I checked with B::Deparse and B::Concise and the variable name is clearly visible i.e not optimized away:

> perl -MO=Deparse,-q
use warnings;
my (%a, %b, $c);
my $x = "$a{'foo'} $b{'bar'} $c"
__END__
use warnings;
my(%a, %b, $c);
my $x = $a{'foo'} . ' ' . $b{'bar'} . ' ' . $c;
- syntax OK

[download]

-q reveals the mentioned optimization of string-interpolations, but the variable name is not affected.

<Reveal this spoiler or all in this thread>

I thought this is only a negligible bug, such that after fixing $a{foo} the following $b{bar} would be visible, but that's unfortunately not the case:

>  perl -w 
my (%a, %b, $c);  
$a{foo}="FIXED";
my $x = "$a{'foo'} $b{'bar'} $c";
__END__
Use of uninitialized value in concatenation (.) or string at - line 3.
Use of uninitialized value $c in concatenation (.) or string at - line
+ 3.

[download]

Cheers Rolf

( addicted to the Perl Programming Language)

In reply to Re^2: Variable name missing in warning by LanX
in thread Variable name missing in warning by bogbert

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.