Wrong doc.comment on undocumented overridden declarations

[johnfairh]

Latest code; Xcode 832. This goes wrong:

protocol P {
    /// docs for P.m
    func m()
}

/// docs for S
struct S: P {
    func m() {}
}

SourceKitten reports doc.comment for S.m as "docs for S".

This happens because SourceKit produces full_as_xml for S.m from inherited P.m. So SyntaxMap.commentRange(beforeOffset:) scans back and finds the "docs for S" comment.

Would you consider accepting a PR to add some code along the lines of that removed by 114abc1 to detect this scenario?

(I do not think this is related to #269: the full_as_xml being present is enough to trigger.)

[jpsim]

As long as we don't regress in our docs detection in other scenarios, yes I'd gladly consider any PR 😄

[jpsim]

Fixed in #375.