enable multiple_inherent_impl lint

Cargo.toml

@@ -37,6 +37,7 @@ lossy_float_literal = "warn"
 mem_forget = "warn"
 missing_assert_message = "warn"
 mod_module_files = "warn"
+multiple_inherent_impl = "warn"
 mutex_atomic = "warn"
 negative_feature_names = "warn"
 pub_without_shorthand = "warn"

src/database/key_value/users.rs

@@ -952,8 +952,6 @@ impl service::users::Data for KeyValueDatabase {
     }
 }
 
-impl KeyValueDatabase {}
-
 /// Will only return with Some(username) if the password was not empty and the
 /// username could be successfully parsed.
 /// If utils::string_from_bytes(...) returns an error that username will be skipped

src/utils/error.rs

@@ -87,9 +87,7 @@ impl Error {
         error!("BadConfig: {}", message);
         Self::BadConfig(message)
     }
-}
 
-impl Error {
     pub(crate) fn to_response(&self) -> RumaResponse<UiaaResponse> {
         if let Self::Uiaa(uiaainfo) = self {
             return RumaResponse(UiaaResponse::AuthResponse(uiaainfo.clone()));