[.NET 6] [Source Compat Failure] NSK app doesn't publish with .net6.0 SDK

[jiangzeng01]

Application Name: NSK
OS: Windows 10 RS5
CPU: X64
.NET Build Number: 6.0.100-preview.1.21071.10
Project Location: https://github.com/andysal/NSK

Verify Scenarios:
1). Windows 10 RS5 X64 + .NET Core SDK build 6.0.100-preview.1.21071.10: Fail
2). Windows 10 RS5 X64 + .NET Core SDK build 5.0.102: Pass

Repro steps

1. Source Code check at https://devdiv.visualstudio.com/DevDiv/_workitems/edit/1268776
2. dotnet publish Nsk.Web.Site.sln

Expected Result:
Build succeeded

Actual Result:

C:\Program Files\dotnet\sdk\6.0.100-preview.1.21071.10\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.ConflictResolution.targets(108,5): error NETSDK1148: Found multiple publish output files with the same relative path: C:\Users\valtunc\Desktop\AppSources\NSK\netcore\src\Nsk.Web.Site.Areas.Admin\libman.json, C:\Users\valtunc\Desktop\AppSources\NSK\netcore\src\Nsk.Web.Site\libman.json. [C:\Users\valtunc\Desktop\AppSources\NSK\netcore\src\Nsk.Web.Site\Nsk.Web.Site.csproj]

@dotnet-actwx-bot @dotnet/compat

[javiercn]

@vijayrkn I believe this is your team?

Otherwise, can you route it appropriately?

[vijayrkn]

@javiercn - I am not aware of any specific globs that pertains to libman.json. Adding @jodavis who owns the library manager feature to see if he has come across anything in this space.

[jodavis]

Library Manager doesn't use globbing patterns. It has a build task that could run during a publish, but that only looks at libman.json at the root of a given project.

Adding @jimmylewis in case I'm missing anything.

[jimmylewis]

If I understand correctly, there are two projects containing libman.json files, and they both publish to the root, which is causing a conflict? I'm not sure how LibMan fits in here in any special way that an arbitrary foo.json wouldn't. What's the difference in the outputted files between 5.0 and 6.0? Was there only one file output before but no conflict detection? Or were there two separate files before and now there's only one?

(LibMan's publish task would add other files to the output groups when publishing the project, but we don't do anything to include the libman.json file in publishing.)

[jiangzeng01]

@jimmylewis @jodavis Thanks for investigation! Do you have next step for this issue?

[jimmylewis]

@jiangzeng01 LibMan isn't in play here. We don't publish the libman.json file, so any conflicts over it must come from somewhere higher up in the publish process (e.g. if the project is publishing it, but that's out of our control).

[jiangzeng01]

@jimmylewis Is there any change in .NET 6 causing this failure? As we can publish this app with .NET 5 SDK, but failed with .NET 6 SDK. Something should be changed in .NET 6?

[jimmylewis]

@jiangzeng01 that would be my guess but I don't know what's changed in 6.0.

@vijayrkn do you know who we can loop in here?

[vijayrkn]

@jiangzeng01 - Can you share a sample that fails on "dotnet publish" with the above issue? That will help speed up the investigation.

[jiangzeng01]

@jiangzeng01 - Can you share a sample that fails on "dotnet publish" with the above issue? That will help speed up the investigation.

Repro steps
Source Code check at https://devdiv.visualstudio.com/DevDiv/_workitems/edit/1268776
dotnet publish Nsk.Web.Site.sln

You can check this app, it fails on publish if you use .NET 6 SDK.

[vijayrkn]

@jiangzeng01 Thanks for the repro steps.

Adding @sfoslund & @dsplaisted - Based on the binlog, this seems to be caused by this target _HandleFileConflictsForPublish added as a part of this PR- dotnet/sdk#14020

I haven't gone through the details but these seems to be flagged as dupes just based on the relative path though they are from 2 different projects.

@sfoslund - Can you please take a look?

[dsplaisted]

It is trying to copy both copies of libman.json to the publish folder for Nsk.Web.Site.csproj. We added an error for this for .NET 6. Previously, it would silently just choose one of the files to copy arbitrarily.

You can set the ErrorOnDuplicatePublishOutputFiles property to false to unblock testing. But we should figure out what the right thing to do here is. Is libman.json supposed to be published with the app at all? It may be that we need to exclude it from the default Content glob.

[jimmylewis]

libman.json is a tooling asset, not a runtime asset. I can't think of a reason why it would need to be deployed.