D:\>perl -E"my $x; BEGIN{$x=q/a.*u/}; use re 'debug'; my $str = 'aou'; say $str
=~ /$x/"
Compiling REx "a.*u"
Final program:
   1: EXACT <a> (3)
   3: STAR (5)
   4:   REG_ANY (0)
   5: EXACT <u> (7)
   7: END (0)
anchored "a" at 0..0 floating "u" at 1..9223372036854775807 (checking floating)
minlen 2
Matching REx "a.*u" against "aou"
Intuit: trying to determine minimum start position...
  doing 'check' fbm scan, [1..3] gave 2
  Found floating substr "u" at offset 2 (rx_origin now 0)...
... YADDA YADDA ...