[clang] [clang] Add clang::preferred_type attribute for bitfields (PR #69104)

[Vlad Serebrennikov via cfe-commits]

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@@ -3153,6 +3153,12 @@ def err_invalid_branch_protection_spec : Error<
   "invalid or misplaced branch protection specification '%0'">;
 def warn_unsupported_branch_protection_spec : Warning<
   "unsupported branch protection specification '%0'">, InGroup<BranchProtection>;
+def warn_attribute_underlying_type_mismatch : Warning<
+  "underlying type %0 of enumeration %1 doesn't match bit-field type %2">,
+  InGroup<BitFieldType>;
+def warn_attribute_bool_bitfield_width : Warning<
+  "bit-field that holds a boolean value should have width of 1 instead of %0">,
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Endilll wrote:

> The user could use an anonymous bitfield if they want to pad something out instead between bitfield elements instead?

I share this point of view, but Erich mentioned why oversized bit-fields are useful: https://github.com/llvm/llvm-project/pull/69104#issuecomment-1772828263

https://github.com/llvm/llvm-project/pull/69104