Replace custom Void type, change TryFromRaw::Err bound

ruma-events-macros/tests/ruma_events_macros.rs

@@ -1,4 +1,7 @@
-use std::fmt::{Debug, Display, Formatter, Result as FmtResult};
+use std::{
+    convert::Infallible,
+    fmt::{Debug, Display, Formatter, Result as FmtResult},
+};
 
 use serde::{
     de::{DeserializeOwned, Error as SerdeError, Visitor},
@@ -115,14 +118,14 @@ pub trait FromRaw: Sized {
 pub trait TryFromRaw: Sized {
     /// The raw form of this event that deserialization falls back to if deserializing `Self` fails.
     type Raw: DeserializeOwned;
-    type Err: Into<String>;
+    type Err: Display;
 
     fn try_from_raw(_: Self::Raw) -> Result<Self, (Self::Err, Self::Raw)>;
 }
 
 impl<T: FromRaw> TryFromRaw for T {
     type Raw = <T as FromRaw>::Raw;
-    type Err = Void;
+    type Err = Infallible;
 
     fn try_from_raw(raw: Self::Raw) -> Result<Self, (Self::Err, Self::Raw)> {
         Ok(Self::from_raw(raw))
@@ -153,9 +156,9 @@ where
 
         match T::try_from_raw(raw_data) {
             Ok(value) => Ok(EventResult::Ok(value)),
-            Err((msg, raw_data)) => Ok(EventResult::Err(InvalidEvent(
+            Err((err, raw_data)) => Ok(EventResult::Err(InvalidEvent(
                 InnerInvalidEvent::Validation {
-                    message: msg.into(),
+                    message: err.to_string(),
                     raw_data,
                 },
             ))),
@@ -163,14 +166,6 @@ where
     }
 }
 
-pub enum Void {}
-
-impl From<Void> for String {
-    fn from(v: Void) -> Self {
-        match v {}
-    }
-}
-
 /// A basic event.
 pub trait Event: Debug + Serialize + TryFromRaw {
     /// The type of this event's `content` field.
@@ -242,7 +237,7 @@ enum InnerInvalidEvent<T> {
         /// The event data that failed validation.
         raw_data: T,
 
-        /// An message describing why the event was invalid.
+        /// A message describing why the event was invalid.
         message: String,
     },
 }

src/lib.rs

@@ -115,6 +115,7 @@
 //#![deny(warnings)]
 
 use std::{
+    convert::Infallible,
     error::Error,
     fmt::{Debug, Display, Error as FmtError, Formatter, Result as FmtResult},
 };
@@ -226,7 +227,7 @@ enum InnerInvalidEvent<T> {
         /// The event data that failed validation.
         raw_data: T,
 
-        /// An message describing why the event was invalid.
+        /// A message describing why the event was invalid.
         message: String,
     },
 }
@@ -259,31 +260,20 @@ pub trait FromRaw: Sized {
 pub trait TryFromRaw: Sized {
     /// The raw form of this event that deserialization falls back to if deserializing `Self` fails.
     type Raw: DeserializeOwned;
-    type Err: Into<String>;
+    type Err: Display;
 
     fn try_from_raw(_: Self::Raw) -> Result<Self, (Self::Err, Self::Raw)>;
 }
 
 impl<T: FromRaw> TryFromRaw for T {
     type Raw = <T as FromRaw>::Raw;
-    type Err = Void;
+    type Err = Infallible;
 
     fn try_from_raw(raw: Self::Raw) -> Result<Self, (Self::Err, Self::Raw)> {
         Ok(Self::from_raw(raw))
     }
 }
 
-// TODO: Replace with ! once that is stable
-/// An empty type
-#[derive(Debug)]
-pub enum Void {}
-
-impl From<Void> for String {
-    fn from(v: Void) -> Self {
-        match v {}
-    }
-}
-
 /// The result of deserializing an event, which may or may not be valid.
 ///
 /// When data is successfully deserialized and validated, this structure will contain the
@@ -335,9 +325,9 @@ where
 
         match T::try_from_raw(raw_data) {
             Ok(value) => Ok(EventResult::Ok(value)),
-            Err((msg, raw_data)) => Ok(EventResult::Err(InvalidEvent(
+            Err((err, raw_data)) => Ok(EventResult::Err(InvalidEvent(
                 InnerInvalidEvent::Validation {
-                    message: msg.into(),
+                    message: err.to_string(),
                     raw_data,
                 },
             ))),

src/util.rs

@@ -7,7 +7,7 @@ pub fn try_convert_variant<Enum: TryFromRaw, Content: TryFromRaw>(
 ) -> Result<Enum, (String, Enum::Raw)> {
     Content::try_from_raw(raw)
         .map(variant)
-        .map_err(|(msg, raw)| (msg.into(), raw_variant(raw)))
+        .map_err(|(err, raw)| (err.to_string(), raw_variant(raw)))
 }
 
 pub fn serde_json_error_to_generic_de_error<E: serde::de::Error>(error: serde_json::Error) -> E {