How to: Extend the Visual Studio build process

The Visual Studio build process is defined by a series of MSBuild .targets files that are imported into your project file. One of these imported files, Microsoft.Common.targets, can be extended to allow you to run custom tasks at several points in the build process. This article explains two methods you can use to extend the Visual Studio build process:

  • Overriding specific predefined targets defined in Microsoft.Common.targets.

  • Overriding the "DependsOn" properties defined in Microsoft.Common.targets.

Override predefined targets

The Microsoft.Common.targets file contains a set of predefined empty targets that is called before and after some of the major targets in the build process. For example, MSBuild calls the BeforeBuild target before the main CoreBuild target and the AfterBuild target after the CoreBuild target. By default, the empty targets in Microsoft.Common.targets do nothing, but you can override their default behavior by defining the targets you want in a project file that imports Microsoft.Common.targets. By overriding the predefined targets, you can use MSBuild tasks to give you more control over the build process.

To override a predefined target

  1. Identify a predefined target in Microsoft.Common.targets that you want to override. See the table below for the complete list of targets that you can safely override.

  2. Define the target or targets at the end of your project file, immediately before the </Project> tag. For example:

    <Project>
        ...
        <Target Name="BeforeBuild">
            <!-- Insert tasks to run before build here -->
        </Target>
        <Target Name="AfterBuild">
            <!-- Insert tasks to run after build here -->
        </Target>
    </Project>
    
  3. Build the project file.

The following table shows all of the targets in Microsoft.Common.targets that you can safely override.

Target name Description
BeforeCompile, AfterCompile Tasks that are inserted in one of these targets run before or after core compilation is done. Most customizations are done in one of these two targets.
BeforeBuild, AfterBuild Tasks that are inserted in one of these targets will run before or after everything else in the build. Note: The BeforeBuild and AfterBuild targets are already defined in comments at the end of most project files, allowing you to easily add pre- and post-build events to your project file.
BeforeRebuild, AfterRebuild Tasks that are inserted in one of these targets run before or after the core rebuild functionality is invoked. The order of target execution in Microsoft.Common.targets is: BeforeRebuild, Clean, Build, and then AfterRebuild.
BeforeClean, AfterClean Tasks that are inserted in one of these targets run before or after the core clean functionality is invoked.
BeforePublish, AfterPublish Tasks that are inserted in one of these targets run before or after the core publish functionality is invoked.
BeforeResolveReferences, AfterResolveReferences Tasks that are inserted in one of these targets run before or after assembly references are resolved.
BeforeResGen, AfterResGen Tasks that are inserted in one of these targets run before or after resources are generated.

Override DependsOn properties

Overriding predefined targets is an easy way to extend the build process, but, because MSBuild evaluates the definition of targets sequentially, there is no way to prevent another project that imports your project from overriding the targets you already have overridden. So, for example, the last AfterBuild target defined in the project file, after all other projects have been imported, will be the one that is used during the build.

You can guard against unintended overrides of targets by overriding the DependsOn properties that are used in DependsOnTargets attributes throughout the Microsoft.Common.targets file. For example, the Build target contains a DependsOnTargets attribute value of "$(BuildDependsOn)". Consider:

<Target Name="Build" DependsOnTargets="$(BuildDependsOn)"/>

This piece of XML indicates that before the Build target can run, all the targets specified in the BuildDependsOn property must run first. The BuildDependsOn property is defined as:

<PropertyGroup>
    <BuildDependsOn>
        BeforeBuild;
        CoreBuild;
        AfterBuild
    </BuildDependsOn>
</PropertyGroup>

You can override this property value by declaring another property named BuildDependsOn at the end of your project file. By including the previous BuildDependsOn property in the new property, you can add new targets to the beginning and end of the target list. For example:

<PropertyGroup>
    <BuildDependsOn>
        MyCustomTarget1;
        $(BuildDependsOn);
        MyCustomTarget2
    </BuildDependsOn>
</PropertyGroup>

<Target Name="MyCustomTarget1">
    <Message Text="Running MyCustomTarget1..."/>
</Target>
<Target Name="MyCustomTarget2">
    <Message Text="Running MyCustomTarget2..."/>
</Target>

Projects that import your project files can override these properties without overwriting the customizations that you have made.

To override a DependsOn property

  1. Identify a predefined DependsOn property in Microsoft.Common.targets that you want to override. See the table below for a list of the commonly overridden DependsOn properties.

  2. Define another instance of the property or properties at the end of your project file. Include the original property, for example $(BuildDependsOn), in the new property.

  3. Define your custom targets before or after the property definition.

  4. Build the project file.

Commonly overridden DependsOn properties

Property name Description
BuildDependsOn The property to override if you want to insert custom targets before or after the entire build process.
CleanDependsOn The property to override if you want to clean up output from your custom build process.
CompileDependsOn The property to override if you want to insert custom processes before or after the compilation step.

See also