Wrong source type originating from parse_f_source

[ivan-pi]

Description

The function parse_f_source returns the wrong source type for the following module:

module foo
public :: bar
abstract interface
    subroutine bar() bind(c)
    end subroutine
end interface
end module foo

Expected Behaviour

Instead of FPM_UNIT_MODULE (=2) it returns FPM_UNIT_SUBPROGRAM (=4). Removing the bind(c) makes the source parser work correctly.

Version of fpm

Version: 0.8.1, alpha

Platform and Architecture

MacOS

Additional Information

No response

[ivan-pi]

Here is a possible test for the issue:

!> Check parsing of module containing abstract interface with bind(c) attribute
!>   See also https://github.com/fortran-lang/fpm/issues/1073
subroutine test_module_with_abstract_interface_c_binding(error)

    type(error_t), allocatable, intent(out) :: error

    integer :: unit
    character(:), allocatable :: temp_file
    type(srcfile_t), allocatable :: f_source

    allocate(temp_file,source=get_temp_filename())
    open(file=tempfile,newunit=unit)
    write(unit, '(A)') &
    & 'module foo', &
    & 'abstract interface', &
    & '   subroutine bar1()', &
    & '   end subroutine', &
    & '   subroutine bar2() bind(c)', &
    & '   end subroutine', &
    & 'end interface', &
    & 'end module foo'

    close(unit)
    f_source = parse_f_source(temp_file,error)

    if (allocated(error)) return

    if (f_source%unit_type /= FPM_UNIT_MODULE) then
        call test_failed(error,'Wrong unit type detected - expecting FPM_UNIT_MODULE')
        return
    end if
    if (size(f_source%modules_provided) /= 1) then
        call test_failed(error,'Wrong number of modules provided - expecting one')
        return
    end if
    if (size(f_source%modules_used) /= 0) then
        call test_failed(error,'Incorrect number of modules_used - expecting zero')
        return
    end if

    call f_source%test_serialization('srcfile_t: serialization', error)
end subroutine test_module_with_abstract_interface

[ivan-pi]

I think the cause is a clash between how the parser handles C bindings and how it determines if it is in an interface:

fpm/src/fpm_source_parsing.f90

Lines 113 to 115 in da6d1bf

	! Detect exported C-API via bind(C)
	if (.not.inside_interface .and. &
	parse_subsequence(file_lines_lower(i)%s,'bind','(','c')) then

fpm/src/fpm_source_parsing.f90

Lines 155 to 169 in da6d1bf

	! Detect beginning of interface block
	if (index(file_lines_lower(i)%s,'interface') == 1) then
	inside_interface = .true.
	cycle
	end if
	! Detect end of interface block
	if (parse_sequence(file_lines_lower(i)%s,'end','interface')) then
	inside_interface = .false.
	cycle
	end if

Maybe changing the predicate at L156 to

if (index(file_lines_lower(i)%s,'interface') == 1) &
    .or. parse_sequence(file_lines_lower(i)%s,'abstract','interface')) then
   ! ...
end if

would fix the issue.

[ivan-pi]

The problem also occurs when an abstract interface containing a bind(c) procedure is in a program unit. For instance, the following get misclassified as FPM_UNIT_SUBPROGRAM (=4):

program my_program
implicit none
abstract interface
   function cmpfunc(a,b) bind(c)
     use, intrinsic :: iso_c_binding
     type(c_ptr), intent(in), value :: a, b
     integer(c_int) :: cmpfunc
   end function
end interface
interface
   subroutine qsort(ptr,count,size,comp) bind(c,name="qsort")
     use, intrinsic :: iso_c_binding
     type(c_ptr), value :: ptr
     integer(c_size_t), value :: count, size
     type(c_funptr), value :: comp
  end subroutine
end interface
end program my_program