Use 'final' specifier on leaf classes

Tint makes heavy use of RTTI via virtual methods. Give the compiler the
opportunity to optimize away some of these virtuals.

Bug: tint:1383
Change-Id: I28edfaa0a05bb1a9c506c61c0084542c0aeb37f0
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/82745
Reviewed-by: James Price <jrprice@google.com>
Reviewed-by: David Neto <dneto@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>

src/tint/ast/alias.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace ast {
 
 /// A type alias type. Holds a name and pointer to another type.
-class Alias : public Castable<Alias, TypeDecl> {
+class Alias final : public Castable<Alias, TypeDecl> {
  public:
   /// Constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/array.h

@@ -27,7 +27,7 @@ namespace ast {
 class Expression;
 
 /// An array type. If size is zero then it is a runtime array.
-class Array : public Castable<Array, Type> {
+class Array final : public Castable<Array, Type> {
  public:
   /// Constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/assignment_statement.h

@@ -22,7 +22,8 @@ namespace tint {
 namespace ast {
 
 /// An assignment statement
-class AssignmentStatement : public Castable<AssignmentStatement, Statement> {
+class AssignmentStatement final
+    : public Castable<AssignmentStatement, Statement> {
  public:
   /// Constructor
   /// @param program_id the identifier of the program that owns this node

src/tint/ast/atomic.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace ast {
 
 /// An atomic type.
-class Atomic : public Castable<Atomic, Type> {
+class Atomic final : public Castable<Atomic, Type> {
  public:
   /// Constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/binary_expression.h

@@ -44,7 +44,7 @@ enum class BinaryOp {
 };
 
 /// An binary expression
-class BinaryExpression : public Castable<BinaryExpression, Expression> {
+class BinaryExpression final : public Castable<BinaryExpression, Expression> {
  public:
   /// Constructor
   /// @param program_id the identifier of the program that owns this node

src/tint/ast/binding_attribute.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace ast {
 
 /// A binding attribute
-class BindingAttribute : public Castable<BindingAttribute, Attribute> {
+class BindingAttribute final : public Castable<BindingAttribute, Attribute> {
  public:
   /// Constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/bitcast_expression.h

@@ -24,7 +24,7 @@ namespace ast {
 class Type;
 
 /// A bitcast expression
-class BitcastExpression : public Castable<BitcastExpression, Expression> {
+class BitcastExpression final : public Castable<BitcastExpression, Expression> {
  public:
   /// Constructor
   /// @param program_id the identifier of the program that owns this node

src/tint/ast/block_statement.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace ast {
 
 /// A block statement
-class BlockStatement : public Castable<BlockStatement, Statement> {
+class BlockStatement final : public Castable<BlockStatement, Statement> {
  public:
   /// Constructor
   /// @param program_id the identifier of the program that owns this node

src/tint/ast/bool.h

@@ -29,7 +29,7 @@ namespace tint {
 namespace ast {
 
 /// A boolean type
-class Bool : public Castable<Bool, Type> {
+class Bool final : public Castable<Bool, Type> {
  public:
   /// Constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/bool_literal_expression.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace ast {
 
 /// A boolean literal
-class BoolLiteralExpression
+class BoolLiteralExpression final
     : public Castable<BoolLiteralExpression, LiteralExpression> {
  public:
   /// Constructor

src/tint/ast/break_statement.h

@@ -21,7 +21,7 @@ namespace tint {
 namespace ast {
 
 /// An break statement
-class BreakStatement : public Castable<BreakStatement, Statement> {
+class BreakStatement final : public Castable<BreakStatement, Statement> {
  public:
   /// Constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/builtin_attribute.h

@@ -24,7 +24,7 @@ namespace tint {
 namespace ast {
 
 /// A builtin attribute
-class BuiltinAttribute : public Castable<BuiltinAttribute, Attribute> {
+class BuiltinAttribute final : public Castable<BuiltinAttribute, Attribute> {
  public:
   /// constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/call_expression.h

@@ -29,7 +29,7 @@ class IdentifierExpression;
 /// * sem::Builtin
 /// * sem::TypeConstructor
 /// * sem::TypeConversion
-class CallExpression : public Castable<CallExpression, Expression> {
+class CallExpression final : public Castable<CallExpression, Expression> {
  public:
   /// Constructor
   /// @param program_id the identifier of the program that owns this node

src/tint/ast/call_statement.h

@@ -22,7 +22,7 @@ namespace tint {
 namespace ast {
 
 /// A call expression
-class CallStatement : public Castable<CallStatement, Statement> {
+class CallStatement final : public Castable<CallStatement, Statement> {
  public:
   /// Constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/case_statement.h

@@ -27,7 +27,7 @@ namespace ast {
 using CaseSelectorList = std::vector<const IntLiteralExpression*>;
 
 /// A case statement
-class CaseStatement : public Castable<CaseStatement, Statement> {
+class CaseStatement final : public Castable<CaseStatement, Statement> {
  public:
   /// Constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/continue_statement.h

@@ -21,7 +21,7 @@ namespace tint {
 namespace ast {
 
 /// An continue statement
-class ContinueStatement : public Castable<ContinueStatement, Statement> {
+class ContinueStatement final : public Castable<ContinueStatement, Statement> {
  public:
   /// Constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/depth_multisampled_texture.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace ast {
 
 /// A multisampled depth texture type.
-class DepthMultisampledTexture
+class DepthMultisampledTexture final
     : public Castable<DepthMultisampledTexture, Texture> {
  public:
   /// Constructor

src/tint/ast/depth_texture.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace ast {
 
 /// A depth texture type.
-class DepthTexture : public Castable<DepthTexture, Texture> {
+class DepthTexture final : public Castable<DepthTexture, Texture> {
  public:
   /// Constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/disable_validation_attribute.h

@@ -52,7 +52,7 @@ enum class DisabledValidation {
 /// An internal attribute used to tell the validator to ignore specific
 /// violations. Typically generated by transforms that need to produce ASTs that
 /// would otherwise cause validation errors.
-class DisableValidationAttribute
+class DisableValidationAttribute final
     : public Castable<DisableValidationAttribute, InternalAttribute> {
  public:
   /// Constructor

src/tint/ast/discard_statement.h

@@ -21,7 +21,7 @@ namespace tint {
 namespace ast {
 
 /// A discard statement
-class DiscardStatement : public Castable<DiscardStatement, Statement> {
+class DiscardStatement final : public Castable<DiscardStatement, Statement> {
  public:
   /// Constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/else_statement.h

@@ -24,7 +24,7 @@ namespace tint {
 namespace ast {
 
 /// An else statement
-class ElseStatement : public Castable<ElseStatement, Statement> {
+class ElseStatement final : public Castable<ElseStatement, Statement> {
  public:
   /// Constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/external_texture.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace ast {
 
 /// An external texture type
-class ExternalTexture : public Castable<ExternalTexture, Texture> {
+class ExternalTexture final : public Castable<ExternalTexture, Texture> {
  public:
   /// Constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/f32.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace ast {
 
 /// A float 32 type
-class F32 : public Castable<F32, Type> {
+class F32 final : public Castable<F32, Type> {
  public:
   /// Constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/fallthrough_statement.h

@@ -21,7 +21,8 @@ namespace tint {
 namespace ast {
 
 /// An fallthrough statement
-class FallthroughStatement : public Castable<FallthroughStatement, Statement> {
+class FallthroughStatement final
+    : public Castable<FallthroughStatement, Statement> {
  public:
   /// Constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/float_literal_expression.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace ast {
 
 /// A float literal
-class FloatLiteralExpression
+class FloatLiteralExpression final
     : public Castable<FloatLiteralExpression, LiteralExpression> {
  public:
   /// Constructor

src/tint/ast/for_loop_statement.h

@@ -23,7 +23,7 @@ namespace ast {
 class Expression;
 
 /// A for loop statement
-class ForLoopStatement : public Castable<ForLoopStatement, Statement> {
+class ForLoopStatement final : public Castable<ForLoopStatement, Statement> {
  public:
   /// Constructor
   /// @param program_id the identifier of the program that owns this node

src/tint/ast/function.h

@@ -33,7 +33,7 @@ namespace tint {
 namespace ast {
 
 /// A Function statement.
-class Function : public Castable<Function, Node> {
+class Function final : public Castable<Function, Node> {
  public:
   /// Create a function
   /// @param program_id the identifier of the program that owns this node

src/tint/ast/group_attribute.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace ast {
 
 /// A group attribute
-class GroupAttribute : public Castable<GroupAttribute, Attribute> {
+class GroupAttribute final : public Castable<GroupAttribute, Attribute> {
  public:
   /// constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/i32.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace ast {
 
 /// A signed int 32 type.
-class I32 : public Castable<I32, Type> {
+class I32 final : public Castable<I32, Type> {
  public:
   /// Constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/id_attribute.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace ast {
 
 /// An id attribute for pipeline-overridable constants
-class IdAttribute : public Castable<IdAttribute, Attribute> {
+class IdAttribute final : public Castable<IdAttribute, Attribute> {
  public:
   /// Create an id attribute.
   /// @param pid the identifier of the program that owns this node

src/tint/ast/identifier_expression.h

@@ -21,7 +21,8 @@ namespace tint {
 namespace ast {
 
 /// An identifier expression
-class IdentifierExpression : public Castable<IdentifierExpression, Expression> {
+class IdentifierExpression final
+    : public Castable<IdentifierExpression, Expression> {
  public:
   /// Constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/if_statement.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace ast {
 
 /// An if statement
-class IfStatement : public Castable<IfStatement, Statement> {
+class IfStatement final : public Castable<IfStatement, Statement> {
  public:
   /// Constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/index_accessor_expression.h

@@ -21,7 +21,7 @@ namespace tint {
 namespace ast {
 
 /// An index accessor expression
-class IndexAccessorExpression
+class IndexAccessorExpression final
     : public Castable<IndexAccessorExpression, Expression> {
  public:
   /// Constructor

src/tint/ast/interpolate_attribute.h

@@ -30,7 +30,8 @@ enum class InterpolationType { kPerspective, kLinear, kFlat };
 enum class InterpolationSampling { kNone = -1, kCenter, kCentroid, kSample };
 
 /// An interpolate attribute
-class InterpolateAttribute : public Castable<InterpolateAttribute, Attribute> {
+class InterpolateAttribute final
+    : public Castable<InterpolateAttribute, Attribute> {
  public:
   /// Create an interpolate attribute.
   /// @param pid the identifier of the program that owns this node

src/tint/ast/invariant_attribute.h

@@ -23,7 +23,8 @@ namespace tint {
 namespace ast {
 
 /// The invariant attribute
-class InvariantAttribute : public Castable<InvariantAttribute, Attribute> {
+class InvariantAttribute final
+    : public Castable<InvariantAttribute, Attribute> {
  public:
   /// constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/location_attribute.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace ast {
 
 /// A location attribute
-class LocationAttribute : public Castable<LocationAttribute, Attribute> {
+class LocationAttribute final : public Castable<LocationAttribute, Attribute> {
  public:
   /// constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/loop_statement.h

@@ -21,7 +21,7 @@ namespace tint {
 namespace ast {
 
 /// A loop statement
-class LoopStatement : public Castable<LoopStatement, Statement> {
+class LoopStatement final : public Castable<LoopStatement, Statement> {
  public:
   /// Constructor
   /// @param program_id the identifier of the program that owns this node

src/tint/ast/matrix.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace ast {
 
 /// A matrix type
-class Matrix : public Castable<Matrix, Type> {
+class Matrix final : public Castable<Matrix, Type> {
  public:
   /// Constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/member_accessor_expression.h

@@ -21,7 +21,7 @@ namespace tint {
 namespace ast {
 
 /// A member accessor expression
-class MemberAccessorExpression
+class MemberAccessorExpression final
     : public Castable<MemberAccessorExpression, Expression> {
  public:
   /// Constructor

src/tint/ast/module.h

@@ -28,7 +28,7 @@ class TypeDecl;
 
 /// Module holds the top-level AST types, functions and global variables used by
 /// a Program.
-class Module : public Castable<Module, Node> {
+class Module final : public Castable<Module, Node> {
  public:
   /// Constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/multisampled_texture.h

@@ -23,7 +23,8 @@ namespace tint {
 namespace ast {
 
 /// A multisampled texture type.
-class MultisampledTexture : public Castable<MultisampledTexture, Texture> {
+class MultisampledTexture final
+    : public Castable<MultisampledTexture, Texture> {
  public:
   /// Constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/phony_expression.h

@@ -22,7 +22,7 @@ namespace ast {
 
 /// Represents the `_` of a phony assignment `_ = <expr>`
 /// @see https://www.w3.org/TR/WGSL/#phony-assignment-section
-class PhonyExpression : public Castable<PhonyExpression, Expression> {
+class PhonyExpression final : public Castable<PhonyExpression, Expression> {
  public:
   /// Constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/pointer.h

@@ -25,7 +25,7 @@ namespace tint {
 namespace ast {
 
 /// A pointer type.
-class Pointer : public Castable<Pointer, Type> {
+class Pointer final : public Castable<Pointer, Type> {
  public:
   /// Constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/return_statement.h

@@ -22,7 +22,7 @@ namespace tint {
 namespace ast {
 
 /// A return statement
-class ReturnStatement : public Castable<ReturnStatement, Statement> {
+class ReturnStatement final : public Castable<ReturnStatement, Statement> {
  public:
   /// Constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/sampled_texture.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace ast {
 
 /// A sampled texture type.
-class SampledTexture : public Castable<SampledTexture, Texture> {
+class SampledTexture final : public Castable<SampledTexture, Texture> {
  public:
   /// Constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/sampler.h

@@ -36,7 +36,7 @@ enum class SamplerKind {
 std::ostream& operator<<(std::ostream& out, SamplerKind kind);
 
 /// A sampler type.
-class Sampler : public Castable<Sampler, Type> {
+class Sampler final : public Castable<Sampler, Type> {
  public:
   /// Constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/sint_literal_expression.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace ast {
 
 /// A signed int literal
-class SintLiteralExpression
+class SintLiteralExpression final
     : public Castable<SintLiteralExpression, IntLiteralExpression> {
  public:
   /// Constructor

src/tint/ast/stage_attribute.h

@@ -24,7 +24,7 @@ namespace tint {
 namespace ast {
 
 /// A workgroup attribute
-class StageAttribute : public Castable<StageAttribute, Attribute> {
+class StageAttribute final : public Castable<StageAttribute, Attribute> {
  public:
   /// constructor
   /// @param program_id the identifier of the program that owns this node

src/tint/ast/storage_texture.h

@@ -50,7 +50,7 @@ enum class TexelFormat {
 std::ostream& operator<<(std::ostream& out, TexelFormat format);
 
 /// A storage texture type.
-class StorageTexture : public Castable<StorageTexture, Texture> {
+class StorageTexture final : public Castable<StorageTexture, Texture> {
  public:
   /// Constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/stride_attribute.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace ast {
 
 /// A stride attribute
-class StrideAttribute : public Castable<StrideAttribute, Attribute> {
+class StrideAttribute final : public Castable<StrideAttribute, Attribute> {
  public:
   /// constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/struct.h

@@ -26,7 +26,7 @@ namespace tint {
 namespace ast {
 
 /// A struct statement.
-class Struct : public Castable<Struct, TypeDecl> {
+class Struct final : public Castable<Struct, TypeDecl> {
  public:
   /// Create a new struct statement
   /// @param pid the identifier of the program that owns this node

src/tint/ast/struct_block_attribute.h

@@ -24,7 +24,8 @@ namespace tint {
 namespace ast {
 
 /// The struct block attribute
-class StructBlockAttribute : public Castable<StructBlockAttribute, Attribute> {
+class StructBlockAttribute final
+    : public Castable<StructBlockAttribute, Attribute> {
  public:
   /// Constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/struct_member.h

@@ -27,7 +27,7 @@ namespace ast {
 class Type;
 
 /// A struct member statement.
-class StructMember : public Castable<StructMember, Node> {
+class StructMember final : public Castable<StructMember, Node> {
  public:
   /// Create a new struct member statement
   /// @param pid the identifier of the program that owns this node

src/tint/ast/struct_member_align_attribute.h

@@ -24,7 +24,7 @@ namespace tint {
 namespace ast {
 
 /// A struct member align attribute
-class StructMemberAlignAttribute
+class StructMemberAlignAttribute final
     : public Castable<StructMemberAlignAttribute, Attribute> {
  public:
   /// constructor

src/tint/ast/struct_member_offset_attribute.h

@@ -32,7 +32,7 @@ namespace ast {
 /// trivial for the Resolver to handle `@offset(n)` or `@size(n)` /
 /// `@align(n)` attributes, so this is what we do, keeping all the layout
 /// logic in one place.
-class StructMemberOffsetAttribute
+class StructMemberOffsetAttribute final
     : public Castable<StructMemberOffsetAttribute, Attribute> {
  public:
   /// constructor

src/tint/ast/struct_member_size_attribute.h

@@ -24,7 +24,7 @@ namespace tint {
 namespace ast {
 
 /// A struct member size attribute
-class StructMemberSizeAttribute
+class StructMemberSizeAttribute final
     : public Castable<StructMemberSizeAttribute, Attribute> {
  public:
   /// constructor

src/tint/ast/switch_statement.h

@@ -22,7 +22,7 @@ namespace tint {
 namespace ast {
 
 /// A switch statement
-class SwitchStatement : public Castable<SwitchStatement, Statement> {
+class SwitchStatement final : public Castable<SwitchStatement, Statement> {
  public:
   /// Constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/type_name.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace ast {
 
 /// A named type (i.e. struct or alias)
-class TypeName : public Castable<TypeName, Type> {
+class TypeName final : public Castable<TypeName, Type> {
  public:
   /// Constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/u32.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace ast {
 
 /// A unsigned int 32 type.
-class U32 : public Castable<U32, Type> {
+class U32 final : public Castable<U32, Type> {
  public:
   /// Constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/uint_literal_expression.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace ast {
 
 /// A uint literal
-class UintLiteralExpression
+class UintLiteralExpression final
     : public Castable<UintLiteralExpression, IntLiteralExpression> {
  public:
   /// Constructor

src/tint/ast/unary_op_expression.h

@@ -22,7 +22,7 @@ namespace tint {
 namespace ast {
 
 /// A unary op expression
-class UnaryOpExpression : public Castable<UnaryOpExpression, Expression> {
+class UnaryOpExpression final : public Castable<UnaryOpExpression, Expression> {
  public:
   /// Constructor
   /// @param program_id the identifier of the program that owns this node

src/tint/ast/variable.h

@@ -113,7 +113,7 @@ struct VariableBindingPoint {
 ///     defaulting syntax for a "var" declared inside a function.
 ///   - "let" is always StorageClass::kNone.
 ///   - formal parameter is always StorageClass::kNone.
-class Variable : public Castable<Variable, Node> {
+class Variable final : public Castable<Variable, Node> {
  public:
   /// Create a variable
   /// @param program_id the identifier of the program that owns this node

src/tint/ast/variable_decl_statement.h

@@ -22,7 +22,7 @@ namespace tint {
 namespace ast {
 
 /// A variable declaration statement
-class VariableDeclStatement
+class VariableDeclStatement final
     : public Castable<VariableDeclStatement, Statement> {
  public:
   /// Constructor

src/tint/ast/vector.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace ast {
 
 /// A vector type.
-class Vector : public Castable<Vector, Type> {
+class Vector final : public Castable<Vector, Type> {
  public:
   /// Constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/void.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace ast {
 
 /// A void type
-class Void : public Castable<Void, Type> {
+class Void final : public Castable<Void, Type> {
  public:
   /// Constructor
   /// @param pid the identifier of the program that owns this node

src/tint/ast/workgroup_attribute.h

@@ -27,7 +27,8 @@ namespace ast {
 class Expression;
 
 /// A workgroup attribute
-class WorkgroupAttribute : public Castable<WorkgroupAttribute, Attribute> {
+class WorkgroupAttribute final
+    : public Castable<WorkgroupAttribute, Attribute> {
  public:
   /// constructor
   /// @param pid the identifier of the program that owns this node

src/tint/builtin_table.cc

@@ -43,7 +43,7 @@ class NumberMatcher;
 class TypeMatcher;
 
 /// A special type that matches all TypeMatchers
-class Any : public Castable<Any, sem::Type> {
+class Any final : public Castable<Any, sem::Type> {
  public:
   Any() = default;
   ~Any() override = default;

src/tint/reader/spirv/function.cc

@@ -647,7 +647,7 @@ class StructuredTraverser {
 
 /// A StatementBuilder for ast::SwitchStatement
 /// @see StatementBuilder
-struct SwitchStatementBuilder
+struct SwitchStatementBuilder final
     : public Castable<SwitchStatementBuilder, StatementBuilder> {
   /// Constructor
   /// @param cond the switch statement condition
@@ -674,7 +674,7 @@ struct SwitchStatementBuilder
 
 /// A StatementBuilder for ast::IfStatement
 /// @see StatementBuilder
-struct IfStatementBuilder
+struct IfStatementBuilder final
     : public Castable<IfStatementBuilder, StatementBuilder> {
   /// Constructor
   /// @param c the if-statement condition
@@ -696,7 +696,7 @@ struct IfStatementBuilder
 
 /// A StatementBuilder for ast::LoopStatement
 /// @see StatementBuilder
-struct LoopStatementBuilder
+struct LoopStatementBuilder final
     : public Castable<LoopStatementBuilder, StatementBuilder> {
   /// @param builder the program builder
   /// @returns the built ast::LoopStatement

src/tint/reader/spirv/parser_type.h

@@ -92,7 +92,7 @@ class Type : public Castable<Type> {
 using TypeList = std::vector<const Type*>;
 
 /// `void` type
-struct Void : public Castable<Void, Type> {
+struct Void final : public Castable<Void, Type> {
   /// @param b the ProgramBuilder used to construct the AST types
   /// @returns the constructed ast::Type node for the given type
   const ast::Type* Build(ProgramBuilder& b) const override;
@@ -104,7 +104,7 @@ struct Void : public Castable<Void, Type> {
 };
 
 /// `bool` type
-struct Bool : public Castable<Bool, Type> {
+struct Bool final : public Castable<Bool, Type> {
   /// @param b the ProgramBuilder used to construct the AST types
   /// @returns the constructed ast::Type node for the given type
   const ast::Type* Build(ProgramBuilder& b) const override;
@@ -116,7 +116,7 @@ struct Bool : public Castable<Bool, Type> {
 };
 
 /// `u32` type
-struct U32 : public Castable<U32, Type> {
+struct U32 final : public Castable<U32, Type> {
   /// @param b the ProgramBuilder used to construct the AST types
   /// @returns the constructed ast::Type node for the given type
   const ast::Type* Build(ProgramBuilder& b) const override;
@@ -128,7 +128,7 @@ struct U32 : public Castable<U32, Type> {
 };
 
 /// `f32` type
-struct F32 : public Castable<F32, Type> {
+struct F32 final : public Castable<F32, Type> {
   /// @param b the ProgramBuilder used to construct the AST types
   /// @returns the constructed ast::Type node for the given type
   const ast::Type* Build(ProgramBuilder& b) const override;
@@ -140,7 +140,7 @@ struct F32 : public Castable<F32, Type> {
 };
 
 /// `i32` type
-struct I32 : public Castable<I32, Type> {
+struct I32 final : public Castable<I32, Type> {
   /// @param b the ProgramBuilder used to construct the AST types
   /// @returns the constructed ast::Type node for the given type
   const ast::Type* Build(ProgramBuilder& b) const override;
@@ -152,7 +152,7 @@ struct I32 : public Castable<I32, Type> {
 };
 
 /// `ptr<SC, T>` type
-struct Pointer : public Castable<Pointer, Type> {
+struct Pointer final : public Castable<Pointer, Type> {
   /// Constructor
   /// @param ty the store type
   /// @param sc the pointer storage class
@@ -180,7 +180,7 @@ struct Pointer : public Castable<Pointer, Type> {
 /// `ref<SC, T>` type
 /// Note this has no AST representation, but is used for type tracking in the
 /// reader.
-struct Reference : public Castable<Reference, Type> {
+struct Reference final : public Castable<Reference, Type> {
   /// Constructor
   /// @param ty the referenced type
   /// @param sc the reference storage class
@@ -206,7 +206,7 @@ struct Reference : public Castable<Reference, Type> {
 };
 
 /// `vecN<T>` type
-struct Vector : public Castable<Vector, Type> {
+struct Vector final : public Castable<Vector, Type> {
   /// Constructor
   /// @param ty the element type
   /// @param sz the number of elements in the vector
@@ -232,7 +232,7 @@ struct Vector : public Castable<Vector, Type> {
 };
 
 /// `matNxM<T>` type
-struct Matrix : public Castable<Matrix, Type> {
+struct Matrix final : public Castable<Matrix, Type> {
   /// Constructor
   /// @param ty the matrix element type
   /// @param c the number of columns in the matrix
@@ -261,7 +261,7 @@ struct Matrix : public Castable<Matrix, Type> {
 };
 
 /// `array<T, N>` type
-struct Array : public Castable<Array, Type> {
+struct Array final : public Castable<Array, Type> {
   /// Constructor
   /// @param el the element type
   /// @param sz the number of elements in the array. 0 represents runtime-sized
@@ -291,7 +291,7 @@ struct Array : public Castable<Array, Type> {
 };
 
 /// `sampler` type
-struct Sampler : public Castable<Sampler, Type> {
+struct Sampler final : public Castable<Sampler, Type> {
   /// Constructor
   /// @param k the sampler kind
   explicit Sampler(ast::SamplerKind k);
@@ -328,7 +328,7 @@ struct Texture : public Castable<Texture, Type> {
 };
 
 /// `texture_depth_D` type
-struct DepthTexture : public Castable<DepthTexture, Texture> {
+struct DepthTexture final : public Castable<DepthTexture, Texture> {
   /// Constructor
   /// @param d the texture dimensions
   explicit DepthTexture(ast::TextureDimension d);
@@ -348,7 +348,7 @@ struct DepthTexture : public Castable<DepthTexture, Texture> {
 };
 
 /// `texture_depth_multisampled_D` type
-struct DepthMultisampledTexture
+struct DepthMultisampledTexture final
     : public Castable<DepthMultisampledTexture, Texture> {
   /// Constructor
   /// @param d the texture dimensions
@@ -369,7 +369,8 @@ struct DepthMultisampledTexture
 };
 
 /// `texture_multisampled_D<T>` type
-struct MultisampledTexture : public Castable<MultisampledTexture, Texture> {
+struct MultisampledTexture final
+    : public Castable<MultisampledTexture, Texture> {
   /// Constructor
   /// @param d the texture dimensions
   /// @param t the multisampled texture type
@@ -393,7 +394,7 @@ struct MultisampledTexture : public Castable<MultisampledTexture, Texture> {
 };
 
 /// `texture_D<T>` type
-struct SampledTexture : public Castable<SampledTexture, Texture> {
+struct SampledTexture final : public Castable<SampledTexture, Texture> {
   /// Constructor
   /// @param d the texture dimensions
   /// @param t the sampled texture type
@@ -417,7 +418,7 @@ struct SampledTexture : public Castable<SampledTexture, Texture> {
 };
 
 /// `texture_storage_D<F>` type
-struct StorageTexture : public Castable<StorageTexture, Texture> {
+struct StorageTexture final : public Castable<StorageTexture, Texture> {
   /// Constructor
   /// @param d the texture dimensions
   /// @param f the storage image format
@@ -467,7 +468,7 @@ struct Named : public Castable<Named, Type> {
 };
 
 /// `type T = N` type
-struct Alias : public Castable<Alias, Named> {
+struct Alias final : public Castable<Alias, Named> {
   /// Constructor
   /// @param n the alias name
   /// @param t the aliased type
@@ -486,7 +487,7 @@ struct Alias : public Castable<Alias, Named> {
 };
 
 /// `struct N { ... };` type
-struct Struct : public Castable<Struct, Named> {
+struct Struct final : public Castable<Struct, Named> {
   /// Constructor
   /// @param n the struct name
   /// @param m the member types

src/tint/resolver/validation_test.cc

@@ -47,13 +47,13 @@ namespace {
 
 using ResolverValidationTest = ResolverTest;
 
-class FakeStmt : public Castable<FakeStmt, ast::Statement> {
+class FakeStmt final : public Castable<FakeStmt, ast::Statement> {
  public:
   FakeStmt(ProgramID pid, Source src) : Base(pid, src) {}
   FakeStmt* Clone(CloneContext*) const override { return nullptr; }
 };
 
-class FakeExpr : public Castable<FakeExpr, ast::Expression> {
+class FakeExpr final : public Castable<FakeExpr, ast::Expression> {
  public:
   FakeExpr(ProgramID pid, Source src) : Base(pid, src) {}
   FakeExpr* Clone(CloneContext*) const override { return nullptr; }

src/tint/sem/array.h

@@ -32,7 +32,7 @@ namespace tint {
 namespace sem {
 
 /// Array holds the semantic information for Array nodes.
-class Array : public Castable<Array, Type> {
+class Array final : public Castable<Array, Type> {
  public:
   /// Constructor
   /// @param element the array element type

src/tint/sem/atomic_type.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace sem {
 
 /// A atomic type.
-class Atomic : public Castable<Atomic, Type> {
+class Atomic final : public Castable<Atomic, Type> {
  public:
   /// Constructor
   /// @param subtype the atomic type

src/tint/sem/block_statement.h

@@ -64,7 +64,7 @@ class BlockStatement : public Castable<BlockStatement, CompoundStatement> {
 };
 
 /// The root block statement for a function
-class FunctionBlockStatement
+class FunctionBlockStatement final
     : public Castable<FunctionBlockStatement, BlockStatement> {
  public:
   /// Constructor
@@ -76,7 +76,8 @@ class FunctionBlockStatement
 };
 
 /// Holds semantic information about a loop body block or for-loop body block
-class LoopBlockStatement : public Castable<LoopBlockStatement, BlockStatement> {
+class LoopBlockStatement final
+    : public Castable<LoopBlockStatement, BlockStatement> {
  public:
   /// Constructor
   /// @param declaration the AST node for this block statement

src/tint/sem/bool_type.h

@@ -29,7 +29,7 @@ namespace tint {
 namespace sem {
 
 /// A boolean type
-class Bool : public Castable<Bool, Type> {
+class Bool final : public Castable<Bool, Type> {
  public:
   /// Constructor
   Bool();

src/tint/sem/builtin.h

@@ -72,7 +72,7 @@ bool IsBarrierBuiltin(BuiltinType i);
 bool IsAtomicBuiltin(BuiltinType i);
 
 /// Builtin holds the semantic information for a builtin function.
-class Builtin : public Castable<Builtin, CallTarget> {
+class Builtin final : public Castable<Builtin, CallTarget> {
  public:
   /// Constructor
   /// @param type the builtin type

src/tint/sem/call.h

@@ -25,7 +25,7 @@ namespace sem {
 
 /// Call is the base class for semantic nodes that hold semantic information for
 /// ast::CallExpression nodes.
-class Call : public Castable<Call, Expression> {
+class Call final : public Castable<Call, Expression> {
  public:
   /// Constructor
   /// @param declaration the AST node

src/tint/sem/depth_multisampled_texture_type.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace sem {
 
 /// A multisampled depth texture type.
-class DepthMultisampledTexture
+class DepthMultisampledTexture final
     : public Castable<DepthMultisampledTexture, Texture> {
  public:
   /// Constructor

src/tint/sem/depth_texture_type.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace sem {
 
 /// A depth texture type.
-class DepthTexture : public Castable<DepthTexture, Texture> {
+class DepthTexture final : public Castable<DepthTexture, Texture> {
  public:
   /// Constructor
   /// @param dim the dimensionality of the texture

src/tint/sem/external_texture_type.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace sem {
 
 /// An external texture type
-class ExternalTexture : public Castable<ExternalTexture, Texture> {
+class ExternalTexture final : public Castable<ExternalTexture, Texture> {
  public:
   /// Constructor
   ExternalTexture();

src/tint/sem/f32_type.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace sem {
 
 /// A float 32 type
-class F32 : public Castable<F32, Type> {
+class F32 final : public Castable<F32, Type> {
  public:
   /// Constructor
   F32();

src/tint/sem/for_loop_statement.h

@@ -30,7 +30,8 @@ namespace tint {
 namespace sem {
 
 /// Holds semantic information about a for-loop statement
-class ForLoopStatement : public Castable<ForLoopStatement, CompoundStatement> {
+class ForLoopStatement final
+    : public Castable<ForLoopStatement, CompoundStatement> {
  public:
   /// Constructor
   /// @param declaration the AST node for this for-loop statement

src/tint/sem/function.h

@@ -52,7 +52,7 @@ struct WorkgroupDimension {
 using WorkgroupSize = std::array<WorkgroupDimension, 3>;
 
 /// Function holds the semantic information for function nodes.
-class Function : public Castable<Function, CallTarget> {
+class Function final : public Castable<Function, CallTarget> {
  public:
   /// A vector of [Variable*, ast::VariableBindingPoint] pairs
   using VariableBindings =

src/tint/sem/i32_type.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace sem {
 
 /// A signed int 32 type.
-class I32 : public Castable<I32, Type> {
+class I32 final : public Castable<I32, Type> {
  public:
   /// Constructor
   I32();

src/tint/sem/if_statement.h

@@ -32,7 +32,7 @@ namespace tint {
 namespace sem {
 
 /// Holds semantic information about an if statement
-class IfStatement : public Castable<IfStatement, CompoundStatement> {
+class IfStatement final : public Castable<IfStatement, CompoundStatement> {
  public:
   /// Constructor
   /// @param declaration the AST node for this if statement
@@ -60,7 +60,7 @@ class IfStatement : public Castable<IfStatement, CompoundStatement> {
 };
 
 /// Holds semantic information about an else statement
-class ElseStatement : public Castable<ElseStatement, CompoundStatement> {
+class ElseStatement final : public Castable<ElseStatement, CompoundStatement> {
  public:
   /// Constructor
   /// @param declaration the AST node for this else statement

src/tint/sem/loop_statement.h

@@ -28,7 +28,7 @@ namespace tint {
 namespace sem {
 
 /// Holds semantic information about a loop statement
-class LoopStatement : public Castable<LoopStatement, CompoundStatement> {
+class LoopStatement final : public Castable<LoopStatement, CompoundStatement> {
  public:
   /// Constructor
   /// @param declaration the AST node for this loop statement
@@ -43,7 +43,7 @@ class LoopStatement : public Castable<LoopStatement, CompoundStatement> {
 };
 
 /// Holds semantic information about a loop continuing block
-class LoopContinuingBlockStatement
+class LoopContinuingBlockStatement final
     : public Castable<LoopContinuingBlockStatement, BlockStatement> {
  public:
   /// Constructor

src/tint/sem/matrix_type.h

@@ -26,7 +26,7 @@ namespace sem {
 class Vector;
 
 /// A matrix type
-class Matrix : public Castable<Matrix, Type> {
+class Matrix final : public Castable<Matrix, Type> {
  public:
   /// Constructor
   /// @param column_type the type of a column of the matrix

src/tint/sem/member_accessor_expression.h

@@ -54,7 +54,7 @@ class MemberAccessorExpression
 /// StructMemberAccess holds the semantic information for a
 /// ast::MemberAccessorExpression node that represents an access to a structure
 /// member.
-class StructMemberAccess
+class StructMemberAccess final
     : public Castable<StructMemberAccess, MemberAccessorExpression> {
  public:
   /// Constructor
@@ -81,7 +81,7 @@ class StructMemberAccess
 
 /// Swizzle holds the semantic information for a ast::MemberAccessorExpression
 /// node that represents a vector swizzle.
-class Swizzle : public Castable<Swizzle, MemberAccessorExpression> {
+class Swizzle final : public Castable<Swizzle, MemberAccessorExpression> {
  public:
   /// Constructor
   /// @param declaration the AST node

src/tint/sem/module.h

@@ -29,7 +29,7 @@ namespace tint::sem {
 
 /// Module holds the top-level semantic types, functions and global variables
 /// used by a Program.
-class Module : public Castable<Module, Node> {
+class Module final : public Castable<Module, Node> {
  public:
   /// Constructor
   /// @param dep_ordered_decls the dependency-ordered module-scope declarations

src/tint/sem/multisampled_texture_type.h

@@ -23,7 +23,8 @@ namespace tint {
 namespace sem {
 
 /// A multisampled texture type.
-class MultisampledTexture : public Castable<MultisampledTexture, Texture> {
+class MultisampledTexture final
+    : public Castable<MultisampledTexture, Texture> {
  public:
   /// Constructor
   /// @param dim the dimensionality of the texture

src/tint/sem/pointer_type.h

@@ -25,7 +25,7 @@ namespace tint {
 namespace sem {
 
 /// A pointer type.
-class Pointer : public Castable<Pointer, Type> {
+class Pointer final : public Castable<Pointer, Type> {
  public:
   /// Constructor
   /// @param subtype the pointee type

src/tint/sem/reference_type.h

@@ -25,7 +25,7 @@ namespace tint {
 namespace sem {
 
 /// A reference type.
-class Reference : public Castable<Reference, Type> {
+class Reference final : public Castable<Reference, Type> {
  public:
   /// Constructor
   /// @param subtype the pointee type

src/tint/sem/sampled_texture_type.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace sem {
 
 /// A sampled texture type.
-class SampledTexture : public Castable<SampledTexture, Texture> {
+class SampledTexture final : public Castable<SampledTexture, Texture> {
  public:
   /// Constructor
   /// @param dim the dimensionality of the texture

src/tint/sem/sampler_type.h

@@ -24,7 +24,7 @@ namespace tint {
 namespace sem {
 
 /// A sampler type.
-class Sampler : public Castable<Sampler, Type> {
+class Sampler final : public Castable<Sampler, Type> {
  public:
   /// Constructor
   /// @param kind the kind of sampler

src/tint/sem/storage_texture_type.h

@@ -27,7 +27,7 @@ namespace sem {
 class Manager;
 
 /// A storage texture type.
-class StorageTexture : public Castable<StorageTexture, Texture> {
+class StorageTexture final : public Castable<StorageTexture, Texture> {
  public:
   /// Constructor
   /// @param dim the dimensionality of the texture

src/tint/sem/struct.h

@@ -54,7 +54,7 @@ enum class PipelineStageUsage {
 };
 
 /// Struct holds the semantic information for structures.
-class Struct : public Castable<Struct, Type> {
+class Struct final : public Castable<Struct, Type> {
  public:
   /// Constructor
   /// @param declaration the AST structure declaration

src/tint/sem/switch_statement.h

@@ -29,7 +29,8 @@ namespace tint {
 namespace sem {
 
 /// Holds semantic information about an switch statement
-class SwitchStatement : public Castable<SwitchStatement, CompoundStatement> {
+class SwitchStatement final
+    : public Castable<SwitchStatement, CompoundStatement> {
  public:
   /// Constructor
   /// @param declaration the AST node for this switch statement
@@ -47,7 +48,7 @@ class SwitchStatement : public Castable<SwitchStatement, CompoundStatement> {
 };
 
 /// Holds semantic information about a switch case statement
-class CaseStatement : public Castable<CaseStatement, CompoundStatement> {
+class CaseStatement final : public Castable<CaseStatement, CompoundStatement> {
  public:
   /// Constructor
   /// @param declaration the AST node for this case statement

src/tint/sem/type_constructor.h

@@ -21,7 +21,7 @@ namespace tint {
 namespace sem {
 
 /// TypeConstructor is the CallTarget for a type constructor.
-class TypeConstructor : public Castable<TypeConstructor, CallTarget> {
+class TypeConstructor final : public Castable<TypeConstructor, CallTarget> {
  public:
   /// Constructor
   /// @param type the type that's being constructed

src/tint/sem/type_conversion.h

@@ -21,7 +21,7 @@ namespace tint {
 namespace sem {
 
 /// TypeConversion is the CallTarget for a type conversion (cast).
-class TypeConversion : public Castable<TypeConversion, CallTarget> {
+class TypeConversion final : public Castable<TypeConversion, CallTarget> {
  public:
   /// Constructor
   /// @param type the target type of the cast

src/tint/sem/type_manager.h

@@ -25,7 +25,7 @@
 namespace tint::sem {
 
 /// The type manager holds all the pointers to the known types.
-class Manager : public utils::UniqueAllocator<Type> {
+class Manager final : public utils::UniqueAllocator<Type> {
  public:
   /// Iterator is the type returned by begin() and end()
   using Iterator = utils::BlockAllocator<Type>::ConstIterator;

src/tint/sem/u32_type.h

@@ -23,7 +23,7 @@ namespace tint {
 namespace sem {
 
 /// A unsigned int 32 type.
-class U32 : public Castable<U32, Type> {
+class U32 final : public Castable<U32, Type> {
  public:
   /// Constructor
   U32();