[clang] [Clang][C++26] Implement "Ordering of constraints involving fold expressions (PR #98160)

[Aaron Ballman via cfe-commits]

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@@ -143,13 +148,116 @@ struct NormalizedConstraint {
     return Constraint.get<AtomicConstraint *>();
   }
 
+  FoldExpandedConstraint *getFoldExpandedConstraint() const {
+    assert(isFoldExpanded() &&
+           "getFoldExpandedConstraint called on non-fold-expanded constraint.");
+    return Constraint.get<FoldExpandedConstraint *>();
+  }
+
 private:
   static std::optional<NormalizedConstraint>
   fromConstraintExprs(Sema &S, NamedDecl *D, ArrayRef<const Expr *> E);
   static std::optional<NormalizedConstraint>
   fromConstraintExpr(Sema &S, NamedDecl *D, const Expr *E);
 };
 
+struct FoldExpandedConstraint {
+  enum class FoldOperatorKind { FoAnd, FoOr } Kind;
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AaronBallman wrote:

Do we need the `Fo` prefix since this is a scoped enumeration anyway?

https://github.com/llvm/llvm-project/pull/98160