Re: Problem where a function is invoked once but called twice (when invocation is within an allocator).

[Rod Kay <rod.kay@aulace.com>]

On May 6, 3:07 am, Florian Weimer <f...@deneb.enyo.de> wrote:
>
> Could you show the -gnatG output as well?

Source recreated from tree for Tester (body)
--------------------------------------------

with media;
with media.media__video;
with opengl;
with ada.ada__tags;
with system.system__secondary_stack;

procedure tester is
   M13b : system__secondary_stack__mark_id :=
     $system__secondary_stack__ss_mark;

   procedure tester___clean is
   begin
      $system__secondary_stack__ss_release (M13b);
      return;
   end tester___clean;
begin
   the_movie : media.media__video.media__video__view := media.
     media__video.media__video__new_video__2 ("xyz.avi");
   [constraint_error when
     the_movie = null
     "access check failed"]

   -- Case 1 begins here ...
   type tester__A3b is access all opengl__image;
   R4b : constant tester__A3b := media__video__next_frame (the_movie,
     selfL => 0)'reference;
   subtype tester__Tcase_1S is opengl__image (R4b.all'first(1) ..
R4b.all'
     last(1), R4b.all'first(2) .. R4b.all'last(2));
   [constraint_error when
     R4b.all'last(2) >= R4b.all'first(2) and then (R4b.all'first(2) <
       0 or else R4b.all'last(2) > 65535)
     "range check failed"]
   [constraint_error when
     R4b.all'last(1) >= R4b.all'first(1) and then (R4b.all'first(1) <
       0 or else R4b.all'last(1) > 65535)
     "range check failed"]
   case_1 : opengl__image (R4b.all'first(1) .. R4b.all'last(1),
R4b.all'
     first(2) .. R4b.all'last(2)) := R4b.all;

   -- Case 2 begins here ...
   type tester__A10b is access all opengl__image;
   R11b : constant tester__A10b := (media__video__next_frame
(the_movie,
     selfL => 0))'reference;
   subtype tester__A9b is opengl__image ((R11b.all)'first(1) ..
(R11b.all)'
     last(1), (R11b.all)'first(2) .. (R11b.all)'last(2));
   [constraint_error when
     (R11b.all)'last(2) >= (R11b.all)'first(2) and then ((R11b.all)'
       first(2) < 0 or else (R11b.all)'last(2) > 65535)
     "range check failed"]
   [constraint_error when
     (R11b.all)'last(1) >= (R11b.all)'first(1) and then ((R11b.all)'
       first(1) < 0 or else (R11b.all)'last(1) > 65535)
     "range check failed"]
   case_2 : access opengl.opengl__image := new opengl.opengl__image'(
     tester__A9b?((media__video__next_frame (the_movie, selfL =>
0))));
   [subtype tester__T6b is access opengl__image]
   reference tester__T6b
   null;
   return;
at end
   tester___clean;
end tester;



   For Case_2, it appears the 1st call to next_Frame is used purely to
get the bounds of the returned array. The bounds are then used to
define 'tester__A9b' which is a subtype of opengl.Image of the correct
size. 'tester__A9b' is then used to convert the result of the 2nd call
to next_Frame, during allocation.