Simple singleton pattern - Visual C++ assertion failure - visual-c++

Question

I'm recently programming a very simple logger class in Visual C++ 2010, but I have a problem. Everytime I run the program, a debug assertion failure appears.
Expression: _CrtIsValidHeapPointer(pUserData)
This is how my class looks like (basically it's only a little modified from an answer here C++ Singleton design pattern):
class Logger
{
public:
// Returns static instance of Logger.
static Logger& getInstance()
{
static Logger logger; // This is where the assertion raises.
return logger;
}
void logError(std::string errorText);
// Destructor.
~Logger();
private:
std::ofstream logFileStream;
// The constructor is private to prevent class instantiating.
Logger();
// The copy constructor and '=' operator need to be disabled.
Logger(Logger const&) { };
Logger& operator=(Logger other) { };
};
And the constructor is:
Logger::Logger()
: logFileStream(Globals::logFileName, std::ios_base::trunc)
{
// (Tries to open the file specified in Globals for (re)writing.)
}
I found out that I can solve it by using static variables or methods somehow, but I don't understand what's wrong with this code. Does anyone know, where the problem is?
EDIT: FYI, the failure raises when this code is called (for the first time):
Logger::getInstance().logError("hello");
EDIT 2: This is the definition of logFileName in Globals:
static const std::string logFileName = "errorLog.log";

Answer 1

My guess is that you're calling getInstance() from the constructor of another global variable, and encountering the infamous initialisation order fiasco - it's unspecified whether or not Globals::logFileName has been initialised before any globals in other translation units.
One fix is to use an old-school C string, which will be statically initialised before any global constructor is called:
static const char * logFileName = "errorLog.log";
Another possibility is to access it via a function:
static std::string logFileName() {return "errorLog.log";}
My favoured solution would be to remove the global instance altogether, and pass a reference to whatever needs it; but some might find that rather tedious, especially if you already have a large amount of code that uses the global.

Answer 2

C++/CLI is not standard C++ and plays by slightly different rules. Are you using C++/CLI managed code at all? (/clr compiler option?) This looks like a common problem when mixing C++ (unmanaged) code with C++/CLI (managed) code. It has to do with the way managed and unmanaged construction and destruction happens at program initialization and program exit. Removing the destructor works for me - can you do that in your Logger class?
For more details and possible workarounds:
http://www.codeproject.com/Articles/442784/Best-gotchas-of-Cplusplus-CLI
http://social.msdn.microsoft.com/Forums/vstudio/en-US/fa0e9340-619a-4b07-a86b-894358d415f6/crtisvalidheappointer-fails-on-globally-created-object-within-a-static-llibrary?forum=vcgeneral
http://forums.codeguru.com/showthread.php?534537-Memory-leaks-when-mixing-managed-amp-native-code&p=2105565