Refactor canonical type ordering

include/swift/AST/GenericSignature.h

@@ -472,6 +472,11 @@ inline bool CanGenericSignature::isActuallyCanonicalOrNull() const {
          getPointer()->isCanonical();
 }
 
+int compareAssociatedTypes(AssociatedTypeDecl *assocType1,
+                           AssociatedTypeDecl *assocType2);
+
+int compareDependentTypes(Type type1, Type type2);
+
 } // end namespace swift
 
 namespace llvm {

include/swift/AST/GenericSignatureBuilder.h

@@ -1677,9 +1677,6 @@ inline bool isErrorResult(GenericSignatureBuilder::ConstraintResult result) {
   llvm_unreachable("unhandled result");
 }
 
-/// Canonical ordering for dependent types.
-int compareDependentTypes(Type type1, Type type2);
-
 template<typename T>
 Type GenericSignatureBuilder::Constraint<T>::getSubjectDependentType(
                       TypeArrayView<GenericTypeParamType> genericParams) const {

include/swift/AST/Requirement.h

@@ -92,6 +92,9 @@ class Requirement
   /// superclass requirement, 'T : C' cannot be satisfied.
   bool canBeSatisfied() const;
 
+  /// Linear order on requirements in a generic signature.
+  int compare(const Requirement &other) const;
+
   SWIFT_DEBUG_DUMP;
   void dump(raw_ostream &out) const;
   void print(raw_ostream &os, const PrintOptions &opts) const;

lib/AST/GenericSignature.cpp

@@ -1430,3 +1430,105 @@ bool Requirement::canBeSatisfied() const {
 
   llvm_unreachable("Bad requirement kind");
 }
+
+/// Determine the canonical ordering of requirements.
+static unsigned getRequirementKindOrder(RequirementKind kind) {
+  switch (kind) {
+  case RequirementKind::Conformance: return 2;
+  case RequirementKind::Superclass: return 0;
+  case RequirementKind::SameType: return 3;
+  case RequirementKind::Layout: return 1;
+  }
+  llvm_unreachable("unhandled kind");
+}
+
+/// Linear order on requirements in a generic signature.
+int Requirement::compare(const Requirement &other) const {
+  int compareLHS =
+    compareDependentTypes(getFirstType(), other.getFirstType());
+
+  if (compareLHS != 0)
+    return compareLHS;
+
+  int compareKind = (getRequirementKindOrder(getKind()) -
+                     getRequirementKindOrder(other.getKind()));
+
+  if (compareKind != 0)
+    return compareKind;
+
+  // We should only have multiple conformance requirements.
+  assert(getKind() == RequirementKind::Conformance);
+
+  int compareProtos =
+    TypeDecl::compare(getProtocolDecl(), other.getProtocolDecl());
+
+  assert(compareProtos != 0 && "Duplicate conformance requirement");
+  return compareProtos;
+}
+
+/// Compare two associated types.
+int swift::compareAssociatedTypes(AssociatedTypeDecl *assocType1,
+                                  AssociatedTypeDecl *assocType2) {
+  // - by name.
+  if (int result = assocType1->getName().str().compare(
+                                              assocType2->getName().str()))
+    return result;
+
+  // Prefer an associated type with no overrides (i.e., an anchor) to one
+  // that has overrides.
+  bool hasOverridden1 = !assocType1->getOverriddenDecls().empty();
+  bool hasOverridden2 = !assocType2->getOverriddenDecls().empty();
+  if (hasOverridden1 != hasOverridden2)
+    return hasOverridden1 ? +1 : -1;
+
+  // - by protocol, so t_n_m.`P.T` < t_n_m.`Q.T` (given P < Q)
+  auto proto1 = assocType1->getProtocol();
+  auto proto2 = assocType2->getProtocol();
+  if (int compareProtocols = TypeDecl::compare(proto1, proto2))
+    return compareProtocols;
+
+  // Error case: if we have two associated types with the same name in the
+  // same protocol, just tie-break based on address.
+  if (assocType1 != assocType2)
+    return assocType1 < assocType2 ? -1 : +1;
+
+  return 0;
+}
+
+/// Canonical ordering for type parameters.
+int swift::compareDependentTypes(Type type1, Type type2) {
+  // Fast-path check for equality.
+  if (type1->isEqual(type2)) return 0;
+
+  // Ordering is as follows:
+  // - Generic params
+  auto gp1 = type1->getAs<GenericTypeParamType>();
+  auto gp2 = type2->getAs<GenericTypeParamType>();
+  if (gp1 && gp2)
+    return GenericParamKey(gp1) < GenericParamKey(gp2) ? -1 : +1;
+
+  // A generic parameter is always ordered before a nested type.
+  if (static_cast<bool>(gp1) != static_cast<bool>(gp2))
+    return gp1 ? -1 : +1;
+
+  // - Dependent members
+  auto depMemTy1 = type1->castTo<DependentMemberType>();
+  auto depMemTy2 = type2->castTo<DependentMemberType>();
+
+  // - by base, so t_0_n.`P.T` < t_1_m.`P.T`
+  if (int compareBases =
+        compareDependentTypes(depMemTy1->getBase(), depMemTy2->getBase()))
+    return compareBases;
+
+  // - by name, so t_n_m.`P.T` < t_n_m.`P.U`
+  if (int compareNames = depMemTy1->getName().str().compare(
+                                                  depMemTy2->getName().str()))
+    return compareNames;
+
+  auto *assocType1 = depMemTy1->getAssocType();
+  auto *assocType2 = depMemTy2->getAssocType();
+  if (int result = compareAssociatedTypes(assocType1, assocType2))
+    return result;
+
+  return 0;
+}

lib/AST/GenericSignatureBuilder.cpp

@@ -1979,35 +1979,6 @@ bool EquivalenceClass::isConformanceSatisfiedBySuperclass(
   return false;
 }
 
-/// Compare two associated types.
-static int compareAssociatedTypes(AssociatedTypeDecl *assocType1,
-                                  AssociatedTypeDecl *assocType2) {
-  // - by name.
-  if (int result = assocType1->getName().str().compare(
-                                              assocType2->getName().str()))
-    return result;
-
-  // Prefer an associated type with no overrides (i.e., an anchor) to one
-  // that has overrides.
-  bool hasOverridden1 = !assocType1->getOverriddenDecls().empty();
-  bool hasOverridden2 = !assocType2->getOverriddenDecls().empty();
-  if (hasOverridden1 != hasOverridden2)
-    return hasOverridden1 ? +1 : -1;
-
-  // - by protocol, so t_n_m.`P.T` < t_n_m.`Q.T` (given P < Q)
-  auto proto1 = assocType1->getProtocol();
-  auto proto2 = assocType2->getProtocol();
-  if (int compareProtocols = TypeDecl::compare(proto1, proto2))
-    return compareProtocols;
-
-  // Error case: if we have two associated types with the same name in the
-  // same protocol, just tie-break based on address.
-  if (assocType1 != assocType2)
-    return assocType1 < assocType2 ? -1 : +1;
-
-  return 0;
-}
-
 static void lookupConcreteNestedType(NominalTypeDecl *decl,
                                      Identifier name,
                                      SmallVectorImpl<TypeDecl *> &concreteDecls) {
@@ -2511,44 +2482,6 @@ auto PotentialArchetype::getRepresentative() const -> PotentialArchetype * {
   return result;
 }
 
-/// Canonical ordering for dependent types.
-int swift::compareDependentTypes(Type type1, Type type2) {
-  // Fast-path check for equality.
-  if (type1->isEqual(type2)) return 0;
-
-  // Ordering is as follows:
-  // - Generic params
-  auto gp1 = type1->getAs<GenericTypeParamType>();
-  auto gp2 = type2->getAs<GenericTypeParamType>();
-  if (gp1 && gp2)
-    return GenericParamKey(gp1) < GenericParamKey(gp2) ? -1 : +1;
-
-  // A generic parameter is always ordered before a nested type.
-  if (static_cast<bool>(gp1) != static_cast<bool>(gp2))
-    return gp1 ? -1 : +1;
-
-  // - Dependent members
-  auto depMemTy1 = type1->castTo<DependentMemberType>();
-  auto depMemTy2 = type2->castTo<DependentMemberType>();
-
-  // - by base, so t_0_n.`P.T` < t_1_m.`P.T`
-  if (int compareBases =
-        compareDependentTypes(depMemTy1->getBase(), depMemTy2->getBase()))
-    return compareBases;
-
-  // - by name, so t_n_m.`P.T` < t_n_m.`P.U`
-  if (int compareNames = depMemTy1->getName().str().compare(
-                                                  depMemTy2->getName().str()))
-    return compareNames;
-
-  auto *assocType1 = depMemTy1->getAssocType();
-  auto *assocType2 = depMemTy2->getAssocType();
-  if (int result = compareAssociatedTypes(assocType1, assocType2))
-    return result;
-
-  return 0;
-}
-
 /// Compare two dependent paths to determine which is better.
 static int compareDependentPaths(ArrayRef<AssociatedTypeDecl *> path1,
                                  ArrayRef<AssociatedTypeDecl *> path2) {
@@ -7915,43 +7848,9 @@ static Optional<Requirement> createRequirement(RequirementKind kind,
   }
 }
 
-/// Determine the canonical ordering of requirements.
-static unsigned getRequirementKindOrder(RequirementKind kind) {
-  switch (kind) {
-  case RequirementKind::Conformance: return 2;
-  case RequirementKind::Superclass: return 0;
-  case RequirementKind::SameType: return 3;
-  case RequirementKind::Layout: return 1;
-  }
-  llvm_unreachable("unhandled kind");
-}
-
 static int compareRequirements(const Requirement *lhsPtr,
                                const Requirement *rhsPtr) {
-  auto &lhs = *lhsPtr;
-  auto &rhs = *rhsPtr;
-
-  int compareLHS =
-    compareDependentTypes(lhs.getFirstType(), rhs.getFirstType());
-
-  if (compareLHS != 0)
-    return compareLHS;
-
-  int compareKind = (getRequirementKindOrder(lhs.getKind()) -
-                     getRequirementKindOrder(rhs.getKind()));
-
-  if (compareKind != 0)
-    return compareKind;
-
-  // We should only have multiple conformance requirements.
-  assert(lhs.getKind() == RequirementKind::Conformance);
-
-  int compareProtos =
-    TypeDecl::compare(lhs.getProtocolDecl(), rhs.getProtocolDecl());
-
-  assert(compareProtos != 0 && "Duplicate conformance requirement");
-
-  return compareProtos;
+  return lhsPtr->compare(*rhsPtr);
 }
 
 void GenericSignatureBuilder::enumerateRequirements(
@@ -8180,7 +8079,7 @@ static void checkGenericSignature(CanGenericSignature canSig,
              "Concrete subject type should not have any other requirements");
     }
 
-    assert(compareRequirements(&prevReqt, &reqt) < 0 &&
+    assert(prevReqt.compare(reqt) < 0 &&
            "Out-of-order requirements");
   }
 }

lib/AST/RequirementMachine/GenericSignatureQueries.cpp

@@ -575,35 +575,6 @@ RequirementMachine::getConformanceAccessPath(Type type,
   }
 }
 
-/// Compare two associated types.
-static int compareAssociatedTypes(AssociatedTypeDecl *assocType1,
-                                  AssociatedTypeDecl *assocType2) {
-  // - by name.
-  if (int result = assocType1->getName().str().compare(
-                                              assocType2->getName().str()))
-    return result;
-
-  // Prefer an associated type with no overrides (i.e., an anchor) to one
-  // that has overrides.
-  bool hasOverridden1 = !assocType1->getOverriddenDecls().empty();
-  bool hasOverridden2 = !assocType2->getOverriddenDecls().empty();
-  if (hasOverridden1 != hasOverridden2)
-    return hasOverridden1 ? +1 : -1;
-
-  // - by protocol, so t_n_m.`P.T` < t_n_m.`Q.T` (given P < Q)
-  auto proto1 = assocType1->getProtocol();
-  auto proto2 = assocType2->getProtocol();
-  if (int compareProtocols = TypeDecl::compare(proto1, proto2))
-    return compareProtocols;
-
-  // Error case: if we have two associated types with the same name in the
-  // same protocol, just tie-break based on address.
-  if (assocType1 != assocType2)
-    return assocType1 < assocType2 ? -1 : +1;
-
-  return 0;
-}
-
 static void lookupConcreteNestedType(NominalTypeDecl *decl,
                                      Identifier name,
                                      SmallVectorImpl<TypeDecl *> &concreteDecls) {