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Regarding this Stack Overflow question: How bad is it to mix and match Visual C++ runtime DLL files in one process?

I know I can expect heap corruption by using a different version of MSVCR at runtime.

But let's imagine the following situation that can't work:

  • libA is a shared library which links against MSVCR71
  • Exe is my program that links against libA and MSVCR100

I have then the following dependency scheme:

Exe +--> libA ---> MSVCR71
    +--> MSVCR100

THAT is, the thing I KNOW I shouldn't do!

BUT what if now, I compile libA as a static library with whatever Visual Studio that uses MSVCR71 and I compile my program, the Exe, with libA using a Visual Studio that uses MSCVR100.

I will then have the following scheme:

Exe(lib A included) ---> MSVCR100

Will the program (including the static lib) be linked well against MSVC100 without any problem? Or can I expect an undefined behaviour because the header of the STL are susceptible to change between the MSVCR71 and the MSVC100?

Peter Mortensen
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dkg
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    A library does not "link" with anything. It was simply compiled with outdated #include files. Might work, you won't know until you try. If you have source so you can recompile then there's no point in wasting your time on trying. – Hans Passant Jan 12 '16 at 13:10
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    It sounds like you are mixing STL and standard library types between the 71 and 100 versions of the runtime - don't expect that to work. If your libraries don't share any standard library types and services (e.g. memory allocations), then you should be ok. If you have the code, save yourself the pain and just recompile everything to a single target runtime. – Niall Jan 12 '16 at 13:16

1 Answers1

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I finally found the answer on MSDN...

I quote (Visual C++ change history 2003 - 2015):

To avoid run-time errors that are difficult to detect and diagnose, we recommend that you never statically link to binaries that were compiled by using different versions of the compiler. Also, when you upgrade an EXE or DLL project, make sure to upgrade the libraries that it links to. If you're using CRT (C Runtime) or STL (Standard Template Library) types, don't pass them between binaries (including DLLs) that were compiled by using different versions of the compiler.

Hence, better recompile everything with the same compiler, to be sure.

Peter Mortensen
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dkg
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