Forward declaration of array of QStrings leads to segmentation fault

Question

In this code I have two forward declarations, a bool array and a QString array in namesace NLog.

bool works. QString produces a segmentation fault.

Header:

class Log : public QObject
{

    explicit Log();
public:
    enum Facility
    {
      third_party_fac,
      test_fac,
      __facility_last_element
    };
    enum Severity
    {
      debug_sev,
      warning_sev,
      critical_sev,
      fatal_sev,
      __severity_last_element
    };
};
namespace NLog
{
    extern bool logging_enabled[Log::__facility_last_element][Log::__severity_last_element];
    extern QString severity_name[Log::__severity_last_element];
};
class LogStaticInitiallizer
{
public:
    LogStaticInitiallizer();
};
static LogStaticInitiallizer initiallizer=LogStaticInitiallizer();

Source:

QString NLog::severity_name[Log::__severity_last_element];
bool NLog::logging_enabled[Log::__facility_last_element][Log::__severity_last_element];
using NLog::logging_enabled;
using NLog::severity_name;
LogStaticInitiallizer::LogStaticInitiallizer()
{
    qDebug()<<"0";
    qDebug()<<logging_enabled[0][0];
    qDebug()<<severity_name[0];
    qDebug()<<"1";
}

it produces

0

false

and crashes at QString trace

Answer 1

As Piotr S. said, the problem is that LogStaticInitiallizer constructor is called before its initialization in source file.

Also, there is an unrelated to main problem with reserved identifiers starting with __. See What are the rules about using an underscore in a C++ identifier?