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<IDLBufferSourceTypeNoSizeLimit<
+    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<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<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<T,
 // 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<!NativeValueTraits<InnerType>::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<std::is_arithmetic<
-                             typename NativeValueTraits<T>::ImplType>::value>>
+  requires std::is_arithmetic_v<typename NativeValueTraits<T>::ImplType>
+struct NativeValueTraits<IDLOptional<T>>
     : public NativeValueTraitsBase<typename NativeValueTraits<T>::ImplType> {
   using ImplType = typename NativeValueTraits<T>::ImplType;
 
@@ -1666,9 +1628,8 @@ struct NativeValueTraits<IDLOptional<T>,
 };
 
 template <typename T>
-struct NativeValueTraits<IDLOptional<T>,
-                         typename std::enable_if_t<std::is_pointer<
-                             typename NativeValueTraits<T>::ImplType>::value>>
+  requires std::is_pointer_v<typename NativeValueTraits<T>::ImplType>
+struct NativeValueTraits<IDLOptional<T>>
     : public NativeValueTraitsBase<typename NativeValueTraits<T>::ImplType> {
   using ImplType = typename NativeValueTraits<T>::ImplType;