Fwd: Re: [cffi-devel] cffi changes are generating deprecation warning in cl-gd now

[Jeff Cunningham]

I received this response from Liam Healy over in cffi-devel and am 
posting his response. I have also done as Edi suggested and submitted an 
issue on cl-gd at github.

--Jeff


-------- Original Message --------
Subject: 	Re: [cffi-devel] cffi changes are generating deprecation 
warning in cl-gd now
Date: 	Mon, 27 Jan 2014 21:07:11 -0700
From: 	Liam Healy <lnp at healy.washington.dc.us>
To: 	Jeff Cunningham <jeffrey at jkcunningham.com>
CC: 	CFFI <cffi-devel at common-lisp.net>, cl-gd-devel at common-lisp.net



Hi Jeff,

It's harmless, it's just telling you that the syntax that cl-gd uses for 
structure arguments will eventually (in a future version of CFFI) not 
work. The messages describes the problem. The structure is specified as 
cl-gd::gd-image  in a function argument or return value. In the old 
versions of CFFI, that was interpreted as a pointer to that structure, 
because there was no other possibility. Now structures can also be 
passed/returned by value using cffi-libffi, so you have to say 
explicitly as the error message indicates. They might also need to 
change the use of #'mem-aref (which before returned a pointer to the 
structure but now returns the structure itself) into a #'mem-aptr.

I'm not subscribed to the cl-gd-devel list, so you should forward this 
response there.

Liam


On Mon, Jan 27, 2014 at 4:42 PM, Jeff Cunningham 
<jeffrey at jkcunningham.com <mailto:jeffrey at jkcunningham.com>> wrote:

    Hi;

    A short while ago I started noticing this error message showing up

    ;; STYLE-WARNING:
    ;;    bare references to struct types are deprecated. Please use
    (:POINTER (:STRUCT CL-GD::GD-IMAGE))
    ;;    or (:STRUCT CL-GD::GD-IMAGE) instead.

    It took me awhile to extract a simple demo case, but I've narrowed
    it down to the WITH-THICKNESS macro call I believe.
    I'm not sure which list would be best for this question, so I
    cross-posted it.

    Here's a test case.

    (ql:quickload "cl-gd")
    (use-package :cl-gd)

    (let* ((x1 -86)
            (x2 529)
            (y1 -0.13)
            (y2 1.16)
            (xv '(0.0 1.0 2.0 3.0 4.0))
            (yv '(0.99 0.12 0.66 0.24 0.075)))
       (with-image* (500 250)
         (allocate-color 255 255 255)
         (let ((c (allocate-color 0 0 255)))
           (with-transformation (:x1 x1 :x2 x2 :y1 y1 :y2 y2)
             (with-thickness (1)
               (mapl #'(lambda (x y)
                         (when (and (cdr x) (cdr y))
                           (draw-line (car x) (car y) (cadr x) (cadr y)
    :color c))) xv yv))
             (write-image-to-file "test.png" :if-exists :supersede)))))

    If you take out the with-thickness macro call the message disappears.

    I played around with that macro but don't really understand enough
    about the intricacies of cffi to fix it.
    Does anyone have any ideas? Here's the macro in question:

    (defmacro with-thickness ((thickness &key (image '*default-image*))
    &body body)
       "Executes BODY with the current line width of IMAGE set to
    THICKNESS. The image's previous line width is guaranteed to be
    restored before the macro exits. Note that the line width is measured
    in pixels and is not affected by WITH-TRANSFORMATION."
       (cl-gd::with-unique-names (old-thickness)
         ;; we rebind everything so we have left-to-right evaluation
         (cl-gd::with-rebinding (thickness image)
           `(let ((,old-thickness (thickness ,image)))
              (unwind-protect
                  (progn
                    (setf (thickness ,image) ,thickness))
                , at body)
              (setf (thickness ,image) ,old-thickness)))))


    Much obliged.

    --Jeff Cunningham





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