Suppress VS 2015 pointer truncation warning.

Suppress VS 2015 pointer truncation warning.

Use #pragma suppress to make the warnig disabling more compact.
Don't disable the old 4311 warning because this only applies with /Wp64
which is deprecated and not used.

R=cpu@chromium.org
BUG=440500
Committed: https://crrev.com/5f37aa494a8ef269d8033614a05c074f79cc1919
Cr-Commit-Position: refs/heads/master@{#325284}

[Will Harris, 2015-04-15 00:10:51]

hmm cool I was not aware of #pragma warning suppress! :)

[cpu_(ooo_6.6-7.5), 2015-04-15 18:06:50]

lgtm

[cpu_(ooo_6.6-7.5), 2015-04-15 18:06:53]

The CQ bit was checked by cpu@chromium.org

[commit-bot: I haz the power, 2015-04-15 18:07:19]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1091433002/1

[commit-bot: I haz the power, 2015-04-15 19:08:39]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-15 19:09:31]

Patchset 1 (id:??) landed as
https://crrev.com/5f37aa494a8ef269d8033614a05c074f79cc1919
Cr-Commit-Position: refs/heads/master@{#325284}

[scottmg, 2015-04-28 20:29:13]

2015 final rc seems to put pragma suppress back to its
almost-useless-next-line-only rather than next-statement behaviour.

[13053->1/13087 ~33] CXX obj\base\win\base_static_win64.pe_image.obj
FAILED: ninja -t msvc -e environment.x64 -- "C:\Program Files (x86)\Microsoft
Visual Studio 14.0\VC\bin\amd64\cl.exe" /nologo /showIncludes /FC
@obj\base\win\base_static_win64.pe_image.obj.rsp /c ..\..\base\win\pe_image.cc
/Foobj\base\win\base_static_win64.pe_image.obj
/Fdobj\base\base_static_win64.cc.pdb
d:\src\cr2\src\base\win\pe_image.cc(574): error C2220: warning treated as error
- no 'object' file generated
d:\src\cr2\src\base\win\pe_image.cc(574): warning C4311: 'reinterpret_cast':
pointer truncation from 'LPVOID' to 'DWORD'
d:\src\cr2\src\base\win\pe_image.cc(574): warning C4302: 'reinterpret_cast':
truncation from 'LPVOID' to 'DWORD'
d:\src\cr2\src\base\win\pe_image.cc(576): warning C4311: 'reinterpret_cast':
pointer truncation from 'PVOID' to 'DWORD'
d:\src\cr2\src\base\win\pe_image.cc(576): warning C4302: 'reinterpret_cast':
truncation from 'PVOID' to 'DWORD'

To suppress 4302 in this code it has to be

  // These casts generate warnings because they are 32 bit specific.
  // Don't follow the virtual RVAToAddr, use the one on the base.
#pragma warning(suppress : 4302) // pointer truncation
  DWORD offset_within_section = reinterpret_cast<DWORD>(address) -
                                    reinterpret_cast<DWORD>(PEImage::RVAToAddr(
#pragma warning(suppress : 4302) // pointer truncation
                                        section_header->VirtualAddress));


(not before the comment either!) so I'm back to dis-recommending suppress as I
did for 2013.

[Will Harris, 2015-04-28 20:30:55]

wow that's crazy, can we ask MS to change this behavior?

[brucedawson, 2015-04-28 20:32:35]

That is crazy. It also seems bizarre that the behavior would have changed
between the two RC versions. And yet, this fix did work, briefly.