msbuild - 为什么 %(Identity) 扩展为空字符串？

Question

我被告知以下内容应该创建一个文件的 ItemGroup，其中包含说明它们是否为只读的元数据:

<?xml version="1.0" encoding="utf-8"?>
<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003"
         DefaultTargets="Run"
         ToolsVersion="12.0">

<Target Name="Main">
    <ItemGroup>
        <MyFiles Include="test.proj"> <!-- also tried with *.*. Using test.proj (this file) to be sure it is a file that exists -->
            <ReadOnly Condition='1 == $([MSBuild]::BitwiseAnd(1, $([System.IO.File]::GetAttributes("%(Identity)"))))'>True</ReadOnly>
        </MyFiles>
    </ItemGroup> 

</Target>

<Target Name="Run" Outputs="%(MyFiles.Identity)" DependsOnTargets="Main">
  <Message Text="%(MyFiles.Identity) Not ReadOnly" Condition="%(MyFiles.ReadOnly) != True"/>
  <Message Text="%(MyFiles.Identity) ReadOnly" Condition="%(MyFiles.ReadOnly) == True" />
</Target>

</Project>

但是，我得到以下输出(从 Visual Studio 2013 的开发人员命令提示符运行时):

S:\>msbuild test.proj
Microsoft (R) Build Engine version 12.0.30723.0
[Microsoft .NET Framework, version 4.0.30319.34014]
Copyright (C) Microsoft Corporation. All rights reserved.

Build started 30/10/2014 21:18:46.
Project "S:\test.proj" on node 1 (default targets).
S:\test.proj(9,13): error MSB4184: The expression "[System.IO.File]::GetAttributes('')" cannot be evaluated. The path is not of a legal form.
Done Building Project "S:\test.proj" (default targets) -- FAILED.


Build FAILED.

"S:\test.proj" (default target) (1) ->
(Main target) ->
  S:\test.proj(9,13): error MSB4184: The expression "[System.IO.File]::GetAttributes('')" cannot be evaluated. The path is not of a legal form.

    0 Warning(s)
    1 Error(s)

Time Elapsed 00:00:00.01

S:\>

这应该有效吗？如果是这样，我哪里出错了？

Answer 1

从目标中创建项目组时，您似乎无法引用项目元数据。

将脚本更改为:

<?xml version="1.0" encoding="utf-8"?>
<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003"
         DefaultTargets="Run"
         ToolsVersion="12.0">

<ItemGroup>
    <MyFiles Include="test.proj" >
        <ReadOnly Condition='1 == $([MSBuild]::BitwiseAnd(1, $([System.IO.File]::GetAttributes("%(Identity)"))))'>True</ReadOnly>
    </MyFiles>
</ItemGroup> 

<Target Name="Run" Outputs="%(MyFiles.Identity)">
  <Message Text="%(MyFiles.Identity) Not ReadOnly" Condition="%(MyFiles.ReadOnly) != True"/>
  <Message Text="%(MyFiles.Identity) ReadOnly" Condition="%(MyFiles.ReadOnly) == True" />
</Target>

</Project>

将产生以下输出:

D:\temp\test>"C:\Program Files (x86)\MSBuild\12.0\Bin\msbuild.exe" test1.msbuild /t:run
Microsoft (R) Build Engine version 12.0.30723.0
[Microsoft .NET Framework, version 4.0.30319.18444]
Copyright (C) Microsoft Corporation. All rights reserved.

Build started 10/30/2014 4:31:35 PM.
Project "D:\temp\test\test1.msbuild" on node 1 (run target(s)).
Run:
  test.proj Not ReadOnly
Done Building Project "D:\temp\test\test1.msbuild" (run target(s)).


Build succeeded.
    0 Warning(s)
    0 Error(s)

Time Elapsed 00:00:00.17

D:\temp\test>

如果保证在脚本运行之前所有项目都存在，则可以将脚本更改为此。但是，我怀疑因为您是从他们没有的目标中使用它的。在这种情况下，您可能不得不求助于 CreateItem 任务。