Flatten ast::Decoration class hierarchy

Remove the decoration groupings (Array, Function, Struct,
StructMember, Type, Variable), such that all *Decoration classes now
subclass ast::Decoration directly. This allows for decorations to be
used in multiple places; for example, builtin decorations are now
valid for both variables and struct members.

Checking that decoration lists only contain decorations that are valid
for the node that they are attached to is now done inside the
validator.

Change-Id: Ie8c0e53e5730a7dedea50a1dec8f26f9e7b00e8d
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/44320
Commit-Queue: James Price <jrprice@google.com>
Reviewed-by: Ben Clayton <bclayton@chromium.org>

BUILD.gn

@@ -230,8 +230,6 @@ source_set("libtint_core_src") {
     "src/ast/access_decoration.h",
     "src/ast/array_accessor_expression.cc",
     "src/ast/array_accessor_expression.h",
-    "src/ast/array_decoration.cc",
-    "src/ast/array_decoration.h",
     "src/ast/assignment_statement.cc",
     "src/ast/assignment_statement.h",
     "src/ast/binary_expression.cc",
@@ -276,8 +274,6 @@ source_set("libtint_core_src") {
     "src/ast/float_literal.h",
     "src/ast/function.cc",
     "src/ast/function.h",
-    "src/ast/function_decoration.cc",
-    "src/ast/function_decoration.h",
     "src/ast/group_decoration.cc",
     "src/ast/group_decoration.h",
     "src/ast/identifier_expression.cc",
@@ -320,20 +316,14 @@ source_set("libtint_core_src") {
     "src/ast/struct.h",
     "src/ast/struct_block_decoration.cc",
     "src/ast/struct_block_decoration.h",
-    "src/ast/struct_decoration.cc",
-    "src/ast/struct_decoration.h",
     "src/ast/struct_member.cc",
     "src/ast/struct_member.h",
-    "src/ast/struct_member_decoration.cc",
-    "src/ast/struct_member_decoration.h",
     "src/ast/struct_member_offset_decoration.cc",
     "src/ast/struct_member_offset_decoration.h",
     "src/ast/switch_statement.cc",
     "src/ast/switch_statement.h",
     "src/ast/type_constructor_expression.cc",
     "src/ast/type_constructor_expression.h",
-    "src/ast/type_decoration.cc",
-    "src/ast/type_decoration.h",
     "src/ast/uint_literal.cc",
     "src/ast/uint_literal.h",
     "src/ast/unary_op.cc",
@@ -344,8 +334,6 @@ source_set("libtint_core_src") {
     "src/ast/variable.h",
     "src/ast/variable_decl_statement.cc",
     "src/ast/variable_decl_statement.h",
-    "src/ast/variable_decoration.cc",
-    "src/ast/variable_decoration.h",
     "src/ast/workgroup_decoration.cc",
     "src/ast/workgroup_decoration.h",
     "src/block_allocator.h",
@@ -797,7 +785,6 @@ source_set("tint_unittests_core_src") {
     "src/ast/case_statement_test.cc",
     "src/ast/constant_id_decoration_test.cc",
     "src/ast/continue_statement_test.cc",
-    "src/ast/decoration_test.cc",
     "src/ast/discard_statement_test.cc",
     "src/ast/else_statement_test.cc",
     "src/ast/fallthrough_statement_test.cc",
@@ -883,6 +870,7 @@ source_set("tint_unittests_core_src") {
     "src/utils/unique_vector_test.cc",
     "src/validator/validator_builtins_test.cc",
     "src/validator/validator_control_block_test.cc",
+    "src/validator/validator_decoration_test.cc",
     "src/validator/validator_function_test.cc",
     "src/validator/validator_test.cc",
     "src/validator/validator_test_helper.cc",

src/CMakeLists.txt

@@ -44,8 +44,6 @@ set(TINT_LIB_SRCS
   ast/access_decoration.h
   ast/array_accessor_expression.cc
   ast/array_accessor_expression.h
-  ast/array_decoration.cc
-  ast/array_decoration.h
   ast/assignment_statement.cc
   ast/assignment_statement.h
   ast/binary_expression.cc
@@ -90,8 +88,6 @@ set(TINT_LIB_SRCS
   ast/float_literal.h
   ast/function.cc
   ast/function.h
-  ast/function_decoration.cc
-  ast/function_decoration.h
   ast/group_decoration.cc
   ast/group_decoration.h
   ast/identifier_expression.cc
@@ -134,20 +130,14 @@ set(TINT_LIB_SRCS
   ast/struct.h
   ast/struct_block_decoration.cc
   ast/struct_block_decoration.h
-  ast/struct_decoration.cc
-  ast/struct_decoration.h
   ast/struct_member.cc
   ast/struct_member.h
-  ast/struct_member_decoration.cc
-  ast/struct_member_decoration.h
   ast/struct_member_offset_decoration.cc
   ast/struct_member_offset_decoration.h
   ast/switch_statement.cc
   ast/switch_statement.h
   ast/type_constructor_expression.cc
   ast/type_constructor_expression.h
-  ast/type_decoration.cc
-  ast/type_decoration.h
   ast/uint_literal.cc
   ast/uint_literal.h
   ast/unary_op.cc
@@ -156,8 +146,6 @@ set(TINT_LIB_SRCS
   ast/unary_op_expression.h
   ast/variable.cc
   ast/variable.h
-  ast/variable_decoration.cc
-  ast/variable_decoration.h
   ast/variable_decl_statement.cc
   ast/variable_decl_statement.h
   ast/workgroup_decoration.cc
@@ -426,7 +414,6 @@ if(${TINT_BUILD_TESTS})
     ast/case_statement_test.cc
     ast/constant_id_decoration_test.cc
     ast/continue_statement_test.cc
-    ast/decoration_test.cc
     ast/discard_statement_test.cc
     ast/else_statement_test.cc
     ast/fallthrough_statement_test.cc
@@ -506,6 +493,7 @@ if(${TINT_BUILD_TESTS})
     utils/unique_vector_test.cc
     validator/validator_builtins_test.cc
     validator/validator_control_block_test.cc
+    validator/validator_decoration_test.cc
     validator/validator_function_test.cc
     validator/validator_test.cc
     validator/validator_type_test.cc

src/ast/access_decoration.h

@@ -16,13 +16,13 @@
 #define SRC_AST_ACCESS_DECORATION_H_
 
 #include "src/ast/access_control.h"
-#include "src/ast/type_decoration.h"
+#include "src/ast/decoration.h"
 
 namespace tint {
 namespace ast {
 
 /// An access decoration
-class AccessDecoration : public Castable<AccessDecoration, TypeDecoration> {
+class AccessDecoration : public Castable<AccessDecoration, Decoration> {
  public:
   /// constructor
   /// @param source the source of this decoration

src/ast/binding_decoration.h

@@ -15,14 +15,13 @@
 #ifndef SRC_AST_BINDING_DECORATION_H_
 #define SRC_AST_BINDING_DECORATION_H_
 
-#include "src/ast/variable_decoration.h"
+#include "src/ast/decoration.h"
 
 namespace tint {
 namespace ast {
 
 /// A binding decoration
-class BindingDecoration
-    : public Castable<BindingDecoration, VariableDecoration> {
+class BindingDecoration : public Castable<BindingDecoration, Decoration> {
  public:
   /// constructor
   /// @param value the binding value

src/ast/builtin_decoration.h

@@ -16,14 +16,13 @@
 #define SRC_AST_BUILTIN_DECORATION_H_
 
 #include "src/ast/builtin.h"
-#include "src/ast/variable_decoration.h"
+#include "src/ast/decoration.h"
 
 namespace tint {
 namespace ast {
 
 /// A builtin decoration
-class BuiltinDecoration
-    : public Castable<BuiltinDecoration, VariableDecoration> {
+class BuiltinDecoration : public Castable<BuiltinDecoration, Decoration> {
  public:
   /// constructor
   /// @param source the source of this decoration

src/ast/constant_id_decoration.h

@@ -15,14 +15,13 @@
 #ifndef SRC_AST_CONSTANT_ID_DECORATION_H_
 #define SRC_AST_CONSTANT_ID_DECORATION_H_
 
-#include "src/ast/variable_decoration.h"
+#include "src/ast/decoration.h"
 
 namespace tint {
 namespace ast {
 
 /// A constant id decoration
-class ConstantIdDecoration
-    : public Castable<ConstantIdDecoration, VariableDecoration> {
+class ConstantIdDecoration : public Castable<ConstantIdDecoration, Decoration> {
  public:
   /// constructor
   /// @param source the source of this decoration

src/ast/decoration.cc

@@ -21,23 +21,5 @@ namespace ast {
 
 Decoration::~Decoration() = default;
 
-std::ostream& operator<<(std::ostream& out, DecorationKind data) {
-  switch (data) {
-    case DecorationKind::kArray:
-      return out << "array";
-    case DecorationKind::kFunction:
-      return out << "function";
-    case DecorationKind::kStruct:
-      return out << "struct";
-    case DecorationKind::kStructMember:
-      return out << "struct member";
-    case DecorationKind::kType:
-      return out << "type";
-    case DecorationKind::kVariable:
-      return out << "variable";
-  }
-  return out << "<unknown>";
-}
-
 }  // namespace ast
 }  // namespace tint

src/ast/decoration.h

@@ -22,26 +22,11 @@
 namespace tint {
 namespace ast {
 
-/// The decoration kind enumerator
-enum class DecorationKind {
-  kArray,
-  kFunction,
-  kStruct,
-  kStructMember,
-  kType,
-  kVariable,
-};
-
-std::ostream& operator<<(std::ostream& out, DecorationKind data);
-
 /// The base class for all decorations
 class Decoration : public Castable<Decoration, Node> {
  public:
   ~Decoration() override;
 
-  /// @return the decoration kind
-  virtual DecorationKind GetKind() const = 0;
-
  protected:
   /// Constructor
   /// @param source the source of this decoration

src/ast/function.cc

@@ -28,7 +28,7 @@ Function::Function(const Source& source,
                    VariableList params,
                    type::Type* return_type,
                    BlockStatement* body,
-                   FunctionDecorationList decorations)
+                   DecorationList decorations)
     : Base(source),
       symbol_(symbol),
       params_(std::move(params)),