Merge pull request swiftlang#83768 from slavapestov/replace-covariant-result-type

Sema: Remove a bunch of usages of replaceCovariantResultType()

Author: slavapestov

include/swift/AST/Types.h

@@ -1337,16 +1337,11 @@ class alignas(1 << TypeAlignInBits) TypeBase
   /// argument labels removed.
   Type removeArgumentLabels(unsigned numArgumentLabels);
 
-  /// Replace the base type of the result type of the given function
-  /// type with a new result type, as per a DynamicSelf or other
-  /// covariant return transformation.  The optionality of the
-  /// existing result will be preserved.
-  ///
-  /// \param newResultType The new result type.
-  ///
-  /// \param uncurryLevel The number of uncurry levels to apply before
-  /// replacing the type. With uncurry level == 0, this simply
-  /// replaces the current type with the new result type.
+  /// Replace DynamicSelfType anywhere it appears in covariant position with
+  /// the given type.
+  Type replaceDynamicSelfType(Type newSelfType);
+
+  /// Deprecated in favor of the above.
   Type replaceCovariantResultType(Type newResultType,
                                   unsigned uncurryLevel);
 

include/swift/Sema/ConstraintSystem.h

@@ -4474,8 +4474,7 @@ class ConstraintSystem {
   Type getUnopenedTypeOfReference(VarDecl *value, Type baseType,
                                   DeclContext *UseDC,
                                   ConstraintLocator *locator,
-                                  bool wantInterfaceType = false,
-                                  bool adjustForPreconcurrency = true);
+                                  bool wantInterfaceType);
 
   /// Given the opened type and a pile of information about a member reference,
   /// determine the reference type of the member reference.

lib/AST/Type.cpp

@@ -1329,6 +1329,21 @@ Type TypeBase::removeArgumentLabels(unsigned numArgumentLabels) {
   return FunctionType::get(unlabeledParams, result, fnType->getExtInfo());
 }
 
+Type TypeBase::replaceDynamicSelfType(Type newSelfType) {
+  if (!hasDynamicSelfType())
+    return Type(this);
+
+  return Type(this).transformWithPosition(
+      TypePosition::Covariant,
+      [&](TypeBase *t, TypePosition pos) -> std::optional<Type> {
+      if (isa<DynamicSelfType>(t) &&
+          pos == TypePosition::Covariant) {
+        return newSelfType;
+      }
+    return std::nullopt;
+  });
+}
+
 Type TypeBase::replaceCovariantResultType(Type newResultType,
                                           unsigned uncurryLevel) {
   if (uncurryLevel == 0) {

lib/AST/TypeSubstitution.cpp

@@ -867,33 +867,26 @@ Type TypeBase::getTypeOfMember(const ValueDecl *member,
 
 Type TypeBase::adjustSuperclassMemberDeclType(const ValueDecl *baseDecl,
                                               const ValueDecl *derivedDecl,
-                                              Type memberType) {
+                                              Type type) {
   auto subs = SubstitutionMap::getOverrideSubstitutions(
       baseDecl, derivedDecl);
 
-  if (auto *genericMemberType = memberType->getAs<GenericFunctionType>()) {
-    memberType = FunctionType::get(genericMemberType->getParams(),
-                                   genericMemberType->getResult(),
-                                   genericMemberType->getExtInfo());
+  if (auto *genericMemberType = type->getAs<GenericFunctionType>()) {
+    type = genericMemberType->substGenericArgs(subs);
+  } else {
+    type = type.subst(subs);
   }
 
-  auto type = memberType.subst(subs);
   if (baseDecl->getDeclContext()->getSelfProtocolDecl())
     return type;
 
   if (auto *afd = dyn_cast<AbstractFunctionDecl>(baseDecl)) {
     type = type->replaceSelfParameterType(this);
-    if (afd->hasDynamicSelfResult())
-      type = type->replaceCovariantResultType(this, /*uncurryLevel=*/2);
-  } else if (auto *sd = dyn_cast<SubscriptDecl>(baseDecl)) {
-    if (sd->getElementInterfaceType()->hasDynamicSelfType())
-      type = type->replaceCovariantResultType(this, /*uncurryLevel=*/1);
-  } else if (auto *vd = dyn_cast<VarDecl>(baseDecl)) {
-    if (vd->getValueInterfaceType()->hasDynamicSelfType())
-      type = type->replaceCovariantResultType(this, /*uncurryLevel=*/0);
+    if (isa<ConstructorDecl>(afd))
+      return type->replaceCovariantResultType(this, /*uncurryLevel=*/2);
   }
 
-  return type;
+  return type->replaceDynamicSelfType(this);
 }
 
 //===----------------------------------------------------------------------===//

lib/SIL/Verifier/SILVerifier.cpp

@@ -4286,13 +4286,16 @@ class SILVerifier : public SILVerifierBase<SILVerifier> {
       if (fnDecl->hasDynamicSelfResult()) {
         auto anyObjectTy = C.getAnyObjectType();
         for (auto &result : results) {
-          auto newResultTy =
+          auto resultTy =
               result
                   .getReturnValueType(F.getModule(), methodTy,
-                                      F.getTypeExpansionContext())
-                  ->replaceCovariantResultType(anyObjectTy, 0);
-          result = SILResultInfo(newResultTy->getCanonicalType(),
-                                 result.getConvention());
+                                      F.getTypeExpansionContext());
+          if (resultTy->getOptionalObjectType())
+            resultTy = OptionalType::get(anyObjectTy)->getCanonicalType();
+          else
+            resultTy = anyObjectTy;
+
+          result = SILResultInfo(resultTy, result.getConvention());
         }
       }
     }

lib/SILGen/SILGenApply.cpp

@@ -148,10 +148,10 @@ getPartialApplyOfDynamicMethodFormalType(SILGenModule &SGM, SILDeclRef member,
 
   // Adjust the result type to replace dynamic-self with AnyObject.
   CanType resultType = completeMethodTy.getResult();
-  if (auto fnDecl = dyn_cast<FuncDecl>(member.getDecl())) {
-    if (fnDecl->hasDynamicSelfResult()) {
+  if (isa<FuncDecl>(member.getDecl())) {
+    if (resultType->hasDynamicSelfType()) {
       auto anyObjectTy = SGM.getASTContext().getAnyObjectType();
-      resultType = resultType->replaceCovariantResultType(anyObjectTy, 0)
+      resultType = resultType->replaceDynamicSelfType(anyObjectTy)
                              ->getCanonicalType();
     }
   }

lib/Sema/CSApply.cpp

@@ -1921,18 +1921,17 @@ namespace {
           base->setImplicit();
         }
 
-        const auto hasDynamicSelf =
-            varDecl->getValueInterfaceType()->hasDynamicSelfType();
+        const auto hasDynamicSelf = refTy->hasDynamicSelfType();
 
         auto memberRefExpr
           = new (ctx) MemberRefExpr(base, dotLoc, memberRef,
                                     memberLoc, Implicit, semantics);
         memberRefExpr->setIsSuper(isSuper);
 
         if (hasDynamicSelf) {
-          refTy = refTy->replaceCovariantResultType(containerTy, 1);
-          adjustedRefTy = adjustedRefTy->replaceCovariantResultType(
-              containerTy, 1);
+          refTy = refTy->replaceDynamicSelfType(containerTy);
+          adjustedRefTy = adjustedRefTy->replaceDynamicSelfType(
+              containerTy);
         }
 
         cs.setType(memberRefExpr, resultType(refTy));
@@ -2482,19 +2481,21 @@ namespace {
       if (!base)
         return nullptr;
 
-      const auto hasDynamicSelf =
-          subscript->getElementInterfaceType()->hasDynamicSelfType();
+      bool hasDynamicSelf = fullSubscriptTy->hasDynamicSelfType();
 
       // Form the subscript expression.
       auto subscriptExpr = SubscriptExpr::create(
           ctx, base, args, subscriptRef, isImplicit, semantics);
       cs.setType(subscriptExpr, fullSubscriptTy->getResult());
       subscriptExpr->setIsSuper(isSuper);
-      cs.setType(subscriptExpr,
-                 hasDynamicSelf
-                     ? fullSubscriptTy->getResult()->replaceCovariantResultType(
-                           containerTy, 0)
-                     : fullSubscriptTy->getResult());
+
+      if (!hasDynamicSelf) {
+        cs.setType(subscriptExpr, fullSubscriptTy->getResult());
+      } else {
+        cs.setType(subscriptExpr,
+                   fullSubscriptTy->getResult()
+                      ->replaceDynamicSelfType(containerTy));
+      }
 
       Expr *result = subscriptExpr;
       closeExistentials(result, locator);

lib/Sema/TypeCheckConcurrency.cpp

@@ -7908,6 +7908,10 @@ AnyFunctionType *swift::adjustFunctionTypeForConcurrency(
       (isa<AbstractFunctionDecl>(decl) &&
        cast<AbstractFunctionDecl>(decl)->hasImplicitSelfDecl()));
   if (!hasImplicitSelfDecl) {
+    // Fast path.
+    if (fnType->getExtInfo().getIsolation() == *funcIsolation)
+      return fnType;
+
     return fnType->withExtInfo(
         fnType->getExtInfo().withIsolation(*funcIsolation));
   }
@@ -7917,6 +7921,10 @@ AnyFunctionType *swift::adjustFunctionTypeForConcurrency(
   if (!innerFnType)
     return fnType;
 
+  // Fast path.
+  if (innerFnType->getExtInfo().getIsolation() == *funcIsolation)
+    return fnType;
+
   // Update the inner function type with the isolation.
   innerFnType = innerFnType->withExtInfo(
       innerFnType->getExtInfo().withIsolation(*funcIsolation));

lib/Sema/TypeOfReference.cpp

@@ -651,8 +651,7 @@ ClosureIsolatedByPreconcurrency::operator()(const ClosureExpr *expr) const {
 
 Type ConstraintSystem::getUnopenedTypeOfReference(
     VarDecl *value, Type baseType, DeclContext *UseDC,
-    ConstraintLocator *locator, bool wantInterfaceType,
-    bool adjustForPreconcurrency) {
+    ConstraintLocator *locator, bool wantInterfaceType) {
   Type requestedType;
   if (Type type = getTypeIfAvailable(value)) {
     requestedType = type;
@@ -671,14 +670,6 @@ Type ConstraintSystem::getUnopenedTypeOfReference(
   if (auto *expansion = requestedType->getAs<PackExpansionType>())
     requestedType = expansion->getPatternType();
 
-  // Adjust the type for concurrency if requested.
-  if (adjustForPreconcurrency) {
-    requestedType = adjustVarTypeForConcurrency(
-        requestedType, value, UseDC,
-        GetClosureType{*this},
-        ClosureIsolatedByPreconcurrency{*this});
-  }
-
   // If we're dealing with contextual types, and we referenced this type from
   // a different context, map the type.
   if (!wantInterfaceType && requestedType->hasArchetype()) {
@@ -1019,11 +1010,11 @@ ConstraintSystem::getTypeOfReference(ValueDecl *value,
 
     // If this is a method whose result type is dynamic Self, replace
     // DynamicSelf with the actual object type.
-    if (func->getResultInterfaceType()->hasDynamicSelfType()) {
+    if (openedType->hasDynamicSelfType()) {
       auto params = openedType->getParams();
       assert(params.size() == 1);
       Type selfTy = params.front().getPlainType()->getMetatypeInstanceType();
-      openedType = openedType->replaceCovariantResultType(selfTy, 2)
+      openedType = openedType->replaceDynamicSelfType(selfTy)
                         ->castTo<FunctionType>();
     }
 
@@ -1057,15 +1048,6 @@ ConstraintSystem::getTypeOfReference(ValueDecl *value,
         *this, funcDecl, functionRefInfo, openedType->castTo<FunctionType>(),
         locator, preparedOverload);
 
-    auto origOpenedType = openedType;
-    if (!isRequirementOrWitness(locator)) {
-      unsigned numApplies = getNumApplications(/*hasAppliedSelf*/ false,
-                                               functionRefInfo);
-      openedType = adjustFunctionTypeForConcurrency(
-          origOpenedType->castTo<FunctionType>(), /*baseType=*/Type(), funcDecl,
-          useDC, numApplies, false, replacements, locator, preparedOverload);
-    }
-
     if (isForCodeCompletion() && openedType->hasError()) {
       // In code completion, replace error types by placeholder types so we can
       // match the types we know instead of bailing out completely.
@@ -1076,6 +1058,15 @@ ConstraintSystem::getTypeOfReference(ValueDecl *value,
     // If we opened up any type variables, record the replacements.
     recordOpenedTypes(locator, replacements, preparedOverload);
 
+    auto origOpenedType = openedType;
+    if (!isRequirementOrWitness(locator)) {
+      unsigned numApplies = getNumApplications(/*hasAppliedSelf*/ false,
+                                               functionRefInfo);
+      openedType = adjustFunctionTypeForConcurrency(
+          origOpenedType->castTo<FunctionType>(), /*baseType=*/Type(), funcDecl,
+          useDC, numApplies, false, replacements, locator, preparedOverload);
+    }
+
     return { origOpenedType, openedType, origOpenedType, openedType, Type() };
   }
 
@@ -1128,12 +1119,16 @@ ConstraintSystem::getTypeOfReference(ValueDecl *value,
   auto *varDecl = cast<VarDecl>(value);
 
   // Determine the type of the value, opening up that type if necessary.
-  // FIXME: @preconcurrency
   bool wantInterfaceType = !varDecl->getDeclContext()->isLocalContext();
   Type valueType =
       getUnopenedTypeOfReference(varDecl, Type(), useDC, 
                                  getConstraintLocator(locator),
                                  wantInterfaceType);
+  // FIXME: Adjust the type for concurrency if requested.
+  valueType = adjustVarTypeForConcurrency(
+      valueType, varDecl, useDC,
+      GetClosureType{*this},
+      ClosureIsolatedByPreconcurrency{*this});
 
   Type thrownErrorType;
   if (auto accessor = varDecl->getEffectfulGetAccessor()) {
@@ -1476,19 +1471,13 @@ Type ConstraintSystem::getMemberReferenceTypeFromOpenedType(
         getDynamicSelfReplacementType(baseObjTy, value, locator);
 
     if (auto func = dyn_cast<AbstractFunctionDecl>(value)) {
-      if (func->hasDynamicSelfResult() &&
+      if (isa<ConstructorDecl>(func) &&
           !baseObjTy->getOptionalObjectType()) {
         type = type->replaceCovariantResultType(replacementTy, 2);
       }
-    } else if (auto *decl = dyn_cast<SubscriptDecl>(value)) {
-      if (decl->getElementInterfaceType()->hasDynamicSelfType()) {
-        type = type->replaceCovariantResultType(replacementTy, 2);
-      }
-    } else if (auto *decl = dyn_cast<VarDecl>(value)) {
-      if (decl->getValueInterfaceType()->hasDynamicSelfType()) {
-        type = type->replaceCovariantResultType(replacementTy, 1);
-      }
     }
+
+    type = type->replaceDynamicSelfType(replacementTy);
   }
 
   // Check if we need to apply a layer of optionality to the uncurried type.
@@ -1724,8 +1713,7 @@ DeclReferenceType ConstraintSystem::getTypeOfMemberReference(
 
       refType = getUnopenedTypeOfReference(cast<VarDecl>(value), baseTy, useDC,
                                            locator,
-                                           /*wantInterfaceType=*/true,
-                                           /*adjustForPreconcurrency=*/false);
+                                           /*wantInterfaceType=*/true);
     }
 
     auto selfTy = outerDC->getSelfInterfaceType();