On 9/8/2017 2:18 PM, Hans Wennborg via cfe-commits wrote:
On Fri, Sep 8, 2017 at 2:09 PM, Roman Lebedev <lebedev...@gmail.com> wrote:
Interesting. My first thought was to explicitly specify enum as signed:
enum MediaDeviceType : signed int {
MEDIA_DEVICE_TYPE_AUDIO_INPUT = 0,
MEDIA_DEVICE_TYPE_VIDEO_INPUT,
MEDIA_DEVICE_TYPE_AUDIO_OUTPUT,
NUM_MEDIA_DEVICE_TYPES,
};
inline bool IsValidMediaDeviceType(MediaDeviceType type) {
return type >= 0U && type < NUM_MEDIA_DEVICE_TYPES;
}
But it still seem to warn, and *that* sounds like a bug.
Please open a new bugreport.
I'm reporting it here :-)
As for different default signedness, i'm not sure what is there to do. Does
not sound like a problem for this diagnostic to intentionally avoid to
be honest.
I think it is a problem for this warning. If a user sees the warning
and removes the "type >= 0" check, thinking that it was unnecessary
because the compiler told them so, they have now introduced a bug in
the code.
Even if you declare the enum type as signed, it still isn't allowed to
contain a negative number; that's undefined behavior. You can check for
this using ubsan's -fsanitize=enum.
-Eli
--
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux
Foundation Collaborative Project
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