Inspired by ysth's excellent Re: Automatically add all defined functions to your @EXPORT, I'm reminded that as of perlsub 
Subroutines whose names are in all upper case are reserved to the Perl
core, as are modules whose names are in all lower case.

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OTOH it is customary to use constant.pm like thus (from constant.pm's own documentation): 
SYNOPSIS
           use constant PI    => 4 * atan2(1, 1);
           use constant DEBUG => 0;

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Now, it has never happened to me, but I wonder: any risk of conflicts here?

While it is reasonable to assume that the casual programmer has at least heard about AUTOLOAD, it is much less so that he also know about, say, CLONE and that is not too much of an exotic name for a constant, IMHO.

In reply to All uppercase subs by blazar

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