CodeTaskFactory error on missing attributes does not contain element name

[mhutch]

When using CodeTaskFactory, if a Reference element is missing the Include attribute, or a Using element is missing the Namespace attribute, an error is printed about an empty attribute value.

This error isn't great for a few reasons

1. It doesn't say which element the attribute is on
2. It says "The "Include" attribute has been set but is empty" even when it's missing
3. It's emitted at the point the task is used, not declared, so the message about the Include attribute is easily confused for referring to the Items passed to the task

[AndyGerlicher]

Team Triage:
This seems reasonable, marking up for grabs. Could you please include a repro with expected/actual error and a sample project file? Thanks!

[mhutch]

Sample:

<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003" DefaultTarget="Build">
  <UsingTask
    TaskName="MDDownloadFiles"
    TaskFactory="CodeTaskFactory"
    AssemblyFile="$(MSBuildToolsPath)\Microsoft.Build.Tasks.Core.dll" >
    <ParameterGroup>
      <Downloads ParameterType="Microsoft.Build.Framework.ITaskItem[]" Required="true" />
    </ParameterGroup>
    <Task>
      <Reference Assembly="System.IO.Compression" />
      <Using Import="System.IO" />
      <Code Language="cs" Source="$(MSBuildThisFileDirectory)/MDDownloadFiles.cs" />
    </Task>
  </UsingTask>
  <Target Name="Build">
    <MDDownloadFiles Downloads="@(MDDownload)" />
  </Target>
</Project>

Actual result:

test.csproj(16,5): error MSB3752: The "Include" attribute has been set but is empty. If the "Include" attribute is set it must not be empty.        

Expected result (note location is also different):

test.csproj(10,5): error MSB3752: The required "Include" attribute on the "Reference" element is missing or empty.

Note that if you delete the Reference element, you see another, similar error:

Actual result:

test.csproj(16,5): error MSB3752: The "Namespace" attribute has been set but is empty. If the "Namespace" attribute is set it must not be empty.        

Expected result (note location is also different):

test.csproj(10,5): error MSB3752: The required "Namespace" attribute on the "Using" element is missing or empty.

[jeffkl]

I'm working on a new CodeTaskFactory which is based on Roslyn and is cross platform. I think I've addressed this issue with more validation.

https://github.com/jeffkl/roslyn/blob/inlinetask/src/Compilers/Core/MSBuildTask/CodeTaskFactory.cs

[mhutch]

Nice :)

Though FWIW, my repro was already using the Roslyn compiler and running on a Mac.

[jeffkl]

The CodeTaskFactory that ships with Microsoft.Build.Tasks.Core.dll uses the .NET CodeDom library which does not work on .NET Core. We've had to disable this CodeTaskFactory on .NET Core and instead I'm working on this other CodeTaskFactory that will ship with the Roslyn MSBuild task library which will use Roslyn to compile an in-memory assembly. Hopefully that makes sense.

[rainersigwald]

The old CodeTaskFactory is disabled on .NET Core.

The Mono implementation of CodeDOM can use Roslyn (awesome!) and CodeTaskFactory works in Mono, modulo this issue.

We should figure out a strategy for inline tasks on Mono. It should probably just go with the desktop/full framework approach, but we should be explicit about it.

[mhutch]

And please note that everyone using Visual Studio for Mac is using msbuild on Mono, not on .NET Core, and that is extremely unlikely to change.

[octaviobffernandes]

any update?