my@A=([.comb]for lines);
for @A.kv -> \i,\l{for l.kv -> \j,\o {o eq"."&&(my$t;
for -1..1 X -1..1 -> \a,\b {try {$t+=@A[a+i][b+j]eq"*"}}
$t&&@A[i][j]=$t)}}
.join.say for @A
Note that non-ascii characters in the above source code will be escaped (such as \x9f).