Blazor AOT compilation fails at ComputeBlazorPublishAssets.GroupExistingStaticWebAssets

[johngsandiford]

This follows on from issue #35633 which is closed but unfortunately not fixed for us in 6 RC2.

Please see output below. We have spent a lot of time trying to repro on a simple project, but without knowing what the key is, in a large project such as ours it has not yet been possible.

Is it possible to report the key causing the problem?

Thanks, John

C:\Program Files\dotnet\sdk\6.0.100-rc.2.21505.57\Sdks\Microsoft.NET.Sdk.BlazorWebAssembly\targets\Microsoft.NET.Sdk.BlazorWebAssembly.6_0.targets(404,5): Error : System.ArgumentException: An item with the same key has already been added.
at System.ThrowHelper.ThrowArgumentException(ExceptionResource resource)
at System.Collections.Generic.Dictionary2.Insert(TKey key, TValue value, Boolean add) at Microsoft.NET.Sdk.BlazorWebAssembly.ComputeBlazorPublishAssets.GroupExistingStaticWebAssets(Dictionary2 assemblyAssets, Dictionary2 nativeAssets, Dictionary2 satelliteAssemblyAssets, Dictionary2 symbolAssets, Dictionary2 compressedRepresentations)
at Microsoft.NET.Sdk.BlazorWebAssembly.ComputeBlazorPublishAssets.Execute()

[javiercn]

@johngsandiford thanks for contacting us.

We added logic to detect duplicates, but apparently we did so in a different method.

You can capture a binary log with dotnet publish /bl and use MSBuild structured log viewer to look at the ComputeBlazorPublishAssets task. Within there, if you expand the parameters, it'll show all the ExistingAssets and you can get a better idea of what's happening. (You'll see the duplicated asset).

If you can create a minimal repro, that would help us investigate what's going on.

[johngsandiford]

Thanks @javiercn . I have now made some progress, and was able to workaround what looks to be a bug. I don't think that it is AOT related.

I haven't been able to create a simple repro, despite trying, but the following might help...

Detail

1. The partial output of the binlog listed at the end of this post shows 4 duplicates of the following:
   ...\obj\Debug\net6.0\build-gz\SveEUeme.gz

2. Inside each of the 4 duplicate .gz entries refers to a different assembly.

3. One of the referenced assemblies BayesServer.UI.Shared.dll is a class library referenced directly from out WASM Blazor project.

4. The other 3 assemblies are referenced from BayesServer.UI.Shared.dll but not the WASM Blazor project.

5. The only difference between these 3 assemblies and all our other assemblies, is that they are not referenced by our WASM Blazor project directly.

6. If we do add references to the 3 assembles from the WASM Blazor project as well, it works.

Binlog

C:\Users\<retracted>\BayesServer.Web.UI.Wasm.Preview\obj\Debug\net6.0\build-gz\SveEUeme.gz
    RelativePath = _framework/BayesServer.UI.Shared.dll.gz
    BasePath = /
    AssetMode = All
    AssetKind = Build
    SourceId = BayesServer.Web.UI.Wasm.Preview
    CopyToOutputDirectory = PreserveNewest
    RelatedAsset = C:\Users\<retracted>\BayesServer.Web.UI.Wasm.Preview\bin\Debug\net6.0\wwwroot\_framework\BayesServer.UI.Shared.dll
    ContentRoot = C:\Users\<retracted>\BayesServer.Web.UI.Wasm.Preview\bin\Debug\net6.0\wwwroot\
    SourceType = Computed
    AssetRole = Alternative
    AssetTraitValue = gzip
    AssetTraitName = Content-Encoding
    OriginalItemSpec = C:\Users\<retracted>\BayesServer.Web.UI.Wasm.Preview\bin\Debug\net6.0\wwwroot\_framework\BayesServer.UI.Shared.dll
    CopyToPublishDirectory = Never


C:\Users\<retracted>\BayesServer.Web.UI.Wasm.Preview\obj\Debug\net6.0\build-gz\SveEUeme.gz
    RelativePath = _framework/BayesServer.Causal.dll.gz
    BasePath = /
    AssetMode = All
    AssetKind = Build
    SourceId = BayesServer.Web.UI.Wasm.Preview
    CopyToOutputDirectory = PreserveNewest
    RelatedAsset = C:\Users\<retracted>\BayesServer.Web.UI.Wasm.Preview\bin\Debug\net6.0\wwwroot\_framework\BayesServer.Causal.dll
    ContentRoot = C:\Users\<retracted>\BayesServer.Web.UI.Wasm.Preview\bin\Debug\net6.0\wwwroot\
    SourceType = Computed
    AssetRole = Alternative
    AssetTraitValue = gzip
    AssetTraitName = Content-Encoding
    OriginalItemSpec = C:\Users\<retracted>\BayesServer.Web.UI.Wasm.Preview\bin\Debug\net6.0\wwwroot\_framework\BayesServer.Causal.dll
    CopyToPublishDirectory = Never


C:\Users\<retracted>\BayesServer.Web.UI.Wasm.Preview\obj\Debug\net6.0\build-gz\SveEUeme.gz
    RelativePath = _framework/BayesServer.Optimization.dll.gz
    BasePath = /
    AssetMode = All
    AssetKind = Build
    SourceId = BayesServer.Web.UI.Wasm.Preview
    CopyToOutputDirectory = PreserveNewest
    RelatedAsset = C:\Users\<retracted>\BayesServer.Web.UI.Wasm.Preview\bin\Debug\net6.0\wwwroot\_framework\BayesServer.Optimization.dll
    ContentRoot = C:\Users\<retracted>\BayesServer.Web.UI.Wasm.Preview\bin\Debug\net6.0\wwwroot\
    SourceType = Computed
    AssetRole = Alternative
    AssetTraitValue = gzip
    AssetTraitName = Content-Encoding
    OriginalItemSpec = C:\Users\<retracted>\BayesServer.Web.UI.Wasm.Preview\bin\Debug\net6.0\wwwroot\_framework\BayesServer.Optimization.dll
    CopyToPublishDirectory = Never

C:\Users\<retracted>\BayesServer.Web.UI.Wasm.Preview\obj\Debug\net6.0\build-gz\SveEUeme.gz
    RelativePath = _framework/BayesServer.Editing.dll.gz
    BasePath = /
    AssetMode = All
    AssetKind = Build
    SourceId = BayesServer.Web.UI.Wasm.Preview
    CopyToOutputDirectory = PreserveNewest
    RelatedAsset = C:\Users\<retracted>\BayesServer.Web.UI.Wasm.Preview\bin\Debug\net6.0\wwwroot\_framework\BayesServer.Editing.dll
    ContentRoot = C:\Users\<retracted>\BayesServer.Web.UI.Wasm.Preview\bin\Debug\net6.0\wwwroot\
    SourceType = Computed
    AssetRole = Alternative
    AssetTraitValue = gzip
    AssetTraitName = Content-Encoding
    OriginalItemSpec = C:\Users\<retracted>\BayesServer.Web.UI.Wasm.Preview\bin\Debug\net6.0\wwwroot\_framework\BayesServer.Editing.dll
    CopyToPublishDirectory = Never

[javiercn]

@johngsandiford thanks.

This helps to better understand the issue. It seems that for some reason, when we compress the files some of them seem to be getting the same Identity.

Could you check on the binlog when you identify that the assets get duplicated?

Probably check if there are duplicates on the inputs to this task GZipCompress or right afterwards in the outputs of the task (_BlazorBuildGZipCompressedFile) or in (_BlazorGzipStaticWebAsset)

Otherwise, could you check if the duplicates are present in obj\Debug\net6.0\build.staticwebassets.json?

[johngsandiford]

The GZipCompress task has duplicates of the following

C:\Users<redacted>\bin\Debug\netstandard2.0\BayesServer.UI.Shared.dll

The ComputeBlazorFilesToCompress task before has no duplicates.

If you need the binlog, happy to share privately.

Regards, John

[javiercn]

@johngsandiford Thanks for the additional details.

Can you share a "sanitized" version of the inputs to the task? That will hep us debug the task itself and understand what's going on. There might also be log messages in the binlog (if you look at the task node it should contain the messages in grey) that might help us identify what's going on.

Are the assemblies in your app being referenced via ProjectReference?