ToolsVersion should be ignored by MSBuild task

[jeffkl]

MSBuild ignores ToolsVersion in most places but the MSBuild task is still trying to honor it

Steps to reproduce

If you specify an invalid ToolsVersion to an MSBuild task invocation, the build will fail:

Project file

<Project>
  <ItemGroup>
    <MyProjects Include="$(MSBuildProjectFullPath)"
                ToolsVersion="BadToolsVersion" />
  </ItemGroup>

  <Target Name="Build">
    <MSBuild Projects="@(MyProjects)" />
  </Target>
</Project>

Command line

msbuild /bl

Expected behavior

ToolsVersion to not be respected and ignored like ToolsVersion is ignored everywhere else.

Actual behavior

Build error:

error MSB4132: The tools version "BadToolsVersion" is unrecognized. Available tools versions are "Current", "2.0", "3.5", "4.0".

Environment data

msbuild /version output:

Microsoft (R) Build Engine version 16.1.59-preview+gd8f1537cf1 for .NET Framework
Copyright (C) Microsoft Corporation. All rights reserved.

16.1.59.61912

[mwpowellhtx]

So... Looking for workarounds, resolutions. Besides potentially need to install and/or re-install SDKs, runtimes, etc. Haven't gotten quite that far in my troubleshooting. Short of that, crude answer is for us to visit each of our .csproj project files and add the ToolsVersion attribute in the appropriate version? I assume that's 15.0 for VS2017? Is there a more elegant way to do that in swath? i.e. through Directory.Build.props, for instance, by convention, as contrasted with by specification?

[livarcocc]

@mwpowellhtx what are the errors you are getting? This shouldn't really matter to runtimes and things like that.

[mwpowellhtx]

@livarcocc We are currently blocked trying to load projects in our test environment for Roslyn build. Started here, but not positive this is a build issue as much as anything. So far in our investigation we have identified a ton of folks with similar issues, but no clear cut solution.