^^= is not implemented

[pjcj]

This is a bug report for perl from paul@pjcj.net,
generated with the help of perlbug 1.43 running under perl 5.40.2.

---

Description

We now have the high-precedence xor operator ^^

For a long time we have had the ^ operator.

We have ^= but we do not have ^^= and this appears to be an oversight.

Steps to Reproduce

$ perl5.40.2 -e '$x = 1; $x ^^= 2'
syntax error at -e line 1, near "^^="
Execution of -e aborted due to compilation errors.

Expected behavior

The operator should be implemented.

---

Flags

• category=core
• severity=low

---

Perl configuration

Site configuration information for perl 5.40.2:

Configured by root at Mon Apr 14 15:48:30 CEST 2025.

Summary of my perl5 (revision 5 version 40 subversion 2) configuration:
   
  Platform:
    osname=darwin
    osvers=24.4.0
    archname=darwin-2level
    uname='darwin mbp3.pjcj.net 24.4.0 darwin kernel version 24.4.0: wed mar 19 21:17:37 pdt 2025; root:xnu-11417.101.15~1release_arm64_t6031 arm64 arm darwin '
    config_args='-Dprefix=/Users/pjcj/.plenv/versions/dc-dev -de -Dversiononly -Dusedevel -Dman1dir=none -Dman3dir=none -A'eval:scriptdir=/Users/pjcj/.plenv/versions/dc-dev/bin''
    hint=recommended
    useposix=true
    d_sigaction=define
    useithreads=undef
    usemultiplicity=undef
    use64bitint=define
    use64bitall=define
    uselongdouble=undef
    usemymalloc=n
    default_inc_excludes_dot=define
  Compiler:
    cc='cc'
    ccflags ='-fno-common -DPERL_DARWIN -mmacosx-version-min=15.4 -DNO_THREAD_SAFE_QUERYLOCALE -DNO_POSIX_2008_LOCALE -fno-strict-aliasing -pipe -fstack-protector-strong'
    optimize='-O3'
    cppflags='-fno-common -DPERL_DARWIN -mmacosx-version-min=15.4 -DNO_THREAD_SAFE_QUERYLOCALE -DNO_POSIX_2008_LOCALE -fno-strict-aliasing -pipe -fstack-protector-strong'
    ccversion=''
    gccversion='Apple LLVM 17.0.0 (clang-1700.0.13.3)'
    gccosandvers=''
    intsize=4
    longsize=8
    ptrsize=8
    doublesize=8
    byteorder=12345678
    doublekind=3
    d_longlong=define
    longlongsize=8
    d_longdbl=define
    longdblsize=8
    longdblkind=0
    ivtype='long'
    ivsize=8
    nvtype='double'
    nvsize=8
    Off_t='off_t'
    lseeksize=8
    alignbytes=8
    prototype=define
  Linker and Libraries:
    ld='cc'
    ldflags =' -mmacosx-version-min=15.4 -fstack-protector-strong'
    libpth=/Library/Developer/CommandLineTools/usr/lib/clang/17/lib /Library/Developer/CommandLineTools/SDKs/MacOSX15.4.sdk/usr/lib /Library/Developer/CommandLineTools/usr/lib /usr/lib
    libs= 
    perllibs=
    libc=
    so=dylib
    useshrplib=false
    libperl=libperl.a
    gnulibc_version=''
  Dynamic Linking:
    dlsrc=dl_dlopen.xs
    dlext=bundle
    d_dlsymun=undef
    ccdlflags=' '
    cccdlflags=' '
    lddlflags=' -mmacosx-version-min=15.4 -bundle -undefined dynamic_lookup -fstack-protector-strong'


---
@INC for perl 5.40.2:
    /Users/pjcj/.plenv/versions/dc-dev/lib/perl5/site_perl/5.40.2/darwin-2level
    /Users/pjcj/.plenv/versions/dc-dev/lib/perl5/site_perl/5.40.2
    /Users/pjcj/.plenv/versions/dc-dev/lib/perl5/5.40.2/darwin-2level
    /Users/pjcj/.plenv/versions/dc-dev/lib/perl5/5.40.2

---
Environment for perl 5.40.2:
    DYLD_LIBRARY_PATH (unset)
    HOME=/Users/pjcj
    LANG=en_US.UTF-8
    LANGUAGE=en_US.UTF-8
    LC_ALL=en_US.UTF-8
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=
    PERLBREW_ROOT=/Users/pjcj/perl5/perlbrew
    PERL_BADLANG (unset)
    SHELL=/opt/homebrew/bin/zsh

[leonerd]

Yeah, oops. Seems I forgot to consider this case when implementing the rest of it.

A bit late to think about it for 5.42 now but I'll work on a fix for 5.43.x

[pjcj]

To be fair, it's not documented to work:

  Assignment Operators
    "=" is the ordinary assignment operator.

    Assignment operators work as in C. That is,

        $x += 2;

    is equivalent to

        $x = $x + 2;

    although without duplicating any side effects that dereferencing the
    lvalue might trigger, such as from tie(). Other assignment operators
    work similarly. The following are recognized:

        **=    +=    *=    &=    &.=    <<=    &&=
               -=    /=    |=    |.=    >>=    ||=
               .=    %=    ^=    ^.=           //=
                     x=

So we'll want to update the docs along with the implementation.

[ap]

@leonerd Please produce a patch ASAP; on that basis we may decide to give it a shot with the smokers and then possibly ship it this cycle. If we see any smoke at all we’re not going to, or depending on the patch for whatever other reason maybe not either; but without a patch we have nothing to assess.