Fix linter issues

app/argument.f90

@@ -193,7 +193,7 @@ recursive subroutine get_response_file(self, resp, stat)
       call push_back(self, arg)
    end do
    close(unit, iostat=stat)
-   if (info /= 0) then
+   if (stat == 0 .and. info /= 0) then
       stat = merge(0, info, is_iostat_end(info))
    end if
 end subroutine get_response_file
@@ -207,7 +207,7 @@ subroutine getline(unit, line, iostat, iomsg)
    !> Status of operation
    integer, intent(out) :: iostat
    !> Error message
-   character(len=:), allocatable, optional :: iomsg
+   character(len=:), allocatable, optional, intent(out) :: iomsg
 
    integer, parameter :: bufsize = 512
    character(len=bufsize) :: buffer, msg

app/cli.f90

@@ -104,7 +104,7 @@ subroutine get_argument_as_real(arg, val, error)
    !> Real value
    real(wp), intent(out) :: val
    !> Error handling
-   type(error_type), allocatable :: error
+   type(error_type), allocatable, intent(out) :: error
 
    integer :: stat
 
@@ -124,7 +124,7 @@ end subroutine get_argument_as_real
 subroutine get_argument_as_integer_list(arg, vals, error)
    character(len=:), intent(in), allocatable :: arg
    integer, allocatable, intent(out) :: vals(:)
-   type(error_type), allocatable :: error
+   type(error_type), allocatable, intent(out) :: error
 
    integer :: pos, stat
    integer, allocatable :: tmp(:)

app/toml.f90

@@ -302,6 +302,8 @@ subroutine get(self, param, method, damping)
             call new_cso_damping(tmp, record%param)
             call move_alloc(tmp, param)
          end block
+      case default
+         continue
       end select
    end associate
 end subroutine get

doc/tutorial/first-steps-fortran/src/scan.f90

@@ -37,7 +37,7 @@ end subroutine get_dispersion_for_reaction
 subroutine scan_param_for_reaction(error, reaction, method, dft_energy)
    use dftd3, only : d3_param
    use mctc_env, only : error_type, fatal_error
-   type(error_type), allocatable :: error
+   type(error_type), allocatable, intent(out) :: error
    type(reaction_type), intent(in) :: reaction
    character(*), intent(in) :: method
    real(wp), intent(in), optional :: dft_energy

fpm.toml

@@ -36,14 +36,6 @@ main = "api-test.c"
 ignore = [
   "C002",  # interface without implicit none
   "C003",  # implicit none(external)
-  "C011",  # no default in select case
-  "C061",  # missing intent attribute
-  "C071",  # assumed size
-  "C072",  # assumed size character intent
-  "C081",  # implicit save
-  "C121",  # use without explicit only
-  "C122",  # intrinsic missing for internal modules
-  "C131",  # default module accessibility
-  "C181",  # iostat not checked
 ]
+per-file-ignores."src/dftd3/api.f90" = ["C071", "C072"]
 line-length = 132

src/dftd3/api.f90

@@ -20,6 +20,8 @@
 !>{!./include/s-dftd3.h!}
 !>```
 module dftd3_api
+   use, intrinsic :: iso_c_binding, only : c_associated, c_bool, c_char, c_double, &
+      & c_f_pointer, c_int, c_loc, c_null_char, c_null_ptr, c_ptr
    use dftd3_cutoff, only : realspace_cutoff
    use dftd3_damping, only : damping_param
    use dftd3_damping_cso, only : cso_damping_param, new_cso_damping
@@ -37,7 +39,6 @@ module dftd3_api
       & get_cso_damping, get_z_damping
    use dftd3_utils, only : wrap_to_central_cell
    use dftd3_version, only : get_dftd3_version
-   use iso_c_binding
    use mctc_env, only : wp, error_type, fatal_error
    use mctc_io_structure, only : structure_type, new
    implicit none

src/dftd3/citation.f90

@@ -708,6 +708,8 @@ pure function get_citation(doi) result(citation)
          pages="2506.14665", &
          year="2025" &
       )
+   case default
+      continue
    end select
 end function get_citation
 

src/dftd3/cutoff.f90

@@ -17,6 +17,7 @@
 module dftd3_cutoff
    use mctc_env, only : wp
    implicit none
+   private
 
    public :: realspace_cutoff, get_lattice_points, smooth_cutoff
 

src/dftd3/damping.f90

@@ -18,6 +18,7 @@ module dftd3_damping
    use mctc_env, only : wp
    use mctc_io, only : structure_type
    implicit none
+   private
 
    public :: damping_param, dispersion_interface
 

src/dftd3/damping/atm.f90

@@ -19,6 +19,7 @@ module dftd3_damping_atm
    use mctc_env, only : wp
    use mctc_io, only : structure_type
    implicit none
+   private
 
    public :: get_atm_dispersion, get_atm_pairwise_dispersion
 

src/dftd3/damping/cso.f90

@@ -22,6 +22,7 @@ module dftd3_damping_cso
    use mctc_env, only : wp
    use mctc_io, only : structure_type
    implicit none
+   private
 
    public :: cso_damping_param, new_cso_damping
 

src/dftd3/damping/mzero.f90

@@ -22,6 +22,7 @@ module dftd3_damping_mzero
    use mctc_env, only : wp
    use mctc_io, only : structure_type
    implicit none
+   private
 
    public :: mzero_damping_param, new_mzero_damping
 

src/dftd3/damping/optimizedpower.f90

@@ -22,6 +22,7 @@ module dftd3_damping_optimizedpower
    use mctc_env, only : wp
    use mctc_io, only : structure_type
    implicit none
+   private
 
    public :: optimizedpower_damping_param, new_optimizedpower_damping
 

src/dftd3/damping/rational.f90

@@ -22,6 +22,7 @@ module dftd3_damping_rational
    use mctc_env, only : wp
    use mctc_io, only : structure_type
    implicit none
+   private
 
    public :: rational_damping_param, new_rational_damping
 

src/dftd3/damping/z.f90

@@ -22,6 +22,7 @@ module dftd3_damping_z
    use mctc_env, only : wp
    use mctc_io, only : structure_type
    implicit none
+   private
 
    public :: z_damping_param, new_z_damping
 

src/dftd3/damping/zero.f90

@@ -22,6 +22,7 @@ module dftd3_damping_zero
    use mctc_env, only : wp
    use mctc_io, only : structure_type
    implicit none
+   private
 
    public :: zero_damping_param, new_zero_damping
 

src/dftd3/gcp.f90

@@ -485,9 +485,15 @@ end subroutine srb_deriv
 !* Inspired by mopac7.0
 !******************************************************************************
 subroutine ssovl(r, iat, jat, iz, xza, xzb, ovl)
+   real(wp), intent(in) :: r
+   integer, intent(in) :: iat, jat
+   integer, intent(in) :: iz(:)
+   real(wp), intent(in) :: xza, xzb
+   real(wp), intent(out) :: ovl
+
    integer :: ii, shell(72)
    logical :: debug
-   real(wp) :: za, zb, R, ovl, ax, bx, norm, R05
+   real(wp) :: za, zb, ax, bx, norm, R05
    integer :: na, nb
    real(wp) :: xx
    data shell/                 &
@@ -501,8 +507,6 @@ subroutine ssovl(r, iat, jat, iz, xza, xzb, ovl)
    !         k-rn , no f-elements
             54*3/
    ! ...
-   real(wp) :: xza, xzb
-   integer :: iat, jat, iz(*)
 
    za = xza
    zb = xzb
@@ -580,6 +584,8 @@ subroutine ssovl(r, iat, jat, iz, xza, xzb, ovl)
          norm = sqrt((ZA*ZB*R*R)**7)/480.0d0
          ovl = norm*(A6(ax)*Bint(bx, 0)-3.0d0*(A4(ax)*Bint(bx, 2) &
             & -A2(ax)*Bint(bx, 4))-A0(ax)*Bint(bx, 6))/3.0_wp
+      case default
+         error stop "invalid shell combination in ssovl"
       end select
    else ! different elements
       select case (ii)
@@ -634,6 +640,8 @@ subroutine ssovl(r, iat, jat, iz, xza, xzb, ovl)
       case(9) ! <3s|3>
          norm = sqrt((ZA*ZB*R*R)**7)/1440.0d0
          ovl = norm*(A6(ax)*B0(bx)-3.0d0*(A4(ax)*B2(bx)-A2(ax)*B4(bx))-A0(ax)*B6(bx))
+      case default
+         error stop "invalid shell combination in ssovl"
       end select
    end if
 end subroutine ssovl
@@ -851,7 +859,8 @@ end function bint
 ! faculty function
 integer(wp) function fact(N)
 implicit none
-integer :: j, n
+integer, intent(in) :: n
+integer :: j
 fact = 1
 do j = 2, n
   fact = fact*j
@@ -870,9 +879,15 @@ subroutine gsovl(r, iat, jat, iz, xza, xzb, g)
    ! za  = slater exponent atom A
    ! zb  = slater exponent atom B
    ! R   = distance between atom A and B
+   real(wp), intent(in) :: r
+   integer, intent(in) :: iat, jat
+   integer, intent(in) :: iz(:)
+   real(wp), intent(in) :: xza, xzb
+   real(wp), intent(out) :: g
+
    integer :: ii, shell(72)
    logical :: debug
-   real(wp) :: ax, bx, R05, za, zb, R
+   real(wp) :: ax, bx, R05, za, zb
    integer :: na, nb
    data shell/                 &
    !          h, he
@@ -885,11 +900,9 @@ subroutine gsovl(r, iat, jat, iz, xza, xzb, g)
    !         k-rn , no f-elements
             54*3/
    ! ...
-   real(wp) :: g, Fa, Fb
+   real(wp) :: Fa, Fb
    !--------------------- set exponents ---------------------------------------
-   real(wp) :: xza, xzb
    real(wp) :: xx
-   integer :: iat, jat, iz(*)
    logical :: lsame
 
    za = xza
@@ -952,6 +965,8 @@ subroutine gsovl(r, iat, jat, iz, xza, xzb, g)
          end if
       case(9)
          call g3s3s(za, zb, Fa, Fb, R, g, lsame)
+      case default
+         error stop "invalid shell combination in gsovl"
       end select
    else ! different elements
       lsame = .false.
@@ -989,6 +1004,8 @@ subroutine gsovl(r, iat, jat, iz, xza, xzb, g)
          end if
       case(9) ! <3s|3>
          call g3s3s(za, zb, Fa, Fb, R, g, lsame)
+      case default
+         error stop "invalid shell combination in gsovl"
       end select
    end if
 
@@ -1005,9 +1022,10 @@ subroutine g1s1s(za, zb, Fa, Fb, R, g, sameElement)
    ! derivative of explicit integral expression
    ! using maple
    implicit real(wp) (t)
-   real(wp) :: za, zb, Fa, Fb
-   real(wp) :: g, R
-   logical :: sameElement
+   real(wp), intent(in) :: za, zb, Fa, Fb
+   real(wp), intent(in) :: R
+   real(wp), intent(out) :: g
+   logical, intent(in) :: sameElement
 
    if(sameElement) then
       t1 = za ** 2
@@ -1059,10 +1077,13 @@ subroutine g2s1s(za, zb, Fa, Fb, R, g, switch, lsame)
    ! derivative of explicit integral expression
    ! using maple
    implicit real(wp) (t)
-   real(wp) :: za, zb, Fa, Fb
-   real(wp) :: g, R, norm
-   logical :: switch
-   logical :: lsame
+   real(wp), intent(in) :: za, zb, Fa
+   real(wp), intent(inout) :: Fb
+   real(wp), intent(in) :: R
+   real(wp), intent(out) :: g
+   real(wp) :: norm
+   logical, intent(in) :: switch
+   logical, intent(in) :: lsame
    norm = (1d0/24d0)*sqrt(za**3*zb**5*3d0)
 
    if(switch) then
@@ -1123,9 +1144,11 @@ subroutine g2s2s(za, zb, Fa, Fb, R, g, SameElement)
    ! derivative of explicit integral expression
    ! using maple
    implicit real(wp) (t)
-   real(wp) :: za, zb, Fa, Fb
-   real(wp) :: g, R, norm
-   logical :: SameElement
+   real(wp), intent(in) :: za, zb, Fa, Fb
+   real(wp), intent(in) :: R
+   real(wp), intent(out) :: g
+   real(wp) :: norm
+   logical, intent(in) :: SameElement
 
    norm = 1d0/(16d0*3d0)*SQRT((ZA*ZB)**5)
 
@@ -1191,10 +1214,13 @@ subroutine g1s3s(za, zb, Fa, Fb, R, g, switch, lsame)
    ! derivative of explicit integral expression
    ! using maple
    implicit real(wp) (t)
-   real(wp) :: za, zb, Fa, Fb
-   real(wp) :: g, R, norm
-   logical :: switch
-   logical :: lsame
+   real(wp), intent(in) :: za, zb, Fa
+   real(wp), intent(inout) :: Fb
+   real(wp), intent(in) :: R
+   real(wp), intent(out) :: g
+   real(wp) :: norm
+   logical, intent(in) :: switch
+   logical, intent(in) :: lsame
 
    if(switch) Fb = -Fb
 
@@ -1263,10 +1289,13 @@ subroutine g2s3s(za, zb, Fa, Fb, R, g, switch, lsame)
    ! derivative of explicit integral expression
    ! using maple
    implicit real(wp) (t)
-   real(wp) :: za, zb, Fa, Fb
-   real(wp) :: g, R, norm
-   logical :: switch
-   logical :: lsame
+   real(wp), intent(in) :: za, zb, Fa
+   real(wp), intent(inout) :: Fb
+   real(wp), intent(in) :: R
+   real(wp), intent(out) :: g
+   real(wp) :: norm
+   logical, intent(in) :: switch
+   logical, intent(in) :: lsame
    norm = sqrt((za**5)*(zb**7)/7.5_wp)/96.0d0
 
    if(switch) Fb = -Fb
@@ -1351,9 +1380,11 @@ subroutine g3s3s(za, zb, Fa, Fb, R, g, SameElement)
    ! derivative of explicit integral expression
    ! using maple
    implicit real(wp) (t)
-   real(wp) :: za, zb, Fa, Fb
-   real(wp) :: g, R, norm
-   logical :: SameElement
+   real(wp), intent(in) :: za, zb, Fa, Fb
+   real(wp), intent(in) :: R
+   real(wp), intent(out) :: g
+   real(wp) :: norm
+   logical, intent(in) :: SameElement
 
    norm = sqrt((ZA*ZB)**7)/1440.0d0
 

src/dftd3/gcp/param.f90

@@ -570,6 +570,8 @@ subroutine get_gcp_param(param, mol, method, basis, eta)
          eta_ = 1.4022_wp
          param%alpha = 0.8055_wp
          param%beta = 1.3000_wp
+      case default
+         continue
       end select
 
    case(p_sv_p_bas)
@@ -906,6 +908,8 @@ subroutine get_gcp_param(param, mol, method, basis, eta)
          param%damp = .true.
       end if
 
+   case default
+      continue
    end select
    if (allocated(nbas)) then
       param%xv = nbas - 0.5_wp * nel

src/dftd3/model.f90

@@ -15,9 +15,9 @@
 ! along with s-dftd3.  If not, see <https://www.gnu.org/licenses/>.
 
 module dftd3_model
+   use, intrinsic :: ieee_arithmetic, only : ieee_is_nan
    use dftd3_data, only : get_r4r2_val, get_vdw_rad
-   use dftd3_reference
-   use ieee_arithmetic, only : ieee_is_nan
+   use dftd3_reference, only : number_of_references, reference_cn, get_c6, init_reference_c6
    use mctc_data, only : get_covalent_rad
    use mctc_env, only : wp
    use mctc_io, only : structure_type