[Property Wrappers] For now, don't allow wrappedValue and projectedValue

to have dynamic Self type.

Author: hborla

include/swift/AST/DiagnosticsSema.def

@@ -4904,6 +4904,9 @@ ERROR(property_wrapper_type_requirement_not_accessible,none,
 ERROR(property_wrapper_ambiguous_enclosing_self_subscript, none,
       "property wrapper type %0 has multiple enclosing-self subscripts %1",
       (Type, DeclName))
+ERROR(property_wrapper_dynamic_self_type, none,
+      "property wrapper %select{wrapped value|projected value}0 cannot have "
+      "dynamic Self type", (bool))
 
 ERROR(property_wrapper_attribute_not_on_property, none,
       "property wrapper attribute %0 can only be applied to a property",

lib/Sema/TypeCheckAttr.cpp

@@ -2862,7 +2862,7 @@ void AttributeChecker::visitCustomAttr(CustomAttr *attr) {
 
   // If the nominal type is a property wrapper type, we can be delegating
   // through a property.
-  if (nominal->getPropertyWrapperTypeInfo()) {
+  if (nominal->getAttrs().hasAttribute<PropertyWrapperAttr>()) {
     // property wrappers can only be applied to variables
     if (!isa<VarDecl>(D) || isa<ParamDecl>(D)) {
       diagnose(attr->getLocation(),

lib/Sema/TypeCheckPropertyWrapper.cpp

@@ -406,6 +406,27 @@ PropertyWrapperTypeInfoRequest::evaluate(
     }
   }
 
+  auto diagnoseInvalidDynamicSelf = [&]() -> bool {
+    bool invalidDynamicSelf = false;
+    if (result.projectedValueVar &&
+        result.projectedValueVar->getValueInterfaceType()->is<DynamicSelfType>()) {
+      result.projectedValueVar->diagnose(
+          diag::property_wrapper_dynamic_self_type, /*projectedValue=*/true);
+      invalidDynamicSelf = true;
+    }
+
+    if (result.valueVar->getValueInterfaceType()->is<DynamicSelfType>()) {
+      result.valueVar->diagnose(
+          diag::property_wrapper_dynamic_self_type, /*projectedValue=*/false);
+      invalidDynamicSelf = true;
+    }
+
+    return invalidDynamicSelf;
+  };
+
+  if (diagnoseInvalidDynamicSelf())
+    return PropertyWrapperTypeInfo();
+
   return result;
 }
 

test/decl/var/property_wrappers.swift

@@ -818,13 +818,28 @@ struct TestProjectionValuePropertyAttr {
 @propertyWrapper
 struct BrokenLazy { }
 // expected-error@-1{{property wrapper type 'BrokenLazy' does not contain a non-static property named 'wrappedValue'}}
-// expected-note@-2{{'BrokenLazy' declared here}}
 
 struct S {
-  @BrokenLazy // expected-error{{struct 'BrokenLazy' cannot be used as an attribute}}
+  @BrokenLazy
   var wrappedValue: Int
 }
 
+@propertyWrapper
+struct DynamicSelfStruct {
+  var wrappedValue: Self { self } // okay
+  var projectedValue: Self { self } // okay
+}
+
+@propertyWrapper
+class DynamicSelf {
+  var wrappedValue: Self { self } // expected-error {{property wrapper wrapped value cannot have dynamic Self type}}
+  var projectedValue: Self { self } // expected-error {{property wrapper projected value cannot have dynamic Self type}}
+}
+
+struct UseDynamicSelfWrapper {
+  @DynamicSelf() var value
+}
+
 // ---------------------------------------------------------------------------
 // Invalid redeclaration
 // ---------------------------------------------------------------------------