[clang] [Clang] Consider preferred_type in bitfield warnings (#116760) (PR #116785)

[Aaron Ballman via cfe-commits]

================
@@ -6404,20 +6404,23 @@ def warn_bitfield_width_exceeds_type_width: Warning<
 def err_bitfield_too_wide : Error<
   "%select{bit-field %1|anonymous bit-field}0 is too wide (%2 bits)">;
 def warn_bitfield_too_small_for_enum : Warning<
-  "bit-field %0 is not wide enough to store all enumerators of %1">,
+  "bit-field %0 is not wide enough to store all enumerators of %select{|preferred type }1%2">,
   InGroup<BitFieldEnumConversion>, DefaultIgnore;
 def note_widen_bitfield : Note<
   "widen this field to %0 bits to store all values of %1">;
 def warn_unsigned_bitfield_assigned_signed_enum : Warning<
-  "assigning value of signed enum type %1 to unsigned bit-field %0; "
+  "assigning value of %select{|preferred }1signed enum type %2 to unsigned bit-field %0; "
   "negative enumerators of enum %1 will be converted to positive values">,
   InGroup<BitFieldEnumConversion>, DefaultIgnore;
 def warn_signed_bitfield_enum_conversion : Warning<
   "signed bit-field %0 needs an extra bit to represent the largest positive "
-  "enumerators of %1">,
+  "enumerators of %select{|preferred type }1%2">,
   InGroup<BitFieldEnumConversion>, DefaultIgnore;
 def note_change_bitfield_sign : Note<
   "consider making the bitfield type %select{unsigned|signed}0">;
+def note_bitfield_preferred_type : Note<
+  "preferred type for bitfield %0 specified here"
----------------
AaronBallman wrote:

```suggestion
  "preferred type for bit-field %0 specified here"
```
I filed https://github.com/llvm/llvm-project/issues/117711 to address the other ones.

https://github.com/llvm/llvm-project/pull/116785