Get rid of unsafe (#2686)

A discord bot library should not be using the tools reserved for low
level OS interaction/data structure libraries.

CONTRIBUTING.md

@@ -63,10 +63,9 @@ your code.
 
 ## Unsafe
 
-Code that defines or uses `unsafe` functions must be reasoned with comments.
-`unsafe` code can pose a potential for undefined behaviour related bugs and other
-kinds of bugs to sprout if misused, weakening security. If you commit code containing
-`unsafe`, you should confirm that its usage is necessary and correct.
+Unsafe code is forbidden, and safe alternatives must be found. This can be mitigated by using
+a third party crate to offload the burden of justifying the unsafe code, or finding a safe
+alternative.
 
 # Comment / Documentation style
 

command_attr/src/util.rs

@@ -31,7 +31,7 @@ impl LitExt for Lit {
     fn to_str(&self) -> String {
         match self {
             Self::Str(s) => s.value(),
-            Self::ByteStr(s) => unsafe { String::from_utf8_unchecked(s.value()) },
+            Self::ByteStr(s) => String::from_utf8_lossy(&s.value()).into_owned(),
             Self::Char(c) => c.value().to_string(),
             Self::Byte(b) => (b.value() as char).to_string(),
             _ => panic!("values must be a (byte)string or a char"),

src/http/routing.rs

@@ -5,7 +5,7 @@ use crate::model::id::*;
 
 /// Used to group requests together for ratelimiting.
 #[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
-pub struct RatelimitingBucket(Option<(std::mem::Discriminant<Route<'static>>, Option<NonZeroU64>)>);
+pub struct RatelimitingBucket(Option<(RouteKind, Option<NonZeroU64>)>);
 
 impl RatelimitingBucket {
     #[must_use]
@@ -40,7 +40,20 @@ macro_rules! routes {
             )+
         }
 
+        #[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
+        enum RouteKind {
+            $($name,)+
+        }
+
         impl<$lt> Route<$lt> {
+            fn kind(&self) -> RouteKind {
+                match self {
+                    $(
+                        Self::$name {..} => RouteKind::$name,
+                    )+
+                }
+            }
+
             #[must_use]
             pub fn path(self) -> Cow<'static, str> {
                 match self {
@@ -59,17 +72,12 @@ macro_rules! routes {
                     )+
                 };
 
-                // To avoid adding a lifetime on RatelimitingBucket and causing lifetime infection,
-                // we transmute the Discriminant<Route<'a>> to Discriminant<Route<'static>>.
-                // SAFETY: std::mem::discriminant erases lifetimes.
-                let discriminant = unsafe { std::mem::transmute(std::mem::discriminant(self)) };
-
                 RatelimitingBucket(ratelimiting_kind.map(|r| {
                     let id = match r {
                         RatelimitingKind::PathAndId(id) => Some(id),
                         RatelimitingKind::Path => None,
                     };
-                    (discriminant, id)
+                    (self.kind(), id)
                 }))
             }
 

src/lib.rs

@@ -50,6 +50,7 @@
 //! [gateway docs]: crate::gateway
 #![doc(html_root_url = "https://docs.rs/serenity/*")]
 #![cfg_attr(docsrs, feature(doc_auto_cfg))]
+#![forbid(unsafe_code)]
 #![warn(
     unused,
     rust_2018_idioms,

src/model/guild/audit_log/mod.rs

@@ -1,7 +1,5 @@
 //! Audit log types for administrative actions within guilds.
 
-use std::mem::transmute;
-
 use nonmax::{NonMaxU32, NonMaxU64};
 use serde::ser::{Serialize, Serializer};
 
@@ -70,22 +68,62 @@ impl Action {
     pub fn from_value(value: u8) -> Action {
         match value {
             1 => Action::GuildUpdate,
-            10..=12 => Action::Channel(unsafe { transmute(value) }),
-            13..=15 => Action::ChannelOverwrite(unsafe { transmute(value) }),
-            20..=28 => Action::Member(unsafe { transmute(value) }),
-            30..=32 => Action::Role(unsafe { transmute(value) }),
-            40..=42 => Action::Invite(unsafe { transmute(value) }),
-            50..=52 => Action::Webhook(unsafe { transmute(value) }),
-            60..=62 => Action::Emoji(unsafe { transmute(value) }),
-            72..=75 => Action::Message(unsafe { transmute(value) }),
-            80..=82 => Action::Integration(unsafe { transmute(value) }),
-            83..=85 => Action::StageInstance(unsafe { transmute(value) }),
-            90..=92 => Action::Sticker(unsafe { transmute(value) }),
-            100..=102 => Action::ScheduledEvent(unsafe { transmute(value) }),
-            110..=112 => Action::Thread(unsafe { transmute(value) }),
-            140..=145 => Action::AutoMod(unsafe { transmute(value) }),
-            150..=151 => Action::CreatorMonetization(unsafe { transmute(value) }),
-            192..=193 => Action::VoiceChannelStatus(unsafe { transmute(value) }),
+            10 => Action::Channel(ChannelAction::Create),
+            11 => Action::Channel(ChannelAction::Update),
+            12 => Action::Channel(ChannelAction::Delete),
+            13 => Action::ChannelOverwrite(ChannelOverwriteAction::Create),
+            14 => Action::ChannelOverwrite(ChannelOverwriteAction::Update),
+            15 => Action::ChannelOverwrite(ChannelOverwriteAction::Delete),
+            20 => Action::Member(MemberAction::Kick),
+            21 => Action::Member(MemberAction::Prune),
+            22 => Action::Member(MemberAction::BanAdd),
+            23 => Action::Member(MemberAction::BanRemove),
+            24 => Action::Member(MemberAction::Update),
+            25 => Action::Member(MemberAction::RoleUpdate),
+            26 => Action::Member(MemberAction::MemberMove),
+            27 => Action::Member(MemberAction::MemberDisconnect),
+            28 => Action::Member(MemberAction::BotAdd),
+            30 => Action::Role(RoleAction::Create),
+            31 => Action::Role(RoleAction::Update),
+            32 => Action::Role(RoleAction::Delete),
+            40 => Action::Invite(InviteAction::Create),
+            41 => Action::Invite(InviteAction::Update),
+            42 => Action::Invite(InviteAction::Delete),
+            50 => Action::Webhook(WebhookAction::Create),
+            51 => Action::Webhook(WebhookAction::Update),
+            52 => Action::Webhook(WebhookAction::Delete),
+            60 => Action::Emoji(EmojiAction::Create),
+            61 => Action::Emoji(EmojiAction::Update),
+            62 => Action::Emoji(EmojiAction::Delete),
+            72 => Action::Message(MessageAction::Delete),
+            73 => Action::Message(MessageAction::BulkDelete),
+            74 => Action::Message(MessageAction::Pin),
+            75 => Action::Message(MessageAction::Unpin),
+            80 => Action::Integration(IntegrationAction::Create),
+            81 => Action::Integration(IntegrationAction::Update),
+            82 => Action::Integration(IntegrationAction::Delete),
+            83 => Action::StageInstance(StageInstanceAction::Create),
+            84 => Action::StageInstance(StageInstanceAction::Update),
+            85 => Action::StageInstance(StageInstanceAction::Delete),
+            90 => Action::Sticker(StickerAction::Create),
+            91 => Action::Sticker(StickerAction::Update),
+            92 => Action::Sticker(StickerAction::Delete),
+            100 => Action::ScheduledEvent(ScheduledEventAction::Create),
+            101 => Action::ScheduledEvent(ScheduledEventAction::Update),
+            102 => Action::ScheduledEvent(ScheduledEventAction::Delete),
+            110 => Action::Thread(ThreadAction::Create),
+            111 => Action::Thread(ThreadAction::Update),
+            112 => Action::Thread(ThreadAction::Delete),
+            140 => Action::AutoMod(AutoModAction::RuleCreate),
+            141 => Action::AutoMod(AutoModAction::RuleUpdate),
+            142 => Action::AutoMod(AutoModAction::RuleDelete),
+            143 => Action::AutoMod(AutoModAction::BlockMessage),
+            144 => Action::AutoMod(AutoModAction::FlagToChannel),
+            145 => Action::AutoMod(AutoModAction::UserCommunicationDisabled),
+            150 => Action::CreatorMonetization(CreatorMonetizationAction::RequestCreated),
+            151 => Action::CreatorMonetization(CreatorMonetizationAction::TermsAccepted),
+            192 => Action::VoiceChannelStatus(VoiceChannelStatusAction::StatusUpdate),
+            193 => Action::VoiceChannelStatus(VoiceChannelStatusAction::StatusDelete),
             _ => Action::Unknown(value),
         }
     }

src/model/id.rs

@@ -90,7 +90,7 @@ macro_rules! id_u64 {
 
             impl From<$name> for NonZeroI64 {
                 fn from(id: $name) -> NonZeroI64 {
-                    unsafe {NonZeroI64::new_unchecked(id.get() as i64)}
+                    NonZeroI64::new(id.get() as i64).unwrap()
                 }
             }