Changes to ALLOW_UNUSED to match upcoming changes to the Chromium trunk:

Changes to ALLOW_UNUSED to match upcoming changes to the Chromium trunk:
* Eliminate usage of ALLOW_UNUSED to define COMPILE_ASSERT and just use
  static_assert() in all cases now that all platforms build with C++11.
* Convert remaining uses of ALLOW_UNUSED to ALLOW_UNUSED_TYPE to match how
  Chromium will be splitting this functionality.  (In Chromium we'll have both
  ALLOW_UNUSED_TYPE and ALLOW_UNUSED_LOCAL, which have different syntax to
  enable us to use these with MSVC.)

BUG=chromium:81439
TEST=none
LOG=y
R=svenpanne@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=24344

[Peter Kasting, 2014-09-30 18:43:22]

pkasting@chromium.org changed reviewers:
+ jochen@chromium.org

[Jakob Kummerow, 2014-09-30 19:47:15]

DBC: I'm not sure V8 is ready to drop pre-C++11 support, for the benefit of
non-Chrome embedders. If we do decide to make this cut, we should announce it
broadly (and ideally with some warning / grace period) on v8-users@. In the
meantime I'd suggest to keep STATIC_ASSERT as it is.

[Peter Kasting, 2014-10-01 02:18:47]

On 2014/09/30 19:47:15, Jakob wrote:
> DBC: I'm not sure V8 is ready to drop pre-C++11 support, for the benefit of
> non-Chrome embedders. If we do decide to make this cut, we should announce it
> broadly (and ideally with some warning / grace period) on v8-users@.

Would you be willing to do that?  I'm not a V8 developer, but I think it would
be nice for V8 to follow Chromium and Blink here, or at least to evaluate what
blockers exist.

> In the
> meantime I'd suggest to keep STATIC_ASSERT as it is.

I restored its definition, updated to use the new macro name.  While I was at it
I fixed some outdated comments on it.  PTAL.

[Sven Panne, 2014-10-01 06:21:22]

svenpanne@chromium.org changed reviewers:
+ svenpanne@chromium.org

[Sven Panne, 2014-10-01 06:21:23]

LGTM. Regarding the other comments: We will not introduce some kind of grace
period for v8 and C++11, this would only complicate things because we'll diverge
from Chrome for that time. This in turn would mean that we can't simply get the
relevant Chrome changes for free. (Thanks Peter, it's great that we were not
forgotten! ;-) Keep those changes coming...)

Regarding the static_assert: I would *love* to kick out the old stuff and just
use that, but we still have NaCL bots with ancient toolchains, so we can't do it
right now. But we'll probably just switch those bots off real soon now, just use
C++11 and let the NaCL team resurrect the bots/parts of our build system with
PNaCL.

I'll land the CL for you...

[Sven Panne, 2014-10-01 06:32:17]

Committed patchset #3 (id:40001) manually as 24344 (presubmit successful).