f() { return $1; }

[ `f 42; { cat; } <<EOF
$?
EOF
` = 42 ] || echo compound command bad

[ `f 42; (cat) <<EOF
$?
EOF
` = 42 ] || echo subshell bad

long=`printf %08192d 0`

[ `f 42; { cat; } <<EOF
$long.$?
EOF
` = $long.42 ] || echo long compound command bad

[ `f 42; (cat) <<EOF
$long.$?
EOF
` = $long.42 ] || echo long subshell bad