[clang] [clang][NFC] Clean up InitializedEntity booleans. (PR #185335)

[Oliver Hunt via cfe-commits]

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@@ -136,6 +136,19 @@ class alignas(8) InitializedEntity {
     // that diagnostic text needs to be updated as well.
   };
 
+  enum class NRVOKind { Forbidden, Allowed };
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ojhunt wrote:

maybe explicitly declare the storage as `uint8_t` or even `bool` (something that would be ideal for an opaque bool type, or efficient vector....) just to ensure similar packing

https://github.com/llvm/llvm-project/pull/185335