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

[Matheus Izvekov via cfe-commits]

================
@@ -14308,6 +14455,12 @@ static QualType getCommonNonSugarTypeNode(const ASTContext &Ctx, const Type *X,
         getCommonTypeKeyword(NX, NY, /*IsSame=*/true),
         getCommonQualifier(Ctx, NX, NY, /*IsSame=*/true), NX->getIdentifier());
   }
+  case Type::OverflowBehavior: {
+    // FIXME: Should we consider both types?
+    const auto *NX = cast<OverflowBehaviorType>(X);
+    return Ctx.getOverflowBehaviorType(NX->getBehaviorKind(),
+                                       NX->getUnderlyingType());
----------------
mizvekov wrote:

Yes :)

```suggestion
    const auto *NX = cast<OverflowBehaviorType>(X), *NY = cast<OverflowBehaviorType>(Y);
    assert(NX->getBehaviorKind() = NY->getBehaviorKind());
    return Ctx.getOverflowBehaviorType(NX->getBehaviorKind(), ::getCommonUnderlyingType(NX, NY));
```

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