perldelta: merge in changes from perl5238delta

1 files changed, 296 insertions, 0 deletions

diff --git a/Porting/perl5240delta.pod b/Porting/perl5240delta.pod
index 6f31a52415..68bc9e07e5 100644
--- a/Porting/perl5240delta.pod
+++ b/Porting/perl5240delta.pod
@@ -78,6 +78,13 @@ That is, C<< sprintf '|%.*2$|', 2, 3 >> now returns C<|002|>. This extends
 the existing reordering mechanism (which allows reordering for arguments
 that are used as format fields, widths, and vector separators).
 
+=head2 More fields provided to C<sigaction> callback with C<SA_SIGINFO>
+
+When passing the C<SA_SIGINFO> flag to L<sigaction|POSIX/sigaction>, the
+C<errno>, C<status>, C<uid>, C<pid>, C<addr> and C<band> fields are now
+included in the hash passed to the handler, if supported by the
+platform.
+
 =head1 Security
 
 =head2 fix out of boundary access in Win32 path handling
@@ -95,8 +102,27 @@ L<[perl #126862]|https://rt.perl.org/Ticket/Display.html?id=126862>
 Added validation that will detect both a short salt and invalid characters
 in the salt.  L<[perl #126922]|https://rt.perl.org/Ticket/Display.html?id=126922>
 
+=head2 Set proper umask before calling C<mkstemp(3)>
+
+In 5.22 perl started setting umask to 0600 before calling C<mkstemp(3)>
+and restoring it afterwards. This wrongfully tells open(2) to strip
+the owner read and write bits from the given mode before applying it,
+rather than the intended negation of leaving only those bits in place.
+
+Systems that use mode 0666 in C<mkstemp(3)> (like old versions of
+glibc) create a file with permissions 0066, leaving world read and
+write permissions regardless of current umask.
+
+This has been fixed by using umask 0177 instead. [perl #127322]
+
 =head1 Incompatible Changes
 
+=head2 C<qr/\N{}/> now disallowed under C<use re "strict">
+
+An empty C<\N{}> makes no sense, but for backwards compatibility is
+silently accepted as doing nothing.  But now this is a fatal error under
+the experimental feature L<re/'strict' mode>.
+
 =head2 C<qr/\b{wb}/> is now tailored to Perl expectations
 
 This is now more suited to be a drop-in replacement for plain C<\b>, but
@@ -250,6 +276,19 @@ are called on handle with the C<:utf8> layer.
 
 =item *
 
+The overhead of scope entry and exit has been considerably reduced, so
+for example subroutine calls, loops and basic blocks are all faster now.
+This empty function call now takes about a third less time to execute:
+
+    sub f{} f();
+
+=item *
+
+On Win32, C<stat>ing or C<-X>ing a path, if the file or directory does not
+exist, is now 3.5x faster on a SSD (or any drive) than before.
+
+=item *
+
 Many languages, such as Chinese, are caseless.  Perl now knows about
 most modern commercially important ones, and skips much of the work when
 a program tries to change case in them (like C<ucfirst()>) or match
@@ -456,6 +495,28 @@ exports anything.  [perl #125410]
 
 =head2 Changes to Existing Documentation
 
+=head3 L<perlguts>
+
+=over 4
+
+=item *
+
+A new section has been added, L<perlguts/"Dynamic Scope and the Context
+Stack">, which explains how the perl context stack works.
+
+=back
+
+=head3 L<perlmodlib>
+
+=over 4
+
+=item *
+
+We now recommend contacting the module-authors list or PAUSE in seeking
+guidance on the naming of modules.
+
+=back
+
 =head3 L<perlsyn>
 
 =over 4
@@ -718,6 +779,11 @@ L<Character following \p must be '{' or a single-character Unicode property name
 
 =item *
 
+L<Empty \%c in regex; marked by E<lt>-- HERE in mE<sol>%sE<sol>
+|perldiag/"Empty \%c in regex; marked by <-- HERE in mE<sol>%sE<sol>">
+
+=item *
+
 L<Illegal user-defined property name|perldiag/"Illegal user-defined property name">
 
 =item *
@@ -731,6 +797,16 @@ zeroes or overflows perl's unsigned integer representation.
 
 L<<< Sequence (?... not terminated in regex; marked by S<<-- HERE> in mE<sol>%sE<sol>|perldiag/"Sequence (?... not terminated in regex; marked by <-- HERE in mE<sol>%sE<sol>" >>>
 
+=item *
+
+L<<< Sequence (?PE<lt>... not terminated in regex; marked by E<lt>-- HERE in mE<sol>%sE<sol>
+|perldiag/"Sequence (?PE<lt>... not terminated in regex; marked by <-- HERE in mE<sol>%sE<sol>" >>>
+
+=item *
+
+L<Sequence (?PE<gt>... not terminated in regex; marked by E<lt>-- HERE in mE<sol>%sE<sol>
+|perldiag/"Sequence (?PE<gt>... not terminated in regex; marked by <-- HERE in mE<sol>%sE<sol>">
+
 =back
 
 =head3 New Warnings
@@ -739,6 +815,11 @@ L<<< Sequence (?... not terminated in regex; marked by S<<-- HERE> in mE<sol>%sE
 
 =item *
 
+L<Assuming NOT a POSIX class since %s in regex; marked by E<lt>-- HERE in mE<sol>%sE<sol>|
+perldiag/Assuming NOT a POSIX class since %s in regex; marked by <-- HERE in mE<sol>%sE<sol>>
+
+=item *
+
 L<%s() is deprecated on :utf8 handles|perldiag/"%s() is deprecated on :utf8 handles">
 
 (W deprecated) The sysread(), recv(), syswrite() and send() operators
@@ -801,6 +882,18 @@ L<< Out of memory during stack extend|perldiag/"Out of memory during %s extend"
 
 =item *
 
+The GNU Make makefile for Win32 now supports parallel builds.  [perl #126632]
+
+=item *
+
+You can now build perl with MSVC++ on Win32 using GNU Make.  [perl #126632]
+
+=item *
+
+Bison 3.0 is now supported.
+
+=item *
+
 F<Configure> no longer probes for F<libnm> by default.  Originally
 this was the "New Math" library, but the name has been re-used by the
 GNOME NetworkManager.
@@ -953,6 +1046,20 @@ negative pid like so:
 
 to signal all processes in the same group as C<$pid>.
 
+=item *
+
+For those C<%ENV> elements based on the CRTL environ array, we've always
+preserved case when setting them but did look-ups only after upcasing the
+key first, which made lower- or mixed-case entries go missing. This problem
+has been corrected by making C<%ENV> elements derived from the environ array
+case-sensitive on look-up as well as case-preserving on store.
+
+=item *
+
+Environment look-ups for C<PERL5LIB> and C<PERLLIB> previously only
+considered logical names, but now consider all sources of C<%ENV> as
+determined by C<PERL_ENV_TABLES> and as documented in L<perlvms/%ENV>.
+
 =back
 
 =item FreeBSD
@@ -1006,6 +1113,11 @@ During miniperl's process startup, during the build process, 4 to 8 IO calls
 related to the process starting F<.pl> and the F<buildcustomize.pl> file were
 removed from the code opening and executing the first 1 or 2 F<.pl> files.
 
+=item *
+
+Builds using Microsoft Visual C++ 2003 and earlier no longer produce
+an "INTERNAL COMPILER ERROR" message.  [perl #126045]
+
 =back
 
 =item EBCDIC
@@ -1125,6 +1237,107 @@ Perl 5.22.1.
 
 =item *
 
+The implementation of perl's context stack system, and its internal API,
+have been heavily reworked. Note that no significant changes have been
+made to any external APIs, but XS code which relies on such internal
+details may need to be fixed. The main changes are:
+
+=over 4
+
+=item *
+
+The C<PUSHBLOCK()>, C<POPSUB()> etc. macros have been replaced with static
+inline functions such as C<cx_pushblock()>, C<cx_popsub()> etc. These use
+function args rather than implicitly relying on local vars such as
+C<gimme> and C<newsp> being available. Also their functionality has
+changed: in particular, C<cx_popblock()> no longer decrements
+C<cxstack_ix>. The ordering of the steps in the C<pp_leave*> functions
+involving C<cx_popblock()>, C<cx_popsub()> etc. has changed. See the new
+documentation, L<perlguts/"Dynamic Scope and the Context Stack">, for
+details on how to use them.
+
+=item *
+
+Various macros, which now consistently have a CX_ prefix, have been added:
+
+  CX_CUR(), CX_LEAVE_SCOPE(), CX_POP()
+
+or renamed:
+
+  CX_POP_SAVEARRAY(), CX_DEBUG(), CX_PUSHSUBST(), CX_POPSUBST()
+
+=item *
+
+C<cx_pushblock()> now saves C<PL_savestack_ix> and C<PL_tmps_floor>, so
+C<pp_enter*> and C<pp_leave*> no longer do
+
+  ENTER; SAVETMPS; ....; LEAVE
+
+=item *
+
+C<cx_popblock()> now also restores C<PL_curpm>.
+
+=item *
+
+In C<dounwind()> for every context type, the current savestack frame is
+now processed before each context is popped; formerly this was only done
+for sub-like context frames. This action has been removed from
+C<cx_popsub()> and placed into its own macro, C<CX_LEAVE_SCOPE(cx)>, which
+must be called before C<cx_popsub()> etc.
+
+C<dounwind()> now also does a C<cx_popblock()> on the last popped frame
+(formerly it only did the C<cx_popsub()> etc. actions on each frame).
+
+=item *
+
+The temps stack is now freed on scope exit; previously, temps created
+during the last statement of a block wouldn't be freed until the next
+C<nextstate> following the block (apart from an existing hack that did
+this for recursive subs in scalar context); and in something like
+C<f(g())>, the temps created by the last statement in C<g()> would
+formerly not be freed until the statement following the return from
+C<f()>.
+
+=item *
+
+Most values that were saved on the savestack on scope entry are now
+saved in suitable new fields in the context struct, and saved and
+restored directly by C<cx_pushfoo()> and C<cx_popfoo()>, which is much
+faster.
+
+=item *
+
+Various context struct fields have been added, removed or modified.
+
+=item *
+
+The handling of C<@_> in C<cx_pushsub()> and C<cx_popsub()> has been
+considerably tidied up, including removing the C<argarray> field from the
+context struct, and extracting out some common (but rarely used) code into
+a separate function, C<clear_defarray()>. Also, useful subsets of
+C<cx_popsub()> which had been unrolled in places like C<pp_goto> have been
+gathered into the new functions C<cx_popsub_args()> and
+C<cx_popsub_common()>.
+
+=item *
+
+C<pp_leavesub> and C<pp_leavesublv> now use the same function as the rest
+of the C<pp_leave*>'s to process return args.
+
+=item *
+
+C<CXp_FOR_PAD> and C<CXp_FOR_GV> flags have been added, and
+C<CXt_LOOP_FOR> has been split into C<CXt_LOOP_LIST>, C<CXt_LOOP_ARY>.
+
+=item *
+
+Some variables formerly declared by C<dMULTICALL> (but not documented) have
+been removed.
+
+=back
+
+=item *
+
 The obscure C<PL_timesbuf> variable, effectively a vestige of Perl 1, has
 been removed. It was documented as deprecated in Perl 5.20, with a statement
 that it would be removed early in the 5.21.x series; that has now finally
@@ -1217,6 +1430,89 @@ C<GvASSIGN_GENERATION> and C<GvASSIGN_GENERATION_set> have been removed.
 
 =item *
 
+Line numbers larger than 2**31-1 but less than 2**32 are no longer
+returned by caller() as negative numbers.  [perl #126991]
+
+=item *
+
+C<< unless ( I<assignment> ) >> now properly warns when syntax
+warnings are enabled.  [perl #127122]
+
+=item *
+
+Setting an C<ISA> glob to an array reference now properly adds
+C<isaelem> magic to any existing elements.  Previously modifying such
+an element would not update the ISA cache, so method calls would call
+the wrong function.  Perl would also crash if the C<ISA> glob was
+destroyed, since new code added in 5.23.7 would try to release the
+C<isaelem> magic from the elements.  [perl #127351]
+
+=item *
+
+If a here-doc was found while parsing another operator, the parser had
+already read end of file, and the here-doc was not terminated, perl
+could produce an assertion or a segmentation fault.  This now reliably
+complains about the unterminated here-doc.  [perl #125540]
+
+=item *
+
+untie() would sometimes return the last value returned by the UNTIE()
+handler as well as it's normal value, messing up the stack.  [perl
+#126621]
+
+=item *
+
+Fixed an operator precedence problem when C< castflags & 2> is true.
+[perl #127474]
+
+=item *
+
+Caching of DESTROY methods could result in a non-pointer or a
+non-STASH stored in the SvSTASH() slot of a stash, breaking the B
+STASH() method.  The DESTROY method is now cached in the MRO metadata
+for the stash.  [perl #126410]
+
+=item *
+
+The AUTOLOAD method is now called when searching for a DESTROY method,
+and correctly sets C<$AUTOLOAD> too.  [perl #124387]  [perl #127494]
+
+=item *
+
+Avoid parsing beyond the end of the buffer when processing a C<#line>
+directive with no filename.  [perl #127334]
+
+=item *
+
+Perl now raises a warning when a regular expression pattern looks like
+it was supposed to contain a POSIX class, like C<qr/[[:alpha:]]/>, but
+there was some slight defect in its specification which causes it to
+instead be treated as a regular bracketed character class.  An example
+would be missing the second colon in the above like this:
+C<qr/[[:alpha]]/>.  This compiles to match a sequence of two characters.
+The second is C<"]">, and the first is any of: C<"[">, C<":">, C<"a">,
+C<"h">, C<"l">, or C<"p">.   This is unlikely to be the intended
+meaning, and now a warning is raised.  No warning is raised unless the
+specification is very close to one of the 14 legal POSIX classes.  (See
+L<perlrecharclass/POSIX Character Classes>.)
+[perl #8904]
+
+=item *
+
+Certain regex patterns involving a complemented POSIX class in an
+inverted bracketed character class, and matching something else
+optionally would improperly fail to match.  An example of one that could
+fail is C</qr/_?[^\Wbar]\x{100}/>.  This has been fixed.
+[perl #127537]
+
+=item *
+
+Perl 5.22 added support to the C99 hexadecimal floating point notation,
+but sometimes misparses hex floats. This had been fixed.
+[perl #127183]
+
+=item *
+
 A regression that allowed undeclared barewords in hash keys to work despite
 strictures has been fixed.
 L<[perl #126981]|https://rt.perl.org/Ticket/Display.html?id=126981>