[clang] [Clang] Diagnose fixed point arithmetic with `_BitInt` and `overflow` behavior types (PR #221134)

[Akash Manna via cfe-commits]

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@@ -1781,8 +1777,14 @@ QualType Sema::UsualArithmeticConversions(ExprResult &LHS, ExprResult &RHS,
     return handleComplexIntConversion(*this, LHS, RHS, LHSType, RHSType,
                                       ACK == ArithConvKind::CompAssign);
 
-  if (LHSType->isFixedPointType() || RHSType->isFixedPointType())
+  if (LHSType->isFixedPointType() || RHSType->isFixedPointType()) {
+    // N1169 4.1.4 only defines conversions between fixed point types and the
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akash-manna-sky wrote:

Fixed. @PiJoules 

https://github.com/llvm/llvm-project/pull/221134