Adds ability to provide defaults for types provided by construct_runtime (#14682)

* Adds ability to use defaults for verbatim types

* Adds RuntimeOrigin and PalletInfo in DefaultConfig

* Adds RuntimeEvent in DefaultConfig

* Adds RuntimeEvent in DefaultConfig

* Minor fix

* Minor fix

* Everything in frame_system can now have a default

* Adds docs

* Adds UI Test for no_bounds

* Updates docs

* Adds UI tests for verbatim

* Minor update

* Minor updates

* Minor updates

* Addresses review comments

* Fixes test

* Update frame/support/procedural/src/derive_impl.rs

Co-authored-by: Keith Yeung <kungfukeith11@gmail.com>

* Minor fix

* Minor

* Fixes build

* Uses runtime_type

* Fixes comment

* Fixes comment

* Fixes test

* Uses no_aggregated_types as an option in derive_impl

* Uses specific imports

* Fmt

* Updates doc

* Update frame/support/procedural/src/derive_impl.rs

Co-authored-by: Bastian Köcher <git@kchr.de>

* Update frame/support/procedural/src/derive_impl.rs

Co-authored-by: Bastian Köcher <git@kchr.de>

* Addresses review comment

* Addresses review comment

* fmt

* Renames test files

* Adds docs using docify

* Fixes test

* Fixes UI tests

---------

Co-authored-by: Keith Yeung <kungfukeith11@gmail.com>
Co-authored-by: Bastian Köcher <git@kchr.de>

substrate/frame/support/procedural/src/pallet/parse/config.rs

@@ -34,12 +34,16 @@ mod keyword {
 	syn::custom_keyword!(frame_system);
 	syn::custom_keyword!(disable_frame_system_supertrait_check);
 	syn::custom_keyword!(no_default);
+	syn::custom_keyword!(no_default_bounds);
 	syn::custom_keyword!(constant);
 }
 
 #[derive(Default)]
 pub struct DefaultTrait {
-	pub items: Vec<syn::TraitItem>,
+	/// A bool for each sub-trait item indicates whether the item has
+	/// `#[pallet::no_default_bounds]` attached to it. If true, the item will not have any bounds
+	/// in the generated default sub-trait.
+	pub items: Vec<(syn::TraitItem, bool)>,
 	pub has_system: bool,
 }
 
@@ -142,6 +146,8 @@ impl syn::parse::Parse for DisableFrameSystemSupertraitCheck {
 pub enum PalletAttrType {
 	#[peek(keyword::no_default, name = "no_default")]
 	NoDefault(keyword::no_default),
+	#[peek(keyword::no_default_bounds, name = "no_default_bounds")]
+	NoBounds(keyword::no_default_bounds),
 	#[peek(keyword::constant, name = "constant")]
 	Constant(keyword::constant),
 }
@@ -366,6 +372,7 @@ impl ConfigDef {
 
 			let mut already_no_default = false;
 			let mut already_constant = false;
+			let mut already_no_default_bounds = false;
 
 			while let Ok(Some(pallet_attr)) =
 				helper::take_first_item_pallet_attr::<PalletAttr>(trait_item)
@@ -403,15 +410,31 @@ impl ConfigDef {
 
 						already_no_default = true;
 					},
+					(PalletAttrType::NoBounds(_), _) => {
+						if !enable_default {
+							return Err(syn::Error::new(
+								pallet_attr._bracket.span.join(),
+								"`#[pallet:no_default_bounds]` can only be used if `#[pallet::config(with_default)]` \
+								has been specified"
+							))
+						}
+						if already_no_default_bounds {
+							return Err(syn::Error::new(
+								pallet_attr._bracket.span.join(),
+								"Duplicate #[pallet::no_default_bounds] attribute not allowed.",
+							))
+						}
+						already_no_default_bounds = true;
+					},
 				}
 			}
 
-			if !already_no_default && !is_event && enable_default {
+			if !already_no_default && enable_default {
 				default_sub_trait
 					.as_mut()
 					.expect("is 'Some(_)' if 'enable_default'; qed")
 					.items
-					.push(trait_item.clone());
+					.push((trait_item.clone(), already_no_default_bounds));
 			}
 		}