From: "Jason L Tibbitts III" <tibbs@math.uh.edu>
To: Sakari Ailus <sakari.ailus@iki.fi>
Cc: "Rémi Denis-Courmont" <remi@remlab.net>,
"Mauro Carvalho Chehab" <mchehab@redhat.com>,
"Hans Verkuil" <hans.verkuil@cisco.com>,
linux-kernel@vger.kernel.org
Subject: Commit 6016af "[media] v4l2: use __u32 rather than enums in ioctl() structs" breaks C++ users of V4L2
Date: Mon, 16 Jul 2012 15:40:01 -0500 [thread overview]
Message-ID: <ufabojfv3ry.fsf@epithumia.math.uh.edu> (raw)
I ran into problems compiling the program ZoneMinder on Fedora rawhide
(currently using something around 3.5rc6) which do not appear with 3.4
kernels. With help this was traced to commit
6016af82eafcb6e086a8f2a2197b46029a843d68, "[media] v4l2: use __u32
rather than enums in ioctl() structs" which changed videodev2.h in a way
which appears to be incompatible with C++.
This results in code such as the following:
enum v4l2_buf_type type = v4l2_data.fmt.type;
failing to compile with:
zm_local_camera.cpp:1523:49: error: invalid conversion from '__u32
{aka unsigned int}' to 'v4l2_buf_type' [-fpermissive]
but only when compiled with the headers from a 3.5 kernel.
I'm very far from a C++ expert. I talked with some people who do grok
it and the issue comes down to restrictions on assignments of ints to
enums and additionally that enums in C++ don't have defined size.
- J<
next reply other threads:[~2012-07-16 21:30 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-16 20:40 Jason L Tibbitts III [this message]
2012-07-17 4:39 ` Commit 6016af "[media] v4l2: use __u32 rather than enums in ioctl() structs" breaks C++ users of V4L2 Rémi Denis-Courmont
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