[clang] [Clang] Fix false-positive fallthrough warning (#230802) (PR #234848)

[Chen Miao via cfe-commits]

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@@ -458,9 +408,7 @@ documentation](CIR/index.md) for more information regarding ClangIR's status and
 
 ### Improvements to Clang's diagnostics
 
-- Fixed missing `-Wuninitialized-explicit-init` warnings for C file-scope
-  tentative definitions of structure types which contain a field marked with
-  the `require_explicit_initialization` attribute. (#GH232483)
+- Clang no longer emits a false-positive `-Wimplicit-fallthrough` warning when consecutive switch labels share a body and are annotated with attributes like `[[unlikely]]`. (#GH230802)
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ChenMiaoi wrote:

Although the 80-column limit doesn’t apply to documentation, I think this line is a bit too long. Perhaps wrapping it at around 80 characters would be better?

For other requirements, you can refer to the [LLVM Coding Standards](https://llvm.org/docs/CodingStandards.html#source-code-width).

https://github.com/llvm/llvm-project/pull/234848