/FU (Name Forced #using File)

A compiler option that you can use as an alternative to passing a file name to #using Directive in source code.


/FU file


Specifies the metadata file to reference in this compilation.


The /FU switch takes just one file name. To specify multiple files, use /FU with each one.

If you are using C++/CLI and are referencing metadata to use the Friend Assemblies feature, you can't use /FU. You must reference the metadata in code by using #using—together with the [as friend] attribute. Friend assemblies are not supported in Visual C++ component extensions C++/CX.

For information about how to create an assembly or module for the common language runtime (CLR), see /clr (Common Language Runtime Compilation). For information about how to build in C++/CX, see Building apps and libraries.

To set this compiler option in the Visual Studio development environment

  1. Open the project's Property Pages dialog box. For details, see Set C++ compiler and build properties in Visual Studio.

  2. Select the Configuration Properties > C/C++ > Advanced property page.

  3. Modify the Force #using property.

To set this compiler option programmatically

See also

Output-File (/F) Options
MSVC Compiler Options
MSVC Compiler Command-Line Syntax