this issue has bothering me for a long time,

when compiling qt under windows with vs2013, I always get this

[1479/10504] CXX obj\src\3rdparty\chromium\base\base.tracked_objects.obj
c:\program files (x86)\microsoft visual studio 12.0\vc\include\xtree(604) : warn
ing C4702: unreachable code
c:\program files (x86)\microsoft visual studio 12.0\vc\include\xtree(604) : warn
ing C4702: unreachable code
c:\program files (x86)\microsoft visual studio 12.0\vc\include\xtree(604) : warn
ing C4702: unreachable code
[1481/10504] CXX obj\src\3rdparty\chro...eading\base.thread_id_name_manager.obj
c:\program files (x86)\microsoft visual studio 12.0\vc\include\xtree(604) : warn
ing C4702: unreachable code
c:\program files (x86)\microsoft visual studio 12.0\vc\include\xtree(604) : warn
ing C4702: unreachable code
c:\program files (x86)\microsoft visual studio 12.0\vc\include\xtree(1826) : war
ning C4702: unreachable code
[1494/10504] CXX obj\src\3rdparty\chromium\base\base.values.obj
c:\program files (x86)\microsoft visual studio 12.0\vc\include\xtree(1826) : war
ning C4702: unreachable code
[1496/10504] CXX obj\src\3rdparty\chromium\base\win\base.scoped_handle.obj
c:\program files (x86)\microsoft visual studio 12.0\vc\include\xtree(604) : warn
ing C4702: unreachable code
[1511/10504] CXX obj\src\3rdparty\chro...reading\base.sequenced_worker_pool.obj
c:\program files (x86)\microsoft visual studio 12.0\vc\include\xtree(1826) : war
ning C4702: unreachable code
c:\program files (x86)\microsoft visual studio 12.0\vc\include\xtree(1826) : war
ning C4702: unreachable code
[1752/10504] ACTION gen_asm_offsets_vp...s_obj_ffc74dcfffbd2def4866ddf9676f1282
FAILED: C:\Python27\python.exe gyp-win-tool action-wrapper environment.x86 gen_a
sm_offsets_vp8_target_copy_enc_offsets_obj_ffc74dcfffbd2def4866ddf9676f1282..rsp
..\..\..\src\3rdparty\chromium\third_party\libvpx
Unable to locate file
[1752/10504] CXX obj\src\3rdparty\chro...a\src\gpu\skia_library.SkGpuDevice.obj
ninja: build stopped: subcommand failed.
NMAKE : fatal error U1077: 'C:\Qt\qt-everywhere-opensource-src-5.4.2\qtwebengine
\src\3rdparty\ninja\ninja.exe' : return code '0x1'
Stop.
NMAKE : fatal error U1077: '"C:\Program Files (x86)\Microsoft Visual Studio 12.0
\VC\BIN\nmake.exe"' : return code '0x2'
Stop.
NMAKE : fatal error U1077: '(' : return code '0x2'
Stop.
NMAKE : fatal error U1077: 'cd' : return code '0x2'
Stop.
NMAKE : fatal error U1077: 'cd' : return code '0x2'
Stop.
NMAKE : fatal error U1077: 'cd' : return code '0x2'
Stop.

this happens when building chromium. it complains that an obj file doesn't exist:

FAILED: C:\Python27\python.exe gyp-win-tool action-wrapper environment.x86 gen_a
sm_offsets_vp8_target_copy_enc_offsets_obj_ffc74dcfffbd2def4866ddf9676f1282..rsp
..\..\..\src\3rdparty\chromium\third_party\libvpx

I can build the project chromium by itself on the same machine with the same compiler, but I can't build it as part of Qt.