How I fixed " Undefined symbol '___CompiledDebuggingLevel' ..."

[carlox]

For reasons too long to explain here, I often link a static library compiled with debug option to my main programs.

If I forget to switch to release mode library and I build the release configuration occurs a single linker error:

error: Undefined symbol '___CompiledDebuggingLevel' referenced in "c:\program files (x86)\national instruments\cvi2017\bin\msvc\cvistart.lib".

As far as I can understand, the debug mode library expects that someone defines the variable.
This issue should have be corrected in 2012 (CAR 372694) but it still occurs in LabWindows/CVI 2017.

With a simple additional source file, I have resolved the issue so I can safely forget 🙂 to manually switch the static library. If you have the same issue, cut & paste in a .c file and add it to your program sources.

//
// DebugLevelPatch.c
//
// A patch to really fix issue 372694
// 
// By including this file in a LabWindows CVI project, you can avoid link errors
// that may occurr when you link a "release" executable with a static library that was
// built with "debug" options.
//
// The value of this variable is related to the "Debugging Level" setting in Build Options dialog box.
// We can know its values by printing it from a normal debug executable:
// No run-time checking = 1
// Standard		= 2
// Extended             = 3
// so the natural choice for a release mode executable is 1.
//
// If this could be included in "release mode" C startup code, it would fix the problem 
// in a more elegant way.
//
#ifdef NDEBUG
int __CompiledDebuggingLevel = 1;
#endif

[CorraDIT]

Hi carlox,

thanks for your post! I'll go ahead and signal this to make sure it gets fixed, but in the mean time this is a great workaround.

Best,

CorraDIT