What are the porting issues going from VC8 (VS2005) to VC9 (VS2008)?

Answer 1

That's certainly an interesting problem. I don't have a solution other than perhaps to change the design so that there is no dependence on undefined behavior of the order or link/dll startup. Have you considered linking with the older linker? (or whatever the VS.NET term is)

Because the behavior of your variable and allocator relied on some (unknown at the time) arbitrary order of startup I would probably fix that so that it is not an issue in the future. I guess you are really asking if anyone knows how to do some voodoo in VC9 to make the problem disappear. I am interested in hearing it as well.

Answer 2

Is there some way to force the construction of a global object prior to loading DLLs?

How about the DELAYLOAD option? So that DLLs aren't loaded until their first call?

Answer 3

How about this,

1. Make your main program a DLL too, call it main.dll, linked to all the other ones, and export the main function as say, mainEntry(). Remove the global variable.
2. Create a new main exe which has the global variable and its initialization, but doesn't link statically to any of the other application DLLs (except for the allocator stuff).
3. This new main.exe then dynamically loads the main.dll using LoadLibrary(), then uses GetProcAddress to call mainEntry().

Answer 4

That is a tough problem, mostly because you've inherited a design that's inherently dangerous because you're not supposed to rely on the initialization order of global variables.

It sounds like something you could try to work around by replacing the global variable with a singleton that other functions retrieve by calling a global function or method that returns a pointer to the singleton object. If the object exists at the time of the call, the function returns a pointer to it. Otherwise, it allocates a new one and returns a pointer to the newly allocated object.

The problem, of course, is that I can't think of a singleton implementation that would avoid the problem you're describing. Maybe this discussion would be useful: http://www.oneunified.net/blog/Personal/SoftwareDevelopment/CPP/Singleton.article