A fix for annoying clang error "unused-const-variabl" in third_party code.

A fix for annoying clang error "unused-const-variabl" in third_party code.

../../third_party/externals/libwebp/src/enc/quant.c:105:23: error: unused variable 'kCoeffThresh' [-Werror,-Wunused-const-variable]
static const uint16_t kCoeffThresh[16] = {
                              ^
                      1 error generated.

BUG=None
TEST=build with clang, ninja -C out/Debug most.
R=bsalomon@google.com,epoger@google.com,thakis@chromium.org

Committed: http://code.google.com/p/skia/source/detail?r=11990

[tfarina, 2013-10-28 18:03:41]

I know this is not the right fix, but I put it here for review so we can find
the right way.

Thanks in advance for your review!

[mtklein, 2013-10-28 18:20:15]

On 2013/10/28 18:03:41, tfarina wrote:
> I know this is not the right fix, but I put it here for review so we can find
> the right way.
> 
> Thanks in advance for your review!

I think what we typically do is add -w to cflags for the offending package. 
E.g., gyp/poppler.gyp.

Out of curiosity, what version of clang are you building on, and which platform?
 This one doesn't show up for me with Clang 3.3 that I built myself on x86-64
Linux.

[tfarina, 2013-10-28 19:28:29]

My original approach, that doesn't work.

Mike, please, review my patch set 2 and help me figure out why it does NOT work.

Thanks,

[tfarina, 2013-10-28 19:29:20]

On 2013/10/28 18:20:15, mtklein wrote:
> On 2013/10/28 18:03:41, tfarina wrote:
> > I know this is not the right fix, but I put it here for review so we can
find
> > the right way.
> > 
> > Thanks in advance for your review!
> 
> I think what we typically do is add -w to cflags for the offending package. 
> E.g., gyp/poppler.gyp.
> 
> Out of curiosity, what version of clang are you building on, and which
platform?
>  This one doesn't show up for me with Clang 3.3 that I built myself on x86-64
> Linux.

I use the one provided by chromium:

$ clang --version
clang version 3.4 (trunk 192869)
Target: x86_64-unknown-linux-gnu
Thread model: posix

$ which clang
/home/tfarina/chromium/src/third_party/llvm-build/Release+Asserts/bin/clang

[mtklein, 2013-10-28 19:37:36]

https://codereview.chromium.org/47603012/diff/70001/gyp/libwebp.gyp
File gyp/libwebp.gyp (right):

https://codereview.chromium.org/47603012/diff/70001/gyp/libwebp.gyp#newcode18
gyp/libwebp.gyp:18: 'cflags!': [ '-Wno-unused-const-variable', ],
Try removing the "!"?  That means "remove this", doesn't it?

[tfarina, 2013-10-28 19:49:11]

https://codereview.chromium.org/47603012/diff/70001/gyp/libwebp.gyp
File gyp/libwebp.gyp (right):

https://codereview.chromium.org/47603012/diff/70001/gyp/libwebp.gyp#newcode18
gyp/libwebp.gyp:18: 'cflags!': [ '-Wno-unused-const-variable', ],
On 2013/10/28 19:37:37, mtklein wrote:
> Try removing the "!"?  That means "remove this", doesn't it?
I tried both ways, with and without. It doesn't work either.
That is frustrating! I uploaded the version without "!" in patch set 3. PTAL.

[mtklein, 2013-10-28 20:05:53]

On 2013/10/28 19:49:11, tfarina wrote:
> https://codereview.chromium.org/47603012/diff/70001/gyp/libwebp.gyp
> File gyp/libwebp.gyp (right):
> 
> https://codereview.chromium.org/47603012/diff/70001/gyp/libwebp.gyp#newcode18
> gyp/libwebp.gyp:18: 'cflags!': [ '-Wno-unused-const-variable', ],
> On 2013/10/28 19:37:37, mtklein wrote:
> > Try removing the "!"?  That means "remove this", doesn't it?
> I tried both ways, with and without. It doesn't work either.
> That is frustrating! I uploaded the version without "!" in patch set 3. PTAL.

Huh, I'd love to help but I can't reproduce the problem.  Here's what I'm doing,
again 64-bit Linux:

$ which clang
/ssd/chromium/src/third_party/llvm-build/Release+Asserts/bin/clang

$ which clang++
/ssd/chromium/src/third_party/llvm-build/Release+Asserts/bin/clang++

$ clang --version
clang version 3.4 (trunk 192869)
Target: x86_64-unknown-linux-gnu
Thread model: posix

$ clang++ --version
clang version 3.4 (trunk 192869)
Target: x86_64-unknown-linux-gnu
Thread model: posix

$ echo $CC $CXX
clang clang++

$ cd ~/skia/trunk; rm -rf out/

$ ./gyp_skia && ninja -C out/Debug && ninja -C out/Release && echo ok
Updating projects from gyp files...
ninja: Entering directory `out/Debug'
100% STAMP obj/gyp/most.actions_depends.stamp
ninja: Entering directory `out/Release'
100% STAMP obj/gyp/most.actions_depends.stamp
ok

No warnings!  Are you doing anything different than me?

[tfarina, 2013-10-28 21:16:53]

On 2013/10/28 20:05:53, mtklein wrote:
> On 2013/10/28 19:49:11, tfarina wrote:
> > https://codereview.chromium.org/47603012/diff/70001/gyp/libwebp.gyp
> > File gyp/libwebp.gyp (right):
> > 
> >
https://codereview.chromium.org/47603012/diff/70001/gyp/libwebp.gyp#newcode18
> > gyp/libwebp.gyp:18: 'cflags!': [ '-Wno-unused-const-variable', ],
> > On 2013/10/28 19:37:37, mtklein wrote:
> > > Try removing the "!"?  That means "remove this", doesn't it?
> > I tried both ways, with and without. It doesn't work either.
> > That is frustrating! I uploaded the version without "!" in patch set 3.
PTAL.
> 
> Huh, I'd love to help but I can't reproduce the problem.  Here's what I'm
doing,
> again 64-bit Linux:
> 
> $ which clang
> /ssd/chromium/src/third_party/llvm-build/Release+Asserts/bin/clang
> 
> $ which clang++
> /ssd/chromium/src/third_party/llvm-build/Release+Asserts/bin/clang++
> 
> $ clang --version
> clang version 3.4 (trunk 192869)
> Target: x86_64-unknown-linux-gnu
> Thread model: posix
> 
> $ clang++ --version
> clang version 3.4 (trunk 192869)
> Target: x86_64-unknown-linux-gnu
> Thread model: posix
> 
> $ echo $CC $CXX
> clang clang++
> 
> $ cd ~/skia/trunk; rm -rf out/
> 
> $ ./gyp_skia && ninja -C out/Debug && ninja -C out/Release && echo ok
> Updating projects from gyp files...
> ninja: Entering directory `out/Debug'
> 100% STAMP obj/gyp/most.actions_depends.stamp
> ninja: Entering directory `out/Release'
> 100% STAMP obj/gyp/most.actions_depends.stamp
> ok
> 
> No warnings!  Are you doing anything different than me?

Almost the same. The difference is that I ran 'gclient sync'.

It says libwebp is at 3fe91635df8734b23f3c1b9d1f0c4fa8cfaf4e39.

May be that is why you aren't seeing this error?

[mtklein, 2013-10-28 21:30:27]

On 2013/10/28 21:16:53, tfarina wrote:
> On 2013/10/28 20:05:53, mtklein wrote:
> > On 2013/10/28 19:49:11, tfarina wrote:
> > > https://codereview.chromium.org/47603012/diff/70001/gyp/libwebp.gyp
> > > File gyp/libwebp.gyp (right):
> > > 
> > >
> https://codereview.chromium.org/47603012/diff/70001/gyp/libwebp.gyp#newcode18
> > > gyp/libwebp.gyp:18: 'cflags!': [ '-Wno-unused-const-variable', ],
> > > On 2013/10/28 19:37:37, mtklein wrote:
> > > > Try removing the "!"?  That means "remove this", doesn't it?
> > > I tried both ways, with and without. It doesn't work either.
> > > That is frustrating! I uploaded the version without "!" in patch set 3.
> PTAL.
> > 
> > Huh, I'd love to help but I can't reproduce the problem.  Here's what I'm
> doing,
> > again 64-bit Linux:
> > 
> > $ which clang
> > /ssd/chromium/src/third_party/llvm-build/Release+Asserts/bin/clang
> > 
> > $ which clang++
> > /ssd/chromium/src/third_party/llvm-build/Release+Asserts/bin/clang++
> > 
> > $ clang --version
> > clang version 3.4 (trunk 192869)
> > Target: x86_64-unknown-linux-gnu
> > Thread model: posix
> > 
> > $ clang++ --version
> > clang version 3.4 (trunk 192869)
> > Target: x86_64-unknown-linux-gnu
> > Thread model: posix
> > 
> > $ echo $CC $CXX
> > clang clang++
> > 
> > $ cd ~/skia/trunk; rm -rf out/
> > 
> > $ ./gyp_skia && ninja -C out/Debug && ninja -C out/Release && echo ok
> > Updating projects from gyp files...
> > ninja: Entering directory `out/Debug'
> > 100% STAMP obj/gyp/most.actions_depends.stamp
> > ninja: Entering directory `out/Release'
> > 100% STAMP obj/gyp/most.actions_depends.stamp
> > ok
> > 
> > No warnings!  Are you doing anything different than me?
> 
> Almost the same. The difference is that I ran 'gclient sync'.
> 
> It says libwebp is at 3fe91635df8734b23f3c1b9d1f0c4fa8cfaf4e39.
> 
> May be that is why you aren't seeing this error?

Reproduced and fixed!  Please take a look at patch set 4.  (Obviously, it LGTM.)

[tfarina, 2013-10-28 21:40:11]

On 2013/10/28 21:30:27, mtklein wrote:
> On 2013/10/28 21:16:53, tfarina wrote:
> > On 2013/10/28 20:05:53, mtklein wrote:
> > > On 2013/10/28 19:49:11, tfarina wrote:
> > > > https://codereview.chromium.org/47603012/diff/70001/gyp/libwebp.gyp
> > > > File gyp/libwebp.gyp (right):
> > > > 
> > > >
> >
https://codereview.chromium.org/47603012/diff/70001/gyp/libwebp.gyp#newcode18
> > > > gyp/libwebp.gyp:18: 'cflags!': [ '-Wno-unused-const-variable', ],
> > > > On 2013/10/28 19:37:37, mtklein wrote:
> > > > > Try removing the "!"?  That means "remove this", doesn't it?
> > > > I tried both ways, with and without. It doesn't work either.
> > > > That is frustrating! I uploaded the version without "!" in patch set 3.
> > PTAL.
> > > 
> > > Huh, I'd love to help but I can't reproduce the problem.  Here's what I'm
> > doing,
> > > again 64-bit Linux:
> > > 
> > > $ which clang
> > > /ssd/chromium/src/third_party/llvm-build/Release+Asserts/bin/clang
> > > 
> > > $ which clang++
> > > /ssd/chromium/src/third_party/llvm-build/Release+Asserts/bin/clang++
> > > 
> > > $ clang --version
> > > clang version 3.4 (trunk 192869)
> > > Target: x86_64-unknown-linux-gnu
> > > Thread model: posix
> > > 
> > > $ clang++ --version
> > > clang version 3.4 (trunk 192869)
> > > Target: x86_64-unknown-linux-gnu
> > > Thread model: posix
> > > 
> > > $ echo $CC $CXX
> > > clang clang++
> > > 
> > > $ cd ~/skia/trunk; rm -rf out/
> > > 
> > > $ ./gyp_skia && ninja -C out/Debug && ninja -C out/Release && echo ok
> > > Updating projects from gyp files...
> > > ninja: Entering directory `out/Debug'
> > > 100% STAMP obj/gyp/most.actions_depends.stamp
> > > ninja: Entering directory `out/Release'
> > > 100% STAMP obj/gyp/most.actions_depends.stamp
> > > ok
> > > 
> > > No warnings!  Are you doing anything different than me?
> > 
> > Almost the same. The difference is that I ran 'gclient sync'.
> > 
> > It says libwebp is at 3fe91635df8734b23f3c1b9d1f0c4fa8cfaf4e39.
> > 
> > May be that is why you aren't seeing this error?
> 
> Reproduced and fixed!  Please take a look at patch set 4.  (Obviously, it
LGTM.)

Thanks Mike! Pushing to CQ!

[commit-bot: I haz the power, 2013-10-28 21:40:29]

CQ is trying da patch. Follow status at
https://skia-tree-status.appspot.com/cq/tfarina@chromium.org/47603012/190001

[Nico, 2013-10-28 22:00:08]

(Is this gyp file used for anything? Can the warning be fixed, instead of
suppressed?)

[mtklein, 2013-10-28 22:05:05]

On 2013/10/28 22:00:08, Nico wrote:
> (Is this gyp file used for anything? Can the warning be fixed, instead of
> suppressed?)

It's used for building libwebp for Skia when we're not using the system webp
(e.g outside Chrome,Android).

The warning can be fixed by commenting out the unused array kCoeffThresh[16], or
I guess asking skal@ to do his TODO and turn it back on.

[commit-bot: I haz the power, 2013-10-28 22:05:17]

Change committed as 11990