Possible narrowing conversion build fix for Compositor API example.

Possible narrowing conversion build fix for Compositor API example.

In the compositor API example gcc 4.9 reports a possible
type narrowing when using fabs call. To fix this use fabsf instead.

BUG=385988
R=dmichael

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=278076

[elecro, 2014-06-17 13:00:32]

After the https://codereview.chromium.org/298023004 review landed, when building
with gcc 4.9 the following error occurs:

CXX obj/ppapi/examples/compositor/ppapi_example_compositor.compositor.o
ppapi/examples/compositor/compositor.cc: In member function 'void
{anonymous}::DemoInstance::Paint(int32_t, int32_t)':
ppapi/examples/compositor/compositor.cc:312:24: error: narrowing conversion of
'(((double)__builtin_abs(factor_sin)) + 2.0000000298023224e-1)' from 'double' to
'const float' inside { } is ill-formed in C++11 [-Werror=narrowing]
ppapi/examples/compositor/compositor.cc:313:30: error: narrowing conversion of
'(((double)__builtin_abs(factor_sin)) + 2.0000000298023224e-1)' from 'double' to
'const float' inside { } is ill-formed in C++11 [-Werror=narrowing]
cc1plus: all warnings being treated as errors

[dmichael (off chromium), 2014-06-17 16:16:00]

Thanks for the patch. IMO, this is a bug in GCC, so I would recommend making a
small reproducer and filing a bug with them.

But I'm fine with this patch, too. Seems harmless to us if it helps you.

lgtm

https://codereview.chromium.org/335383003/diff/1/ppapi/examples/compositor/co...
File ppapi/examples/compositor/compositor.cc (right):

https://codereview.chromium.org/335383003/diff/1/ppapi/examples/compositor/co...
ppapi/examples/compositor/compositor.cc:313: 0.0f, fabsf(factor_sin) + 0.2f,
0.0f, 0.0f,
factor_sin is a float, and fabs is supposed to have an overload for float...
http://www.cplusplus.com/reference/cmath/fabs/
(see also 26.5p6 in C++03, 26.8p9 in C++11).

This seems to me like a bug GCC 4.9's C++11 support. We also don't yet build
Chromium in C++11 mode, so I'd be surprised if you didn't run in to other
problems.

You might consider making a small reproducer and filing a bug with GCC.

[elecro, 2014-06-18 08:21:14]

On 2014/06/17 16:16:00, dmichael wrote:
> Thanks for the patch. IMO, this is a bug in GCC, so I would recommend making a
> small reproducer and filing a bug with them.
> 

Yeah, I also think this is some kind of GCC bug. I'll look around in the GCC
bugzilla if there is anything like this and if not I'll report it.

Thanks.

[elecro, 2014-06-18 08:21:17]

The CQ bit was checked by pgal.u-szeged@partner.samsung.com

[commit-bot: I haz the power, 2014-06-18 08:26:52]

CQ is trying da patch. Follow status at

https://chromium-status.appspot.com/cq/pgal.u-szeged@partner.samsung.com/3353...

[commit-bot: I haz the power, 2014-06-18 15:08:27]

Change committed as 278076