[clang] [Clang][RFC] Introduce a trait to determine the structure binding size (PR #131515)

[Aaron Ballman via cfe-commits]

================
@@ -5066,6 +5066,10 @@ static bool CheckUnaryTypeTraitTypeCompleteness(Sema &S, TypeTrait UTT,
   case UTT_IsInterfaceClass:
     return true;
 
+  // We diagnose incomplete class types later
----------------
AaronBallman wrote:

```suggestion
  // We diagnose incomplete class types later.
```

https://github.com/llvm/llvm-project/pull/131515