(j3.2006) a question on c_f_pointer call

[Jim Xia]

j3-bounces at j3-fortran.org wrote on 08/25/2010 04:37:56 PM:

> dummy t (this is the target) really carry information in it that it is a 

> valid "deallocation target".  When do you actually calculate that (if I 
> changed 11:2:-1 to 11:3:-1 it would no longer be valid to deallocate 
it).
> 
> I am not saying you are wrong, and certainly not saying that there is no 

> confusion as to what errors the processor must detect correctly and 
> report. But I am still not convinced that c_f_pointer does anything more 

> or less than can already be done using external procedures that do 
> pointer assignments to make a pointer point to some target.
> 
> Thanks,
> Aleks
> 


I believe this is an area not considered carefully by the standard.  The 
c_f_pointer() only takes one pointer (in Fortran's sense): FPTR which 
carries the information as to whether the pointer can be deallocated.  The 
argument CPTR is not a Fortran pointer.  So when you do the pointer 
association, there are missing information as to whether this pointer can 
be deallocated or not.  Fortran array section 11:2:-1 is constructed by 
Fortran compiler (using a descriptor), therefore the compiler knows every 
piece of information about the section.  C_F_POINTER, in this sense, is 
quite different from user code purely written in Fortran.

Cheers,

Jim Xia

XL Fortran Compiler Test
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