Runtime: enum type descriptor returns enum tag for nested enum value in single case payload (release-only)

[stephencelis]

Describe the bug

Given the following nested enums:

public enum E1 {
  case c1(E2)
}

public enum E2 {
  case c1(Bool)
  case c2(Bool)
  case c3(Any)
}

Using the runtime to inspect the enum "tag" of E1.c1(.c2(true)) should result in returning 0 to match the index of its only case, c1.

And it does...in debug configurations.

In release configurations it returns 1 instead, which reflects the nested tag, E2.c2(true).

Steps To Reproduce

I'm using @Azoy's Echo for ease of access to the Swift runtime metadata. In particular I am using @ole's PR fork, which adds support for release builds.

Steps to reproduce the behavior:

1. Clone https://github.com/stephencelis/EnumRuntimeBug

2. cd EnumRuntimeBug

3. Run this code:

   https://github.com/stephencelis/EnumRuntimeBug/blob/01e5ee9ee92594930df8040da8c4b4e1eebc3c94/Sources/EnumRuntimeBug/main.swift#L1-L21

   And compare in debug/release:

   $ swift run -c debug EnumRuntimeBug
   tag 0
   $ swift run -c release EnumRuntimeBug
   tag 1
   Trace/BPT trap: 5

Expected behavior

Both debug and release should evaluate the same enum tag and print tag 0.

Screenshots
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Environment (please fill out the following information)

• OS: macOS 12
• Xcode Version/Tag/Branch: 14.1 (Swift 5.7)

[ole]

@stephencelis Looks like you have a copy/paste error in your bug description: (edit: fixed!)

[stephencelis]

@ole Ah yup! Thanks and done!

[tbkka]

CC: @drexin @aschwaighofer

[Azoy]

#61966

[drexin]

Fixed in #61966