SymbolInfo of an Attribute that is part of a referenced assembly. I have both the assembly and the Syste.Runtime assembly referenced in the CSharpCompilation which the generator driver is using.<SemanticModel>.GetSymbolInfo(<AttributeSyntax>).Symbol I would expect it to return the attribute symbol for the attribute from the referenced assembly. Instead, I get null. I have a minimal reproducible example here: https://github.com/StrawbrryFlurry/CSharpCompilationAttributeReference, which shows this behavior.GetSymbolInfo call leading me to this line:attributeType is an ExtendedErrorTypeSymbol, that is able to resolve the namespace of the attribute in the referenced assembly (ReferenceLibrary.ReferencedAttribute) with the error:error CS0012: The type 'Attribute' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Runtime, Version=7.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'.System.Runtime Assembly correctly? I'd greatly appreciate any pointing in the right direction 