#source: group10.s
#ld: -r -T group.ld
#readelf: -Sg --wide
#...
group section \[[ 0-9]+\] `\.group' \[foo_group\] contains . sections:
\[Index\] Name
\[[ 0-9]+\] \.text.*
\[[ 0-9]+\] \.rodata\.str.*
\[[ 0-9]+\] \.data.*
\[[ 0-9]+\] \.keepme.*