Template Code 无法使用 this.Host 报错

问题显示：

Error 6
Compiling transformation: 'Microsoft.VisualStudio.TextTemplatingBED07DAE3B6FD53FA947017E5A5F7A123173F8AEEBD8059AD94FFEA4200EC409BE022035F5E3463EFD6E2867E0DEFBDC09BAEEE8B986A775611AFBBB7D110480.GeneratedTextTransformation' does not contain a definition for 'Host'
and no extension method 'Host' accepting a first argument of type 'Microsoft.VisualStudio.TextTemplatingBED07DAE3B6FD53FA947017E5A5F7A123173F8AEEBD8059AD94FFEA4200EC409BE022035F5E3463EFD6E2867E0DEFBDC09BAEEE8B986A775611AFBBB7D110480.GeneratedTextTransformation'
could be found (are you missing a using directive or an assembly reference?)
e:\Projects\XYX\XYX.Server\MarketDataModuleClientInterface\api.helper.tt
24 50
IMarketDataModuleClientlLibrary

其实问题很简单：

<#@ template hostspecific="true" language="C#" #>
<#@ output extension=".txt" #>
<#@ import namespace="System.CodeDom.Compiler" #>
<#
  string message = "test message";
  this.Host.LogErrors(new CompilerErrorCollection()
    { new CompilerError(
       this.Host.TemplateFile, // Identify the source of the error.
       0, 0, "0",   // Line, column, error ID.
       message) }); // Message displayed in error window.
#>

注意第一行： hostspecific="true"

如果是 false就会出现最前面的那个错误