Derive all ast::Node from Castable

The hand-rolled `AsBlah()`, `IsBlah()` methods will be migrated in future changes.

Change-Id: I078c100b561b50018771cc38c1cac4379c393424
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/34301
Reviewed-by: dan sinclair <dsinclair@chromium.org>

src/ast/access_decoration.cc

@@ -20,7 +20,7 @@ namespace ast {
 constexpr const DecorationKind AccessDecoration::Kind;
 
 AccessDecoration::AccessDecoration(AccessControl val, const Source& source)
-    : TypeDecoration(source), value_(val) {}
+    : Base(source), value_(val) {}
 
 AccessDecoration::~AccessDecoration() = default;
 
@@ -29,7 +29,7 @@ DecorationKind AccessDecoration::GetKind() const {
 }
 
 bool AccessDecoration::IsKind(DecorationKind kind) const {
-  return kind == Kind || TypeDecoration::IsKind(kind);
+  return kind == Kind || Base::IsKind(kind);
 }
 
 bool AccessDecoration::IsAccess() const {

src/ast/access_decoration.h

@@ -24,7 +24,7 @@ namespace tint {
 namespace ast {
 
 /// An access decoration
-class AccessDecoration : public TypeDecoration {
+class AccessDecoration : public Castable<AccessDecoration, TypeDecoration> {
  public:
   /// The kind of decoration that this type represents
   static constexpr const DecorationKind Kind = DecorationKind::kAccess;

src/ast/array_accessor_expression.cc

@@ -17,16 +17,16 @@
 namespace tint {
 namespace ast {
 
-ArrayAccessorExpression::ArrayAccessorExpression() : Expression() {}
+ArrayAccessorExpression::ArrayAccessorExpression() : Base() {}
 
 ArrayAccessorExpression::ArrayAccessorExpression(Expression* array,
                                                  Expression* idx_expr)
-    : Expression(), array_(array), idx_expr_(idx_expr) {}
+    : Base(), array_(array), idx_expr_(idx_expr) {}
 
 ArrayAccessorExpression::ArrayAccessorExpression(const Source& source,
                                                  Expression* array,
                                                  Expression* idx_expr)
-    : Expression(source), array_(array), idx_expr_(idx_expr) {}
+    : Base(source), array_(array), idx_expr_(idx_expr) {}
 
 ArrayAccessorExpression::ArrayAccessorExpression(ArrayAccessorExpression&&) =
     default;

src/ast/array_accessor_expression.h

@@ -25,7 +25,8 @@ namespace tint {
 namespace ast {
 
 /// An array accessor expression
-class ArrayAccessorExpression : public Expression {
+class ArrayAccessorExpression
+    : public Castable<ArrayAccessorExpression, Expression> {
  public:
   /// Constructor
   ArrayAccessorExpression();

src/ast/array_decoration.cc

@@ -23,7 +23,7 @@ namespace ast {
 
 constexpr const DecorationKind ArrayDecoration::Kind;
 
-ArrayDecoration::ArrayDecoration(const Source& source) : Decoration(source) {}
+ArrayDecoration::ArrayDecoration(const Source& source) : Base(source) {}
 
 ArrayDecoration::~ArrayDecoration() = default;
 

src/ast/array_decoration.h

@@ -27,7 +27,7 @@ namespace ast {
 class StrideDecoration;
 
 /// A decoration attached to an array
-class ArrayDecoration : public Decoration {
+class ArrayDecoration : public Castable<ArrayDecoration, Decoration> {
  public:
   /// The kind of decoration that this type represents
   static constexpr const DecorationKind Kind = DecorationKind::kArray;

src/ast/assignment_statement.cc

@@ -17,15 +17,15 @@
 namespace tint {
 namespace ast {
 
-AssignmentStatement::AssignmentStatement() : Statement() {}
+AssignmentStatement::AssignmentStatement() : Base() {}
 
 AssignmentStatement::AssignmentStatement(Expression* lhs, Expression* rhs)
-    : Statement(), lhs_(lhs), rhs_(rhs) {}
+    : Base(), lhs_(lhs), rhs_(rhs) {}
 
 AssignmentStatement::AssignmentStatement(const Source& source,
                                          Expression* lhs,
                                          Expression* rhs)
-    : Statement(source), lhs_(lhs), rhs_(rhs) {}
+    : Base(source), lhs_(lhs), rhs_(rhs) {}
 
 AssignmentStatement::AssignmentStatement(AssignmentStatement&&) = default;
 

src/ast/assignment_statement.h

@@ -26,7 +26,7 @@ namespace tint {
 namespace ast {
 
 /// An assignment statement
-class AssignmentStatement : public Statement {
+class AssignmentStatement : public Castable<AssignmentStatement, Statement> {
  public:
   /// Constructor
   AssignmentStatement();

src/ast/binary_expression.cc

@@ -17,18 +17,18 @@
 namespace tint {
 namespace ast {
 
-BinaryExpression::BinaryExpression() : Expression() {}
+BinaryExpression::BinaryExpression() : Base() {}
 
 BinaryExpression::BinaryExpression(BinaryOp op,
                                    Expression* lhs,
                                    Expression* rhs)
-    : Expression(), op_(op), lhs_(lhs), rhs_(rhs) {}
+    : Base(), op_(op), lhs_(lhs), rhs_(rhs) {}
 
 BinaryExpression::BinaryExpression(const Source& source,
                                    BinaryOp op,
                                    Expression* lhs,
                                    Expression* rhs)
-    : Expression(source), op_(op), lhs_(lhs), rhs_(rhs) {}
+    : Base(source), op_(op), lhs_(lhs), rhs_(rhs) {}
 
 BinaryExpression::BinaryExpression(BinaryExpression&&) = default;
 

src/ast/binary_expression.h

@@ -48,7 +48,7 @@ enum class BinaryOp {
 };
 
 /// An binary expression
-class BinaryExpression : public Expression {
+class BinaryExpression : public Castable<BinaryExpression, Expression> {
  public:
   /// Constructor
   BinaryExpression();

src/ast/binding_decoration.cc

@@ -20,7 +20,7 @@ namespace ast {
 constexpr const DecorationKind BindingDecoration::Kind;
 
 BindingDecoration::BindingDecoration(uint32_t val, const Source& source)
-    : VariableDecoration(source), value_(val) {}
+    : Base(source), value_(val) {}
 
 BindingDecoration::~BindingDecoration() = default;
 
@@ -29,7 +29,7 @@ DecorationKind BindingDecoration::GetKind() const {
 }
 
 bool BindingDecoration::IsKind(DecorationKind kind) const {
-  return kind == Kind || VariableDecoration::IsKind(kind);
+  return kind == Kind || Base::IsKind(kind);
 }
 
 bool BindingDecoration::IsBinding() const {

src/ast/binding_decoration.h

@@ -23,7 +23,8 @@ namespace tint {
 namespace ast {
 
 /// A binding decoration
-class BindingDecoration : public VariableDecoration {
+class BindingDecoration
+    : public Castable<BindingDecoration, VariableDecoration> {
  public:
   /// The kind of decoration that this type represents
   static constexpr const DecorationKind Kind = DecorationKind::kBinding;

src/ast/bitcast_expression.cc

@@ -17,15 +17,15 @@
 namespace tint {
 namespace ast {
 
-BitcastExpression::BitcastExpression() : Expression() {}
+BitcastExpression::BitcastExpression() : Base() {}
 
 BitcastExpression::BitcastExpression(type::Type* type, Expression* expr)
-    : Expression(), type_(type), expr_(expr) {}
+    : Base(), type_(type), expr_(expr) {}
 
 BitcastExpression::BitcastExpression(const Source& source,
                                      type::Type* type,
                                      Expression* expr)
-    : Expression(source), type_(type), expr_(expr) {}
+    : Base(source), type_(type), expr_(expr) {}
 
 BitcastExpression::BitcastExpression(BitcastExpression&&) = default;
 BitcastExpression::~BitcastExpression() = default;

src/ast/bitcast_expression.h

@@ -26,7 +26,7 @@ namespace tint {
 namespace ast {
 
 /// A bitcast expression
-class BitcastExpression : public Expression {
+class BitcastExpression : public Castable<BitcastExpression, Expression> {
  public:
   /// Constructor
   BitcastExpression();

src/ast/block_statement.cc

@@ -17,9 +17,9 @@
 namespace tint {
 namespace ast {
 
-BlockStatement::BlockStatement() : Statement() {}
+BlockStatement::BlockStatement() : Base() {}
 
-BlockStatement::BlockStatement(const Source& source) : Statement(source) {}
+BlockStatement::BlockStatement(const Source& source) : Base(source) {}
 
 BlockStatement::BlockStatement(BlockStatement&&) = default;
 

src/ast/block_statement.h

@@ -25,7 +25,7 @@ namespace tint {
 namespace ast {
 
 /// A block statement
-class BlockStatement : public Statement {
+class BlockStatement : public Castable<BlockStatement, Statement> {
  public:
   /// Constructor
   BlockStatement();

src/ast/bool_literal.cc

@@ -18,7 +18,7 @@ namespace tint {
 namespace ast {
 
 BoolLiteral::BoolLiteral(ast::type::Type* type, bool value)
-    : Literal(type), value_(value) {}
+    : Base(type), value_(value) {}
 
 BoolLiteral::~BoolLiteral() = default;
 

src/ast/bool_literal.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace ast {
 
 /// A boolean literal
-class BoolLiteral : public Literal {
+class BoolLiteral : public Castable<BoolLiteral, Literal> {
  public:
   /// Constructor
   /// @param type the type of the literal

src/ast/break_statement.cc

@@ -17,9 +17,9 @@
 namespace tint {
 namespace ast {
 
-BreakStatement::BreakStatement() : Statement() {}
+BreakStatement::BreakStatement() : Base() {}
 
-BreakStatement::BreakStatement(const Source& source) : Statement(source) {}
+BreakStatement::BreakStatement(const Source& source) : Base(source) {}
 
 BreakStatement::BreakStatement(BreakStatement&&) = default;
 

src/ast/break_statement.h

@@ -21,7 +21,7 @@ namespace tint {
 namespace ast {
 
 /// An break statement
-class BreakStatement : public Statement {
+class BreakStatement : public Castable<BreakStatement, Statement> {
  public:
   /// Constructor
   BreakStatement();

src/ast/builtin_decoration.cc

@@ -20,7 +20,7 @@ namespace ast {
 constexpr const DecorationKind BuiltinDecoration::Kind;
 
 BuiltinDecoration::BuiltinDecoration(Builtin builtin, const Source& source)
-    : VariableDecoration(source), builtin_(builtin) {}
+    : Base(source), builtin_(builtin) {}
 
 BuiltinDecoration::~BuiltinDecoration() = default;
 
@@ -29,7 +29,7 @@ DecorationKind BuiltinDecoration::GetKind() const {
 }
 
 bool BuiltinDecoration::IsKind(DecorationKind kind) const {
-  return kind == Kind || VariableDecoration::IsKind(kind);
+  return kind == Kind || Base::IsKind(kind);
 }
 
 bool BuiltinDecoration::IsBuiltin() const {

src/ast/builtin_decoration.h

@@ -22,7 +22,8 @@ namespace tint {
 namespace ast {
 
 /// A builtin decoration
-class BuiltinDecoration : public VariableDecoration {
+class BuiltinDecoration
+    : public Castable<BuiltinDecoration, VariableDecoration> {
  public:
   /// The kind of decoration that this type represents
   static constexpr const DecorationKind Kind = DecorationKind::kBuiltin;

src/ast/call_expression.cc

@@ -17,15 +17,15 @@
 namespace tint {
 namespace ast {
 
-CallExpression::CallExpression() : Expression() {}
+CallExpression::CallExpression() : Base() {}
 
 CallExpression::CallExpression(Expression* func, ExpressionList params)
-    : Expression(), func_(func), params_(params) {}
+    : Base(), func_(func), params_(params) {}
 
 CallExpression::CallExpression(const Source& source,
                                Expression* func,
                                ExpressionList params)
-    : Expression(source), func_(func), params_(params) {}
+    : Base(source), func_(func), params_(params) {}
 
 CallExpression::CallExpression(CallExpression&&) = default;
 

src/ast/call_expression.h

@@ -25,7 +25,7 @@ namespace tint {
 namespace ast {
 
 /// A call expression
-class CallExpression : public Expression {
+class CallExpression : public Castable<CallExpression, Expression> {
  public:
   /// Constructor
   CallExpression();

src/ast/call_statement.cc

@@ -19,9 +19,9 @@
 namespace tint {
 namespace ast {
 
-CallStatement::CallStatement() : Statement() {}
+CallStatement::CallStatement() : Base() {}
 
-CallStatement::CallStatement(CallExpression* call) : Statement(), call_(call) {}
+CallStatement::CallStatement(CallExpression* call) : Base(), call_(call) {}
 
 CallStatement::CallStatement(CallStatement&&) = default;
 

src/ast/call_statement.h

@@ -25,7 +25,7 @@ namespace tint {
 namespace ast {
 
 /// A call expression
-class CallStatement : public Statement {
+class CallStatement : public Castable<CallStatement, Statement> {
  public:
   /// Constructor
   CallStatement();

src/ast/case_statement.cc

@@ -17,15 +17,15 @@
 namespace tint {
 namespace ast {
 
-CaseStatement::CaseStatement(BlockStatement* body) : Statement(), body_(body) {}
+CaseStatement::CaseStatement(BlockStatement* body) : Base(), body_(body) {}
 
 CaseStatement::CaseStatement(CaseSelectorList selectors, BlockStatement* body)
-    : Statement(), selectors_(selectors), body_(body) {}
+    : Base(), selectors_(selectors), body_(body) {}
 
 CaseStatement::CaseStatement(const Source& source,
                              CaseSelectorList selectors,
                              BlockStatement* body)
-    : Statement(source), selectors_(selectors), body_(body) {}
+    : Base(source), selectors_(selectors), body_(body) {}
 
 CaseStatement::CaseStatement(CaseStatement&&) = default;
 

src/ast/case_statement.h

@@ -31,7 +31,7 @@ namespace ast {
 using CaseSelectorList = std::vector<IntLiteral*>;
 
 /// A case statement
-class CaseStatement : public Statement {
+class CaseStatement : public Castable<CaseStatement, Statement> {
  public:
   /// Constructor
   /// Creates a default case statement

src/ast/constant_id_decoration.cc

@@ -20,7 +20,7 @@ namespace ast {
 constexpr const DecorationKind ConstantIdDecoration::Kind;
 
 ConstantIdDecoration::ConstantIdDecoration(uint32_t val, const Source& source)
-    : VariableDecoration(source), value_(val) {}
+    : Base(source), value_(val) {}
 
 ConstantIdDecoration::~ConstantIdDecoration() = default;
 
@@ -29,7 +29,7 @@ DecorationKind ConstantIdDecoration::GetKind() const {
 }
 
 bool ConstantIdDecoration::IsKind(DecorationKind kind) const {
-  return kind == Kind || VariableDecoration::IsKind(kind);
+  return kind == Kind || Base::IsKind(kind);
 }
 
 bool ConstantIdDecoration::IsConstantId() const {

src/ast/constant_id_decoration.h

@@ -22,7 +22,8 @@ namespace tint {
 namespace ast {
 
 /// A constant id decoration
-class ConstantIdDecoration : public VariableDecoration {
+class ConstantIdDecoration
+    : public Castable<ConstantIdDecoration, VariableDecoration> {
  public:
   /// The kind of decoration that this type represents
   static constexpr const DecorationKind Kind = DecorationKind::kConstantId;

src/ast/constructor_expression.cc

@@ -26,8 +26,10 @@ ConstructorExpression::ConstructorExpression() = default;
 
 ConstructorExpression::~ConstructorExpression() = default;
 
+ConstructorExpression::ConstructorExpression(ConstructorExpression&&) = default;
+
 ConstructorExpression::ConstructorExpression(const Source& source)
-    : Expression(source) {}
+    : Base(source) {}
 
 bool ConstructorExpression::IsConstructor() const {
   return true;

src/ast/constructor_expression.h

@@ -24,7 +24,8 @@ class ScalarConstructorExpression;
 class TypeConstructorExpression;
 
 /// Base class for constructor style expressions
-class ConstructorExpression : public Expression {
+class ConstructorExpression
+    : public Castable<ConstructorExpression, Expression> {
  public:
   ~ConstructorExpression() override;
 
@@ -48,7 +49,7 @@ class ConstructorExpression : public Expression {
   /// @param source the constructor source
   explicit ConstructorExpression(const Source& source);
   /// Move constructor
-  ConstructorExpression(ConstructorExpression&&) = default;
+  ConstructorExpression(ConstructorExpression&&);
 
  private:
   ConstructorExpression(const ConstructorExpression&) = delete;

src/ast/continue_statement.cc

@@ -17,10 +17,9 @@
 namespace tint {
 namespace ast {
 
-ContinueStatement::ContinueStatement() : Statement() {}
+ContinueStatement::ContinueStatement() : Base() {}
 
-ContinueStatement::ContinueStatement(const Source& source)
+ContinueStatement::ContinueStatement(const Source& source) : Base(source) {}
-    : Statement(source) {}
 
 ContinueStatement::ContinueStatement(ContinueStatement&&) = default;
 

src/ast/continue_statement.h

@@ -24,7 +24,7 @@ namespace tint {
 namespace ast {
 
 /// An continue statement
-class ContinueStatement : public Statement {
+class ContinueStatement : public Castable<ContinueStatement, Statement> {
  public:
   /// Constructor
   ContinueStatement();

src/ast/decorated_variable.cc

@@ -24,7 +24,7 @@ namespace ast {
 DecoratedVariable::DecoratedVariable() = default;
 
 DecoratedVariable::DecoratedVariable(Variable* var)
-    : Variable(var->source(), var->name(), var->storage_class(), var->type()) {}
+    : Base(var->source(), var->name(), var->storage_class(), var->type()) {}
 
 DecoratedVariable::DecoratedVariable(DecoratedVariable&&) = default;
 

src/ast/decorated_variable.h

@@ -25,7 +25,7 @@ namespace tint {
 namespace ast {
 
 /// A Decorated Variable statement.
-class DecoratedVariable : public Variable {
+class DecoratedVariable : public Castable<DecoratedVariable, Variable> {
  public:
   /// Create a new empty decorated variable statement
   DecoratedVariable();

src/ast/decoration.h

@@ -47,7 +47,7 @@ enum class DecorationKind {
 std::ostream& operator<<(std::ostream& out, DecorationKind data);
 
 /// The base class for all decorations
-class Decoration : public Node {
+class Decoration : public Castable<Decoration, Node> {
  public:
   ~Decoration() override;
 
@@ -59,19 +59,13 @@ class Decoration : public Node {
   /// kind.
   virtual bool IsKind(DecorationKind kind) const = 0;
 
-  /// @return true if this decoration is of (or derives from) type |TO|
-  template <typename TO>
-  bool Is() const {
-    return IsKind(TO::Kind);
-  }
-
   /// @returns true if the node is valid
   bool IsValid() const override;
 
  protected:
   /// Constructor
   /// @param source the source of this decoration
-  explicit Decoration(const Source& source) : Node(source) {}
+  explicit Decoration(const Source& source) : Base(source) {}
 };
 
 /// As dynamically casts |deco| to the target type |TO|.

src/ast/decoration_test.cc

@@ -57,7 +57,7 @@ TEST_F(DecorationTest, AsIncorrectType) {
 }
 
 TEST_F(DecorationTest, Is) {
-  auto* decoration = create<ConstantIdDecoration>(1, Source{});
+  Decoration* decoration = create<ConstantIdDecoration>(1, Source{});
   EXPECT_TRUE(decoration->Is<VariableDecoration>());
   EXPECT_FALSE(decoration->Is<ArrayDecoration>());
 }

src/ast/discard_statement.cc

@@ -17,9 +17,11 @@
 namespace tint {
 namespace ast {
 
-DiscardStatement::DiscardStatement() : Statement() {}
+DiscardStatement::DiscardStatement() : Base() {}
 
-DiscardStatement::DiscardStatement(const Source& source) : Statement(source) {}
+DiscardStatement::DiscardStatement(const Source& source) : Base(source) {}
+
+DiscardStatement::DiscardStatement(DiscardStatement&&) = default;
 
 DiscardStatement::~DiscardStatement() = default;
 

src/ast/discard_statement.h

@@ -21,7 +21,7 @@ namespace tint {
 namespace ast {
 
 /// A discard statement
-class DiscardStatement : public Statement {
+class DiscardStatement : public Castable<DiscardStatement, Statement> {
  public:
   /// Constructor
   DiscardStatement();
@@ -29,7 +29,7 @@ class DiscardStatement : public Statement {
   /// @param source the discard statement source
   explicit DiscardStatement(const Source& source);
   /// Move constructor
-  DiscardStatement(DiscardStatement&&) = default;
+  DiscardStatement(DiscardStatement&&);
   ~DiscardStatement() override;
 
   /// @returns true if this is a discard statement

src/ast/else_statement.cc

@@ -17,18 +17,18 @@
 namespace tint {
 namespace ast {
 
-ElseStatement::ElseStatement(BlockStatement* body) : Statement(), body_(body) {}
+ElseStatement::ElseStatement(BlockStatement* body) : Base(), body_(body) {}
 
 ElseStatement::ElseStatement(Expression* condition, BlockStatement* body)
-    : Statement(), condition_(condition), body_(body) {}
+    : Base(), condition_(condition), body_(body) {}
 
 ElseStatement::ElseStatement(const Source& source, BlockStatement* body)
-    : Statement(source), body_(body) {}
+    : Base(source), body_(body) {}
 
 ElseStatement::ElseStatement(const Source& source,
                              Expression* condition,
                              BlockStatement* body)
-    : Statement(source), condition_(condition), body_(body) {}
+    : Base(source), condition_(condition), body_(body) {}
 
 ElseStatement::ElseStatement(ElseStatement&&) = default;
 

src/ast/else_statement.h

@@ -27,7 +27,7 @@ namespace tint {
 namespace ast {
 
 /// An else statement
-class ElseStatement : public Statement {
+class ElseStatement : public Castable<ElseStatement, Statement> {
  public:
   /// Constructor
   /// @param body the else body

src/ast/expression.cc

@@ -31,7 +31,9 @@ namespace ast {
 
 Expression::Expression() = default;
 
-Expression::Expression(const Source& source) : Node(source) {}
+Expression::Expression(const Source& source) : Base(source) {}
+
+Expression::Expression(Expression&&) = default;
 
 Expression::~Expression() = default;
 

src/ast/expression.h

@@ -35,7 +35,7 @@ class MemberAccessorExpression;
 class UnaryOpExpression;
 
 /// Base expression class
-class Expression : public Node {
+class Expression : public Castable<Expression, Node> {
  public:
   ~Expression() override;
 
@@ -109,7 +109,7 @@ class Expression : public Node {
   /// @param source the source of the expression
   explicit Expression(const Source& source);
   /// Move constructor
-  Expression(Expression&&) = default;
+  Expression(Expression&&);
 
  private:
   Expression(const Expression&) = delete;

src/ast/fallthrough_statement.cc

@@ -17,10 +17,12 @@
 namespace tint {
 namespace ast {
 
-FallthroughStatement::FallthroughStatement() : Statement() {}
+FallthroughStatement::FallthroughStatement() : Base() {}
 
 FallthroughStatement::FallthroughStatement(const Source& source)
-    : Statement(source) {}
+    : Base(source) {}
+
+FallthroughStatement::FallthroughStatement(FallthroughStatement&&) = default;
 
 FallthroughStatement::~FallthroughStatement() = default;
 

src/ast/fallthrough_statement.h

@@ -21,7 +21,7 @@ namespace tint {
 namespace ast {
 
 /// An fallthrough statement
-class FallthroughStatement : public Statement {
+class FallthroughStatement : public Castable<FallthroughStatement, Statement> {
  public:
   /// Constructor
   FallthroughStatement();
@@ -29,7 +29,7 @@ class FallthroughStatement : public Statement {
   /// @param source the source information
   explicit FallthroughStatement(const Source& source);
   /// Move constructor
-  FallthroughStatement(FallthroughStatement&&) = default;
+  FallthroughStatement(FallthroughStatement&&);
   ~FallthroughStatement() override;
 
   /// @returns true if this is an fallthrough statement

src/ast/float_literal.cc

@@ -21,7 +21,7 @@ namespace tint {
 namespace ast {
 
 FloatLiteral::FloatLiteral(ast::type::Type* type, float value)
-    : Literal(type), value_(value) {}
+    : Base(type), value_(value) {}
 
 FloatLiteral::~FloatLiteral() = default;
 

src/ast/float_literal.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace ast {
 
 /// A float literal
-class FloatLiteral : public Literal {
+class FloatLiteral : public Castable<FloatLiteral, Literal> {
  public:
   /// Constructor
   /// @param type the type of the literal

src/ast/function.cc

@@ -32,7 +32,7 @@ Function::Function(const std::string& name,
                    VariableList params,
                    type::Type* return_type,
                    BlockStatement* body)
-    : Node(),
+    : Base(),
       name_(name),
       params_(std::move(params)),
       return_type_(return_type),
@@ -43,7 +43,7 @@ Function::Function(const Source& source,
                    VariableList params,
                    type::Type* return_type,
                    BlockStatement* body)
-    : Node(source),
+    : Base(source),
       name_(name),
       params_(std::move(params)),
       return_type_(return_type),

src/ast/function.h

@@ -40,7 +40,7 @@ namespace tint {
 namespace ast {
 
 /// A Function statement.
-class Function : public Node {
+class Function : public Castable<Function, Node> {
  public:
   /// Information about a binding
   struct BindingInfo {

src/ast/function_decoration.cc

@@ -24,8 +24,7 @@ namespace ast {
 
 constexpr const DecorationKind FunctionDecoration::Kind;
 
-FunctionDecoration::FunctionDecoration(const Source& source)
+FunctionDecoration::FunctionDecoration(const Source& source) : Base(source) {}
-    : Decoration(source) {}
 
 FunctionDecoration::~FunctionDecoration() = default;
 

src/ast/function_decoration.h

@@ -28,7 +28,7 @@ class StageDecoration;
 class WorkgroupDecoration;
 
 /// A decoration attached to a function
-class FunctionDecoration : public Decoration {
+class FunctionDecoration : public Castable<FunctionDecoration, Decoration> {
  public:
   /// The kind of decoration that this type represents
   static constexpr const DecorationKind Kind = DecorationKind::kFunction;

src/ast/identifier_expression.cc

@@ -18,11 +18,11 @@ namespace tint {
 namespace ast {
 
 IdentifierExpression::IdentifierExpression(const std::string& name)
-    : Expression(), name_(name) {}
+    : Base(), name_(name) {}
 
 IdentifierExpression::IdentifierExpression(const Source& source,
                                            const std::string& name)
-    : Expression(source), name_(name) {}
+    : Base(source), name_(name) {}
 
 IdentifierExpression::IdentifierExpression(IdentifierExpression&&) = default;
 

src/ast/identifier_expression.h

@@ -26,7 +26,7 @@ namespace tint {
 namespace ast {
 
 /// An identifier expression
-class IdentifierExpression : public Expression {
+class IdentifierExpression : public Castable<IdentifierExpression, Expression> {
  public:
   /// Constructor
   /// @param name the name

src/ast/if_statement.cc

@@ -20,12 +20,12 @@ namespace tint {
 namespace ast {
 
 IfStatement::IfStatement(Expression* condition, BlockStatement* body)
-    : Statement(), condition_(condition), body_(body) {}
+    : Base(), condition_(condition), body_(body) {}
 
 IfStatement::IfStatement(const Source& source,
                          Expression* condition,
                          BlockStatement* body)
-    : Statement(source), condition_(condition), body_(body) {}
+    : Base(source), condition_(condition), body_(body) {}
 
 IfStatement::IfStatement(IfStatement&&) = default;
 

src/ast/if_statement.h

@@ -27,7 +27,7 @@ namespace tint {
 namespace ast {
 
 /// An if statement
-class IfStatement : public Statement {
+class IfStatement : public Castable<IfStatement, Statement> {
  public:
   /// Constructor
   /// @param condition the if condition

src/ast/int_literal.cc

@@ -17,7 +17,7 @@
 namespace tint {
 namespace ast {
 
-IntLiteral::IntLiteral(ast::type::Type* type) : Literal(type) {}
+IntLiteral::IntLiteral(ast::type::Type* type) : Base(type) {}
 
 IntLiteral::~IntLiteral() = default;
 

src/ast/int_literal.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace ast {
 
 /// An integer literal. This could be either signed or unsigned.
-class IntLiteral : public Literal {
+class IntLiteral : public Castable<IntLiteral, Literal> {
  public:
   ~IntLiteral() override;
 

src/ast/literal.h

@@ -31,7 +31,7 @@ class IntLiteral;
 class UintLiteral;
 
 /// Base class for a literal value
-class Literal : public Node {
+class Literal : public Castable<Literal, Node> {
  public:
   ~Literal() override;
 

src/ast/location_decoration.cc

@@ -20,7 +20,7 @@ namespace ast {
 constexpr const DecorationKind LocationDecoration::Kind;
 
 LocationDecoration::LocationDecoration(uint32_t val, const Source& source)
-    : VariableDecoration(source), value_(val) {}
+    : Base(source), value_(val) {}
 
 LocationDecoration::~LocationDecoration() = default;
 
@@ -29,7 +29,7 @@ DecorationKind LocationDecoration::GetKind() const {
 }
 
 bool LocationDecoration::IsKind(DecorationKind kind) const {
-  return kind == Kind || VariableDecoration::IsKind(kind);
+  return kind == Kind || Base::IsKind(kind);
 }
 
 bool LocationDecoration::IsLocation() const {

src/ast/location_decoration.h

@@ -23,7 +23,8 @@ namespace tint {
 namespace ast {
 
 /// A location decoration
-class LocationDecoration : public VariableDecoration {
+class LocationDecoration
+    : public Castable<LocationDecoration, VariableDecoration> {
  public:
   /// The kind of decoration that this type represents
   static constexpr const DecorationKind Kind = DecorationKind::kLocation;

src/ast/loop_statement.cc

@@ -18,12 +18,12 @@ namespace tint {
 namespace ast {
 
 LoopStatement::LoopStatement(BlockStatement* body, BlockStatement* continuing)
-    : Statement(), body_(body), continuing_(continuing) {}
+    : Base(), body_(body), continuing_(continuing) {}
 
 LoopStatement::LoopStatement(const Source& source,
                              BlockStatement* body,
                              BlockStatement* continuing)
-    : Statement(source), body_(body), continuing_(continuing) {}
+    : Base(source), body_(body), continuing_(continuing) {}
 
 LoopStatement::LoopStatement(LoopStatement&&) = default;
 

src/ast/loop_statement.h

@@ -25,7 +25,7 @@ namespace tint {
 namespace ast {
 
 /// A loop statement
-class LoopStatement : public Statement {
+class LoopStatement : public Castable<LoopStatement, Statement> {
  public:
   /// Constructor
   /// @param body the body statements

src/ast/member_accessor_expression.cc

@@ -21,12 +21,12 @@ MemberAccessorExpression::MemberAccessorExpression() = default;
 
 MemberAccessorExpression::MemberAccessorExpression(Expression* structure,
                                                    IdentifierExpression* member)
-    : Expression(), struct_(structure), member_(member) {}
+    : Base(), struct_(structure), member_(member) {}
 
 MemberAccessorExpression::MemberAccessorExpression(const Source& source,
                                                    Expression* structure,
                                                    IdentifierExpression* member)
-    : Expression(source), struct_(structure), member_(member) {}
+    : Base(source), struct_(structure), member_(member) {}
 
 MemberAccessorExpression::MemberAccessorExpression(MemberAccessorExpression&&) =
     default;

src/ast/member_accessor_expression.h

@@ -27,7 +27,8 @@ namespace tint {
 namespace ast {
 
 /// A member accessor expression
-class MemberAccessorExpression : public Expression {
+class MemberAccessorExpression
+    : public Castable<MemberAccessorExpression, Expression> {
  public:
   /// Constructor
   MemberAccessorExpression();

src/ast/node.cc

@@ -23,6 +23,8 @@ Node::Node() = default;
 
 Node::Node(const Source& source) : source_(source) {}
 
+Node::Node(Node&&) = default;
+
 Node::~Node() = default;
 
 void Node::make_indent(std::ostream& out, size_t indent) const {

src/ast/node.h

@@ -18,15 +18,16 @@
 #include <ostream>
 #include <string>
 
+#include "src/castable.h"
 #include "src/source.h"
 
 namespace tint {
 namespace ast {
 
 /// AST base class node
-class Node {
+class Node : public Castable<Node> {
  public:
-  virtual ~Node();
+  ~Node() override;
 
   /// @returns the node source data
   const Source& source() const { return source_; }
@@ -53,7 +54,7 @@ class Node {
   /// @param source The input source for the node
   explicit Node(const Source& source);
   /// Move constructor
-  Node(Node&&) = default;
+  Node(Node&&);
 
   /// Writes indent into stream
   /// @param out the stream to write to

src/ast/null_literal.cc

@@ -17,7 +17,7 @@
 namespace tint {
 namespace ast {
 
-NullLiteral::NullLiteral(ast::type::Type* type) : Literal(type) {}
+NullLiteral::NullLiteral(ast::type::Type* type) : Base(type) {}
 
 NullLiteral::~NullLiteral() = default;
 

src/ast/null_literal.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace ast {
 
 /// A null literal
-class NullLiteral : public Literal {
+class NullLiteral : public Castable<NullLiteral, Literal> {
  public:
   /// Constructor
   /// @param type the type

src/ast/return_statement.cc

@@ -17,15 +17,14 @@
 namespace tint {
 namespace ast {
 
-ReturnStatement::ReturnStatement() : Statement() {}
+ReturnStatement::ReturnStatement() : Base() {}
 
-ReturnStatement::ReturnStatement(const Source& source) : Statement(source) {}
+ReturnStatement::ReturnStatement(const Source& source) : Base(source) {}
 
-ReturnStatement::ReturnStatement(Expression* value)
+ReturnStatement::ReturnStatement(Expression* value) : Base(), value_(value) {}
-    : Statement(), value_(value) {}
 
 ReturnStatement::ReturnStatement(const Source& source, Expression* value)
-    : Statement(source), value_(value) {}
+    : Base(source), value_(value) {}
 
 ReturnStatement::ReturnStatement(ReturnStatement&&) = default;
 

src/ast/return_statement.h

@@ -25,7 +25,7 @@ namespace tint {
 namespace ast {
 
 /// A return statement
-class ReturnStatement : public Statement {
+class ReturnStatement : public Castable<ReturnStatement, Statement> {
  public:
   /// Constructor
   ReturnStatement();

src/ast/scalar_constructor_expression.cc

@@ -17,15 +17,14 @@
 namespace tint {
 namespace ast {
 
-ScalarConstructorExpression::ScalarConstructorExpression()
+ScalarConstructorExpression::ScalarConstructorExpression() : Base() {}
-    : ConstructorExpression() {}
 
 ScalarConstructorExpression::ScalarConstructorExpression(Literal* literal)
     : literal_(literal) {}
 
 ScalarConstructorExpression::ScalarConstructorExpression(const Source& source,
                                                          Literal* litearl)
-    : ConstructorExpression(source), literal_(litearl) {}
+    : Base(source), literal_(litearl) {}
 
 ScalarConstructorExpression::ScalarConstructorExpression(
     ScalarConstructorExpression&&) = default;

src/ast/scalar_constructor_expression.h

@@ -25,7 +25,8 @@ namespace tint {
 namespace ast {
 
 /// A scalar constructor
-class ScalarConstructorExpression : public ConstructorExpression {
+class ScalarConstructorExpression
+    : public Castable<ScalarConstructorExpression, ConstructorExpression> {
  public:
   /// Constructor
   ScalarConstructorExpression();

src/ast/set_decoration.cc

@@ -18,7 +18,7 @@ namespace tint {
 namespace ast {
 
 SetDecoration::SetDecoration(uint32_t val, const Source& source)
-    : VariableDecoration(source), value_(val) {}
+    : Base(source), value_(val) {}
 
 SetDecoration::~SetDecoration() = default;
 

src/ast/set_decoration.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace ast {
 
 /// A set decoration
-class SetDecoration : public VariableDecoration {
+class SetDecoration : public Castable<SetDecoration, VariableDecoration> {
  public:
   /// constructor
   /// @param value the set value

src/ast/sint_literal.cc

@@ -18,7 +18,7 @@ namespace tint {
 namespace ast {
 
 SintLiteral::SintLiteral(ast::type::Type* type, int32_t value)
-    : IntLiteral(type), value_(value) {}
+    : Base(type), value_(value) {}
 
 SintLiteral::~SintLiteral() = default;
 

src/ast/sint_literal.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace ast {
 
 /// A signed int literal
-class SintLiteral : public IntLiteral {
+class SintLiteral : public Castable<SintLiteral, IntLiteral> {
  public:
   /// Constructor
   /// @param type the type

src/ast/stage_decoration.cc

@@ -20,7 +20,7 @@ namespace ast {
 constexpr const DecorationKind StageDecoration::Kind;
 
 StageDecoration::StageDecoration(ast::PipelineStage stage, const Source& source)
-    : FunctionDecoration(source), stage_(stage) {}
+    : Base(source), stage_(stage) {}
 
 StageDecoration::~StageDecoration() = default;
 
@@ -29,7 +29,7 @@ DecorationKind StageDecoration::GetKind() const {
 }
 
 bool StageDecoration::IsKind(DecorationKind kind) const {
-  return kind == Kind || FunctionDecoration::IsKind(kind);
+  return kind == Kind || Base::IsKind(kind);
 }
 
 bool StageDecoration::IsStage() const {

src/ast/stage_decoration.h

@@ -22,7 +22,7 @@ namespace tint {
 namespace ast {
 
 /// A workgroup decoration
-class StageDecoration : public FunctionDecoration {
+class StageDecoration : public Castable<StageDecoration, FunctionDecoration> {
  public:
   /// The kind of decoration that this type represents
   static constexpr const DecorationKind Kind = DecorationKind::kStage;

src/ast/statement.cc

@@ -36,7 +36,7 @@ namespace ast {
 
 Statement::Statement() = default;
 
-Statement::Statement(const Source& source) : Node(source) {}
+Statement::Statement(const Source& source) : Base(source) {}
 
 Statement::Statement(Statement&&) = default;
 

src/ast/statement.h

@@ -39,7 +39,7 @@ class SwitchStatement;
 class VariableDeclStatement;
 
 /// Base statement class
-class Statement : public Node {
+class Statement : public Castable<Statement, Node> {
  public:
   ~Statement() override;
 

src/ast/stride_decoration.cc

@@ -20,14 +20,14 @@ namespace ast {
 constexpr const DecorationKind StrideDecoration::Kind;
 
 StrideDecoration::StrideDecoration(uint32_t stride, const Source& source)
-    : ArrayDecoration(source), stride_(stride) {}
+    : Base(source), stride_(stride) {}
 
 DecorationKind StrideDecoration::GetKind() const {
   return Kind;
 }
 
 bool StrideDecoration::IsKind(DecorationKind kind) const {
-  return kind == Kind || ArrayDecoration::IsKind(kind);
+  return kind == Kind || Base::IsKind(kind);
 }
 
 bool StrideDecoration::IsStride() const {

src/ast/stride_decoration.h

@@ -25,7 +25,7 @@ namespace tint {
 namespace ast {
 
 /// A stride decoration
-class StrideDecoration : public ArrayDecoration {
+class StrideDecoration : public Castable<StrideDecoration, ArrayDecoration> {
  public:
   /// The kind of decoration that this type represents
   static constexpr const DecorationKind Kind = DecorationKind::kStride;

src/ast/struct.cc

@@ -17,23 +17,23 @@
 namespace tint {
 namespace ast {
 
-Struct::Struct() : Node() {}
+Struct::Struct() : Base() {}
 
 Struct::Struct(StructMemberList members)
-    : Node(), members_(std::move(members)) {}
+    : Base(), members_(std::move(members)) {}
 
 Struct::Struct(StructDecorationList decorations, StructMemberList members)
-    : Node(),
+    : Base(),
       decorations_(std::move(decorations)),
       members_(std::move(members)) {}
 
 Struct::Struct(const Source& source, StructMemberList members)
-    : Node(source), members_(std::move(members)) {}
+    : Base(source), members_(std::move(members)) {}
 
 Struct::Struct(const Source& source,
                StructDecorationList decorations,
                StructMemberList members)
-    : Node(source),
+    : Base(source),
       decorations_(std::move(decorations)),
       members_(std::move(members)) {}
 

src/ast/struct.h

@@ -27,7 +27,7 @@ namespace tint {
 namespace ast {
 
 /// A struct statement.
-class Struct : public Node {
+class Struct : public Castable<Struct, Node> {
  public:
   /// Create a new empty struct statement
   Struct();

src/ast/struct_block_decoration.cc

@@ -18,7 +18,7 @@ namespace tint {
 namespace ast {
 
 StructBlockDecoration::StructBlockDecoration(const Source& source)
-    : StructDecoration(source) {}
+    : Base(source) {}
 
 StructBlockDecoration::~StructBlockDecoration() = default;
 

src/ast/struct_block_decoration.h

@@ -25,7 +25,8 @@ namespace tint {
 namespace ast {
 
 /// The struct decorations
-class StructBlockDecoration : public StructDecoration {
+class StructBlockDecoration
+    : public Castable<StructBlockDecoration, StructDecoration> {
  public:
   /// constructor
   /// @param source the source of this decoration

src/ast/struct_decoration.cc

@@ -19,7 +19,7 @@ namespace ast {
 
 constexpr const DecorationKind StructDecoration::Kind;
 
-StructDecoration::StructDecoration(const Source& source) : Decoration(source) {}
+StructDecoration::StructDecoration(const Source& source) : Base(source) {}
 
 StructDecoration::~StructDecoration() = default;
 

src/ast/struct_decoration.h

@@ -25,7 +25,7 @@ namespace tint {
 namespace ast {
 
 /// The struct decorations
-class StructDecoration : public Decoration {
+class StructDecoration : public Castable<StructDecoration, Decoration> {
  public:
   /// The kind of decoration that this type represents
   static constexpr const DecorationKind Kind = DecorationKind::kStruct;

src/ast/struct_member.cc

@@ -24,13 +24,13 @@ StructMember::StructMember() = default;
 StructMember::StructMember(const std::string& name,
                            type::Type* type,
                            StructMemberDecorationList decorations)
-    : Node(), name_(name), type_(type), decorations_(std::move(decorations)) {}
+    : Base(), name_(name), type_(type), decorations_(std::move(decorations)) {}
 
 StructMember::StructMember(const Source& source,
                            const std::string& name,
                            type::Type* type,
                            StructMemberDecorationList decorations)
-    : Node(source),
+    : Base(source),
       name_(name),
       type_(type),
       decorations_(std::move(decorations)) {}

src/ast/struct_member.h

@@ -29,7 +29,7 @@ namespace tint {
 namespace ast {
 
 /// A struct member statement.
-class StructMember : public Node {
+class StructMember : public Castable<StructMember, Node> {
  public:
   /// Create a new empty struct member statement
   StructMember();

src/ast/struct_member_decoration.cc

@@ -24,7 +24,7 @@ namespace ast {
 constexpr const DecorationKind StructMemberDecoration::Kind;
 
 StructMemberDecoration::StructMemberDecoration(const Source& source)
-    : Decoration(source) {}
+    : Base(source) {}
 
 StructMemberDecoration::~StructMemberDecoration() = default;
 

src/ast/struct_member_decoration.h

@@ -27,7 +27,8 @@ namespace ast {
 class StructMemberOffsetDecoration;
 
 /// A decoration attached to a struct member
-class StructMemberDecoration : public Decoration {
+class StructMemberDecoration
+    : public Castable<StructMemberDecoration, Decoration> {
  public:
   /// The kind of decoration that this type represents
   static constexpr const DecorationKind Kind = DecorationKind::kStructMember;

src/ast/struct_member_offset_decoration.cc

@@ -21,14 +21,14 @@ constexpr const DecorationKind StructMemberOffsetDecoration::Kind;
 
 StructMemberOffsetDecoration::StructMemberOffsetDecoration(uint32_t offset,
                                                            const Source& source)
-    : StructMemberDecoration(source), offset_(offset) {}
+    : Base(source), offset_(offset) {}
 
 DecorationKind StructMemberOffsetDecoration::GetKind() const {
   return Kind;
 }
 
 bool StructMemberOffsetDecoration::IsKind(DecorationKind kind) const {
-  return kind == Kind || StructMemberDecoration::IsKind(kind);
+  return kind == Kind || Base::IsKind(kind);
 }
 
 bool StructMemberOffsetDecoration::IsOffset() const {

src/ast/struct_member_offset_decoration.h

@@ -25,7 +25,8 @@ namespace tint {
 namespace ast {
 
 /// A struct member offset decoration
-class StructMemberOffsetDecoration : public StructMemberDecoration {
+class StructMemberOffsetDecoration
+    : public Castable<StructMemberOffsetDecoration, StructMemberDecoration> {
  public:
   /// The kind of decoration that this type represents
   static constexpr const DecorationKind Kind =

src/ast/switch_statement.cc

@@ -19,7 +19,7 @@
 namespace tint {
 namespace ast {
 
-SwitchStatement::SwitchStatement() : Statement() {}
+SwitchStatement::SwitchStatement() : Base() {}
 
 SwitchStatement::SwitchStatement(Expression* condition, CaseStatementList body)
     : condition_(condition), body_(body) {}
@@ -27,7 +27,7 @@ SwitchStatement::SwitchStatement(Expression* condition, CaseStatementList body)
 SwitchStatement::SwitchStatement(const Source& source,
                                  Expression* condition,
                                  CaseStatementList body)
-    : Statement(source), condition_(condition), body_(body) {}
+    : Base(source), condition_(condition), body_(body) {}
 
 bool SwitchStatement::IsSwitch() const {
   return true;

src/ast/switch_statement.h

@@ -27,7 +27,7 @@ namespace tint {
 namespace ast {
 
 /// A switch statement
-class SwitchStatement : public Statement {
+class SwitchStatement : public Castable<SwitchStatement, Statement> {
  public:
   /// Constructor
   SwitchStatement();

src/ast/type_constructor_expression.cc

@@ -17,17 +17,16 @@
 namespace tint {
 namespace ast {
 
-TypeConstructorExpression::TypeConstructorExpression()
+TypeConstructorExpression::TypeConstructorExpression() : Base() {}
-    : ConstructorExpression() {}
 
 TypeConstructorExpression::TypeConstructorExpression(type::Type* type,
                                                      ExpressionList values)
-    : ConstructorExpression(), type_(type), values_(std::move(values)) {}
+    : Base(), type_(type), values_(std::move(values)) {}
 
 TypeConstructorExpression::TypeConstructorExpression(const Source& source,
                                                      type::Type* type,
                                                      ExpressionList values)
-    : ConstructorExpression(source), type_(type), values_(std::move(values)) {}
+    : Base(source), type_(type), values_(std::move(values)) {}
 
 TypeConstructorExpression::TypeConstructorExpression(
     TypeConstructorExpression&&) = default;

src/ast/type_constructor_expression.h

@@ -25,7 +25,8 @@ namespace tint {
 namespace ast {
 
 /// A type specific constructor
-class TypeConstructorExpression : public ConstructorExpression {
+class TypeConstructorExpression
+    : public Castable<TypeConstructorExpression, ConstructorExpression> {
  public:
   TypeConstructorExpression();
   /// Constructor

src/ast/type_decoration.cc

@@ -23,7 +23,7 @@ namespace ast {
 
 constexpr const DecorationKind TypeDecoration::Kind;
 
-TypeDecoration::TypeDecoration(const Source& source) : Decoration(source) {}
+TypeDecoration::TypeDecoration(const Source& source) : Base(source) {}
 
 TypeDecoration::~TypeDecoration() = default;