Remove As (#2602)

* Start to remove the `As` bound on `SimpleArtithmetic`

This just introduces standard numeric bounds, assuming a minimum of
`u32`. Also included is a saturating from/into trait allowing ergonomic
infallible conversion when you don't care if it saturates.

* Remove As from Balances trait

* Remove As from Aura module

* Remove As from Babe module

* Expunge `As` from contract

* Council module

* Democracy

* Finality tracker

* Grandpa

* First bit of indices

* indices

* Line lengths

* session

* system

* Staking

* Square up all other uses of As.

* RHD update

* Fix build/test

* Remove As trait

* line widths

* Remove final As ref

* Update srml/staking/src/lib.rs

Co-Authored-By: Bastian Köcher <bkchr@users.noreply.github.com>

* Update core/client/src/cht.rs

Co-Authored-By: Bastian Köcher <bkchr@users.noreply.github.com>

* Update core/client/db/src/light.rs

Co-Authored-By: Bastian Köcher <bkchr@users.noreply.github.com>

* Apply suggestions from code review

Co-Authored-By: Bastian Köcher <bkchr@users.noreply.github.com>

* whitespace

* Apply suggestions from code review

Co-Authored-By: Bastian Köcher <bkchr@users.noreply.github.com>
Co-Authored-By: André Silva <andre.beat@gmail.com>

* Bring back u32 check for number on CLI

substrate/core/client/db/src/cache/list_cache.rs

@@ -44,7 +44,9 @@ use std::collections::BTreeSet;
 use log::warn;
 
 use client::error::{Error as ClientError, Result as ClientResult};
-use runtime_primitives::traits::{Block as BlockT, NumberFor, As, Zero};
+use runtime_primitives::traits::{
+	Block as BlockT, NumberFor, Zero, Bounded, SaturatedConversion, CheckedSub
+};
 
 use crate::cache::{CacheItemT, ComplexBlockId, EntryType};
 use crate::cache::list_entry::{Entry, StorageEntry};
@@ -135,7 +137,7 @@ impl<Block: BlockT, T: CacheItemT, S: Storage<Block, T>> ListCache<Block, T, S>
 
 			// BUT since we're not guaranteeing to provide correct values for forks
 			// behind the finalized block, check if the block is finalized first
-			if !chain::is_finalized_block(&self.storage, at, As::sa(::std::u64::MAX))? {
+			if !chain::is_finalized_block(&self.storage, at, Bounded::max_value())? {
 				return Ok(None);
 			}
 
@@ -349,9 +351,9 @@ impl<Block: BlockT, T: CacheItemT, S: Storage<Block, T>> ListCache<Block, T, S>
 	) {
 		let mut do_pruning = || -> ClientResult<()> {
 			// calculate last ancient block number
-			let ancient_block = match block.number.as_().checked_sub(self.prune_depth.as_()) {
-				Some(number) => match self.storage.read_id(As::sa(number))? {
-					Some(hash) => ComplexBlockId::new(hash, As::sa(number)),
+			let ancient_block = match block.number.checked_sub(&self.prune_depth) {
+				Some(number) => match self.storage.read_id(number)? {
+					Some(hash) => ComplexBlockId::new(hash, number),
 					None => return Ok(()),
 				},
 				None => return Ok(()),

substrate/core/client/db/src/cache/mod.rs

@@ -25,7 +25,7 @@ use client::blockchain::Cache as BlockchainCache;
 use client::error::Result as ClientResult;
 use parity_codec::{Encode, Decode};
 use runtime_primitives::generic::BlockId;
-use runtime_primitives::traits::{Block as BlockT, Header as HeaderT, NumberFor, As, Zero};
+use runtime_primitives::traits::{Block as BlockT, Header as HeaderT, NumberFor, Zero};
 use consensus_common::well_known_cache_keys::Id as CacheKeyId;
 use crate::utils::{self, COLUMN_META, db_err};
 
@@ -36,7 +36,7 @@ mod list_entry;
 mod list_storage;
 
 /// Minimal post-finalization age age of finalized blocks before they'll pruned.
-const PRUNE_DEPTH: u64 = 1024;
+const PRUNE_DEPTH: u32 = 1024;
 
 /// The type of entry that is inserted to the cache.
 #[derive(Clone, Copy, Debug, PartialEq)]
@@ -166,7 +166,7 @@ fn get_cache_helper<'a, Block: BlockT>(
 					cache,
 				},
 			),
-			As::sa(PRUNE_DEPTH),
+			PRUNE_DEPTH.into(),
 			best_finalized_block.clone(),
 		)
 	})