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[perl #132586] in-place sort retains tiedness

From:
Zefram
Date:
December 15, 2017 10:11
Subject:
[perl #132586] in-place sort retains tiedness
Message ID:
rt-4.0.24-7817-1513332707-1462.132586-75-0@perl.org
# New Ticket Created by  Zefram 
# Please include the string:  [perl #132586]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org/Ticket/Display.html?id=132586 >



This is a bug report for perl from zefram@fysh.org,
generated with the help of perlbug 1.41 running under perl 5.27.6.


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

Suppose I have an array of which an element is tied.  List assignment
of the array to itself would of course drop the tiedness, by virtue of
copying the tied scalar's value to a fresh, untied scalar.  But if I
assign the result of a sort on the array back to the array, tiedness
remains:

$ perl -lwe 'package T { sub TIESCALAR { bless({}, $_[0]) } sub FETCH { "b" } } @a = qw(a b c); tie $a[1], "T"; print tied($a[1]) // "undef"; @a = sort @a; print tied($a[1]) // "undef"; @a = ((), sort @a); print tied($a[1]) // "undef"'
T=HASH(0x7a8ad0)
T=HASH(0x7a8ad0)
undef

Obviously this is yet another fault of the in-place sort optimisation,
similar to the recently-rectified treatment of weak references.

[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags:
    category=core
    severity=low
---
Site configuration information for perl 5.27.6:

Configured by zefram at Tue Nov 21 05:42:59 GMT 2017.

Summary of my perl5 (revision 5 version 27 subversion 6) configuration:
   
  Platform:
    osname=linux
    osvers=3.16.0-4-amd64
    archname=x86_64-linux-thread-multi
    uname='linux barba.rous.org 3.16.0-4-amd64 #1 smp debian 3.16.43-2+deb8u2 (2017-06-26) x86_64 gnulinux '
    config_args='-des -Dprefix=/home/zefram/usr/perl/perl_install/perl-5.27.6-i64-f52 -Duselargefiles -Dusethreads -Uafs -Ud_csh -Uusesfio -Uusenm -Duseshrplib -Dusedevel -Uversiononly -Ui_db'
    hint=recommended
    useposix=true
    d_sigaction=define
    useithreads=define
    usemultiplicity=define
    use64bitint=define
    use64bitall=define
    uselongdouble=undef
    usemymalloc=n
    default_inc_excludes_dot=define
    bincompat5005=undef
  Compiler:
    cc='cc'
    ccflags ='-D_REENTRANT -D_GNU_SOURCE -fwrapv -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -D_FORTIFY_SOURCE=2'
    optimize='-O2'
    cppflags='-D_REENTRANT -D_GNU_SOURCE -fwrapv -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include'
    ccversion=''
    gccversion='4.9.2'
    gccosandvers=''
    intsize=4
    longsize=8
    ptrsize=8
    doublesize=8
    byteorder=12345678
    doublekind=3
    d_longlong=define
    longlongsize=8
    d_longdbl=define
    longdblsize=16
    longdblkind=3
    ivtype='long'
    ivsize=8
    nvtype='double'
    nvsize=8
    Off_t='off_t'
    lseeksize=8
    alignbytes=8
    prototype=define
  Linker and Libraries:
    ld='cc'
    ldflags =' -fstack-protector-strong -L/usr/local/lib'
    libpth=/usr/local/lib /usr/lib/gcc/x86_64-linux-gnu/4.9/include-fixed /usr/include/x86_64-linux-gnu /usr/lib /lib/x86_64-linux-gnu /lib/../lib /usr/lib/x86_64-linux-gnu /usr/lib/../lib /lib
    libs=-lpthread -lnsl -ldb -ldl -lm -lcrypt -lutil -lc
    perllibs=-lpthread -lnsl -ldl -lm -lcrypt -lutil -lc
    libc=libc-2.19.so
    so=so
    useshrplib=true
    libperl=libperl.so
    gnulibc_version='2.19'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs
    dlext=so
    d_dlsymun=undef
    ccdlflags='-Wl,-E -Wl,-rpath,/home/zefram/usr/perl/perl_install/perl-5.27.6-i64-f52/lib/5.27.6/x86_64-linux-thread-multi/CORE'
    cccdlflags='-fPIC'
    lddlflags='-shared -O2 -L/usr/local/lib -fstack-protector-strong'


---
@INC for perl 5.27.6:
    /home/zefram/usr/perl/perl_install/perl-5.27.6-i64-f52/lib/site_perl/5.27.6/x86_64-linux-thread-multi
    /home/zefram/usr/perl/perl_install/perl-5.27.6-i64-f52/lib/site_perl/5.27.6
    /home/zefram/usr/perl/perl_install/perl-5.27.6-i64-f52/lib/5.27.6/x86_64-linux-thread-multi
    /home/zefram/usr/perl/perl_install/perl-5.27.6-i64-f52/lib/5.27.6

---
Environment for perl 5.27.6:
    HOME=/home/zefram
    LANG (unset)
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/home/zefram/usr/perl/perl_install/perl-5.27.6-i64-f52/bin:/home/zefram/usr/perl/util:/home/zefram/pub/x86_64-unknown-linux-gnu/bin:/home/zefram/pub/common/bin:/usr/bin:/bin:/usr/local/bin:/usr/games
    PERLDOC=-oman
    PERL_BADLANG (unset)
    SHELL=/usr/bin/zsh




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