[Property Wrappers] For a property with an attached property wrapper,

consider its didSet mutability when computing setter mutability.

Author: hborla

lib/Sema/TypeCheckStorage.cpp

@@ -342,10 +342,13 @@ IsSetterMutatingRequest::evaluate(Evaluator &evaluator,
   if (auto var = dyn_cast<VarDecl>(storage)) {
     if (auto mut = var->getPropertyWrapperMutability()) {
       bool isMutating = mut->Setter == PropertyWrapperMutability::Mutating;
-      if (var->getParsedAccessor(AccessorKind::DidSet)) {
+      if (auto *accessor = var->getParsedAccessor(AccessorKind::DidSet)) {
         // If there's a didSet, we call the getter for the 'oldValue', and so
         // should consider the getter's mutatingness as well
-        isMutating |= (mut->Getter == PropertyWrapperMutability::Mutating);
+        if (!accessor->isSimpleDidSet()) {
+          isMutating |= (mut->Getter == PropertyWrapperMutability::Mutating);
+        }
+        isMutating |= accessor->getAttrs().hasAttribute<MutatingAttr>();
       }
       return isMutating && result;
     }

test/SILGen/property_wrapper_observers.swift

@@ -68,4 +68,28 @@ class Bar {
 // CHECK-NEXT:  destroy_addr [[ALLOC_STACK]] : $*Array<Int>
 // CHECK-NEXT:  dealloc_stack [[ALLOC_STACK]] : $*Array<Int>
 // CHECK-NEXT:  unwind
-// CHECK-END: }
+// CHECK-END: }
+
+
+@propertyWrapper
+struct State {
+  var wrappedValue: Int {
+    get { 0 }
+    nonmutating set {}
+  }
+}
+
+struct MutatingDidSet {
+  @State private var value: Int {
+    mutating didSet {}
+  }
+
+  mutating func test() {
+    value = 10
+  }
+}
+
+// MutatingDidSet.value.setter
+// CHECK-LABEL: sil private [ossa] @$s26property_wrapper_observers14MutatingDidSetV5value33_{{.*}} : $@convention(method) (Int, @inout MutatingDidSet) -> () {
+// CHECK: function_ref @$s26property_wrapper_observers5StateV12wrappedValueSivs : $@convention(method) (Int, State) -> ()
+// CHECK: function_ref @$s26property_wrapper_observers14MutatingDidSetV5value33_{{.*}} : $@convention(method) (@inout MutatingDidSet) -> ()