From 8d0df0e99f0dbd7fa2e433199cd10a9abe015121 Mon Sep 17 00:00:00 2001
From: Nuno Alexandre <hi@nunoalexandre.com>
Date: Mon, 20 Apr 2020 14:13:49 +0200
Subject: [PATCH 1/2] core: Add thiserror as a dependency

---
 Cargo.lock      | 1 +
 core/Cargo.toml | 1 +
 2 files changed, 2 insertions(+)

diff --git a/Cargo.lock b/Cargo.lock
index b585c7cb..267aedca 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -3699,6 +3699,7 @@ dependencies = [
  "rand 0.7.3",
  "sp-core",
  "sp-runtime",
+ "thiserror",
 ]
 
 [[package]]
diff --git a/core/Cargo.toml b/core/Cargo.toml
index 9abe3f77..f2ebeb0b 100644
--- a/core/Cargo.toml
+++ b/core/Cargo.toml
@@ -21,6 +21,7 @@ std = [
 [dependencies]
 derive-try-from-primitive = "1.0.0"
 rand = { version = "0.7.2", optional = true }
+thiserror = "1.0"
 
 [dependencies.parity-scale-codec]
 default-features = false

From f0789165d104030d6c5d6eece363fe559fb14092 Mon Sep 17 00:00:00 2001
From: Nuno Alexandre <hi@nunoalexandre.com>
Date: Mon, 20 Apr 2020 14:33:50 +0200
Subject: [PATCH 2/2] core: Make RegistryError derive thiserror

---
 cli/src/lib.rs          |  2 +-
 core/src/error.rs       | 77 +++++++++++++++++------------------------
 runtime/src/registry.rs |  2 +-
 3 files changed, 34 insertions(+), 47 deletions(-)

diff --git a/cli/src/lib.rs b/cli/src/lib.rs
index e0f5225d..5e902b8f 100644
--- a/cli/src/lib.rs
+++ b/cli/src/lib.rs
@@ -151,7 +151,7 @@ pub enum CommandError {
 /// The subset of possible errors having led a transaction to failure.
 #[derive(Debug, ThisError)]
 pub enum TransactionError {
-    #[error("{0}")]
+    #[error(transparent)]
     RegistryError(RegistryError),
 
     #[error("{0:?}")]
diff --git a/core/src/error.rs b/core/src/error.rs
index 301003ae..6d4bd772 100644
--- a/core/src/error.rs
+++ b/core/src/error.rs
@@ -17,66 +17,53 @@ use crate::DispatchError;
 
 use derive_try_from_primitive::TryFromPrimitive;
 use std::convert::{TryFrom, TryInto};
+use thiserror::Error as ThisError;
 
-#[derive(Clone, Copy, Debug, Eq, PartialEq, TryFromPrimitive)]
+#[derive(Clone, Copy, Debug, Eq, PartialEq, ThisError, TryFromPrimitive)]
 #[repr(u8)]
 /// Errors describing failed Registry transactions.
 pub enum RegistryError {
+    #[error("the provided checkpoint does not exist")]
     InexistentCheckpointId = 0,
+
+    #[error("a registered project must have an initial checkpoint")]
+    InexistentInitialProjectCheckpoint,
+
+    #[error("the provided org does not exist")]
     InexistentOrg,
+
+    #[error("the provided project does not exist")]
+    InexistentProjectId,
+
+    #[error("the provided user does not exist")]
     InexistentUser,
+
+    #[error("an org with the same ID already exists")]
     DuplicateOrgId,
+
+    #[error("a project with the same ID already exists")]
     DuplicateProjectId,
+
+    #[error("a user with the same ID already exists.")]
     DuplicateUserId,
-    InexistentProjectId,
+
+    #[error("the provided fee is insufficient")]
     InsufficientFee,
+
+    #[error("the sender is not a project member")]
     InsufficientSenderPermissions,
-    InexistentParentCheckpoint,
-    InexistentInitialProjectCheckpoint,
+
+    #[error("the provided checkpoint is not a descendant of the project's initial checkpoint")]
     InvalidCheckpointAncestry,
-    NonUnregisterableUser,
-    UnregisterableOrg,
-    UserAccountAssociated,
-}
 
-impl From<RegistryError> for &'static str {
-    fn from(error: RegistryError) -> &'static str {
-        match error {
-            RegistryError::InexistentCheckpointId => "The provided checkpoint does not exist",
-            RegistryError::InexistentOrg => "The provided org does not exist",
-            RegistryError::InexistentUser => "The provided user does not exist",
-            RegistryError::DuplicateOrgId => "An org with the same ID already exists.",
-            RegistryError::DuplicateProjectId => "A project with a similar ID already exists.",
-            RegistryError::DuplicateUserId => "A user with the same ID already exists.",
-            RegistryError::InexistentProjectId => "Project does not exist",
-            RegistryError::InsufficientFee => "The provided fee is insufficient.",
-            RegistryError::InsufficientSenderPermissions => "Sender is not a project member",
-            RegistryError::InexistentParentCheckpoint => "Parent checkpoint does not exist",
-            RegistryError::InexistentInitialProjectCheckpoint => {
-                "A registered project must have an initial checkpoint."
-            }
-            RegistryError::InvalidCheckpointAncestry => {
-                "The provided checkpoint is not a descendant of the project's initial checkpoint."
-            }
-            RegistryError::NonUnregisterableUser => {
-                "The provided user is not eligible for unregistration."
-            }
-            RegistryError::UnregisterableOrg => {
-                "The provided org is not elibile for unregistration."
-            }
-            RegistryError::UserAccountAssociated => {
-                "The account is already associated with a user."
-            }
-        }
-    }
-}
+    #[error("the provided user is not eligible for unregistration")]
+    UnregisterableUser,
 
-#[cfg(feature = "std")]
-impl core::fmt::Display for RegistryError {
-    fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
-        let s: &str = self.clone().into();
-        write!(f, "{}", s)
-    }
+    #[error("the provided org is not elibile for unregistration")]
+    UnregisterableOrg,
+
+    #[error("the account is already associated with a user")]
+    UserAccountAssociated,
 }
 
 // The index with which the registry runtime module is declared
diff --git a/runtime/src/registry.rs b/runtime/src/registry.rs
index d3f690bd..dbc343c7 100644
--- a/runtime/src/registry.rs
+++ b/runtime/src/registry.rs
@@ -273,7 +273,7 @@ decl_module! {
                         Ok(())
                     }
                     else {
-                        Err(RegistryError::NonUnregisterableUser.into())
+                        Err(RegistryError::UnregisterableUser.into())
                     }
                 }
             }