Error "Failed to produce diagnostic" instead of an actionable description of a coding error.

[fritza-ws]

Describe the bug
Compiling the attached project yields a "Failed to produce diagnostic" instead of an informative (if any) error message.

Steps To Reproduce

1. Unzip the attached project
2. Open the project
3. Command a build (Product → Build ⌘B)

Expected behavior
The build completes, either accepting the presented code or issuing an error or warning as appropriate.

Actual behavior
An error at PlanetGroupListView.swift:17, with only a message saying swiftc "failed to produce diagnostic" and soliciting this report.

Screenshots
n/a

Environment (please fill out the following information)
macOS 13.0.1 (22A400)
Xcode version 14.1 (14B47b)

31% memory pressure
305 GB available storage

Force-Quit dialog shows 13 applications open.

Additional context
After quitting Xcode and the Simulator app, and relaunching Xcode, the issue persists.

A file containing logs for the compilation stages are attached. SwiftCompile(first round) was flagged as an error but didn't show any diagnostic.

Project directory
LastChance.zip

Compile phases - log
Swift Compile Diagnostic - fritza - 16-Nov-2022.txt

[fritza-ws]

1. Quit Xcode
2. Delete the project Derived Data (~/Library/Developer/Xcode/DerivedData)
3. Relaunch Xcode

Had no effect.

[xedin]

Just to help you out here - the problem is with \.children it's type is KeyPath<PlanetClass, [String]?> but the parameter expects [Planets]?. There is a reference to this at https://developer.apple.com/documentation/swiftui/list - "Creating hierarchical lists"

[AnthonyLatsis]

@fritza-ws FYI This is a fallback compiler error for when we know something is wrong but aren't able to produce a meaningful diagnostic, so this is a Swift compiler bug, not an Xcode one.