CODEWITHSUNDEEP
c++cvisual-c++
user180247
user180247

Reputation:

Are compiled .lib files interchangeable for different versions of Microsoft Visual C++?

Some projects provide a single set of "Windows" binaries for C (and possible C++ - not sure) libraries. For example, see the links on the right side of this libxml-related page.

I'm pretty sure there's no way to convert between VC++ .lib files and MinGW GCC .a files, so calling them "Windows" rather than "Microsoft" binaries seems a tad misleading. But I'm also surprised that there's no apparent need for different binaries for different VC++ versions.

I seem to remember, many years ago, having problems writing plugins for tracker-style music program (Jeskola Buzz) because that program was using VC++6, and I had upgraded to VC++7. I don't remember the exact issue - it may have been partly DLL related, but I know those don't need to care about VC++ version. I think the issue related to the .lib files provided and maybe also to the runtime libraries that they linked to. It was a long while ago, though, so it's all a bit vague.

Anyway, can libraries compiled by one version of MS VC++ be linked into projects built with another version? What limitations apply, if any?

I'm interested in both C and C++ libraries, which will be called from C++ projects (I rarely use C, except for C libraries called from C++).

Upvotes: 9

Views: 2321

Answers (1)

Abyx
Abyx

Reputation: 12918

The MS COFF format (.lib, .obj, etc) is the same for all VC++ versions and even for other languages.

The problem is that .obj files depend on other .obj (.lib) files.
For C++ code, there is a happy chance that code won't compile with new version of VC++ standard library implementation. For example, an old version of CRT used extern "C++" void internal_foo(int), and newer CRT uses extern "C++" void internal_foo(int, int), so linker will fail with "unresolved external symbol" error. For C code, there is a chance that code will compile, because for extern "C", symbol names doesn't encode whole signature. But at runtime application will crash after this function will be called.
The same thing can happen if layout of some data structure will change, linker will not detect it.

Upvotes: 4

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