Re: [patch #6448] [MSVC 7/7] Add MSVC Support

[Charles Wilson]

Peter Rosin wrote:
> That may not work, if Charles statements about dlls requiring different
> patchlevels of msvcr80 holds. But that appears to not be the case:
> 
> I created a simple dll, exporting one function doing a printf (some random
> libc function). When building this dll, MSVC8 generated a manifest, but I
> instead embedded the manifest pointing to an older msvcr80.

[snip]

> Then I created an exe using both fopen (some other libc function) and
> consuming this dll, and in that exe I embedded the generated manifest
> (i.e. version 8.0.50727.762). Looking at this exe with depends.exe
> reveals that only one msvcr80.dll is loaded. That might be a bug in
> depends.exe though.

In a non-toy application, consisting of a dozen different open-source C
libraries, thirty or more proprietary libraries comprising about 250k
lines of C++ code, and a handful of applications, we ran into
significant issues when developer A built the open source libraries with
MSVC 2005 patchlevel X, and developer B linked the application(s) using,
and where our proprietary code was compiled with, his MSVC 2005
patchlevel Y.  The apps crashed badly.  These problems went away when
everything -- including C open-source libraries -- were all compiled
with the same patchlevel compiler, with no other changes.

> Yes, it is handled by libtool. Though, libtool will currently not
> embed manifests in built dlls, only exes. Maybe dlls also need
> to have the manifest embedded, but I have not needed that yet...

VisStudio does embed manifests in the DLLs AFAICT. However, this /may/
not be necessary, and perhaps I should try turning that off.  Then, the
only items in my on-the-job work that would actually specify which
patchlevel/runtime should be loaded would be the application itself.

As long as there's no conflict (for C++) between inline code taken from
the STL headers of patchlevel X, and the non-inline code dynamically
linked at runtime from the msvcp80.dll of patchlevel Y. (Note here I'm
specifically talking about the C++ runtime, but similar
inline/vs/out-of-line concerns probably hold for the C runtime of
doffering patchlevels).

Only experimentation will tell.

--
Chuck