[PATCH] apps: common: dng_writer: Add a default case for switch-case on a modulo

[Laurent Pinchart]

On Wed, Jan 24, 2024 at 11:39:05AM +0000, Kieran Bingham wrote:
> Quoting Paul Elder (2024-01-24 07:56:04)
> > Clearly all cases in the switch are already satisfied, but some
> > compilers fail to realize this and spit out an error:
> > 
> > Compiler version: gcc 11.2.0 "aarch64-buildroot-linux-gnu-gcc.br_real (Buildroot 2021.11) 11.2.0"
> > 
> > ../../src/apps/common/dng_writer.cpp: In function ‘void thumbScanlineIPU3(const FormatInfo&, void*, const void*, unsigned int, unsigned int)’:
> > ../../src/apps/common/dng_writer.cpp:277:55: error: ‘val4’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
> >   277 |                 uint8_t value = (val1 + val2 + val3 + val4) >> 10;
> >       |                                                       ^~~~
> > ../../src/apps/common/dng_writer.cpp:277:48: error: ‘val3’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
> >   277 |                 uint8_t value = (val1 + val2 + val3 + val4) >> 10;
> >       |                                                ^~~~
> > ../../src/apps/common/dng_writer.cpp:277:41: error: ‘val2’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
> >   277 |                 uint8_t value = (val1 + val2 + val3 + val4) >> 10;
> >       |                                         ^~~~
> > ../../src/apps/common/dng_writer.cpp:277:34: error: ‘val1’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
> >   277 |                 uint8_t value = (val1 + val2 + val3 + val4) >> 10;
> >       |                                  ^~~~
> > 
> > Add a default case for the switch-case on a modulo to silence this.
> > 
> > Bug: https://bugs.libcamera.org/show_bug.cgi?id=207
> > Signed-off-by: Paul Elder <paul.elder at ideasonboard.com>
> 
> Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>

I'm really curious to know what gcc is thinking, but that doesn't
prevent me from saying

Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>

> > ---
> >  src/apps/common/dng_writer.cpp | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/src/apps/common/dng_writer.cpp b/src/apps/common/dng_writer.cpp
> > index c945edce7..82bc065a5 100644
> > --- a/src/apps/common/dng_writer.cpp
> > +++ b/src/apps/common/dng_writer.cpp
> > @@ -248,6 +248,7 @@ void thumbScanlineIPU3([[maybe_unused]] const FormatInfo &info, void *output,
> >  
> >                 uint16_t val1, val2, val3, val4;
> >                 switch (pixelInBlock % 4) {
> > +               default:
> >                 case 0:
> >                         val1 = (in[1] & 0x03) << 14 | (in[0] & 0xff) << 6;
> >                         val2 = (in[2] & 0x0f) << 12 | (in[1] & 0xfc) << 4;

-- 
Regards,

Laurent Pinchart