Fortran `shlex` library

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Is this always true?

In the F202X (now F2023) proposals, there were multiple versions of split:

SPLIT (STRING, SET, TOKENS [, SEPARATOR])
SPLIT (STRING, SET, FIRST, LAST)
SPLIT (STRING, SET, POS [, BACK])

which can be implemented in Fortran and exported under a generic interface:

  interface split
    module procedure :: split_tokens, split_first_last, split_pos
  end interface split

As long as the split routines in shlex have arguments which differ in type, kind, and rank, the specific routine needed can be resolved.

One caveat in this case is that the intrinsic split is a subroutine, whereas in fortran-shlex, split is a function. This is prohibited as demonstrated by this example:

module bar
private
public :: random_number
interface random_number
   module procedure random_pair
end interface
contains
   subroutine random_pair(a,b)
      real :: a, b
      call random_number(a)
      call random_number(b)
   end subroutine
end module

module foo
use bar
type :: pair
   real :: a, b
end type
interface random_number
   module procedure random_pair
end interface
contains
   function random_pair()
      type(pair) :: random_pair
      call random_number(random_pair%a,random_pair%b)
   end function
end module

which fails to compile with the following error:

/app/example.f90:16:4:

   16 | use bar
      |    1
Error: In generic interface 'random_number' at (1) procedures must be either all SUBROUTINEs or all FUNCTIONs
Compiler returned: 1

Addendum: the rule above does not apply for the case of intrinsics. I can modify the module bar as follows:

module foo
!use bar
type :: pair
   real :: a, b
end type
interface random_number
   module procedure random_pair
end interface
contains
   function random_pair()
      type(pair) :: random_pair
      intrinsic :: random_number
      call random_number(random_pair%a)
      call random_number(random_pair%b)
   end function
end module

But now, as @everythingfunctional says, the intrinsic subroutine is shadowed.