extract some grandpa types to Primitives crate

[yjhmelody]

• I improve type params since many types only want to use Header rather than the Block type.
• These types are used by me in both no_std/std. And I need grandpa justification field be pub.

[bkchr]

Two nitpicks, otherwise it looks good.

[bkchr]

Suggested change

	pub struct GrandpaJustification<Block: BlockT> {
	pub struct GrandpaJustification<Header: HeaderT> {

[yjhmelody]

I also want to use it in this way. But its impls must use Block type.

[bkchr]

Suggested change

	pub justification: sp_finality_grandpa::GrandpaJustification<Block::Header>,
	_block: PhantomData<Block>,
	pub justification: sp_finality_grandpa::GrandpaJustification<Header>,

[davxy]

LGTM.

If we want to go even deeper I think that almost everything concerning communication
can be bounded over Header trait instead of Block.

For example starting from the CurrentRounds

https://github.com/yjhmelody/substrate/blob/6e4f14775ab528d5650ad0e6ed8220bb99601331/client/finality-grandpa/src/environment.rs#L173

The various messages

https://github.com/yjhmelody/substrate/blob/6e4f14775ab528d5650ad0e6ed8220bb99601331/client/finality-grandpa/src/communication/gossip.rs#L347

All the way up to the GossipMessage.

https://github.com/yjhmelody/substrate/blob/6e4f14775ab528d5650ad0e6ed8220bb99601331/client/finality-grandpa/src/communication/gossip.rs#L326

So in short I think that Grandpa mostly requires to be generic over the Header (as the external crate it is using).

Should also be said that in practice it also doesn't make much difference.
Indeed in a lot of places (in Substrate) generics are bound to Block where they can just be bound to Header.

[yjhmelody]

So in short I think that Grandpa mostly requires to be generic over the Header (as the external crate it is using).

Should also be said that in practice it also doesn't make much difference. Indeed in a lot of places (in Substrate) generics are bound to Block where they can just be bound to Header.

Yeah, I know. When grandpa types and logic are used for a specific instance chain, Block trait constraint is enough. But current I need to verifiy grandpa in multi-chains(though all Block types maybe are same). So Header trait is better.

[davxy]

So in short I think that Grandpa mostly requires to be generic over the Header (as the external crate it is using).
Should also be said that in practice it also doesn't make much difference. Indeed in a lot of places (in Substrate) generics are bound to Block where they can just be bound to Header.

Yeah, I know. When grandpa types and logic are used for a specific instance chain, Block trait constraint is enough. But current I need to verifiy grandpa in multi-chains(though all Block types maybe are same). So Header trait is better.

Indeed I was silently pushing for bouding everything to Header :-D
But that is a lot of work and maybe a subject for another PR

[bkchr]

bot merge

[paritytech-processbot]

Waiting for commit status.