mutating func visit()

in Sources/SwiftDriver/IncrementalCompilation/SourceFileDependencyGraph.swift [234:290]
54 lines of code
9 McCabe index (conditional complexity)

      mutating func visit(record: BitcodeElement.Record) throws {
        guard let kind = RecordKind(rawValue: record.id) else { throw ReadError.unknownRecord }
        switch kind {
        case .metadata:
          // If we've already read metadata, this is an unexpected duplicate.
          guard majorVersion == nil, minorVersion == nil, compilerVersionString == nil else {
            throw ReadError.unexpectedMetadataRecord
          }
          guard record.fields.count == 2,
                case .blob(let compilerVersionBlob) = record.payload
          else { throw ReadError.malformedMetadataRecord }

          self.majorVersion = record.fields[0]
          self.minorVersion = record.fields[1]
          self.compilerVersionString = String(decoding: compilerVersionBlob, as: UTF8.self)
        case .sourceFileDepGraphNode:
          try finalizeNode()
          let kindCode = record.fields[0]
          guard record.fields.count == 5,
                let declAspect = DependencyKey.DeclAspect(record.fields[1]),
                record.fields[2] < identifiers.count,
                record.fields[3] < identifiers.count else {
            throw ReadError.malformedSourceFileDepGraphNodeRecord
          }
          let context = identifiers[Int(record.fields[2])]
          let identifier = identifiers[Int(record.fields[3])]
            self.definitionVsUse = .deserializing(record.fields[4])
          let designator = try DependencyKey.Designator(
            kindCode: kindCode, context: context, name: identifier,
            internedStringTable: internedStringTable)
          self.key = DependencyKey(aspect: declAspect, designator: designator)
          self.fingerprint = nil
          self.nodeSequenceNumber = nextSequenceNumber
          self.defsNodeDependUpon.removeAll(keepingCapacity: true)

          nextSequenceNumber += 1
        case .fingerprintNode:
          guard key != nil,
                record.fields.count == 0,
                case .blob(let fingerprintBlob) = record.payload
          else {
            throw ReadError.malformedFingerprintRecord
          }
          self.fingerprint = String(decoding: fingerprintBlob, as: UTF8.self)
        case .dependsOnDefinitionNode:
          guard key != nil,
                record.fields.count == 1 else { throw ReadError.malformedDependsOnDefinitionRecord }
          self.defsNodeDependUpon.append(Int(record.fields[0]))
        case .identifierNode:
          guard record.fields.count == 0,
                case .blob(let identifierBlob) = record.payload
          else {
            throw ReadError.malformedIdentifierRecord
          }
          identifiers.append(String(decoding: identifierBlob, as: UTF8.self).intern(in: internedStringTable))
        }
      }