[clang] [Sema] Fixed faulty shift count warning (PR #69521)

[Shafik Yaghmour via cfe-commits]

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@@ -12143,8 +12143,7 @@ static void DiagnoseBadShiftValues(Sema& S, ExprResult &LHS, ExprResult &RHS,
     auto FXSema = S.Context.getFixedPointSemantics(LHSExprType);
     LeftSize = FXSema.getWidth() - (unsigned)FXSema.hasUnsignedPadding();
   }
-  llvm::APInt LeftBits(Right.getBitWidth(), LeftSize);
-  if (Right.uge(LeftBits)) {
+  if (Right.uge(LeftSize)) {
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shafik wrote:

I feel like `LeftSizeInBits` would be a more appropriate name but the changes looks right.

https://github.com/llvm/llvm-project/pull/69521