Item Functions are not parsed correctly in conditions

[rainersigwald]

This came up on an internal mailing list. A user was trying to emit a message if an item didn't contain a certain element, and I recommended using the Item Function AnyHaveMetadataValue. But that produces an error:

<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <ItemGroup>
    <MainEmbeddedFiles Include="foo.baml" />
    <MainEmbeddedFiles Include="UserControl1.baml" />
  </ItemGroup>

  <Target Name="b">
    <Error Text="Missing expected BAML file!!!"
           Condition="!@(MainEmbeddedFiles->AnyHaveMetadataValue('Filename', 'UserControl1'))" />
  </Target>
</Project>

d:\play>msbuild test.proj /v:q /nologo
d:\play\test.proj(9,12): error MSB4092: An unexpected token ")" was found at character position 71 in condition "!@(MainEmbeddedFiles->AnyHaveMetadataValue('Filename', 'UserControl1'))".

This can be worked around by creating a property:

  <Target Name="b">
    <PropertyGroup>
      <HasFile>@(MainEmbeddedFiles->AnyHaveMetadataValue('Filename', 'UserControl1'))</HasFile>
    </PropertyGroup>
    <Error Text="Missing expected BAML file!!! @(MainEmbeddedFiles->AnyHaveMetadataValue('Filename', 'UserControl1'))"
           Condition="!$(HasFile)" />
  </Target>

I see no reason that we should behave differently in a Condition.

[nikson]

Is it still open for grab?

[rainersigwald]

@nikson Yes, this is still up for grabs. However, it's in a part of the code that hasn't seen changes in a while, so we'd like to be cautious. If you'd like to take a look, can you post a quick summary of the changes you think you'll make before going all the way through the fix? (Of course, if it's easier to just send a PR with a proposed fix, that's fine, but I'd like to potentially save some of your time by considering an approach first.)