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[perl #117341] av_undef's POD is confusing

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From:
bulk88
Date:
March 25, 2013 15:56
Subject:
[perl #117341] av_undef's POD is confusing
Message ID:
rt-3.6.HEAD-28177-1364226975-1580.117341-75-0@perl.org
# New Ticket Created by  bulk88 
# Please include the string:  [perl #117341]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org:443/rt3/Ticket/Display.html?id=117341 >


This is a bug report for perl from bulk88@hotmail.com,
generated with the help of perlbug 1.39 running under perl 5.17.7.


-----------------------------------------------------------------
[Please describe your issue here]

av_undef's POD last got worked on in 
http://perl5.git.perl.org/perl.git/commit/8b9a1153f14d44cea2fcef118be9de0eea3dcaca?f=av.c 
as part of Perl #107440 and 
http://perl5.git.perl.org/perl.git/commit/60edcf09a5cb026822f99270a4bfbe3149cfbb52?f=av.c 
. Its current POD is
____________________________________________________________________
/*
=for apidoc av_undef

Undefines the array.  Frees the memory used by the av to store its list of
scalars.  If any destructors are triggered as a result, the av itself may
be freed.

=cut
*/
____________________________________________________________________

av_clear's POD says "Perl equivalent: C<@myarray = ();>." Wouldn't 
av_undef be the same thing except av_undef frees more memory than an 
av_clear would? So, what is the script level difference between av_clear 
and av_undef? none?

Another problem is, " Frees the memory used by the av to store its list 
of scalars.  If any destructors are triggered as a result, the av itself 
may be freed." implies that av_undef can be used instead of calling 
SvREFCNT_dec/sv_2mortal. Someone else did get confused by that sentence 
and did think av_undef frees an AV (SV) head. I can't think of a better 
wording so I offer no patch. I didn't fully understand  #107440.  

Maybe " If any destructors are triggered as a result, the av itself may 
be freed." can be replaced with "If the only refcount owner of the AV *, 
is at the end of a chain of (circular) references that wind up owning 
the only AV * refcount notch, the AV * will be freeded."

[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags:
    category=docs
    severity=medium
---
Site configuration information for perl 5.17.7:

Configured by Owner at Sun Dec 16 13:25:34 2012.

Summary of my perl5 (revision 5 version 17 subversion 7 patch blead 
2012-12-06.16:42:20 93a641ae382638ffd1980378be4810244d04f4b0 
v5.17.6-186-g93a641a) configuration:
  Snapshot of: 93a641ae382638ffd1980378be4810244d04f4b0
  Platform:
    osname=MSWin32, osvers=5.1, archname=MSWin32-x86-multi-thread
    uname=''
    config_args='undef'
    hint=recommended, useposix=true, d_sigaction=undef
    useithreads=define, usemultiplicity=define
    useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
    use64bitint=undef, use64bitall=undef, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='cl', ccflags ='-nologo -GF -W3 -MD -Zi -DNDEBUG -O1 -GL -G7 
-DWIN32 -D_CONSOLE -DNO_STRICT  -DPERL_TEXTMODE_SCRIPTS 
-DPERL_IMPLICIT_CONTEXT -DPERL_IMPLICIT_SYS -DUSE_PERLIO 
-D_USE_32BIT_TIME_T',
    optimize='-MD -Zi -DNDEBUG -O1 -GL -G7',
    cppflags='-DWIN32'
    ccversion='13.10.6030', gccversion='', gccosandvers=''
    intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
    d_longlong=undef, longlongsize=8, d_longdbl=define, longdblsize=8
    ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='__int64', 
lseeksize=8
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='link', ldflags ='-nologo -nodefaultlib -debug -opt:ref,icf 
-ltcg  -libpath:"c:\perl517\lib\CORE"  -machine:x86'
    libpth="C:\Program Files\Microsoft Visual Studio .NET 2003\VC7\lib"
    libs=oldnames.lib kernel32.lib user32.lib gdi32.lib winspool.lib  
comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib  
netapi32.lib uuid.lib ws2_32.lib mpr.lib winmm.lib  version.lib 
odbc32.lib odbccp32.lib comctl32.lib msvcrt.lib
    perllibs=oldnames.lib kernel32.lib user32.lib gdi32.lib 
winspool.lib  comdlg32.lib advapi32.lib shell32.lib ole32.lib 
oleaut32.lib  netapi32.lib uuid.lib ws2_32.lib mpr.lib winmm.lib  
version.lib odbc32.lib odbccp32.lib comctl32.lib msvcrt.lib
    libc=msvcrt.lib, so=dll, useshrplib=true, libperl=perl517.lib
    gnulibc_version=''
  Dynamic Linking:
    dlsrc=dl_win32.xs, dlext=dll, d_dlsymun=undef, ccdlflags=' '
    cccdlflags=' ', lddlflags='-dll -nologo -nodefaultlib -debug 
-opt:ref,icf -ltcg  -libpath:"c:\perl517\lib\CORE"  -machine:x86'

Locally applied patches:
    

---
@INC for perl 5.17.7:
    C:/perl517/site/lib
    C:/perl517/lib
    .

---
Environment for perl 5.17.7:
    HOME (unset)
    LANG (unset)
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=C:\perl517\bin;C:\Program Files\Microsoft Visual Studio .NET 
2003\Common7\IDE;C:\Program Files\Microsoft Visual Studio .NET 
2003\VC7\BIN;C:\Program Files\Microsoft Visual Studio .NET 
2003\Common7\Tools;C:\Program Files\Microsoft Visual Studio .NET 
2003\Common7\Tools\bin\prerelease;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\system32\wbem;
    PERL_BADLANG (unset)
    SHELL (unset)


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