From c364e311be5a0a3269283d2ed90f07515b8a5941 Mon Sep 17 00:00:00 2001
From: Danny McClanahan <1305167+cosmicexplorer@users.noreply.github.com>
Date: Sat, 9 Oct 2021 02:11:46 -0400
Subject: [PATCH 1/2] use thiserror to remove error.rs boilerplate

---
 Cargo.lock                 |  9 +++++----
 rust/protocol/Cargo.toml   |  1 +
 rust/protocol/src/error.rs | 33 +++++----------------------------
 3 files changed, 11 insertions(+), 32 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 56957a842..701a986bf 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -868,6 +868,7 @@ dependencies = [
  "rand 0.7.3",
  "sha2",
  "subtle",
+ "thiserror",
  "uuid",
  "x25519-dalek",
 ]
@@ -1899,18 +1900,18 @@ dependencies = [
 
 [[package]]
 name = "thiserror"
-version = "1.0.29"
+version = "1.0.30"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "602eca064b2d83369e2b2f34b09c70b605402801927c65c11071ac911d299b88"
+checksum = "854babe52e4df1653706b98fcfc05843010039b406875930a70e4d9644e5c417"
 dependencies = [
  "thiserror-impl",
 ]
 
 [[package]]
 name = "thiserror-impl"
-version = "1.0.29"
+version = "1.0.30"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bad553cc2c78e8de258400763a647e80e6d1b31ee237275d756f6836d204494c"
+checksum = "aa32fd3f627f367fe16f893e2597ae3c05020f8bba2666a4e6ea73d377e5714b"
 dependencies = [
  "proc-macro2",
  "quote",
diff --git a/rust/protocol/Cargo.toml b/rust/protocol/Cargo.toml
index 820614a5b..b364931eb 100644
--- a/rust/protocol/Cargo.toml
+++ b/rust/protocol/Cargo.toml
@@ -30,6 +30,7 @@ log = "0.4"
 num_enum = "0.5.1"
 uuid = "0.8"
 displaydoc = "0.2"
+thiserror = "1.0.30"
 
 [features]
 armv8 = ["aes/armv8", "aes-gcm-siv/armv8"]
diff --git a/rust/protocol/src/error.rs b/rust/protocol/src/error.rs
index d71778c56..1affac5de 100644
--- a/rust/protocol/src/error.rs
+++ b/rust/protocol/src/error.rs
@@ -6,13 +6,13 @@
 use crate::curve::KeyType;
 
 use displaydoc::Display;
+use thiserror::Error;
 
-use std::error::Error;
 use std::panic::UnwindSafe;
 
 pub type Result<T> = std::result::Result<T, SignalProtocolError>;
 
-#[derive(Debug, Display)]
+#[derive(Debug, Display, Error)]
 pub enum SignalProtocolError {
     /// invalid argument: {0}
     InvalidArgument(String),
@@ -20,9 +20,9 @@ pub enum SignalProtocolError {
     InvalidState(&'static str, String),
 
     /// failed to decode protobuf: {0}
-    ProtobufDecodingError(prost::DecodeError),
+    ProtobufDecodingError(#[from] prost::DecodeError),
     /// failed to encode protobuf: {0}
-    ProtobufEncodingError(prost::EncodeError),
+    ProtobufEncodingError(#[from] prost::EncodeError),
     /// protobuf encoding was invalid
     InvalidProtobufEncoding,
 
@@ -93,7 +93,7 @@ pub enum SignalProtocolError {
     /// error in method call '{0}': {1}
     ApplicationCallbackError(
         &'static str,
-        Box<dyn std::error::Error + Send + Sync + UnwindSafe + 'static>,
+        #[source] Box<dyn std::error::Error + Send + Sync + UnwindSafe + 'static>,
     ),
 
     /// invalid sealed sender message {0}
@@ -103,26 +103,3 @@ pub enum SignalProtocolError {
     /// self send of a sealed sender message
     SealedSenderSelfSend,
 }
-
-impl Error for SignalProtocolError {
-    fn source(&self) -> Option<&(dyn Error + 'static)> {
-        match self {
-            SignalProtocolError::ProtobufEncodingError(e) => Some(e),
-            SignalProtocolError::ProtobufDecodingError(e) => Some(e),
-            SignalProtocolError::ApplicationCallbackError(_, e) => Some(e.as_ref()),
-            _ => None,
-        }
-    }
-}
-
-impl From<prost::DecodeError> for SignalProtocolError {
-    fn from(value: prost::DecodeError) -> SignalProtocolError {
-        SignalProtocolError::ProtobufDecodingError(value)
-    }
-}
-
-impl From<prost::EncodeError> for SignalProtocolError {
-    fn from(value: prost::EncodeError) -> SignalProtocolError {
-        SignalProtocolError::ProtobufEncodingError(value)
-    }
-}

From de8d7f1ec7aad1414aa134b76a6328a9dc08aa00 Mon Sep 17 00:00:00 2001
From: Danny McClanahan <1305167+cosmicexplorer@users.noreply.github.com>
Date: Sun, 10 Oct 2021 15:06:17 -0400
Subject: [PATCH 2/2] add note on removing duplicated stack trace information

---
 rust/protocol/src/error.rs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/rust/protocol/src/error.rs b/rust/protocol/src/error.rs
index 1affac5de..ae4232603 100644
--- a/rust/protocol/src/error.rs
+++ b/rust/protocol/src/error.rs
@@ -19,6 +19,9 @@ pub enum SignalProtocolError {
     /// invalid state for call to {0} to succeed: {1}
     InvalidState(&'static str, String),
 
+    // TODO: avoid duplicating error information in the Display impl and the #[from] or #[source]
+    // attribute if/when we switch to using an error reporting mechanism supporting stack traces:
+    // see https://github.com/yaahc/blog.rust-lang.org/blob/master/posts/inside-rust/2021-05-15-What-the-error-handling-project-group-is-working-towards.md#duplicate-information-issue
     /// failed to decode protobuf: {0}
     ProtobufDecodingError(#[from] prost::DecodeError),
     /// failed to encode protobuf: {0}