[5.9][Sema/SILGen] InitAccessors: A few improvements and bug fixes

lib/Parse/ParseDecl.cpp

@@ -7109,6 +7109,7 @@ struct Parser::ParsedAccessors {
 
   /// Find the first accessor that can be used to perform mutation.
   AccessorDecl *findFirstMutator() const {
+    if (Init) return Init;
     if (Set) return Set;
     if (Modify) return Modify;
     if (MutableAddress) return MutableAddress;

lib/SIL/IR/SILFunctionType.cpp

@@ -2381,22 +2381,27 @@ static CanSILFunctionType getSILFunctionTypeForInitAccessor(
   // Drop `self` parameter.
   inputs.pop_back();
 
+  auto getLoweredTypeOfProperty = [&](VarDecl *property) {
+    auto type = property->getInterfaceType();
+    AbstractionPattern pattern(genericSig, type->getCanonicalType());
+    auto loweredTy = TC.getLoweredType(pattern, type, context);
+    return loweredTy.getASTType();
+  };
+
   // accessed properties appear as `inout` parameters because they could be
   // read from and modified.
   for (auto *property : accessor->getAccessedProperties()) {
-    inputs.push_back(
-        SILParameterInfo(property->getInterfaceType()->getCanonicalType(),
-                         ParameterConvention::Indirect_Inout));
+    inputs.push_back(SILParameterInfo(getLoweredTypeOfProperty(property),
+                                      ParameterConvention::Indirect_Inout));
   }
 
   SmallVector<SILResultInfo, 8> results;
 
   // initialized properties appear as `@out` results because they are
   // initialized by the accessor.
   for (auto *property : accessor->getInitializedProperties()) {
-    results.push_back(
-        SILResultInfo(property->getInterfaceType()->getCanonicalType(),
-                      ResultConvention::Indirect));
+    results.push_back(SILResultInfo(getLoweredTypeOfProperty(property),
+                                    ResultConvention::Indirect));
   }
 
   auto calleeConvention = ParameterConvention::Direct_Unowned;

lib/SILGen/SILGenConstructor.cpp

@@ -1584,8 +1584,8 @@ void SILGenFunction::emitInitAccessor(AccessorDecl *accessor) {
                             bool markUninitialized = false) {
     auto *arg = ParamDecl::createImplicit(
         getASTContext(), property->getBaseIdentifier(),
-        property->getBaseIdentifier(), type.getASTType()->mapTypeOutOfContext(),
-        accessor, ParamSpecifier::InOut);
+        property->getBaseIdentifier(), property->getInterfaceType(), accessor,
+        ParamSpecifier::InOut);
 
     RegularLocation loc(property);
     loc.markAutoGenerated();

lib/Serialization/Serialization.cpp

@@ -2954,7 +2954,7 @@ class Serializer::DeclSerializer : public DeclVisitor<DeclSerializer> {
     }
 
     case DAK_StorageRestrictions: {
-      auto abbrCode = S.DeclTypeAbbrCodes[AccessesDeclAttrLayout::Code];
+      auto abbrCode = S.DeclTypeAbbrCodes[StorageRestrictionsDeclAttrLayout::Code];
       auto attr = cast<StorageRestrictionsAttr>(DA);
 
       SmallVector<IdentifierID, 4> properties;

test/SILOptimizer/init_accessors.swift

@@ -395,6 +395,30 @@ func test_local_with_memberwise() {
   _ = TestMemberwiseGeneric(a: 1, pair: ("a", [0]))
 }
 
+// CHECK-LABEL: sil private [ossa] @$s14init_accessors023test_type_lowering_for_A9_accessoryyF4TestL_V2fnADyxq_Gq_xc_tcfC : $@convention(method) <T, U> (@owned @callee_guaranteed @substituted <τ_0_0, τ_0_1> (@in_guaranteed τ_0_0) -> @out τ_0_1 for <T, U>, @thin Test<T, U>.Type) -> @owned Test<T, U>
+// CHECK: {{.*}} = function_ref @$s14init_accessors023test_type_lowering_for_A9_accessoryyF4TestL_V2fnyq_xcvi : $@convention(thin) <τ_0_0, τ_0_1> (@owned @callee_guaranteed @substituted <τ_0_0, τ_0_1> (@in_guaranteed τ_0_0) -> @out τ_0_1 for <τ_0_0, τ_0_1>) -> @out Optional<@callee_guaranteed @substituted <τ_0_0, τ_0_1> (@in_guaranteed τ_0_0) -> @out τ_0_1 for <τ_0_0, τ_0_1>>
+func test_type_lowering_for_init_accessor() {
+  struct Test<T, U> {
+    var _fn: ((T) -> U)? = nil
+
+    // CHECK-LABEL: sil private [ossa] @$s14init_accessors023test_type_lowering_for_A9_accessoryyF4TestL_V2fnyq_xcvi : $@convention(thin) <T, U> (@owned @callee_guaranteed @substituted <τ_0_0, τ_0_1> (@in_guaranteed τ_0_0) -> @out τ_0_1 for <T, U>) -> @out Optional<@callee_guaranteed @substituted <τ_0_0, τ_0_1> (@in_guaranteed τ_0_0) -> @out τ_0_1 for <T, U>>
+    var fn: (T) -> U {
+      @storageRestrictions(initializes: _fn)
+      init { _fn = newValue }
+      get { _fn! }
+      set { _fn = newValue }
+    }
+
+    init(fn: @escaping (T) -> U) {
+      self.fn = fn
+    }
+  }
+
+  _ = Test<Int, () -> Void> { _ in
+    return {}
+  } // Ok
+}
+
 func test_assignments() {
   struct Test {
     var _a: Int

test/Serialization/init_accessors.swift

@@ -0,0 +1,66 @@
+// RUN: %empty-directory(%t)
+// RUN: %empty-directory(%t/src)
+// RUN: %empty-directory(%t/sdk)
+// RUN: split-file %s %t/src
+
+// REQUIRES: asserts
+
+// RUN: %target-swift-frontend -emit-module %t/src/PublicModule.swift \
+// RUN:   -module-name PublicModule -swift-version 5 \
+// RUN:   -emit-module-path %t/sdk/PublicModule.swiftmodule \
+// RUN:   -enable-experimental-feature InitAccessors
+
+// RUN: %target-swift-frontend -typecheck %t/src/Client.swift \
+// RUN:   -enable-experimental-feature InitAccessors \
+// RUN:   -module-name Client -I %t/sdk
+
+//--- PublicModule.swift
+public struct Test<T> {
+  private var _x: T
+
+  public var x: T {
+    @storageRestrictions(initializes: _x)
+    init {
+      _x = newValue
+    }
+
+    get { _x }
+    set { _x = newValue }
+  }
+
+  public init(data: T) {
+    self.x = data
+  }
+}
+
+public struct TestMulti<T, U> {
+  private var _a: T
+  private var _c: U
+
+  public var b: Int
+
+  public var data: (T, U) {
+    @storageRestrictions(initializes: _a, _c, accesses: b)
+    init {
+      _a = newValue.0
+      _c = newValue.1
+      b = 0
+    }
+
+    get { (_a, _c) }
+  }
+
+  public init(data: (T, U), b: Int) {
+    self.b = b
+    self.data = data
+  }
+}
+
+//--- Client.swift
+import PublicModule
+
+let test1 = Test<[Int]>(data: [1, 2, 3])
+_ = test1.x
+
+let test2 = TestMulti(data: ("Question", 42), b: -1)
+_ = print("\(test2.data), \(test2.b)")

test/decl/var/init_accessors.swift

@@ -86,12 +86,16 @@ func test_invalid_refs_in_init_attrs() {
       // expected-error@-2 {{find type 'b' in scope}}
       // expected-error@-3 {{init accessor cannot refer to property 'c'; init accessors can refer only to stored properties}}
       init(initialValue) {}
+
+      get { 0 }
     }
 
     var y: String {
       @storageRestrictions(initializes: test)
       // expected-error@-1 {{ambiguous reference to member 'test'}}
       init(initialValue) {}
+
+      get { "" }
     }
 
     func test(_: Int) {} // expected-note {{'test' declared here}}
@@ -110,6 +114,8 @@ func test_assignment_to_let_properties() {
         self.x = initialValue // Ok
         self.y = 42 // expected-error {{cannot assign to property: 'y' is a 'let' constant}}
       }
+
+      get { x }
     }
 
     var point: (Int, Int) {
@@ -157,6 +163,8 @@ func test_duplicate_and_computed_lazy_properties() {
       // expected-error@-2 {{init accessor cannot refer to property 'b'; init accessors can refer only to stored properties}}
       // expected-error@-3 {{init accessor cannot refer to property 'c'; init accessors can refer only to stored properties}}
       init(initialValue) {}
+
+      get { _a }
     }
 
     var b: Int {
@@ -475,11 +483,15 @@ func test_default_arguments_are_analyzed() {
   struct Test {
     var pair: (Int, Int) = (0, 1) { // Ok
       init {}
+
+      get { (0, 1) }
     }
 
     var other: (Int, String) = ("", 42) {
       // expected-error@-1 {{cannot convert value of type '(String, Int)' to specified type '(Int, String)'}}
       init(initialValue) {}
+
+      get { (0, "") }
     }
 
     var otherPair = (0, 1) {
@@ -558,36 +570,47 @@ func test_invalid_storage_restrictions() {
       @storageRestrictions()
       // expected-error@-1 {{missing label in @storageRestrictions attribute}}
       init {}
+
+      get { _a }
     }
 
     var b: Int {
       @storageRestrictions(initializes:)
       // expected-error@-1 {{expected property name in @storageRestrictions list}}
       init {}
+
+      get { _b }
     }
 
     var c: Int {
       @storageRestrictions(initializes: a, initializes: b)
       // expected-error@-1 {{duplicate label 'initializes' in @storageRestrictions attribute}}
       init {}
+
+      get { 0 }
     }
 
     var d: Int {
       @storageRestrictions(accesses: a, accesses: c)
       // expected-error@-1 {{duplicate label 'accesses' in @storageRestrictions attribute}}
       init {}
+
+      get { 0 }
     }
 
     var e: Int {
       @storageRestrictions(initialize: a, b, accesses: c, d)
       // expected-error@-1 {{unexpected label 'initialize' in @storageRestrictions attribute}}
       init {}
+
+      get { 0 }
     }
 
     var f: Int {
       @storageRestrictions(initializes: _a, accesses: _b, _a)
       // expected-error@-1 {{property '_a' cannot be both initialized and accessed}}
       init {}
+      // expected-error@-1 {{variable with an init accessor must also have a getter}}
     }
 
     var g: Int {