[clang] [lldb] [Clang] Introduce OverflowBehaviorType for fine-grained overflow control (PR #148914)

[John McCall via cfe-commits]

rjmccall wrote:

Thanks. So IIUC, the rule is:
1. If the type of either operand of an arithmetic operator is `__ob_trap`,  the operator traps on overflow, and the result type is `__ob_trap`.
2. If either the operand type or the destination type of an integer conversion is `__ob_trap`, the conversion traps on overflow.
If that's right, that seems pretty reasonable. I still favor a scope-based approach, but this is a substantially improved type-based approach from how it was before.

https://github.com/llvm/llvm-project/pull/148914