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Re: Static Libcurl crashes on MSVC13

From: Jules van der Toorn <>
Date: Fri, 26 Feb 2016 16:13:35 +0100

Thanks for your answer. That could certainly be the case. But can you
please explain how to make that map file and how to use it?
I tried creating one using dumpbin.exe from MSVC. I included the result of
that in this email. I hope that helps.
Sorry, i never used .map files before.

2016-02-26 13:17 GMT+01:00 Gisle Vanem <>:

> Jules van der Toorn wrote:
> > Thanks for the quick answer! I don't think it's an error in my code,
> because i literally copied the code from your site,
> > the imap-fetch <> code (
> > <>), and that did work
> previously when i had the dynamic libcurl library.
> The important detail was:
> "Debug Assertion Failed! Expression: _CrtIsValidHeapPointer(pUserData)"
> It usually means you're mixing code built with different C-RunTime
> libraries.
> Like mixing debug (-MDd, -MTd) and release (-MD, -MT) objects. That could
> happen easily when you go from a dynamic use of libcurl to a static build.
> Since in a libcurl.dll it would malloc/free it's own memory. But when you
> link all statically, the linker forces only 1 'free' and 1 'malloc' in the
> resulting .exe (one can never have multiple symbols in the same PE-image).
> To figure this out, make a more detailed .map-file; add '-verbose'
> and see where malloc() and free() are really coming from.
> Good luck.
> --
> --gv
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Received on 2016-02-26