[clang] Add Clang attribute to ensure that fields are initialized explicitly (PR #102040)

[Erich Keane via cfe-commits]

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@@ -1682,7 +1690,7 @@ class DeclContext {
 
     /// True if a valid hash is stored in ODRHash. This should shave off some
     /// extra storage and prevent CXXRecordDecl to store unused bits.
-    uint64_t ODRHash : 26;
+    uint64_t ODRHash : 25;
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erichkeane wrote:

I don't have a good idea what this is for, and the comment isn't particularly helpful.  Hopefully someone else can take a look.

https://github.com/llvm/llvm-project/pull/102040