Allow construct_runtime to take cfg attributes for pallets (#11818)

* Allow construct_runtime to take cfg attributes for pallets

* cargo fmt

* Remove commented out code

* Fixes

* cargo fmt

* Remove inaccurate comments

* Fix typo

* Properly reverse pallets

* Fixes

* cargo fmt

* Add missing newlines

substrate/frame/support/test/tests/construct_runtime_ui/feature_gated_system_pallet.rs

@@ -0,0 +1,14 @@
+use frame_support::construct_runtime;
+
+construct_runtime! {
+	pub enum Runtime where
+		Block = Block,
+		NodeBlock = Block,
+		UncheckedExtrinsic = UncheckedExtrinsic
+	{
+		#[cfg(test)]
+		System: frame_system::{Pallet, Call, Storage, Config, Event<T>},
+	}
+}
+
+fn main() {}

substrate/frame/support/test/tests/construct_runtime_ui/feature_gated_system_pallet.stderr

@@ -0,0 +1,5 @@
+error: `System` pallet declaration is feature gated, please remove any `#[cfg]` attributes
+  --> tests/construct_runtime_ui/feature_gated_system_pallet.rs:10:3
+   |
+10 |         System: frame_system::{Pallet, Call, Storage, Config, Event<T>},
+   |         ^^^^^^

substrate/frame/support/test/tests/construct_runtime_ui/invalid_meta_literal.rs

@@ -0,0 +1,15 @@
+use frame_support::construct_runtime;
+
+construct_runtime! {
+	pub enum Runtime where
+		Block = Block,
+		NodeBlock = Block,
+		UncheckedExtrinsic = UncheckedExtrinsic
+	{
+		System: system::{Pallet},
+		#[cfg(feature = 1)]
+		Balance: balances::{Config, Call},
+	}
+}
+
+fn main() {}

substrate/frame/support/test/tests/construct_runtime_ui/invalid_meta_literal.stderr

@@ -0,0 +1,6 @@
+error: feature = 1
+                 ^ expected one of `<key>`, `all`, `any`, `not` here
+  --> tests/construct_runtime_ui/invalid_meta_literal.rs:10:3
+   |
+10 |         #[cfg(feature = 1)]
+   |         ^

substrate/frame/support/test/tests/construct_runtime_ui/unsupported_meta_structure.rs

@@ -0,0 +1,15 @@
+use frame_support::construct_runtime;
+
+construct_runtime! {
+	pub enum Runtime where
+		Block = Block,
+		NodeBlock = Block,
+		UncheckedExtrinsic = UncheckedExtrinsic
+	{
+		System: system::{Pallet},
+		#[cfg(feature(test))]
+		Balance: balances::{Config, Call},
+	}
+}
+
+fn main() {}

substrate/frame/support/test/tests/construct_runtime_ui/unsupported_meta_structure.stderr

@@ -0,0 +1,6 @@
+error: feature(test)
+              ^ expected one of `=`, `,`, `)` here
+  --> tests/construct_runtime_ui/unsupported_meta_structure.rs:10:3
+   |
+10 |         #[cfg(feature(test))]
+   |         ^

substrate/frame/support/test/tests/construct_runtime_ui/unsupported_pallet_attr.rs

@@ -0,0 +1,15 @@
+use frame_support::construct_runtime;
+
+construct_runtime! {
+	pub enum Runtime where
+		Block = Block,
+		NodeBlock = Block,
+		UncheckedExtrinsic = UncheckedExtrinsic
+	{
+		System: system::{Pallet},
+		#[attr]
+		Balance: balances::{Config, Call},
+	}
+}
+
+fn main() {}

substrate/frame/support/test/tests/construct_runtime_ui/unsupported_pallet_attr.stderr

@@ -0,0 +1,5 @@
+error: Unsupported attribute, only #[cfg] is supported on pallet declarations in `construct_runtime`
+  --> tests/construct_runtime_ui/unsupported_pallet_attr.rs:10:3
+   |
+10 |         #[attr]
+   |         ^

substrate/frame/support/test/tests/pallet.rs

@@ -626,6 +626,8 @@ frame_support::construct_runtime!(
 		System: frame_system exclude_parts { Pallet, Storage },
 		Example: pallet,
 		Example2: pallet2 exclude_parts { Call },
+		#[cfg(feature = "example3")]
+		Example3: pallet3,
 		Example4: pallet4 use_parts { Call },
 	}
 );