[clang] [compiler-rt] [clang][UBSan] Add implicit conversion check for bitfields (PR #75481)

[John McCall via llvm-commits]

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@@ -324,6 +326,19 @@ class ScalarExprEmitter
   void EmitIntegerSignChangeCheck(Value *Src, QualType SrcType, Value *Dst,
                                   QualType DstType, SourceLocation Loc);
 
+  /// Emit a check that an [implicit] truncation of a bitfield does not
+  /// discard any bits. It is not UB, so we use the value after truncation.
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rjmccall wrote:

The last sentence of the comment seems out of place here (and on the next function).

https://github.com/llvm/llvm-project/pull/75481