[perl5.git] / pod / perl5201delta.pod

=encoding utf8

=head1 NAME

perl5201delta - what is new for perl v5.20.1

=head1 DESCRIPTION

This document describes differences between the 5.20.0 release and the 5.20.1
release.

If you are upgrading from an earlier release such as 5.18.0, first read
L<perl5200delta>, which describes differences between 5.18.0 and 5.20.0.

=head1 Incompatible Changes

There are no changes intentionally incompatible with 5.20.0.  If any exist,
they are bugs, and we request that you submit a report.  See L</Reporting Bugs>
below.

=head1 Performance Enhancements

=over 4

=item *

An optimization to avoid problems with COW and deliberately overallocated PVs
has been disabled because it interfered with another, more important,
optimization, causing a slowdown on some platforms.
L<[perl #121975]|https://rt.perl.org/Ticket/Display.html?id=121975>

=item *

Returning a string from a lexical variable could be slow in some cases.  This
has now been fixed.
L<[perl #121977]|https://rt.perl.org/Ticket/Display.html?id=121977>

=back

=head1 Modules and Pragmata

=head2 Updated Modules and Pragmata

=over 4

=item *

L<Config::Perl::V> has been upgraded from version 0.20 to 0.22.

The list of Perl versions covered has been updated and some flaws in the
parsing have been fixed.

=item *

L<Exporter> has been upgraded from version 5.70 to 5.71.

Illegal POD syntax in the documentation has been corrected.

=item *

L<ExtUtils::CBuilder> has been upgraded from version 0.280216 to 0.280217.

Android builds now link to both B<-lperl> and C<$Config::Config{perllibs}>.

=item *

L<File::Copy> has been upgraded from version 2.29 to 2.30.

The documentation now notes that C<copy> will not overwrite read-only files.

=item *

L<Module::CoreList> has been upgraded from version 3.11 to 5.020001.

The list of Perl versions covered has been updated.

=item *

The PathTools module collection has been upgraded from version 3.47 to 3.48.

Fallbacks are now in place when cross-compiling for Android and
C<$Config::Config{sh}> is not yet defined.
L<[perl #121963]|https://rt.perl.org/Ticket/Display.html?id=121963>

=item *

L<PerlIO::via> has been upgraded from version 0.14 to 0.15.

A minor portability improvement has been made to the XS implementation.

=item *

L<Unicode::UCD> has been upgraded from version 0.57 to 0.58.

The documentation includes many clarifications and fixes.

=item *

L<utf8> has been upgraded from version 1.13 to 1.13_01.

The documentation has some minor formatting improvements.

=item *

L<version> has been upgraded from version 0.9908 to 0.9909.

External libraries and Perl may have different ideas of what the locale is.
This is problematic when parsing version strings if the locale's numeric
separator has been changed.  Version parsing has been patched to ensure it
handles the locales correctly.
L<[perl #121930]|https://rt.perl.org/Ticket/Display.html?id=121930>

=back

=head1 Documentation

=head2 Changes to Existing Documentation

=head3 L<perlapi>

=over 4

=item *

C<av_len> - Emphasize that this returns the highest index in the array, not the
size of the array.
L<[perl #120386]|https://rt.perl.org/Ticket/Display.html?id=120386>

=item *

Note that C<SvSetSV> doesn't do set magic.

=item *

C<sv_usepvn_flags> - Fix documentation to mention the use of C<NewX> instead of
C<malloc>.
L<[perl #121869]|https://rt.perl.org/Ticket/Display.html?id=121869>

=item *

Clarify where C<NUL> may be embedded or is required to terminate a string.

=back

=head3 L<perlfunc>

=over 4

=item *

Clarify the meaning of C<-B> and C<-T>.

=item *

C<-l> now notes that it will return false if symlinks aren't supported by the
file system.
L<[perl #121523]|https://rt.perl.org/Ticket/Display.html?id=121523>

=item *

Note that C<each>, C<keys> and C<values> may produce different orderings for
tied hashes compared to other perl hashes.
L<[perl #121404]|https://rt.perl.org/Ticket/Display.html?id=121404>

=item *

Note that C<exec LIST> and C<system LIST> may fall back to the shell on Win32.
Only C<exec PROGRAM LIST> and C<system PROGRAM LIST> indirect object syntax
will reliably avoid using the shell.  This has also been noted in L<perlport>.
L<[perl #122046]|https://rt.perl.org/Ticket/Display.html?id=122046>

=item *

Clarify the meaning of C<our>.
L<[perl #122132]|https://rt.perl.org/Ticket/Display.html?id=122132>

=back

=head3 L<perlguts>

=over 4

=item *

Explain various ways of modifying an existing SV's buffer.
L<[perl #116925]|https://rt.perl.org/Ticket/Display.html?id=116925>

=back

=head3 L<perlpolicy>

=over 4

=item *

We now have a code of conduct for the I<< p5p >> mailing list, as documented in
L<< perlpolicy/STANDARDS OF CONDUCT >>.

=back

=head3 L<perlre>

=over 4

=item *

The C</x> modifier has been clarified to note that comments cannot be continued
onto the next line by escaping them.

=back

=head3 L<perlsyn>

=over 4

=item *

Mention the use of empty conditionals in C<for>/C<while> loops for infinite
loops.

=back

=head3 L<perlxs>

=over 4

=item *

Added a discussion of locale issues in XS code.

=back

=head1 Diagnostics

The following additions or changes have been made to diagnostic output,
including warnings and fatal error messages.  For the complete list of
diagnostic messages, see L<perldiag>.

=head2 Changes to Existing Diagnostics

=over 4

=item *

L<Variable length lookbehind not implemented in regex mE<sol>%sE<sol>|perldiag/"Variable length lookbehind not implemented in regex m/%s/">

Information about Unicode behaviour has been added.

=back

=head1 Configuration and Compilation

=over 4

=item *

Building Perl no longer writes to the source tree when configured with
F<Configure>'s B<-Dmksymlinks> option.
L<[perl #121585]|https://rt.perl.org/Ticket/Display.html?id=121585>

=back

=head1 Platform Support

=head2 Platform-Specific Notes

=over 4

=item Android

Build support has been improved for cross-compiling in general and for Android
in particular.

=item OpenBSD

Corrected architectures and version numbers used in configuration hints when
building Perl.

=item Solaris

B<c99> options have been cleaned up, hints look for B<solstudio> as well as
B<SUNWspro>, and support for native C<setenv> has been added.

=item VMS

An old bug in feature checking, mainly affecting pre-7.3 systems, has been
fixed.

=item Windows

C<%I64d> is now being used instead of C<%lld> for MinGW.

=back

=head1 Internal Changes

=over 4

=item *

Added L<perlapi/sync_locale>.
Changing the program's locale should be avoided by XS code.  Nevertheless,
certain non-Perl libraries called from XS, such as C<Gtk> do so.  When this
happens, Perl needs to be told that the locale has changed.  Use this function
to do so, before returning to Perl.

=back

=head1 Selected Bug Fixes

=over 4

=item *

A bug has been fixed where zero-length assertions and code blocks inside of a
regex could cause C<pos> to see an incorrect value.
L<[perl #122460]|https://rt.perl.org/Ticket/Display.html?id=122460>

=item *

Using C<s///e> on tainted utf8 strings could issue bogus "Malformed UTF-8
character (unexpected end of string)" warnings.  This has now been fixed.
L<[perl #122148]|https://rt.perl.org/Ticket/Display.html?id=122148>

=item *

C<system> and friends should now work properly on more Android builds.

Due to an oversight, the value specified through B<-Dtargetsh> to F<Configure>
would end up being ignored by some of the build process.  This caused perls
cross-compiled for Android to end up with defective versions of C<system>,
C<exec> and backticks: the commands would end up looking for F</bin/sh> instead
of F</system/bin/sh>, and so would fail for the vast majority of devices,
leaving C<$!> as C<ENOENT>.

=item *

Many issues have been detected by L<Coverity|http://www.coverity.com/> and 
fixed.

=back

=head1 Acknowledgements

Perl 5.20.1 represents approximately 4 months of development since Perl 5.20.0
and contains approximately 12,000 lines of changes across 170 files from 36
authors.

Excluding auto-generated files, documentation and release tools, there were
approximately 2,600 lines of changes to 110 .pm, .t, .c and .h files.

Perl continues to flourish into its third decade thanks to a vibrant community
of users and developers.  The following people are known to have contributed
the improvements that became Perl 5.20.1:

Aaron Crane, Abigail, Alberto Simões, Alexandr Ciornii, Alexandre (Midnite)
Jousset, Andrew Fresh, Andy Dougherty, Brian Fraser, Chris 'BinGOs' Williams,
Craig A. Berry, Daniel Dragan, David Golden, David Mitchell, H.Merijn Brand,
James E Keenan, Jan Dubois, Jarkko Hietaniemi, John Peacock, kafka, Karen
Etheridge, Karl Williamson, Lukas Mai, Matthew Horsfall, Michael Bunk, Peter
Martini, Rafael Garcia-Suarez, Reini Urban, Ricardo Signes, Shirakata Kentaro,
Smylers, Steve Hay, Thomas Sibley, Todd Rinaldo, Tony Cook, Vladimir Marek,
Yves Orton.

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

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

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

=head1 Reporting Bugs

If you find what you think is a bug, you might check the articles recently
posted to the comp.lang.perl.misc newsgroup and the perl bug database at
https://rt.perl.org/ .  There may also be information at http://www.perl.org/ ,
the Perl Home Page.

If you believe you have an unreported bug, please run the L<perlbug> program
included with your release.  Be sure to trim your bug down to a tiny but
sufficient test case.  Your bug report, along with the output of C<perl -V>,
will be sent off to perlbug@perl.org to be analysed by the Perl porting team.

If the bug you are reporting has security implications, which make it
inappropriate to send to a publicly archived mailing list, then please send it
to perl5-security-report@perl.org.  This points to a closed subscription
unarchived mailing list, which includes all the core committers, who will be
able to help assess the impact of issues, figure out a resolution, and help
co-ordinate the release of patches to mitigate or fix the problem across all
platforms on which Perl is supported.  Please only use this address for
security issues in the Perl core, not for modules independently distributed on
CPAN.

=head1 SEE ALSO

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

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

The F<README> file for general stuff.

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

=cut
Commit	Line	Data
9b8ec397 SH	1	=encoding utf8
	2
	3	=head1 NAME
	4
	5	perl5201delta - what is new for perl v5.20.1
	6
	7	=head1 DESCRIPTION
	8
	9	This document describes differences between the 5.20.0 release and the 5.20.1
	10	release.
	11
	12	If you are upgrading from an earlier release such as 5.18.0, first read
	13	L<perl5200delta>, which describes differences between 5.18.0 and 5.20.0.
	14
	15	=head1 Incompatible Changes
	16
	17	There are no changes intentionally incompatible with 5.20.0. If any exist,
	18	they are bugs, and we request that you submit a report. See L</Reporting Bugs>
	19	below.
	20
	21	=head1 Performance Enhancements
	22
	23	=over 4
	24
	25	=item *
	26
	27	An optimization to avoid problems with COW and deliberately overallocated PVs
	28	has been disabled because it interfered with another, more important,
	29	optimization, causing a slowdown on some platforms.
	30	L<[perl #121975]\|https://rt.perl.org/Ticket/Display.html?id=121975>
	31
	32	=item *
	33
	34	Returning a string from a lexical variable could be slow in some cases. This
	35	has now been fixed.
	36	L<[perl #121977]\|https://rt.perl.org/Ticket/Display.html?id=121977>
	37
	38	=back
	39
	40	=head1 Modules and Pragmata
	41
	42	=head2 Updated Modules and Pragmata
	43
	44	=over 4
	45
	46	=item *
	47
	48	L<Config::Perl::V> has been upgraded from version 0.20 to 0.22.
	49
	50	The list of Perl versions covered has been updated and some flaws in the
	51	parsing have been fixed.
	52
	53	=item *
	54
	55	L<Exporter> has been upgraded from version 5.70 to 5.71.
	56
	57	Illegal POD syntax in the documentation has been corrected.
	58
	59	=item *
	60
	61	L<ExtUtils::CBuilder> has been upgraded from version 0.280216 to 0.280217.
	62
	63	Android builds now link to both B<-lperl> and C<$Config::Config{perllibs}>.
	64
65	=item *
66
67	L<File::Copy> has been upgraded from version 2.29 to 2.30.
68
69	The documentation now notes that C<copy> will not overwrite read-only files.
70
71	=item *
72
73	L<Module::CoreList> has been upgraded from version 3.11 to 5.020001.
74
75	The list of Perl versions covered has been updated.
76
77	=item *
78
79	The PathTools module collection has been upgraded from version 3.47 to 3.48.
80
81	Fallbacks are now in place when cross-compiling for Android and
82	C<$Config::Config{sh}> is not yet defined.
83	L<[perl #121963]\|https://rt.perl.org/Ticket/Display.html?id=121963>
84
85	=item *
86
87	L<PerlIO::via> has been upgraded from version 0.14 to 0.15.
88
89	A minor portability improvement has been made to the XS implementation.
90
91	=item *
92
93	L<Unicode::UCD> has been upgraded from version 0.57 to 0.58.
94
95	The documentation includes many clarifications and fixes.
96
97	=item *
98
99	L<utf8> has been upgraded from version 1.13 to 1.13_01.
100
101	The documentation has some minor formatting improvements.
102
103	=item *
104
105	L<version> has been upgraded from version 0.9908 to 0.9909.
106
107	External libraries and Perl may have different ideas of what the locale is.
108	This is problematic when parsing version strings if the locale's numeric
109	separator has been changed. Version parsing has been patched to ensure it
110	handles the locales correctly.
111	L<[perl #121930]\|https://rt.perl.org/Ticket/Display.html?id=121930>
112
113	=back
114
115	=head1 Documentation
116
117	=head2 Changes to Existing Documentation
118
119	=head3 L<perlapi>
120
121	=over 4
122
123	=item *
124
125	C<av_len> - Emphasize that this returns the highest index in the array, not the
126	size of the array.
127	L<[perl #120386]\|https://rt.perl.org/Ticket/Display.html?id=120386>
128
129	=item *
130
131	Note that C<SvSetSV> doesn't do set magic.
132
133	=item *
134
135	C<sv_usepvn_flags> - Fix documentation to mention the use of C<NewX> instead of
136	C<malloc>.
137	L<[perl #121869]\|https://rt.perl.org/Ticket/Display.html?id=121869>
138
139	=item *
140
141	Clarify where C<NUL> may be embedded or is required to terminate a string.
142
143	=back
144
145	=head3 L<perlfunc>
146
147	=over 4
148
149	=item *
150
151	Clarify the meaning of C<-B> and C<-T>.
152
153	=item *
154
155	C<-l> now notes that it will return false if symlinks aren't supported by the
156	file system.
157	L<[perl #121523]\|https://rt.perl.org/Ticket/Display.html?id=121523>
158
159	=item *
160
161	Note that C<each>, C<keys> and C<values> may produce different orderings for
162	tied hashes compared to other perl hashes.
163	L<[perl #121404]\|https://rt.perl.org/Ticket/Display.html?id=121404>
164
165	=item *
166
167	Note that C<exec LIST> and C<system LIST> may fall back to the shell on Win32.
168	Only C<exec PROGRAM LIST> and C<system PROGRAM LIST> indirect object syntax
169	will reliably avoid using the shell. This has also been noted in L<perlport>.
170	L<[perl #122046]\|https://rt.perl.org/Ticket/Display.html?id=122046>
171
172	=item *
173
174	Clarify the meaning of C<our>.
175	L<[perl #122132]\|https://rt.perl.org/Ticket/Display.html?id=122132>
176
177	=back
178
179	=head3 L<perlguts>
180
181	=over 4
182
183	=item *
184
185	Explain various ways of modifying an existing SV's buffer.
186	L<[perl #116925]\|https://rt.perl.org/Ticket/Display.html?id=116925>
187
188	=back
189
190	=head3 L<perlpolicy>
191
192	=over 4
193
194	=item *
195
196	We now have a code of conduct for the I<< p5p >> mailing list, as documented in
197	L<< perlpolicy/STANDARDS OF CONDUCT >>.
198
199	=back
200
201	=head3 L<perlre>
202
203	=over 4
204
205	=item *
206
207	The C</x> modifier has been clarified to note that comments cannot be continued
208	onto the next line by escaping them.
209
210	=back
211
212	=head3 L<perlsyn>
213
214	=over 4
215
216	=item *
217
218	Mention the use of empty conditionals in C<for>/C<while> loops for infinite
219	loops.
220
221	=back
222
223	=head3 L<perlxs>
224
225	=over 4
226
227	=item *
228
229	Added a discussion of locale issues in XS code.
230
231	=back
232
233	=head1 Diagnostics
234
235	The following additions or changes have been made to diagnostic output,
236	including warnings and fatal error messages. For the complete list of
237	diagnostic messages, see L<perldiag>.
238
239	=head2 Changes to Existing Diagnostics
240
241	=over 4
242
243	=item *
244
245	L<Variable length lookbehind not implemented in regex mE<sol>%sE<sol>\|perldiag/"Variable length lookbehind not implemented in regex m/%s/">
246
247	Information about Unicode behaviour has been added.
248
249	=back
250
251	=head1 Configuration and Compilation
252
253	=over 4
254
255	=item *
256
257	Building Perl no longer writes to the source tree when configured with
258	F<Configure>'s B<-Dmksymlinks> option.
259	L<[perl #121585]\|https://rt.perl.org/Ticket/Display.html?id=121585>
260
261	=back
262
263	=head1 Platform Support
264
265	=head2 Platform-Specific Notes
266
267	=over 4
268
269	=item Android
270
271	Build support has been improved for cross-compiling in general and for Android
272	in particular.
273
274	=item OpenBSD
275
276	Corrected architectures and version numbers used in configuration hints when
277	building Perl.
278
279	=item Solaris
280
281	B<c99> options have been cleaned up, hints look for B<solstudio> as well as
282	B<SUNWspro>, and support for native C<setenv> has been added.
283
284	=item VMS
285
286	An old bug in feature checking, mainly affecting pre-7.3 systems, has been
287	fixed.
288
289	=item Windows
290
291	C<%I64d> is now being used instead of C<%lld> for MinGW.
292
293	=back
294
295	=head1 Internal Changes
296
297	=over 4
298
299	=item *
300
301	Added L<perlapi/sync_locale>.
302	Changing the program's locale should be avoided by XS code. Nevertheless,
303	certain non-Perl libraries called from XS, such as C<Gtk> do so. When this
304	happens, Perl needs to be told that the locale has changed. Use this function
305	to do so, before returning to Perl.
306
307	=back
308
309	=head1 Selected Bug Fixes
310
311	=over 4
312
313	=item *
314
315	A bug has been fixed where zero-length assertions and code blocks inside of a
316	regex could cause C<pos> to see an incorrect value.
317	L<[perl #122460]\|https://rt.perl.org/Ticket/Display.html?id=122460>
318
319	=item *
320
321	Using C<s///e> on tainted utf8 strings could issue bogus "Malformed UTF-8
322	character (unexpected end of string)" warnings. This has now been fixed.
323	L<[perl #122148]\|https://rt.perl.org/Ticket/Display.html?id=122148>
324
325	=item *
326
327	C<system> and friends should now work properly on more Android builds.
328
329	Due to an oversight, the value specified through B<-Dtargetsh> to F<Configure>
330	would end up being ignored by some of the build process. This caused perls
331	cross-compiled for Android to end up with defective versions of C<system>,
332	C<exec> and backticks: the commands would end up looking for F</bin/sh> instead
333	of F</system/bin/sh>, and so would fail for the vast majority of devices,
334	leaving C<$!> as C<ENOENT>.
335
336	=item *
337
338	Many issues have been detected by L<Coverity\|http://www.coverity.com/> and
339	fixed.
340
341	=back
342
343	=head1 Acknowledgements
344
345	Perl 5.20.1 represents approximately 4 months of development since Perl 5.20.0
346	and contains approximately 12,000 lines of changes across 170 files from 36
347	authors.
348
349	Excluding auto-generated files, documentation and release tools, there were
350	approximately 2,600 lines of changes to 110 .pm, .t, .c and .h files.
351
352	Perl continues to flourish into its third decade thanks to a vibrant community
353	of users and developers. The following people are known to have contributed
354	the improvements that became Perl 5.20.1:
355
356	Aaron Crane, Abigail, Alberto Simões, Alexandr Ciornii, Alexandre (Midnite)
357	Jousset, Andrew Fresh, Andy Dougherty, Brian Fraser, Chris 'BinGOs' Williams,
358	Craig A. Berry, Daniel Dragan, David Golden, David Mitchell, H.Merijn Brand,
359	James E Keenan, Jan Dubois, Jarkko Hietaniemi, John Peacock, kafka, Karen
360	Etheridge, Karl Williamson, Lukas Mai, Matthew Horsfall, Michael Bunk, Peter
361	Martini, Rafael Garcia-Suarez, Reini Urban, Ricardo Signes, Shirakata Kentaro,
362	Smylers, Steve Hay, Thomas Sibley, Todd Rinaldo, Tony Cook, Vladimir Marek,
363	Yves Orton.
364
365	The list above is almost certainly incomplete as it is automatically generated
366	from version control history. In particular, it does not include the names of
367	the (very much appreciated) contributors who reported issues to the Perl bug
368	tracker.
369
370	Many of the changes included in this version originated in the CPAN modules
371	included in Perl's core. We're grateful to the entire CPAN community for
372	helping Perl to flourish.
373
374	For a more complete list of all of Perl's historical contributors, please see
375	the F<AUTHORS> file in the Perl source distribution.
376
377	=head1 Reporting Bugs
378
379	If you find what you think is a bug, you might check the articles recently
380	posted to the comp.lang.perl.misc newsgroup and the perl bug database at
381	https://rt.perl.org/ . There may also be information at http://www.perl.org/ ,
382	the Perl Home Page.
383
384	If you believe you have an unreported bug, please run the L<perlbug> program
385	included with your release. Be sure to trim your bug down to a tiny but
386	sufficient test case. Your bug report, along with the output of C<perl -V>,
387	will be sent off to perlbug@perl.org to be analysed by the Perl porting team.
388
389	If the bug you are reporting has security implications, which make it
390	inappropriate to send to a publicly archived mailing list, then please send it
391	to perl5-security-report@perl.org. This points to a closed subscription
392	unarchived mailing list, which includes all the core committers, who will be
393	able to help assess the impact of issues, figure out a resolution, and help
394	co-ordinate the release of patches to mitigate or fix the problem across all
395	platforms on which Perl is supported. Please only use this address for
396	security issues in the Perl core, not for modules independently distributed on
397	CPAN.
398
399	=head1 SEE ALSO
400
401	The F<Changes> file for an explanation of how to view exhaustive details on
402	what changed.
403
404	The F<INSTALL> file for how to build Perl.
405
406	The F<README> file for general stuff.
407
408	The F<Artistic> and F<Copying> files for copyright information.
409
410	=cut