Provide a do nothing function.

[awvwgk]

This is a proposal to implement a function that does nothing with its input arguments. I used a function like the one below to do nothing but acknowledge a compiler warning on an used dummy argument, which wasn't needed in the given context but couldn't be removed from the function signature. What do you think is there a need for such function in stdlib?

!> Do nothing but mark an unused dummy argument as such to acknowledge compile
!> time warning like:
!>
!>   Warning: Unused dummy argument ‘dummy’ at (1) [-Wunused-dummy-argument]
!>
!> We deeply trust in the compiler to inline and optimize this piece of code away.
elemental subroutine unused_dummy_argument(dummy)
  class(*), intent(in) :: dummy
  associate(dummy => dummy); end associate
end subroutine unused_dummy_argument

[ivan-pi]

How can we be sure some compiler doesn't expand their definition of unused dummy arguments to include association without further usage? This would then yield new meaningless warnings.

While I find those errors annoying in the case when dummy variables are required to match an abstract interface, I am skeptical whether this is really a better solution than simply acknowledging the unused variable in the documentation.

In a subroutine with unused dummy variables, the caller still needs to provide them. An error message will at-least indicate to the developer those variables are unused. If the errors are silenced, the developer might wrongly believe their value must be set or has potentially changed.