rust-lang · compiler-errors · Oct 30, 2023
diff --git a/Cargo.lock b/Cargo.lock
@@ -1011,6 +1011,17 @@ dependencies = [
  "syn 2.0.29",
 ]
 
+[[package]]
+name = "derivative"
+version = "2.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fcc3dd5e9e9c0b295d6e1e4d811fb6f157d5ffd784b8d202fc62eac8035a770b"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 1.0.109",
+]
+
 [[package]]
 name = "derive_builder"
 version = "0.12.0"
@@ -4671,6 +4682,7 @@ name = "rustc_type_ir"
 version = "0.0.0"
 dependencies = [
  "bitflags 1.3.2",
+ "derivative",
  "rustc_data_structures",
  "rustc_index",
  "rustc_macros",

diff --git a/compiler/rustc_type_ir/Cargo.toml b/compiler/rustc_type_ir/Cargo.toml
@@ -12,3 +12,4 @@ rustc_serialize = { path = "../rustc_serialize" }
 rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_macros = { path = "../rustc_macros" }
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
+derivative = "2.2.0"
diff --git a/compiler/rustc_type_ir/src/const_kind.rs b/compiler/rustc_type_ir/src/const_kind.rs
@@ -1,7 +1,6 @@
 use rustc_data_structures::stable_hasher::HashStable;
 use rustc_data_structures::stable_hasher::StableHasher;
 use rustc_serialize::{Decodable, Decoder, Encodable};
-use std::cmp::Ordering;
 use std::fmt;
 use std::hash;
 
@@ -13,7 +12,13 @@ use crate::{
 use self::ConstKind::*;
 
 /// Represents a constant in Rust.
-// #[derive(derive_more::From)]
+#[derive(derivative::Derivative)]
+#[derivative(
+    PartialOrd(bound = ""),
+    PartialOrd = "feature_allow_slow_enum",
+    Ord(bound = ""),
+    Ord = "feature_allow_slow_enum"
+)]
 pub enum ConstKind<I: Interner> {
     /// A const generic parameter.
     Param(I::ParamConst),
@@ -166,33 +171,6 @@ where
     }
 }
 
-impl<I: Interner> PartialOrd for ConstKind<I> {
-    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
-        Some(self.cmp(other))
-    }
-}
-
-impl<I: Interner> Ord for ConstKind<I> {
-    fn cmp(&self, other: &Self) -> Ordering {
-        const_kind_discriminant(self)
-            .cmp(&const_kind_discriminant(other))
-            .then_with(|| match (self, other) {
-                (Param(p1), Param(p2)) => p1.cmp(p2),
-                (Infer(i1), Infer(i2)) => i1.cmp(i2),
-                (Bound(d1, b1), Bound(d2, b2)) => d1.cmp(d2).then_with(|| b1.cmp(b2)),
-                (Placeholder(p1), Placeholder(p2)) => p1.cmp(p2),
-                (Unevaluated(u1), Unevaluated(u2)) => u1.cmp(u2),
-                (Value(v1), Value(v2)) => v1.cmp(v2),
-                (Error(e1), Error(e2)) => e1.cmp(e2),
-                (Expr(e1), Expr(e2)) => e1.cmp(e2),
-                _ => {
-                    debug_assert!(false, "This branch must be unreachable, maybe the match is missing an arm? self = {self:?}, other = {other:?}");
-                    Ordering::Equal
-                }
-            })
-    }
-}
-
 impl<I: Interner> PartialEq for ConstKind<I> {
     fn eq(&self, other: &Self) -> bool {
         match (self, other) {

diff --git a/compiler/rustc_type_ir/src/region_kind.rs b/compiler/rustc_type_ir/src/region_kind.rs
@@ -1,7 +1,6 @@
 use rustc_data_structures::stable_hasher::HashStable;
 use rustc_data_structures::stable_hasher::StableHasher;
 use rustc_serialize::{Decodable, Decoder, Encodable};
-use std::cmp::Ordering;
 use std::fmt;
 use std::hash;
 
@@ -118,6 +117,13 @@ use self::RegionKind::*;
 /// [1]: https://smallcultfollowing.com/babysteps/blog/2013/10/29/intermingled-parameter-lists/
 /// [2]: https://smallcultfollowing.com/babysteps/blog/2013/11/04/intermingled-parameter-lists/
 /// [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/traits/hrtb.html
+#[derive(derivative::Derivative)]
+#[derivative(
+    PartialOrd(bound = ""),
+    PartialOrd = "feature_allow_slow_enum",
+    Ord(bound = ""),
+    Ord = "feature_allow_slow_enum"
+)]
 pub enum RegionKind<I: Interner> {
     /// Region bound in a type or fn declaration which will be
     /// substituted 'early' -- that is, at the same time when type
@@ -222,38 +228,6 @@ impl<I: Interner> PartialEq for RegionKind<I> {
 // This is manually implemented because a derive would require `I: Eq`
 impl<I: Interner> Eq for RegionKind<I> {}
 
-// This is manually implemented because a derive would require `I: PartialOrd`
-impl<I: Interner> PartialOrd for RegionKind<I> {
-    #[inline]
-    fn partial_cmp(&self, other: &RegionKind<I>) -> Option<Ordering> {
-        Some(self.cmp(other))
-    }
-}
-
-// This is manually implemented because a derive would require `I: Ord`
-impl<I: Interner> Ord for RegionKind<I> {
-    #[inline]
-    fn cmp(&self, other: &RegionKind<I>) -> Ordering {
-        regionkind_discriminant(self).cmp(&regionkind_discriminant(other)).then_with(|| {
-            match (self, other) {
-                (ReEarlyBound(a_r), ReEarlyBound(b_r)) => a_r.cmp(b_r),
-                (ReLateBound(a_d, a_r), ReLateBound(b_d, b_r)) => {
-                    a_d.cmp(b_d).then_with(|| a_r.cmp(b_r))
-                }
-                (ReFree(a_r), ReFree(b_r)) => a_r.cmp(b_r),
-                (ReStatic, ReStatic) => Ordering::Equal,
-                (ReVar(a_r), ReVar(b_r)) => a_r.cmp(b_r),
-                (RePlaceholder(a_r), RePlaceholder(b_r)) => a_r.cmp(b_r),
-                (ReErased, ReErased) => Ordering::Equal,
-                _ => {
-                    debug_assert!(false, "This branch must be unreachable, maybe the match is missing an arm? self = self = {self:?}, other = {other:?}");
-                    Ordering::Equal
-                }
-            }
-        })
-    }
-}
-
 // This is manually implemented because a derive would require `I: Hash`
 impl<I: Interner> hash::Hash for RegionKind<I> {
     fn hash<H: hash::Hasher>(&self, state: &mut H) -> () {

diff --git a/compiler/rustc_type_ir/src/ty_kind.rs b/compiler/rustc_type_ir/src/ty_kind.rs
@@ -3,7 +3,6 @@
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::unify::{EqUnifyValue, UnifyKey};
 use rustc_serialize::{Decodable, Decoder, Encodable};
-use std::cmp::Ordering;
 use std::mem::discriminant;
 use std::{fmt, hash};
 
@@ -114,6 +113,13 @@ pub enum AliasKind {
 /// Types written by the user start out as `hir::TyKind` and get
 /// converted to this representation using `AstConv::ast_ty_to_ty`.
 #[rustc_diagnostic_item = "IrTyKind"]
+#[derive(derivative::Derivative)]
+#[derivative(
+    PartialOrd(bound = ""),
+    PartialOrd = "feature_allow_slow_enum",
+    Ord(bound = ""),
+    Ord = "feature_allow_slow_enum"
+)]
 pub enum TyKind<I: Interner> {
     /// The primitive boolean type. Written as `bool`.
     Bool,
@@ -410,64 +416,6 @@ impl<I: Interner> PartialEq for TyKind<I> {
 // This is manually implemented because a derive would require `I: Eq`
 impl<I: Interner> Eq for TyKind<I> {}
 
-// This is manually implemented because a derive would require `I: PartialOrd`
-impl<I: Interner> PartialOrd for TyKind<I> {
-    #[inline]
-    fn partial_cmp(&self, other: &TyKind<I>) -> Option<Ordering> {
-        Some(self.cmp(other))
-    }
-}
-
-// This is manually implemented because a derive would require `I: Ord`
-impl<I: Interner> Ord for TyKind<I> {
-    #[inline]
-    fn cmp(&self, other: &TyKind<I>) -> Ordering {
-        tykind_discriminant(self).cmp(&tykind_discriminant(other)).then_with(|| {
-            match (self, other) {
-                (Int(a_i), Int(b_i)) => a_i.cmp(b_i),
-                (Uint(a_u), Uint(b_u)) => a_u.cmp(b_u),
-                (Float(a_f), Float(b_f)) => a_f.cmp(b_f),
-                (Adt(a_d, a_s), Adt(b_d, b_s)) => a_d.cmp(b_d).then_with(|| a_s.cmp(b_s)),
-                (Foreign(a_d), Foreign(b_d)) => a_d.cmp(b_d),
-                (Array(a_t, a_c), Array(b_t, b_c)) => a_t.cmp(b_t).then_with(|| a_c.cmp(b_c)),
-                (Slice(a_t), Slice(b_t)) => a_t.cmp(b_t),
-                (RawPtr(a_t), RawPtr(b_t)) => a_t.cmp(b_t),
-                (Ref(a_r, a_t, a_m), Ref(b_r, b_t, b_m)) => {
-                    a_r.cmp(b_r).then_with(|| a_t.cmp(b_t).then_with(|| a_m.cmp(b_m)))
-                }
-                (FnDef(a_d, a_s), FnDef(b_d, b_s)) => a_d.cmp(b_d).then_with(|| a_s.cmp(b_s)),
-                (FnPtr(a_s), FnPtr(b_s)) => a_s.cmp(b_s),
-                (Dynamic(a_p, a_r, a_repr), Dynamic(b_p, b_r, b_repr)) => {
-                    a_p.cmp(b_p).then_with(|| a_r.cmp(b_r).then_with(|| a_repr.cmp(b_repr)))
-                }
-                (Closure(a_p, a_s), Closure(b_p, b_s)) => a_p.cmp(b_p).then_with(|| a_s.cmp(b_s)),
-                (Coroutine(a_d, a_s, a_m), Coroutine(b_d, b_s, b_m)) => {
-                    a_d.cmp(b_d).then_with(|| a_s.cmp(b_s).then_with(|| a_m.cmp(b_m)))
-                }
-                (
-                    CoroutineWitness(a_d, a_s),
-                    CoroutineWitness(b_d, b_s),
-                ) => match Ord::cmp(a_d, b_d) {
-                    Ordering::Equal => Ord::cmp(a_s, b_s),
-                    cmp => cmp,
-                },
-                (Tuple(a_t), Tuple(b_t)) => a_t.cmp(b_t),
-                (Alias(a_i, a_p), Alias(b_i, b_p)) => a_i.cmp(b_i).then_with(|| a_p.cmp(b_p)),
-                (Param(a_p), Param(b_p)) => a_p.cmp(b_p),
-                (Bound(a_d, a_b), Bound(b_d, b_b)) => a_d.cmp(b_d).then_with(|| a_b.cmp(b_b)),
-                (Placeholder(a_p), Placeholder(b_p)) => a_p.cmp(b_p),
-                (Infer(a_t), Infer(b_t)) => a_t.cmp(b_t),
-                (Error(a_e), Error(b_e)) => a_e.cmp(b_e),
-                (Bool, Bool) | (Char, Char) | (Str, Str) | (Never, Never) => Ordering::Equal,
-                _ => {
-                    debug_assert!(false, "This branch must be unreachable, maybe the match is missing an arm? self = {self:?}, other = {other:?}");
-                    Ordering::Equal
-                }
-            }
-        })
-    }
-}
-
 // This is manually implemented because a derive would require `I: Hash`
 impl<I: Interner> hash::Hash for TyKind<I> {
     fn hash<__H: hash::Hasher>(&self, state: &mut __H) -> () {
@@ -614,6 +562,7 @@ impl<I: Interner> DebugWithInfcx<I> for TyKind<I> {
         }
     }
 }
+
 // This is manually implemented because a derive would require `I: Debug`
 impl<I: Interner> fmt::Debug for TyKind<I> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {

diff --git a/src/tools/tidy/src/deps.rs b/src/tools/tidy/src/deps.rs
@@ -142,6 +142,7 @@ const PERMITTED_RUSTC_DEPENDENCIES: &[&str] = &[
     "darling_core",
     "darling_macro",
     "datafrog",
+    "derivative",
     "derive_more",
     "derive_setters",
     "digest",