feat: add default_plugin feature

.github/workflows/ci.yaml

@@ -20,7 +20,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        feature-set: [ default, inventory, compat_generics_angles ]
+        feature-set: [ default, inventory, compat_generics_angles, default_plugin ]
     steps:
       - name: Checkout code
         uses: actions/checkout@v3
@@ -85,7 +85,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        feature-set: [ default, inventory ]
+        feature-set: [ default, inventory, default_plugin ]
     steps:
       - name: Checkout code
         uses: actions/checkout@v3

CHANGELOG.md

@@ -165,4 +165,5 @@
 - Allow action macros on `use` statements; each imported name becomes its own entry (no `*`, `self`, or `_`).
 - Add `pipe_in` for `auto_add_system`/`auto_system` to build system pipelines.
 - Accept `generics = <...>` as shorthand for `generics(...)` in attributes (feature: `compat_generics_angles`).
-  - This feature will eventually be removed unless a petition is opened.
+  - This feature will eventually be removed unless a petition is opened.
+- Add optional `default_plugin` feature to allow omitting `plugin = ...` when a default plugin is set via `#[auto_plugin(default_plugin)]`.

Cargo.toml

@@ -20,6 +20,10 @@ compat_generics_angles = [
     "bevy_auto_plugin_proc_macros/compat_generics_angles",
     "bevy_auto_plugin_shared/compat_generics_angles",
 ]
+default_plugin = [
+    "bevy_auto_plugin_proc_macros/default_plugin",
+    "bevy_auto_plugin_shared/default_plugin",
+]
 web = [
     "bevy_auto_plugin_shared/web",
 ]

README.md

@@ -201,6 +201,7 @@ fn plugin(app: &mut App) {
 ```
 
 There is `auto_plugin` arguments if your plugin has generics.
+Optional: enable feature `default_plugin` and add `#[auto_plugin(default_plugin)]` to allow `auto_*` macros to omit `plugin = ...`.
 
 See [tests](tests/e2e) for other examples
 

crates/bevy_auto_plugin_proc_macros/Cargo.toml

@@ -18,6 +18,7 @@ inventory = ["bevy_auto_plugin_shared/inventory"]
 debug_log_plugin_registry = ["bevy_auto_plugin_shared/debug_log_plugin_registry"]
 log_plugin_build = ["bevy_auto_plugin_shared/log_plugin_build"]
 compat_generics_angles = ["bevy_auto_plugin_shared/compat_generics_angles"]
+default_plugin = ["bevy_auto_plugin_shared/default_plugin"]
 
 [dependencies]
 bevy_auto_plugin_shared = { workspace = true }

crates/bevy_auto_plugin_shared/Cargo.toml

@@ -15,6 +15,7 @@ inventory = []
 debug_log_plugin_registry = ["log"]
 log_plugin_build = ["log"]
 compat_generics_angles = []
+default_plugin = []
 web = [
     "bevy_app/web"
 ]

crates/bevy_auto_plugin_shared/src/__private/expand/derive/auto_plugin.rs

@@ -76,6 +76,25 @@ pub fn expand_derive_auto_plugin(input: MacroStream) -> MacroStream {
         });
     }
 
+    #[cfg(feature = "default_plugin")]
+    if params.auto_plugin.default_plugin.is_present() {
+        if !params.generics.params.is_empty() {
+            compile_warnings.extend(
+                syn::Error::new(
+                    params.auto_plugin.default_plugin.span(),
+                    "`default_plugin` is not supported for generic plugins; use a concrete wrapper type",
+                )
+                .to_compile_error(),
+            );
+        } else {
+            output.extend(quote! {
+                #[doc(hidden)]
+                #[allow(dead_code)]
+                type __bevy_auto_plugin_default_plugin = #ident;
+            });
+        }
+    }
+
     quote! {
         #compile_warnings
         #output

crates/bevy_auto_plugin_shared/src/macro_api/attributes/auto_plugin.rs

@@ -22,6 +22,8 @@ pub struct AutoPluginStructOrEnumArgs {
     #[darling(multiple)]
     pub generics: Vec<TypeList>,
     pub impl_plugin_trait: Flag,
+    #[cfg(feature = "default_plugin")]
+    pub default_plugin: Flag,
     #[deprecated(
         since = "0.8.0",
         note = "always implemented - remove `impl_generic_auto_plugin_trait`"

crates/bevy_auto_plugin_shared/src/macro_api/composed.rs

@@ -55,6 +55,8 @@ where
         let generics_keys: HashSet<&str> = MGenerics::keys().iter().copied().collect();
 
         let mut plugin_bucket = Vec::<NestedMeta>::new();
+        #[cfg(feature = "default_plugin")]
+        let mut has_plugin_key = false;
         let mut generics_bucket = Vec::<NestedMeta>::new();
         let mut base_bucket = Vec::<NestedMeta>::new();
 
@@ -73,6 +75,10 @@ where
             };
 
             let routed = if let Some(ref k) = key_opt {
+                #[cfg(feature = "default_plugin")]
+                if k == "plugin" {
+                    has_plugin_key = true;
+                }
                 if plugin_keys.contains(k.as_str()) {
                     plugin_bucket.push(nm.clone());
                     true
@@ -91,6 +97,14 @@ where
             }
         }
 
+        #[cfg(feature = "default_plugin")]
+        if !has_plugin_key && plugin_keys.contains("plugin") {
+            plugin_bucket.insert(
+                0,
+                NestedMeta::Meta(parse_quote!(plugin = __bevy_auto_plugin_default_plugin)),
+            );
+        }
+
         // Parse each bucket
         let base = CBase::from_list(&base_bucket)?;
         let plugin = MPlugin::from_list(&plugin_bucket)?;

docs/derives/AutoPlugin.md

@@ -3,6 +3,7 @@ events, resources, and systems.
 
 # Parameters
 - `impl_plugin_trait` - Optional. When present, it automatically implements the Plugin trait.
+- `default_plugin` - Optional (feature: `default_plugin`). Emits a default plugin alias so `auto_*` macros can omit `plugin = ...`.
 
 # Example
 ```rust
@@ -15,4 +16,4 @@ struct MyPlugin;
 
 // Plugin will automatically implement the Plugin trait
 // and include all registered components, events, resources, etc.
-```
+```

tests/e2e/actions/auto_default_plugin.rs

@@ -0,0 +1,31 @@
+use bevy_app::prelude::*;
+use bevy_auto_plugin::prelude::*;
+use bevy_ecs::prelude::*;
+use bevy_reflect::prelude::*;
+use internal_test_proc_macro::xtest;
+use internal_test_util::type_id_of;
+
+#[derive(AutoPlugin)]
+#[auto_plugin(impl_plugin_trait, default_plugin)]
+struct DefaultPlugin;
+
+#[auto_register_type]
+#[derive(Reflect)]
+struct DefaultedType;
+
+fn app() -> App {
+    let mut app = internal_test_util::create_minimal_app();
+    app.add_plugins(DefaultPlugin);
+    app
+}
+
+#[xtest]
+fn test_auto_default_plugin_register_type() {
+    let app = app();
+    let type_registry = app.world().resource::<AppTypeRegistry>().0.clone();
+    let type_registry = type_registry.read();
+    assert!(
+        type_registry.contains(type_id_of::<DefaultedType>()),
+        "did not auto register DefaultedType"
+    );
+}

tests/e2e/actions/mod.rs

@@ -16,6 +16,8 @@ mod auto_bind_plugin_after_build;
 mod auto_configure_system_set;
 mod auto_configure_system_set_schedule_config;
 mod auto_configure_system_set_schedule_config_multiple_groups;
+#[cfg(feature = "default_plugin")]
+mod auto_default_plugin;
 mod auto_init_resource;
 mod auto_init_resource_generic;
 mod auto_init_state;