[AST] Associated isActorSelf with VarDecl

Author: xedin

include/swift/AST/Decl.h

@@ -5300,6 +5300,9 @@ class VarDecl : public AbstractStorageDecl {
   /// Returns true if the name is the self identifier and is implicit.
   bool isSelfParameter() const;
 
+  /// Check whether the variable is the "self" of an actor method.
+  bool isActorSelf() const;
+
   /// Determine whether this property will be part of the implicit memberwise
   /// initializer.
   ///

lib/AST/Decl.cpp

@@ -6042,6 +6042,20 @@ bool VarDecl::isSelfParameter() const {
   return false;
 }
 
+bool VarDecl::isActorSelf() const {
+  if (!isSelfParameter() && !isSelfParamCapture())
+    return false;
+
+  auto *dc = getDeclContext();
+  while (!dc->isTypeContext() && !dc->isModuleScopeContext())
+    dc = dc->getParent();
+
+  // Check if this `self` parameter belogs to an actor declaration or
+  // extension.
+  auto nominal = dc->getSelfNominalTypeDecl();
+  return nominal && nominal->isActor();
+}
+
 /// Whether the given variable is the backing storage property for
 /// a declared property that is either `lazy` or has an attached
 /// property wrapper.