Ignore digits when deriving BitMexPriceEventId's PartialOrd

This is important because deriving `PartialOrd` normally means that it looks at all the struct's fields _in order_. For this type we want to compare the `timestamp`, but do not care about the `digits`! More importantly, someone could unintentionally change this behaviour by reordering the fields. We also have to ignore the `digits` field for other derived traits, because inconsistencies there could cause trouble[1]. [1]: rust-lang/rust-clippy#1621. Co-authored-by: Daniel Karzel <[email protected]>
get10101 · Jul 26, 2022 · e4ff185 · e4ff185
1 parent dabe497
commit e4ff185
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Showing 3 changed files with 11 additions and 3 deletions.
diff --git a/Cargo.lock b/Cargo.lock
diff --git a/model/Cargo.toml b/model/Cargo.toml
@@ -9,6 +9,7 @@ async-trait = "0.1"
 bdk = { version = "0.19.0", default-features = false }
 bdk-ext = { path = "../bdk-ext" }
 conquer-once = "0.3"
+derivative = "2"
 hex = "0.4"
 itertools = "0.10"
 libp2p-core = { version = "0.33", default-features = false, features = ["serde"] }

diff --git a/model/src/olivia.rs b/model/src/olivia.rs
@@ -1,6 +1,7 @@
 use anyhow::Context;
 use bdk::bitcoin::XOnlyPublicKey;
 use conquer_once::Lazy;
+use derivative::Derivative;
 use maia_core::secp256k1_zkp::SecretKey;
 use serde::Deserialize;
 use serde_with::DeserializeFromStr;
@@ -45,12 +46,17 @@ pub struct Attestation {
     pub scalars: Vec<SecretKey>,
 }
 
-#[derive(
-    Debug, Clone, Copy, SerializeDisplay, DeserializeFromStr, PartialEq, Eq, Hash, PartialOrd, Ord,
-)]
+#[derive(Derivative, Debug, Clone, Copy, SerializeDisplay, DeserializeFromStr)]
+#[derivative(PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub struct BitMexPriceEventId {
     /// The timestamp this price event refers to.
     timestamp: OffsetDateTime,
+    #[derivative(
+        PartialEq = "ignore",
+        PartialOrd = "ignore",
+        Ord = "ignore",
+        Hash = "ignore"
+    )]
     digits: usize,
 }