Adding a case inside switch of SwiftUI struct causes long compilation time

Question

Wanted to play a bit with SwiftUI and Charts as some learning project. and encountered the issue with compiling time.

I have a SwiftUI struct conforming to ChartContent protocol in my code. To generate the content I use a switch statement. When I have 3 cases in a switch - everything compiles instantly. When adding the forth one is added - the same file compiles almost 90s.

Why it may be like that? Shall I structure my code differently to avoid such issues?

Longer example with code samples:

I have following definitions for some weather chart:

struct MeteogramContent: ChartContent {

    let parameters: [MeteogramParameter]

    init(_ parameters: [MeteogramParameter]) {
        self.parameters = parameters
    }

    var body: some ChartContent {
        ForEach(parameters) { parameter in
            ForEach(parameter.data) { dataPoint in
                switch parameter.style {
                case .line:
                    LineMark(
                        x: .value("Date", dataPoint.timestamp),
                        y: .value("Value", dataPoint.value)
                    ).foregroundStyle(by: .value("Param", parameter.name))
                case .dot:
                    PointMark(
                        x: .value("Date", dataPoint.timestamp),
                        y: .value("Value", dataPoint.value)
                    ).symbolSize(7)
                    .foregroundStyle(by: .value("Param", parameter.name))
                case .bar:
                    BarMark(
                        x: .value("Date", dataPoint.timestamp),
                        y: .value("Value", dataPoint.value)
                    ).foregroundStyle(by: .value("Param", parameter.name))
                }
            }
        }
    }
}

Which bases on the following model:

struct DataPoint: Identifiable {
    
    let id = UUID()
    let timestamp: Date
    
    let value: Double
}

typealias DataSerie = [DataPoint]

struct MeteogramParameter: Identifiable {

    enum ChartStyle {
        case line
        case dot
        case bar
    }

    let id = UUID()
    let name: String
    let data: DataSerie
    let color: Color
    let style: ChartStyle
}

then when I add

    enum ChartStyle {
        case line
        case dot
        case bar
        case range
    }

and extend MeteogramContent with handling for that another case as below, the compilation time is skyrocketing to 90s just for this single file.

struct MeteogramContent: ChartContent {

    let parameters: [MeteogramParameter]

    init(_ parameters: [MeteogramParameter]) {
        self.parameters = parameters
    }

    var body: some ChartContent {
        ForEach(parameters) { parameter in
            ForEach(parameter.data) { dataPoint in
                switch parameter.style {
                case .line:
                    LineMark(
                        x: .value("Date", dataPoint.timestamp),
                        y: .value("Value", dataPoint.value)
                    ).foregroundStyle(by: .value("Param", parameter.name))
                case .dot:
                    PointMark(
                        x: .value("Date", dataPoint.timestamp),
                        y: .value("Value", dataPoint.value)
                    ).symbolSize(7)
                    .foregroundStyle(by: .value("Param", parameter.name))
                case .bar:
                    BarMark(
                        x: .value("Date", dataPoint.timestamp),
                        y: .value("Value", dataPoint.value)
                    ).foregroundStyle(by: .value("Param", parameter.name))
                case .range:
                    AreaMark(x: .value("Date", dataPoint.timestamp),
                             yStart: .value("Value Min", 0),
                             yEnd: .value("Value Max", dataPoint.value)
                    )
                    .foregroundStyle(by: .value("Param", parameter.name))

                }
            }
        }
    }
}