Xcode swift Error

Using Swift
1

Xcode 26.6(17F113)
在看Swift 6.4 测试版官方技术文档
Functions 的 Function Types as Return Types
小节的时候，按文档抄的代码，Xcode报错，但在swift repl 中执行是正常的。 ？ ： 运算符处明明正常，为啥报错。附代码截图：
错误提示信息：

Failed to produce diagnostic for expression; please submit a bug report (Contributing | Swift.org)

微信图片_20260711174230_7_5
微信图片_20260711174230_7_5848×406 46.6 KB

Failed to produce diagnostic for expression in u ? f : g, f:()->Int, g:()->Int
2

You have stumbled upon a type checker bug. :slight_smile:

3

Could you help pass this issue on to the official team?