While building Qt (with nmake), qwebengine_convert_dict.exe crashes in the function InitializeICU(). I configured with "-noicu":

-prefix E:\Qt\5.8.0-alpha -no-openssl -commercial -no-icu -opengl dynamic -platform win32-msvc2015 -mp -nomake tests -compile-examples

so this function (or probably the program itself) should never have been called.

The last output in the command line is:

call E:\Qt\qt-everywhere-enterprise-src-5.8.0-alpha\qtwebengine\examples\webenginewidgets\spellchecker\qwebengine_convert_dict_wrapper.bat dict\en\en-US.dic debug\qtwebengine_dictionaries\en-US.bdic
[0914/143805:ERROR:icu_util.cc(188)] Invalid file descriptor to ICU data received.
[0914/143805:FATAL:icu_util.cc(307)] Check failed: result.
Backtrace:
base::debug::StackTrace::StackTrace [0x00007FF7502BC431+33] (e:\qt\qt-everywhere-enterprise-src-5.8.0-alpha\qtwebengine\src\3rdparty\chromium\base\debug\stack_trace_win.cc:215)
logging::LogMessage::~LogMessage [0x00007FF7502B5214+68] (e:\qt\qt-everywhere-enterprise-src-5.8.0-alpha\qtwebengine\src\3rdparty\chromium\base\logging.cc:520)
base::i18n::InitializeICU [0x00007FF7502A33E3+259] (e:\qt\qt-everywhere-enterprise-src-5.8.0-alpha\qtwebengine\src\3rdparty\chromium\base\i18n\icu_util.cc:320)
main [0x00007FF7502A2B1E+494]
__scrt_common_main_seh [0x00007FF7502C9B49+285] (f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:253)
BaseThreadInitThunk [0x00007FFF15308102+34]
RtlUserThreadStart [0x00007FFF1796C5B4+52]