% perl
use strict;
$x = 1; 
print $x,$/;
^D
Global symbol "$x" requires explicit package name at - line 2.
Global symbol "$x" requires explicit package name at - line 3.
Execution of - aborted due to compilation errors.

% perl
eval 'use strict' if 1;
$x = 1;
print $x,$/;
^D
1