An `init` declaration inside computed property of function type crashes compiler

Description An init declaration inside a computed property crashes the compiler when said property has a function type. I had no idea these declarations were valid Swift but they're emitted by the @ObservationTracked macro but you can reproduce this error without using it and without importing any frameworks.

Steps to reproduce

Shortest repro (using Observation + macros in Xcode 15b3):

import Observation

@Observable
class ThisCrashes1 {
  var content: (() -> Bool)? = nil
}

Minimal repro without Observation or macros:

class ThisCrashes2 {
  var content: (() -> Bool)? {
    // This init declaration is the cause of the crash
    // Only for function types
    // For example `Bool?` does not crash
    // While `(() -> Bool)?` does
    // If you comment it out the crash no longer happens
    init(initialValue) initializes (_content) {
      _content = initialValue
    }

    get {
      return _content
    }

    set {
      _content = newValue
    }
  }

  private var _content: (() -> Bool)? = nil
}

I also have a repro that involves Swift UI. I assume the underlying cause is the same however the stack trace output is different so I figured it might also be useful:

import SwiftUI
import Observation

@Observable
class ThisCrashes1 {
  var content: (() -> any View)? = nil
}

Expected behavior The compiler doesn't crash. Maybe there's a build error (not sure if the above is supposed to be valid or not). But it definitely shouldn't crash.

Environment

swift-driver version: 1.85 Apple Swift version 5.9 (swiftlang-5.9.0.120.7 clang-1500.0.34.3) Target: arm64-apple-macosx13.0
Xcode 15.0 Build version 15A5195k
Deployment target: iOS 17.0, macOS 13.0, etc…

Additional context

Here's the stack traces for all three repros above: https://gist.github.com/thecrypticace/756927dde4d6722c1359a53bc468a972

swiftlang / swift

An `init` declaration inside computed property of function type crashes compiler #67477