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

[Justin Stitt via cfe-commits]

JustinStitt wrote:

> I’m a little concerned about not allowing the attribute in C++ - the existence of other options in C++ does not mean they are an option (due to various and sundry restrictions of C++ version upgrades different projects have), but also you trivially end up in cases where header code is correct/safe in C, but undefined when included in C++.
> 
> To me that seems like a significant footgun.

Yes, great point. The attribute should support C++ fairly well right now but the frontend doesn't allow it to be enabled because I am not certain how the magics of the c++ type/attribute system will interact with it. I figured a good starting point is to get the attribute working with C.

other comment in thread about avoiding issues by disabling c++ support: https://github.com/llvm/llvm-project/pull/86618#issuecomment-2050356907

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