SyntaxTree serialization fails trying to write VB date time literal

[mattwar]

This code:

Public Class C
Private _x As DateTime = #10/5/2015#
End Class

Causes this exception when the tree gets serialized:

System.InvalidOperationException: Cannot serialize type 'System.DateTime'.
at Roslyn.Utilities.StreamObjectWriter.WriteObject(Object instance)
at Roslyn.Utilities.StreamObjectWriter.WriteVariant(Variant value)
at Roslyn.Utilities.StreamObjectWriter.Emit()
at Roslyn.Utilities.StreamObjectWriter.WriteValue(Object value)
at Microsoft.CodeAnalysis.SyntaxNode.SerializeTo(Stream stream, CancellationToken cancellationToken)
at Microsoft.CodeAnalysis.Host.AbstractSyntaxTreeFactoryService.RecoverableSyntaxRoot`1.d__6.MoveNext()

[Pilchie]

Can we get more details about when this happens? @asecchia?

[mattwar]

How can it be more clear than the title of the issue?

[Pilchie]

How does a user experience this? Does this crash VS whenever there is a VB file with a date constant? Should this be in RC instead of RC2?

[mattwar]

The bug is caused by my recent change to the serializer that is in master and not in RC.

[Pilchie]

Ah, great! Thanks!

[asecchia]

I opened roslyn.sln and VS crashed (failfast)

[mattwar]

@Pilchie there is a nice PR here for you to green light #14944

[dpoeschl]

Reopening because this change was reverted as part of #15068

[dpoeschl]

FYI @mattwar

[mattwar]

This only failed because of the serialization changes you also rolled back.