New solution parsing code does not handle duplicate project guids gracefully

[333fred]

Description

Instead of gracefully handling the error case when there are duplicate project guids, as VS and MSBuild have done in the past, the new solution parser throws in these scenarios.

Historical context for why Roslyn is testing this scenario: https://vstfdevdiv.corp.microsoft.com/DevDiv2/DevDiv/_workitems/edit/552981.

This is getting triggered by MSBuild switching to the solutionpersistence parser.

Repro

1. Checkout https://github.com/dotnet/roslyn/tree/6e36c969b3a4dbee0e966ee131e1754ff98b6115.
2. Run this test: https://github.com/dotnet/roslyn/blob/6e36c969b3a4dbee0e966ee131e1754ff98b6115/src/Workspaces/MSBuildTest/VisualStudioMSBuildWorkspaceTests.cs#L199-L207

Expected Behavior

Graceful handling of the duplicate project guid.

Actual Behavior

Microsoft.Build.Exceptions.InvalidProjectFileException : The project file could not be loaded. System.AggregateException: One or more errors occurred. ---> Microsoft.VisualStudio.SolutionPersistence.Model.SolutionException: Duplicate item 'c71872e2-0d54-4c4e-b6a9-8c1726b7b78c' of type 'SolutionProjectModel'.
Parameter name: value ---> Microsoft.VisualStudio.SolutionPersistence.Model.SolutionArgumentException: Duplicate item 'c71872e2-0d54-4c4e-b6a9-8c1726b7b78c' of type 'SolutionProjectModel'.
Parameter name: value
at Microsoft.VisualStudio.SolutionPersistence.Model.SolutionItemModel.set_Id(Guid value)
at Microsoft.VisualStudio.SolutionPersistence.Serializer.SlnV12.SlnFileV12Serializer.Reader.ReadProjectInfo(SolutionModel solution, StringTokenizer& tokenizer)
at Microsoft.VisualStudio.SolutionPersistence.Serializer.SlnV12.SlnFileV12Serializer.Reader.ParseAsync(ISolutionSerializer serializer, String fullPath, CancellationToken cancellationToken)
--- End of inner exception stack trace ---
at Microsoft.VisualStudio.SolutionPersistence.Serializer.SlnV12.SlnFileV12Serializer.Reader.ParseAsync(ISolutionSerializer serializer, String fullPath, CancellationToken cancellationToken)
at Microsoft.VisualStudio.SolutionPersistence.Serializer.SlnV12.SlnFileV12Serializer.<ReadModelAsync>d__14.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Microsoft.VisualStudio.SolutionPersistence.Serializer.SingleFileSerializerBase1.<Microsoft-VisualStudio-SolutionPersistence-ISolutionSerializer-OpenAsync>d__11.MoveNext()    --- End of inner exception stack trace ---    at System.Threading.Tasks.Task1.GetResultCore(Boolean waitCompletionNotification)
at Microsoft.Build.Construction.SolutionFile.ParseUsingNewParser()
---> (Inner Exception #0) Microsoft.VisualStudio.SolutionPersistence.Model.SolutionException: Duplicate item 'c71872e2-0d54-4c4e-b6a9-8c1726b7b78c' of type 'SolutionProjectModel'.
Parameter name: value ---> Microsoft.VisualStudio.SolutionPersistence.Model.SolutionArgumentException: Duplicate item 'c71872e2-0d54-4c4e-b6a9-8c1726b7b78c' of type 'SolutionProjectModel'.
Parameter name: value
at Microsoft.VisualStudio.SolutionPersistence.Model.SolutionItemModel.set_Id(Guid value)
at Microsoft.VisualStudio.SolutionPersistence.Serializer.SlnV12.SlnFileV12Serializer.Reader.ReadProjectInfo(SolutionModel solution, StringTokenizer& tokenizer)
at Microsoft.VisualStudio.SolutionPersistence.Serializer.SlnV12.SlnFileV12Serializer.Reader.ParseAsync(ISolutionSerializer serializer, String fullPath, CancellationToken cancellationToken)
--- End of inner exception stack trace ---
at Microsoft.VisualStudio.SolutionPersistence.Serializer.SlnV12.SlnFileV12Serializer.Reader.ParseAsync(ISolutionSerializer serializer, String fullPath, CancellationToken cancellationToken)
at Microsoft.VisualStudio.SolutionPersistence.Serializer.SlnV12.SlnFileV12Serializer.<ReadModelAsync>d__14.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Microsoft.VisualStudio.SolutionPersistence.Serializer.SingleFileSerializerBase`1.<Microsoft-VisualStudio-SolutionPersistence-ISolutionSerializer-OpenAsync>d__11.MoveNext()<---
T:\RoslynTests\debef9eb-3e52-4f12-bb95-c3d85526bc10\DuplicatedGuids.sln

[edvilme]

Maybe this is related to #83 but with project ids instead of solution folder ids?

[333fred]

Indeed, it looks very similar.

[richardstanton]

This produced an error, because the projects configurations can no longer be distinguished from each other. However, since old parsers would continue to load and potentially read invalid configuration data updating the model to reproduce this behavior. #101

[richardstanton]

This should be fixed by #101