[clang-tools-extra] [clang-tidy] Fix bugprone-misplaced-widening-cast false positive on bitfield assignments (PR #197554)

[via cfe-commits]

================
@@ -372,6 +372,12 @@ Changes in existing checks
   <clang-tidy/checks/bugprone/macro-parentheses>` check by printing the macro
   definition in the warning message if the macro is defined on command line.
 
+- Improved :doc:`bugprone-misplaced-widening-cast
+  <clang-tidy/checks/bugprone/misplaced-widening-cast>` check by fixing a false
+  positive on bitfield assignments when ``CheckImplicitCasts`` is enabled. The
+  checker now uses the actual bitfield width instead of the declared type to
----------------
EugeneZelenko wrote:

```suggestion
  positive on bitfield assignments when `CheckImplicitCasts` is enabled. The
  check now uses the actual bitfield width instead of the declared type to
```

Plus possible formatting changes. Also Wikipedia uses `bit field`.

https://github.com/llvm/llvm-project/pull/197554