[clang] [Clang] Implement P0963R3 "Structured binding declaration as a condition" (PR #130228)

[Younan Zhang via cfe-commits]

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@@ -4224,15 +4224,18 @@ class DecompositionDecl final
     : public VarDecl,
       private llvm::TrailingObjects<DecompositionDecl, BindingDecl *> {
   /// The number of BindingDecl*s following this object.
-  unsigned NumBindings;
+  unsigned NumBindings : 31;
+
+  LLVM_PREFERRED_TYPE(bool)
+  unsigned IsDecisionVariable : 1;
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zyn0217 wrote:

I tried that approach in the first place, but it turns out to bring significant churn in the evaluator's current structure. Adding a lot of bool flags on the caller side and since we have recursive calls, makes maintaining these flags become an additional burden. TBH I don't like it because I really feel it makes the code messy

https://github.com/llvm/llvm-project/pull/130228