[clang] [Clang] Diagnose require_explicit_initialization for C tentative definitions (PR #234210)

[Chen Miao via cfe-commits]

================
@@ -419,6 +419,11 @@ features cannot lower the translation-unit ABI level;
 
 ### Improvements to Clang's diagnostics
 
+- `-Wuninitialized-explicit-init` now diagnoses C tentative definitions that are
+  never completed with an initializer, such as `struct S s;` at file scope,
+  which leave fields marked `require_explicit_initialization` zero-initialized.
+  (#GH232483)
----------------
ChenMiaoi wrote:

How about this? The warning is about the lack of explicit initialization, rather than zero-initialization itself.

``` suggestion
- Fixed missing `-Wuninitialized-explicit-init` warnings for C file-scope
  tentative definitions containing fields marked `require_explicit_initialization`.
  (#GH232483)
```

https://github.com/llvm/llvm-project/pull/234210