380
2381The previous default size of a PerlIO buffer (4096 bytes) has been increased
2382to the larger of 8192 bytes and your local BUFSIZ. Benchmarks show that doubling
2383this decade-old default increases read and write performance in the neighborhood
2384of 25% to 50% when using the default layers of perlio on top of unix. To choose
2385a non-default size, such as to get back the old value or to obtain an even
2386larger value, configure with:
2387
2388 ./Configure -Accflags=-DPERLIOBUF_DEFAULT_BUFSIZ=N
2389
2390where N is the desired size in bytes; it should probably be a multiple of
2391your page size.
2392
d430b8e7
FC
2393=item *
2394
2395An "incompatible operand types" error in ternary expressions when building
2396with C<clang> has been fixed (5.12.2).
2397
2398=item *
2399
2400Perl now skips setuid C<File::Copy> tests on partitions it detects to be mounted
2401as C<nosuid> (5.12.2).
2402
5076a392
FC
2403=back
2404
5076a392
FC
2405=head1 Platform Support
2406
5076a392
FC
2407=head2 New Platforms
2408
5076a392
FC
2409=over 4
2410
2411=item AIX
2412
cdc10f43 2413Perl now builds on AIX 4.2 (5.12.1).
5076a392
FC
2414
2415=back
2416
2417=head2 Discontinued Platforms
2418
2419=over 4
2420
5076a392
FC
2421=item Apollo DomainOS
2422
2423The last vestiges of support for this platform have been excised from the
2424Perl distribution. It was officially discontinued in version 5.12.0. It had
2425not worked for years before that.
2426
2427=item MacOS Classic
2428
2429The last vestiges of support for this platform have been excised from the
2430Perl distribution. It was officially discontinued in an earlier version.
2431
2432=back
2433
2434=head2 Platform-Specific Notes
2435
d430b8e7
FC
2436=head3 AIX
2437
2438=over
2439
2440=item *
2441
2442F<README.aix> has been updated with information about the XL C/C++ V11 compiler
2443suite (5.12.2).
2444
2445=back
2446
2447=head3 ARM
2448
2449=over
2450
2451=item *
2452
2453The C<d_u32align> configuration probe on ARM has been fixed (5.12.2).
2454
2455=back
2456
554003a2 2457=head3 Cygwin
5076a392
FC
2458
2459=over 4
2460
2461=item *
2462
554003a2 2463MakeMaker has been updated to build man pages on cygwin.
5076a392
FC
2464
2465=item *
2466
554003a2
FC
2467Improved rebase behaviour
2468
2469If a dll is updated on cygwin the old imagebase address is reused.
2470This solves most rebase errors, especially when updating on core dll's.
2471See L<http://www.tishler.net/jason/software/rebase/rebase-2.4.2.README> for more information.
5076a392
FC
2472
2473=item *
2474
554003a2 2475Support for the standard cygwin dll prefix, which is e.g. needed for FFI's
5076a392
FC
2476
2477=item *
2478
554003a2 2479Updated build hints file
5076a392
FC
2480
2481=back
2482
cdc10f43
FC
2483=head3 FreeBSD 7
2484
2485=over
2486
2487=item *
2488
2489FreeBSD 7 no longer contains F</usr/bin/objformat>. At build time,
2490Perl now skips the F<objformat> check for versions 7 and higher and
2491assumes ELF (5.12.1).
2492
2493=back
2494
2495=head3 HP-UX
2496
2497=over
2498
2499=item *
2500
2501Perl now allows -Duse64bitint without promoting to use64bitall on HP-UX
2502(5.12.1).
2503
2504=back
2505
554003a2 2506=head3 IRIX
5076a392
FC
2507
2508Conversion of strings to floating-point numbers is now more accurate on
2509IRIX systems [perl #32380].
2510
554003a2 2511=head3 Mac OS X
5076a392
FC
2512
2513Early versions of Mac OS X (Darwin) had buggy implementations of the
2514C<setregid>, C<setreuid>, C<setrgid> and C<setruid> functions, so perl
2515would pretend they did not exist.
2516
2517These functions are now recognised on Mac OS 10.5 (Leopard; Darwin 9) and
2518higher, as they have been fixed [perl #72990].
2519
554003a2 2520=head3 MirBSD
5076a392 2521
554003a2
FC
2522Previously if you built perl with a shared libperl.so on MirBSD (the
2523default config), it would work up to the installation; however, once
2524installed, it would be unable to find libperl. So path handling is now
2525treated as in the other BSD dialects.
5076a392 2526
554003a2 2527=head3 NetBSD
5076a392 2528
554003a2
FC
2529The NetBSD hints file has been changed to make the system's malloc the
2530default.
5076a392 2531
554003a2 2532=head3 Recent OpenBSDs now use perl's malloc
5076a392 2533
554003a2
FC
2534OpenBSD E<gt> 3.7 has a new malloc implementation which is mmap-based
2535and as such can release memory back to the OS; however, perl's use of
2536this malloc causes a substantial slowdown so we now default to using
2537perl's malloc instead [perl #75742].
5076a392 2538
554003a2 2539=head3 OpenVOS
5076a392 2540
554003a2 2541perl now builds again with OpenVOS (formerly known as Stratus VOS)
5a553547 2542[perl #78132] (5.12.3).
5076a392 2543
554003a2 2544=head3 Solaris
5076a392 2545
554003a2 2546DTrace is now supported on Solaris. There used to be build failures, but
5a553547 2547these have been fixed [perl #73630] (5.12.3).
5076a392 2548
554003a2 2549=head3 VMS
5076a392
FC
2550
2551=over
2552
2553=item *
2554
cdc10f43
FC
2555It's now possible to build extensions on older (pre 7.3-2) VMS systems.
2556
2557DCL symbol length was limited to 1K up until about seven years or
2558so ago, but there was no particularly deep reason to prevent those
2559older systems from configuring and building Perl (5.12.1).
2560
2561=item *
2562
2563We fixed the previously-broken C<-Uuseperlio> build on VMS.
2564
2565We were checking a variable that doesn't exist in the non-default
2566case of disabling perlio. Now we only look at it when it exists (5.12.1).
2567
2568=item *
2569
2570We fixed the -Uuseperlio command-line option in configure.com.
2571
2572Formerly it only worked if you went through all the questions
2573interactively and explicitly answered no (5.12.1).
2574
2575=item *
2576
554003a2 2577C<PerlIOUnix_open> now honours the default permissions on VMS.
5076a392 2578
554003a2
FC
2579When C<perlio> became the default and C<unixio> became the default bottom layer,
2580the most common path for creating files from Perl became C<PerlIOUnix_open>,
2581which has always explicitly used C<0666> as the permission mask.
5076a392 2582
554003a2
FC
2583To avoid this, C<0777> is now passed as the permissions to C<open()>. In the
2584VMS CRTL, C<0777> has a special meaning over and above intersecting with the
2585current umask; specifically, it allows Unix syscalls to preserve native default
5a553547
FC
2586permissions (5.12.3).
2587
2588=item *
2589
2590Spurious record boundaries are no longer
2591introduced by the PerlIO layer during output (5.12.3).
5076a392
FC
2592
2593=item *
2594
554003a2
FC
2595The shortening of symbols longer than 31 characters in the C sources is
2596now done by the compiler rather than by xsubpp (which could only do so
2597for generated symbols in XS code).
5076a392
FC
2598
2599=item *
2600
554003a2
FC
2601Record-oriented files (record format variable or variable with fixed control)
2602opened for write by the perlio layer will now be line-buffered to prevent the
2603introduction of spurious line breaks whenever the perlio buffer fills up.
5076a392 2604
d430b8e7
FC
2605=item *
2606
2607F<git_version.h> is now installed on VMS. This was an oversight in v5.12.0 which
2608caused some extensions to fail to build (5.12.2).
2609
2610=item *
2611
2612Several memory leaks in L<stat()|perlfunc/"stat FILEHANDLE"> have been fixed (5.12.2).
2613
2614=item *
2615
2616A memory leak in C<Perl_rename()> due to a double allocation has been
2617fixed (5.12.2).
2618
2619=item *
2620
2621A memory leak in C<vms_fid_to_name()> (used by C<realpath()> and
2622C<realname()>) has been fixed (5.12.2).
2623
5076a392
FC
2624=back
2625
554003a2 2626=head3 Windows
5076a392 2627
5a1f7719
FC
2628See also L</"fork() emulation will not wait for signalled children"> and
2629L</"Perl source code is read in text mode on Windows">, above.
2630
5076a392
FC
2631=over 4
2632
2633=item *
2634
554003a2 2635Fixed build process for SDK2003SP1 compilers.
5076a392 2636
554003a2 2637=item *
5076a392 2638
01b1a9e4
FC
2639Compilation with Visual Studio 2010 is now supported.
2640
2641=item *
2642
554003a2
FC
2643When using old 32-bit compilers, the define C<_USE_32BIT_TIME_T> will now
2644be set in C<$Config{ccflags}>. This improves portability when compiling
2645XS extensions using new compilers, but for a perl compiled with old 32-bit
2646compilers.
5076a392
FC
2647
2648=item *
2649
554003a2
FC
2650C<$Config{gccversion}> is now set correctly when perl is built using the
2651mingw64 compiler from L<http://mingw64.org> [perl #73754].
5076a392 2652
554003a2
FC
2653=item *
2654
d430b8e7
FC
2655When building Perl with the mingw64 x64 cross-compiler C<incpath>,
2656C<libpth>, C<ldflags>, C<lddlflags> and C<ldflags_nolargefiles> values
2657in F<Config.pm> and F<Config_heavy.pl> were not previously being set
2658correctly because, with that compiler, the include and lib directories
2659are not immediately below C<$(CCHOME)> (5.12.2).
2660
2661=item *
2662
554003a2
FC
2663The build process proceeds more smoothly with mingw and dmake when
2664F<C:\MSYS\bin> is in the PATH, due to a C<Cwd> fix.
5076a392
FC
2665
2666=item *
2667
554003a2
FC
2668Support for building with Visual C++ 2010 is now underway, but is not yet
2669complete. See F<README.win32> or L<perlwin32> for more details.
5076a392 2670
554003a2
FC
2671=item *
2672
2673The option to use an externally-supplied C<crypt()>, or to build with no
2674C<crypt()> at all, has been removed. Perl supplies its own C<crypt()>
2675implementation for Windows, and the political situation that required
2676this part of the distribution to sometimes be omitted is long gone.
5076a392
FC
2677
2678=back
2679
2680=head1 Internal Changes
2681
1e463951 2682=head2 New APIs
5076a392 2683
1e463951 2684=head3 CLONE_PARAMS structure added to ease correct thread creation
5076a392 2685
1e463951
FC
2686Modules that create threads should now create C<CLONE_PARAMS> structures
2687by calling the new function C<Perl_clone_params_new()>, and free them with
2688C<Perl_clone_params_del()>. This will ensure compatibility with any future
2689changes to the internals of the C<CLONE_PARAMS> structure layout, and that
2690it is correctly allocated and initialised.
5076a392 2691
1e463951 2692=head3 New parsing functions
5076a392 2693
1e463951
FC
2694Several functions have been added for parsing statements or multiple
2695statements:
5076a392 2696
1e463951 2697=over
5076a392
FC
2698
2699=item *
2700
1e463951 2701C<parse_fullstmt> parses a complete Perl statement.
5076a392
FC
2702
2703=item *
2704
1e463951
FC
2705C<parse_stmtseq> parses a sequence of statements, up
2706to closing brace or EOF.
5076a392
FC
2707
2708=item *
2709
1e463951 2710C<parse_block> parses a block [perl #78222].
5076a392
FC
2711
2712=item *
2713
1e463951
FC
2714C<parse_barestmt> parses a statement
2715without a label.
5076a392
FC
2716
2717=item *
2718
1e463951 2719C<parse_label> parses a statement label, separate from statements.
5076a392 2720
1e463951 2721=back
5076a392 2722
1e463951
FC
2723The
2724L<C<parse_fullexpr()>|perlapi/parse_fullexpr>,
2725L<C<parse_listexpr()>|perlapi/parse_listexpr>,
2726L<C<parse_termexpr()>|perlapi/parse_termexpr>, and
2727L<C<parse_arithexpr()>|perlapi/parse_arithexpr>
2728functions have been added to the API. They perform
2729recursive-descent parsing of expressions at various precedence levels.
2730They are expected to be used by syntax plugins.
5076a392 2731
1e463951 2732See L<perlapi> for details.
5076a392 2733
1e463951 2734=head3 Hints hash API
5076a392 2735
1e463951
FC
2736A new C API for introspecting the hinthash C<%^H> at runtime has been
2737added. See C<cop_hints_2hv>, C<cop_hints_fetchpvn>, C<cop_hints_fetchpvs>,
2738C<cop_hints_fetchsv>, and C<hv_copy_hints_hv> in L<perlapi> for details.
5076a392 2739
1e463951
FC
2740A new, experimental API has been added for accessing the internal
2741structure that Perl uses for C<%^H>. See the functions beginning with
2742C<cophh_> in L<perlapi>.
5076a392 2743
1e463951 2744=head3 C interface to C<caller()>
5076a392 2745
1e463951
FC
2746The C<caller_cx> function has been added as an XSUB-writer's equivalent of
2747C<caller()>. See L<perlapi> for details.
5076a392 2748
1e463951 2749=head3 Custom per-subroutine check hooks
5076a392 2750
1e463951
FC
2751XS code in an extension module can now annotate a subroutine (whether
2752implemented in XS or in Perl) so that nominated XS code will be called
2753at compile time (specifically as part of op checking) to change the op
2754tree of that subroutine. The compile-time check function (supplied by
2755the extension module) can implement argument processing that can't be
2756expressed as a prototype, generate customised compile-time warnings,
2757perform constant folding for a pure function, inline a subroutine
2758consisting of sufficiently simple ops, replace the whole call with a
2759custom op, and so on. This was previously all possible by hooking the
2760C<entersub> op checker, but the new mechanism makes it easy to tie the
2761hook to a specific subroutine. See L<perlapi/cv_set_call_checker>.
5076a392 2762
1e463951
FC
2763To help in writing custom check hooks, several subtasks within standard
2764C<entersub> op checking have been separated out and exposed in the API.
5076a392 2765
1e463951 2766=head3 Improved support for custom OPs
5076a392 2767
1e463951
FC
2768Custom ops can now be registered with the new C<custom_op_register> C
2769function and the C<XOP> structure. This will make it easier to add new
2770properties of custom ops in the future. Two new properties have been added
2771already, C<xop_class> and C<xop_peep>.
5076a392 2772
1e463951
FC
2773C<xop_class> is one of the OA_*OP constants, and allows L<B> and other
2774introspection mechanisms to work with custom ops
2775that aren't BASEOPs. C<xop_peep> is a pointer to
2776a function that will be called for ops of this
2777type from C<Perl_rpeep>.
5076a392 2778
1e463951
FC
2779See L<perlguts/Custom Operators> and L<perlapi/Custom Operators> for more
2780detail.
5076a392 2781
1e463951
FC
2782The old C<PL_custom_op_names>/C<PL_custom_op_descs> interface is still
2783supported but discouraged.
5076a392 2784
1e463951 2785=head3 Scope hooks
5076a392 2786
1e463951
FC
2787It is now possible for XS code to hook into Perl's lexical scope
2788mechanism at compile time, using the new C<Perl_blockhook_register>
2789function. See L<perlguts/"Compile-time scope hooks">.
5076a392 2790
1e463951 2791=head3 The recursive part of the peephole optimizer is now hookable
5076a392
FC
2792
2793In addition to C<PL_peepp>, for hooking into the toplevel peephole optimizer, a
2794C<PL_rpeepp> is now available to hook into the optimizer recursing into
2795side-chains of the optree.
2796
1e463951 2797=head3 New non-magical variants of existing functions
5076a392 2798
1e463951
FC
2799The following functions/macros have been added to the API. The C<*_nomg>
2800macros are equivalent to their non-_nomg variants, except that they ignore
2801get-magic. Those ending in C<_flags> allow one to specify whether
2802get-magic is processed.
5076a392 2803
1e463951
FC
2804 sv_2bool_flags
2805 SvTRUE_nomg
2806 sv_2nv_flags
2807 SvNV_nomg
2808 sv_cmp_flags
2809 sv_cmp_locale_flags
2810 sv_eq_flags
2811 sv_collxfrm_flags
5076a392 2812
1e463951 2813In some of these cases, the non-_flags functions have
5076a392
FC
2814been replaced with wrappers around the new functions.
2815
1e463951 2816=head3 pv/pvs/sv versions of existing functions
5076a392 2817
1e463951 2818Many functions ending with pvn now have equivalent pv/pvs/sv versions.
5076a392 2819
1e463951 2820=head3 List op-building functions
5076a392 2821
1e463951
FC
2822List op-building functions have been added to the
2823API. See L<op_append_elem|perlapi/op_append_elem>,
2824L<op_append_list|perlapi/op_append_list>, and
2825L<op_prepend_elem|perlapi/op_prepend_elem> in L<perlapi>.
5076a392 2826
1e463951 2827=head3 C<LINKLIST>
5076a392 2828
1e463951
FC
2829The L<LINKLIST|perlapi/LINKLIST> macro, part of op building that
2830constructs the execution-order op chain, has been added to the API.
5076a392 2831
1e463951 2832=head3 Localisation functions
5076a392 2833
1e463951
FC
2834The C<save_freeop>, C<save_op>, C<save_pushi32ptr> and C<save_pushptrptr>
2835functions have been added to the API.
5076a392 2836
1e463951 2837=head3 Stash names
5076a392 2838
1e463951
FC
2839A stash can now have a list of effective names in addition to its usual
2840name. The first effective name can be accessed via the C<HvENAME> macro,
2841which is now the recommended name to use in MRO linearisations (C<HvNAME>
2842being a fallback if there is no C<HvENAME>).
5076a392 2843
1e463951
FC
2844These names are added and deleted via C<hv_ename_add> and
2845C<hv_ename_delete>. These two functions are I<not> part of the API.
5076a392 2846
1e463951 2847=head3 New functions for finding and removing magic
5076a392 2848
1e463951
FC
2849The L<C<mg_findext()>|perlapi/mg_findext> and
2850L<C<sv_unmagicext()>|perlapi/sv_unmagicext>
2851functions have been added to the API.
2852They allow extension authors to find and remove magic attached to
2853scalars based on both the magic type and the magic virtual table, similar to how
2854C<sv_magicext()> attaches magic of a certain type and with a given virtual table
2855to a scalar. This eliminates the need for extensions to walk the list of
2856C<MAGIC> pointers of an C<SV> to find the magic that belongs to them.
5076a392 2857
1e463951 2858=head3 C<find_rundefsv>
5076a392 2859
1e463951
FC
2860This function returns the SV representing C<$_>, whether it's lexical
2861or dynamic.
5076a392 2862
1e463951 2863=head3 C<Perl_croak_no_modify>
5076a392 2864
1e463951
FC
2865C<Perl_croak_no_modify()> is short-hand for
2866C<Perl_croak("%s", PL_no_modify)>.
5076a392 2867
1e463951 2868=head3 C<PERL_STATIC_INLINE> define
5076a392 2869
1e463951
FC
2870The C<PERL_STATIC_INLINE> define has been added to provide the best-guess
2871incantation to use for static inline functions, if the C compiler supports
2872C99-style static inline. If it doesn't, it'll give a plain C<static>.
5076a392 2873
1e463951
FC
2874C<HAS_STATIC_INLINE> can be used to check if the compiler actually supports
2875inline functions.
5076a392 2876
1e463951 2877=head3 New C<pv_escape> option for hexadecimal escapes
5076a392 2878
1e463951
FC
2879A new option, C<PERL_PV_ESCAPE_NONASCII>, has been added to C<pv_escape> to
2880dump all characters above ASCII in hexadecimal. Before, one could get all
2881characters as hexadecimal or the Latin1 non-ASCII as octal.
5076a392 2882
1e463951 2883=head3 C<lex_start>
5076a392 2884
1e463951 2885C<lex_start> has been added to the API, but is considered experimental.
5076a392 2886
1e463951 2887=head3 C<op_scope()> and C<op_lvalue()>
5076a392 2888
1e463951
FC
2889The C<op_scope()> and C<op_lvalue()> functions have been added to the API,
2890but are considered experimental.
5076a392 2891
1e463951 2892=head2 C API Changes
5076a392 2893
1e463951 2894=head3 C<PERL_POLLUTE> has been removed
5076a392 2895
1e463951
FC
2896The option to define C<PERL_POLLUTE> to expose older 5.005 symbols for
2897backwards compatibility has been removed. It's use was always discouraged,
2898and MakeMaker contains a more specific escape hatch:
5076a392 2899
1e463951 2900 perl Makefile.PL POLLUTE=1
5076a392 2901
1e463951
FC
2902This can be used for modules that have not been upgraded to 5.6 naming
2903conventions (and really should be completely obsolete by now).
5076a392 2904
1e463951 2905=head3 Check API compatibility when loading XS modules
5076a392 2906
1e463951
FC
2907When perl's API changes in incompatible ways (which usually happens between
2908major releases), XS modules compiled for previous versions of perl will not
2909work anymore. They will need to be recompiled against the new perl.
5076a392 2910
1e463951
FC
2911In order to ensure that modules are recompiled, and to prevent users from
2912accidentally loading modules compiled for old perls into newer ones, the
2913C<XS_APIVERSION_BOOTCHECK> macro has been added. That macro, which is
2914called when loading every newly compiled extension, compares the API
2915version of the running perl with the version a module has been compiled for
2916and raises an exception if they don't match.
5076a392 2917
1e463951 2918=head3 Perl_fetch_cop_label
5076a392 2919
1e463951
FC
2920The first argument of the C API function C<Perl_fetch_cop_label> has changed
2921from C<struct refcounted he *> to C<COP *>, to insulate the user from
2922implementation details.
5076a392 2923
1e463951
FC
2924This API function was marked as "may change", and likely isn't in use outside
2925the core. (Neither an unpacked CPAN, nor Google's codesearch, finds any other
2926references to it.)
5076a392 2927
1e463951 2928=head3 GvCV() and GvGP() are no longer lvalues
5076a392 2929
1e463951
FC
2930The new GvCV_set() and GvGP_set() macros are now provided to replace
2931assignment to those two macros.
5076a392 2932
1e463951
FC
2933This allows a future commit to eliminate some backref magic between GV
2934and CVs, which will require complete control over assignment to the
2935gp_cv slot.
5076a392 2936
1e463951 2937=head3 CvGV() is no longer an lvalue
5076a392 2938
1e463951
FC
2939Under some circumstances, the C<CvGV()> field of a CV is now
2940reference-counted. To ensure consistent behaviour, direct assignment to
2941it, for example C<CvGV(cv) = gv> is now a compile-time error. A new macro,
2942C<CvGV_set(cv,gv)> has been introduced to perform this operation
2943safely. Note that modification of this field is not part of the public
2944API, regardless of this new macro (and despite its being listed in this section).
5076a392 2945
1e463951 2946=head3 CvSTASH() is no longer an lvalue
5076a392 2947
1e463951
FC
2948The C<CvSTASH()> macro can now only be used as an rvalue. C<CvSTASH_set()>
2949has been added to replace assignment to C<CvSTASH()>. This is to ensure
2950that backreferences are handled properly. These macros are not part of the
2951API.
5076a392 2952
1e463951 2953=head3 Calling conventions for C<newFOROP> and C<newWHILEOP>
5076a392 2954
1e463951
FC
2955The way the parser handles labels has been cleaned up and refactored. As a
2956result, the C<newFOROP()> constructor function no longer takes a parameter
2957stating what label is to go in the state op.
5076a392 2958
1e463951
FC
2959The C<newWHILEOP()> and C<newFOROP()> functions no longer accept a line
2960number as a parameter.
5076a392 2961
1e463951 2962=head3 Flags passed to C<uvuni_to_utf8_flags> and C<utf8n_to_uvuni>
5076a392 2963
1e463951
FC
2964Some of the flags parameters to uvuni_to_utf8_flags() and
2965utf8n_to_uvuni() have changed. This is a result of Perl's now allowing
5076a392
FC
2966internal storage and manipulation of code points that are problematic
2967in some situations. Hence, the default actions for these functions has
2968been complemented to allow these code points. The new flags are
2969documented in L<perlapi>. Code that requires the problematic code
483b16f3 2970points to be rejected needs to change to use the new flags. Some flag
5076a392
FC
2971names are retained for backward source compatibility, though they do
2972nothing, as they are now the default. However the flags
2973C<UNICODE_ALLOW_FDD0>, C<UNICODE_ALLOW_FFFF>, C<UNICODE_ILLEGAL>, and
2974C<UNICODE_IS_ILLEGAL> have been removed, as they stem from a
2975fundamentally broken model of how the Unicode non-character code points
2976should be handled, which is now described in
2977L<perlunicode/Non-character code points>. See also L</Selected Bug Fixes>.
2978
1e463951 2979XXX Which bugs in particular? Selected Bug Fixes is too long for this link
483b16f3
KW
2980to be meaningful right now
2981I don't see the bugs in that section currently -- khw
5076a392 2982
1e463951 2983=head2 Deprecated C APIs
5076a392 2984
1e463951 2985=over
5076a392 2986
1e463951 2987=item C<Perl_ptr_table_clear>
5076a392 2988
1e463951
FC
2989C<Perl_ptr_table_clear> is no longer part of Perl's public API. Calling it
2990now generates a deprecation warning, and it will be removed in a future
2991release.
5076a392 2992
1e463951 2993=item C<sv_compile_2op>
5076a392 2994
1e463951
FC
2995The C<sv_compile_2op()> API function is now deprecated. Searches suggest
2996that nothing on CPAN is using it, so this should have zero impact.
5076a392 2997
1e463951
FC
2998It attempted to provide an API to compile code down to an optree, but failed
2999to bind correctly to lexicals in the enclosing scope. It's not possible to
3000fix this problem within the constraints of its parameters and return value.
5076a392 3001
1e463951 3002=item C<find_rundefsvoffset>
5076a392 3003
1e463951
FC
3004The C<find_rundefsvoffset> function has been deprecated. It appeared that
3005its design was insufficient for reliably getting the lexical C<$_> at
3006run-time.
5076a392 3007
1e463951
FC
3008Use the new C<find_rundefsv> function or the C<UNDERBAR> macro
3009instead. They directly return the right SV representing C<$_>, whether it's
3010lexical or dynamic.
5076a392 3011
1e463951 3012=item C<CALL_FPTR> and C<CPERLscope>
5076a392 3013
1e463951
FC
3014Those are left from an old implementation of C<MULTIPLICITY> using C++ objects,
3015which was removed in Perl 5.8. Nowadays these macros do exactly nothing, so
3016they shouldn't be used anymore.
5076a392 3017
1e463951
FC
3018For compatibility, they are still defined for external C<XS> code. Only
3019extensions defining C<PERL_CORE> must be updated now.
5076a392 3020
1e463951 3021=back
5076a392 3022
1e463951 3023=head2 Other Internal Changes
5076a392 3024
1e463951 3025=head3 Stack unwinding
5076a392 3026
1e463951
FC
3027The protocol for unwinding the C stack at the last stage of a C<die>
3028has changed how it identifies the target stack frame. This now uses
3029a separate variable C<PL_restartjmpenv>, where previously it relied on
3030the C<blk_eval.cur_top_env> pointer in the C<eval> context frame that
3031has nominally just been discarded. This change means that code running
3032during various stages of Perl-level unwinding no longer needs to take
3033care to avoid destroying the ghost frame.
5076a392 3034
1e463951 3035=head3 Scope stack entries
5076a392 3036
1e463951
FC
3037The format of entries on the scope stack has been changed, resulting in a
3038reduction of memory usage of about 10%. In particular, the memory used by
3039the scope stack to record each active lexical variable has been halved.
5076a392 3040
1e463951 3041=head3 Memory allocation for pointer tables
5076a392 3042
1e463951
FC
3043Memory allocation for pointer tables has been changed. Previously
3044C<Perl_ptr_table_store> allocated memory from the same arena system as
3045C<SV> bodies and C<HE>s, with freed memory remaining bound to those arenas
3046until interpreter exit. Now it allocates memory from arenas private to the
3047specific pointer table, and that memory is returned to the system when
3048C<Perl_ptr_table_free> is called. Additionally, allocation and release are
3049both less CPU intensive.
5076a392 3050
1e463951 3051=head3 C<UNDERBAR>
5076a392 3052
1e463951
FC
3053The C<UNDERBAR> macro now calls C<find_rundefsv>. C<dUNDERBAR> is now a
3054noop but should still be used to ensure past and future compatibility.
5076a392 3055
1e463951 3056=head3 String comparison routines renamed
5076a392 3057
1e463951
FC
3058The ibcmp_* functions have been renamed and are now called foldEQ,
3059foldEQ_locale and foldEQ_utf8. The old names are still available as
3060macros.
3061
3062=head3 C<chop> and C<chomp> implementations merged
3063
3064The opcode bodies for C<chop> and C<chomp> and for C<schop> and C<schomp>
3065have been merged. The implementation functions C<Perl_do_chop()> and
3066C<Perl_do_chomp()>, never part of the public API, have been merged and
3067moved to a static function in F<pp.c>. This shrinks the perl binary
3068slightly, and should not affect any code outside the core (unless it is
3069relying on the order of side effects when C<chomp> is passed a I<list> of
3070values).
5076a392
FC
3071
3072=head1 Selected Bug Fixes
3073
e8e35311
FC
3074=head2 I/O
3075
5076a392
FC
3076=over 4
3077
3078=item *
3079
e8e35311 3080Perl no longer produces this warning:
a593b319
FC
3081
3082 $ perl -we 'open my $f, ">", \my $x; binmode $f, "scalar"'
3083 Use of uninitialized value in binmode at -e line 1.
3084
3085=item *
3086
e8e35311
FC
3087Opening a glob reference via C<< open $fh, "E<gt>", \*glob >> will no longer
3088cause the glob to be corrupted when the filehandle is printed to. This would
3089cause perl to crash whenever the glob's contents were accessed
3090[perl #77492].
4ed2cea4
FC
3091
3092=item *
3093
e8e35311
FC
3094PerlIO no longer crashes when called recursively, e.g., from a signal
3095handler. Now it just leaks memory [perl #75556].
4ed2cea4
FC
3096
3097=item *
3098
e8e35311
FC
3099Most I/O functions were not warning for unopened handles unless the
3100'closed' and 'unopened' warnings categories were both enabled. Now only
3101C<use warnings 'unopened'> is necessary to trigger these warnings (as was
438c239f 3102always meant to be the case).
4ed2cea4
FC
3103
3104=item *
3105
438c239f 3106There have been several fixes to PerlIO layers:
e8e35311 3107
438c239f
FC
3108When C<binmode FH, ":crlf"> pushes the C<:crlf> layer on top of the stack,
3109it no longer enables crlf layers lower in the stack, to avoid unexpected
3110results [perl #38456].
4ed2cea4 3111
438c239f
FC
3112Opening a file in C<:raw> mode now does what it advertises to do (first
3113open the file, then binmode it), instead of simply leaving off the top
3114layer [perl #80764].
5076a392 3115
438c239f
FC
3116The three layers C<:pop>, C<:utf8> and C<:bytes> didn't allow stacking when
3117opening a file. For example
e8e35311 3118this:
5076a392 3119
e8e35311 3120 open FH, '>:pop:perlio', 'some.file' or die $!;
5076a392 3121
438c239f
FC
3122Would throw an error: "Invalid argument". This has been fixed in this
3123release [perl #82484].
5076a392 3124
e8e35311
FC
3125=back
3126
3127=head2 Regular Expression Bug Fixes
3128
3129=over
5076a392
FC
3130
3131=item *
3132
e8e35311
FC
3133The regular expression engine no longer loops when matching
3134C<"\N{LATIN SMALL LIGATURE FF}" =~ /f+/i> and similar expressions
cdc10f43 3135[perl #72998] (5.12.1).
5076a392
FC
3136
3137=item *
3138
e8e35311
FC
3139The trie runtime code should no longer allocate massive amounts of memory,
3140fixing #74484.
5076a392
FC
3141
3142=item *
3143
438c239f
FC
3144Syntax errors in C<< (?{...}) >> blocks no longer cause panic messages
3145[perl #2353].
5076a392
FC
3146
3147=item *
3148
438c239f
FC
3149A pattern like C<(?:(o){2})?> no longer causes a "panic" error
3150[perl #39233].
5076a392
FC
3151
3152=item *
3153
438c239f 3154A fatal error in regular expressions containing C<(.*?)> when processing
d430b8e7 3155UTF-8 data has been fixed [perl #75680] (5.12.2).
5076a392
FC
3156
3157=item *
3158
e8e35311 3159An erroneous regular expression engine optimisation that caused regex verbs like
438c239f 3160C<*COMMIT> sometimes to be ignored has been removed.
5076a392
FC
3161
3162=item *
3163
e8e35311
FC
3164The regular expression bracketed character class C<[\8\9]> was effectively the
3165same as C<[89\000]>, incorrectly matching a NULL character. It also gave
3166incorrect warnings that the C<8> and C<9> were ignored. Now C<[\8\9]> is the
3167same as C<[89]> and gives legitimate warnings that C<\8> and C<\9> are
3168unrecognized escape sequences, passed-through.
5076a392
FC
3169
3170=item *
3171
e8e35311
FC
3172A regular expression match in the right-hand side of a global substitution
3173(C<s///g>) that is in the same scope will no longer cause match variables
3174to have the wrong values on subsequent iterations. This can happen when an
3175array or hash subscript is interpolated in the right-hand side, as in
3176C<s|(.)|@a{ print($1), /./ }|g> [perl #19078].
5076a392
FC
3177
3178=item *
3179
438c239f
FC
3180Several cases in which characters in the Latin-1 non-ASCII range (0x80 to
31810xFF) used not to match themselves or used to match both a character class
3182and its complement have been fixed. For instance, U+00E2 could match both
3183C<\w> and C<\W> [perl #78464] [perl #18281] [perl #60156].
5076a392
FC
3184
3185=item *
3186
e8e35311
FC
3187Matching a Unicode character against an alternation containing characters
3188that happened to match continuation bytes in the former's UTF8
3189representation (C<qq{\x{30ab}} =~ /\xab|\xa9/>) would cause erroneous
3190warnings [perl #70998].
5076a392
FC
3191
3192=item *
3193
e8e35311
FC
3194The trie optimisation was not taking empty groups into account, preventing
3195'foo' from matching C</\A(?:(?:)foo|bar|zot)\z/> [perl #78356].
5076a392
FC
3196
3197=item *
3198
e8e35311
FC
3199A pattern containing a C<+> inside a lookahead would sometimes cause an
3200incorrect match failure in a global match (e.g., C</(?=(\S+))/g>)
3201[perl #68564].
5076a392
FC
3202
3203=item *
3204
e8e35311
FC
3205A regular expression optimisation would sometimes cause a match with a
3206C<{n,m}> quantifier to fail when it should match [perl #79152].
5076a392
FC
3207
3208=item *
3209
e8e35311 3210Case insensitive matching in regular expressions compiled under C<use
438c239f
FC
3211locale> now works much more sanely when the pattern or
3212target string is encoded internally in
3213UTF8. Previously, under these conditions the localeness
e8e35311
FC
3214was completely lost. Now, code points above 255 are treated as Unicode,
3215but code points between 0 and 255 are treated using the current locale
438c239f
FC
3216rules, regardless of whether the pattern or the string is encoded in UTF8.
3217The few case-insensitive matches that cross the 255/256 boundary are not
e8e35311
FC
3218allowed. For example, 0xFF does not caselessly match the character at
32190x178, LATIN CAPITAL LETTER Y WITH DIAERESIS, because 0xFF may not be
3220LATIN SMALL LETTER Y in the current locale, and Perl has no way of
3221knowing if that character even exists in the locale, much less what code
3222point it is.
5076a392
FC
3223
3224=item *
3225
e8e35311
FC
3226The C<(?|...)> regular expression construct no longer crashes if the final
3227branch has more sets of capturing parentheses than any other branch. This
3228was fixed in Perl 5.10.1 for the case of a single branch, but that fix did
3229not take multiple branches into account [perl #84746].
5076a392
FC
3230
3231=item *
3232
e8e35311
FC
3233A bug has been fixed in the implementation of C<{...}> quantifiers in
3234regular expressions that prevented the code block in
3235C</((\w+)(?{ print $2 })){2}/> from seeing the C<$2> sometimes
3236[perl #84294].
5076a392 3237
e8e35311 3238=back
5076a392 3239
e8e35311
FC
3240=head2 Syntax/Parsing Bugs
3241
3242=over
5076a392
FC
3243
3244=item *
3245
e8e35311 3246C<when(scalar){...}> no longer crashes, but produces a syntax error
cdc10f43 3247[perl #74114] (5.12.1).
5076a392
FC
3248
3249=item *
3250
e8e35311
FC
3251A label right before a string eval (C<foo: eval $string>) no longer causes
3252the label to be associated also with the first statement inside the eval
3253[perl #74290] (5.12.1).
5076a392
FC
3254
3255=item *
3256
b2c076b5 3257The C<no 5.13.2;> form of C<no> no longer tries to turn on features or
d430b8e7 3258pragmata (i.e., strict) [perl #70075] (5.12.2).
5076a392
FC
3259
3260=item *
3261
b2c076b5
FC
3262C<BEGIN {require 5.12.0}> now behaves as documented, rather than behaving
3263identically to C<use 5.12.0;>. Previously, C<require> in a C<BEGIN> block
3264was erroneously executing the C<use feature ':5.12.0'> and
3265C<use strict;> behaviour, which only C<use> was documented to
3266provide [perl #69050].
5076a392
FC
3267
3268=item *
3269
5076a392
FC
3270A regression introduced in Perl 5.12.0, making
3271C<< my $x = 3; $x = length(undef) >> result in C<$x> set to C<3> has been
d430b8e7 3272fixed. C<$x> will now be C<undef> [perl #85508] (5.12.2).
b2c076b5
FC
3273
3274=item *
3275
3276When strict 'refs' mode is off, C<%{...}> in rvalue context returns
3277C<undef> if its argument is undefined. An optimisation introduced in perl
32785.12.0 to make C<keys %{...}> faster when used as a boolean did not take
3279this into account, causing C<keys %{+undef}> (and C<keys %$foo> when
3280C<$foo> is undefined) to be an error, which it should only be in strict
3281mode [perl #81750].
5076a392
FC
3282
3283=item *
3284
e8e35311 3285Constant-folding used to cause
5076a392 3286
e8e35311 3287 $text =~ ( 1 ? /phoo/ : /bear/)
5076a392 3288
e8e35311
FC
3289to turn into
3290
3291 $text =~ /phoo/
3292
3293at compile time. Now it correctly matches against C<$_> [perl #20444].
5076a392
FC
3294
3295=item *
3296
e8e35311
FC
3297Parsing Perl code (either with string C<eval> or by loading modules) from
3298within a C<UNITCHECK> block no longer causes the interpreter to crash
3299[perl #70614].
5076a392
FC
3300
3301=item *
3302
b2c076b5
FC
3303String evals no longer fail after 2 billion scopes have been
3304compiled [perl #83364].
3305
3306=item *
3307
e8e35311
FC
3308The parser no longer hangs when encountering certain Unicode characters,
3309such as U+387 [perl #74022].
5076a392
FC
3310
3311=item *
3312
b2c076b5
FC
3313Several contexts no longer allow a Unicode character to begin a word
3314that should never begin words, for an example an accent that must follow
3315another character previously could precede all other characters.
5076a392
FC
3316
3317=item *
3318
e8e35311
FC
3319Defining a constant with the same name as one of perl's special blocks
3320(e.g., INIT) stopped working in 5.12.0, but has now been fixed
3321[perl #78634].
5076a392
FC
3322
3323=item *
3324
e8e35311
FC
3325A reference to a literal value used as a hash key (C<$hash{\"foo"}>) used
3326to be stringified, even if the hash was tied [perl #79178].
5076a392
FC
3327
3328=item *
3329
e8e35311
FC
3330A closure containing an C<if> statement followed by a constant or variable
3331is no longer treated as a constant [perl #63540].
5076a392
FC
3332
3333=item *
3334
e8e35311
FC
3335C<state> can now be used with attributes. It used to mean the same thing as
3336C<my> if attributes were present [perl #68658].
5076a392
FC
3337
3338=item *
3339
e8e35311
FC
3340Expressions like C<< @$a > 3 >> no longer cause C<$a> to be mentioned in
3341the "Use of uninitialized value in numeric gt" warning when C<$a> is
3342undefined (since it is not part of the C<E<gt>> expression, but the operand
3343of the C<@>) [perl #72090].
5076a392
FC
3344
3345=item *
3346
e8e35311
FC
3347Accessing an element of a package array with a hard-coded number (as
3348opposed to an arbitrary expression) would crash if the array did not exist.
3349Usually the array would be autovivified during compilation, but typeglob
3350manipulation could remove it, as in these two cases which used to crash:
5076a392 3351
e8e35311
FC
3352 *d = *a; print $d[0];
3353 undef *d; print $d[0];
5076a392 3354
2c389f6c
FC
3355=item *
3356
3357The C<-C> command line option, when used on the shebang line, can now be
3358followed by other options [perl #72434].
3359
3360=item *
3361
3362The C<B> module was returning C<B::OP>s instead of C<B::LOGOP>s for C<entertry> [perl #80622].
3363This was due to a bug in the perl core, not in C<B> itself.
3364
e8e35311 3365=back
5076a392 3366
e262cb24
FC
3367=head2 Stashes, Globs and Method Lookup
3368
3369Perl 5.10.0 introduced a new internal mechanism for caching MROs (method
3370resolution orders, or lists of parent classes; aka "isa" caches) to make
3371method lookup faster (so @ISA arrays would not have to be searched
3372repeatedly). Unfortunately, this brought with it quite a few bugs. Almost
3373all of these have been fixed now, along with a few MRO-related bugs that
3374existed before 5.10.0:
3375
3376=over
3377
3378=item *
3379
3380The following used to have erratic effects on method resolution, because
3381the "isa" caches were not reset or otherwise ended up listing the wrong
3382classes. These have been fixed.
3383
3384=over
3385
3386=item Aliasing packages by assigning to globs [perl #77358]
3387
3388=item Deleting packages by deleting their containing stash elements
3389
3390=item Undefining the glob containing a package (C<undef *Foo::>)
3391
3392=item Undefining an ISA glob (C<undef *Foo::ISA>)
3393
3394=item Deleting an ISA stash element (C<delete $Foo::{ISA}>)
3395
3396=item Sharing @ISA arrays between classes (via C<*Foo::ISA = \@Bar::ISA> or
3397C<*Foo::ISA = *Bar::ISA>) [perl #77238]
3398
3399=back
3400
3401C<undef *Foo::ISA> would even stop a new C<@Foo::ISA> array from updating
3402caches.
3403
3404=item *
3405
3406Typeglob assignments would crash if the glob's stash no longer existed, so
3407long as the glob assigned to was named 'ISA' or the glob on either side of
3408the assignment contained a subroutine.
3409
3410=item *
3411
3412C<PL_isarev>, which is accessible to Perl via C<mro::get_isarev> is now
3413updated properly when packages are deleted or removed from the C<@ISA> of
3414other classes. This allows many packages to be created and deleted without
3415causing a memory leak [perl #75176].
3416
3417=back
3418
3419In addition, various other bugs related to typeglobs and stashes have been
3420fixed:
5076a392 3421
e8e35311 3422=over
5076a392
FC
3423
3424=item *
3425
e8e35311 3426Some work has been done on the internal pointers that link between symbol
e262cb24 3427tables (stashes), typeglobs and subroutines. This has the effect that
e8e35311
FC
3428various edge cases related to deleting stashes or stash entries (e.g.
3429<%FOO:: = ()>), and complex typeglob or code reference aliasing, will no
3430longer crash the interpreter.
5076a392
FC
3431
3432=item *
3433
e262cb24
FC
3434Assigning a reference to a glob copy now assigns to a glob slot instead of
3435overwriting the glob with a scalar [perl #1804] [perl #77508].
5076a392
FC
3436
3437=item *
3438
e8e35311
FC
3439A bug when replacing the glob of a loop variable within the loop has been fixed
3440[perl #21469]. This
3441means the following code will no longer crash:
5076a392 3442
e8e35311
FC
3443 for $x (...) {
3444 *x = *y;
3445 }
5076a392
FC
3446
3447=item *
3448
3449Assigning a glob to a PVLV used to convert it to a plain string. Now it
3450works correctly, and a PVLV can hold a glob. This would happen when a
3451nonexistent hash or array element was passed to a subroutine:
3452
3453 sub { $_[0] = *foo }->($hash{key});
3454 # $_[0] would have been the string "*main::foo"
3455
3456It also happened when a glob was assigned to, or returned from, an element
3457of a tied array or hash [perl #36051].
3458
3459=item *
44691e6f 3460
e8e35311 3461When trying to report C<Use of uninitialized value $Foo::BAR>, crashes could
e262cb24
FC
3462occur if the glob holding the global variable in question had been detached
3463from its original stash by, for example, C<delete $::{'Foo::'}>. This has
3464been fixed by disabling the reporting of variable names in those
e8e35311 3465cases.
44691e6f
AB
3466
3467=item *
3468
e8e35311
FC
3469During the restoration of a localised typeglob on scope exit, any
3470destructors called as a result would be able to see the typeglob in an
3471inconsistent state, containing freed entries, which could result in a
3472crash. This would affect code like this:
3473
3474 local *@;
3475 eval { die bless [] }; # puts an object in $@
3476 sub DESTROY {
3477 local $@; # boom
3478 }
3479
3480Now the glob entries are cleared before any destructors are called. This
3481also means that destructors can vivify entries in the glob. So perl tries
3482again and, if the entries are re-created too many times, dies with a
3483'panic: gp_free...' error message.
3484
3485=back
3486
3487=head2 Unicode
3488
3489=over
44691e6f 3490
5076a392 3491=item *
44691e6f 3492
e8e35311
FC
3493What has become known as the "Unicode Bug" is mostly resolved in this release.
3494Under C<use feature 'unicode_strings'>, the internal storage format of a
3495string no longer affects the external semantics. There are two known
3496exceptions. User-defined case changing functions, which are planned to
3497be deprecated in 5.14, require utf8-encoded strings to function; and the
3498character C<LATIN SMALL LETTER SHARP S> in regular expression
3499case-insensitive matching has a somewhat different set of bugs depending
3500on the internal storage format. Case-insensitive matching of all
3501characters that have multi-character matches, as this one does, is
3502problematical in Perl [perl #58182].
911a3729 3503
5076a392 3504=item *
c8c13991 3505
e8e35311
FC
3506The handling of Unicode non-characters has changed.
3507Previously they were mostly considered illegal, except that only one of
3508the 66 of them was known about in places. The Unicode standard
3509considers them legal, but forbids the "open interchange" of them.
3510This is part of the change to allow the internal use of any code point
3511(see L</Core Enhancements>). Together, these changes resolve
9a5a48b7
FC
3512[perl #38722], [perl #51918], [perl #51936], [perl #63446].
3513
3514=item *
3515
3516Naming a deprecated character in \N{...} no longer leaks memory.
3517
3518=item *
3519
cdc10f43
FC
3520We fixed a bug that could cause \N{} constructs followed by a single . to
3521be parsed incorrectly [perl #74978] (5.12.1).
3522
3523=item *
3524
9a5a48b7
FC
3525C<chop> now correctly handles characters above "\x{7fffffff}"
3526[perl #73246].
3527
3528=item *
3529
3530Passing to C<index> an offset beyond the end of the string when the string
3531is encoded internally in UTF8 no longer causes panics [perl #75898].
3532
3533=item *
3534
3535C<warn()> and C<die()> now respect utf8-encoded scalars [perl #45549].
c8c13991 3536
5076a392
FC
3537=item *
3538
9a5a48b7 3539Sometimes the UTF8 length cache would not be reset on a value
e8e35311 3540returned by substr, causing C<length(substr($uni_string,...))> to give
9a5a48b7
FC
3541wrong answers. With C<${^UTF8CACHE}> set to -1, it would produce a 'panic'
3542error message, too [perl #77692].
e8e35311
FC
3543
3544=back
3545
e9784f55 3546=head2 Ties, Overloading and Other Magic
e8e35311
FC
3547
3548=over
35cdccfc 3549
5076a392
FC
3550=item *
3551
e8e35311 3552Overloading now works properly in conjunction with tied
e9784f55 3553variables. What formerly happened was that most ops checked their
e8e35311
FC
3554arguments for overloading I<before> checking for magic, so for example
3555an overloaded object returned by a tied array access would usually be
e9784f55 3556treated as not overloaded [RT #57012].
911a3729 3557
5076a392 3558=item *
58f55cb3 3559
e9784f55
FC
3560Various cases of magic (e.g., tie methods) being called on tied variables
3561too many or too few times have been fixed:
3562
3563=over
58f55cb3 3564
5076a392 3565=item *
6b3df227