Difficulty using <Import> to modularize a Visual Studio project file - visual-studio

Question

I'm attempting to modularize a Visual Studio project file, but it's not working. This is for Visual Studio 2008 with .Net 3.5.
Shown below, the first example works, but the second one does not. How can I make it work..?
I'm new to this topic and probably missing something. I first became aware of it while reading a 3rd-party blog, and then found it in the documentation too. I've googled for more help, but there's too much information for me to find a relevant answer.
The main project file:
...
<!-- main project file -->
<Import Project="$(MSBuildToolsPath)\Microsoft.VisualBasic.targets" />
<Target Name="AfterBuild">
<Message Text="This is a message from the *.vbproj file."/> ... this works
</Target>
</Project>
...but if <Import> is used, with the same <Target> and <Message> in the imported file, it doesn't work. MSBuild seems to process everything correctly, but nothing happens...
The main project file:
...
<Import Project="$(MSBuildToolsPath)\Microsoft.VisualBasic.targets" />
<Import Project="$(MSBuildProjectDirectory)\CustomBuildEvents.targets" /> ... new tag
<Target Name="AfterBuild">
<Message Text="This is a message from the *.vbproj file."/> ... this still works
</Target>
</Project>
The imported targets file:
<?xml version="1.0" encoding="utf-8"?>
<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
<Target Name="AfterBuild">
<Message Text="Hello from the imported file." Importance ="high"/> ... doesn't work
</Target>
</Project>
And the build output, with Verbosity set to Diagnostic:
### Halfway through the output, this is the only mention of the imported file. ###
None
CustomBuildEvents.targets ... custom file
My Project\Application.myapp
My Project\Settings.settings
### And then at the end, no mention of the imported file or its message. ###
Done building target "CoreBuild" in project "MsBuildCustomTargetTester.vbproj".
Target "AfterBuild" in file "C:\Visual Studio 2008\Solutions\MsBuildCustomTargetTester\MsBuildCustomTargetTester\MsBuildCustomTargetTester.vbproj":
Task "Message"
Hello from the *.vbproj file. ... message from main file
Done executing task "Message".
Done building target "AfterBuild" in project "MsBuildCustomTargetTester.vbproj".
Target "Build" in file "c:\WINDOWS\Microsoft.NET\Framework\v3.5\Microsoft.Common.targets":
Building target "Build" completely.
No input files were specified.
Done building target "Build" in project "MsBuildCustomTargetTester.vbproj".
Done building project "MsBuildCustomTargetTester.vbproj".
Project Performance Summary:
109 ms C:\Visual Studio 2008\Solutions\MsBuildCustomTargetTester\MsBuildCustomTargetTester\MsBuildCustomTargetTester.vbproj 1 calls

Answer 1

The problem with AfterBuild is that it can only be defined once. So if you import it and then later in the project file define it again, the last definition wins and becomes the only definition.
To solve this you need to use the more advanced way to register events. Given that you are using Visual Studio 2008 (WHY?!), you need to use the more advanced syntax for your custom targets files:
<Project>
<!--
Redefines the original build order, includes the standard targets and
adds your new custom target to the end of the list.
-->
<PropertyGroup>
<BuildDependsOn>
$(BuildDependsOn);
CustomTarget
</BuildDependsOn>
</PropertyGroup>
<CustomTarget>
<!-- Imported after Build -->
<Message Text="Hello from the imported file." Importance ="high"/>
</CustomTarget>
</Project>
There are other ways to do this which were introduced in MsBuild 4 with the BeforeTargets and AfterTargets attributes on any target, but If I'm remembering correctly the above syntax should also work with the version of MsBuild that ships with Visual Studio 2008.
See also:
What is the difference between 'DependsOnTargets' and 'AfterTargets'?
https://blogs.msdn.microsoft.com/msbuild/2006/02/10/how-to-add-custom-process-at-specific-points-during-build-method-2/