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Re: Static Libcurl crashes on MSVC13

From: Gisle Vanem <>
Date: Fri, 26 Feb 2016 13:17:25 +0100

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.

List admin:
Received on 2016-02-26