language lawyer question

[Paul Brook]

On Friday 21 January 2005 06:10, Paul Thomas wrote:
> The problem lies in this function:
>
>    function getOa(ob) result(oa)
>       type(objB),target :: ob
>       type(objA), pointer :: oa
>       oa=>ob%oa
>    end function getOa

From the draft F95 standard:
Section 14.6.2.1.3 "Events that cause the association status of a pointer to 
become undefined":
"(3) Execution of a RETURN or END statement that causes a pointer's target to 
become undefined."

Section 14.7.6 "Events that cause variables to become undefined":
"(3) The execution of a RETURN or END statement within a subprogram causes all 
variables local to its scoping unit [...] to become undefined [...]"

None of the exceptions listed apply to the case above.

Thus the return value of getOa (oa) has undefined pointer association status 
after getOa has returned.
A compiler might allocate ob on the stack, so it will be freed when getOa 
returns.

One way to avoid this is to mark ob as SAVEd

Paul