[4.5, Patch, Fortran] PR 36704: Procedure pointer as function result

[Daniel Kraft]

Janus Weil wrote:
> here is my patch for procedure pointers as function result. The easy
> case of procptr function results (i.e. using a result variable) is
> already working on 4.4 trunk. This patch has the ambition to also make
> the harder cases work where no result variable is used. After thinking
> about it for a while, I came to the conclusion that the best way of
> implementing this would be to add a "hidden" result variable for those
> cases where no actual RESULT statement is used. The primary motivation
> for this is that the interface of the returned procptr must be kept
> separate from the interface of the function which returns the procptr,
> i.e. we need two separate symbols. The hidden result variable should
> have a name which is not a valid Fortran variable name, and I simply
> chose "ppr@" (for procedur pointer result, plus the @ to make it
> invalid). If anyone thinks this is a poor choice for some reason, I
> can easily change this of course.

Hi Janus,

thanks for this patch!  Your plan about the hidden result variable seems 
fine with me, but I've not yet had time to look at the patch (and am 
probably not the best one to review it in general).  I will try to read 
through it though and post comments if I have some :)

It seems 4.5-time has started for gfortran by now...  So then I will 
take up type-bound procedures again and start on DEFERRED ;)

Cheers,
Daniel

> I also attached a testcase, which should give you an idea of what the
> patch is able to handle. I tried to include all the different ways to
> declare a procedure pointer, and hope I forgot none. Possibly there
> are still some details missing, but I'd like to have the general
> concept of the patch reviewed already. Maybe someone even has an idea
> how this can be done in a simpler way. I think it's kind of tricky.
> The patch actually grew piece by piece, since I started with the easy
> cases and made my way towards the harder ones. Also I'd appreciate it
> very much if someone could test the patch from a "user's perspective",
> to uncover those usage cases that I am missing.
> 
> Regtested on i686-pc-linux-gnu without any failures.
> 
> Cheers,
> Janus
> 
> 
> 
> 2008-12-06  Janus Weil  <janus@gcc.gnu.org>
> 
> 	PR fortran/36704
> 	* decl.c (add_hidden_procptr_result): New function for handling
> 	procedure pointer return values by adding a hidden result variable.
> 	(variable_decl,match_procedure_decl,gfc_match_function_decl,
> 	gfc_match_subroutine,gfc_match_end,attr_decl1): Handle procedure pointer
> 	return values.
> 	* primary.c (match_variable): Replace symbol with hidden result
> 	variable.
> 	* resolve.c (resolve_contained_fntype): Allow for procedure pointer
> 	function results.
> 	(resolve_fl_procedure): Conflict detection moved here from
> 	'check_conflict'.
> 	* symbol.c (gfc_check_function_type): Allow for procedure pointer
> 	function results.
> 	(check_conflict): Move some conflict detection to resolution stage.
> 
> 
> 2008-12-06  Janus Weil  <janus@gcc.gnu.org>
> 
> 	PR fortran/36704
> 	* gfortran.dg/external_procedures_1.f90: Modified.
> 	* gfortran.dg/proc_ptr_13.f90: New.
> 


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