[clang] [Clang] Fix assertion when __block is used on global variables in C mode (PR #194856)

[Aaron Ballman via cfe-commits]

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@@ -573,6 +573,7 @@ Bug Fixes to AST Handling
 - Fixed a bug where explicit nullability property attributes were not stored in AST nodes in Objective-C. (#GH179703)
 - Fixed a crash when parsing Doxygen ``@param`` commands attached to invalid declarations or non-function entities. (#GH182737)
 - Fixed the SourceLocation and SourceRange of reversed rewritten CXXOperatorCallExpr. (#GH192467)
+- Fixed a assertion when __block is used on global variables in C mode. (#GH183974)
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AaronBallman wrote:

```suggestion
- Fixed a assertion when ``__block`` is used on global variables in C mode. (#GH183974)
```

https://github.com/llvm/llvm-project/pull/194856