$ perl -we'use re "debug"; qr/[\s*\W*]/'
Compiling REx `[\s*\W*]'
size 13 Got 108 bytes for offset annotations.
first at 1
   1: ANYOF[\0-/:-@[-\^`{-\377+utf8::IsSpacePerl !utf8::IsWord](13)
  13: END(0)
stclass `ANYOF[\0-/:-@[-\^`{-\377+utf8::IsSpacePerl !utf8::IsWord]' minlen 1
Offsets: [13]
        1[8] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 9[0]
Freeing REx: `"[\\s*\\W*]"'