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perldelta: 5.12.3, not .2
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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
61752d82
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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
61752d82
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555Previously, a regular expression interpolated into another one inherited
556the localeness of the surrounding one, losing whatever state it
557originally had. This is considered a bug fix, but may trip up code that
558has come to rely on the incorrect behavior.
5076a392 559
61752d82 560=head3 Stringification of regexes has changed
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561
562Default regular expression modifiers are now notated by using
563C<(?^...)>. Code relying on the old stringification will fail. The
564purpose of this is so that when new modifiers are added, such code will
565not have to change (after this one time), as the stringification will
566automatically incorporate the new modifiers.
567
568Code that needs to work properly with both old- and new-style regexes
f318e2e6 569can avoid the whole issue by using (for Perls since 5.9.5; see L<re>):
5076a392
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570
571 use re qw(regexp_pattern);
572 my ($pat, $mods) = regexp_pattern($re_ref);
573
5076a392
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574If the actual stringification is important, or older Perls need to be
575supported, you can use something like the following:
576
577 # Accept both old and new-style stringification
578 my $modifiers = (qr/foobar/ =~ /\Q(?^/) ? '^' : '-xism';
579
580And then use C<$modifiers> instead of C<-xism>.
581
61752d82 582=head3 Run-time code blocks in regular expressions inherit pragmata
5076a392 583
61752d82
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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
61752d82
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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
61752d82
FC
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
FC
614C<defined %Foo::> now always returns true, even when no symbols have yet been
615defined in that package.
5076a392 616
61752d82
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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
5076a392
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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>.)
5076a392
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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<*$glob> on the second line returns a new immutable glob. That new
662glob is made an alias to C<*bar>. Then it is discarded. So the second
663assignment has no effect.
664
5076a392
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665See L<http://rt.perl.org/rt3/Public/Bug/Display.html?id=77810> for even
666more detail.
667
61752d82 668=head3 Clearing stashes
5076a392
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669
670Stash list assignment C<%foo:: = ()> used to make the stash anonymous
671temporarily while it was being emptied. Consequently, any of its
672subroutines referenced elsewhere would become anonymous (showing up as
673"(unknown)" in C<caller>). Now they retain their package names, such that
674C<caller> will return the original sub name if there is still a reference
675to its typeglob, or "foo::__ANON__" otherwise [perl #79208].
676
61752d82
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677=head3 Magic variables outside the main package
678
679In previous versions of Perl, magic variables like C<$!>, 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
5076a392
FC
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 $bar >> but will issue a warning.
5076a392 844
e683df94
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845=head2 C<\cI<X>>
846
847The backslash-c construct was designed as a way of specifying
848non-printable characters, but there were no restrictions (on ASCII
849platforms) on what the character following the C<c> could be. Now,
850a deprecation warning is raised if that character isn't an ASCII character.
851Also, a deprecation warning is raised for C<"\c{"> (which is the same
852as simply saying C<";">).
853
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854=head2 C<"\b{"> and C<"\B{">
855
856In regular expressions, a literal C<"{"> immediately following a C<"\b">
857(not in a bracketed character class) or a C<"\B{"> is now deprecated
858to allow for its future use by Perl itself.
859
5076a392
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860=head2 Deprecation warning added for deprecated-in-core .pl libs
861
862This is a mandatory warning, not obeying -X or lexical warning bits.
863The warning is modelled on that supplied by deprecate.pm for
864deprecated-in-core .pm libraries. It points to the specific CPAN
823d0e46
FC
865distribution that contains the .pl libraries. The CPAN version, of
866course, does not generate the warning.
5076a392
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867
868=head2 List assignment to C<$[>
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.
5076a392
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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:
5076a392
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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
FC
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)>.
bb5c3f11
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916It is planned to remove this feature in Perl 5.16. A CPAN module,
917L<Unicode::Casing>, providing improved functionality is being prepared for
918release by the time 5.14 is available.
823d0e46 919
18139a1b 920=head2 Deprecated modules
5076a392
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921
922The following modules will be removed from the core distribution in a
923future release, and should be installed from CPAN instead. Distributions
924on CPAN which require these should add them to their prerequisites. The
823d0e46 925core versions of these modules will issue a deprecation warning.
5076a392
FC
926
927If you ship a packaged version of Perl, either alone or as part of a
928larger system, then you should carefully consider the repercussions of
823d0e46 929core module deprecations. You may want to consider shipping your default
5076a392 930build of Perl with packages for some or all deprecated modules which
823d0e46 931install into C<vendor> or C<site> perl library directories. This will
5076a392
FC
932inhibit the deprecation warnings.
933
934Alternatively, you may want to consider patching F<lib/deprecate.pm>
935to provide deprecation warnings specific to your packaging system
936or distribution of Perl, consistent with how your packaging system
937or distribution manages a staged transition from a release where the
938installation of a single package provides the given functionality, to
939a later release where the system administrator needs to know to install
940multiple packages to get that same functionality.
941
942You can silence these deprecation warnings by installing the modules
943in question from CPAN. To install the latest version of all of them,
944just install C<Task::Deprecations::5_14>.
945
946=over
947
948=item L<Devel::DProf>
949
950We strongly recommend that you install and used L<Devel::NYTProf> in
951preference, as it offers significantly improved profiling and reporting.
952
953=back
954
5076a392
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955=head1 Performance Enhancements
956
54c7bb16 957=head2 "Safe signals" optimisation
df91d470
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958
959Signal dispatch has been moved from the runloop into control ops. This
960should give a few percent speed increase, and eliminates almost all of
961the speed penalty caused by the introduction of "safe signals" in
9625.8.0. Signals should still be dispatched within the same statement as
963they were previously - if this is not the case, or it is possible to
964create uninterruptible loops, this is a bug, and reports are encouraged
965of how to recreate such issues.
966
54c7bb16 967=head2 Optimisation of shift; and pop; calls without arguments
df91d470 968
111b6aa7
FC
969Two fewer OPs are used for shift and pop calls with no argument (with
970implicit C<@_>). This change makes C<shift;> 5% faster than C<shift @_;>
971on non-threaded perls and 25% faster on threaded.
df91d470 972
fa232254 973=head2 Optimisation of regexp engine string comparison work
df91d470 974
fa232254
FC
975The foldEQ_utf8 API function for case-insensitive comparison of strings (which
976is used heavily by the regexp engine) was substantially refactored and
977optimised - and its documentation much improved as a free bonus gift.
df91d470 978
fa232254 979=head2 Regular expression compilation speed-up
df91d470 980
fa232254
FC
981Compiling regular expressions has been made faster for the case where upgrading
982the regex to utf8 is necessary but that isn't known when the compilation begins.
df91d470 983
fa232254 984=head2 String appending is 100 times faster
df91d470 985
fa232254
FC
986When doing a lot of string appending, perl could end up allocating a lot more
987memory than needed in a very inefficient way, if perl was configured to use the
988system's C<malloc> implementation instead of its own.
989
990C<sv_grow>, which is what's being used to allocate more memory if necessary
991when appending to a string, has now been taught how to round up the memory
992it requests to a certain geometric progression, making it much faster on
993certain platforms and configurations. On Win32, it's now about 100 times
994faster.
995
996=head2 Eliminate C<PL_*> accessor functions under ithreads
997
998When C<MULTIPLICITY> was first developed, and interpreter state moved into
999an interpreter struct, thread and interpreter local C<PL_*> variables were
1000defined as macros that called accessor functions, returning the address of
1001the value, outside of the perl core. The intent was to allow members
1002within the interpreter struct to change size without breaking binary
1003compatibility, so that bug fixes could be merged to a maintenance branch
1004that necessitated such a size change.
1005
1006However, some non-core code defines C<PERL_CORE>, sometimes intentionally
1007to bypass this mechanism for speed reasons, sometimes for other reasons but
1008with the inadvertent side effect of bypassing this mechanism. As some of
1009this code is widespread in production use, the result is that the core
1010I<can't> change the size of members of the interpreter struct, as it will
1011break such modules compiled against a previous release on that maintenance
1012branch. The upshot is that this mechanism is redundant, and well-behaved
1013code is penalised by it. Hence it can and should be removed (and has
1014been).
1015
1016=head2 Freeing weak references
1017
1018When an object has many weak references to it, freeing that object
1019can under some some circumstances take O(N^2) time to free (where N is the
1020number of references). The number of circumstances has been reduced
1021[perl #75254]
1022
1023=head2 Lexical array and hash assignments
1024
1025An earlier optimisation to speed up C<my @array = ...> and
1026C<my %hash = ...> assignments caused a bug and was disabled in Perl 5.12.0.
1027
1028Now we have found another way to speed up these assignments [perl #82110].
df91d470 1029
111b6aa7 1030=head2 C<@_> uses less memory
df91d470 1031
111b6aa7
FC
1032Previously, C<@_> was allocated for every subroutine at compile time with
1033enough space for four entries. Now this allocation is done on demand when
1034the subroutine is called [perl #72416].
5076a392 1035
5076a392
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1036=head2 Size optimisations to SV and HV structures
1037
1038xhv_fill has been eliminated from struct xpvhv, saving 1 IV per hash and
111b6aa7 1039on some systems will cause struct xpvhv to become cache-aligned. To avoid
5076a392
FC
1040this memory saving causing a slowdown elsewhere, boolean use of HvFILL
1041now calls HvTOTALKEYS instead (which is equivalent) - so while the fill
111b6aa7
FC
1042data when actually required are now calculated on demand, the cases when
1043this needs to be done should be few and far between.
5076a392 1044
111b6aa7
FC
1045The order of structure elements in SV bodies has changed. Effectively,
1046the NV slot has swapped location with STASH and MAGIC. As all access to
1047SV members is via macros, this should be completely transparent. This
5076a392
FC
1048change allows the space saving for PVHVs documented above, and may reduce
1049the memory allocation needed for PVIVs on some architectures.
1050
fa232254
FC
1051C<XPV>, C<XPVIV>, and C<XPVNV> now only allocate the parts of the C<SV> body
1052they actually use, saving some space.
5076a392 1053
fa232254
FC
1054Scalars containing regular expressions now only allocate the part of the C<SV>
1055body they actually use, saving some space.
5076a392
FC
1056
1057=head2 Memory consumption improvements to Exporter
1058
1059The @EXPORT_FAIL AV is no longer created unless required, hence neither is
111b6aa7
FC
1060the typeglob backing it. This saves about 200 bytes for every package that
1061uses Exporter but doesn't use this functionality.
5076a392 1062
111b6aa7 1063=head2 Memory savings for weak references
5076a392
FC
1064
1065For weak references, the common case of just a single weak reference per
1066referent has been optimised to reduce the storage required. In this case it
111b6aa7 1067saves the equivalent of one small Perl array per referent.
5076a392 1068
111b6aa7 1069=head2 C<%+> and C<%-> use less memory
5076a392
FC
1070
1071The bulk of the C<Tie::Hash::NamedCapture> module used to be in the perl
111b6aa7 1072core. It has now been moved to an XS module, to reduce the overhead for
5076a392
FC
1073programs that do not use C<%+> or C<%->.
1074
fa232254 1075=head2 Multiple small improvements to threads
5076a392 1076
fa232254
FC
1077The internal structures of threading now make fewer API calls and fewer
1078allocations, resulting in noticeably smaller object code. Additionally,
1079many thread context checks have been deferred so that they're only done
1080when required (although this is only possible for non-debugging builds).
5076a392 1081
fa232254 1082=head2 Adjacent pairs of nextstate opcodes are now optimized away
5076a392 1083
fa232254 1084Previously, in code such as
5076a392 1085
fa232254 1086 use constant DEBUG => 0;
5076a392 1087
fa232254
FC
1088 sub GAK {
1089 warn if DEBUG;
1090 print "stuff\n";
1091 }
5076a392 1092
fa232254
FC
1093the ops for C<warn if DEBUG;> would be folded to a C<null> op (C<ex-const>), but
1094the C<nextstate> op would remain, resulting in a runtime op dispatch of
1095C<nextstate>, C<nextstate>, ....
5076a392 1096
fa232254
FC
1097The execution of a sequence of C<nextstate> ops is indistinguishable from just
1098the last C<nextstate> op so the peephole optimizer now eliminates the first of
1099a pair of C<nextstate> ops, except where the first carries a label, since labels
1100must not be eliminated by the optimizer and label usage isn't conclusively known
1101at compile time.
5076a392
FC
1102
1103=head1 Modules and Pragmata
1104
1105=head2 New Modules and Pragmata
1106
1107=over 4
1108
1109=item *
1110
1111C<CPAN::Meta::YAML> 0.003 has been added as a dual-life module. It supports a
1112subset of YAML sufficient for reading and writing META.yml and MYMETA.yml files
1113included with CPAN distributions or generated by the module installation
1114toolchain. It should not be used for any other general YAML parsing or
1115generation task.
1116
1117=item *
1118
1119C<CPAN::Meta> version 2.110440 has been added as a dual-life module. It
1120provides a standard library to read, interpret and write CPAN distribution
1121metadata files (e.g. META.json and META.yml) which describes a
1122distribution, its contents, and the requirements for building it and
1123installing it. The latest CPAN distribution metadata specification is
1124included as C<CPAN::Meta::Spec> and notes on changes in the specification
1125over time are given in C<CPAN::Meta::History>.
1126
1127=item *
1128
5a553547 1129C<HTTP::Tiny> 0.011 has been added as a dual-life module. It is a very
5076a392
FC
1130small, simple HTTP/1.1 client designed for simple GET requests and file
1131mirroring. It has has been added to enable CPAN.pm and CPANPLUS to
1132"bootstrap" HTTP access to CPAN using pure Perl without relying on external
1133binaries like F<curl> or F<wget>.
1134
1135=item *
1136
1137C<JSON::PP> 2.27105 has been added as a dual-life module, for the sake of
1138reading F<META.json> files in CPAN distributions.
1139
1140=item *
1141
1142C<Module::Metadata> 1.000003 has been added as a dual-life module. It gathers
1143package and POD information from Perl module files. It is a standalone module
1144based on Module::Build::ModuleInfo for use by other module installation
1145toolchain components. Module::Build::ModuleInfo has been deprecated in
1146favor of this module instead.
1147
1148=item *
1149
1150C<Perl::OSType> 1.002 has been added as a dual-life module. It maps Perl
1151operating system names (e.g. 'dragonfly' or 'MSWin32') to more generic types
1152with standardized names (e.g. "Unix" or "Windows"). It has been refactored
1153out of Module::Build and ExtUtils::CBuilder and consolidates such mappings into
1154a single location for easier maintenance.
1155
1156=item *
1157
1158The following modules were added by the C<Unicode::Collate>
1159upgrade. See below for details.
1160
1161C<Unicode::Collate::CJK::Big5>
1162
1163C<Unicode::Collate::CJK::GB2312>
1164
1165C<Unicode::Collate::CJK::JISX0208>
1166
1167C<Unicode::Collate::CJK::Korean>
1168
1169C<Unicode::Collate::CJK::Pinyin>
1170
1171C<Unicode::Collate::CJK::Stroke>
1172
1173=item *
1174
1175C<Version::Requirements> version 0.101020 has been added as a dual-life
1176module. It provides a standard library to model and manipulates module
1177prerequisites and version constraints as defined in the L<CPAN::Meta::Spec>.
1178
1179=back
1180
d622514a 1181=head2 Selected Module and Pragma Updates
5076a392
FC
1182
1183=over 4
1184
1185=item *
1186
5076a392
FC
1187C<Archive::Extract> has been upgraded from version 0.38 to 0.48.
1188
1189Updates since 0.38 include: a safe print method that guards
1190Archive::Extract from changes to $\; a fix to the tests when run in core
1984204c
FC
1191perl; support for TZ files; a modification for the lzma
1192logic to favour IO::Uncompress::Unlzma; and a fix
1193for an issue with NetBSD-current and its new unzip
5076a392
FC
1194executable.
1195
1196=item *
1197
1198C<Archive::Tar> has been upgraded from version 1.54 to 1.76.
1199
1984204c
FC
1200Important changes since 1.54 include the following:
1201
1202=over
1203
1204=item *
1205
1206Compatibility with busybox implementations of tar
1207
1208=item *
1209
1210A fix so that C<write()> and C<create_archive()>
1211close only handles they opened
1212
1213=item *
1214
1215A bug was fixed regarding the exit code of extract_archive.
5076a392 1216
1984204c
FC
1217=item *
1218
1219C<ptar> has a new option to allow safe
5076a392
FC
1220creation of tarballs without world-writable files on Windows, allowing those
1221archives to be uploaded to CPAN.
1222
1984204c
FC
1223=item *
1224
1225A new ptargrep utility for using regular expressions against
5076a392
FC
1226the contents of files in a tar archive.
1227
1984204c
FC
1228=item *
1229
1230Pax extended headers are now skipped.
1231
1232=back
5076a392
FC
1233
1234=item *
1235
5076a392
FC
1236C<B> has been upgraded from version 1.23 to 1.27.
1237
1238It no longer crashes when taking apart a C<y///> containing characters
1239outside the octet range or compiled in a C<use utf8> scope.
1240
1241The size of the shared object has been reduced by about 40%, with no
1242reduction in functionality.
1243
1244=item *
1245
1246C<B::Concise> has been upgraded from version 0.78 to 0.82.
1247
1248B::Concise marks rv2sv, rv2av and rv2hv ops with the new OPpDEREF flag
1249as "DREFed".
1250
1251It no longer produces mangled output with the C<-tree> option
1252[perl #80632].
1253
1254=item *
1255
5076a392
FC
1256C<B::Deparse> has been upgraded from version 0.96 to 1.02.
1257
1984204c 1258The deparsing of a nextstate op has changed when it has both a
5076a392
FC
1259change of package (relative to the previous nextstate), or a change of
1260C<%^H> or other state, and a label. Previously the label was emitted
cdc10f43 1261first, but now the label is emitted last (5.12.1).
5076a392 1262
5a553547
FC
1263The C<no 5.13.2> or similar form is now correctly handled by B::Deparse
1264(5.12.3).
5076a392
FC
1265
1266B::Deparse now properly handles the code that applies a conditional
1267pattern match against implicit C<$_> as it was fixed in [perl #20444].
1268
1984204c
FC
1269Deparsing of C<our> followed by a variable with funny characters
1270(as permitted under the C<utf8> pragma) has also been fixed [perl #33752].
5076a392
FC
1271
1272=item *
1273
d430b8e7 1274C<Carp> has been upgraded from version 1.15 to 1.19.
5076a392
FC
1275
1276L<Carp> now detects incomplete L<caller()|perlfunc/"caller EXPR"> overrides and
d430b8e7
FC
1277avoids using bogus C<@DB::args>. To provide backtraces,
1278Carp relies on particular behaviour of the C<caller>
1279built-in. Carp now detects if other code has
5076a392 1280overridden this with an incomplete implementation, and modifies its backtrace
d430b8e7
FC
1281accordingly. Previously incomplete overrides would cause incorrect values
1282in backtraces (best case), or obscure fatal errors (worst case).
5076a392
FC
1283
1284This fixes certain cases of C<Bizarre copy of ARRAY> caused by modules
d430b8e7 1285overriding C<caller()> incorrectly (5.12.2).
5076a392 1286
1984204c 1287It now also avoids using regular expressions that cause perl to
5076a392
FC
1288load its Unicode tables, in order to avoid the 'BEGIN not safe after
1289errors' error that will ensue if there has been a syntax error
1290[perl #82854].
1291
1292=item *
1293
1294C<CGI> has been upgraded from version 3.48 to 3.51.
1295
1296This provides the following security fixes: the MIME boundary in
1984204c
FC
1297multipart_init is now random and the handling of
1298newlines embedded in header values has been improved.
5076a392
FC
1299
1300=item *
1301
5076a392
FC
1302C<Compress::Raw::Bzip2> has been upgraded from version 2.024 to 2.033.
1303
1984204c 1304It has been updated to use bzip2 1.0.6.
5076a392
FC
1305
1306=item *
1307
1984204c
FC
1308C<CPAN> has been upgraded from version 1.94_56 to 1.9600.-
1309
1310Major highlights:
5076a392
FC
1311
1312=over 4
1313
1984204c 1314=item * much less configuration dialog hassle
5076a392 1315
1984204c 1316=item * support for META/MYMETA.json
5076a392 1317
1984204c 1318=item * support for local::lib
5076a392 1319
1984204c 1320=item * support for HTTP::Tiny to reduce the dependency on ftp sites
5076a392 1321
1984204c 1322=item * automatic mirror selection
5076a392 1323
1984204c 1324=item * iron out all known bugs in configure_requires
5076a392 1325
1984204c
FC
1326=item * support for distributions compressed with bzip2
1327
1328=item * allow Foo/Bar.pm on the commandline to mean Foo::Bar
1329
1330=back
5076a392
FC
1331
1332=item *
1333
d430b8e7
FC
1334C<CPANPLUS> has been upgraded from version 0.90 to 0.9103.
1335
1336A change to F<cpanp-run-perl>
1337resolves L<RT #55964|http://rt.cpan.org/Public/Bug/Display.html?id=55964>
1338and L<RT #57106|http://rt.cpan.org/Public/Bug/Display.html?id=57106>, both
1339of which related to failures to install distributions that use
1340C<Module::Install::DSL> (5.12.2).
5076a392 1341
1984204c
FC
1342A dependency on Config was not recognised as a
1343core module dependency. This has been fixed.
5076a392 1344
1984204c 1345CPANPLUS now includes support for META.json and MYMETA.json.
5076a392
FC
1346
1347=item *
1348
5076a392
FC
1349C<Data::Dumper> has been upgraded from version 2.125 to 2.130_02.
1350
4ed2cea4
FC
1351The indentation used to be off when C<$Data::Dumper::Terse> was set. This
1352has been fixed [perl #73604].
1353
1984204c
FC
1354This upgrade also fixes a crash when using custom sort functions that might
1355cause the stack to change [perl #74170].
5076a392
FC
1356
1357C<Dumpxs> no longer crashes with globs returned by C<*$io_ref>
1358[perl #72332].
1359
1360=item *
1361
5076a392
FC
1362C<Devel::DProf> has been upgraded from version 20080331.00 to 20110228.00.
1363
1364Merely loading C<Devel::DProf> now no longer triggers profiling to start.
1365C<use Devel::DProf> and C<perl -d:DProf ...> still behave as before and start
1366the profiler.
1367
1368NOTE: C<Devel::DProf> is deprecated and will be removed from a future
1984204c 1369version of Perl. We strongly recommend that you install and use
5076a392
FC
1370L<Devel::NYTProf> instead, as it offers significantly improved
1371profiling and reporting.
1372
1373=item *
1374
5076a392
FC
1375C<diagnostics> has been upgraded from version 1.19 to 1.22.
1376
1377It now renders pod links slightly better, and has been taught to find
1378descriptions for messages that share their descriptions with other
1379messages.
1380
1381=item *
1382
1383C<Digest::MD5> has been upgraded from version 2.39 to 2.51.
1384
1385It is now safe to use this module in combination with threads.
1386
1387=item *
1388
1389C<Digest::SHA> has been upgraded from version 5.47 to 5.61.
1390
1391C<shasum> now more closely mimics C<sha1sum>/C<md5sum>.
1392
1393C<Addfile> accepts all POSIX filenames.
1394
1984204c
FC
1395New SHA-512/224 and SHA-512/256 transforms (ref. NIST Draft FIPS 180-4
1396[February 2011])
5076a392
FC
1397
1398=item *
1399
5076a392
FC
1400C<DynaLoader> has been upgraded from version 1.10 to 1.12.
1401
1402It fixes a buffer overflow when passed a very long file name.
1403
1404It no longer inherits from AutoLoader; hence it no longer
1405produces weird error messages for unsuccessful method calls on classes that
1406inherit from DynaLoader [perl #84358].
1407
1408=item *
1409
1410C<Encode> has been upgraded from version 2.39 to 2.42.
1411
1412Now, all 66 Unicode non-characters are treated the same way U+FFFF has
1984204c
FC
1413always been treated; in cases when it was disallowed, all 66 are
1414disallowed; in those cases where it warned, all 66 warn.
5076a392
FC
1415
1416=item *
1417
5076a392
FC
1418C<Errno> has been upgraded from version 1.11 to 1.13.
1419
1420The implementation of C<Errno> has been refactored to use about 55% less memory.
5076a392
FC
1421
1422On some platforms with unusual header files, like Win32/gcc using mingw64
1423headers, some constants which weren't actually error numbers have been exposed
1424by C<Errno>. This has been fixed [perl #77416].
1425
1426=item *
1427
1428C<Exporter> has been upgraded from version 5.64_01 to 5.64_03.
1429
1430Exporter no longer overrides C<$SIG{__WARN__}> [perl #74472]
1431
1432=item *
1433
5076a392
FC
1434C<ExtUtils::Constant> has been upgraded from 0.22 to 0.23.
1435
1436The C<AUTOLOAD> helper code generated by C<ExtUtils::Constant::ProxySubs>
1437can now C<croak> for missing constants, or generate a complete C<AUTOLOAD>
1984204c
FC
1438subroutine in XS, allowing simplification of many modules that use it
1439(C<Fcntl>, C<File::Glob>, C<GDBM_File>, C<I18N::Langinfo>, C<POSIX>,
1440C<Socket>).
5076a392
FC
1441
1442C<ExtUtils::Constant::ProxySubs> can now optionally push the names of all
1984204c 1443constants onto the package's C<@EXPORT_OK>.
5076a392
FC
1444
1445=item *
1446
5076a392
FC
1447C<File::DosGlob> has been upgraded from version 1.01 to 1.03.
1448
1449It allows patterns containing literal parentheses (they no longer need to
1984204c
FC
1450be escaped). On Windows, it no longer
1451adds an extra F<./> to the file names
5076a392
FC
1452returned when the pattern is a relative glob with a drive specification,
1453like F<c:*.pl> [perl #71712].
1454
1455=item *
1456
1457C<File::Fetch> has been upgraded from version 0.24 to 0.32.
1458
1459C<HTTP::Lite> is now supported for 'http' scheme.
1460
1461The C<fetch> utility is supported on FreeBSD, NetBSD and
1462Dragonfly BSD for the C<http> and C<ftp> schemes.
1463
1464=item *
1465
1466C<File::Find> has been upgraded from version 1.15 to 1.18.
1467
1984204c 1468It improves handling of backslashes on Windows, so that paths like
5076a392
FC
1469F<c:\dir\/file> are no longer generated [perl #71710].
1470
1471=item *
1472
d430b8e7
FC
1473C<File::Spec> has been upgraded from version 3.31 to 3.33.
1474
1475Several portability fixes were made in C<File::Spec::VMS>: a colon is now
1476recognized as a delimiter in native filespecs; caret-escaped delimiters are
1477recognized for better handling of extended filespecs; C<catpath()> returns
1478an empty directory rather than the current directory if the input directory
1479name is empty; C<abs2rel()> properly handles Unix-style input (5.12.2).
1480
1481=item *
1482
5076a392
FC
1483C<File::stat> has been upgraded from 1.02 to 1.04.
1484
1485The C<-x> and C<-X> file test operators now work correctly under the root
1486user.
1487
1488=item *
1489
5076a392
FC
1490C<GDBM_File> has been upgraded from 1.10 to 1.13.
1491
1492This fixes a memory leak when DBM filters are used.
1493
1494=item *
1495
1496C<Hash::Util> has been upgraded from 0.07 to 0.10.
1497
1984204c
FC
1498Hash::Util no longer emits spurious "uninitialized" warnings when
1499recursively locking hashes that have undefined values [perl #74280].
5076a392
FC
1500
1501=item *
1502
1503C<I18N::Langinfo> has been upgraded from version 0.03 to 0.07.
1504
1505C<langinfo()> now defaults to using C<$_> if there is no argument given, just
5334145a 1506as the documentation has always claimed.
5076a392
FC
1507
1508=item *
1509
1510C<IO::Select> has been upgraded from version 1.17 to 1.18.
1511
1512It now allows IO::Handle objects (and objects in derived classes) to be
1513removed from an IO::Select set even if the underlying file descriptor is
1514closed or invalid.
1515
1516=item *
1517
5076a392
FC
1518C<IPC::Cmd> has been upgraded from version 0.54 to 0.68.
1519
1984204c
FC
1520Resolves an issue with splitting Win32 command lines. An argument
1521consisting of the single character "0" used to be omitted (CPAN RT #62961).
5076a392
FC
1522
1523=item *
1524
1525C<IPC::Open3> has been upgraded from 1.05 to 1.08.
1526
4ed2cea4
FC
1527C<open3> now produces an error if the C<exec> call fails, allowing this
1528condition to be distinguished from a child process that exited with a
1529non-zero status [perl #72016].
1530
5076a392
FC
1531The internal C<xclose> routine now knows how to handle file descriptors, as
1532documented, so duplicating STDIN in a child process using its file
1533descriptor now works [perl #76474].
1534
1535=item *
1536
5076a392
FC
1537C<Locale::Maketext> has been upgraded from version 1.14 to 1.17.
1538
1984204c 1539Locale::Maketext now supports external caches.
5076a392 1540
1984204c
FC
1541This upgrade also fixes an infinite loop in
1542C<Locale::Maketext::Guts::_compile()> when
5076a392
FC
1543working with tainted values (CPAN RT #40727).
1544
1984204c 1545C<< ->maketext >> calls will now back up and restore C<$@> so that error
5076a392
FC
1546messages are not suppressed (CPAN RT #34182).
1547
1548=item *
1549
5076a392
FC
1550C<Math::BigInt> has been upgraded from version 1.89_01 to 1.994.
1551
1552This fixes, among other things, incorrect results when computing binomial
1553coefficients [perl #77640].
1554
1984204c 1555It also prevents C<sqrt($int)> from crashing under C<use bigrat;>
5076a392
FC
1556[perl #73534].
1557
1558=item *
1559
5076a392
FC
1560C<MIME::Base64> has been upgraded from 3.08 to 3.13.
1561
1562Includes new functions to calculate the length of encoded and decoded
1563base64 strings.
1564
1565Now provides C<encode_base64url> and C<decode_base64url> functions to process
1566the base64 scheme for "URL applications".
1567
1568=item *
1569
1570C<Module::Build> has been upgraded from version 0.3603 to 0.3800.
1571
1572A notable change is the deprecation of several modules.
1573Module::Build::Version has been deprecated and Module::Build now relies
1574directly upon L<version>. Module::Build::ModuleInfo has been deprecated in
1575favor of a standalone copy of it called L<Module::Metadata>.
1576Module::Build::YAML has been deprecated in favor of L<CPAN::Meta::YAML>.
1577
1578Module::Build now also generates META.json and MYMETA.json files
1579in accordance with version 2 of the CPAN distribution metadata specification,
1580L<CPAN::Meta::Spec>. The older format META.yml and MYMETA.yml files are
1581still generated, as well.
1582
1583=item *
1584
1585C<Module::CoreList> has been upgraded from version 2.29 to XXX.
1586
1587Besides listing the updated core modules of this release, it also stops listing
1984204c 1588the C<Filespec> module. That module never existed in core. The scripts
5076a392 1589generating C<Module::CoreList> confused it with C<VMS::Filespec>, which actually
1984204c 1590is a core module as of perl 5.8.7.
5076a392
FC
1591
1592=item *
1593
1984204c
FC
1594C<NDBM_File> and C<ODBM_File> have been upgraded from 1.08 to 1.11, and
1595from 1.08 to 1.09, respectively.
5076a392
FC
1596
1597This fixes a memory leak when DBM filters are used.
1598
1599=item *
1600
5076a392
FC
1601C<overload> has been upgraded from 1.11 to 1.12.
1602
1603C<overload::Method> can now handle subroutines that are themselves blessed
1604into overloaded classes [perl #71998].
1605
5076a392
FC
1606The documentation has greatly improved. See L</Documentation> below.
1607
1608=item *
1609
5076a392
FC
1610C<Parse::CPAN::Meta> has been upgraded from version 1.40 to 1.4401.
1611
1984204c 1612The latest Parse::CPAN::Meta can now read YAML and JSON files using
5076a392
FC
1613L<CPAN::Meta::YAML> and L<JSON::PP>, which are now part of the Perl core.
1614
1615=item *
1616
5076a392
FC
1617C<PerlIO::scalar> has been upgraded from 0.07 to 0.11.
1618
1619A C<read> after a C<seek> beyond the end of the string no longer thinks it
1620has data to read [perl #78716].
1621
1622=item *
1623
5076a392
FC
1624C<POSIX> has been upgraded from 1.19 to 1.23.
1625
1626It now includes constants for POSIX signal constants.
1627
1628=item *
1629
1984204c 1630C<re> has been upgraded from version 0.11 to 0.17.
5076a392
FC
1631
1632New C<use re "/flags"> pragma
1633
5076a392 1634The C<regmust> function used to crash when called on a regular expression
1984204c 1635belonging to a pluggable engine. Now it croaks instead.
5076a392
FC
1636
1637C<regmust> no longer leaks memory.
1638
1639=item *
1640
1641C<Safe> has been upgraded from version 2.25 to 2.29.
1642
cdc10f43
FC
1643Coderefs returned by C<reval()> and C<rdo()> are now wrapped via
1644C<wrap_code_refs> (5.12.1).
1645
5076a392
FC
1646This fixes a possible infinite loop when looking for coderefs.
1647
cdc10f43 1648It adds several version::vxs::* routines to the default share.
5076a392
FC
1649
1650=item *
1651
5076a392
FC
1652C<SelfLoader> has been upgraded from 1.17 to 1.18.
1653
1654It now works in taint mode [perl #72062].
1655
1656=item *
1657
1658C<sigtrap> has been upgraded from version 1.04 to 1.05.
1659
1660It no longer tries to modify read-only arguments when generating a
1661backtrace [perl #72340].
1662
1663=item *
1664
1984204c 1665C<Socket> has been upgraded from version 1.87 to 1.94.
5076a392 1666
1984204c 1667See L</IPv6 support>, above.
5076a392
FC
1668
1669=item *
1670
1671C<Storable> has been upgraded from version 2.22 to 2.27.
1672
1673Includes performance improvement for overloaded classes.
1674
5076a392 1675This adds support for serialising code references that contain UTF-8 strings
1984204c
FC
1676correctly. The Storable minor version
1677number changed as a result, meaning that
5076a392
FC
1678Storable users who set C<$Storable::accept_future_minor> to a C<FALSE> value
1679will see errors (see L<Storable/FORWARD COMPATIBILITY> for more details).
1680
1681Freezing no longer gets confused if the Perl stack gets reallocated
1682during freezing [perl #80074].
1683
1684=item *
1685
5076a392
FC
1686C<Test::Simple> has been upgraded from version 0.94 to 0.98.
1687
1688Among many other things, subtests without a C<plan> or C<no_plan> now have an
1689implicit C<done_testing()> added to them.
1690
1691=item *
1692
5076a392
FC
1693C<Thread::Semaphore> has been upgraded from version 2.09 to 2.12.
1694
1984204c
FC
1695It provides two new methods that give more control over the decrementing of
1696semaphores: C<down_nb> and C<down_force>.
5076a392
FC
1697
1698=item *
1699
5076a392
FC
1700C<Tie::Hash> has been upgraded from version 1.03 to 1.04.
1701
1702Calling C<< Tie::Hash-E<gt>TIEHASH() >> used to loop forever. Now it C<croak>s.
1703
1704=item *
1705
5076a392
FC
1706C<Unicode::Collate> has been upgraded from version 0.52_01 to 0.73.
1707
1984204c 1708Unicode::Collate has been updated to use Unicode 6.0.0.
5076a392 1709
1984204c
FC
1710Unicode::Collate::Locale now supports a plethora of new locales: ar, be,
1711bg, de__phonebook, hu, hy, kk, mk, nso, om, tn, vi, hr, ig, ja, ko, ru, sq,
1712se, sr, to, uk, zh, zh__big5han, zh__gb2312han, zh__pinyin and zh__stroke.
5076a392
FC
1713
1714The following modules have been added:
1715
1716C<Unicode::Collate::CJK::Big5> for C<zh__big5han> which makes
1717tailoring of CJK Unified Ideographs in the order of CLDR's big5han ordering.
1718
1719C<Unicode::Collate::CJK::GB2312> for C<zh__gb2312han> which makes
1720tailoring of CJK Unified Ideographs in the order of CLDR's gb2312han ordering.
1721
1722C<Unicode::Collate::CJK::JISX0208> which makes tailoring of 6355 kanji
1723(CJK Unified Ideographs) in the JIS X 0208 order.
1724
1725C<Unicode::Collate::CJK::Korean> which makes tailoring of CJK Unified Ideographs
1726in the order of CLDR's Korean ordering.
1727
1728C<Unicode::Collate::CJK::Pinyin> for C<zh__pinyin> which makes
1729tailoring of CJK Unified Ideographs in the order of CLDR's pinyin ordering.
1730
1731C<Unicode::Collate::CJK::Stroke> for C<zh__stroke> which makes
1732tailoring of CJK Unified Ideographs in the order of CLDR's stroke ordering.
1733
5076a392
FC
1734This also sees the switch from using the pure-perl version of this
1735module to the XS version.
1736
1737=item *
1738
5076a392
FC
1739C<Unicode::UCD> has been upgraded from version 0.27 to 0.32.
1740
1984204c
FC
1741A new function, C<Unicode::UCD::num()>, has been added. This function
1742returns the numeric value of the string passed it or C<undef> if the string
1743in its entirety has no "safe" numeric value. (For more detail, and for the
1744definition of "safe", see L<Unicode::UCD/num>.)
5076a392 1745
1984204c 1746This upgrade also includes a number of bug fixes:
5076a392
FC
1747
1748=over 4
1749
1750=item charinfo()
1751
1752=over 4
1753
1754=item *
1755
1756It is now updated to Unicode Version 6 with Corrigendum #8, except,
1757as with Perl 5.14, the code point at U+1F514 has no name.
1758
1759=item *
1760
1761The Hangul syllable code points have the correct names, and their
1762decompositions are always output without requiring L<Lingua::KO::Hangul::Util>
1763to be installed.
1764
1765=item *
1766
54c7bb16
FC
1767The CJK (Chinese-Japanese-Korean) code points U+2A700 to U+2B734
1768and U+2B740 to U+2B81D are now properly handled.
5076a392
FC
1769
1770=item *
1771
1772The numeric values are now output for those CJK code points that have them.
1773
1774=item *
1775
1776The names that are output for code points with multiple aliases are now the
1777corrected ones.
1778
1779=back
1780
1781=item charscript()
1782
1783This now correctly returns "Unknown" instead of C<undef> for the script
1784of a code point that hasn't been assigned another one.
1785
1786=item charblock()
1787
1788This now correctly returns "No_Block" instead of C<undef> for the block
1789of a code point that hasn't been assigned to another one.
1790
1791=back
1792
5076a392
FC
1793=item *
1794
1795C<version> has been upgraded from 0.82 to 0.88.
1796
1984204c 1797Due to a bug, now fixed, the C<is_strict> and C<is_lax> functions did not
cdc10f43 1798work when exported (5.12.1).
5076a392
FC
1799
1800=item *
1801
1802C<warnings> and C<warnings::register> have been upgraded from version 1.09
1803to 1.11 and from version 1.01 to 1.02 respectively.
1804
1805Calling C<use warnings> without arguments is now significantly more efficient.
1806
1807It is now possible to register warning categories other than the names of
1808packages using C<warnings::register>. See L<perllexwarn> for more information.
1809
1810=item *
1811
1812C<VMS::DCLsym> has been upgraded from version 1.03 to 1.05.
1813
1814Two bugs have been fixed [perl #84086]:
1815
1816The symbol table name was lost when tying a hash, due to a thinko in
1817C<TIEHASH>. The result was that all tied hashes interacted with the
1818local symbol table.
1819
1820Unless a symbol table name had been explicitly specified in the call
1821to the constructor, querying the special key ':LOCAL' failed to
1822identify objects connected to the local symbol table.
1823
1824=item *
1825
1826C<Win32> has been upgraded from version 0.39 to 0.44.
1827
1984204c
FC
1828This release has several new functions: C<Win32::GetSystemMetrics>,
1829C<Win32::GetProductInfo>, C<Win32::GetOSDisplayName>.
5076a392 1830
1984204c
FC
1831The names returned by C<Win32::GetOSName> and C<Win32::GetOSDisplayName>
1832have been corrected.
5076a392 1833
5076a392
FC
1834=back
1835
5076a392
FC
1836=head2 Removed Modules and Pragmata
1837
1838The following modules have been removed from the core distribution, and if
1839needed should be installed from CPAN instead.
1840
1841=over
1842
1843=item C<Class::ISA>
1844
1845=item C<Pod::Plainer>
1846
1847=item C<Switch>
1848
1849=back
1850
1851The removal of C<Shell> has been deferred until after 5.14, as the
1852implementation of C<Shell> shipped with 5.12.0 did not correctly issue the
1853warning that it was to be removed from core.
1854
1855=head1 Documentation
1856
5076a392
FC
1857=head2 New Documentation
1858
41e29def 1859=head3 L<perlgpl>
5076a392
FC
1860
1861L<perlgpl> has been updated to contain GPL version 1, as is included in the
cdc10f43 1862F<README> distributed with perl (5.12.1).
5076a392 1863
41e29def 1864=head3 Perl 5.12.x delta files
5076a392 1865
41e29def
FC
1866The perldelta files for Perl 5.12.1 to 5.12.3 have been added from the
1867maintenance branch: L<perl5121delta>, L<perl5122delta>, L<perl5123delta>.
5076a392
FC
1868
1869=head3 L<perlpodstyle>
1870
1871New style guide for POD documentation,
1872split mostly from the NOTES section of the pod2man man page.
1873
41e29def
FC
1874=head3 L<perlsource>, L<perlinterp>, L<perlhacktut>, and L<perlhacktips>
1875
1876See L</L<perlhack> and perlrepository revamp>, below.
5076a392
FC
1877
1878=head2 Changes to Existing Documentation
1879
41e29def 1880=head3 L<perlmodlib> is now complete
4ed2cea4
FC
1881
1882The perlmodlib page that came with Perl 5.12.0 was missing a lot of
1883modules, due to a bug in the script that generates the list. This has been
cdc10f43 1884fixed [perl #74332] (5.12.1).
4ed2cea4 1885
41e29def 1886=head3 Replace wrong tr/// table in L<perlebcdic>
5076a392 1887
41e29def 1888L<perlebcdic> contains a helpful table to use in tr/// to convert
5076a392
FC
1889between EBCDIC and Latin1/ASCII. Unfortunately, the table was the
1890inverse of the one it describes, though the code that used the table
1891worked correctly for the specific example given.
1892
1893The table has been changed to its inverse, and the sample code changed
1894to correspond, as this is easier for the person trying to follow the
1895instructions since deriving the old table is somewhat more complicated.
1896
1897The table has also been changed to hex from octal, as that is more the norm
1898these days, and the recipes in the pod altered to print out leading
41e29def 1899zeros to make all the values the same length.
5076a392 1900
41e29def 1901=head3 Tricks for user-defined casing
5076a392 1902
41e29def
FC
1903L<perlunicode> now contains an explanation of how to override, mangle
1904and otherwise tweak the way perl handles upper-, lower- and other-case
1905conversions on Unicode data, and how to provide scoped changes to alter
1906one's own code's behaviour without stomping on anybody else.
5076a392
FC
1907
1908=head3 INSTALL explicitly states the requirement for C89
1909
d430b8e7
FC
1910This was already true but it's now Officially Stated For The Record
1911(5.12.2).
5076a392 1912
41e29def 1913=head3 Explanation of C<\xI<HH>> and C<\oI<OOO>> escapes
5076a392 1914
41e29def
FC
1915L<perlop> has been updated with more detailed explanation of these two
1916character escapes.
5076a392 1917
41e29def 1918=head3 C<-0I<NNN>> switch
5076a392 1919
41e29def 1920In L<perlrun>, the behavior of the C<-0NNN> switch for C<-0400> or higher
d430b8e7 1921has been clarified (5.12.2).
5076a392 1922
cdc10f43
FC
1923=head3 Maintenance policy
1924
1925L<perlpolicy> now contains the policy on what patches are acceptable for
1926maintenance branches (5.12.1).
1927
41e29def 1928=head3 Deprecation policy
5076a392 1929
41e29def 1930L<perlpolicy> now contains the policy on compatibility and deprecation
d430b8e7 1931along with definitions of terms like "deprecation" (5.12.2).
5076a392 1932
41e29def 1933=head3 New descriptions in L<perldiag>
5076a392
FC
1934
1935The following existing diagnostics are now documented:
1936
1937=over 4
1938
1939=item *
1940
1941L<Ambiguous use of %c resolved as operator %c|perldiag/"Ambiguous use of %c resolved as operator %c">
1942
1943=item *
1944
1945L<Ambiguous use of %c{%s} resolved to %c%s|perldiag/"Ambiguous use of %c{%s} resolved to %c%s">
1946
1947=item *
1948
1949L<Ambiguous use of %c{%s%s} resolved to %c%s%s|perldiag/"Ambiguous use of %c{%s%s} resolved to %c%s%s">
1950
1951=item *
1952
1953L<Ambiguous use of -%s resolved as -&%s()|perldiag/"Ambiguous use of -%s resolved as -&%s()">
1954
1955=item *
1956
1957L<Invalid strict version format (%s)|perldiag/"Invalid strict version format (%s)">
1958
1959=item *
1960
1961L<Invalid version format (%s)|perldiag/"Invalid version format (%s)">
1962
1963=item *
1964
1965L<Invalid version object|perldiag/"Invalid version object">
1966
1967=back
1968
5076a392
FC
1969=head3 L<perlbook>
1970
41e29def 1971L<perlbook> has been expanded to cover many more popular books.
5076a392 1972
41e29def 1973=head3 C<SvTRUE> macro
5076a392 1974
41e29def
FC
1975The documentation for the C<SvTRUE> macro in
1976L<perlapi> was simply wrong in stating that
5076a392
FC
1977get-magic is not processed. It has been corrected.
1978
41e29def 1979=head3 L<perlvar> revamp
5076a392 1980
41e29def 1981L<perlvar> reorders the variables and groups them by topic. Each variable
5076a392 1982introduced after Perl 5.000 notes the first version in which it is
41e29def 1983available. L<perlvar> also has a new section for deprecated variables to
5076a392
FC
1984note when they were removed.
1985
41e29def 1986=head3 Array and hash slices in scalar context
5076a392 1987
41e29def 1988These are now documented in L<perldata>.
5076a392 1989
41e29def 1990=head3 C<use locale> and formats
5076a392
FC
1991
1992L<perlform> and L<perllocale> have been corrected to state that
1993C<use locale> affects formats.
1994
5076a392
FC
1995=head3 L<overload>
1996
5076a392
FC
1997L<overload>'s documentation has practically undergone a rewrite. It
1998is now much more straightforward and clear.
1999
41e29def 2000=head3 L<perlhack> and perlrepository revamp
5076a392
FC
2001
2002The L<perlhack> and perlrepository documents have been heavily edited and
2003split up into several new documents.
2004
2005The L<perlhack> document is now much shorter, and focuses on the Perl 5
2006development process and submitting patches to Perl. The technical content has
2007been moved to several new documents, L<perlsource>, L<perlinterp>,
2008L<perlhacktut>, and L<perlhacktips>. This technical content has only been
2009lightly edited.
2010
2011The perlrepository document has been renamed to L<perlgit>. This new document
2012is just a how-to on using git with the Perl source code. Any other content
2013that used to be in perlrepository has been moved to perlhack.
2014
41e29def 2015=head3 Time::Piece examples
5076a392
FC
2016
2017Examples in L<perlfaq4> have been updated to show the use of
41e29def 2018L<Time::Piece>.
5076a392
FC
2019
2020=head1 Diagnostics
2021
2022The following additions or changes have been made to diagnostic output,
2023including warnings and fatal error messages. For the complete list of
2024diagnostic messages, see L<perldiag>.
2025
2026=head2 New Diagnostics
2027
a593b319
FC
2028=head3 New Errors
2029
5076a392
FC
2030=over
2031
a593b319 2032=item Closure prototype called
5076a392 2033
a593b319
FC
2034This error occurs when a subroutine reference passed to an attribute
2035handler is called, if the subroutine is a closure [perl #68560].
5076a392 2036
a593b319 2037=item Insecure user-defined property %s
5076a392 2038
a593b319
FC
2039Perl detected tainted data when trying to compile a regular
2040expression that contains a call to a user-defined character property
2041function, i.e. C<\p{IsFoo}> or C<\p{InFoo}>.
2042See L<perlunicode/User-Defined Character Properties> and L<perlsec>.
5076a392 2043
a593b319 2044=item panic: gp_free failed to free glob pointer - something is repeatedly re-creating entries
5076a392 2045
a593b319
FC
2046This new error is triggered if a destructor called on an object in a
2047typeglob that is being freed creates a new typeglob entry containing an
2048object with a destructor that creates a new entry containing an object....
5076a392 2049
a593b319 2050=item Parsing code internal error (%s)
5076a392 2051
a593b319
FC
2052This new fatal error is produced when parsing
2053code supplied by an extension violates the
2054parser's API in a detectable way.
5076a392 2055
a593b319 2056=item refcnt: fd %d%s
5076a392 2057
a593b319
FC
2058This new error only occurs if a internal consistency check fails when a
2059pipe is about to be closed.
5076a392 2060
a593b319 2061=item Regexp modifier "/%c" may not appear twice
5076a392 2062
a593b319
FC
2063The regular expression pattern has one of the
2064mutually exclusive modifiers repeated.
5076a392 2065
a593b319 2066=item Regexp modifiers "/%c" and "/%c" are mutually exclusive
5076a392 2067
a593b319
FC
2068The regular expression pattern has more than one of the mutually
2069exclusive modifiers.
5076a392 2070
a593b319 2071=item Using !~ with %s doesn't make sense
5076a392 2072
a593b319 2073This error occurs when C<!~> is used with C<s///r> or C<y///r>.
5076a392 2074
a593b319 2075=back
5076a392 2076
a593b319 2077=head3 New Warnings
5076a392 2078
a593b319 2079=over
5076a392 2080
a593b319 2081=item "\b{" is deprecated; use "\b\{" instead
5076a392 2082
a593b319 2083=item "\B{" is deprecated; use "\B\{" instead
5076a392 2084
a593b319
FC
2085Use of an unescaped "{" immediately following a C<\b> or C<\B> is now
2086deprecated so as to reserve its use for Perl itself in a future release.
5076a392 2087
a593b319 2088=item Operation "%s" returns its argument for ...
5076a392 2089
a593b319
FC
2090Performing an operation requiring Unicode semantics (such as case-folding)
2091on a Unicode surrogate or a non-Unicode character now triggers a warning:
2092'Operation "%s" returns its argument for ...'.
5076a392 2093
a593b319
FC
2094=item Use of qw(...) as parentheses is deprecated
2095
2096See L</"Use of qw(...) as parentheses">, above, for details.
5076a392
FC
2097
2098=back
2099
2100=head2 Changes to Existing Diagnostics
2101
2102=over 4
2103
2104=item *
2105
4ed2cea4
FC
2106The "Variable $foo is not imported" warning that precedes a
2107C<strict 'vars'> error has now been assigned the "misc" category, so that
2108C<no warnings> will suppress it [perl #73712].
2109
2110=item *
2111
5076a392
FC
2112C<warn> and C<die> now produce 'Wide character' warnings when fed a
2113character outside the byte range if STDERR is a byte-sized handle.
2114
2115=item *
2116
2117The 'Layer does not match this perl' error message has been replaced with
a593b319 2118these more helpful messages [perl #73754]:
5076a392
FC
2119
2120=over 4
2121
2122=item *
2123
2124PerlIO layer function table size (%d) does not match size expected by this
2125perl (%d)
2126
2127=item *
2128
2129PerlIO layer instance size (%d) does not match size expected by this perl
2130(%d)
2131
2132=back
2133
5076a392
FC
2134=item *
2135
2136The "Found = in conditional" warning that is emitted when a constant is
2137assigned to a variable in a condition is now withheld if the constant is
2138actually a subroutine or one generated by C<use constant>, since the value
2139of the constant may not be known at the time the program is written
2140[perl #77762].
2141
2142=item *
2143
2144Previously, if none of the C<gethostbyaddr>, C<gethostbyname> and
2145C<gethostent> functions were implemented on a given platform, they would
2146all die with the message 'Unsupported socket function "gethostent" called',
2147with analogous messages for C<getnet*> and C<getserv*>. This has been
2148corrected.
2149
2150=item *
2151
a593b319
FC
2152The warning message about unrecognized regular expression escapes passed
2153through has been changed to include any literal '{' following the
2154two-character escape. E.g., "\q{" is now emitted instead of "\q".
5076a392
FC
2155
2156=back
2157
2158=head1 Utility Changes
2159
0b88cc74 2160=head3 L<perlbug>
5076a392
FC
2161
2162=over 4
2163
2164=item *
2165
0b88cc74
FC
2166L<perlbug> now looks in the EMAIL environment variable for a return address
2167if the REPLY-TO and REPLYTO variables are empty.
5076a392
FC
2168
2169=item *
2170
0b88cc74
FC
2171L<perlbug> did not previously generate a From: header, potentially
2172resulting in dropped mail. Now it does include that header.
5076a392
FC
2173
2174=item *
2175
0b88cc74 2176The user's address is now used as the return-path.
4ed2cea4 2177
0b88cc74
FC
2178Many systems these days don't have a valid Internet domain name and
2179perlbug@perl.org does not accept email with a return-path that does
2180not resolve. So the user's address is now passed to sendmail so it's
2181less likely to get stuck in a mail queue somewhere [perl #82996].
5076a392 2182
2c389f6c
FC
2183=item *
2184
d430b8e7
FC
2185L<perlbug> now always gives the reporter a chance to change the email
2186address it guesses for them (5.12.2).
2187
2188=item *
2189
2190L<perlbug> should no longer warn about uninitialized values when using the C<-d>
2191and C<-v> options (5.12.2).
2c389f6c 2192
5076a392
FC
2193=back
2194
0b88cc74 2195=head3 L<perl5db.pl>
5076a392 2196
0b88cc74 2197=over
5076a392
FC
2198
2199=item *
2200
0b88cc74
FC
2201The remote terminal works after forking and spawns new sessions - one
2202for each forked process.
5076a392
FC
2203
2204=back
2205
0b88cc74 2206=head3 L<ptargrep>
5076a392
FC
2207
2208=over 4
2209
2210=item *
2211
0b88cc74
FC
2212L<ptargrep> is a new utility to apply pattern matching to the contents of
2213files in a tar archive. It comes with C<Archive::Tar>.
5076a392
FC
2214
2215=back
2216
2217=head1 Configuration and Compilation
2218
61752d82
FC
2219See also L</"Naming fixes in Policy_sh.SH may invalidate Policy.sh">,
2220above.
2221
5076a392
FC
2222=over 4
2223
2224=item *
2225
87595b22
FC
2226CCINCDIR and CCLIBDIR for the mingw64
2227cross-compiler are now correctly under
5076a392
FC
2228$(CCHOME)\mingw\include and \lib rather than immediately below $(CCHOME).
2229
5076a392
FC
2230This means the 'incpath', 'libpth', 'ldflags', 'lddlflags' and
2231'ldflags_nolargefiles' values in Config.pm and Config_heavy.pl are now
87595b22 2232set correctly.
5076a392
FC
2233
2234=item *
2235
87595b22
FC
2236'make test.valgrind' has been adjusted to account for cpan/dist/ext
2237separation.
5076a392
FC
2238
2239=item *
2240
2241On compilers that support it, C<-Wwrite-strings> is now added to cflags by
2242default.
2243
2244=item *
2245
2246The C<Encode> module can now (once again) be included in a static Perl
2247build. The special-case handling for this situation got broken in Perl
22485.11.0, and has now been repaired.
2249
1e463951
FC
2250=item *
2251
2252The previous default size of a PerlIO buffer (4096 bytes) has been increased
2253to the larger of 8192 bytes and your local BUFSIZ. Benchmarks show that doubling
2254this decade-old default increases read and write performance in the neighborhood
2255of 25% to 50% when using the default layers of perlio on top of unix. To choose
2256a non-default size, such as to get back the old value or to obtain an even
2257larger value, configure with:
2258
2259 ./Configure -Accflags=-DPERLIOBUF_DEFAULT_BUFSIZ=N
2260
2261where N is the desired size in bytes; it should probably be a multiple of
2262your page size.
2263
d430b8e7
FC
2264=item *
2265
2266An "incompatible operand types" error in ternary expressions when building
2267with C<clang> has been fixed (5.12.2).
2268
2269=item *
2270
2271Perl now skips setuid C<File::Copy> tests on partitions it detects to be mounted
2272as C<nosuid> (5.12.2).
2273
5076a392
FC
2274=back
2275
5076a392
FC
2276=head1 Platform Support
2277
5076a392
FC
2278=head2 New Platforms
2279
5076a392
FC
2280=over 4
2281
2282=item AIX
2283
cdc10f43 2284Perl now builds on AIX 4.2 (5.12.1).
5076a392
FC
2285
2286=back
2287
2288=head2 Discontinued Platforms
2289
2290=over 4
2291
5076a392
FC
2292=item Apollo DomainOS
2293
2294The last vestiges of support for this platform have been excised from the
2295Perl distribution. It was officially discontinued in version 5.12.0. It had
2296not worked for years before that.
2297
2298=item MacOS Classic
2299
2300The last vestiges of support for this platform have been excised from the
2301Perl distribution. It was officially discontinued in an earlier version.
2302
2303=back
2304
2305=head2 Platform-Specific Notes
2306
d430b8e7
FC
2307=head3 AIX
2308
2309=over
2310
2311=item *
2312
2313F<README.aix> has been updated with information about the XL C/C++ V11 compiler
2314suite (5.12.2).
2315
2316=back
2317
2318=head3 ARM
2319
2320=over
2321
2322=item *
2323
2324The C<d_u32align> configuration probe on ARM has been fixed (5.12.2).
2325
2326=back
2327
554003a2 2328=head3 Cygwin
5076a392
FC
2329
2330=over 4
2331
2332=item *
2333
554003a2 2334MakeMaker has been updated to build man pages on cygwin.
5076a392
FC
2335
2336=item *
2337
554003a2
FC
2338Improved rebase behaviour
2339
2340If a dll is updated on cygwin the old imagebase address is reused.
2341This solves most rebase errors, especially when updating on core dll's.
2342See L<http://www.tishler.net/jason/software/rebase/rebase-2.4.2.README> for more information.
5076a392
FC
2343
2344=item *
2345
554003a2 2346Support for the standard cygwin dll prefix, which is e.g. needed for FFI's
5076a392
FC
2347
2348=item *
2349
554003a2 2350Updated build hints file
5076a392
FC
2351
2352=back
2353
cdc10f43
FC
2354=head3 FreeBSD 7
2355
2356=over
2357
2358=item *
2359
2360FreeBSD 7 no longer contains F</usr/bin/objformat>. At build time,
2361Perl now skips the F<objformat> check for versions 7 and higher and
2362assumes ELF (5.12.1).
2363
2364=back
2365
2366=head3 HP-UX
2367
2368=over
2369
2370=item *
2371
2372Perl now allows -Duse64bitint without promoting to use64bitall on HP-UX
2373(5.12.1).
2374
2375=back
2376
554003a2 2377=head3 IRIX
5076a392
FC
2378
2379Conversion of strings to floating-point numbers is now more accurate on
2380IRIX systems [perl #32380].
2381
554003a2 2382=head3 Mac OS X
5076a392
FC
2383
2384Early versions of Mac OS X (Darwin) had buggy implementations of the
2385C<setregid>, C<setreuid>, C<setrgid> and C<setruid> functions, so perl
2386would pretend they did not exist.
2387
2388These functions are now recognised on Mac OS 10.5 (Leopard; Darwin 9) and
2389higher, as they have been fixed [perl #72990].
2390
554003a2 2391=head3 MirBSD
5076a392 2392
554003a2
FC
2393Previously if you built perl with a shared libperl.so on MirBSD (the
2394default config), it would work up to the installation; however, once
2395installed, it would be unable to find libperl. So path handling is now
2396treated as in the other BSD dialects.
5076a392 2397
554003a2 2398=head3 NetBSD
5076a392 2399
554003a2
FC
2400The NetBSD hints file has been changed to make the system's malloc the
2401default.
5076a392 2402
554003a2 2403=head3 Recent OpenBSDs now use perl's malloc
5076a392 2404
554003a2
FC
2405OpenBSD E<gt> 3.7 has a new malloc implementation which is mmap-based
2406and as such can release memory back to the OS; however, perl's use of
2407this malloc causes a substantial slowdown so we now default to using
2408perl's malloc instead [perl #75742].
5076a392 2409
554003a2 2410=head3 OpenVOS
5076a392 2411
554003a2 2412perl now builds again with OpenVOS (formerly known as Stratus VOS)
5a553547 2413[perl #78132] (5.12.3).
5076a392 2414
554003a2 2415=head3 Solaris
5076a392 2416
554003a2 2417DTrace is now supported on Solaris. There used to be build failures, but
5a553547 2418these have been fixed [perl #73630] (5.12.3).
5076a392 2419
554003a2 2420=head3 VMS
5076a392
FC
2421
2422=over
2423
2424=item *
2425
cdc10f43
FC
2426It's now possible to build extensions on older (pre 7.3-2) VMS systems.
2427
2428DCL symbol length was limited to 1K up until about seven years or
2429so ago, but there was no particularly deep reason to prevent those
2430older systems from configuring and building Perl (5.12.1).
2431
2432=item *
2433
2434We fixed the previously-broken C<-Uuseperlio> build on VMS.
2435
2436We were checking a variable that doesn't exist in the non-default
2437case of disabling perlio. Now we only look at it when it exists (5.12.1).
2438
2439=item *
2440
2441We fixed the -Uuseperlio command-line option in configure.com.
2442
2443Formerly it only worked if you went through all the questions
2444interactively and explicitly answered no (5.12.1).
2445
2446=item *
2447
554003a2 2448C<PerlIOUnix_open> now honours the default permissions on VMS.
5076a392 2449
554003a2
FC
2450When C<perlio> became the default and C<unixio> became the default bottom layer,
2451the most common path for creating files from Perl became C<PerlIOUnix_open>,
2452which has always explicitly used C<0666> as the permission mask.
5076a392 2453
554003a2
FC
2454To avoid this, C<0777> is now passed as the permissions to C<open()>. In the
2455VMS CRTL, C<0777> has a special meaning over and above intersecting with the
2456current umask; specifically, it allows Unix syscalls to preserve native default
5a553547
FC
2457permissions (5.12.3).
2458
2459=item *
2460
2461Spurious record boundaries are no longer
2462introduced by the PerlIO layer during output (5.12.3).
5076a392
FC
2463
2464=item *
2465
554003a2
FC
2466The shortening of symbols longer than 31 characters in the C sources is
2467now done by the compiler rather than by xsubpp (which could only do so
2468for generated symbols in XS code).
5076a392
FC
2469
2470=item *
2471
554003a2
FC
2472Record-oriented files (record format variable or variable with fixed control)
2473opened for write by the perlio layer will now be line-buffered to prevent the
2474introduction of spurious line breaks whenever the perlio buffer fills up.
5076a392 2475
d430b8e7
FC
2476=item *
2477
2478F<git_version.h> is now installed on VMS. This was an oversight in v5.12.0 which
2479caused some extensions to fail to build (5.12.2).
2480
2481=item *
2482
2483Several memory leaks in L<stat()|perlfunc/"stat FILEHANDLE"> have been fixed (5.12.2).
2484
2485=item *
2486
2487A memory leak in C<Perl_rename()> due to a double allocation has been
2488fixed (5.12.2).
2489
2490=item *
2491
2492A memory leak in C<vms_fid_to_name()> (used by C<realpath()> and
2493C<realname()>) has been fixed (5.12.2).
2494
5076a392
FC
2495=back
2496
554003a2 2497=head3 Windows
5076a392 2498
5a1f7719
FC
2499See also L</"fork() emulation will not wait for signalled children"> and
2500L</"Perl source code is read in text mode on Windows">, above.
2501
5076a392
FC
2502=over 4
2503
2504=item *
2505
554003a2 2506Fixed build process for SDK2003SP1 compilers.
5076a392 2507
554003a2 2508=item *
5076a392 2509
01b1a9e4
FC
2510Compilation with Visual Studio 2010 is now supported.
2511
2512=item *
2513
554003a2
FC
2514When using old 32-bit compilers, the define C<_USE_32BIT_TIME_T> will now
2515be set in C<$Config{ccflags}>. This improves portability when compiling
2516XS extensions using new compilers, but for a perl compiled with old 32-bit
2517compilers.
5076a392
FC
2518
2519=item *
2520
554003a2
FC
2521C<$Config{gccversion}> is now set correctly when perl is built using the
2522mingw64 compiler from L<http://mingw64.org> [perl #73754].
5076a392 2523
554003a2
FC
2524=item *
2525
d430b8e7
FC
2526When building Perl with the mingw64 x64 cross-compiler C<incpath>,
2527C<libpth>, C<ldflags>, C<lddlflags> and C<ldflags_nolargefiles> values
2528in F<Config.pm> and F<Config_heavy.pl> were not previously being set
2529correctly because, with that compiler, the include and lib directories
2530are not immediately below C<$(CCHOME)> (5.12.2).
2531
2532=item *
2533
554003a2
FC
2534The build process proceeds more smoothly with mingw and dmake when
2535F<C:\MSYS\bin> is in the PATH, due to a C<Cwd> fix.
5076a392
FC
2536
2537=item *
2538
554003a2
FC
2539Support for building with Visual C++ 2010 is now underway, but is not yet
2540complete. See F<README.win32> or L<perlwin32> for more details.
5076a392 2541
554003a2
FC
2542=item *
2543
2544The option to use an externally-supplied C<crypt()>, or to build with no
2545C<crypt()> at all, has been removed. Perl supplies its own C<crypt()>
2546implementation for Windows, and the political situation that required
2547this part of the distribution to sometimes be omitted is long gone.
5076a392
FC
2548
2549=back
2550
2551=head1 Internal Changes
2552
1e463951 2553=head2 New APIs
5076a392 2554
1e463951 2555=head3 CLONE_PARAMS structure added to ease correct thread creation
5076a392 2556
1e463951
FC
2557Modules that create threads should now create C<CLONE_PARAMS> structures
2558by calling the new function C<Perl_clone_params_new()>, and free them with
2559C<Perl_clone_params_del()>. This will ensure compatibility with any future
2560changes to the internals of the C<CLONE_PARAMS> structure layout, and that
2561it is correctly allocated and initialised.
5076a392 2562
1e463951 2563=head3 New parsing functions
5076a392 2564
1e463951
FC
2565Several functions have been added for parsing statements or multiple
2566statements:
5076a392 2567
1e463951 2568=over
5076a392
FC
2569
2570=item *
2571
1e463951 2572C<parse_fullstmt> parses a complete Perl statement.
5076a392
FC
2573
2574=item *
2575
1e463951
FC
2576C<parse_stmtseq> parses a sequence of statements, up
2577to closing brace or EOF.
5076a392
FC
2578
2579=item *
2580
1e463951 2581C<parse_block> parses a block [perl #78222].
5076a392
FC
2582
2583=item *
2584
1e463951
FC
2585C<parse_barestmt> parses a statement
2586without a label.
5076a392
FC
2587
2588=item *
2589
1e463951 2590C<parse_label> parses a statement label, separate from statements.
5076a392 2591
1e463951 2592=back
5076a392 2593
1e463951
FC
2594The
2595L<C<parse_fullexpr()>|perlapi/parse_fullexpr>,
2596L<C<parse_listexpr()>|perlapi/parse_listexpr>,
2597L<C<parse_termexpr()>|perlapi/parse_termexpr>, and
2598L<C<parse_arithexpr()>|perlapi/parse_arithexpr>
2599functions have been added to the API. They perform
2600recursive-descent parsing of expressions at various precedence levels.
2601They are expected to be used by syntax plugins.
5076a392 2602
1e463951 2603See L<perlapi> for details.
5076a392 2604
1e463951 2605=head3 Hints hash API
5076a392 2606
1e463951
FC
2607A new C API for introspecting the hinthash C<%^H> at runtime has been
2608added. See C<cop_hints_2hv>, C<cop_hints_fetchpvn>, C<cop_hints_fetchpvs>,
2609C<cop_hints_fetchsv>, and C<hv_copy_hints_hv> in L<perlapi> for details.
5076a392 2610
1e463951
FC
2611A new, experimental API has been added for accessing the internal
2612structure that Perl uses for C<%^H>. See the functions beginning with
2613C<cophh_> in L<perlapi>.
5076a392 2614
1e463951 2615=head3 C interface to C<caller()>
5076a392 2616
1e463951
FC
2617The C<caller_cx> function has been added as an XSUB-writer's equivalent of
2618C<caller()>. See L<perlapi> for details.
5076a392 2619
1e463951 2620=head3 Custom per-subroutine check hooks
5076a392 2621
1e463951
FC
2622XS code in an extension module can now annotate a subroutine (whether
2623implemented in XS or in Perl) so that nominated XS code will be called
2624at compile time (specifically as part of op checking) to change the op
2625tree of that subroutine. The compile-time check function (supplied by
2626the extension module) can implement argument processing that can't be
2627expressed as a prototype, generate customised compile-time warnings,
2628perform constant folding for a pure function, inline a subroutine
2629consisting of sufficiently simple ops, replace the whole call with a
2630custom op, and so on. This was previously all possible by hooking the
2631C<entersub> op checker, but the new mechanism makes it easy to tie the
2632hook to a specific subroutine. See L<perlapi/cv_set_call_checker>.
5076a392 2633
1e463951
FC
2634To help in writing custom check hooks, several subtasks within standard
2635C<entersub> op checking have been separated out and exposed in the API.
5076a392 2636
1e463951 2637=head3 Improved support for custom OPs
5076a392 2638
1e463951
FC
2639Custom ops can now be registered with the new C<custom_op_register> C
2640function and the C<XOP> structure. This will make it easier to add new
2641properties of custom ops in the future. Two new properties have been added
2642already, C<xop_class> and C<xop_peep>.
5076a392 2643
1e463951
FC
2644C<xop_class> is one of the OA_*OP constants, and allows L<B> and other
2645introspection mechanisms to work with custom ops
2646that aren't BASEOPs. C<xop_peep> is a pointer to
2647a function that will be called for ops of this
2648type from C<Perl_rpeep>.
5076a392 2649
1e463951
FC
2650See L<perlguts/Custom Operators> and L<perlapi/Custom Operators> for more
2651detail.
5076a392 2652
1e463951
FC
2653The old C<PL_custom_op_names>/C<PL_custom_op_descs> interface is still
2654supported but discouraged.
5076a392 2655
1e463951 2656=head3 Scope hooks
5076a392 2657
1e463951
FC
2658It is now possible for XS code to hook into Perl's lexical scope
2659mechanism at compile time, using the new C<Perl_blockhook_register>
2660function. See L<perlguts/"Compile-time scope hooks">.
5076a392 2661
1e463951 2662=head3 The recursive part of the peephole optimizer is now hookable
5076a392
FC
2663
2664In addition to C<PL_peepp>, for hooking into the toplevel peephole optimizer, a
2665C<PL_rpeepp> is now available to hook into the optimizer recursing into
2666side-chains of the optree.
2667
1e463951 2668=head3 New non-magical variants of existing functions
5076a392 2669
1e463951
FC
2670The following functions/macros have been added to the API. The C<*_nomg>
2671macros are equivalent to their non-_nomg variants, except that they ignore
2672get-magic. Those ending in C<_flags> allow one to specify whether
2673get-magic is processed.
5076a392 2674
1e463951
FC
2675 sv_2bool_flags
2676 SvTRUE_nomg
2677 sv_2nv_flags
2678 SvNV_nomg
2679 sv_cmp_flags
2680 sv_cmp_locale_flags
2681 sv_eq_flags
2682 sv_collxfrm_flags
5076a392 2683
1e463951 2684In some of these cases, the non-_flags functions have
5076a392
FC
2685been replaced with wrappers around the new functions.
2686
1e463951 2687=head3 pv/pvs/sv versions of existing functions
5076a392 2688
1e463951 2689Many functions ending with pvn now have equivalent pv/pvs/sv versions.
5076a392 2690
1e463951 2691=head3 List op-building functions
5076a392 2692
1e463951
FC
2693List op-building functions have been added to the
2694API. See L<op_append_elem|perlapi/op_append_elem>,
2695L<op_append_list|perlapi/op_append_list>, and
2696L<op_prepend_elem|perlapi/op_prepend_elem> in L<perlapi>.
5076a392 2697
1e463951 2698=head3 C<LINKLIST>
5076a392 2699
1e463951
FC
2700The L<LINKLIST|perlapi/LINKLIST> macro, part of op building that
2701constructs the execution-order op chain, has been added to the API.
5076a392 2702
1e463951 2703=head3 Localisation functions
5076a392 2704
1e463951
FC
2705The C<save_freeop>, C<save_op>, C<save_pushi32ptr> and C<save_pushptrptr>
2706functions have been added to the API.
5076a392 2707
1e463951 2708=head3 Stash names
5076a392 2709
1e463951
FC
2710A stash can now have a list of effective names in addition to its usual
2711name. The first effective name can be accessed via the C<HvENAME> macro,
2712which is now the recommended name to use in MRO linearisations (C<HvNAME>
2713being a fallback if there is no C<HvENAME>).
5076a392 2714
1e463951
FC
2715These names are added and deleted via C<hv_ename_add> and
2716C<hv_ename_delete>. These two functions are I<not> part of the API.
5076a392 2717
1e463951 2718=head3 New functions for finding and removing magic
5076a392 2719
1e463951
FC
2720The L<C<mg_findext()>|perlapi/mg_findext> and
2721L<C<sv_unmagicext()>|perlapi/sv_unmagicext>
2722functions have been added to the API.
2723They allow extension authors to find and remove magic attached to
2724scalars based on both the magic type and the magic virtual table, similar to how
2725C<sv_magicext()> attaches magic of a certain type and with a given virtual table
2726to a scalar. This eliminates the need for extensions to walk the list of
2727C<MAGIC> pointers of an C<SV> to find the magic that belongs to them.
5076a392 2728
1e463951 2729=head3 C<find_rundefsv>
5076a392 2730
1e463951
FC
2731This function returns the SV representing C<$_>, whether it's lexical
2732or dynamic.
5076a392 2733
1e463951 2734=head3 C<Perl_croak_no_modify>
5076a392 2735
1e463951
FC
2736C<Perl_croak_no_modify()> is short-hand for
2737C<Perl_croak("%s", PL_no_modify)>.
5076a392 2738
1e463951 2739=head3 C<PERL_STATIC_INLINE> define
5076a392 2740
1e463951
FC
2741The C<PERL_STATIC_INLINE> define has been added to provide the best-guess
2742incantation to use for static inline functions, if the C compiler supports
2743C99-style static inline. If it doesn't, it'll give a plain C<static>.
5076a392 2744
1e463951
FC
2745C<HAS_STATIC_INLINE> can be used to check if the compiler actually supports
2746inline functions.
5076a392 2747
1e463951 2748=head3 New C<pv_escape> option for hexadecimal escapes
5076a392 2749
1e463951
FC
2750A new option, C<PERL_PV_ESCAPE_NONASCII>, has been added to C<pv_escape> to
2751dump all characters above ASCII in hexadecimal. Before, one could get all
2752characters as hexadecimal or the Latin1 non-ASCII as octal.
5076a392 2753
1e463951 2754=head3 C<lex_start>
5076a392 2755
1e463951 2756C<lex_start> has been added to the API, but is considered experimental.
5076a392 2757
1e463951 2758=head3 C<op_scope()> and C<op_lvalue()>
5076a392 2759
1e463951
FC
2760The C<op_scope()> and C<op_lvalue()> functions have been added to the API,
2761but are considered experimental.
5076a392 2762
1e463951 2763=head2 C API Changes
5076a392 2764
1e463951 2765=head3 C<PERL_POLLUTE> has been removed
5076a392 2766
1e463951
FC
2767The option to define C<PERL_POLLUTE> to expose older 5.005 symbols for
2768backwards compatibility has been removed. It's use was always discouraged,
2769and MakeMaker contains a more specific escape hatch:
5076a392 2770
1e463951 2771 perl Makefile.PL POLLUTE=1
5076a392 2772
1e463951
FC
2773This can be used for modules that have not been upgraded to 5.6 naming
2774conventions (and really should be completely obsolete by now).
5076a392 2775
1e463951 2776=head3 Check API compatibility when loading XS modules
5076a392 2777
1e463951
FC
2778When perl's API changes in incompatible ways (which usually happens between
2779major releases), XS modules compiled for previous versions of perl will not
2780work anymore. They will need to be recompiled against the new perl.
5076a392 2781
1e463951
FC
2782In order to ensure that modules are recompiled, and to prevent users from
2783accidentally loading modules compiled for old perls into newer ones, the
2784C<XS_APIVERSION_BOOTCHECK> macro has been added. That macro, which is
2785called when loading every newly compiled extension, compares the API
2786version of the running perl with the version a module has been compiled for
2787and raises an exception if they don't match.
5076a392 2788
1e463951 2789=head3 Perl_fetch_cop_label
5076a392 2790
1e463951
FC
2791The first argument of the C API function C<Perl_fetch_cop_label> has changed
2792from C<struct refcounted he *> to C<COP *>, to insulate the user from
2793implementation details.
5076a392 2794
1e463951
FC
2795This API function was marked as "may change", and likely isn't in use outside
2796the core. (Neither an unpacked CPAN, nor Google's codesearch, finds any other
2797references to it.)
5076a392 2798
1e463951 2799=head3 GvCV() and GvGP() are no longer lvalues
5076a392 2800
1e463951
FC
2801The new GvCV_set() and GvGP_set() macros are now provided to replace
2802assignment to those two macros.
5076a392 2803
1e463951
FC
2804This allows a future commit to eliminate some backref magic between GV
2805and CVs, which will require complete control over assignment to the
2806gp_cv slot.
5076a392 2807
1e463951 2808=head3 CvGV() is no longer an lvalue
5076a392 2809
1e463951
FC
2810Under some circumstances, the C<CvGV()> field of a CV is now
2811reference-counted. To ensure consistent behaviour, direct assignment to
2812it, for example C<CvGV(cv) = gv> is now a compile-time error. A new macro,
2813C<CvGV_set(cv,gv)> has been introduced to perform this operation
2814safely. Note that modification of this field is not part of the public
2815API, regardless of this new macro (and despite its being listed in this section).
5076a392 2816
1e463951 2817=head3 CvSTASH() is no longer an lvalue
5076a392 2818
1e463951
FC
2819The C<CvSTASH()> macro can now only be used as an rvalue. C<CvSTASH_set()>
2820has been added to replace assignment to C<CvSTASH()>. This is to ensure
2821that backreferences are handled properly. These macros are not part of the
2822API.
5076a392 2823
1e463951 2824=head3 Calling conventions for C<newFOROP> and C<newWHILEOP>
5076a392 2825
1e463951
FC
2826The way the parser handles labels has been cleaned up and refactored. As a
2827result, the C<newFOROP()> constructor function no longer takes a parameter
2828stating what label is to go in the state op.
5076a392 2829
1e463951
FC
2830The C<newWHILEOP()> and C<newFOROP()> functions no longer accept a line
2831number as a parameter.
5076a392 2832
1e463951 2833=head3 Flags passed to C<uvuni_to_utf8_flags> and C<utf8n_to_uvuni>
5076a392 2834
1e463951
FC
2835Some of the flags parameters to uvuni_to_utf8_flags() and
2836utf8n_to_uvuni() have changed. This is a result of Perl's now allowing
5076a392
FC
2837internal storage and manipulation of code points that are problematic
2838in some situations. Hence, the default actions for these functions has
2839been complemented to allow these code points. The new flags are
2840documented in L<perlapi>. Code that requires the problematic code
483b16f3 2841points to be rejected needs to change to use the new flags. Some flag
5076a392
FC
2842names are retained for backward source compatibility, though they do
2843nothing, as they are now the default. However the flags
2844C<UNICODE_ALLOW_FDD0>, C<UNICODE_ALLOW_FFFF>, C<UNICODE_ILLEGAL>, and
2845C<UNICODE_IS_ILLEGAL> have been removed, as they stem from a
2846fundamentally broken model of how the Unicode non-character code points
2847should be handled, which is now described in
2848L<perlunicode/Non-character code points>. See also L</Selected Bug Fixes>.
2849
1e463951 2850XXX Which bugs in particular? Selected Bug Fixes is too long for this link
483b16f3
KW
2851to be meaningful right now
2852I don't see the bugs in that section currently -- khw
5076a392 2853
1e463951 2854=head2 Deprecated C APIs
5076a392 2855
1e463951 2856=over
5076a392 2857
1e463951 2858=item C<Perl_ptr_table_clear>
5076a392 2859
1e463951
FC
2860C<Perl_ptr_table_clear> is no longer part of Perl's public API. Calling it
2861now generates a deprecation warning, and it will be removed in a future
2862release.
5076a392 2863
1e463951 2864=item C<sv_compile_2op>
5076a392 2865
1e463951
FC
2866The C<sv_compile_2op()> API function is now deprecated. Searches suggest
2867that nothing on CPAN is using it, so this should have zero impact.
5076a392 2868
1e463951
FC
2869It attempted to provide an API to compile code down to an optree, but failed
2870to bind correctly to lexicals in the enclosing scope. It's not possible to
2871fix this problem within the constraints of its parameters and return value.
5076a392 2872
1e463951 2873=item C<find_rundefsvoffset>
5076a392 2874
1e463951
FC
2875The C<find_rundefsvoffset> function has been deprecated. It appeared that
2876its design was insufficient for reliably getting the lexical C<$_> at
2877run-time.
5076a392 2878
1e463951
FC
2879Use the new C<find_rundefsv> function or the C<UNDERBAR> macro
2880instead. They directly return the right SV representing C<$_>, whether it's
2881lexical or dynamic.
5076a392 2882
1e463951 2883=item C<CALL_FPTR> and C<CPERLscope>
5076a392 2884
1e463951
FC
2885Those are left from an old implementation of C<MULTIPLICITY> using C++ objects,
2886which was removed in Perl 5.8. Nowadays these macros do exactly nothing, so
2887they shouldn't be used anymore.
5076a392 2888
1e463951
FC
2889For compatibility, they are still defined for external C<XS> code. Only
2890extensions defining C<PERL_CORE> must be updated now.
5076a392 2891
1e463951 2892=back
5076a392 2893
1e463951 2894=head2 Other Internal Changes
5076a392 2895
1e463951 2896=head3 Stack unwinding
5076a392 2897
1e463951
FC
2898The protocol for unwinding the C stack at the last stage of a C<die>
2899has changed how it identifies the target stack frame. This now uses
2900a separate variable C<PL_restartjmpenv>, where previously it relied on
2901the C<blk_eval.cur_top_env> pointer in the C<eval> context frame that
2902has nominally just been discarded. This change means that code running
2903during various stages of Perl-level unwinding no longer needs to take
2904care to avoid destroying the ghost frame.
5076a392 2905
1e463951 2906=head3 Scope stack entries
5076a392 2907
1e463951
FC
2908The format of entries on the scope stack has been changed, resulting in a
2909reduction of memory usage of about 10%. In particular, the memory used by
2910the scope stack to record each active lexical variable has been halved.
5076a392 2911
1e463951 2912=head3 Memory allocation for pointer tables
5076a392 2913
1e463951
FC
2914Memory allocation for pointer tables has been changed. Previously
2915C<Perl_ptr_table_store> allocated memory from the same arena system as
2916C<SV> bodies and C<HE>s, with freed memory remaining bound to those arenas
2917until interpreter exit. Now it allocates memory from arenas private to the
2918specific pointer table, and that memory is returned to the system when
2919C<Perl_ptr_table_free> is called. Additionally, allocation and release are
2920both less CPU intensive.
5076a392 2921
1e463951 2922=head3 C<UNDERBAR>
5076a392 2923
1e463951
FC
2924The C<UNDERBAR> macro now calls C<find_rundefsv>. C<dUNDERBAR> is now a
2925noop but should still be used to ensure past and future compatibility.
5076a392 2926
1e463951 2927=head3 String comparison routines renamed
5076a392 2928
1e463951
FC
2929The ibcmp_* functions have been renamed and are now called foldEQ,
2930foldEQ_locale and foldEQ_utf8. The old names are still available as
2931macros.
2932
2933=head3 C<chop> and C<chomp> implementations merged
2934
2935The opcode bodies for C<chop> and C<chomp> and for C<schop> and C<schomp>
2936have been merged. The implementation functions C<Perl_do_chop()> and
2937C<Perl_do_chomp()>, never part of the public API, have been merged and
2938moved to a static function in F<pp.c>. This shrinks the perl binary
2939slightly, and should not affect any code outside the core (unless it is
2940relying on the order of side effects when C<chomp> is passed a I<list> of
2941values).
5076a392
FC
2942
2943=head1 Selected Bug Fixes
2944
e8e35311
FC
2945=head2 I/O
2946
5076a392
FC
2947=over 4
2948
2949=item *
2950
e8e35311 2951Perl no longer produces this warning:
a593b319
FC
2952
2953 $ perl -we 'open my $f, ">", \my $x; binmode $f, "scalar"'
2954 Use of uninitialized value in binmode at -e line 1.
2955
2956=item *
2957
e8e35311
FC
2958Opening a glob reference via C<< open $fh, "E<gt>", \*glob >> will no longer
2959cause the glob to be corrupted when the filehandle is printed to. This would
2960cause perl to crash whenever the glob's contents were accessed
2961[perl #77492].
4ed2cea4
FC
2962
2963=item *
2964
e8e35311
FC
2965PerlIO no longer crashes when called recursively, e.g., from a signal
2966handler. Now it just leaks memory [perl #75556].
4ed2cea4
FC
2967
2968=item *
2969
e8e35311
FC
2970Most I/O functions were not warning for unopened handles unless the
2971'closed' and 'unopened' warnings categories were both enabled. Now only
2972C<use warnings 'unopened'> is necessary to trigger these warnings (as was
438c239f 2973always meant to be the case).
4ed2cea4
FC
2974
2975=item *
2976
438c239f 2977There have been several fixes to PerlIO layers:
e8e35311 2978
438c239f
FC
2979When C<binmode FH, ":crlf"> pushes the C<:crlf> layer on top of the stack,
2980it no longer enables crlf layers lower in the stack, to avoid unexpected
2981results [perl #38456].
4ed2cea4 2982
438c239f
FC
2983Opening a file in C<:raw> mode now does what it advertises to do (first
2984open the file, then binmode it), instead of simply leaving off the top
2985layer [perl #80764].
5076a392 2986
438c239f
FC
2987The three layers C<:pop>, C<:utf8> and C<:bytes> didn't allow stacking when
2988opening a file. For example
e8e35311 2989this:
5076a392 2990
e8e35311 2991 open FH, '>:pop:perlio', 'some.file' or die $!;
5076a392 2992
438c239f
FC
2993Would throw an error: "Invalid argument". This has been fixed in this
2994release [perl #82484].
5076a392 2995
e8e35311
FC
2996=back
2997
2998=head2 Regular Expression Bug Fixes
2999
3000=over
5076a392
FC
3001
3002=item *
3003
e8e35311
FC
3004The regular expression engine no longer loops when matching
3005C<"\N{LATIN SMALL LIGATURE FF}" =~ /f+/i> and similar expressions
cdc10f43 3006[perl #72998] (5.12.1).
5076a392
FC
3007
3008=item *
3009
e8e35311
FC
3010The trie runtime code should no longer allocate massive amounts of memory,
3011fixing #74484.
5076a392
FC
3012
3013=item *
3014
438c239f
FC
3015Syntax errors in C<< (?{...}) >> blocks no longer cause panic messages
3016[perl #2353].
5076a392
FC
3017
3018=item *
3019
438c239f
FC
3020A pattern like C<(?:(o){2})?> no longer causes a "panic" error
3021[perl #39233].
5076a392
FC
3022
3023=item *
3024
438c239f 3025A fatal error in regular expressions containing C<(.*?)> when processing
d430b8e7 3026UTF-8 data has been fixed [perl #75680] (5.12.2).
5076a392
FC
3027
3028=item *
3029
e8e35311 3030An erroneous regular expression engine optimisation that caused regex verbs like
438c239f 3031C<*COMMIT> sometimes to be ignored has been removed.
5076a392
FC
3032
3033=item *
3034
e8e35311
FC
3035The regular expression bracketed character class C<[\8\9]> was effectively the
3036same as C<[89\000]>, incorrectly matching a NULL character. It also gave
3037incorrect warnings that the C<8> and C<9> were ignored. Now C<[\8\9]> is the
3038same as C<[89]> and gives legitimate warnings that C<\8> and C<\9> are
3039unrecognized escape sequences, passed-through.
5076a392
FC
3040
3041=item *
3042
e8e35311
FC
3043A regular expression match in the right-hand side of a global substitution
3044(C<s///g>) that is in the same scope will no longer cause match variables
3045to have the wrong values on subsequent iterations. This can happen when an
3046array or hash subscript is interpolated in the right-hand side, as in
3047C<s|(.)|@a{ print($1), /./ }|g> [perl #19078].
5076a392
FC
3048
3049=item *
3050
438c239f
FC
3051Several cases in which characters in the Latin-1 non-ASCII range (0x80 to
30520xFF) used not to match themselves or used to match both a character class
3053and its complement have been fixed. For instance, U+00E2 could match both
3054C<\w> and C<\W> [perl #78464] [perl #18281] [perl #60156].
5076a392
FC
3055
3056=item *
3057
e8e35311
FC
3058Matching a Unicode character against an alternation containing characters
3059that happened to match continuation bytes in the former's UTF8
3060representation (C<qq{\x{30ab}} =~ /\xab|\xa9/>) would cause erroneous
3061warnings [perl #70998].
5076a392
FC
3062
3063=item *
3064
e8e35311
FC
3065The trie optimisation was not taking empty groups into account, preventing
3066'foo' from matching C</\A(?:(?:)foo|bar|zot)\z/> [perl #78356].
5076a392
FC
3067
3068=item *
3069
e8e35311
FC
3070A pattern containing a C<+> inside a lookahead would sometimes cause an
3071incorrect match failure in a global match (e.g., C</(?=(\S+))/g>)
3072[perl #68564].
5076a392
FC
3073
3074=item *
3075
e8e35311
FC
3076A regular expression optimisation would sometimes cause a match with a
3077C<{n,m}> quantifier to fail when it should match [perl #79152].
5076a392
FC
3078
3079=item *
3080
e8e35311 3081Case insensitive matching in regular expressions compiled under C<use
438c239f
FC
3082locale> now works much more sanely when the pattern or
3083target string is encoded internally in
3084UTF8. Previously, under these conditions the localeness
e8e35311
FC
3085was completely lost. Now, code points above 255 are treated as Unicode,
3086but code points between 0 and 255 are treated using the current locale
438c239f
FC
3087rules, regardless of whether the pattern or the string is encoded in UTF8.
3088The few case-insensitive matches that cross the 255/256 boundary are not
e8e35311
FC
3089allowed. For example, 0xFF does not caselessly match the character at
30900x178, LATIN CAPITAL LETTER Y WITH DIAERESIS, because 0xFF may not be
3091LATIN SMALL LETTER Y in the current locale, and Perl has no way of
3092knowing if that character even exists in the locale, much less what code
3093point it is.
5076a392
FC
3094
3095=item *
3096
e8e35311
FC
3097The C<(?|...)> regular expression construct no longer crashes if the final
3098branch has more sets of capturing parentheses than any other branch. This
3099was fixed in Perl 5.10.1 for the case of a single branch, but that fix did
3100not take multiple branches into account [perl #84746].
5076a392
FC
3101
3102=item *
3103
e8e35311
FC
3104A bug has been fixed in the implementation of C<{...}> quantifiers in
3105regular expressions that prevented the code block in
3106C</((\w+)(?{ print $2 })){2}/> from seeing the C<$2> sometimes
3107[perl #84294].
5076a392 3108
e8e35311 3109=back
5076a392 3110
e8e35311
FC
3111=head2 Syntax/Parsing Bugs
3112
3113=over
5076a392
FC
3114
3115=item *
3116
e8e35311 3117C<when(scalar){...}> no longer crashes, but produces a syntax error
cdc10f43 3118[perl #74114] (5.12.1).
5076a392
FC
3119
3120=item *
3121
e8e35311
FC
3122A label right before a string eval (C<foo: eval $string>) no longer causes
3123the label to be associated also with the first statement inside the eval
3124[perl #74290] (5.12.1).
5076a392
FC
3125
3126=item *
3127
b2c076b5 3128The C<no 5.13.2;> form of C<no> no longer tries to turn on features or
d430b8e7 3129pragmata (i.e., strict) [perl #70075] (5.12.2).
5076a392
FC
3130
3131=item *
3132
b2c076b5
FC
3133C<BEGIN {require 5.12.0}> now behaves as documented, rather than behaving
3134identically to C<use 5.12.0;>. Previously, C<require> in a C<BEGIN> block
3135was erroneously executing the C<use feature ':5.12.0'> and
3136C<use strict;> behaviour, which only C<use> was documented to
3137provide [perl #69050].
5076a392
FC
3138
3139=item *
3140
5076a392
FC
3141A regression introduced in Perl 5.12.0, making
3142C<< my $x = 3; $x = length(undef) >> result in C<$x> set to C<3> has been
d430b8e7 3143fixed. C<$x> will now be C<undef> [perl #85508] (5.12.2).
b2c076b5
FC
3144
3145=item *
3146
3147When strict 'refs' mode is off, C<%{...}> in rvalue context returns
3148C<undef> if its argument is undefined. An optimisation introduced in perl
31495.12.0 to make C<keys %{...}> faster when used as a boolean did not take
3150this into account, causing C<keys %{+undef}> (and C<keys %$foo> when
3151C<$foo> is undefined) to be an error, which it should only be in strict
3152mode [perl #81750].
5076a392
FC
3153
3154=item *
3155
e8e35311 3156Constant-folding used to cause
5076a392 3157
e8e35311 3158 $text =~ ( 1 ? /phoo/ : /bear/)
5076a392 3159
e8e35311
FC
3160to turn into
3161
3162 $text =~ /phoo/
3163
3164at compile time. Now it correctly matches against C<$_> [perl #20444].
5076a392
FC
3165
3166=item *
3167
e8e35311
FC
3168Parsing Perl code (either with string C<eval> or by loading modules) from
3169within a C<UNITCHECK> block no longer causes the interpreter to crash
3170[perl #70614].
5076a392
FC
3171
3172=item *
3173
b2c076b5
FC
3174String evals no longer fail after 2 billion scopes have been
3175compiled [perl #83364].
3176
3177=item *
3178
e8e35311
FC
3179The parser no longer hangs when encountering certain Unicode characters,
3180such as U+387 [perl #74022].
5076a392
FC
3181
3182=item *
3183
b2c076b5
FC
3184Several contexts no longer allow a Unicode character to begin a word
3185that should never begin words, for an example an accent that must follow
3186another character previously could precede all other characters.
5076a392
FC
3187
3188=item *
3189
e8e35311
FC
3190Defining a constant with the same name as one of perl's special blocks
3191(e.g., INIT) stopped working in 5.12.0, but has now been fixed
3192[perl #78634].
5076a392
FC
3193
3194=item *
3195
e8e35311
FC
3196A reference to a literal value used as a hash key (C<$hash{\"foo"}>) used
3197to be stringified, even if the hash was tied [perl #79178].
5076a392
FC
3198
3199=item *
3200
e8e35311
FC
3201A closure containing an C<if> statement followed by a constant or variable
3202is no longer treated as a constant [perl #63540].
5076a392
FC
3203
3204=item *
3205
e8e35311
FC
3206C<state> can now be used with attributes. It used to mean the same thing as
3207C<my> if attributes were present [perl #68658].
5076a392
FC
3208
3209=item *
3210
e8e35311
FC
3211Expressions like C<< @$a > 3 >> no longer cause C<$a> to be mentioned in
3212the "Use of uninitialized value in numeric gt" warning when C<$a> is
3213undefined (since it is not part of the C<E<gt>> expression, but the operand
3214of the C<@>) [perl #72090].
5076a392
FC
3215
3216=item *
3217
e8e35311
FC
3218Accessing an element of a package array with a hard-coded number (as
3219opposed to an arbitrary expression) would crash if the array did not exist.
3220Usually the array would be autovivified during compilation, but typeglob
3221manipulation could remove it, as in these two cases which used to crash:
5076a392 3222
e8e35311
FC
3223 *d = *a; print $d[0];
3224 undef *d; print $d[0];
5076a392 3225
2c389f6c
FC
3226=item *
3227
3228The C<-C> command line option, when used on the shebang line, can now be
3229followed by other options [perl #72434].
3230
3231=item *
3232
3233The C<B> module was returning C<B::OP>s instead of C<B::LOGOP>s for C<entertry> [perl #80622].
3234This was due to a bug in the perl core, not in C<B> itself.
3235
e8e35311 3236=back
5076a392 3237
e262cb24
FC
3238=head2 Stashes, Globs and Method Lookup
3239
3240Perl 5.10.0 introduced a new internal mechanism for caching MROs (method
3241resolution orders, or lists of parent classes; aka "isa" caches) to make
3242method lookup faster (so @ISA arrays would not have to be searched
3243repeatedly). Unfortunately, this brought with it quite a few bugs. Almost
3244all of these have been fixed now, along with a few MRO-related bugs that
3245existed before 5.10.0:
3246
3247=over
3248
3249=item *
3250
3251The following used to have erratic effects on method resolution, because
3252the "isa" caches were not reset or otherwise ended up listing the wrong
3253classes. These have been fixed.
3254
3255=over
3256
3257=item Aliasing packages by assigning to globs [perl #77358]
3258
3259=item Deleting packages by deleting their containing stash elements
3260
3261=item Undefining the glob containing a package (C<undef *Foo::>)
3262
3263=item Undefining an ISA glob (C<undef *Foo::ISA>)
3264
3265=item Deleting an ISA stash element (C<delete $Foo::{ISA}>)
3266
3267=item Sharing @ISA arrays between classes (via C<*Foo::ISA = \@Bar::ISA> or
3268C<*Foo::ISA = *Bar::ISA>) [perl #77238]
3269
3270=back
3271
3272C<undef *Foo::ISA> would even stop a new C<@Foo::ISA> array from updating
3273caches.
3274
3275=item *
3276
3277Typeglob assignments would crash if the glob's stash no longer existed, so
3278long as the glob assigned to was named 'ISA' or the glob on either side of
3279the assignment contained a subroutine.
3280
3281=item *
3282
3283C<PL_isarev>, which is accessible to Perl via C<mro::get_isarev> is now
3284updated properly when packages are deleted or removed from the C<@ISA> of
3285other classes. This allows many packages to be created and deleted without
3286causing a memory leak [perl #75176].
3287
3288=back
3289
3290In addition, various other bugs related to typeglobs and stashes have been
3291fixed:
5076a392 3292
e8e35311 3293=over
5076a392
FC
3294
3295=item *
3296
e8e35311 3297Some work has been done on the internal pointers that link between symbol
e262cb24 3298tables (stashes), typeglobs and subroutines. This has the effect that
e8e35311
FC
3299various edge cases related to deleting stashes or stash entries (e.g.
3300<%FOO:: = ()>), and complex typeglob or code reference aliasing, will no
3301longer crash the interpreter.
5076a392
FC
3302
3303=item *
3304
e262cb24
FC
3305Assigning a reference to a glob copy now assigns to a glob slot instead of
3306overwriting the glob with a scalar [perl #1804] [perl #77508].
5076a392
FC
3307
3308=item *
3309
e8e35311
FC
3310A bug when replacing the glob of a loop variable within the loop has been fixed
3311[perl #21469]. This
3312means the following code will no longer crash:
5076a392 3313
e8e35311
FC
3314 for $x (...) {
3315 *x = *y;
3316 }
5076a392
FC
3317
3318=item *
3319
3320Assigning a glob to a PVLV used to convert it to a plain string. Now it
3321works correctly, and a PVLV can hold a glob. This would happen when a
3322nonexistent hash or array element was passed to a subroutine:
3323
3324 sub { $_[0] = *foo }->($hash{key});
3325 # $_[0] would have been the string "*main::foo"
3326
3327It also happened when a glob was assigned to, or returned from, an element
3328of a tied array or hash [perl #36051].
3329
3330=item *
44691e6f 3331
e8e35311 3332When trying to report C<Use of uninitialized value $Foo::BAR>, crashes could
e262cb24
FC
3333occur if the glob holding the global variable in question had been detached
3334from its original stash by, for example, C<delete $::{'Foo::'}>. This has
3335been fixed by disabling the reporting of variable names in those
e8e35311 3336cases.
44691e6f
AB
3337
3338=item *
3339
e8e35311
FC
3340During the restoration of a localised typeglob on scope exit, any
3341destructors called as a result would be able to see the typeglob in an
3342inconsistent state, containing freed entries, which could result in a
3343crash. This would affect code like this:
3344
3345 local *@;
3346 eval { die bless [] }; # puts an object in $@
3347 sub DESTROY {
3348 local $@; # boom
3349 }
3350
3351Now the glob entries are cleared before any destructors are called. This
3352also means that destructors can vivify entries in the glob. So perl tries
3353again and, if the entries are re-created too many times, dies with a
3354'panic: gp_free...' error message.
3355
3356=back
3357
3358=head2 Unicode
3359
3360=over
44691e6f 3361
5076a392 3362=item *
44691e6f 3363
e8e35311
FC
3364What has become known as the "Unicode Bug" is mostly resolved in this release.
3365Under C<use feature 'unicode_strings'>, the internal storage format of a
3366string no longer affects the external semantics. There are two known
3367exceptions. User-defined case changing functions, which are planned to
3368be deprecated in 5.14, require utf8-encoded strings to function; and the
3369character C<LATIN SMALL LETTER SHARP S> in regular expression
3370case-insensitive matching has a somewhat different set of bugs depending
3371on the internal storage format. Case-insensitive matching of all
3372characters that have multi-character matches, as this one does, is
3373problematical in Perl [perl #58182].
911a3729 3374
5076a392 3375=item *
c8c13991 3376
e8e35311
FC
3377The handling of Unicode non-characters has changed.
3378Previously they were mostly considered illegal, except that only one of
3379the 66 of them was known about in places. The Unicode standard
3380considers them legal, but forbids the "open interchange" of them.
3381This is part of the change to allow the internal use of any code point
3382(see L</Core Enhancements>). Together, these changes resolve
9a5a48b7
FC
3383[perl #38722], [perl #51918], [perl #51936], [perl #63446].
3384
3385=item *
3386
3387Naming a deprecated character in \N{...} no longer leaks memory.
3388
3389=item *
3390
cdc10f43
FC
3391We fixed a bug that could cause \N{} constructs followed by a single . to
3392be parsed incorrectly [perl #74978] (5.12.1).
3393
3394=item *
3395
9a5a48b7
FC
3396C<chop> now correctly handles characters above "\x{7fffffff}"
3397[perl #73246].
3398
3399=item *
3400
3401Passing to C<index> an offset beyond the end of the string when the string
3402is encoded internally in UTF8 no longer causes panics [perl #75898].
3403
3404=item *
3405
3406C<warn()> and C<die()> now respect utf8-encoded scalars [perl #45549].
c8c13991 3407
5076a392
FC
3408=item *
3409
9a5a48b7 3410Sometimes the UTF8 length cache would not be reset on a value
e8e35311 3411returned by substr, causing C<length(substr($uni_string,...))> to give
9a5a48b7
FC
3412wrong answers. With C<${^UTF8CACHE}> set to -1, it would produce a 'panic'
3413error message, too [perl #77692].
e8e35311
FC
3414
3415=back
3416
e9784f55 3417=head2 Ties, Overloading and Other Magic
e8e35311
FC
3418
3419=over
35cdccfc 3420
5076a392
FC
3421=item *
3422
e8e35311 3423Overloading now works properly in conjunction with tied
e9784f55 3424variables. What formerly happened was that most ops checked their
e8e35311
FC
3425arguments for overloading I<before> checking for magic, so for example
3426an overloaded object returned by a tied array access would usually be
e9784f55 3427treated as not overloaded [RT #57012].
911a3729 3428
5076a392 3429=item *
58f55cb3 3430
e9784f55
FC
3431Various cases of magic (e.g., tie methods) being called on tied variables
3432too many or too few times have been fixed:
3433
3434=over
58f55cb3 3435
5076a392 3436=item *
6b3df227 3437
e9784f55 3438FETCH is no longer called on tied variables in void context.
6b3df227 3439
5076a392 3440=item *
c9989a74 3441
e9784f55 3442C<$tied-E<gt>()> did not always call FETCH [perl #8438].
c9989a74 3443
5076a392
FC
3444=item *
3445
e9784f55
FC
3446Filetest operators and C<y///> and C<tr///> were calling FETCH too
3447many times.
b7188eb5
FC
3448
3449=item *
3450
e9784f55
FC
3451The C<=> operator used to ignore magic on its right-hand side if the
3452scalar happened to hold a typeglob (if a typeglob was the last thing
3453returned from or assigned to a tied scalar) [perl #77498].
911a3729 3454
5076a392 3455=item *
c8c13991 3456
e9784f55
FC
3457Dereference operators used to ignore magic if the argument was a
3458reference already (e.g., from a previous FETCH) [perl #72144].
c8c13991 3459
e8e35311 3460=item *
f00d3350 3461
e9784f55
FC
3462C<splice> now calls set-magic (so changes made
3463by C<splice @ISA> are respected by method calls) [perl #78400].
3464
d430b8e7
FC
3465=item *
3466
3467In-memory files created by C<open $fh, 'E<gt>' \$buffer> were not calling
3468FETCH/STORE at all [perl #43789] (5.12.2).
3469
e9784f55 3470=back
c34a735e 3471
5076a392 3472=item *
b7188eb5 3473
e9784f55
FC
3474String C<eval> now detects taintedness of overloaded or tied
3475arguments [perl #75716].
b7188eb5 3476
5076a392 3477=item *
b7188eb5 3478
e9784f55
FC
3479String C<eval> and regular expression matches against objects with string
3480overloading no longer cause memory corruption or crashes [perl 77084].
c34a735e 3481
05dbc6f8
KW
3482=item *
3483
e9784f55
FC
3484L<readline|perlfunc/"readline EXPR"> now honors C<< <> >> overloading on tied
3485arguments.
7b98b857 3486
5076a392 3487=item *
05dbc6f8 3488
e9784f55
FC
3489C<< E<lt>exprE<gt> >> always respects overloading now if the expression is
3490overloaded.
3491
3492Due to the way that 'E<lt>E<gt> as glob' was parsed differently from
3493'E<lt>E<gt> as filehandle' from 5.6 onwards, something like C<< E<lt>$foo[0]E<gt> >> did
3494not handle overloading, even if C<$foo[0]> was an overloaded object. This
3495was contrary to the documentation for overload, and meant that C<< E<lt>E<gt> >>
3496could not be used as a general overloaded iterator operator.
05dbc6f8
KW
3497
3498=item *
3499
e8e35311
FC
3500The fallback behaviour of overloading on binary operators was asymmetric
3501[perl #71286].
05dbc6f8 3502
5076a392 3503=item *
05dbc6f8 3504
e9784f55
FC
3505Magic applied to variables in the main package no longer affects other packages.
3506See L</Magic variables outside the main package> above [perl #76138].
05dbc6f8 3507
5076a392 3508=item *
05dbc6f8 3509
e9784f55
FC
3510Sometimes magic (ties, taintedness, etc.) attached to variables could cause
3511an object to last longer than it should, or cause a crash if a tied
3512variable were freed from within a tie method. These have been fixed
3513[perl #81230].
05dbc6f8
KW
3514
3515=item *
3516
e8e35311
FC
3517DESTROY methods of objects implementing ties are no longer able to crash by
3518accessing the tied variable through a weak reference [perl #86328].
3519
2c389f6c
FC
3520=item *
3521
3522Fixed a regression of kill() when a match variable is used for the
3523process ID to kill [perl #75812].
3524
3525=item *
3526
3527C<$AUTOLOAD> used to remain tainted forever if it ever became tainted. Now
3528it is correctly untainted if an autoloaded method is called and the method
3529name was not tainted.
3530
3531=item *
3532
3533C<sprintf> now dies when passed a tainted scalar for the format. It did
3534already die for arbitrary expressions, but not for simple scalars
3535[perl #82250].
3536
cdc10f43
FC
3537=item *
3538
3539utf8::is_utf8 now respects get-magic (e.g. $1) (5.12.1).
3540
e8e35311
FC
3541=back
3542
3543=head2 The Debugger
3544
3545=over
05dbc6f8 3546
5076a392 3547=item *
05dbc6f8 3548
bdb0cce8 3549The Perl debugger now also works in taint mode [perl #76872].
4d56cd4f 3550
5076a392
FC
3551=item *
3552
bdb0cce8 3553Subroutine redefinition works once more in the debugger [perl #48332].
05dbc6f8 3554
911a3729
FC