Disable kSSizeMaxConst COMPILE_ASSERT() for Android / Mac / IOS

Disable kSSizeMaxConst COMPILE_ASSERT() for Android / Mac / IOS

The kSSizeMaxConst COMPILE_ASSERT() was previously disabled for clang only, due
to clang giving a build error on Android / Mac / IOS. gcc is affected by the
same problem so this CL disables the COMPILE_ASSERT() for Android / Mac / IOS
platforms, instead of doing it for a specific compiler.

The reason why this COMPILE_ASSERT() does not build on those platforms is that
static_assert only works with compile-time constants, but mac uses libstdc++4.2
and android uses stlport, which both don't mark numeric_limits::max() as
constexpr.

R=Nico

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=239352

[Nico, 2013-12-06 21:23:35]

This looks wrong. It's failing with clang because we use libstdc++ 4.2 with it
on mac, and numeric_limits::max() isn't marked constexpr there. Is it not
constexpr in libstdc++4.7 either?

[Inactive, 2013-12-06 21:33:42]

On 2013/12/06 21:23:35, Nico wrote:
> This looks wrong. It's failing with clang because we use libstdc++ 4.2 with it
> on mac, and numeric_limits::max() isn't marked constexpr there. Is it not
> constexpr in libstdc++4.7 either?

Here is the error I get:
FAILED:
/home/chris/devel/internal-trunk/trunk/src/third_party/android_tools/ndk//toolchains/arm-linux-androideabi-4.7/prebuilt/linux-x86_64/bin/arm-linux-androideabi-g++
-MMD -MF obj/base/strings/base.safe_sprintf.o.d -DANGLE_DX11
-D_FILE_OFFSET_BITS=64 -DNO_TCMALLOC -DDISABLE_NACL -DCHROMIUM_BUILD
-DUSE_LIBJPEG_TURBO=1 -DENABLE_WEBRTC=1 -DUSE_PROPRIETARY_CODECS
-DENABLE_CONFIGURATION_POLICY -DDISCARDABLE_MEMORY_ALWAYS_SUPPORTED_NATIVELY
-DSYSTEM_NATIVELY_SIGNALS_MEMORY_PRESSURE -DUSE_OPENSSL=1 -DENABLE_EGLIMAGE=1
-DENABLE_AUTOFILL_DIALOG=1 -DCLD_VERSION=1 -DENABLE_PRINTING=1
-DENABLE_MANAGED_USERS=1 -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS
-DBASE_IMPLEMENTATION -DANDROID -D__GNU_SOURCE=1 -DUSE_STLPORT=1
-D_STLP_USE_PTR_SPECIALIZATIONS=1 '-DCHROME_BUILD_ID=""' -DHAVE_SYS_UIO_H
-DNDEBUG -DOFFICIAL_BUILD -DNVALGRIND -DDYNAMIC_ANNOTATIONS_ENABLED=0
-D_FORTIFY_SOURCE=2 -Igen/base
-I../../third_party/android_tools/ndk/sources/android/cpufeatures -I../..
-fstack-protector --param=ssp-buffer-size=4 -Werror -fno-exceptions
-fno-strict-aliasing -Wall -Wno-unused-parameter -Wno-missing-field-initializers
-fvisibility=hidden -pipe -fPIC -march=armv7-a -mtune=cortex-a8 -mfpu=vfpv3-d16
-mfloat-abi=softfp -mthumb -fno-tree-sra -fuse-ld=gold -Wno-psabi
-mthumb-interwork -ffunction-sections -funwind-tables -g -fstack-protector
-fno-short-enums -finline-limit=64 -Wa,--noexecstack
--sysroot=/home/chris/devel/internal-trunk/trunk/src/third_party/android_tools/ndk//platforms/android-14/arch-arm
-I/home/chris/devel/internal-trunk/trunk/src/third_party/android_tools/ndk//sources/cxx-stl/stlport/stlport
-Os -fno-ident -fdata-sections -ffunction-sections -fomit-frame-pointer
-std=gnu++11 -Wno-sign-compare -fno-rtti -fno-threadsafe-statics
-fvisibility-inlines-hidden -Wno-abi  -c ../../base/strings/safe_sprintf.cc -o
obj/base/strings/base.safe_sprintf.o
../../base/strings/safe_sprintf.cc: In constructor
'base::strings::{anonymous}::Buffer::Buffer(char*, size_t)':
../../base/strings/safe_sprintf.cc:115:5: error: call to non-constexpr function
'static _Int std::priv::_Integer_limits<_Int, __imin, __imax, __idigits,
__ismod>::max() [with _Int = long int; _Int __imin = -2147483648l; _Int __imax =
2147483647l; int __idigits = -1; bool __ismod = true]'
../../base/strings/safe_sprintf.cc:115:5: error: call to non-constexpr function
'static _Int std::priv::_Integer_limits<_Int, __imin, __imax, __idigits,
__ismod>::max() [with _Int = long int; _Int __imin = -2147483648l; _Int __imax =
2147483647l; int __idigits = -1; bool __ismod = true]'
../../base/strings/safe_sprintf.cc:115:5: note: in template argument for type
'bool' 
../../base/strings/safe_sprintf.cc:116:61: error: invalid type in declaration
before ';' token
[1393/7919] CXX obj/base/strings/base.string16.o
ninja: build stopped: subcommand failed.

This is with arm-linux-androideabi-4.7 toolchain of Android NDK. No issue with
gcc 4.7 on Linux desktop though.

[Nico, 2013-12-06 21:57:11]

Oh, that's probably because Android builds with stlport which also doesn't have
a constexpr max(). So !defined(OS_MAC) && !defined(OS_ANDROID) plus a comment
that explains this is probably what you want.

[Inactive, 2013-12-06 22:14:45]

On 2013/12/06 21:57:11, Nico wrote:
> Oh, that's probably because Android builds with stlport which also doesn't
have
> a constexpr max(). So !defined(OS_MAC) && !defined(OS_ANDROID) plus a comment
> that explains this is probably what you want.

Done.

[Nico, 2013-12-06 22:17:05]

Can you please update the comment with the actual reason, instead of "something
doesn't work"? Also in the CL description.

(the reason is that static_assert only works with compile-time constants, but
mac uses libstdc++4.2 and android uses stlport, which both don't mark
numeric_limits::max() as constexpr)

[Inactive, 2013-12-06 22:18:10]

https://codereview.chromium.org/98403005/diff/20001/base/strings/safe_sprintf.cc
File base/strings/safe_sprintf.cc (right):

https://codereview.chromium.org/98403005/diff/20001/base/strings/safe_sprintf...
base/strings/safe_sprintf.cc:115: COMPILE_ASSERT(kSSizeMaxConst ==
std::numeric_limits<ssize_t>::max(),
Note that on Linux desktop, gcc does complain about comparison between signed
and unsigned integers though :(

[Nico, 2013-12-06 22:21:45]

https://codereview.chromium.org/98403005/diff/20001/base/strings/safe_sprintf.cc
File base/strings/safe_sprintf.cc (right):

https://codereview.chromium.org/98403005/diff/20001/base/strings/safe_sprintf...
base/strings/safe_sprintf.cc:115: COMPILE_ASSERT(kSSizeMaxConst ==
std::numeric_limits<ssize_t>::max(),
On 2013/12/06 22:18:10, Chris Dumez wrote:
> Note that on Linux desktop, gcc does complain about comparison between signed
> and unsigned integers though :(

It should be safe to cast std::numeric_limits<ssize_t>::max() to size_t, no?

[Inactive, 2013-12-06 22:37:17]

On 2013/12/06 22:21:45, Nico wrote:
>
https://codereview.chromium.org/98403005/diff/20001/base/strings/safe_sprintf.cc
> File base/strings/safe_sprintf.cc (right):
> 
>
https://codereview.chromium.org/98403005/diff/20001/base/strings/safe_sprintf...
> base/strings/safe_sprintf.cc:115: COMPILE_ASSERT(kSSizeMaxConst ==
> std::numeric_limits<ssize_t>::max(),
> On 2013/12/06 22:18:10, Chris Dumez wrote:
> > Note that on Linux desktop, gcc does complain about comparison between
signed
> > and unsigned integers though :(
> 
> It should be safe to cast std::numeric_limits<ssize_t>::max() to size_t, no?

I believe so since we know the value is not negative. It seems to build fine
also with gcc.

I updated the CL accordingly.

[Nico, 2013-12-06 22:40:12]

lgtm if the trybots are happy :-)

[commit-bot: I haz the power, 2013-12-07 02:15:24]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/ch.dumez@samsung.com/98403005/40001

[commit-bot: I haz the power, 2013-12-07 22:11:06]

Change committed as 239352