Corrupt `.swiftinterface`

[jpsim]

Describe the bug

When building the Swift FlatBuffers library with Xcode 14 / Swift 5.7, the verify-emitted-module-interface command fails with the following error:

error: verify-emitted-module-interface command failed with exit code 1 (use -v to see invocation)
bazel-out/ios-x86_64-min12.0-applebin_ios-ios_x86_64-fastbuild-ST-5ef840230b88/bin/external/swift_flatbuffers/swift/FlatBuffers.swiftinterface:161:3: error: missing return in accessor expected to return 'Swift.Int'
  }
  ^
bazel-out/ios-x86_64-min12.0-applebin_ios-ios_x86_64-fastbuild-ST-5ef840230b88/bin/external/swift_flatbuffers/swift/FlatBuffers.swiftinterface:1:1: error: failed to verify module interface of 'FlatBuffers' due to the errors above; the textual interface may be broken by project issues or a compiler bug
// swift-interface-format-version: 1.0
^

The full FlatBuffers.swiftinterface file is here: FlatBuffers.swiftinterface.zip

Notably lines 160-161 where it says the error is:

@_hasStorage internal var _minAlignment: Swift.Int = 0 {
}

Steps To Reproduce
Steps to reproduce the behavior:

$ git clone https://github.com/envoyproxy/envoy-mobile.git
$ cd envoy-mobile
$ git checkout jp-flatbuffers-swiftinterface-bug
$ git submodule update --init --recursive
$ ./bazelw build --config=ios //library/swift:ios_framework

Expected behavior

The .swiftinterface file produced should be valid.

Screenshots
N/A

Environment (please fill out the following information)

• OS: macOS 12.6 (21G115)
• Xcode Version/Tag/Branch: Xcode 14.0 (14A309)

Additional context
Add any other context about the problem here.

[mr-swifter]

It's still reproducible in swift 5.9, very simple program does't compile:

@usableFromInline
struct _Storage {
    var value: Int = 0
    @usableFromInline init() { }
}

@frozen
public struct TestStruct {
    var storage: _Storage
    
    public init() {
        storage = .init()
        value = 0
    }
    
    var value: Int {
        didSet {
            storage.value = value
        }
    }
}

compiling with swiftSettings:

            swiftSettings: [.unsafeFlags([
                "-enable-library-evolution",
                "-emit-module-interface",
                "-user-module-version", "1.0"
            ])]

Gives the same error as mention in description.

Making var value to be public workarounds the issue and correct swift interface is generated:

  @_hasStorage public var value: Swift.Int {
    get
    set
  }

@AnthonyLatsis , I see triage needed label hasn't been set for the issue, is it indented?