[clang] [clang] Ensure fixed point conversions work in C++ (PR #68344)

[John McCall via cfe-commits]

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@@ -2192,6 +2194,9 @@ static bool IsStandardConversion(Sema &S, Expr* From, QualType ToType,
              From->isIntegerConstantExpr(S.getASTContext())) {
     SCS.Second = ICK_Compatible_Conversion;
     FromType = ToType;
+  } else if (ToType->isFixedPointType() || FromType->isFixedPointType()) {
+    SCS.Second = ICK_Fixed_Point_Conversion;
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rjmccall wrote:

I guess there's not really any value in breaking this down here?  Seems reasonable.

https://github.com/llvm/llvm-project/pull/68344