This is not an answer to your question, but rather a related observation. Here's the relevant section of the docs for do (my emphasis):

• do EXPR

  Uses the value of EXPR as a filename and executes the contents of the file as a Perl script. Its primary use is to include subroutines from a Perl subroutine library.

       do 'stat.pl';
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  is just like

       eval `cat stat.pl`;
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  except that it’s more efficient and concise, keeps track of the current filename for error messages, searches the @INC libraries, and updates %INC if the file is found. … It also differs in that code evaluated with "do FILENAME" cannot see lexi­cals in the enclosing scope; "eval STRING" does.

# y.pl
use strict;
use warnings;
use diagnostics;

do 'x.pl';
print 'do: ', +( $@ ? $@ : 'ok' ), "\n";

eval `cat x.pl`;
print 'eval: ', +( $@ ? $@ : 'ok' ), "\n";
__END__
do: ok
Variable "$x" is not imported at (eval 2) line 1 (#1)
    (F) While "use strict" in effect, you referred to a global variabl
+e that
    you apparently thought was imported from another module, because
    something else of the same name (usually a subroutine) is exported
+ by
    that module.  It usually means you put the wrong funny character o
+n the
    front of your variable.
    
eval: Global symbol "$x" requires explicit package name at (eval 2) li
+ne 1.
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So you'll need to use eval instead of do if you want strictures, but you'll have to check $@ yourself after the eval.