[clang] [lldb] Serialize `#pragma redefine_extname` into precompiled headers. (PR #186755)

[via cfe-commits]

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@@ -965,9 +965,15 @@ class ASTReader
   SmallVector<serialization::SelectorID, 64> ReferencedSelectorsData;
 
   /// A snapshot of Sema's weak undeclared identifier tracking, for
-  /// generating warnings.
+  /// generating warnings. Note that this vector has 3n entries, being triplets
+  /// of the form C name, alias if any, and source location.
   SmallVector<serialization::IdentifierID, 64> WeakUndeclaredIdentifiers;
 
+  /// A snapshot of Sema's #redefine_extname'd undeclared identifier tracking,
+  /// for generating warnings. Note that this vector has 3n entries, being
+  /// triplets in the order of C name, asm name, and source location.
+  SmallVector<serialization::IdentifierID, 64> ExtnameUndeclaredIdentifiers;
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divVerent wrote:

I can do that, but the way I understand it, this wouldn't belong in the same PR (the comment update for the existing type might already be borderline, I can take that out if desired).

I was in fact thinking of creating such a struct for this patch, but decided not to do keep things consistent with each other.

Well, I guess, whatever Clang maintainers prefer.

https://github.com/llvm/llvm-project/pull/186755