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

[Matheus Izvekov via cfe-commits]

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@@ -74,6 +74,13 @@ QualType clang::desugarForDiagnostic(ASTContext &Context, QualType QT,
       QT = AT->desugar();
       continue;
     }
+    // ... or an overflow behavior type.
+    if (const OverflowBehaviorType *OBT = dyn_cast<OverflowBehaviorType>(Ty)) {
+      if (!OBT->isSugared())
+        break;
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mizvekov wrote:

OverflowBehaviorType is never a sugar node:
```suggestion
```

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