frame: GenesisBuild::build allowed in no_std (#14107)

* frame: GenesisBuild::build allowed in no_std

i`GenesisBuild::build` function will be required for no_std in no native
runtime world.

`GenesisBuild::build` macro generated function allows to build the runtime
GenesisConfig assembled from all pallets' GenesisConfigs.

* fixes

* GenesisBuild::build avaiable in no-std

- #[cfg(feature = "std")] is not longer added to GenesisBuild implementation.

* system: hash69 available for no-std

* elections-phragmen: panic message fixed for no_std

* frame::suport: doc updated

* test-runtime: default for GenesisConfig

* frame::test-pallet: serde/std added to std feature deps

* Cargo.toml: deps sorted

* Cargo.lock update

cargo update -p frame-support-test-pallet -p frame-support-test

* frame ui tests: cleanup

---------

Co-authored-by: parity-processbot <>

substrate/frame/support/src/lib.rs

@@ -1522,8 +1522,6 @@ pub mod tests {
 
 /// Prelude to be used alongside pallet macro, for ease of use.
 pub mod pallet_prelude {
-	#[cfg(feature = "std")]
-	pub use crate::traits::GenesisBuild;
 	pub use crate::{
 		dispatch::{
 			DispatchClass, DispatchError, DispatchResult, DispatchResultWithPostInfo, Parameter,
@@ -1540,8 +1538,8 @@ pub mod pallet_prelude {
 			},
 		},
 		traits::{
-			ConstU32, EnsureOrigin, Get, GetDefault, GetStorageVersion, Hooks, IsType,
-			PalletInfoAccess, StorageInfoTrait, StorageVersion, TypedGet,
+			ConstU32, EnsureOrigin, GenesisBuild, Get, GetDefault, GetStorageVersion, Hooks,
+			IsType, PalletInfoAccess, StorageInfoTrait, StorageVersion, TypedGet,
 		},
 		Blake2_128, Blake2_128Concat, Blake2_256, CloneNoBound, DebugNoBound, EqNoBound, Identity,
 		PartialEqNoBound, RuntimeDebug, RuntimeDebugNoBound, Twox128, Twox256, Twox64Concat,

substrate/frame/support/src/traits.rs

@@ -80,11 +80,9 @@ pub use metadata::{
 };
 
 mod hooks;
-#[cfg(feature = "std")]
-pub use hooks::GenesisBuild;
 pub use hooks::{
-	Hooks, IntegrityTest, OnFinalize, OnGenesis, OnIdle, OnInitialize, OnRuntimeUpgrade,
-	OnTimestampSet,
+	GenesisBuild, Hooks, IntegrityTest, OnFinalize, OnGenesis, OnIdle, OnInitialize,
+	OnRuntimeUpgrade, OnTimestampSet,
 };
 
 pub mod schedule;

substrate/frame/support/src/traits/hooks.rs

@@ -361,13 +361,13 @@ pub trait Hooks<BlockNumber> {
 
 /// A trait to define the build function of a genesis config, T and I are placeholder for pallet
 /// trait and pallet instance.
-#[cfg(feature = "std")]
 pub trait GenesisBuild<T, I = ()>: Default + sp_runtime::traits::MaybeSerializeDeserialize {
 	/// The build function is called within an externalities allowing storage APIs.
 	/// Thus one can write to storage using regular pallet storages.
 	fn build(&self);
 
 	/// Build the storage using `build` inside default storage.
+	#[cfg(feature = "std")]
 	fn build_storage(&self) -> Result<sp_runtime::Storage, String> {
 		let mut storage = Default::default();
 		self.assimilate_storage(&mut storage)?;
@@ -375,6 +375,7 @@ pub trait GenesisBuild<T, I = ()>: Default + sp_runtime::traits::MaybeSerializeD
 	}
 
 	/// Assimilate the storage for this module into pre-existing overlays.
+	#[cfg(feature = "std")]
 	fn assimilate_storage(&self, storage: &mut sp_runtime::Storage) -> Result<(), String> {
 		sp_state_machine::BasicExternalities::execute_with_storage(storage, || {
 			self.build();