Re: [cl-sdl-help] %SAP-ALIEN

[David M. <sv...@ya...>]

Lars Brinkhoff wrote:
> Using SBCL 0.8.16 on a PowerPC, I'm getting the classical error
> message below.  I understand there's a solution to this involving
> type declarations, but I don't know where to put them.  Should I
> hack the internals of CL-SDL?
> 
> This small program is sufficient to get the message:
>   (progn
>     (sdl:init sdl:+init-video+)
>     (cl-sdl:clear-screen (sdl:set-video-mode 512 512 32 sdl:+hwsurface+))
>     (sdl:quit))
> 
> ; in: LAMBDA NIL
> ;     (SB-ALIEN-INTERNALS:NATURALIZE
> ;    (SB-SYS:SAP+ SB-ALIEN::SAP (/ SB-ALIEN::OFFSET SB-VM:N-BYTE-BITS
> ;    '#<SB-ALIEN-INTERNALS:ALIEN-RECORD-TYPE (STRUCT SDL:SURFACE ...))))
> ; ==>
> ;   (SB-ALIEN-INTERNALS:%SAP-ALIEN
> ;    ALIEN '#<SB-ALIEN-INTERNALS:ALIEN-RECORD-TYPE (STRUCT SDL:SURFACE ...))
> ; note: unable to
> ;   optimize
> ; because:
> ;   could not optimize away %SAP-ALIEN: forced to do runtime
> ; allocation of alien-value structure

Are you really worried about effeciency in this example, or just trying 
to get a clean compile?  Because sdl:set-video-mode is going to take 
lots, lots more time than consing up a little ol' alien wrapper object 
on the heap.  (the latter is what the warning is complaining about).

On the sbcl-help list I'm trying to drum up popular support for getting 
this error message to be either shorter & less dire sounding, or 
possibly non-existant.  However, so far I'm yelling into the wind, so if 
you'd care to lend your voice, it'd be appreciated.  :)