Hi Mikael,

> Gesendet: Mittwoch, 05. Oktober 2022 um 12:34 Uhr
> Von: "Mikael Morin" <morin-mikael@orange.fr>
> Please move the check to resolve_transfer in resolve.cc.

I have done this, see attached updated patch.

Regtests cleanly on x86_64-pc-linux-gnu.

> Strangely, the patch doesn't seem to fix the problem on the testcase
> here.  There is an outer parenthese expression preventing the condition
> you added from triggering.  Can you double check?

You are right: I had a one-liner in my worktree from PR105371 that
fixes an issue with gfc_simplify_merge and that seems to help here.
It is now included.

> If we take the standard to the letter, only output items are forbidden,
> so a check is missing for writing context.  I don't know how it can work
> for input items though, so maybe not worth it.  In any case, the error
> shouldn't mention output items in reading context.
>
> Here is a variant of the testcase with procedure pointer components,
> that fails differently but can probably be caught as well.
>
> program p
>    implicit none
>    type :: t
>      procedure(f), pointer, nopass :: b
>    end type t
>    type(t) :: a
>
>    interface
>      real function f()
>      end function f
>    end interface
>
>    print *, merge (a%b, a%b, .true.)
> end

I hadn't thought about this, and found a solution that also fixes this
one.  Great example!  This is now an additional test.

OK for mainline?

And thanks for your comments!

Harald