X-Git-Url: https://perl5.git.perl.org/perl5.git/blobdiff_plain/531ba486567a7e92e8fadc6d5c89b5c3e2386194..ae4de4099e764f5284fc664e66a465483a959592:/pod/perldelta.pod

diff --git a/pod/perldelta.pod b/pod/perldelta.pod
index 8731d74..3cc778b 100644
--- a/pod/perldelta.pod
+++ b/pod/perldelta.pod
@@ -1,27 +1,26 @@
 =encoding utf8
 
 =for comment
-This has been completed up to 7c5c3d9b except for:
-a1da11a30dfa4f3543dcab00834ff535202f5085 (GNU/Hurd hints)
-f0d0a205cc02c769ca48d6df00f3eea304ff91d8 (similar)
-a058c51605ec2d38bf37f2e2c4f81926e3a90ea9 (Leon Timmermans; setresgid)
-928b2f01177c40be013139c657d79c631790a916 (Reini Urban; Errno)
+This has been completed up to 5dca8ed9d28, except for
+b0f2e9e nwclark     Fix two bugs related to pod files outside of pod/ (important enough?)
+43d9ecf jpeacock    Set all version object math ops to noop
+f300909 smueller    EU::ParseXS: Silence warning (probably unnecessary)
 
 =head1 NAME
 
 [ this is a template for a new perldelta file. Any text flagged as
 XXX needs to be processed before release. ]
 
-perldelta - what is new for perl v5.15.5
+perldelta - what is new for perl v5.15.6
 
 =head1 DESCRIPTION
 
-This document describes differences between the 5.15.4 release and
-the 5.15.5 release.
+This document describes differences between the 5.15.5 release and
+the 5.15.6 release.
 
-If you are upgrading from an earlier release such as 5.15.3, first read
-L<perl5154delta>, which describes differences between 5.15.3 and
-5.15.4.
+If you are upgrading from an earlier release such as 5.15.4, first read
+L<perl5155delta>, which describes differences between 5.15.4 and
+5.15.5.
 
 =head1 Notice
 
@@ -33,32 +32,32 @@ XXX New core language features go here. Summarise user-visible core language
 enhancements. Particularly prominent performance optimisations could go
 here, but most should go in the L</Performance Enhancements> section.
 
-=head2 More consistent C<eval>
+[ List each enhancement as a =head2 entry ]
 
-The C<eval> operator sometimes treats a string argument as a sequence of
-characters and sometimes as a sequence of bytes, depending on the internal
-encoding.  The internal encoding is not supposed to make any difference,
-but there is code that relies on this inconsistency.
+=head2 C<__SUB__>
 
-Under C<use v5.15> and higher, the C<unicode_eval> and C<evalbytes>
-features resolve this.  The C<unicode_eval> feature causes C<eval $string>
-to treat the string always as Unicode.  The C<evalbytes> features provides
-a function, itself called C<evalbytes>, which evaluates its argument always
-as a string of bytes.
+The new C<__SUB__> token, available under the "current_sub" feature (see
+L<feature>) or C<use v5.15>, returns a reference to the current subroutine,
+making it easier to write recursive closures.
 
-These features also fix oddities with source filters leaking to outer
-dynamic scopes.
+=head2 New option for the debugger's B<t> command
 
-See L<feature> for more detail.
+The B<t> command in the debugger, which toggles tracing mode, now accepts a
+numerical argument that determines how many levels of subroutine calls to
+trace.
 
-=head2 C<$[> is back
+=head2 Return value of C<tied>
 
-The C<$[> variable is back again, but is now implemented as a module, so
-programs that do not mention it (i.e., most of them), will not incur any
-run-time penalty.  In a later release in the 5.15 branch it might be
-disabled in the scope of C<use v5.16>.
+The value returned by C<tied> on a tied variable is now the actual scalar
+that holds the object to which the variable is tied.  This allows ties to
+be weakened with C<Scalar::Util::weaken(tied $tied_variable)>.
 
-The new implementation has some bug fixes.  See L<arybase>.
+=head2 Lvalue C<scalar>
+
+C<scalar> can now be used as an lvalue.  You might consider this a new
+feature (which is why it is listed in this section), but the author of
+the change considered it a bug fix, since C<scalar> is only supposed to be
+setting scalar context, not changing lvalueness [perl #24346].
 
 =head1 Security
 
@@ -66,7 +65,22 @@ XXX Any security-related notices go here.  In particular, any security
 vulnerabilities closed should be noted here rather than in the
 L</Selected Bug Fixes> section.
 
-[ List each security issue as a =head2 entry ]
+=head2 C<is_utf8_char()>
+
+The XS-callable function C<is_utf8_char()> when presented with malformed
+UTF-8 input can read up to 12 bytes beyond the end of the string.  This
+cannot be fixed without changing its API.  It is not called from CPAN.
+The documentation for it now describes how to use it safely.
+
+=head2 Other C<is_utf8_foo()> functions, as well as C<utf8_to_foo()>, etc.
+
+Most of the other XS-callable functions that take UTF-8 encoded input
+implicitly assume that the UTF-8 is valid (not malformed) in regards to
+buffer length.  Do not do things such as change a character's case or
+see if it is alphanumeric without first being sure that it is valid
+UTF-8.  This can be safely done for a whole string by using one of the
+functions C<is_utf8_string()>, C<is_utf8_string_loc()>, and
+C<is_utf8_string_loclen()>.
 
 =head1 Incompatible Changes
 
@@ -75,34 +89,131 @@ XXX For a release on a stable branch, this section aspires to be:
     There are no changes intentionally incompatible with 5.XXX.XXX
     If any exist, they are bugs and reports are welcome.
 
-=head2 Certain deprecated Unicode properties are no longer supported by default
+[ List each incompatible change as a =head2 entry ]
+
+=head2 C<use I<VERSION>>
+
+As of this release, version declarations like C<use v5.16> now disable all
+features before enabling the new feature bundle.  This means that the
+following holds true:
+
+    use 5.016;
+    # 5.16 features enabled here
+    use 5.014;
+    # 5.16 features disabled here
+
+C<use v5.12> and higher continue to enable strict, but explicit
+C<use strict> and C<no strict> now override the version declaration, even
+when they come first:
+
+    no strict;
+    use 5.012;
+    # no strict here
+
+There is a new ":default" feature bundle, that represents the set of
+features enabled before any version declaration or C<use feature> has been
+seen.  Version declarations below 5.10 now enable the ":default" feature
+set.  This does not actually change the behaviour of C<use v5.8>, because
+features added to the ":default" set are those that were traditionally
+enabled by default, before they could be turned off.
 
-Perl should never have exposed certain Unicode properties that are used
-by Unicode internally and not meant to be publicly available.  Use of
-these has generated deprecated warning messages since Perl 5.12.  The
-removed properties are Other_Alphabetic,
-Other_Default_Ignorable_Code_Point, Other_Grapheme_Extend,
-Other_ID_Continue, Other_ID_Start, Other_Lowercase, Other_Math, and
-Other_Uppercase.
+C<$[> is now disabled under C<use v5.16>.  It is part of the default
+feature set and can be turned on or off explicitly
+with C<use feature 'array_base'>.
+
+=head2 C<UNIVERSAL::VERSION>
+
+The change to C<UNIVERSAL::VERSION> in 5.15.2 has been reverted.  It now
+returns a stringified version object once more.
+
+=head2 C<substr> lvalue revamp
+
+When C<substr> is called in lvalue or potential lvalue context with two or
+three arguments, a special lvalue scalar is returned that modifies the
+original string (the first argument) when assigned to.
+
+Previously, the offsets (the second and third arguments) passed to
+C<substr> would be converted immediately to match the string, negative
+offsets being translated to positive and offsets beyond the end of the
+string being truncated.
+
+Now, the offsets are recorded without modification in the special lvalue
+scalar that is returned, and the original string is not even looked at by
+C<substr> itself, but only when the returned lvalue is read or modified.
+
+These changes result in several incompatible changes and bug fixes:
+
+=over
+
+=item *
 
-Perl may be recompiled to include any or all of them; instructions are
-given in
-L<perluniprops/Unicode character properties that are NOT accepted by Perl>.
+If the original string changes length after the call to C<substr> but
+before assignment to its return value, negative offsets will remember
+their position from the end of the string, affecting code like this:
 
+    my $string = "string";
+    my $lvalue = \substr $string, -4, 2;
+    print $lvalue, "\n"; # prints "ri"
+    $string = "bailing twine";
+    print $lvalue, "\n"; # prints "wi"; used to print "il"
+
+The same thing happens with an omitted third argument.  The returned lvalue
+will always extend to the end of the string, even if the string becomes
+longer.
+
+=item *
+
+Tied (and otherwise magical) variables are no longer exempt from the
+"Attempt ot use reference as lvalue in substr" warning.
+
+=item *
+
+That warning now occurs when the returned lvalue is assigned to, not when
+C<substr> itself is called.  This only makes a difference if the return
+value of C<substr> is referenced and assigned to later.
+
+=item *
+
+The order in which "uninitialized" warnings occur for arguments to
+C<substr> has changed.
+
+=item *
+
+Passing a substring of a read-only value or a typeglob to a function (potential lvalue context) no longer causes an immediate "Can't coerce" or "Modification of a read-only value" error.  That error only occurs if and
+when the value passed is assigned to.
+
+The same thing happens with the "substr outside of string" error.  If the
+lvalue is only read, not written to, it is now just a warning, as with
+rvalue C<substr>.
+
+=item *
+
+C<substr> assignments no longer call FETCH twice if the first argument is a
+tied variable, but just once.
+
+=back
 
-=head2 Dereferencing IO thingies as typeglobs
+It was impossible to fix all the bugs without an incompatible change, and
+the behaviour of negative offsets was never specified, so the change was
+deemed acceptable.
 
-The C<*{...}> operator, when passed a reference to an IO thingy (as in
-C<*{*STDIN{IO}}>), creates a new typeglob containing just that IO object.
+=head2 Return value of C<eval>
 
-Previously, it would stringify as an empty string, but some operators would
-treat it as undefined, producing an "uninitialized" warning.
+C<eval> returns C<undef> in scalar context or an empty list in list context
+when there is a run-time error.  For syntax errors (when C<eval> is passed
+a string), in list context it used to return a list containing a single
+undefined element.  Now it returns an empty list in list context for all
+errors [perl #80630].
 
-Having a typeglob appear as an empty string is a side effect of the
-implementation that has caused various bugs over the years.
+=head2 Anonymous handles
 
-The solution was to make it stringify like a normal anonymous typeglob,
-like those produced by C<open($foo->{bar}, ...)> [perl #96326].
+Automatically generated file handles are now named __ANONIO__ when the
+variable name cannot be determined, rather than $__ANONIO__.
+
+=head2 XS API tweak
+
+The C<newCONSTSUB_flags> C-level function, added in 5.15.4, now has a
+C<len> parameter.
 
 =head1 Deprecations
 
@@ -112,19 +223,6 @@ listed as an updated module in the L</Modules and Pragmata> section.
 
 [ List each deprecation as a =head2 entry ]
 
-=head2 Don't read the Unicode data base files in F<lib/unicore>
-
-It is now deprecated to directly read the Unicode data base files.
-These are stored in the F<lib/unicore> directory.  Instead, you should
-use the new functions in L<Unicode::UCD>.  These provide a stable API,
-and give complete information.  (This API is, however, subject to change
-somewhat during the 5.15 development cycle, as we gain experience and
-get feedback from using it.)
-
-Perl may at some point in the future change or remove the files.  The
-file most likely for applications to have used is F<lib/unicore/ToDigit.pl>.
-L<Unicode::UCD/prop_invmap()> can be used to get at its data instead.
-
 =head1 Performance Enhancements
 
 XXX Changes which enhance performance without changing behaviour go here. There
@@ -136,12 +234,29 @@ may well be none in a stable release.
 
 =item *
 
-Due to changes in L<File::Glob>, Perl's C<glob> function and its
-C<< <...> >> equivalent are now much faster.  The splitting of the pattern
-into words has been rewritten in C, resulting in speed-ups of 20% in some
-cases.
+Perl 5.12.0 sped up the destruction of objects whose classes define empty
+C<DESTROY> methods (to prevent autoloading), simply by not calling such
+empty methods.  This release takes this optimisation a step further, by not
+calling any C<DESTROY> method that begins with an C<return> statement.
+This can be useful for destructors that are only used for debugging:
 
-This does not affect VMS, as it does not use File::Glob.
+    use constant DEBUG => 1;
+    sub DESTROY { return unless DEBUG; ... }
+
+Constant-folding will reduce the first statement to C<return;> if DEBUG is
+set to 0, triggering this optimisation.
+
+=item *
+
+Assign to a variable that holds a typeglob or copy-on-write scalar is now
+much faster.  Previously the typeglob would be stringified or the
+copy-on-write scalar would be copied before being clobbered.
+
+=item *
+
+Assignment to a substring in void context is now more than twice its
+previous speed.  Instead of creating and returning a special lvalue scalar
+that is then assigned to, C<substr> modifies the original string itself.
 
 =back
 
@@ -163,7 +278,7 @@ cribbed.
 
 =item *
 
-L<arybase> -- this new module implements the C<$[> variable.
+XXX
 
 =back
 
@@ -173,125 +288,194 @@ L<arybase> -- this new module implements the C<$[> variable.
 
 =item *
 
-L<Archive::Extract> has been upgraded from version 0.56 to version 0.58.
+L<Archive::Tar> has been upgraded from version 1.80 to version 1.82.
+
+Adjustments to handle files >8gb (>0777777777777 octal) and a feature to
+return the MD5SUM of files in the archive.
 
 =item *
 
-L<B::Deparse> has been upgraded from version 1.08 to 1.08.
+L<AutoLoader> has been upgraded from version 5.71 to version 5.72.
 
-It now correctly deparses C<CORE::do>, C<CORE::glob> and slices of empty
-lists.
+=item *
+
+L<B::Debug> has been upgraded from version 1.16 to version 1.17.
 
 =item *
 
-L<CGI> has been upgraded from version 3.55 to version 3.58.
+L<B::Deparse> has been upgraded from version 1.09 to version 1.10.
+
+Various constructs that used to be deparsed incorrectly have been fixed:
+
+=over
+
+=item C<sort(foo(bar))>
+
+C<sort foo(bar)>, how it used to deparse, makes foo the sort routine,
+rather than a regular function call.
+
+=item Keys and values in C<%^H>
+
+Undefined values in the hint hash were being deparsed as empty strings.
+Whenever the hint hash changed, all undefined values, even those
+unmodified, were being printed.
+
+Special characters, such as quotation marks, were not being escaped
+properly.
+
+Some values used to be omitted if, for instance, a key was the same as a
+previous value and vice versa.
+
+=item "method BLOCK" syntax
+
+C<method { $expr }> used to be deparsed as something like
+C<< do{ $expr }->method >>, but the latter puts the $expr in scalar
+context, whereas the former puts in list context.
+
+=item C<do +{}> and C<do({})>
+
+These are both variants of do-file syntax, but were being deparsed as
+do-blocks.
+
+=item Keywords that do not follow the llafr
+
+Keywords like C<return> and C<last> that do not follow the
+looks-like-a-function rule are now deparsed correctly with parentheses in
+the right place.
+
+Similarly, C<not>, which I<does> follow the llafr, was being deparsed as
+though it does not.
+
+=item C<=~>
+
+In various cases, B::Deparse started adding a spurious C<$_ =~> before the
+right-hand side in Perl 5.14; e.g., C<< "" =~ <$a> >> would become
+C<< "" =~ ($_ =~ <$a>) >>.
+
+=item C<open local *FH>
+
+C<open>, C<pipe> and other functions that autovivify handles used to omit
+C<local *> from C<local *FH>.
+
+=item Negated single-letter subroutine calls
+
+Negated subroutine calls like C<- f()> and C<-(f())> were being deparsed
+as file test operators.
+
+=item C<&{&}>
 
-Use public and documented FCGI.pm API in CGI::Fast
-CGI::Fast was using an FCGI API that was deprecated and removed from
-documentation more than ten years ago. Usage of this deprecated API with
-FCGI >= 0.70 or FCGI <= 0.73 introduces a security issue.
-L<https://rt.cpan.org/Public/Bug/Display.html?id=68380>
-L<http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2011-2766>
+C<&{&}> and C<& &>, which are calls to the subroutine named "&", believe it
+or not, were being deparsed as C<&&>.
+
+=back
 
 =item *
 
-L<Compress::Raw::Bzip2> has been upgraded from version 2.037 to version 2.040.
+L<Compress::Raw::Zlib> has been upgraded from version 2.042 to version 2.045.
 
 =item *
 
-L<Compress::Raw::Zlib> has been upgraded from version 2.037 to version 2.040.
+L<Compress::Raw::Bzip2> has been upgraded from version 2.042 to version 2.045.
 
 =item *
 
-L<Compress::Zlib> has been upgraded from version 2.037 to version 2.040.
+L<CPAN::Meta::YAML> has been upgraded from version 0.004 to version 0.005.
 
 =item *
 
-L<CPANPLUS> has been upgraded from version 0.9111 to version 0.9112.
+L<CPANPLUS> has been upgraded from version 0.9112 to version 0.9113.
 
 =item *
 
-L<CPANPLUS::Dist::Build> has been upgraded from version 0.58 to version 0.60.
+L<Data::Dumper> has been upgraded from version 2.134 to version 2.135.
+
+The XS implementation has been updated to account for the Unicode symbol
+changes in Perl 5.15.4.  It also knows how to output typeglobs with nulls
+in their names.
 
 =item *
 
-L<Digest::SHA> has been upgraded from version 5.62 to version 5.63.
+L<Digest::SHA> has been upgraded from version 5.63 to version 5.70.
 
-Added code to allow very large data inputs all at once, which had previously been
-limited to several hundred megabytes at a time
+Added BITS mode to addfile method and shasum which makes partial-byte inputs
+now possible via files/STDIN and allows shasum to check all 8074 NIST Msg vectors,
+where previously special programming was required to do this.
 
 =item *
 
-L<ExtUtils::MakeMaker> has been upgraded from version 6.61_01 to version 6.63_02.
+L<Exporter> has been upgraded from version 5.65 to version 5.66.
+
+It no longer tries to localise C<$_> unnecessarily.
 
 =item *
 
-L<File::Glob> has been upgraded from version 1.13 to 1.14.
+L<ExtUtils::ParseXS> has been upgraded from version 3.05 to version 3.07.
+
+=item *
 
-It has a new C<:bsd_glob> export tag, intended to replace C<:glob>.  Like
-C<:glob> it overrides C<glob> with a function that does not split the glob
-pattern into words, but, unlike C<:glob>, it iterates properly in scalar
-context, instead of returning the last file.
+L<IO::Compress::Base> has been upgraded from version 2.042 to version 2.045.
 
-There are other changes affecting Perl's own C<glob> operator (which uses
-File::Glob internally, except on VMS).  See L</Performance Enhancements>
-and L</Selected Bug Fixes>.
+Added zipdetails utility.
 
 =item *
 
-L<HTTP::Tiny> has been upgraded from version 0.013 to version 0.016.
+L<Locale::Codes> has been upgraded from version 3.18 to version 3.20.
 
-Adds additional shorthand methods for all common HTTP verbs,
-a C<post_form()> method for POST-ing x-www-form-urlencoded data and
-a C<www_form_urlencode()> utility method.
+The code2XXX, XXX2code, all_XXX_codes, and all_XXX_names functions now support retired codes.
+All codesets may be specified by a constant or by their name now. Previously,
+they were specified only by a constant.
+The alias_code function exists for backward compatibility. It has been replaced by rename_country_code.
+The alias_code function will be removed sometime after September, 2013.
+All work is now done in the central module (Locale::Codes). Previously, some was still done in the
+wrapper modules (Locale::Codes::*) but that is gone now.
+Added Language Family codes (langfam) as defined in ISO 639-5.
 
 =item *
 
-L<perlfaq> has been upgraded from version 5.0150035 to version 5.0150036.
+L<Module::Loaded> has been uprgaded from version 0.06 to version 0.08.
+
+=item *
+
+L<Pod::LaTeX> has been upgraded from version 0.59 to version 0.60.
+
+Added another LaTeX escape: --- => -{}-{}-
+
+Pod::LaTeX doesn't handle -- in PODs specially, passing it directly to
+LaTeX, which then proceeds to replace it with a single -. This patch
+replaces ----- with -{}-{}-{}-{}-
 
 =item *
 
-L<Socket> as been upgraded from version 1.94_01 to 1.94_02.
+L<POSIX> has been upgraded from version 1.26 to version 1.27.
 
-It has new functions and constants for handling IPv6 sockets:
+It no longer produces a "Constant subroutine TCSANOW redefined" warning on
+Windows.
 
-    pack_ipv6_mreq
-    unpack_ipv6_mreq
-    IPV6_ADD_MEMBERSHIP
-    IPV6_DROP_MEMBERSHIP
-    IPV6_MTU
-    IPV6_MTU_DISCOVER
-    IPV6_MULTICAST_HOPS
-    IPV6_MULTICAST_IF
-    IPV6_MULTICAST_LOOP
-    IPV6_UNICAST_HOPS
-    IPV6_V6ONLY
+XXX When did it start producing that warning?  Was it post-5.15.5?  Even if
+it was not, adding a note will help whoever compiles perl5160delta.
 
 =item *
 
-L<Storable> has been upgraded from version 2.32 to 2.33.
+L<Socket> has been upgraded from version 1.94_02 to version 1.97.
+
+=item *
 
-The ability to add a fake entry to %INC to prevent Log::Agent from loading
-has been restored.  In version 2.27 (included with perl 5.14.0), Storable
-starting producing an error instead.
+L<threads> has been upgraded from version 1.85 to version 1.86.
 
 =item *
 
-L<Unicode::Collate> has been upgraded from version 0.80 to version 0.84.
+L<Unicode::Collate> has been upgraded from version 0.85 to version 0.87.
 
-Locales updated to CLDR 2.0: mk, mt, nb, nn, ro, ru, sk, sr, sv, uk
-Newly supported locales: fa, ml, mr, or, pa, si, si__dictionary,
-sr_Latn, sv__reformed, ta, te, th, ur, wae.
+Tailored compatibility ideographs as well as unified ideographs for
+the locales: ja, ko, zh__big5han, zh__gb2312han, zh__pinyin, zh__stroke.
+
+Now Locale/*.pl files are searched in @INC.
 
 =item *
 
-L<Unicode::UCD> has been upgraded from version 0.36 to version 0.37.
-This adds four new functions:  C<prop_aliases()>, and
-C<prop_value_aliases()> which are used to find all the Unicode-approved
-synonyms for property names, or to convert from one name to another;
-C<prop_invlist> which returns all the code points matching a given
-Unicode binary property; and C<prop_invmap> which returns the complete
-specification of a given Unicode property.
+L<UNIVERSAL> has been upgraded from version 1.10 to version 1.11.
+
+Documentation change clarifies return values from UNIVERSAL::VERSION.
 
 =back
 
@@ -301,7 +485,13 @@ specification of a given Unicode property.
 
 =item *
 
-XXX
+Changing the case of a UTF-8 encoded string under C<use locale> now
+gives better, but still imperfect, results.  Previously, such a string
+would entirely lose locale semantics and silently be treated as Unicode.
+Now, the code points that are less than 256 are treated with locale
+rules, while those above 255 are, of course, treated as Unicode.  See
+L<perlfunc/lc> for more details, including the deficiencies of this
+scheme.
 
 =back
 
@@ -324,13 +514,16 @@ XXX Changes which significantly change existing files in F<pod/> go here.
 However, any changes to F<pod/perldiag.pod> should go in the L</Diagnostics>
 section.
 
-=head3 L<XXX>
+=head3 L<perlsec/Laundering and Detecting Tainted Data>
 
 =over 4
 
 =item *
 
-XXX Description of the change here
+The example function for checking for taintedness contained a subtle
+error.  C<$@> needs to be localized to prevent its changing this
+global's value outside the function.  The preferred method to check for
+this, though, remains to use L<Scalar::Util/tainted>.
 
 =back
 
@@ -371,11 +564,7 @@ XXX L<message|perldiag/"message">
 
 =item *
 
-L<$[ used in %s (did you mean $] ?)|perldiag/"$[ used in %s (did you mean $] ?)">
-
-This new warning exists to catch the mistaken use of C<$[> in version
-checks.  C<$]>, not C<$[>, contains the version number.  C<$[> in a numeric
-comparison is almost always wrong.
+XXX L<message|perldiag/"message">
 
 =back
 
@@ -387,7 +576,20 @@ XXX Changes (i.e. rewording) of diagnostic messages go here
 
 =item *
 
-XXX Describe change here
+Redefinition warnings for constant subroutines used to be mandatory, even
+occurring under C<no warnings>.  Now they respect the L<warnings> pragma.
+
+=item *
+
+The "Attempt to free non-existent shared string" has had the spelling of
+"non-existent" corrected to "nonexistent".  It was already listed with the
+correct spelling in L<perldiag>.
+
+=item *
+
+The 'Use of "foo" without parentheses is ambiguous' warning has been
+extended to apply also to user-defined subroutines with a (;$) prototype,
+and not just to built-in functions.
 
 =back
 
@@ -400,16 +602,14 @@ here. Most of these are built within the directories F<utils> and F<x2p>.
 entries for each change
 Use L<XXX> with program names to get proper documentation linking. ]
 
-=head3 L<XXX>
+=head3 L<zipdetails>
 
 =over 4
 
 =item *
 
-F<pod/buildtoc>, used by the build process to build L<perltoc>, has been
-refactored and simplified. It now only contains code to build L<perltoc>;
-the code to regenerate Makefiles has been moved to F<Porting/pod_rules.pl>.
-It's a bug if this change has any material affect on the build process.
+L<zipdetails> displays information about the internal record structure of the zip file.
+It is not concerned with displaying any details of the compressed data stored in the zip file.
 
 =back
 
@@ -426,7 +626,21 @@ L</Platform Support> section, instead.
 
 =item *
 
-XXX
+F<pod/roffitall> is now build by F<pod/buildtoc>, instead of being shipped
+with the distribution. Its list of manpages is now generated (and therefore
+current). See also RT #103202 for an unresolved related issue.
+
+=item *
+
+Perl 5.15.5 had a bug in its installation script, which did not install
+F<unicore/Name.pm>.  This has been corrected [perl #104226].
+
+XXX Is that Perl version correct?  Is the file path correct?
+
+=item *
+
+The -Dusesitecustomize and -Duserelocatableinc options now work together
+properly.
 
 =back
 
@@ -444,7 +658,10 @@ that they represent may be covered elsewhere.
 
 =item *
 
-XXX
+The F<substr.t> and F<substr_thr.t> scripts for testing C<substr> have been
+moved under F<t/op/>, where they were originally.  They had been moved
+under F<t/re/> along with the substitution tests when that directory was
+created.
 
 =back
 
@@ -489,11 +706,27 @@ and compilation changes or changes in portability/compatibility.  However,
 changes within modules for platforms should generally be listed in the
 L</Modules and Pragmata> section.
 
+=head3 VMS
+
 =over 4
 
-=item XXX-some-platform
+=item *
 
-XXX
+A link-time error on VMS versions without C<symlink> support was
+introduced in 5.15.1, but has now been corrected.
+
+=item *
+
+Explicit support for VMS versions prior to v7.0 and DEC C versions prior
+to v6.0 has been removed.
+
+=item *
+
+Since Perl 5.10.1, the home-grown C<stat> wrapper has been unable to
+distinguish between a directory name containing an underscore and an
+otherwise-identical filename containing a dot in the same position
+(e.g., t/test_pl as a directory and t/test.pl as a file). This problem
+has been corrected.
 
 =back
 
@@ -509,7 +742,7 @@ be noted as well.
 
 =item *
 
-C<PL_curstash> is now reference-counted.
+XXX
 
 =back
 
@@ -525,129 +758,193 @@ L</Modules and Pragmata>.
 
 =item *
 
-Perl now holds an extra reference count on the package that code is
-currently compiling in.  This means that the following code no longer crashes [perl #101486]:
+RT #78266: The regex engine has been leaking memory when accessing
+named captures that weren't matched as part of a regex ever since 5.10
+when they were introduced, e.g. this would consume over a hundred MB
+of memory:
+
+    for (1..10_000_000) {
+	if ("foo" =~ /(foo|(?<capture>bar))?/) {
+	    my $capture = $+{capture}
+	}
+    }
+    system "ps -o rss $$"'
+
+=item *
+
+A constant subroutine assigned to a glob whose name contains a null will no
+longer cause extra globs to pop into existence when the constant is
+referenced under its new name.
+
+=item *
+
+C<sort> was not treating C<sub {}> and C<sub {()}> as equivalent when such
+a sub was provided as the comparison routine.  It used to croak on
+C<sub {()}>.
+
+=item *
+
+Subroutines from the C<autouse> namespace are once more exempt from
+redefinition warnings.  This used to work in 5.005, but was broken in 5.6
+for most subroutines.  For subs created via XS that redefine subroutines
+from the C<autouse> package, this stopped working in 5.10.
+
+=item *
+
+New XSUBs now produce redefinition warnings if they overwrite existing
+subs, as they did in 5.8.x.  (The C<autouse> logic was reversed in 5.10-14.
+Only subroutines from the C<autouse> namespace would warn when clobbered.)
+
+=item *
+
+Redefinition warnings triggered by the creation of XSUBs now respect
+Unicode glob names, instead of using the internal representation.  This was
+missed in 5.15.4, partly because this warning was so hard to trigger.  (See
+the previous item.)
+
+=item *
+
+C<newCONSTSUB> used to use compile-time warning hints, instead of run-time
+hints.  The following code should never produce a redefinition warning, but
+it used to, if C<newCONSTSUB> redefine and existing subroutine:
 
-    package Foo;
-    BEGIN {*Foo:: = *Bar::}
-    sub foo;
+    use warnings;
+    BEGIN {
+	no warnings;
+	some_XS_function_that_calls_new_CONSTSUB();
+    }
 
 =item *
 
-F<dumpvar.pl>, and consequently the C<x> command in the debugger, have been
-fixed to handle objects blessed into classes whose names contain "=".  The
-contents of such objects used not to be dumped [perl #101814].
+Redefinition warnings for constant subroutines are on by default (what are
+known as severe warnings in L<perldiag>).  This was only the case when it
+was a glob assignment or declaration of a Perl subroutine that caused the
+warning.  If the creation of XSUBs triggered the warning, it was not a
+default warning.  This has been corrected.
 
 =item *
 
-The C<x> repetition operator no longer crashes on 64-bit builds with large
-repeate counts [perl #94560].
+The internal check to see whether a redefinition warning should occur used
+to emit "uninitialized" warnings in cases like this:
+
+    use warnings "uninitialized";
+    use constant {u=>undef,v=>undef};
+    sub foo(){u} sub foo(){v}
 
 =item *
 
-A fix to C<glob> under miniperl (used to configure modules when perl itself
-is built) in Perl 5.15.3 stopped C<< <~> >> from returning the home
-directory, because it cleared %ENV before calling csh.  Now C<$ENV{HOME}>
-is preserved.  This fix probably does not affect anything.  If
-L<File::Glob> fails to load for some reason, Perl reverts to using csh.
-So it would apply in that case.
+A bug fix in Perl 5.14 introduced a new bug, causing "uninitialized"
+warnings to report the wrong variable if the operator in question has
+two operands and one is C<%{...}> or C<@{...}>.  This has been fixed
+[perl #103766].
 
 =item *
 
-On OSes other than VMS, Perl's C<glob> operator (and the C<< <...> >> form)
-use L<File::Glob> underneath.  L<File::Glob> splits the pattern into words,
-before feeding each word to its C<bsd_glob> function.
+C<< version->new("version") >> and C<printf "%vd", "version"> no longer
+crash [perl #102586].
+
+=item *
+
+C<$tied =~ y/a/b/>, C<chop $tied> and C<chomp $tied> now call FETCH just
+once when $tied holds a reference.
+
+=item *
+
+Four-argument C<select> now always calls FETCH on tied arguments.  It used
+to skip the call if the tied argument happened to hold C<undef> or a
+typeglob.
+
+=item *
+
+Four-argument C<select> no longer produces its "Non-string passed as
+bitmask" warning on tied or tainted variables that are strings.
+
+=item *
 
-There were several inconsistencies in the way the split was done.  Now
-quotation marks (' and ") are always treated as shell-style word delimiters
-(that allow whitespace as part of a word) and backslashes are always
-preserved, unless they exist to escape quotation marks.  Before, those
-would only sometimes be the case, depending on whether the pattern
-contained whitespace.  Also, escaped whitespace at the end of the pattern
-is no longer stripped [perl #40470].
+C<sysread> now always calls FETCH on the buffer passed to it if it is tied.
+It used to skip the call if the tied variable happened to hold a typeglob.
 
 =item *
 
-C<CORE::glob> now works as a way to call the default globbing function.  It
-used to respect overrides, despite the C<CORE::> prefix.
+C<< $tied .= <> >> now calls FETCH once on C<$tied>.  It used to call it
+multiple times if the last value assigned to or returned from the tied
+variable was anything other than a string or typeglob.
 
 =item *
 
-In 5.14, C</[[:lower:]]/i> and C</[[:upper:]]/i> no longer matched the
-opposite case.  This has been fixed [perl #101970].
+The C<evalbytes> keyword added in 5.15.5 was respecting C<use utf8>
+declarations from the outer scope, when it should have been ignoring them.
 
 =item *
 
-A regular expression match with an overloaded object on the right-hand side
-would in some cases stringify the object too many times.
+C<goto &func> no longers crashes, but produces an error message, when the
+unwinding of the current subroutine's scope fires a destructor that
+undefines the subroutine being "goneto" [perl #99850].
 
 =item *
 
-The C-level C<pregcomp> function could become confused as to whether the
-pattern was in UTF8 if the pattern was an overloaded, tied, or otherwise
-magical scalar [perl #101940].
+Arithmetic assignment (C<$left += $right>) involving overloaded objects that
+rely on the 'nomethod' override no longer segfault when the left operand is not
+overloaded.
 
 =item *
 
-A regression has been fixed that was introduced in 5.14, in C</i>
-regular expression matching, in which a match improperly fails if the
-pattern is in UTF-8, the target string is not, and a Latin-1 character
-precedes a character in the string that should match the pattern.  [perl
-#101710]
+Assigning C<__PACKAGE__> or any other shared hash key scalar to a stash
+element no longer causes a double free.  Regardless of this change, the
+results of such assignments are still undefined.
 
 =item *
 
-C<@{"..."} = reverse ...> started crashing in 5.15.3.  This has been fixed.
+Creating a C<UNIVERSAL::AUTOLOAD> sub no longer stops C<%+>, C<%-> and
+C<%!> from working some of the time [perl #105024].
 
 =item *
 
-C<ref> in a tainted expression started producing an "sv_upgrade" error in
-5.15.4.  This has been fixed.
+Assigning C<__PACKAGE__> or another shared hash key string to a variable no
+longer stops that variable from being tied if it happens to be a PVMG or
+PVLV internally.
 
 =item *
 
-Weak references to lexical hashes going out of scope were not going stale
-(becoming undefined), but continued to point to the hash.
+When presented with malformed UTF-8 input, the XS-callable functions
+C<is_utf8_string()>, C<is_utf8_string_loc()>, and
+C<is_utf8_string_loclen()> could read beyond the end of the input
+string by up to 12 bytes.  This no longer happens.  [perl #32080].
+However, currently, C<is_utf8_char()> still has this defect,
+see L</is_utf8_char()> above.
 
 =item *
 
-Weak references to lexical variables going out of scope are now broken
-before any magical methods (e.g., DESTROY on a tie object) are called.
-This prevents such methods from modifying the variable that will be seen
-the next time the scope is entered.
+Doing a substitution on a tied variable returning a copy-on-write scalar
+used to cause an assertion failure or an "Attempt to free nonexistent
+shared string" warning.
 
 =item *
 
-A C<keys> optimisation in Perl 5.12.0 to make it faster on empty hashes
-caused C<each> not to reset the iterator if called after the last element
-was deleted.  This has been fixed.
+A change in perl 5.15.4 caused C<caller()> to produce malloc errors and a
+crash with Perl's own malloc, and possibly with other malloc
+implementations, too [perl #104034].
 
 =item *
 
-The C<#line 42 foo> directive used not to update the arrays of lines used
-by the debugger if it occurred in a string eval.  This was partially fixed
-in 5.14, but it only worked for a single C<#line 42 foo> in each eval.  Now
-it works for multiple.
+A bug fix in 5.15.5 could sometimes result in assertion failures under
+debugging builds of perl for certain syntax errors in C<eval>, such as
+C<eval(q|""!=!~//|);>
 
 =item *
 
-String eval used not to localise C<%^H> when compiling its argument if it
-was empty at the time the C<eval> call itself was compiled.  This could
-lead to scary side effects, like C<use re "/m"> enabling other flags that
-the surrounding code was trying to enable for its caller [perl #68750].
+The "c [line num]" debugger command was broken by other debugger changes
+release in 5.15.3. This is now fixed.
 
 =item *
 
-Creating a BEGIN block from XS code (via C<newXS> or C<newATTRSUB>) would,
-on completion, make the hints of the current compiling code the current
-hints.  This could cause warnings to occur in a non-warning scope.
+Breakpoints were not properly restored after a debugger restart using the
+"R" command. This was broken in 5.15.3. This is now fixed.
 
 =item *
 
-C<eval $string> and C<require> no longer localise hints (C<$^H> and C<%^H>)
-at run time, but only during compilation of the $string or required file.
-This makes C<BEGIN { $^H{foo}=7 }> equivalent to
-C<BEGIN { eval '$^H{foo}=7' }> [perl #70151].
+The debugger prompt did not display the current line in. This was broken in
+5.15.3. This is now fixed.
 
 =back
 
@@ -679,7 +976,7 @@ here.
 
 XXX Generate this with:
 
-  perl Porting/acknowledgements.pl v5.15.4..HEAD
+  perl Porting/acknowledgements.pl v5.15.5..HEAD
 
 =head1 Reporting Bugs