QString::QString (const char * str) and QString::fromStdString (std::string) gives crash

I am facing below issue in Qt 5.11.2 and Qt 5.12.0 but not before that. 

While creating QString( const char* str ) via c_str() function gives crash to the application. Hence not able to use any function which returns (const char * ) (ex. c_str() ). I know similar issue QTBUG-21365 reported and closed as not reproducing in Linux. But I am pretty much sure that if you setup as I suggested on windows x86 system , will definitely reproduce. 

Also, while using substitute of above method that creating QString::fromStdString(std::string) gives crash to the application. Hence request to you please try from your side and provide the fix for both the API as QString is very vastly use in Qt applications.