compiler-error-c2813.md

description	title	ms.date	f1_keywords	helpviewer_keywords	ms.assetid
Learn more about: Compiler Error C2813	Compiler Error C2813	11/04/2016	C2813	C2813	6cf2135f-7b82-42d1-909a-5e864308a09c

Compiler Error C2813

#import is not supported with /MP

C2813 is emitted if in a compiler command you specify the /MP compiler option and two or more files to compile, and one or more of the files contains the#import preprocessor directive. The #import directive generates C++ classes from the types in the specified type library, and then writes those classes to two header files. The #import directive is not supported because if multiple compilation units import the same type library, those units conflict when they try to write the same header files at the same time.

This compiler error and the /MP compiler option are new in Visual Studio 2008.

Example

The following sample generates C2813. The command line in the "compile with:" comment indicates to the compiler to use the /MP and /c compiler options to compile several files. At least one of the files contains the #import directive. We use the same file twice for the sake of testing this example.

// C2813.cpp
// compile with: /MP /c C2813.cpp C2813.cpp
#import "C:\windows\system32\stdole2.tlb"   // C2813
int main()
{
}