A failed design-time build is not reported to the user and can cause errors during build that are confusing

[jeffkl]

Visual Studio Version

Any

Summary

A user can add a custom target to do something during their build. However, most users do not realize they need to exclude their target during design-time builds. A failing design-time build gives NuGet an incomplete nomination and so restore will succeed even though the design-time build failed. There's nothing bubbled up to the user as to what happened so generally users blame NuGet for not restoring.

Steps to Reproduce

1. Add a custom target to a project:

  <Target Name="BreakDesignTimeBuild" DependsOnTargets="TargetThatDoesNotExistExceptAfterRestoreSucceeds">
  </Target>

2. Load project in Visual Studio for the first time

Expected Behavior

Visual Studio/Project System should notify the user that the design-time build failed and possibly tell NuGet about it in the nomination details. Or perhaps nomination/restore should not take place until the design-time build targets succeed.

Actual Behavior

Projects load, restore succeeds, but build errors occur.

User Impact

Any user who adds custom targets that break design time build is affected. At least two customers have reported this issue in the last three months.

Workaround

Users who add custom targets should condition them so they don't affect design-time builds:

Condition="'$(DesignTimeBuild)' != 'true'"

[jeffkl]

Just had to help another person who was seeing strange build errors that were caused by the fact that the design time build failed so NuGet restore hadn't run. We really need to bubble this information up to the user somehow.

[jeffkl]

Another instance of this issue was reported at NuGet/Home#13267

[drewnoakes]

Sending back to triage.

[Psichorex]

Experiencing the same. We have a super repo and a sub repo was changed to use CNPM. Ever since that we are getting NU1008 that simply doesn't make sense. @jeffkl are you sure this is always a failing Target? How could I determine out of the 100 Targets in our solution which is failing?

[jeffkl]

I think using Project System Tools is the easiest way to diagnose design-time builds. It will generate an MSBuild binary log that should show which target(s) are failing.

Diagnosing design-time builds is described in https://github.com/dotnet/project-system/blob/main/docs/design-time-builds.md#getting-visual-studio-to-output-the-results-of-a-design-time-build