how to get Doxygen to work with Fortran interface statements? - fortran

Question

I am working on free software project CCR, which allows climate and other Earth science users to add additional compression methods to netCDF. See https://github.com/ccr/ccr.
I have a Fortran file, and Doxygen is giving me the following warnings:
/home/ed/noaa/ccr/fsrc/ccr.F90:19: warning: Member nc_def_var_bzip2(ncid, varid, level) (function) of class ccr::nc_def_var_bzip2 is not documented.
/home/ed/noaa/ccr/fsrc/ccr.F90:36: warning: Member nc_def_var_lz4(ncid, varid, level) (function) of class ccr::nc_def_var_lz4 is not documented.
/home/ed/noaa/ccr/fsrc/ccr.F90:27: warning: Member nc_inq_var_bzip2(ncid, varid, bzip2p, levelp) (function) of class ccr::nc_inq_var_bzip2 is not documented.
/home/ed/noaa/ccr/fsrc/ccr.F90:44: warning: Member nc_inq_var_lz4(ncid, varid, lz4p, levelp) (function) of class ccr::nc_inq_var_lz4 is not documented.
But I have documented these functions. The line numbers doxygen is complaining about are part of interface statements:
module ccr
!> Interface to initialization function.
interface
function nc_initialize_ccr() bind(c)
use iso_c_binding
end function nc_initialize_ccr
end interface
!> Interface to C function to set BZIP2 compression.
interface
function nc_def_var_bzip2(ncid, varid, level) bind(c)
use iso_c_binding
integer(C_INT), value :: ncid, varid, level
end function nc_def_var_bzip2
end interface
!> Interface to C function to inquire about BZIP2 compression.
interface
function nc_inq_var_bzip2(ncid, varid, bzip2p, levelp) bind(c)
use iso_c_binding
integer(C_INT), value :: ncid, varid
integer(C_INT), intent(inout):: bzip2p, levelp
end function nc_inq_var_bzip2
end interface
!> Interface to C function to set LZ4 compression.
interface
function nc_def_var_lz4(ncid, varid, level) bind(c)
use iso_c_binding
integer(C_INT), value :: ncid, varid, level
end function nc_def_var_lz4
end interface
!> Interface to C function to inquire about LZ4 compression.
interface
function nc_inq_var_lz4(ncid, varid, lz4p, levelp) bind(c)
use iso_c_binding
integer(C_INT), value :: ncid, varid
integer(C_INT), intent(inout):: lz4p, levelp
end function nc_inq_var_lz4
end interface
How do I get Doxygen to see the documentation of the interfaces?

Answer 1

The answer is to use the #fn tag, and specify the entire function signature, after module_name::fn_name::. Here's an example from another project:
interface
!> #fn bacio_module::baciol::baciol(mode, start, newpos, size, no, nactual, fdes, fname, datary)
!> Do a bacio operation.
!>
!> #param mode
!> #param start
!> #param newpos
!> #param size
!> #param no
!> #param nactual
!> #param fdes
!> #param fname
!> #param datary
!>
!> #author Ed Hartnett #date 21-10-18
integer function baciol(mode, start, newpos, size, no, nactual, &
fdes, fname, datary) bind(C)
use, intrinsic :: iso_c_binding
integer(c_int), value, intent(in) :: mode
integer(c_long), value, intent(in) :: start, newpos
integer(c_int), value, intent(in) :: size
integer(c_long), value, intent(in) :: no
integer(c_long), intent(inout) :: nactual
integer(c_int), intent(inout) :: fdes
character(kind=C_char), intent(in) :: fname(*)
character(kind=C_char), intent(in) :: datary(*)
end function baciol
end interface