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Author: cor3ntin

clang/include/clang/Sema/SemaConcept.h

@@ -262,6 +262,12 @@ template <typename AtomicSubsumptionEvaluator>
 bool FoldExpandedConstraint::subsumes(
     const FoldExpandedConstraint &Other,
     const AtomicSubsumptionEvaluator &E) const {
+
+  // [C++26] [temp.constr.order]
+  // a fold expanded constraint A subsumes another fold expanded constraint B if
+  // they are compatible for subsumption, have the same fold-operator, and the
+  // constraint of A subsumes that of B
+
   if (Kind != Other.Kind || !AreCompatibleForSubsumption(*this, Other))
     return false;
 

clang/lib/Sema/SemaConcept.cpp

@@ -1576,6 +1576,8 @@ NormalizedConstraint::fromConstraintExpr(Sema &S, NamedDecl *D, const Expr *E) {
              (FE->getOperator() == BinaryOperatorKind::BO_LAnd ||
               FE->getOperator() == BinaryOperatorKind::BO_LOr)) {
 
+    // Normalize fold expressions in C++26.
+
     FoldExpandedConstraint::FoldOperatorKind Kind =
         FE->getOperator() == BinaryOperatorKind::BO_LAnd
             ? FoldExpandedConstraint::FoldOperatorKind::And
@@ -1609,6 +1611,11 @@ NormalizedConstraint::fromConstraintExpr(Sema &S, NamedDecl *D, const Expr *E) {
 
 bool FoldExpandedConstraint::AreCompatibleForSubsumption(
     const FoldExpandedConstraint &A, const FoldExpandedConstraint &B) {
+
+  // [C++26] [temp.constr.fold]
+  // Two fold expanded constraints are compatible for subsumption
+  // if their respective constraints both contain an equivalent unexpanded pack.
+
   llvm::SmallVector<UnexpandedParameterPack> APacks, BPacks;
   Sema::collectUnexpandedParameterPacks(const_cast<Expr *>(A.Pattern), APacks);
   Sema::collectUnexpandedParameterPacks(const_cast<Expr *>(B.Pattern), BPacks);