plugin_group! macro

crates/bevy_a11y/src/lib.rs

@@ -103,6 +103,7 @@ pub enum AccessibilitySystem {
 }
 
 /// Plugin managing non-GUI aspects of integrating with accessibility APIs.
+#[derive(Default)]
 pub struct AccessibilityPlugin;
 
 impl Plugin for AccessibilityPlugin {

crates/bevy_app/src/plugin_group.rs

@@ -2,6 +2,133 @@ use crate::{App, AppError, Plugin};
 use bevy_utils::{tracing::debug, tracing::warn, TypeIdMap};
 use std::any::TypeId;
 
+/// A macro for generating a well-documented [`PluginGroup`] from a list of [`Plugin`] paths.
+///
+/// Every plugin must implement the [`Default`] trait.
+///
+/// # Example
+///
+/// ```
+/// # use bevy_app::*;
+/// # mod velocity {
+/// #   use bevy_app::*;
+/// #   #[derive(Default)] pub struct VelocityPlugin;
+/// #   impl Plugin for VelocityPlugin { fn build(&self, _: &mut App) {} }
+/// # }
+/// # mod collision { pub mod capsule {
+/// #   use bevy_app::*;
+/// #   #[derive(Default)] pub struct CapsuleCollisionPlugin;
+/// #   impl Plugin for CapsuleCollisionPlugin { fn build(&self, _: &mut App) {} }
+/// # } }
+/// # #[derive(Default)] pub struct TickratePlugin;
+/// # impl Plugin for TickratePlugin { fn build(&self, _: &mut App) {} }
+/// # mod features {
+/// #   use bevy_app::*;
+/// #   #[derive(Default)] pub struct ForcePlugin;
+/// #   impl Plugin for ForcePlugin { fn build(&self, _: &mut App) {} }
+/// # }
+/// # mod web {
+/// #   use bevy_app::*;
+/// #   #[derive(Default)] pub struct WebCompatibilityPlugin;
+/// #   impl Plugin for WebCompatibilityPlugin { fn build(&self, _: &mut App) {} }
+/// # }
+/// # mod internal {
+/// #   use bevy_app::*;
+/// #   #[derive(Default)] pub struct InternalPlugin;
+/// #   impl Plugin for InternalPlugin { fn build(&self, _: &mut App) {} }
+/// # }
+/// plugin_group! {
+///     PhysicsPlugins {
+///         // Due to local ambiguity issues, you have to
+///         // use a colon before the plugin's name.
+///         :TickratePlugin,
+///         // Due to local ambiguity issues, you have to
+///         // use 3 colons for the last part of the path.
+///         collision::capsule:::CapsuleCollisionPlugin,
+///         velocity:::VelocityPlugin,
+///         // Add a documented feature restriction.
+///         #[cfg(feature = "external_forces")]
+///         features:::ForcePlugin,
+///         // You can add any attribute you want like this, but it won't be documented.
+///         #[custom(cfg(target_arch = "wasm32"))]
+///         web:::WebCompatibilityPlugin,
+///         // You can hide plugins from documentation.
+///         // NOTE: Due to macro limitations, you can only use
+///         //       #[doc(hidden)] for plugins at the bottom of the macro.
+///         #[doc(hidden)]
+///         internal:::InternalPlugin
+///     }
+/// }
+/// ```
+#[macro_export]
+macro_rules! plugin_group {
+    {
+        $(#[$group_meta:meta])*
+        $group:ident {
+            $(
+                $(#[cfg(feature = $plugin_feature:literal)])?
+                $(#[custom($plugin_meta:meta)])*
+                $($plugin_path:ident::)* : $plugin_name:ident
+            ),*
+            $(
+                $(,)?$(
+                    #[doc(hidden)]
+                    $(#[cfg(feature = $hidden_plugin_feature:literal)])?
+                    $(#[custom($hidden_plugin_meta:meta)])*
+                    $($hidden_plugin_path:ident::)* : $hidden_plugin_name:ident
+                ),+
+            )?
+
+            $(,)?
+        }
+        $($(#[doc = $post_doc:literal])+)?
+    } => {
+        $(#[$group_meta])*
+        ///
+        $(#[doc = concat!(
+            "* [`", stringify!($plugin_name), "`](" $(, stringify!($plugin_path), "::")*, stringify!($plugin_name), ")"
+            $(, " - with feature `", $plugin_feature, "`")?
+        )])*
+        $(
+            ///
+            $(#[doc = $post_doc])+
+        )?
+        pub struct $group;
+        impl $crate::PluginGroup for $group {
+            fn build(self) -> $crate::PluginGroupBuilder {
+                let mut group = $crate::PluginGroupBuilder::start::<Self>();
+
+                $(
+                    $(#[cfg(feature = $plugin_feature)])?
+                    $(#[$plugin_meta])*
+                    {
+                        const _: () = {
+                            const fn check_default<T: Default>() {}
+                            check_default::<$($plugin_path::)*$plugin_name>();
+                        };
+
+                        group = group.add(<$($plugin_path::)*$plugin_name>::default());
+                    }
+                )*
+                $($(
+                    $(#[cfg(feature = $hidden_plugin_feature)])?
+                    $(#[$hidden_plugin_meta])*
+                    {
+                        const _: () = {
+                            const fn check_default<T: Default>() {}
+                            check_default::<$($hidden_plugin_path::)*$hidden_plugin_name>();
+                        };
+
+                        group = group.add(<$($hidden_plugin_path::)*$hidden_plugin_name>::default());
+                    }
+                )+)?
+
+                group
+            }
+        }
+    };
+}
+
 /// Combines multiple [`Plugin`]s into a single unit.
 pub trait PluginGroup: Sized {
     /// Configures the [`Plugin`]s that are to be added.

crates/bevy_gizmos/src/lib.rs

@@ -111,6 +111,7 @@ const LINE_JOINT_SHADER_HANDLE: Handle<Shader> = Handle::weak_from_u128(11627807
 /// A [`Plugin`] that provides an immediate mode drawing api for visual debugging.
 ///
 /// Requires to be loaded after [`PbrPlugin`](bevy_pbr::PbrPlugin) or [`SpritePlugin`](bevy_sprite::SpritePlugin).
+#[derive(Default)]
 pub struct GizmoPlugin;
 
 impl Plugin for GizmoPlugin {