INFO: LNK2001 Error ATL Release Build

• Microsoft Active Template Library, versions 2.0, 2.1

SUMMARY

Microsoft Active Template Library COM AppWizard generates a release build of your project using macro _ATL_MIN_CRT. Selecting this configuration causes the C-Runtime (CRT) library startup code to not be linked into your project. If you use functions or code in your project that require the use of the C-Runtime library startup code, you may experience LNK2001 - unresolved external errors when you try to build the release version of your project.

MORE INFORMATION

You can use some C-Runtime functions without requiring the CRT startup code. Examples include the mem* functions. Other functions require the CRT startup code. CRT string comparisons for example require the startup code as the CRT initializes some tables used for comparing. Global objects that have constructors also require the startup code. In Visual C++ 5.0, statically linking the startup code adds about 25K to your image(In Visual C++ 4.2 it is about 20K).

Following are some suggestions for finding the cause of the LNK2001 errors:

• In the linker options there is an "ignore libraries" edit box. Enter Libcmt.lib into it, and build. You get several unresolved externals. This list is everything that you are using from the CRT. Look for things that you think may be pulling in the startup code and remove them if you can.
• Don't ignore Libcmt.lib, but turn on the verbose flag for the linker. From this, you can see what is triggering CRT startup code to get pulled in.