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

[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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cor3ntin wrote:

I am questioning if we really need that.
We know from context if it is or not (ie it's not really a property of the declaration)

- In a _condition_ a DecompositionDecl is always a decision variable
- Outside, it never is.

Maybe
`Compiler<Emitter>::visitDeclStmt`, `CodeGenFunction::EmitDecl`, `EvaluateDecl` can be modified
to take a bool that indicates whether we are in the context of a _condition_.

Is that an approach you considered?





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