[clang] [Clang] Add wraps attribute (for granular integer overflow handling) (PR #86618)

[Erich Keane via cfe-commits]

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@@ -282,6 +282,15 @@ Attribute Changes in Clang
   This allows the ``_Nullable`` and ``_Nonnull`` family of type attributes to
   apply to this class.
 
+- Introduced ``__attribute((wraps))__`` which can be added to type or variable
+  declarations. Using an attributed type or variable in an arithmetic
+  expression will define the overflow behavior for that expression as having
+  two's complement wrap-around. These expressions cannot trigger integer
+  overflow warnings or sanitizer warnings. They also cannot be optimized away
+  by some eager UB optimizations.
+
+  This attribute is ignored in C++.
----------------
erichkeane wrote:

```suggestion
  This attribute is only valid for C, as there are built-in language alternatives for other languages.
```

https://github.com/llvm/llvm-project/pull/86618