groveller's :define-constants doesn't work with cenum

[Martin Kielhorn]

I tried to use the cffi groveller to create a binding for <linux/videodev2.h>

The following definition:

(cenum (v4l2_buf_type :define-constants t) ((:capture "V4L2_BUF_TYPE_VIDEO_CAPTURE")))

leads to this code in the auto-generated C-file:

  /* constant section for CAPTURE */
#ifdef V4L2_BUF_TYPE_VIDEO_CAPTURE
  fputs("(cl:defconstant ", output);
  fputs("capture", output);
  fputs(" ", output);
  if(_64_BIT_VALUE_FITS_SIGNED_P(V4L2_BUF_TYPE_VIDEO_CAPTURE))
    fprintf(output, "%lli", (int64_t) V4L2_BUF_TYPE_VIDEO_CAPTURE);
  else
    fprintf(output, "%llu", (uint64_t) V4L2_BUF_TYPE_VIDEO_CAPTURE);
  fputs(")\n", output);
#else
  fputs("(cl:warn 'cffi-grovel:missing-definition :name 'CAPTURE)\n", output);
#endif

The V4L2_BUF_TYPE_VIDEO_CAPTURE is part of a C enum and no preprocessor macro.
Therefore, the #ifdef is undefined and the processed grovel file just contains the line

(cl:warn 'cffi-grovel:missing-definition :name 'CAPTURE)

instead of the expected constant definition.

I use cffi_0.11.2 and SBCL 1.1.14.30-ba008a7 on x86_64 GNU/Linux.

[Luís Oliveira (luismbo)]

[cc'ing Stelian Ionescu]

On Thu, Jan 23, 2014 at 5:37 PM, Martin Kielhorn
<email address hidden> wrote:
> (cenum (v4l2_buf_type :define-constants t) ((:capture
> "V4L2_BUF_TYPE_VIDEO_CAPTURE")))
[...]
> /* constant section for CAPTURE */
> #ifdef V4L2_BUF_TYPE_VIDEO_CAPTURE

Stelian: git-blame says you implemented the :DEFINE-CONSTANTS option
for CENUM. The implementation delegates the work to the CONSTANT
grovel form but that shouldn't work because the C preprocessor doesn't
know about enums. Did that ever work?

[Elias Martenson (lokedhs)]

I came across this problem when building a CFFI interface to RabbitMQ, which also uses enums extensively.