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Customize C++ builds

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For C++ projects, the custom .targets and .props files can't be used in the same way to override default settings. This article describes a different way of customizing the build that works for C++ builds.

The file Directory.Build.props that is useful for customizing .NET projects is imported by Microsoft.Common.props, which is imported in Microsoft.Cpp.Default.props, while most of the defaults are defined in Microsoft.Cpp.props, and for many properties a "if not yet defined" condition can't be used, as the property is already defined, but the default needs to be different for particular project properties defined in PropertyGroup with Label="Configuration" (see .vcxproj and .props file structure).

For C++ projects, you can use the following properties to specify .props file(s) to be automatically imported before/after Microsoft.Cpp.* files:

  • ForceImportAfterCppDefaultProps
  • ForceImportBeforeCppProps
  • ForceImportAfterCppProps
  • ForceImportBeforeCppTargets
  • ForceImportAfterCppTargets

To customize the default values of properties for all C++ builds, create another .props file (say, MyProps.props), and define the ForceImportAfterCppProps property in Directory.Build.props pointing to it:

<PropertyGroup>
  <ForceImportAfterCppProps>$(MsbuildThisFileDirectory)\MyProps.props</ForceImportAfterCppProps>
</PropertyGroup>

MyProps.props will be automatically imported at the very end of Microsoft.Cpp.props.

Customize all C++ builds

Customizing the Visual Studio installation isn't recommended, since it's not easy to keep track of such customizations, but if you're extending Visual Studio to customize C++ builds for a particular platform, you can create .targets files for each platform and place them in the appropriate import folders for those platforms as part of a Visual Studio extension.

The .targets file for the Win32 platform, Microsoft.Cpp.Win32.targets, contains the following Import element:

<Import Project="$(VCTargetsPath)\Platforms\Win32\ImportBefore\*.targets"
        Condition="Exists('$(VCTargetsPath)\Platforms\Win32\ImportBefore')"
/>

There's a similar element near the end of the same file:

<Import Project="$(VCTargetsPath)\Platforms\Win32\ImportAfter\*.targets"
        Condition="Exists('$(VCTargetsPath)\Platforms\Win32\ImportAfter')"
/>

Similar import elements exist for other target platforms in *%ProgramFiles32%\MSBuild\Microsoft.Cpp\v{version}\Platforms*.

Once you place the .targets file in the appropriate ImportAfter folder according to the platform, MSBuild imports your file into every C++ build for that platform. You can put multiple .targets files there, if needed.

Using Visual Studio Extensibility, further customizations are possible, such as defining a new platform. For more information, see C++ project extensibility.

Specify a custom import on the command line

For custom .targets that you want to include for a specific build of a C++ project, set one or both of the properties ForceImportBeforeCppTargets and ForceImportAfterCppTargets on the command line.

msbuild /p:ForceImportBeforeCppTargets="C:\build\config\Custom.Before.Microsoft.Cpp.Targets" MyCppProject.vcxproj

For a global setting (to affect, say, all C++ builds for a platform on a build server), there are two methods. First, you can set these properties using a system environment variable that is always set. This technique works because MSBuild always reads the environment and creates (or overrides) properties for all the environment variables.

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