Update some underscore public API doc

Sources/OpenSwiftUI/Core/Graph/Graph.swift

@@ -5,4 +5,5 @@
 //  Audited for RELEASE_2021
 //  Status: Complete
 
+/// A transient reference to a view graph.
 public struct _Graph {}

Sources/OpenSwiftUI/Core/Graph/GraphInputsModifier.swift

@@ -5,6 +5,7 @@
 //  Audited for RELEASE_2021
 //  Status: Complete
 
+/// Protocol for modifiers that only modify their children's inputs.
 public protocol _GraphInputsModifier {
     static func _makeInputs(modifier: _GraphValue<Self>, inputs: inout _GraphInputs)
 }

Sources/OpenSwiftUI/Core/Graph/GraphValue.swift

@@ -7,6 +7,9 @@
 
 internal import OpenGraphShims
 
+/// A transient reference to a value in the view hierarchy's dataflow
+/// graph. "Transient" means that these values must never be stored,
+/// only passed around while initializing views.
 public struct _GraphValue<Value>: Equatable {
     var value: Attribute<Value>
 
@@ -26,6 +29,8 @@ public struct _GraphValue<Value>: Equatable {
         _GraphValue<V>(value.unsafeBitCast(to: type))
     }
 
+    /// Returns the value created by fetching the property at `keyPath`
+    /// of `self`.
     public subscript<Member>(keyPath: KeyPath<Value, Member>) -> _GraphValue<Member> {
         _GraphValue<Member>(value[keyPath: keyPath])
     }

Sources/OpenSwiftUI/Core/Modifier/ModifiedContent.swift

@@ -111,6 +111,8 @@ extension ModifiedContent: ViewModifier where Content: ViewModifier, Modifier: V
 }
 
 extension ViewModifier {
+    /// Returns a new modifier that is the result of concatenating
+    /// `self` with `modifier`.
     @inlinable
     @inline(__always)
     public func concat<T>(_ modifier: T) -> ModifiedContent<Self, T> {

Sources/OpenSwiftUI/Core/Modifier/ViewModifier/ViewModifier.swift

@@ -49,8 +49,10 @@
 ///  caption in blue text surrounded by a rounded
 ///  rectangle.](OpenSwiftUI-View-ViewModifier.png)
 public protocol ViewModifier {
+    /// The type of view representing the body.
     associatedtype Body: View
 
+    /// Makes a new view using the view modifier and inputs that you provide.
     static func _makeView(
         modifier: _GraphValue<Self>,
         inputs: _ViewInputs,
@@ -63,11 +65,14 @@ public protocol ViewModifier {
         body: @escaping (_Graph, _ViewListInputs) -> _ViewListOutputs
     ) -> _ViewListOutputs
 
+    /// The number of views that `_makeViewList()` would produce, or
+    /// nil if unknown.
     static func _viewListCount(
         inputs: _ViewListCountInputs,
         body: (_ViewListCountInputs) -> Int?
     ) -> Int?
 
+    /// The content view type passed to `body()`.
     typealias Content = _ViewModifier_Content<Self>
 
     /// Gets the current body of the caller.

Sources/OpenSwiftUI/Core/View/ConditionalContent.swift

@@ -8,6 +8,7 @@
 
 internal import OpenGraphShims
 
+/// View content that shows one of two possible children.
 @frozen
 public struct _ConditionalContent<TrueContent, FalseContent> {
     @usableFromInline

Sources/OpenSwiftUI/Core/View/View.swift

@@ -76,6 +76,10 @@ public protocol View {
 }
 
 extension View {
+    /// Instantiates the view using `view` as its source value, and
+    /// `inputs` as its input values. Returns the view's output values.
+    /// This should never be called directly, instead use the
+    /// makeDebuggableView() shim function.
     public static func _makeView(view: _GraphValue<Self>, inputs: _ViewInputs) -> _ViewOutputs {
         makeView(view: view, inputs: inputs)
     }

Sources/OpenSwiftUI/Core/View/View/ViewInputs.swift

@@ -7,6 +7,10 @@
 
 internal import OpenGraphShims
 
+/// The input (aka inherited) attributes supplied to each view. Most
+/// view types will only actually wire a small number of these into
+/// their node. Doesn't include the view itself, which is passed
+/// separately.
 public struct _ViewInputs {
     private var base: _GraphInputs
     var preferences: PreferencesInputs

Sources/OpenSwiftUI/Core/View/View/ViewOutputs.swift

@@ -1,5 +1,6 @@
 internal import OpenGraphShims
 
+/// The output (aka synthesized) attributes returned by each view.
 public struct _ViewOutputs {
     private var preferences = PreferencesOutputs()
     @OptionalAttribute var layoutComputer: LayoutComputer?

Sources/OpenSwiftUI/Core/View/ViewList/ViewListCountInputs.swift

@@ -5,6 +5,7 @@
 //  Audited for RELEASE_2021
 //  Status: WIP
 
+/// Input values to `View._viewListCount()`.
 public struct _ViewListCountInputs {
     var customInputs : PropertyList
     var options : _ViewListInputs.Options

Sources/OpenSwiftUI/Core/View/ViewList/ViewListInputs.swift

@@ -7,6 +7,7 @@
 
 internal import OpenGraphShims
 
+/// Input values to `View._makeViewList()`.
 public struct _ViewListInputs {
     private var base: _GraphInputs
     var implicitID: Int

Sources/OpenSwiftUI/Core/View/ViewList/ViewListOutputs.swift

@@ -7,6 +7,7 @@
 
 internal import OpenGraphShims
 
+/// Output values from `View._makeViewList()`.
 public struct _ViewListOutputs {
     var views: Views
     var nextImplicitID: Int

Sources/OpenSwiftUI/Data/Model/DynamicProperty/DynamicProperty.swift

@@ -14,6 +14,8 @@ internal import OpenGraphShims
 /// The view gives values to these properties prior to recomputing the view's
 /// ``View/body-swift.property``.
 public protocol DynamicProperty {
+    /// Creates an instance of the dynamic `View` property
+    /// represented by `self`.
     static func _makeProperty<Value>(
         in buffer: inout _DynamicPropertyBuffer,
         container: _GraphValue<Value>,

Sources/OpenSwiftUI/View/Debug/ChangedBodyProperty.swift

@@ -12,12 +12,29 @@ import Foundation
 // MARK: - printChanges
 
 extension View {
+    /// When called within an invocation of `body` of a view of this
+    /// type, prints the names of the changed dynamic properties that
+    /// caused the result of `body` to need to be refreshed. As well as
+    /// the physical property names, "@self" is used to mark that the
+    /// view value itself has changed, and "@identity" to mark that the
+    /// identity of the view has changed (i.e. that the persistent data
+    /// associated with the view has been recycled for a new instance
+    /// of the same type).
     public static func _printChanges() {
         printChangedBodyProperties(of: Self.self)
     }
 }
 
 extension ViewModifier {
+    /// When called within an invocation of `body()` of a view modifier
+    /// of this type, prints the names of the changed dynamic
+    /// properties that caused the result of `body()` to need to be
+    /// refreshed. As well as the physical property names, "@self" is
+    /// used to mark that the modifier value itself has changed, and
+    /// "@identity" to mark that the identity of the modifier has
+    /// changed (i.e. that the persistent data associated with the
+    /// modifier has been recycled for a new instance of the same
+    /// type).
     public static func _printChanges() {
         printChangedBodyProperties(of: Self.self)
     }
@@ -58,12 +75,45 @@ extension OSLog {
 #endif
 
 extension View {
+    /// When called within an invocation of `body` of a view of this type, logs
+    /// the names of the changed dynamic properties that caused the result of
+    /// `body` to need to be refreshed.
+    ///
+    ///     var body: some View {
+    ///         let _ = Self._logChanges()
+    ///         ... view content ...
+    ///     }
+    ///
+    /// As well as the physical property names, "@self" is used to mark that the
+    /// view value itself has changed, and "@identity" to mark that the identity
+    /// of the view has changed (i.e. that the persistent data associated with
+    /// the view has been recycled for a new instance of the same type).
+    ///
+    /// The information is logged at the info level to the "org.OpenSwiftUIProject.OpenSwiftUI"
+    /// subsystem with the category "Changed Body Properties".
     public static func _logChanges() {
         logChangedBodyProperties(of: Self.self)
     }
 }
 
 extension ViewModifier {
+    /// When called within an invocation of `body` of a view modifier of this
+    /// type, logs the names of the changed dynamic properties that caused the
+    /// result of `body` to need to be refreshed.
+    ///
+    ///     func body(content: Self.Content): Self.Body {
+    ///         let _ = Self._logChanges()
+    ///         ... view modifier content ...
+    ///     }
+    ///
+    /// As well as the physical property names, "@self" is used to mark that the
+    /// modifier value itself has changed, and "@identity" to mark that the
+    /// identity of the modifier has changed (i.e. that the persistent data
+    /// associated with the modifier has been recycled for a new instance of the
+    /// same type).
+    ///
+    /// The information is logged at the info level to the "org.OpenSwiftUIProject.OpenSwiftUI"
+    /// subsystem with the category "Changed Body Properties".
     public static func _logChanges() {
         logChangedBodyProperties(of: Self.self)
     }