From baef1db40fd3cac414b4ee16f2035e026d316ff7 Mon Sep 17 00:00:00 2001
From: Michael Sproul <michael@sigmaprime.io>
Date: Mon, 1 Mar 2021 00:57:13 +0000
Subject: [PATCH] Lint for sum and product in consensus code (#2226)

## Issue Addressed

Closes #1621

## Proposed Changes

Use the `disallowed_method` lint to ban uses of `Iterator::{sum,product}` from `types` and `state_processing`.

## Additional Info

The lint is turned off in the tree hash caching code, as it is performance sensitive and overflowy arithmetic is already allowed there.
---
 consensus/state_processing/clippy.toml              | 5 +++++
 consensus/state_processing/src/lib.rs               | 1 +
 consensus/types/clippy.toml                         | 5 +++++
 consensus/types/src/beacon_state/tree_hash_cache.rs | 1 +
 consensus/types/src/lib.rs                          | 1 +
 5 files changed, 13 insertions(+)
 create mode 100644 consensus/state_processing/clippy.toml
 create mode 100644 consensus/types/clippy.toml

diff --git a/consensus/state_processing/clippy.toml b/consensus/state_processing/clippy.toml
new file mode 100644
index 000000000..e23d2ed05
--- /dev/null
+++ b/consensus/state_processing/clippy.toml
@@ -0,0 +1,5 @@
+# Disallow sum and product methods which are prone to overflow.
+disallowed-methods = [
+    "core::iter::traits::iterator::Iterator::sum",
+    "core::iter::traits::iterator::Iterator::product",
+]
diff --git a/consensus/state_processing/src/lib.rs b/consensus/state_processing/src/lib.rs
index 4a04c0244..3ae90f885 100644
--- a/consensus/state_processing/src/lib.rs
+++ b/consensus/state_processing/src/lib.rs
@@ -1,4 +1,5 @@
 #![deny(clippy::integer_arithmetic)]
+#![deny(clippy::disallowed_method)]
 
 #[macro_use]
 mod macros;
diff --git a/consensus/types/clippy.toml b/consensus/types/clippy.toml
new file mode 100644
index 000000000..e23d2ed05
--- /dev/null
+++ b/consensus/types/clippy.toml
@@ -0,0 +1,5 @@
+# Disallow sum and product methods which are prone to overflow.
+disallowed-methods = [
+    "core::iter::traits::iterator::Iterator::sum",
+    "core::iter::traits::iterator::Iterator::product",
+]
diff --git a/consensus/types/src/beacon_state/tree_hash_cache.rs b/consensus/types/src/beacon_state/tree_hash_cache.rs
index ddd85bb93..ee8cfb2dd 100644
--- a/consensus/types/src/beacon_state/tree_hash_cache.rs
+++ b/consensus/types/src/beacon_state/tree_hash_cache.rs
@@ -1,4 +1,5 @@
 #![allow(clippy::integer_arithmetic)]
+#![allow(clippy::disallowed_method)]
 
 use super::Error;
 use crate::{BeaconState, EthSpec, Hash256, Slot, Unsigned, Validator};
diff --git a/consensus/types/src/lib.rs b/consensus/types/src/lib.rs
index be86daad5..5016b6f13 100644
--- a/consensus/types/src/lib.rs
+++ b/consensus/types/src/lib.rs
@@ -4,6 +4,7 @@
 #![recursion_limit = "128"]
 // Clippy lint set up
 #![deny(clippy::integer_arithmetic)]
+#![deny(clippy::disallowed_method)]
 
 #[macro_use]
 extern crate lazy_static;