No, that doesn't help. I'm sure some other Fortran programmers using CB must have encountered this issue.
To check how gfortran behaves outside of CB, I compiled a trivial test program:
program main
integer :: i, j, k
k = 0
do i = 1,10
do j = 1,3
k = k+10
enddo
enddo
write(*,*) 'k: ',k
end program
where the indentation on lines 5,6,7 uses tabs.
Compiled with
>gfortran -c test.f90
there are no warnings.
With
>gfortran -c -Wtabs test.f90
there are 3 tabs warnings
With
>gfortran -c -Wno-tabs test.f90
there are no warnings.
Using -Wtabs, -Wno-tabs or no compiler option in CB gives tabs warnings. I have not been able to find any combination of compiler switches that turns these warnings off. It is frustrating.