Sema: Fix materializeForSet overrides

lib/Sema/CodeSynthesis.cpp

@@ -814,6 +814,20 @@ static FuncDecl *addMaterializeForSet(AbstractStorageDecl *storage,
                              storage->getSetter());
   storage->setMaterializeForSetFunc(materializeForSet);
 
+  // Make sure we record the override.
+  //
+  // FIXME: Instead, we should just not call checkOverrides() on
+  // storage until all accessors are in place.
+  if (auto *baseASD = storage->getOverriddenDecl()) {
+    // If the base storage has a private setter, we're not overriding
+    // materializeForSet either.
+    auto *baseMFS = baseASD->getMaterializeForSetFunc();
+    if (baseMFS != nullptr &&
+        baseASD->isSetterAccessibleFrom(storage->getDeclContext())) {
+      materializeForSet->setOverriddenDecl(baseMFS);
+    }
+  }
+
   return materializeForSet;
 }
 

test/Interpreter/classes.swift

@@ -207,3 +207,29 @@ func makeOne<T : Makeable>(_: T.Type) -> T {
 }
 
 makeOne(Child.self).doSomething() // CHECK: Heaven!
+
+// https://bugs.swift.org/browse/SR-3840
+
+class BaseProperty {
+  var value: Int {
+    get { fatalError() }
+    set { fatalError() }
+  }
+
+  func increment() -> Self {
+    value += 1
+    return self
+  }
+}
+
+class DerivedProperty : BaseProperty {
+  override var value: Int {
+    get { return _value }
+    set { _value = newValue }
+  }
+
+  var _value: Int = 0
+}
+
+// CHECK: 1
+print(DerivedProperty().increment().value)

test/SILGen/materializeForSet.swift

@@ -385,6 +385,21 @@ func inoutAccessOfStaticProperty<T : Beverage>(_ t: T.Type) {
   increment(&t.abv)
 }
 
+// Test for materializeForSet vs overriden computed property of classes.
+class BaseForOverride {
+  var valueStored: Int
+  var valueComputed: Int { get { } set { } }
+
+  init(valueStored: Int) {
+    self.valueStored = valueStored
+  }
+}
+
+class DerivedForOverride : BaseForOverride {
+  override var valueStored: Int { get { } set { } }
+  override var valueComputed: Int { get { } set { } }
+}
+
 // Test for materializeForSet vs static properties of classes.
 
 class ReferenceBeer {
@@ -514,6 +529,15 @@ func testMaterializedSetter() {
   f.computed = f.computed
 }
 
+// CHECK-LABEL: sil_vtable DerivedForOverride {
+// CHECK:   #BaseForOverride.valueComputed!getter.1: (BaseForOverride) -> () -> Int : _T017materializeForSet07DerivedB8OverrideC13valueComputedSifg
+// CHECK:   #BaseForOverride.valueComputed!setter.1: (BaseForOverride) -> (Int) -> () : _T017materializeForSet07DerivedB8OverrideC13valueComputedSifs
+// CHECK:   #BaseForOverride.valueComputed!materializeForSet.1: (BaseForOverride) -> (Builtin.RawPointer, inout Builtin.UnsafeValueBuffer) -> (Builtin.RawPointer, Builtin.RawPointer?) : _T017materializeForSet07DerivedB8OverrideC13valueComputedSifm
+// CHECK:   #BaseForOverride.valueStored!getter.1: (BaseForOverride) -> () -> Int : _T017materializeForSet07DerivedB8OverrideC11valueStoredSifg
+// CHECK:   #BaseForOverride.valueStored!setter.1: (BaseForOverride) -> (Int) -> () : _T017materializeForSet07DerivedB8OverrideC11valueStoredSifs
+// CHECK:   #BaseForOverride.valueStored!materializeForSet.1: (BaseForOverride) -> (Builtin.RawPointer, inout Builtin.UnsafeValueBuffer) -> (Builtin.RawPointer, Builtin.RawPointer?) : _T017materializeForSet07DerivedB8OverrideC11valueStoredSifm
+// CHECK: }
+
 // CHECK-LABEL: sil_witness_table hidden Bill: Totalled module materializeForSet {
 // CHECK:   method #Totalled.total!getter.1: {{.*}} : @_T017materializeForSet4BillVAA8TotalledAaaDP5totalSifgTW
 // CHECK:   method #Totalled.total!setter.1: {{.*}} : @_T017materializeForSet4BillVAA8TotalledAaaDP5totalSifsTW