[clang] [Clang][RFC] Introduce a trait to determine the structure binding size (PR #131515)

[via cfe-commits]

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@@ -1642,6 +1661,56 @@ void Sema::CheckCompleteDecompositionDeclaration(DecompositionDecl *DD) {
     DD->setInvalidDecl();
 }
 
+std::optional<unsigned> Sema::GetDecompositionElementCount(QualType T,
+                                                           SourceLocation Loc) {
+  const ASTContext &Ctx = getASTContext();
+  assert(!T->isDependentType());
+
+  Qualifiers Quals;
+  QualType Unqual = Context.getUnqualifiedArrayType(T, Quals);
+  Quals.removeCVRQualifiers();
+  T = Context.getQualifiedType(Unqual, Quals);
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cor3ntin wrote:

> Why do we need to do this dance

const objects of class types are decomposable

> Should the code be moved down to above the isTupleLike call?

No, for tuple-like types we already handle their constness

https://github.com/llvm/llvm-project/pull/131515