Can C++ libraries compiled with VC10 (sp1) be link

问题:

The question says it all.

I understand that VC11 is currently only in beta, but what I'm asking is:

1. experience with trying to link with a closed source (widely used if possible) library compiled with vc10
2. specifications from Microsoft saying explicitely if yes or no the vc11 will be able to link with vc10 libraries.

I'm talking about C++ case only.

回答1:

You may want to read this answer for the case of dynamic linking.

Regarding static linking, I think you can't safely link C++ libraries written with VCx with code compiled with VCy. For example, STL containers implementations change from version to version (and even within the same version, there are changes between debug and release mode, and settings like _HAS_ITERATOR_DEBUGGING, etc.).

Quoting VC++ STL maintainer:

The STL never has and never will guarantee binary compatibility between different major versions. We're enforcing this with linker errors when mixing object files/static libraries compiled with different major versions that are both VC10+ [...]

回答2:

That's a resounding no! Every major release of VS has a new version of the dynamic CRT, names are msvcr90.dll for VS2008, msvcr100.dll for VS2010, msvcr110.dll for VS11.

Using the dynamic CRT (/MD compile option) is important when you return C++ objects like std::string from an exported function, or otherwise return any pointer that needs to be deleted by the client code. That can only work properly when the client code is using the exact same version of the CRT as the DLL. Implicit is that this won't be the case when these chunks of code each have their own dependency on a msvcrXXX.dll version, they'll inevitably have incompatible CRT versions that don't share the same heap allocator.

You can write DLLs that are safe to use with any CRT version but that requires carefully crafting the API so that these dependencies do not exist. The COM Automation model is an example of that.

回答3:

For dynamic libraries, there should be no problem, as they follow well-defined ABIs. You can link to dll's from any compiler, any time.

Static libraries are trickier. As far as I know, Microsoft has never guaranteed cross-compiler compatibility for those. In particular, features such as link-time code generation have been known to break compatibility between earlier releases. .lib files do not have a single well-defined format like DLLs do.

It might work, because Microsoft rarely breaks compatibility unless they have to, but as far as I know, it is not guaranteed.

Of course, if the actual functions and types exposed by the DLLs don't match up, you'll run into problems.

In VC11, the sizes of almost all standard library data structures have been changed (Microsoft finally employs the empty base class optimization, effectively reducing the size of all containers which use the default allocator.), so trying to pass a std::string from a DLL compiled with VC10 into a module compiled by VC11 will certainly break.

回答4:

I don't see any reason why they could be incompatible. No matter what C++ compiler you have used to produce LIB files as soon as they follow format specification. You could check this question if you are interested in details of format.