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

[Eli Friedman via cfe-commits]

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@@ -147,6 +147,7 @@ struct ImplicitConversionData {
   const TypeDescriptor &FromType;
   const TypeDescriptor &ToType;
   /* ImplicitConversionCheckKind */ unsigned char Kind;
+  unsigned int BitfieldBits;
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efriedma-quic wrote:

Do we have an ABI stability policy for UBsan?  Is the change allowed under it?

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