使用MSBuild Message元素无法在构建输出中显示消息的问题

问题现象 #

使用MSBuild的<Message>元素在构建输出窗口展示消息，无论调整详细级别都看不到内容，但<Exec>执行的echo语句能正常显示。

项目配置 #

<Project Sdk="Microsoft.NET.Sdk">

    <PropertyGroup>
        <OutputType>WinExe</OutputType>
        <TargetFramework>net8.0-windows</TargetFramework>
        <Nullable>enable</Nullable>
        <ImplicitUsings>enable</ImplicitUsings>
        <UseWPF>true</UseWPF>
        <Deterministic>false</Deterministic>
        <GenerateAssemblyInfo>false</GenerateAssemblyInfo>
    </PropertyGroup>
    
    <Target Name="PostBuild" AfterTargets="PostBuildEvent">
      <Exec Command="echo hello world" />
    </Target>

    <Target Name="AfterBuild">
        <Message Text="Build completed successfully!" Importance="high" />
    </Target>
    
</Project>

构建日志 #

Rebuild started at 11:49 AM...
1>------ Rebuild All started: Project: WpfApp1, Configuration: Debug Any CPU ------
Restored C:\Users\user1\source\repos\PRACTICE\WpfApp1\WpfApp1\WpfApp1.csproj (in 2 ms).
1>WpfApp1 -> C:\Users\user1\source\repos\PRACTICE\WpfApp1\WpfApp1\bin\Debug\net8.0-windows\WpfApp1.dll
1>hello world
========== Rebuild All: 1 succeeded, 0 failed, 0 skipped ==========
========== Rebuild completed at 11:49 AM and took 01.408 seconds ==========

问题原因 #

.NET SDK风格项目中，自定义<Target>必须通过AfterTargets或BeforeTargets明确指定触发时机，否则不会自动执行。你的PostBuild目标因为设置了AfterTargets="PostBuildEvent"，能在对应阶段触发；而AfterBuild目标未配置触发条件，MSBuild不会主动运行它，导致<Message>内容无法输出。

解决方案 #

修改AfterBuild目标，添加AfterTargets="Build"属性，让它在Build目标完成后触发：

<Target Name="AfterBuild" AfterTargets="Build">
    <Message Text="Build completed successfully!" Importance="high" />
</Target>

若需在Rebuild操作后也触发，可指定AfterTargets="Rebuild"，不过Rebuild包含Clean+Build流程，配置AfterTargets="Build"也会在Rebuild时生效。

修改后重新构建，即可在输出窗口看到Build completed successfully!的消息。

内容的提问来源于stack exchange，提问作者Rod