Wix Toolset v4(5.0.0)：含引用动作时覆盖StartServices标准动作失败

我尝试自定义StartServices标准动作，单独编译安装包可以成功执行，但添加ScheduleReboot引用动作后，编译失败并抛出WIX7009错误。项目是从WiX v3迁移到v4的，原动作序列在v3中可正常运行，示例代码如下：

<Wix xmlns="http://wixtoolset.org/schemas/v4/wxs">

  <Package Name="WixTest"
           Version="1.0.0"
           Manufacturer="Any Company"
           UpgradeCode="{75393798-99D0-4342-BA82-D7CDE7DAA27F}">

    <Feature Id="Feature" ConfigurableDirectory="INSTALLDIR" />

    <!-- If the ScheduleReboot action is commented out the compile will succeed 
           if uncommented, the compile will fail with:
           
           Error    WIX7009 The action 'StartServices' conflicts with a virtual symbol with the same id. To override the virtual symbol (e.g., to reschedule a custom action), use the 'override' access modifier: 'override StartServices'. If you didn't intend to override a virtual symbol, use a different id to avoid the conflict.   wixtest D:\save\wixtest\Product.wxs 21      
      -->
    <InstallExecuteSequence>
      <!-- <ScheduleReboot Before="StartServices" Condition="RESTART_REQUIRED=1" /> -->
      <StartServices Condition="RESTART_SERVICES=1" />
    </InstallExecuteSequence>

    <StandardDirectory Id="ProgramFilesFolder" >
      <Directory Id="INSTALLDIR" Name="installHere"/>
    </StandardDirectory>
  </Package>
</Wix>

问题原因 #

WiX v4的动作序列机制和v3存在差异：当你在序列中引用ScheduleReboot这类标准动作时，WiX会自动引入该动作所属的默认标准序列集，其中已经包含了默认的StartServices动作。此时你自定义的StartServices因未明确声明是覆盖默认动作，就会和默认序列里的同名动作产生冲突，触发WIX7009错误。而WiX v3不会自动引入这些依赖的标准动作序列，因此不会出现该问题。

解决方法 #

在自定义的StartServices元素前加上override关键字，明确告知WiX你要覆盖默认的虚拟动作，修改后的InstallExecuteSequence代码如下：

<InstallExecuteSequence>
  <ScheduleReboot Before="StartServices" Condition="RESTART_REQUIRED=1" />
  <override StartServices Condition="RESTART_SERVICES=1" />
</InstallExecuteSequence>

这样编译时WiX会识别你是要替换默认的StartServices动作，即可避免冲突。

内容的提问来源于stack exchange，提问作者Bill Packard