Merge pull request #83858 from slavapestov/covariant-result-type-part-2

slavapestov · web-flow · commit a5a8cf4a366d · 2025-08-28T10:07:13.000-04:00
AST: Continue process of removing replaceCovariantResultType()
diff --git a/include/swift/AST/Types.h b/include/swift/AST/Types.h
@@ -1344,6 +1344,9 @@ class alignas(1 << TypeAlignInBits) TypeBase
   /// the given type.
   Type replaceDynamicSelfType(Type newSelfType);
 
+  /// Hack to deal with ConstructorDecl interface types.
+  Type withCovariantResultType();
+
   /// Deprecated in favor of the above.
   Type replaceCovariantResultType(Type newResultType,
                                   unsigned uncurryLevel);
diff --git a/lib/AST/ASTContext.cpp b/lib/AST/ASTContext.cpp
@@ -4076,7 +4076,7 @@ AnyFunctionType::Param swift::computeSelfParam(AbstractFunctionDecl *AFD,
     // Methods returning 'Self' have a dynamic 'self'.
     //
     // FIXME: All methods of non-final classes should have this.
-    else if (wantDynamicSelf && FD->hasDynamicSelfResult())
+    else if (wantDynamicSelf && FD->getResultInterfaceType()->hasDynamicSelfType())
       isDynamicSelf = true;
 
   } else if (auto *CD = dyn_cast<ConstructorDecl>(AFD)) {
diff --git a/lib/AST/Type.cpp b/lib/AST/Type.cpp
@@ -1357,6 +1357,42 @@ Type TypeBase::replaceDynamicSelfType(Type newSelfType) {
   });
 }
 
+Type TypeBase::withCovariantResultType() {
+  // Unwrap the outer function type.
+  auto fnType = this->castTo<AnyFunctionType>();
+  ASSERT(fnType->getParams().size() == 1);
+
+  // Unwrap the inner function type.
+  auto resultFnType = fnType->getResult()->castTo<FunctionType>();
+  auto resultType = resultFnType->getResult();
+
+  bool wasOptional = false;
+  if (auto objectType = resultType->getOptionalObjectType()) {
+    wasOptional = true;
+    resultType = objectType;
+  }
+
+  ASSERT(resultType->getClassOrBoundGenericClass());
+  resultType = DynamicSelfType::get(resultType, getASTContext());
+
+  // Rebuild the inner function type.
+  if (wasOptional)
+    resultType = OptionalType::get(resultType);
+
+  resultFnType = FunctionType::get(resultFnType->getParams(), resultType,
+                                   resultFnType->getExtInfo());
+
+  // Rebuild the outer function type.
+  if (auto genericFn = dyn_cast<GenericFunctionType>(fnType)) {
+    return GenericFunctionType::get(genericFn->getGenericSignature(),
+                                    fnType->getParams(), resultFnType,
+                                    fnType->getExtInfo());
+  }
+  
+  return FunctionType::get(fnType->getParams(), resultFnType,
+                           fnType->getExtInfo());
+}
+
 Type TypeBase::replaceCovariantResultType(Type newResultType,
                                           unsigned uncurryLevel) {
   if (uncurryLevel == 0) {
diff --git a/lib/AST/TypeSubstitution.cpp b/lib/AST/TypeSubstitution.cpp
@@ -885,8 +885,9 @@ Type TypeBase::adjustSuperclassMemberDeclType(const ValueDecl *baseDecl,
 
   if (auto *afd = dyn_cast<AbstractFunctionDecl>(baseDecl)) {
     type = type->replaceSelfParameterType(this);
-    if (isa<ConstructorDecl>(afd))
-      return type->replaceCovariantResultType(this, /*uncurryLevel=*/2);
+    if (isa<ConstructorDecl>(afd) &&
+        afd->getDeclContext()->getSelfClassDecl())
+      type = type->withCovariantResultType();
   }
 
   return type->replaceDynamicSelfType(this);
diff --git a/lib/PrintAsClang/DeclAndTypePrinter.cpp b/lib/PrintAsClang/DeclAndTypePrinter.cpp
@@ -1250,7 +1250,8 @@ class DeclAndTypePrinter::Implementation
     // Constructors and methods returning DynamicSelf return
     // instancetype.
     if (isa<ConstructorDecl>(AFD) ||
-        (isa<FuncDecl>(AFD) && cast<FuncDecl>(AFD)->hasDynamicSelfResult() &&
+        (isa<FuncDecl>(AFD) &&
+         cast<FuncDecl>(AFD)->getResultInterfaceType()->hasDynamicSelfType() &&
          !AFD->hasAsync())) {
       if (errorConvention && errorConvention->stripsResultOptionality()) {
         printNullability(OTK_Optional, NullabilityPrintKind::ContextSensitive);
diff --git a/lib/SIL/Verifier/SILVerifier.cpp b/lib/SIL/Verifier/SILVerifier.cpp
@@ -4283,7 +4283,7 @@ class SILVerifier : public SILVerifierBase<SILVerifier> {
     // If the method returns dynamic Self, substitute AnyObject for the
     // result type.
     if (auto fnDecl = dyn_cast<FuncDecl>(method.getDecl())) {
-      if (fnDecl->hasDynamicSelfResult()) {
+      if (fnDecl->getResultInterfaceType()->hasDynamicSelfType()) {
         auto anyObjectTy = C.getAnyObjectType();
         for (auto &result : results) {
           auto resultTy =
diff --git a/lib/Sema/CSApply.cpp b/lib/Sema/CSApply.cpp
@@ -1403,23 +1403,25 @@ namespace {
       // special handling.
       if (baseExpr) {
         if (auto *fnDecl = dyn_cast<AbstractFunctionDecl>(declOrClosure)) {
-          if (fnDecl->hasDynamicSelfResult()) {
-            Type convTy;
-
-            if (cs.getType(baseExpr)->hasOpenedExistential()) {
-              // FIXME: Sometimes we need to convert to an opened existential
-              // first, because CovariantReturnConversionExpr does not support
-              // direct conversions from a class C to an existential C & P.
-              convTy = cs.getType(baseExpr)->getMetatypeInstanceType();
-              convTy =
-                  thunkTy->getResult()->replaceCovariantResultType(convTy, 0);
-            } else {
-              convTy = thunkTy->getResult();
-            }
+          if (fnDecl->getDeclContext()->getSelfClassDecl()) {
+            if (fnDecl->hasDynamicSelfResult()) {
+              Type convTy;
+
+              if (cs.getType(baseExpr)->hasOpenedExistential()) {
+                // FIXME: Sometimes we need to convert to an opened existential
+                // first, because CovariantReturnConversionExpr does not support
+                // direct conversions from a class C to an existential C & P.
+                convTy = cs.getType(baseExpr)->getMetatypeInstanceType();
+                if (thunkTy->getResult()->getOptionalObjectType())
+                  convTy = OptionalType::get(thunkTy);
+              } else {
+                convTy = thunkTy->getResult();
+              }
 
-            if (!thunkBody->getType()->isEqual(convTy)) {
-              thunkBody = cs.cacheType(
-                  new (ctx) CovariantReturnConversionExpr(thunkBody, convTy));
+              if (!thunkBody->getType()->isEqual(convTy)) {
+                thunkBody = cs.cacheType(
+                    new (ctx) CovariantReturnConversionExpr(thunkBody, convTy));
+              }
             }
           }
         }
@@ -1964,9 +1966,10 @@ namespace {
 
       auto *func = dyn_cast<FuncDecl>(member);
       if (func && func->getResultInterfaceType()->hasDynamicSelfType()) {
-        refTy = refTy->replaceCovariantResultType(containerTy, 2);
-        adjustedRefTy = adjustedRefTy->replaceCovariantResultType(
-            containerTy, 2);
+        ASSERT(refTy->hasDynamicSelfType());
+        refTy = refTy->replaceDynamicSelfType(containerTy);
+        adjustedRefTy = adjustedRefTy->replaceDynamicSelfType(
+            containerTy);
       }
 
       // Handle all other references.
@@ -2110,10 +2113,9 @@ namespace {
       //
       // Note: For unbound references this is handled inside the thunk.
       if (!isUnboundInstanceMember &&
-          !member->getDeclContext()->getSelfProtocolDecl()) {
+          member->getDeclContext()->getSelfClassDecl()) {
         if (auto func = dyn_cast<AbstractFunctionDecl>(member)) {
-          if (func->hasDynamicSelfResult() &&
-              !baseTy->getOptionalObjectType()) {
+          if (func->hasDynamicSelfResult()) {
             // FIXME: Once CovariantReturnConversionExpr (unchecked_ref_cast)
             // supports a class existential dest., consider using the opened
             // type directly to avoid recomputing the 'Self' replacement and
@@ -2543,9 +2545,9 @@ namespace {
           new (ctx) OtherConstructorDeclRefExpr(ref, loc, implicit, resultTy));
 
       // Wrap in covariant `Self` return if needed.
-      if (selfTy->hasReferenceSemantics()) {
-        auto covariantTy = resultTy->replaceCovariantResultType(
-          cs.getType(base)->getWithoutSpecifierType(), 2);
+      if (ref.getDecl()->getDeclContext()->getSelfClassDecl()) {
+        auto covariantTy = resultTy->withCovariantResultType()
+          ->replaceDynamicSelfType(cs.getType(base)->getWithoutSpecifierType());
         if (!covariantTy->isEqual(resultTy))
           ctorRef = cs.cacheType(
                new (ctx) CovariantFunctionConversionExpr(ctorRef, covariantTy));
diff --git a/lib/Sema/CSSimplify.cpp b/lib/Sema/CSSimplify.cpp
@@ -13210,18 +13210,14 @@ bool ConstraintSystem::simplifyAppliedOverloadsImpl(
 
   /// The common result type amongst all function overloads.
   Type commonResultType;
-  auto updateCommonResultType = [&](Type choiceType) {
-    auto markFailure = [&] {
-      commonResultType = ErrorType::get(getASTContext());
-    };
 
-    auto choiceFnType = choiceType->getAs<FunctionType>();
-    if (!choiceFnType)
-      return markFailure();
+  auto markFailure = [&] {
+    commonResultType = ErrorType::get(getASTContext());
+  };
 
+  auto updateCommonResultType = [&](Type choiceResultType) {
     // For now, don't attempt to establish a common result type when there
     // are type parameters.
-    Type choiceResultType = choiceFnType->getResult();
     if (choiceResultType->hasTypeParameter())
       return markFailure();
 
@@ -13359,8 +13355,28 @@ bool ConstraintSystem::simplifyAppliedOverloadsImpl(
             choiceType = objectType;
         }
 
-        // If we have a function type, we can compute a common result type.
-        updateCommonResultType(choiceType);
+        if (auto *choiceFnType = choiceType->getAs<FunctionType>()) {
+          if (isa<ConstructorDecl>(choice.getDecl())) {
+            auto choiceResultType = choice.getBaseType()
+                                        ->getRValueType()
+                                        ->getMetatypeInstanceType();
+
+            if (choiceResultType->getOptionalObjectType()) {
+              hasUnhandledConstraints = true;
+              return true;
+            }
+
+            if (choiceFnType->getResult()->getOptionalObjectType())
+              choiceResultType = OptionalType::get(choiceResultType);
+
+            updateCommonResultType(choiceResultType);
+          } else {
+            updateCommonResultType(choiceFnType->getResult());
+          }
+        } else {
+          markFailure();
+        }
+
         return true;
       });
 
diff --git a/lib/Sema/MiscDiagnostics.cpp b/lib/Sema/MiscDiagnostics.cpp
@@ -6808,13 +6808,15 @@ TypeChecker::omitNeedlessWords(AbstractFunctionDecl *afd) {
   // Handle contextual type, result type, and returnsSelf.
   Type contextType = afd->getDeclContext()->getDeclaredInterfaceType();
   Type resultType;
-  bool returnsSelf = afd->hasDynamicSelfResult();
+  bool returnsSelf;
 
   if (auto func = dyn_cast<FuncDecl>(afd)) {
     resultType = func->getResultInterfaceType();
     resultType = func->mapTypeIntoContext(resultType);
+    returnsSelf = func->getResultInterfaceType()->hasDynamicSelfType();
   } else if (isa<ConstructorDecl>(afd)) {
     resultType = contextType;
+    returnsSelf = true;
   }
 
   // Figure out the first parameter name.
diff --git a/lib/Sema/TypeCheckAttr.cpp b/lib/Sema/TypeCheckAttr.cpp
@@ -6641,21 +6641,21 @@ typecheckDifferentiableAttrforDecl(AbstractFunctionDecl *original,
     // Dynamic `Self` is supported only as a single top-level result for class
     // members. JVP/VJP functions returning `(Self, ...)` tuples would not
     // type-check.
-    bool diagnoseDynamicSelfResult = original->hasDynamicSelfResult();
-    if (diagnoseDynamicSelfResult) {
-      // Diagnose class initializers in non-final classes.
-      if (isa<ConstructorDecl>(original)) {
-        if (!classDecl->isSemanticallyFinal()) {
-          diags.diagnose(
-              attr->getLocation(),
-              diag::differentiable_attr_nonfinal_class_init_unsupported,
-              classDecl->getDeclaredInterfaceType());
-          attr->setInvalid();
-          return nullptr;
-        }
+    // Diagnose class initializers in non-final classes.
+    if (isa<ConstructorDecl>(original)) {
+      if (!classDecl->isSemanticallyFinal()) {
+        diags.diagnose(
+            attr->getLocation(),
+            diag::differentiable_attr_nonfinal_class_init_unsupported,
+            classDecl->getDeclaredInterfaceType());
+        attr->setInvalid();
+        return nullptr;
       }
+    }
+
+    if (auto *funcDecl = dyn_cast<FuncDecl>(original)) {
       // Diagnose all other declarations returning dynamic `Self`.
-      else {
+      if (funcDecl->getResultInterfaceType()->hasDynamicSelfType()) {
         diags.diagnose(
             attr->getLocation(),
             diag::
@@ -7035,19 +7035,19 @@ static bool typeCheckDerivativeAttr(DerivativeAttr *attr) {
     // Dynamic `Self` is supported only as a single top-level result for class
     // members. JVP/VJP functions returning `(Self, ...)` tuples would not
     // type-check.
-    bool diagnoseDynamicSelfResult = originalAFD->hasDynamicSelfResult();
-    if (diagnoseDynamicSelfResult) {
+    if (isa<ConstructorDecl>(originalAFD)) {
       // Diagnose class initializers in non-final classes.
-      if (isa<ConstructorDecl>(originalAFD)) {
-        if (!classDecl->isSemanticallyFinal()) {
-          diags.diagnose(attr->getLocation(),
-                         diag::derivative_attr_nonfinal_class_init_unsupported,
-                         classDecl->getDeclaredInterfaceType());
-          return true;
-        }
+      if (!classDecl->isSemanticallyFinal()) {
+        diags.diagnose(attr->getLocation(),
+                       diag::derivative_attr_nonfinal_class_init_unsupported,
+                       classDecl->getDeclaredInterfaceType());
+        return true;
       }
+    }
+
+    if (auto *FD = dyn_cast<FuncDecl>(originalAFD)) {
       // Diagnose all other declarations returning dynamic `Self`.
-      else {
+      if (FD->getResultInterfaceType()->hasDynamicSelfType()) {
         diags.diagnose(
             attr->getLocation(),
             diag::derivative_attr_class_member_dynamic_self_result_unsupported,
diff --git a/lib/Sema/TypeCheckDeclObjC.cpp b/lib/Sema/TypeCheckDeclObjC.cpp
@@ -855,7 +855,7 @@ bool swift::isRepresentableInLanguage(
 
     // The completion handler transformation cannot properly represent a
     // dynamic 'Self' type, so disallow @objc for such methods.
-    if (FD->hasDynamicSelfResult()) {
+    if (FD->getResultInterfaceType()->hasDynamicSelfType()) {
       AFD->diagnose(diag::async_objc_dynamic_self)
           .highlight(AFD->getAsyncLoc())
           .limitBehavior(behavior);
diff --git a/lib/Sema/TypeCheckProtocol.cpp b/lib/Sema/TypeCheckProtocol.cpp
@@ -4246,8 +4246,10 @@ void ConformanceChecker::checkNonFinalClassWitness(ValueDecl *requirement,
     // by holding onto Self accordingly.
     if (witness->getDeclContext()->getSelfClassDecl()) {
       const bool hasDynamicSelfResult = [&] {
-        if (auto func = dyn_cast<AbstractFunctionDecl>(witness)) {
-          return func->hasDynamicSelfResult();
+        if (isa<ConstructorDecl>(witness)) {
+          return true;
+        } else if (auto func = dyn_cast<FuncDecl>(witness)) {
+          return func->getResultInterfaceType()->hasDynamicSelfType();
         } else if (auto var = dyn_cast<VarDecl>(witness)) {
           return var->getInterfaceType()->hasDynamicSelfType();
         }
diff --git a/lib/Sema/TypeOfReference.cpp b/lib/Sema/TypeOfReference.cpp
diff --git a/test/Constraints/pack-expansion-expressions.swift b/test/Constraints/pack-expansion-expressions.swift
diff --git a/test/IDE/complete_init.swift b/test/IDE/complete_init.swift
diff --git a/test/decl/protocol/conforms/typed_throws.swift b/test/decl/protocol/conforms/typed_throws.swift
diff --git a/test/decl/typealias/generic.swift b/test/decl/typealias/generic.swift
