Running the following program under ActiveState 5.8.9 and Strawberries 5.10/12/14 (all Win32) gives me identical results: 

c:\@Work\Perl>perl -wMstrict -le
"my $x = 0;
 my $y;
 ;;
 sub S :lvalue { if ($x) { $y; } }
 ;;
 S() = 'foo';
 ;;
 print qq{x '$x'  y '$y'};
"
Can't modify logical and (&&) in lvalue subroutine return at -e line 1
+, near "} }"
Execution of -e aborted due to compilation errors.

[download]

Given the experimental nature of  :lvalue trumpeted in the Lvalue subroutines section of perlsub, I would be very reluctant to use it with a complex subroutine. If the Perl compiler can't even figure out the simple example code above, what hope for the vipers' nest of conditionals that is the  _Var() workhorse?

(Somewhere in the back of my mind is something about the compiler sometimes optimizing a statement like
    if ($x) { do_this(); };
to
    $x && do_this();
so this may be part of the problem — but don't quote me on this!
Update: Actually, it's  $y if $x; that is so optimized/compiled, using and not &&. Nevermind...)

In reply to Re^2: weird error message in middle-aged-perl(5.14) by AnomalousMonk
in thread weird error message in middle-aged-perl(5.14) by perl-diddler

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.