SymbolGraphGen: Provide support for including underscored or unavailable symbols

[QuietMisdreavus]

Per the discussion in #59957, it's important for users of the symbol graph to be able to find all the public symbols, even those that are implicitly private by having an underscored name (e.g. _SomeType) or by being marked as "unconditionally unavailable" (i.e. @available(*, unavailable)). Providing a flag to swift-frontend and swift-symbolgraph-extract to include these symbols will allow tools to perform this filtering on their own, rather than relying on SymbolGraphGen's assumptions that were originally written for Swift-DocC.

[AnthonyMDev]

+1. I'd really love to see this option make its way into the compiler. This is a pretty big limitation for DocC in our use case. swiftlang/swift-docc#342 (comment)

[tayloraswift]

has there been any movement on this?

[tayloraswift]

actually i’ve discovered SymbolGraphGen automatically lowers their access visibility by one level (e.g. public → internal), but preserves the original ACL metadata, so it is sufficient for my use case to just lower the minimum ACL. closing this issue for now…

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oops, don’t have the ability to close this issue. but feel free to close it!