Sema: Remove ConstraintKind::SelfObjectOfProtocol

Author: slavapestov

include/swift/Sema/Constraint.h

@@ -92,14 +92,6 @@ enum class ConstraintKind : char {
   LiteralConformsTo,
   /// A checked cast from the first type to the second.
   CheckedCast,
-  /// The first type can act as the Self type of the second type (which
-  /// is a protocol).
-  ///
-  /// This constraint is slightly looser than a conforms-to constraint, because
-  /// an existential can be used as the Self of any protocol within the
-  /// existential, even if it doesn't conform to that protocol (e.g., due to
-  /// the use of associated types).
-  SelfObjectOfProtocol,
   /// Both types are function types. The first function type's
   /// input is the value being passed to the function and its output
   /// is a type variable that describes the output. The second
@@ -690,7 +682,6 @@ class Constraint final : public llvm::ilist_node<Constraint>,
     case ConstraintKind::LiteralConformsTo:
     case ConstraintKind::TransitivelyConformsTo:
     case ConstraintKind::CheckedCast:
-    case ConstraintKind::SelfObjectOfProtocol:
     case ConstraintKind::ApplicableFunction:
     case ConstraintKind::DynamicCallableApplicableFunction:
     case ConstraintKind::BindOverload:

include/swift/Sema/ConstraintSystem.h

@@ -4720,10 +4720,10 @@ class ConstraintSystem {
   /// Subroutine of \c matchTypes(), which matches up a value to an
   /// existential type.
   ///
-  /// \param kind Either ConstraintKind::SelfObjectOfProtocol or
-  /// ConstraintKind::ConformsTo. Usually this uses SelfObjectOfProtocol,
-  /// but when matching the instance type of a metatype with the instance type
-  /// of an existential metatype, since we want an actual conformance check.
+  /// \param kind Either ConstraintKind::Subtype or ConstraintKind::ConformsTo.
+  /// Usually this uses Subtype, but when matching the instance type of a
+  /// metatype with the instance type of an existential metatype, since we
+  /// want an actual conformance check.
   TypeMatchResult matchExistentialTypes(Type type1, Type type2,
                                         ConstraintKind kind,
                                         TypeMatchOptions flags,
@@ -4930,7 +4930,7 @@ class ConstraintSystem {
   ///
   /// \param type The type being tested.
   /// \param protocol The protocol to which the type should conform.
-  /// \param kind Either ConstraintKind::SelfObjectOfProtocol or
+  /// \param kind Either ConstraintKind::Subtype or
   /// ConstraintKind::ConformsTo.
   /// \param locator Locator describing where this constraint occurred.
   SolutionKind simplifyConformsToConstraint(Type type, ProtocolDecl *protocol,

lib/Sema/CSBindings.cpp

@@ -1873,8 +1873,7 @@ void PotentialBindings::infer(Constraint *constraint) {
     DelayedBy.push_back(constraint);
     break;
 
-  case ConstraintKind::ConformsTo:
-  case ConstraintKind::SelfObjectOfProtocol: {
+  case ConstraintKind::ConformsTo: {
     auto protocolTy = constraint->getSecondType();
     if (protocolTy->is<ProtocolType>())
       Protocols.push_back(constraint);
@@ -1985,7 +1984,6 @@ void PotentialBindings::retract(Constraint *constraint) {
 
   switch (constraint->getKind()) {
   case ConstraintKind::ConformsTo:
-  case ConstraintKind::SelfObjectOfProtocol:
     Protocols.erase(llvm::remove_if(Protocols, isMatchingConstraint),
                     Protocols.end());
     break;

lib/Sema/CSSimplify.cpp

@@ -2147,7 +2147,6 @@ ConstraintSystem::matchTupleTypes(TupleType *tuple1, TupleType *tuple2,
   case ConstraintKind::KeyPathApplication:
   case ConstraintKind::LiteralConformsTo:
   case ConstraintKind::OptionalObject:
-  case ConstraintKind::SelfObjectOfProtocol:
   case ConstraintKind::UnresolvedValueMember:
   case ConstraintKind::ValueMember:
   case ConstraintKind::ValueWitness:
@@ -2509,7 +2508,6 @@ static bool matchFunctionRepresentations(FunctionType::ExtInfo einfo1,
   case ConstraintKind::KeyPathApplication:
   case ConstraintKind::LiteralConformsTo:
   case ConstraintKind::OptionalObject:
-  case ConstraintKind::SelfObjectOfProtocol:
   case ConstraintKind::UnresolvedValueMember:
   case ConstraintKind::ValueMember:
   case ConstraintKind::ValueWitness:
@@ -3154,7 +3152,6 @@ ConstraintSystem::matchFunctionTypes(FunctionType *func1, FunctionType *func2,
   case ConstraintKind::KeyPathApplication:
   case ConstraintKind::LiteralConformsTo:
   case ConstraintKind::OptionalObject:
-  case ConstraintKind::SelfObjectOfProtocol:
   case ConstraintKind::UnresolvedValueMember:
   case ConstraintKind::ValueMember:
   case ConstraintKind::ValueWitness:
@@ -3981,8 +3978,8 @@ ConstraintSystem::matchExistentialTypes(Type type1, Type type2,
   }
 
   if (layout.explicitSuperclass) {
-    auto subKind = std::min(ConstraintKind::Subtype, kind);
-    auto result = matchTypes(type1, layout.explicitSuperclass, subKind,
+    auto result = matchTypes(type1, layout.explicitSuperclass,
+                             ConstraintKind::Subtype,
                              subflags, locator);
     if (result.isFailure())
       return result;
@@ -6957,7 +6954,6 @@ ConstraintSystem::matchTypes(Type type1, Type type2, ConstraintKind kind,
     case ConstraintKind::KeyPathApplication:
     case ConstraintKind::LiteralConformsTo:
     case ConstraintKind::OptionalObject:
-    case ConstraintKind::SelfObjectOfProtocol:
     case ConstraintKind::UnresolvedValueMember:
     case ConstraintKind::ValueMember:
     case ConstraintKind::ValueWitness:
@@ -8468,7 +8464,7 @@ ConstraintSystem::SolutionKind ConstraintSystem::simplifyConformsToConstraint(
   // conform -- they only need to contain the protocol, so check that
   // separately.
   switch (kind) {
-  case ConstraintKind::SelfObjectOfProtocol: {
+  case ConstraintKind::Subtype: {
     auto conformance = TypeChecker::containsProtocol(
         type, protocol, /*allowMissing=*/true);
     if (conformance) {
@@ -14268,7 +14264,7 @@ ConstraintSystem::simplifyRestrictedConstraintImpl(
   case ConversionRestrictionKind::Existential:
     addContextualScore();
     return matchExistentialTypes(type1, type2,
-                                 ConstraintKind::SelfObjectOfProtocol,
+                                 ConstraintKind::Subtype,
                                  subflags, locator);
 
   // for $< in { <, <c, <oc }:
@@ -15535,7 +15531,6 @@ ConstraintSystem::addConstraintImpl(ConstraintKind kind, Type first,
 
   case ConstraintKind::ConformsTo:
   case ConstraintKind::LiteralConformsTo:
-  case ConstraintKind::SelfObjectOfProtocol:
     return simplifyConformsToConstraint(first, second, kind, locator,
                                         subflags);
 
@@ -16066,7 +16061,6 @@ ConstraintSystem::simplifyConstraint(const Constraint &constraint) {
 
   case ConstraintKind::ConformsTo:
   case ConstraintKind::LiteralConformsTo:
-  case ConstraintKind::SelfObjectOfProtocol:
     return simplifyConformsToConstraint(
         constraint.getFirstType(), constraint.getSecondType(),
         constraint.getKind(), constraint.getLocator(), std::nullopt);

lib/Sema/Constraint.cpp

@@ -70,7 +70,6 @@ Constraint::Constraint(ConstraintKind Kind, Type First, Type Second,
   case ConstraintKind::LiteralConformsTo:
   case ConstraintKind::TransitivelyConformsTo:
   case ConstraintKind::CheckedCast:
-  case ConstraintKind::SelfObjectOfProtocol:
   case ConstraintKind::DynamicTypeOf:
   case ConstraintKind::EscapableFunctionOf:
   case ConstraintKind::OpenedExistentialOf:
@@ -151,7 +150,6 @@ Constraint::Constraint(ConstraintKind Kind, Type First, Type Second, Type Third,
   case ConstraintKind::LiteralConformsTo:
   case ConstraintKind::TransitivelyConformsTo:
   case ConstraintKind::CheckedCast:
-  case ConstraintKind::SelfObjectOfProtocol:
   case ConstraintKind::DynamicTypeOf:
   case ConstraintKind::EscapableFunctionOf:
   case ConstraintKind::OpenedExistentialOf:
@@ -294,7 +292,6 @@ Constraint::Constraint(ASTNode node, ContextualTypeInfo context,
 ProtocolDecl *Constraint::getProtocol() const {
   assert((Kind == ConstraintKind::ConformsTo ||
           Kind == ConstraintKind::LiteralConformsTo ||
-          Kind == ConstraintKind::SelfObjectOfProtocol ||
           Kind == ConstraintKind::TransitivelyConformsTo)
           && "Not a conformance constraint");
   return Types.Second->castTo<ProtocolType>()->getDecl();
@@ -394,7 +391,6 @@ void Constraint::print(llvm::raw_ostream &Out, SourceManager *sm,
   case ConstraintKind::LiteralConformsTo: Out << " literal conforms to "; break;
   case ConstraintKind::TransitivelyConformsTo: Out << " transitive conformance to "; break;
   case ConstraintKind::CheckedCast: Out << " checked cast to "; break;
-  case ConstraintKind::SelfObjectOfProtocol: Out << " Self type of "; break;
   case ConstraintKind::ApplicableFunction: Out << " applicable fn "; break;
   case ConstraintKind::DynamicCallableApplicableFunction:
       Out << " dynamic callable applicable fn "; break;
@@ -682,7 +678,6 @@ gatherReferencedTypeVars(Constraint *constraint,
   case ConstraintKind::ConformsTo:
   case ConstraintKind::LiteralConformsTo:
   case ConstraintKind::TransitivelyConformsTo:
-  case ConstraintKind::SelfObjectOfProtocol:
   case ConstraintKind::OneWayEqual:
   case ConstraintKind::OneWayBindParam:
   case ConstraintKind::FallbackType:
@@ -751,8 +746,7 @@ Constraint *Constraint::create(ConstraintSystem &cs, ConstraintKind kind,
 
   // Conformance constraints expect an existential on the right-hand side.
   assert((kind != ConstraintKind::ConformsTo &&
-          kind != ConstraintKind::TransitivelyConformsTo &&
-          kind != ConstraintKind::SelfObjectOfProtocol) ||
+          kind != ConstraintKind::TransitivelyConformsTo) ||
          second->isExistentialType());
 
   // Literal protocol conformances expect a protocol.