[Typechecker] Fix _modify for properties using a property wrapper

Author: theblixguy

lib/Sema/TypeCheckStorage.cpp

@@ -743,8 +743,6 @@ static Expr *buildStorageReference(AccessorDecl *accessor,
   bool isMemberLValue = isLValue;
   auto propertyWrapperMutability =
       [&](Decl *decl) -> Optional<std::pair<bool, bool>> {
-    if (accessor->isCoroutine())
-      return None;
     auto var = dyn_cast<VarDecl>(decl);
     if (!var)
       return None;
@@ -1572,6 +1570,13 @@ synthesizeCoroutineAccessorBody(AccessorDecl *accessor, ASTContext &ctx) {
                    ? TargetImpl::Ordinary
                    : TargetImpl::Implementation);
 
+  // If this is a variable with an attached property wrapper, then
+  // the accessors need to yield the wrapped value.
+  if (isa<VarDecl>(storage) &&
+      cast<VarDecl>(storage)->hasAttachedPropertyWrapper()) {
+    target = TargetImpl::Wrapper;
+  }
+
   SourceLoc loc = storage->getLoc();
   SmallVector<ASTNode, 1> body;
 
@@ -1602,8 +1607,11 @@ synthesizeReadCoroutineBody(AccessorDecl *read, ASTContext &ctx) {
 static std::pair<BraceStmt *, bool>
 synthesizeModifyCoroutineBody(AccessorDecl *modify, ASTContext &ctx) {
 #ifndef NDEBUG
-  auto impl = modify->getStorage()->getReadWriteImpl();
-  assert(impl != ReadWriteImplKind::Modify &&
+  auto storage = modify->getStorage();
+  auto impl = storage->getReadWriteImpl();
+  auto hasWrapper = isa<VarDecl>(storage) &&
+                    cast<VarDecl>(storage)->hasAttachedPropertyWrapper();
+  assert((hasWrapper || impl != ReadWriteImplKind::Modify) &&
          impl != ReadWriteImplKind::Immutable);
 #endif
   return synthesizeCoroutineAccessorBody(modify, ctx);
@@ -2548,7 +2556,8 @@ static void finishPropertyWrapperImplInfo(VarDecl *var,
   }
 
   if (wrapperSetterIsUsable)
-    info = StorageImplInfo::getMutableComputed();
+    info = StorageImplInfo(ReadImplKind::Get, WriteImplKind::Set,
+                           ReadWriteImplKind::Modify);
   else
     info = StorageImplInfo::getImmutableComputed();
 }

test/SILGen/property_wrapper_coroutine.swift

@@ -0,0 +1,41 @@
+// RUN: %target-swift-emit-silgen %s | %FileCheck %s
+
+@propertyWrapper
+struct TestWrapper<ValueType> {
+  var wrappedValue: ValueType
+}
+
+struct State {
+  @TestWrapper var values: [String] = []
+}
+
+var state = State()
+state.values = Array(repeating: "", count: 20000)
+
+for i in 0..<20000 {
+  // CHECK: bb3([[INDEX:%.*]] : $Int):
+  // CHECK:  [[BEGIN_ACCESS_MODIFY:%.*]] = begin_access [modify] [dynamic] {{%.*}} : $*State
+  // CHECK:  [[REF_MODIFY:%.*]] = function_ref @$s26property_wrapper_coroutine5StateV6valuesSaySSGvM : $@yield_once @convention(method) (@inout State) -> @yields @inout Array<String>
+  // CHECK:  ([[RES1:%.*]], {{%.*}}) = begin_apply [[REF_MODIFY]]([[BEGIN_ACCESS_MODIFY]]) : $@yield_once @convention(method) (@inout State) -> @yields @inout Array<String>
+  // CHECK:  [[REF_ARRAY_SUBSCRIPT:%.*]] = function_ref @$sSayxSiciM : $@yield_once @convention(method) <τ_0_0> (Int, @inout Array<τ_0_0>) -> @yields @inout τ_0_0
+  // CHECK:  ({{%.*}}, {{%.*}}) = begin_apply [[REF_ARRAY_SUBSCRIPT]]<String>([[INDEX]], [[RES1]]) : $@yield_once @convention(method) <τ_0_0> (Int, @inout Array<τ_0_0>) -> @yields @inout τ_0_0
+  state.values[i] = String(i)
+}
+
+// CHECK-LABEL: sil hidden [transparent] [ossa] @$s26property_wrapper_coroutine5StateV6valuesSaySSGvM : $@yield_once @convention(method) (@inout State) -> @yields @inout Array<String> {
+// CHECK: bb0([[STATE:%.*]] : $*State):
+// CHECK:  debug_value_addr [[STATE]] : $*State, var, name "self", argno {{.*}}
+// CHECK:  [[BEGIN_ACCESS:%.*]] = begin_access [modify] [unknown] [[STATE]] : $*State
+// CHECK:  [[BACKING_ADDR:%.*]] = struct_element_addr [[BEGIN_ACCESS]] : $*State, #State._values
+// CHECK:  [[VALUE_ADDR:%.*]] = struct_element_addr [[BACKING_ADDR]] : $*TestWrapper<Array<String>>, #TestWrapper.wrappedValue
+// CHECK:  yield [[VALUE_ADDR]] : $*Array<String>, resume bb1, unwind bb2
+//
+// CHECK: bb1:
+// CHECK:  end_access [[BEGIN_ACCESS]] : $*State
+// CHECK:  [[RETURN:%.*]] = tuple ()
+// CHECK:  return [[RETURN]] : $()
+//
+// CHECK: bb2:
+// CHECK:  end_access [[BEGIN_ACCESS]] : $*State
+// CHECK:  unwind
+// CHECK-END: }