Failed to produce diagnostic for expression in SwiftUI code #73750
Description
Description
While writing a SwiftUI view, I got the following compiler error:
Failed to produce diagnostic for expression; please submit a bug report (https://swift.org/contributing/#reporting-bugs)
I isolated the cause to the following short snippet. I eventually figured out that the problem is on line 21. Where the example code has:
ForEach(categories, id: \.categoryName) { category in
it needs to handle the case where categories is nil. Replacing this line with the following fixes it:
ForEach(categories ?? [], id: \.categoryName) { category in
Note that if I remove the surrounding Group, I get the correct error:
Value of optional type '[CatalogCategory]?' must be unwrapped to a value of type '[CatalogCategory]'
so the Group is necessary to reproduce the bug.
Reproduction
import Foundation
import SwiftUI
struct CatalogCategory: Codable, Identifiable {
let categoryName: String
var id: String { return self.categoryName }
}
struct BasicsCatalogView: View {
@State var categories: [CatalogCategory]? = nil
var body: some View {
Group {
if self.categories == nil {
Text("Loading...")
}
else {
List {
ForEach(categories, id: \.categoryName) { category in
Text(category.categoryName.capitalized)
}
}
}
}
}
}Expected behavior
Instead of getting this message (which is raised at the surrounding var body: some View declaration), I should have received an error on the ForEach line, telling me that I was passing an optional to a method that expects a collection.
As described above, without the surrounding Group, I get the correct error on the correct line.
Environment
swift-driver version: 1.90.11.1 Apple Swift version 5.10 (swiftlang-5.10.0.13 clang-1500.3.9.4)
Target: arm64-apple-macosx14.0
Additional information
No response