[libcamera-devel] libcamera: media_device: error: ‘ifaceId’ may be used uninitialised in this function

[Jacopo Mondi]

Hi Kieran,

On Tue, Mar 19, 2019 at 09:42:31AM +0000, Kieran Bingham wrote:
> Hi Jacopo,
>
> I'm integrating libcamera into buildroot, and I've hit the following:
>
> Compiling libcamera on aarch64 currently fails with the following
> warning treated as an error:

Thanks for reporting this.

>
> [12/87] Compiling C++ object
> 'src/libcamera/4ab8042@@camera at sha/media_device.cpp.o'.
> FAILED: src/libcamera/4ab8042@@camera at sha/media_device.cpp.o
> /home/linuxembedded/iob/libcamera/buildroot/libcamera/arm64/host/bin/aarch64-linux-gnu-g++
> -Isrc/libcamera/4ab8042@@camera at sha -Isrc/libcamera -I../src/libcamera
> -Iinclude -I../include -I../src/libcamera/include
> -I/home/linuxembedded/iob/libcamera/buildroot/libcamera/arm64/host/usr/bin/../aarch64-buildroot-linux-gnu/sysroot/usr/include
> -fdiagnostics-color=always -pipe -D_FILE_OFFSET_BITS=64 -Wall
> -Winvalid-pch -Wnon-virtual-dtor -Wextra -Werror -std=c++11 -O3
> -Wno-unused-parameter -fPIC -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE
> -D_FILE_OFFSET_BITS=64 -Os -MD -MQ
> 'src/libcamera/4ab8042@@camera at sha/media_device.cpp.o' -MF
> 'src/libcamera/4ab8042@@camera at sha/media_device.cpp.o.d' -o
> 'src/libcamera/4ab8042@@camera at sha/media_device.cpp.o' -c
> ../src/libcamera/media_device.cpp
> ../src/libcamera/media_device.cpp: In member function
> ‘media_v2_interface* libcamera::MediaDevice::findInterface(const
> media_v2_topology&, unsigned int)’:
> ../src/libcamera/media_device.cpp:540:3: error: ‘ifaceId’ may be used
> uninitialised in this function [-Werror=maybe-uninitialized]
>    if (ifaces[i].id == ifaceId)
>    ^~
> cc1plus: all warnings being treated as errors
> [20/87] Compiling C++ object
> 'src/libcamera/4ab8042@@camera at sha/pipeline_uvcvideo.cpp.o'.
> ninja: build stopped: subcommand failed.
>
>
> I've hacked in a
>
> -unsigned int ifaceId;
> +unsigned int ifaceId = 0;
>
> for the moment, but could you take a look at this please and see what
> the correct resolution would be? (perhaps it is to just initialise to 0).

I think it's fine to initialize it to 0 just to silence the compiler.

The code is correct afaict: if ifaceId does not get initalized, we
exit from the function before hitting line 540, which the compiler
complains about.

If you're willing to send a patch to intialize ifaceId, please have
mine:

Acked-by: Jacopo Mondi <jacopo at jmondi.org>

Thanks
  j

>
> --
> Regards
> --
> Kieran
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