Generating compilable name from INamedTypeSymbol

[bradwilson]

I am writing an incremental generator, and given an INamedTypeSymbol, I need to be able to create a compilable reference to the type. By way of example, I might need to use the type name in a new statement or as a generic type in the code I'm generating.

I had been under the (perhaps mistaken) impression that calling .ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat) was the correct way, but I've noticed that this drops nullable annotations; if, for example, my symbol points to object?[], the result of the call to .ToDisplayString is object[].

Looking at the definition of FullyQualifiedFormat it seems to be one of the few default display formats that does not include SymbolDisplayMiscellaneousOptions.IncludeNullableReferenceTypeModifier. The names of the other symbol formats imply that they're more intended to be used for user-facing purposes (like when reporting diagnostics).

So I guess my question is this:

Is ToDisplayString the canonical way to get a compilable reference to a symbol?

• If so, does one of the default SymbolDisplayFormat values represent the intended future-proof way to get a compilable name for a type reference? Or is there a suggested set to values to provide to SymbolDisplayFormat that would achieve this?
• If ToDisplayString is not the canonical way, what is?

[CyrusNajmabadi]

Is ToDisplayString the canonical way to get a compilable reference to a symbol?

Yes. But only for type symbols. Any other symbol is something you will have to take care of yourself.

If so, does one of the default SymbolDisplayFormat values represent the intended future-proof way to get a compilable name for a type reference?

No.

[bradwilson]

No.

Is there a combination of flags the team would generally recommend in this scenario? Right now I'm doing FullyQualifiedFormat + SymbolDisplayMiscellaneousOptions.IncludeNullableReferenceTypeModifier and it seems to be what I've needed so far, but I'm curious if there are edge cases I might be missing.

Note that I'm only supporting C#.

[CyrusNajmabadi]

Your combination of flags seems reasonable.