#  Need perl to be built with DEBUGGING
perl -Dr -e '$p = qr{\Q ++ \E} ; $q = qr{\Q ++ \E}x ; $r = qr{\Q++\E}'
Compiling REx `\ \+\+\ '
size 3 Got 28 bytes for offset annotations.
first at 1
rarest char + at 1
   1: EXACT < ++ >(3)
   3: END(0)
anchored " ++ " at 0 (checking anchored isall) minlen 4
Offsets: [3]
        1[8] 0[0] 9[0]
Compiling REx `\ \+\+\ '
size 3 Got 28 bytes for offset annotations.
first at 1
rarest char + at 1
   1: EXACT < ++ >(3)
   3: END(0)
anchored " ++ " at 0 (checking anchored isall) minlen 4
Offsets: [3]
        1[8] 0[0] 9[0]
Compiling REx `\+\+'
size 3 Got 28 bytes for offset annotations.
first at 1
rarest char + at 0
   1: EXACT <++>(3)
   3: END(0)
anchored "++" at 0 (checking anchored isall) minlen 2
Offsets: [3]
        1[4] 0[0] 5[0]
Omitting $` $& $' support.

EXECUTING...

Freeing REx: `"\\ \\+\\+\\ "'
Freeing REx: `"\\ \\+\\+\\ "'
Freeing REx: `"\\+\\+"'