[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;
+  NormalizedConstraint Constraint;
+  const Expr *Pattern;
+
+  FoldExpandedConstraint(FoldOperatorKind K, NormalizedConstraint C,
+                         const Expr *Pattern)
+      : Kind(K), Constraint(std::move(C)), Pattern(Pattern) {};
+
+  template <typename AtomicSubsumptionEvaluator>
+  bool subsumes(const FoldExpandedConstraint &Other,
+                AtomicSubsumptionEvaluator E) const;
+
+  static bool AreSubsumptionElligible(const FoldExpandedConstraint &A,
----------------
AaronBallman wrote:

typo: `Elligible` -> `Eligible`
`Are` -> `Is` for better grammar; or `IsEligibleForSubsumption`

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