[clang] [Clang] [C++26] Implement P2573R2: `= delete("should have a reason");` (PR #86526)

[via cfe-commits]

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@@ -1981,21 +1981,35 @@ class FunctionDecl : public DeclaratorDecl,
 
   };
 
-  /// Stashed information about a defaulted function definition whose body has
-  /// not yet been lazily generated.
-  class DefaultedFunctionInfo final
-      : llvm::TrailingObjects<DefaultedFunctionInfo, DeclAccessPair> {
+  /// Stashed information about a defaulted/deleted function body.
+  class DefaultedOrDeletedFunctionInfo final
+      : llvm::TrailingObjects<DefaultedOrDeletedFunctionInfo, DeclAccessPair,
+                              StringLiteral *> {
     friend TrailingObjects;
     unsigned NumLookups;
+    bool HasDeletedMessage;
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Sirraide wrote:

I don’t think it matters in this case because `sizeof(DefaultedOrDeletedFunctionInfo)` was already 16 before this, meaning this is just using one more byte of padding, from what I can tell, but I can also make it a bitfield seeing as we probably won’t ever need to store 4 billion lookups here.

https://github.com/llvm/llvm-project/pull/86526