Add RemovedPrecompilesAt util for filtering removed precompiles (#1551)

* feat(precompile-utils): implement helper methods

* add RemovedPrecompilesAt for filtering a list of removed precompiles

* impl is_empty() for BoundedVec

* appease clippy

* appease clippy x2

---------

Co-authored-by: Rodrigo Quelhas <[email protected]>

precompiles/src/precompile_set.rs

@@ -129,6 +129,7 @@ impl<T> From<DiscriminantResult<T>> for IsPrecompileResult {
 pub enum PrecompileKind {
 	Single(H160),
 	Prefixed(Vec<u8>),
+	Multiple(Vec<H160>),
 }
 
 #[derive(Debug, Clone)]
@@ -833,6 +834,68 @@ impl<A> IsActivePrecompile for RevertPrecompile<A> {
 	}
 }
 
+/// Precompiles that were removed from a precompile set.
+/// Still considered precompiles but are inactive and always revert.
+pub struct RemovedPrecompilesAt<A>(PhantomData<A>);
+impl<A> PrecompileSetFragment for RemovedPrecompilesAt<A>
+where
+	A: Get<Vec<H160>>,
+{
+	#[inline(always)]
+	fn new() -> Self {
+		Self(PhantomData)
+	}
+
+	#[inline(always)]
+	fn execute<R: pallet_evm::Config>(
+		&self,
+		handle: &mut impl PrecompileHandle,
+	) -> Option<PrecompileResult> {
+		if A::get().contains(&handle.code_address()) {
+			Some(Err(revert("Removed precompile")))
+		} else {
+			None
+		}
+	}
+
+	#[inline(always)]
+	fn is_precompile(&self, address: H160, _gas: u64) -> IsPrecompileResult {
+		IsPrecompileResult::Answer {
+			is_precompile: A::get().contains(&address),
+			extra_cost: 0,
+		}
+	}
+
+	#[inline(always)]
+	fn used_addresses(&self) -> Vec<H160> {
+		A::get()
+	}
+
+	fn summarize_checks(&self) -> Vec<PrecompileCheckSummary> {
+		vec![PrecompileCheckSummary {
+			name: None,
+			precompile_kind: PrecompileKind::Multiple(A::get()),
+			recursion_limit: Some(0),
+			accept_delegate_call: true,
+			callable_by_smart_contract: "Reverts in all cases".into(),
+			callable_by_precompile: "Reverts in all cases".into(),
+		}]
+	}
+}
+
+impl<A> IsActivePrecompile for RemovedPrecompilesAt<A>
+where
+	Self: PrecompileSetFragment,
+{
+	#[inline(always)]
+	fn is_active_precompile(&self, _address: H160, _gas: u64) -> IsPrecompileResult {
+		IsPrecompileResult::Answer {
+			is_precompile: false,
+			extra_cost: 0,
+		}
+	}
+}
+
 /// A precompile that was removed from a precompile set.
 /// Still considered a precompile but is inactive and always revert.
 pub struct RemovedPrecompileAt<A>(PhantomData<A>);

precompiles/src/solidity/codec/bytes.rs

@@ -53,7 +53,7 @@ impl Kind for StringKind {
 /// The `bytes/string` type of Solidity.
 /// It is different from `Vec<u8>` which will be serialized with padding for each `u8` element
 /// of the array, while `Bytes` is tightly packed.
-#[derive(Debug, Eq, PartialEq)]
+#[derive(Debug)]
 pub struct BoundedBytesString<K, S> {
 	data: Vec<u8>,
 	_phantom: PhantomData<(K, S)>,
@@ -68,6 +68,20 @@ impl<K: Kind, S: Get<u32>> Clone for BoundedBytesString<K, S> {
 	}
 }
 
+impl<K1, S1, K2, S2> PartialEq<BoundedBytesString<K2, S2>> for BoundedBytesString<K1, S1> {
+	fn eq(&self, other: &BoundedBytesString<K2, S2>) -> bool {
+		self.data.eq(&other.data)
+	}
+}
+
+impl<K, S> Eq for BoundedBytesString<K, S> {}
+
+impl<K, S> Default for BoundedBytesString<K, S> {
+	fn default() -> Self {
+		Vec::default().into()
+	}
+}
+
 impl<K, S: Get<u32>> BoundedBytesString<K, S> {
 	pub fn as_bytes(&self) -> &[u8] {
 		&self.data

precompiles/src/solidity/codec/native.rs

@@ -380,3 +380,22 @@ impl<T, S> From<BoundedVec<T, S>> for Vec<T> {
 		value.inner
 	}
 }
+
+impl<T, S> Default for BoundedVec<T, S> {
+	fn default() -> Self {
+		Self {
+			inner: Default::default(),
+			_phantom: PhantomData,
+		}
+	}
+}
+
+impl<T, S> BoundedVec<T, S> {
+	pub fn len(&self) -> usize {
+		self.inner.len()
+	}
+
+	pub fn is_empty(&self) -> bool {
+		self.inner.is_empty()
+	}
+}