commit 940af9f2c87b436559b97c53763aa9eaaf1254eb

Author: Jeremy Roman <jbroman@chromium.org>

Date:   Wed Nov 15 16:24:54 2023 +0000

    Use C++20 features to simplify blink::NativeValueTraitsBase.

    These allow some of the metaprogramming bits to be simplified a little.

    Change-Id: I052b4397586d21348401616e1792afdb9662f975

    Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5030335

    Reviewed-by: Yuki Shiino <yukishiino@chromium.org>

    Commit-Queue: Jeremy Roman <jbroman@chromium.org>

    Cr-Commit-Position: refs/heads/main@{#1224978}

diff --git a/third_party/blink/renderer/bindings/core/v8/native_value_traits.h b/third_party/blink/renderer/bindings/core/v8/native_value_traits.h

index 7fc91d14acc71..1e5a0790df6da 100644

--- a/third_party/blink/renderer/bindings/core/v8/native_value_traits.h

+++ b/third_party/blink/renderer/bindings/core/v8/native_value_traits.h

@@ -5,6 +5,7 @@

 #ifndef THIRD_PARTY_BLINK_RENDERER_BINDINGS_CORE_V8_NATIVE_VALUE_TRAITS_H_

 #define THIRD_PARTY_BLINK_RENDERER_BINDINGS_CORE_V8_NATIVE_VALUE_TRAITS_H_

+#include <concepts>

 #include <type_traits>

 #include "third_party/blink/renderer/bindings/core/v8/idl_types_base.h"

@@ -30,7 +31,7 @@ class ExceptionState;

 //     return toInt32(isolate, value, exceptionState, NormalConversion);

 //   }

 // }

-template <typename T, typename SFINAEHelper = void>

+template <typename T>

 struct NativeValueTraits;

 // This declaration serves only as a blueprint for specializations: the

@@ -45,22 +46,15 @@ struct NativeValueTraits;

 namespace bindings {

-template <typename T, typename = void>

-struct NativeValueTraitsHasIsNull : std::false_type {};

-

 template <typename T>

-struct NativeValueTraitsHasIsNull<

-    T,

-    std::void_t<decltype(std::declval<T>().IsNull())>> : std::true_type {};

+struct ImplTypeFor {

+  using type = T;

+};

 template <typename T>

-struct NativeValueTraitsHasNullValue {

-  // true if |T| supports IDL null value.

-  static constexpr bool value =

-      // ScriptValue, String, and union types have IsNull member function.

-      bindings::NativeValueTraitsHasIsNull<T>::value ||

-      // Pointer types have nullptr as IDL null value.

-      std::is_pointer<T>::value;

+  requires std::derived_from<T, IDLBase>

+struct ImplTypeFor<T> {

+  using type = typename T::ImplType;

 };

 }  // namespace bindings

@@ -78,37 +72,17 @@ struct NativeValueTraitsHasNullValue {

 // If present, |NullValue()| will be used when converting from the nullable type

 // T?, and should be used if the impl type has an existing "null" state. If not

 // present, WTF::Optional will be used to wrap the type.

-template <typename T, typename SFINAEHelper = void>

-struct NativeValueTraitsBase {

-  STATIC_ONLY(NativeValueTraitsBase);

-

-  using ImplType = T;

-

-  static constexpr bool has_null_value =

-      bindings::NativeValueTraitsHasNullValue<ImplType>::value;

-

-  template <typename... ExtraArgs>

-  static decltype(auto) ArgumentValue(v8::Isolate* isolate,

-                                      int argument_index,

-                                      v8::Local<v8::Value> value,

-                                      ExceptionState& exception_state,

-                                      ExtraArgs... extra_args) {

-    return NativeValueTraits<std::remove_pointer_t<T>>::NativeValue(

-        isolate, value, exception_state,

-        std::forward<ExtraArgs>(extra_args)...);

-  }

-};

-

 template <typename T>

-struct NativeValueTraitsBase<

-    T,

-    std::enable_if_t<std::is_base_of<IDLBase, T>::value>> {

+struct NativeValueTraitsBase {

   STATIC_ONLY(NativeValueTraitsBase);

-  using ImplType = typename T::ImplType;

+  using ImplType = bindings::ImplTypeFor<T>::type;

+  // Pointer types have nullptr as IDL null value.

+  // ScriptValue, String, and union types have IsNull member function.

   static constexpr bool has_null_value =

-      bindings::NativeValueTraitsHasNullValue<ImplType>::value;

+      std::is_pointer_v<ImplType> ||

+      requires(ImplType value) { value.IsNull(); };

   template <typename... ExtraArgs>

   static decltype(auto) ArgumentValue(v8::Isolate* isolate,

diff --git a/third_party/blink/renderer/bindings/core/v8/native_value_traits_buffer_sources.cc b/third_party/blink/renderer/bindings/core/v8/native_value_traits_buffer_sources.cc

index 508ea6d8eea48..18de71d84023f 100644

--- a/third_party/blink/renderer/bindings/core/v8/native_value_traits_buffer_sources.cc

+++ b/third_party/blink/renderer/bindings/core/v8/native_value_traits_buffer_sources.cc

@@ -7,6 +7,7 @@

 #include "third_party/blink/renderer/core/core_export.h"

 #include "third_party/blink/renderer/core/execution_context/execution_context.h"

 #include "third_party/blink/renderer/core/frame/web_feature.h"

+#include "third_party/blink/renderer/core/typed_arrays/flexible_array_buffer_view.h"

 #include "third_party/blink/renderer/core/typed_arrays/typed_flexible_array_buffer_view.h"

 namespace blink {

@@ -698,12 +699,11 @@ DOMArrayBufferBase* NativeValueTraits<

 // ArrayBufferView

 template <typename T>

-NotShared<T> NativeValueTraits<

-    NotShared<T>,

-    typename std::enable_if_t<std::is_base_of<DOMArrayBufferView, T>::value>>::

-    NativeValue(v8::Isolate* isolate,

-                v8::Local<v8::Value> value,

-                ExceptionState& exception_state) {

+  requires std::derived_from<T, DOMArrayBufferView>

+NotShared<T> NativeValueTraits<NotShared<T>>::NativeValue(

+    v8::Isolate* isolate,

+    v8::Local<v8::Value> value,

+    ExceptionState& exception_state) {

   return NativeValueImpl<

       RecipeTrait<NotShared<T>>, ToDOMViewType<T, kNotShared>,

       Nullablity::kIsNotNullable, BufferSizeCheck::kCheck,

@@ -712,13 +712,12 @@ NotShared<T> NativeValueTraits<

 }

 template <typename T>

-NotShared<T> NativeValueTraits<

-    NotShared<T>,

-    typename std::enable_if_t<std::is_base_of<DOMArrayBufferView, T>::value>>::

-    ArgumentValue(v8::Isolate* isolate,

-                  int argument_index,

-                  v8::Local<v8::Value> value,

-                  ExceptionState& exception_state) {

+  requires std::derived_from<T, DOMArrayBufferView>

+NotShared<T> NativeValueTraits<NotShared<T>>::ArgumentValue(

+    v8::Isolate* isolate,

+    int argument_index,

+    v8::Local<v8::Value> value,

+    ExceptionState& exception_state) {

   return ArgumentValueImpl<

       RecipeTrait<NotShared<T>>, ToDOMViewType<T, kNotShared>,

       Nullablity::kIsNotNullable, BufferSizeCheck::kCheck,

@@ -729,12 +728,11 @@ NotShared<T> NativeValueTraits<

 // [AllowShared] ArrayBufferView

 template <typename T>

-MaybeShared<T> NativeValueTraits<

-    MaybeShared<T>,

-    typename std::enable_if_t<std::is_base_of<DOMArrayBufferView, T>::value>>::

-    NativeValue(v8::Isolate* isolate,

-                v8::Local<v8::Value> value,

-                ExceptionState& exception_state) {

+  requires std::derived_from<T, DOMArrayBufferView>

+MaybeShared<T> NativeValueTraits<MaybeShared<T>>::NativeValue(

+    v8::Isolate* isolate,

+    v8::Local<v8::Value> value,

+    ExceptionState& exception_state) {

   return NativeValueImpl<RecipeTrait<MaybeShared<T>>,

                          ToDOMViewType<T, kMaybeShared>,

                          Nullablity::kIsNotNullable, BufferSizeCheck::kCheck,

@@ -743,13 +741,12 @@ MaybeShared<T> NativeValueTraits<

 }

 template <typename T>

-MaybeShared<T> NativeValueTraits<

-    MaybeShared<T>,

-    typename std::enable_if_t<std::is_base_of<DOMArrayBufferView, T>::value>>::

-    ArgumentValue(v8::Isolate* isolate,

-                  int argument_index,

-                  v8::Local<v8::Value> value,

-                  ExceptionState& exception_state) {

+  requires std::derived_from<T, DOMArrayBufferView>

+MaybeShared<T> NativeValueTraits<MaybeShared<T>>::ArgumentValue(

+    v8::Isolate* isolate,

+    int argument_index,

+    v8::Local<v8::Value> value,

+    ExceptionState& exception_state) {

   return ArgumentValueImpl<RecipeTrait<MaybeShared<T>>,

                            ToDOMViewType<T, kMaybeShared>,

                            Nullablity::kIsNotNullable, BufferSizeCheck::kCheck,

@@ -760,12 +757,12 @@ MaybeShared<T> NativeValueTraits<

 // [AllowShared, BufferSourceTypeNoSizeLimit] ArrayBufferView

 template <typename T>

-MaybeShared<T> NativeValueTraits<

-    IDLBufferSourceTypeNoSizeLimit<MaybeShared<T>>,

-    typename std::enable_if_t<std::is_base_of<DOMArrayBufferView, T>::value>>::

-    NativeValue(v8::Isolate* isolate,

-                v8::Local<v8::Value> value,

-                ExceptionState& exception_state) {

+  requires std::derived_from<T, DOMArrayBufferView>

+MaybeShared<T>

+NativeValueTraits<IDLBufferSourceTypeNoSizeLimit<MaybeShared<T>>>::NativeValue(

+    v8::Isolate* isolate,

+    v8::Local<v8::Value> value,

+    ExceptionState& exception_state) {

   return NativeValueImpl<

       RecipeTrait<MaybeShared<T>>, ToDOMViewType<T, kMaybeShared>,

       Nullablity::kIsNotNullable, BufferSizeCheck::kDoNotCheck,

@@ -774,13 +771,12 @@ MaybeShared<T> NativeValueTraits<

 }

 template <typename T>

-MaybeShared<T> NativeValueTraits<

-    IDLBufferSourceTypeNoSizeLimit<MaybeShared<T>>,

-    typename std::enable_if_t<std::is_base_of<DOMArrayBufferView, T>::value>>::

-    ArgumentValue(v8::Isolate* isolate,

-                  int argument_index,

-                  v8::Local<v8::Value> value,

-                  ExceptionState& exception_state) {

+  requires std::derived_from<T, DOMArrayBufferView>

+MaybeShared<T> NativeValueTraits

+    MaybeShared<T>>>::ArgumentValue(v8::Isolate* isolate,

+                                    int argument_index,

+                                    v8::Local<v8::Value> value,

+                                    ExceptionState& exception_state) {

   return ArgumentValueImpl<

       RecipeTrait<MaybeShared<T>>, ToDOMViewType<T, kMaybeShared>,

       Nullablity::kIsNotNullable, BufferSizeCheck::kDoNotCheck,

@@ -791,12 +787,11 @@ MaybeShared<T> NativeValueTraits<

 // Nullable ArrayBufferView

 template <typename T>

-NotShared<T> NativeValueTraits<

-    IDLNullable<NotShared<T>>,

-    typename std::enable_if_t<std::is_base_of<DOMArrayBufferView, T>::value>>::

-    NativeValue(v8::Isolate* isolate,

-                v8::Local<v8::Value> value,

-                ExceptionState& exception_state) {

+  requires std::derived_from<T, DOMArrayBufferView>

+NotShared<T> NativeValueTraits<IDLNullable<NotShared<T>>>::NativeValue(

+    v8::Isolate* isolate,

+    v8::Local<v8::Value> value,

+    ExceptionState& exception_state) {

   return NativeValueImpl<

       RecipeTrait<NotShared<T>>, ToDOMViewType<T, kNotShared>,

       Nullablity::kIsNullable, BufferSizeCheck::kCheck,

@@ -805,13 +800,12 @@ NotShared<T> NativeValueTraits<

 }

 template <typename T>

-NotShared<T> NativeValueTraits<

-    IDLNullable<NotShared<T>>,

-    typename std::enable_if_t<std::is_base_of<DOMArrayBufferView, T>::value>>::

-    ArgumentValue(v8::Isolate* isolate,

-                  int argument_index,

-                  v8::Local<v8::Value> value,

-                  ExceptionState& exception_state) {

+  requires std::derived_from<T, DOMArrayBufferView>

+NotShared<T> NativeValueTraits<IDLNullable<NotShared<T>>>::ArgumentValue(

+    v8::Isolate* isolate,

+    int argument_index,

+    v8::Local<v8::Value> value,

+    ExceptionState& exception_state) {

   return ArgumentValueImpl<

       RecipeTrait<NotShared<T>>, ToDOMViewType<T, kNotShared>,

       Nullablity::kIsNullable, BufferSizeCheck::kCheck,

@@ -822,12 +816,11 @@ NotShared<T> NativeValueTraits<

 // Nullable [AllowShared] ArrayBufferView

 template <typename T>

-MaybeShared<T> NativeValueTraits<

-    IDLNullable<MaybeShared<T>>,

-    typename std::enable_if_t<std::is_base_of<DOMArrayBufferView, T>::value>>::

-    NativeValue(v8::Isolate* isolate,

-                v8::Local<v8::Value> value,

-                ExceptionState& exception_state) {

+  requires std::derived_from<T, DOMArrayBufferView>

+MaybeShared<T> NativeValueTraits<IDLNullable<MaybeShared<T>>>::NativeValue(

+    v8::Isolate* isolate,

+    v8::Local<v8::Value> value,

+    ExceptionState& exception_state) {

   return NativeValueImpl<RecipeTrait<MaybeShared<T>>,

                          ToDOMViewType<T, kMaybeShared>,

                          Nullablity::kIsNullable, BufferSizeCheck::kCheck,

@@ -836,13 +829,12 @@ MaybeShared<T> NativeValueTraits<

 }

 template <typename T>

-MaybeShared<T> NativeValueTraits<

-    IDLNullable<MaybeShared<T>>,

-    typename std::enable_if_t<std::is_base_of<DOMArrayBufferView, T>::value>>::

-    ArgumentValue(v8::Isolate* isolate,

-                  int argument_index,

-                  v8::Local<v8::Value> value,

-                  ExceptionState& exception_state) {

+  requires std::derived_from<T, DOMArrayBufferView>

+MaybeShared<T> NativeValueTraits<IDLNullable<MaybeShared<T>>>::ArgumentValue(

+    v8::Isolate* isolate,

+    int argument_index,

+    v8::Local<v8::Value> value,

+    ExceptionState& exception_state) {

   return ArgumentValueImpl<RecipeTrait<MaybeShared<T>>,

                            ToDOMViewType<T, kMaybeShared>,

                            Nullablity::kIsNullable, BufferSizeCheck::kCheck,

@@ -853,9 +845,9 @@ MaybeShared<T> NativeValueTraits<

 // Nullable [AllowShared, BufferSourceTypeNoSizeLimit] ArrayBufferView

 template <typename T>

-MaybeShared<T> NativeValueTraits<

-    IDLNullable<IDLBufferSourceTypeNoSizeLimit<MaybeShared<T>>>,

-    typename std::enable_if_t<std::is_base_of<DOMArrayBufferView, T>::value>>::

+  requires std::derived_from<T, DOMArrayBufferView>

+MaybeShared<T>

+NativeValueTraits<IDLNullable<IDLBufferSourceTypeNoSizeLimit<MaybeShared<T>>>>::

     ArgumentValue(v8::Isolate* isolate,

                   int argument_index,

                   v8::Local<v8::Value> value,

@@ -870,13 +862,11 @@ MaybeShared<T> NativeValueTraits<

 // [AllowShared, FlexibleArrayBufferView] ArrayBufferView

 template <typename T>

-T NativeValueTraits

-                    typename std::enable_if_t<

-                        std::is_base_of<FlexibleArrayBufferView, T>::value>>::

-    ArgumentValue(v8::Isolate* isolate,

-                  int argument_index,

-                  v8::Local<v8::Value> value,

-                  ExceptionState& exception_state) {

+  requires std::derived_from<T, FlexibleArrayBufferView>

+T NativeValueTraits<T>::ArgumentValue(v8::Isolate* isolate,

+                                      int argument_index,

+                                      v8::Local<v8::Value> value,

+                                      ExceptionState& exception_state) {

   return ArgumentValueImpl<RecipeTrait<T>, ToFlexibleArrayBufferView,

                            Nullablity::kIsNotNullable, BufferSizeCheck::kCheck,

                            ResizableAllowance::kDisallowResizable,

@@ -888,13 +878,12 @@ T NativeValueTraits

 // ArrayBufferView

 template <typename T>

-T NativeValueTraits<IDLBufferSourceTypeNoSizeLimit<T>,

-                    typename std::enable_if_t<

-                        std::is_base_of<FlexibleArrayBufferView, T>::value>>::

-    ArgumentValue(v8::Isolate* isolate,

-                  int argument_index,

-                  v8::Local<v8::Value> value,

-                  ExceptionState& exception_state) {

+  requires std::derived_from<T, FlexibleArrayBufferView>

+T NativeValueTraits<IDLBufferSourceTypeNoSizeLimit<T>>::ArgumentValue(

+    v8::Isolate* isolate,

+    int argument_index,

+    v8::Local<v8::Value> value,

+    ExceptionState& exception_state) {

   return ArgumentValueImpl<

       RecipeTrait<T>, ToFlexibleArrayBufferView, Nullablity::kIsNotNullable,

       BufferSizeCheck::kDoNotCheck, ResizableAllowance::kDisallowResizable,

@@ -905,13 +894,12 @@ T NativeValueTraits<IDLBufferSourceTypeNoSizeLimit<T>,

 // Nullable [AllowShared, FlexibleArrayBufferView] ArrayBufferView

 template <typename T>

-T NativeValueTraits<IDLNullable<T>,

-                    typename std::enable_if_t<

-                        std::is_base_of<FlexibleArrayBufferView, T>::value>>::

-    ArgumentValue(v8::Isolate* isolate,

-                  int argument_index,

-                  v8::Local<v8::Value> value,

-                  ExceptionState& exception_state) {

+  requires std::derived_from<T, FlexibleArrayBufferView>

+T NativeValueTraits<IDLNullable<T>>::ArgumentValue(

+    v8::Isolate* isolate,

+    int argument_index,

+    v8::Local<v8::Value> value,

+    ExceptionState& exception_state) {

   return ArgumentValueImpl<RecipeTrait<T>, ToFlexibleArrayBufferView,

                            Nullablity::kIsNullable, BufferSizeCheck::kCheck,

                            ResizableAllowance::kDisallowResizable,

diff --git a/third_party/blink/renderer/bindings/core/v8/native_value_traits_impl.h b/third_party/blink/renderer/bindings/core/v8/native_value_traits_impl.h

index 899929dcf49f9..5011503dcf1c0 100644

--- a/third_party/blink/renderer/bindings/core/v8/native_value_traits_impl.h

+++ b/third_party/blink/renderer/bindings/core/v8/native_value_traits_impl.h

@@ -715,9 +718,8 @@ struct CORE_EXPORT NativeValueTraits<

 };

 template <typename T>

-struct NativeValueTraits<

-    T,

-    typename std::enable_if_t<std::is_base_of<DOMArrayBufferView, T>::value>> {

+  requires std::derived_from<T, DOMArrayBufferView>

+struct NativeValueTraits<T> {

   // NotShared<T> or MaybeShared<T> should be used instead.

   static T* NativeValue(v8::Isolate* isolate,

                         v8::Local<v8::Value> value,

@@ -729,9 +731,8 @@ struct NativeValueTraits<

 };

 template <typename T>

-struct NativeValueTraits<

-    IDLNullable<T>,

-    typename std::enable_if_t<std::is_base_of<DOMArrayBufferView, T>::value>> {

+  requires std::derived_from<T, DOMArrayBufferView>

+struct NativeValueTraits<IDLNullable<T>> {

   // NotShared<T> or MaybeShared<T> should be used instead.

   static T* NativeValue(v8::Isolate* isolate,

                         v8::Local<v8::Value> value,

@@ -743,9 +744,8 @@ struct NativeValueTraits<

 };

 template <typename T>

-struct NativeValueTraits<

-    NotShared<T>,

-    typename std::enable_if_t<std::is_base_of<DOMArrayBufferView, T>::value>>

+  requires std::derived_from<T, DOMArrayBufferView>

+struct NativeValueTraits<NotShared<T>>

     : public NativeValueTraitsBase<NotShared<T>> {

   static NotShared<T> NativeValue(v8::Isolate* isolate,

                                   v8::Local<v8::Value> value,

@@ -758,9 +758,8 @@ struct NativeValueTraits<

 };

 template <typename T>

-struct NativeValueTraits<

-    IDLNullable<NotShared<T>>,

-    typename std::enable_if_t<std::is_base_of<DOMArrayBufferView, T>::value>>

+  requires std::derived_from<T, DOMArrayBufferView>

+struct NativeValueTraits<IDLNullable<NotShared<T>>>

     : public NativeValueTraitsBase<NotShared<T>> {

   static NotShared<T> NativeValue(v8::Isolate* isolate,

                                   v8::Local<v8::Value> value,

@@ -773,9 +772,8 @@ struct NativeValueTraits<

 };

 template <typename T>

-struct NativeValueTraits<

-    MaybeShared<T>,

-    typename std::enable_if_t<std::is_base_of<DOMArrayBufferView, T>::value>>

+  requires std::derived_from<T, DOMArrayBufferView>

+struct NativeValueTraits<MaybeShared<T>>

     : public NativeValueTraitsBase<MaybeShared<T>> {

   static MaybeShared<T> NativeValue(v8::Isolate* isolate,

                                     v8::Local<v8::Value> value,

@@ -788,9 +786,8 @@ struct NativeValueTraits<

 };

 template <typename T>

-struct NativeValueTraits<

-    IDLBufferSourceTypeNoSizeLimit<MaybeShared<T>>,

-    typename std::enable_if_t<std::is_base_of<DOMArrayBufferView, T>::value>>

+  requires std::derived_from<T, DOMArrayBufferView>

+struct NativeValueTraits<IDLBufferSourceTypeNoSizeLimit<MaybeShared<T>>>

     : public NativeValueTraitsBase<MaybeShared<T>> {

   // FlexibleArrayBufferView uses this in its implementation, so we cannot

   // delete it.

@@ -805,9 +802,8 @@ struct NativeValueTraits<

 };

 template <typename T>

-struct NativeValueTraits<

-    IDLNullable<MaybeShared<T>>,

-    typename std::enable_if_t<std::is_base_of<DOMArrayBufferView, T>::value>>

+  requires std::derived_from<T, DOMArrayBufferView>

+struct NativeValueTraits<IDLNullable<MaybeShared<T>>>

     : public NativeValueTraitsBase<MaybeShared<T>> {

   static MaybeShared<T> NativeValue(v8::Isolate* isolate,

                                     v8::Local<v8::Value> value,

@@ -820,9 +816,9 @@ struct NativeValueTraits<

 };

 template <typename T>

+  requires std::derived_from<T, DOMArrayBufferView>

 struct NativeValueTraits<

-    IDLNullable<IDLBufferSourceTypeNoSizeLimit<MaybeShared<T>>>,

-    typename std::enable_if_t<std::is_base_of<DOMArrayBufferView, T>::value>>

+    IDLNullable<IDLBufferSourceTypeNoSizeLimit<MaybeShared<T>>>>

     : public NativeValueTraitsBase<MaybeShared<T>> {

   // BufferSourceTypeNoSizeLimit must be used only as arguments.

   static MaybeShared<T> NativeValue(v8::Isolate* isolate,

@@ -836,11 +832,8 @@ struct NativeValueTraits<

 };

 template <typename T>

-struct NativeValueTraits<

-    T,

-    typename std::enable_if_t<

-        std::is_base_of<FlexibleArrayBufferView, T>::value>>

-    : public NativeValueTraitsBase<T> {

+  requires std::derived_from<T, FlexibleArrayBufferView>

+struct NativeValueTraits<T> : public NativeValueTraitsBase<T> {

   // FlexibleArrayBufferView must be used only as arguments.

   static T NativeValue(v8::Isolate* isolate,

                        v8::Local<v8::Value> value,

@@ -853,10 +846,8 @@ struct NativeValueTraits<

 };

 template <typename T>

-struct NativeValueTraits<

-    IDLBufferSourceTypeNoSizeLimit<T>,

-    typename std::enable_if_t<

-        std::is_base_of<FlexibleArrayBufferView, T>::value>>

+  requires std::derived_from<T, FlexibleArrayBufferView>

+struct NativeValueTraits<IDLBufferSourceTypeNoSizeLimit<T>>

     : public NativeValueTraitsBase<T> {

   // BufferSourceTypeNoSizeLimit and FlexibleArrayBufferView must be used only

   // as arguments.

@@ -871,11 +862,8 @@ struct NativeValueTraits<

 };

 template <typename T>

-struct NativeValueTraits<

-    IDLNullable<T>,

-    typename std::enable_if_t<

-        std::is_base_of<FlexibleArrayBufferView, T>::value>>

-    : public NativeValueTraitsBase<T> {

+  requires std::derived_from<T, FlexibleArrayBufferView>

+struct NativeValueTraits<IDLNullable<T>> : public NativeValueTraitsBase<T> {

   // FlexibleArrayBufferView must be used only as arguments.

   static T NativeValue(v8::Isolate* isolate,

                        v8::Local<v8::Value> value,

@@ -1134,9 +1122,8 @@ NativeValueTraits<IDLSequence<T>>::NativeValue(

 }

 template <typename T>

-struct NativeValueTraits<IDLNullable<IDLSequence<T>>,

-                         typename std::enable_if_t<

-                             NativeValueTraits<IDLSequence<T>>::has_null_value>>

+  requires NativeValueTraits<IDLSequence<T>>::has_null_value

+struct NativeValueTraits<IDLNullable<IDLSequence<T>>>

     : public NativeValueTraitsBase<HeapVector<AddMemberIfNeeded<T>>*> {

   using ImplType = typename NativeValueTraits<IDLSequence<T>>::ImplType*;

@@ -1203,9 +1190,8 @@ struct NativeValueTraits<IDLArray<T>>

     : public NativeValueTraits<IDLSequence<T>> {};

 template <typename T>

-struct NativeValueTraits<IDLNullable<IDLArray<T>>,

-                         typename std::enable_if_t<

-                             NativeValueTraits<IDLSequence<T>>::has_null_value>>

+  requires NativeValueTraits<IDLSequence<T>>::has_null_value

+struct NativeValueTraits<IDLNullable<IDLArray<T>>>

     : public NativeValueTraits<IDLNullable<IDLSequence<T>>> {};

 // Record types

@@ -1335,10 +1321,8 @@ struct NativeValueTraits<IDLRecord<K, V>>

 // Callback function types

 template <typename T>

-struct NativeValueTraits<

-    T,

-    typename std::enable_if_t<std::is_base_of<CallbackFunctionBase, T>::value>>

-    : public NativeValueTraitsBase<T*> {

+  requires std::derived_from<T, CallbackFunctionBase>

+struct NativeValueTraits<T> : public NativeValueTraitsBase<T*> {

   static T* NativeValue(v8::Isolate* isolate,

                         v8::Local<v8::Value> value,

                         ExceptionState& exception_state) {

@@ -1361,9 +1345,8 @@ struct NativeValueTraits<

 };

 template <typename T>

-struct NativeValueTraits<

-    IDLNullable<T>,

-    typename std::enable_if_t<std::is_base_of<CallbackFunctionBase, T>::value>>

+  requires std::derived_from<T, CallbackFunctionBase>

+struct NativeValueTraits<IDLNullable<T>>

     : public NativeValueTraitsBase<IDLNullable<T>> {

   static T* NativeValue(v8::Isolate* isolate,

                         v8::Local<v8::Value> value,

@@ -1392,10 +1375,8 @@ struct NativeValueTraits<

 // Callback interface types

 template <typename T>

-struct NativeValueTraits<

-    T,

-    typename std::enable_if_t<std::is_base_of<CallbackInterfaceBase, T>::value>>

-    : public NativeValueTraitsBase<T*> {

+  requires std::derived_from<T, CallbackInterfaceBase>

+struct NativeValueTraits<T> : public NativeValueTraitsBase<T*> {

   static T* NativeValue(v8::Isolate* isolate,

                         v8::Local<v8::Value> value,

                         ExceptionState& exception_state) {

@@ -1418,9 +1399,8 @@ struct NativeValueTraits<

 };

 template <typename T>

-struct NativeValueTraits<

-    IDLNullable<T>,

-    typename std::enable_if_t<std::is_base_of<CallbackInterfaceBase, T>::value>>

+  requires std::derived_from<T, CallbackInterfaceBase>

+struct NativeValueTraits<IDLNullable<T>>

     : public NativeValueTraitsBase<IDLNullable<T>> {

   static T* NativeValue(v8::Isolate* isolate,

                         v8::Local<v8::Value> value,

@@ -1449,11 +1429,8 @@ struct NativeValueTraits<

 // Dictionary types

 template <typename T>

-struct NativeValueTraits<

-    T,

-    typename std::enable_if_t<

-        std::is_base_of<bindings::DictionaryBase, T>::value>>

-    : public NativeValueTraitsBase<T*> {

+  requires std::derived_from<T, bindings::DictionaryBase>

+struct NativeValueTraits<T> : public NativeValueTraitsBase<T*> {

   static T* NativeValue(v8::Isolate* isolate,

                         v8::Local<v8::Value> value,

                         ExceptionState& exception_state) {

@@ -1464,14 +1441,11 @@ struct NativeValueTraits<

 // We don't support nullable dictionary types in general since it's quite

 // confusing and often misused.

 template <typename T>

-struct NativeValueTraits<

-    IDLNullable<T>,

-    typename std::enable_if_t<

-        std::is_base_of<bindings::DictionaryBase, T>::value &&

-        (std::is_same<T, GPUColorTargetState>::value ||

-         std::is_same<T, GPURenderPassColorAttachment>::value ||

-         std::is_same<T, GPUVertexBufferLayout>::value)>>

-    : public NativeValueTraitsBase<T*> {

+  requires std::derived_from<T, bindings::DictionaryBase> &&

+           (std::same_as<T, GPUColorTargetState> ||

+            std::same_as<T, GPURenderPassColorAttachment> ||

+            std::same_as<T, GPUVertexBufferLayout>)

+struct NativeValueTraits<IDLNullable<T>> : public NativeValueTraitsBase<T*> {

   static T* NativeValue(v8::Isolate* isolate,

                         v8::Local<v8::Value> value,

                         ExceptionState& exception_state) {

@@ -1483,11 +1457,8 @@ struct NativeValueTraits<

 // Enumeration types

 template <typename T>

-struct NativeValueTraits<

-    T,

-    typename std::enable_if_t<

-        std::is_base_of<bindings::EnumerationBase, T>::value>>

-    : public NativeValueTraitsBase<T> {

+  requires std::derived_from<T, bindings::EnumerationBase>

+struct NativeValueTraits<T> : public NativeValueTraitsBase<T> {

   static T NativeValue(v8::Isolate* isolate,

                        v8::Local<v8::Value> value,

                        ExceptionState& exception_state) {

@@ -1497,10 +1468,8 @@ struct NativeValueTraits<

 // Interface types

 template <typename T>

-struct NativeValueTraits<

-    T,

-    typename std::enable_if_t<std::is_base_of<ScriptWrappable, T>::value>>

-    : public NativeValueTraitsBase<T*> {

+  requires std::derived_from<T, ScriptWrappable>

+struct NativeValueTraits<T> : public NativeValueTraitsBase<T*> {

   static inline T* NativeValue(v8::Isolate* isolate,

                                v8::Local<v8::Value> value,

                                ExceptionState& exception_state) {

@@ -1528,9 +1497,8 @@ struct NativeValueTraits<

 };

 template <typename T>

-struct NativeValueTraits<

-    IDLNullable<T>,

-    typename std::enable_if_t<std::is_base_of<ScriptWrappable, T>::value>>

+  requires std::derived_from<T, ScriptWrappable>

+struct NativeValueTraits<IDLNullable<T>>

     : public NativeValueTraitsBase<IDLNullable<T>> {

   static inline T* NativeValue(v8::Isolate* isolate,

                                v8::Local<v8::Value> value,

@@ -1565,10 +1533,8 @@ struct NativeValueTraits<

 };

 template <typename T>

-struct NativeValueTraits<

-    T,

-    typename std::enable_if_t<std::is_base_of<bindings::UnionBase, T>::value>>

-    : public NativeValueTraitsBase<T*> {

+  requires std::derived_from<T, bindings::UnionBase>

+struct NativeValueTraits<T> : public NativeValueTraitsBase<T*> {

   static T* NativeValue(v8::Isolate* isolate,

                         v8::Local<v8::Value> value,

                         ExceptionState& exception_state) {

@@ -1584,10 +1550,8 @@ struct NativeValueTraits<

 };

 template <typename T>

-struct NativeValueTraits<

-    IDLNullable<T>,

-    typename std::enable_if_t<std::is_base_of<bindings::UnionBase, T>::value>>

-    : public NativeValueTraitsBase<T*> {

+  requires std::derived_from<T, bindings::UnionBase>

+struct NativeValueTraits<IDLNullable<T>> : public NativeValueTraitsBase<T*> {

   static T* NativeValue(v8::Isolate* isolate,

                         v8::Local<v8::Value> value,

                         ExceptionState& exception_state) {

@@ -1608,9 +1572,8 @@ struct NativeValueTraits<

 // Nullable types

 template <typename InnerType>

-struct NativeValueTraits<

-    IDLNullable<InnerType>,

-    typename std::enable_if_t::has_null_value>>

+  requires(!NativeValueTraits<InnerType>::has_null_value)

+struct NativeValueTraits<IDLNullable<InnerType>>

     : public NativeValueTraitsBase<IDLNullable<InnerType>> {

   // https://webidl.spec.whatwg.org/#es-nullable-type

   using ImplType =

@@ -1642,9 +1605,8 @@ struct NativeValueTraits<IDLNullable<IDLNullable<T>>>;

 // Optional types

 template <typename T>

-struct NativeValueTraits<IDLOptional<T>,

-                         typename std::enable_if_t

-                             typename NativeValueTraits<T>::ImplType>::value>>

+  requires std::is_arithmetic_v<typename NativeValueTraits<T>::ImplType>

+struct NativeValueTraits<IDLOptional<T>>