certain functions (e.g., lc) change their behavior depending on how the flag is set.

Yes, this is indeed the fly in the ointment. As far as I know such cases are documented - and in this case at least the documentation describes mechanisms that force it to behave one way or another independent of the UTF8 flag (eg use bytes versus use feature 'unicode_strings').

Those aspects of Perl that requires you to know the state of the UTF8 flag are collectively known as "the Unicode bug", and there is more detail in a section devoted to this in perlunicode.

In reply to Re^3: Seeking Perl docs about how UTF8 flag propagates by hv
in thread Seeking Perl docs about how UTF8 flag propagates by raygun

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.