Rollup merge of rust-lang#142822 - oli-obk:const-partial-eq, r=fee1-dead

Make `PartialEq` a `const_trait`

r? ``@fee1-dead`` or ``@compiler-errors``

something generally useful but also required for rust-lang#142789

Author: jdonszelmann

library/core/src/cmp.rs

@@ -247,6 +247,8 @@ use crate::ops::ControlFlow;
     append_const_msg
 )]
 #[rustc_diagnostic_item = "PartialEq"]
+#[const_trait]
+#[rustc_const_unstable(feature = "const_trait_impl", issue = "67792")]
 pub trait PartialEq<Rhs: PointeeSized = Self>: PointeeSized {
     /// Tests for `self` and `other` values to be equal, and is used by `==`.
     #[must_use]
@@ -1811,7 +1813,8 @@ mod impls {
     macro_rules! partial_eq_impl {
         ($($t:ty)*) => ($(
             #[stable(feature = "rust1", since = "1.0.0")]
-            impl PartialEq for $t {
+            #[rustc_const_unstable(feature = "const_cmp", issue = "92391")]
+            impl const PartialEq for $t {
                 #[inline]
                 fn eq(&self, other: &Self) -> bool { *self == *other }
                 #[inline]
@@ -2018,9 +2021,10 @@ mod impls {
     // & pointers
 
     #[stable(feature = "rust1", since = "1.0.0")]
-    impl<A: PointeeSized, B: PointeeSized> PartialEq<&B> for &A
+    #[rustc_const_unstable(feature = "const_cmp", issue = "92391")]
+    impl<A: PointeeSized, B: PointeeSized> const PartialEq<&B> for &A
     where
-        A: PartialEq<B>,
+        A: ~const PartialEq<B>,
     {
         #[inline]
         fn eq(&self, other: &&B) -> bool {
@@ -2089,9 +2093,10 @@ mod impls {
     // &mut pointers
 
     #[stable(feature = "rust1", since = "1.0.0")]
-    impl<A: PointeeSized, B: PointeeSized> PartialEq<&mut B> for &mut A
+    #[rustc_const_unstable(feature = "const_cmp", issue = "92391")]
+    impl<A: PointeeSized, B: PointeeSized> const PartialEq<&mut B> for &mut A
     where
-        A: PartialEq<B>,
+        A: ~const PartialEq<B>,
     {
         #[inline]
         fn eq(&self, other: &&mut B) -> bool {
@@ -2158,9 +2163,10 @@ mod impls {
     impl<A: PointeeSized> Eq for &mut A where A: Eq {}
 
     #[stable(feature = "rust1", since = "1.0.0")]
-    impl<A: PointeeSized, B: PointeeSized> PartialEq<&mut B> for &A
+    #[rustc_const_unstable(feature = "const_cmp", issue = "92391")]
+    impl<A: PointeeSized, B: PointeeSized> const PartialEq<&mut B> for &A
     where
-        A: PartialEq<B>,
+        A: ~const PartialEq<B>,
     {
         #[inline]
         fn eq(&self, other: &&mut B) -> bool {
@@ -2173,9 +2179,10 @@ mod impls {
     }
 
     #[stable(feature = "rust1", since = "1.0.0")]
-    impl<A: PointeeSized, B: PointeeSized> PartialEq<&B> for &mut A
+    #[rustc_const_unstable(feature = "const_cmp", issue = "92391")]
+    impl<A: PointeeSized, B: PointeeSized> const PartialEq<&B> for &mut A
     where
-        A: PartialEq<B>,
+        A: ~const PartialEq<B>,
     {
         #[inline]
         fn eq(&self, other: &&B) -> bool {

tests/ui/consts/const_cmp_type_id.rs

@@ -6,11 +6,10 @@ use std::any::TypeId;
 fn main() {
     const {
         assert!(TypeId::of::<u8>() == TypeId::of::<u8>());
-        //~^ ERROR cannot call non-const operator in constants
+        //~^ ERROR the trait bound `TypeId: const PartialEq` is not satisfied
         assert!(TypeId::of::<()>() != TypeId::of::<u8>());
-        //~^ ERROR cannot call non-const operator in constants
+        //~^ ERROR the trait bound `TypeId: const PartialEq` is not satisfied
         let _a = TypeId::of::<u8>() < TypeId::of::<u16>();
-        //~^ ERROR cannot call non-const operator in constants
         // can't assert `_a` because it is not deterministic
         // FIXME(const_trait_impl) make it pass
     }

tests/ui/consts/const_cmp_type_id.stderr

@@ -1,33 +1,15 @@
-error[E0015]: cannot call non-const operator in constants
+error[E0277]: the trait bound `TypeId: const PartialEq` is not satisfied
   --> $DIR/const_cmp_type_id.rs:8:17
    |
 LL |         assert!(TypeId::of::<u8>() == TypeId::of::<u8>());
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-note: impl defined here, but it is not `const`
-  --> $SRC_DIR/core/src/any.rs:LL:COL
-   = note: calls in constants are limited to constant functions, tuple structs and tuple variants
 
-error[E0015]: cannot call non-const operator in constants
+error[E0277]: the trait bound `TypeId: const PartialEq` is not satisfied
   --> $DIR/const_cmp_type_id.rs:10:17
    |
 LL |         assert!(TypeId::of::<()>() != TypeId::of::<u8>());
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-note: impl defined here, but it is not `const`
-  --> $SRC_DIR/core/src/any.rs:LL:COL
-   = note: calls in constants are limited to constant functions, tuple structs and tuple variants
-
-error[E0015]: cannot call non-const operator in constants
-  --> $DIR/const_cmp_type_id.rs:12:18
-   |
-LL |         let _a = TypeId::of::<u8>() < TypeId::of::<u16>();
-   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-note: impl defined here, but it is not `const`
-  --> $SRC_DIR/core/src/any.rs:LL:COL
-   = note: calls in constants are limited to constant functions, tuple structs and tuple variants
 
-error: aborting due to 3 previous errors
+error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0015`.
+For more information about this error, try `rustc --explain E0277`.

tests/ui/consts/fn_trait_refs.stderr

@@ -4,12 +4,6 @@ error[E0635]: unknown feature `const_fn_trait_ref_impls`
 LL | #![feature(const_fn_trait_ref_impls)]
    |            ^^^^^^^^^^^^^^^^^^^^^^^^
 
-error[E0635]: unknown feature `const_cmp`
-  --> $DIR/fn_trait_refs.rs:7:12
-   |
-LL | #![feature(const_cmp)]
-   |            ^^^^^^^^^
-
 error: `~const` can only be applied to `#[const_trait]` traits
   --> $DIR/fn_trait_refs.rs:14:8
    |
@@ -155,21 +149,17 @@ note: `FnMut` can't be used with `~const` because it isn't annotated with `#[con
   --> $SRC_DIR/core/src/ops/function.rs:LL:COL
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
-error[E0015]: cannot call non-const operator in constants
+error[E0277]: the trait bound `(i32, i32, i32): const PartialEq` is not satisfied
   --> $DIR/fn_trait_refs.rs:71:17
    |
 LL |         assert!(test_one == (1, 1, 1));
    |                 ^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: calls in constants are limited to constant functions, tuple structs and tuple variants
 
-error[E0015]: cannot call non-const operator in constants
+error[E0277]: the trait bound `(i32, i32): const PartialEq` is not satisfied
   --> $DIR/fn_trait_refs.rs:74:17
    |
 LL |         assert!(test_two == (2, 2));
    |                 ^^^^^^^^^^^^^^^^^^
-   |
-   = note: calls in constants are limited to constant functions, tuple structs and tuple variants
 
 error[E0015]: cannot call non-const closure in constant functions
   --> $DIR/fn_trait_refs.rs:16:5
@@ -195,7 +185,7 @@ LL |     f()
    |
    = note: calls in constant functions are limited to constant functions, tuple structs and tuple variants
 
-error: aborting due to 22 previous errors
+error: aborting due to 21 previous errors
 
-Some errors have detailed explanations: E0015, E0635.
+Some errors have detailed explanations: E0015, E0277, E0635.
 For more information about an error, try `rustc --explain E0015`.

tests/ui/consts/issue-73976-monomorphic.stderr

@@ -1,13 +1,9 @@
-error[E0015]: cannot call non-const operator in constant functions
+error[E0277]: the trait bound `TypeId: ~const PartialEq` is not satisfied
   --> $DIR/issue-73976-monomorphic.rs:21:5
    |
 LL |     GetTypeId::<T>::VALUE == GetTypeId::<usize>::VALUE
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-note: impl defined here, but it is not `const`
-  --> $SRC_DIR/core/src/any.rs:LL:COL
-   = note: calls in constant functions are limited to constant functions, tuple structs and tuple variants
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0015`.
+For more information about this error, try `rustc --explain E0277`.

tests/ui/consts/issue-90870.rs

@@ -3,22 +3,31 @@
 #![allow(dead_code)]
 
 const fn f(a: &u8, b: &u8) -> bool {
+    //~^ HELP: add `#![feature(const_trait_impl)]` to the crate attributes to enable
+    //~| HELP: add `#![feature(const_trait_impl)]` to the crate attributes to enable
+    //~| HELP: add `#![feature(const_trait_impl)]` to the crate attributes to enable
     a == b
-    //~^ ERROR: cannot call non-const operator in constant functions [E0015]
+    //~^ ERROR: cannot call conditionally-const operator in constant functions
+    //~| ERROR: `PartialEq` is not yet stable as a const trait
     //~| HELP: consider dereferencing here
+    //~| HELP: add `#![feature(const_trait_impl)]` to the crate attributes to enable
 }
 
 const fn g(a: &&&&i64, b: &&&&i64) -> bool {
     a == b
-    //~^ ERROR: cannot call non-const operator in constant functions [E0015]
+    //~^ ERROR: cannot call conditionally-const operator in constant functions
+    //~| ERROR: `PartialEq` is not yet stable as a const trait
     //~| HELP: consider dereferencing here
+    //~| HELP: add `#![feature(const_trait_impl)]` to the crate attributes to enable
 }
 
 const fn h(mut a: &[u8], mut b: &[u8]) -> bool {
     while let ([l, at @ ..], [r, bt @ ..]) = (a, b) {
         if l == r {
-        //~^ ERROR: cannot call non-const operator in constant functions [E0015]
+        //~^ ERROR: cannot call conditionally-const operator in constant functions
+        //~| ERROR: `PartialEq` is not yet stable as a const trait
         //~| HELP: consider dereferencing here
+        //~| HELP: add `#![feature(const_trait_impl)]` to the crate attributes to enable
             a = at;
             b = bt;
         } else {

tests/ui/consts/issue-90870.stderr

@@ -1,39 +1,81 @@
-error[E0015]: cannot call non-const operator in constant functions
-  --> $DIR/issue-90870.rs:6:5
+error[E0658]: cannot call conditionally-const operator in constant functions
+  --> $DIR/issue-90870.rs:9:5
    |
 LL |     a == b
    |     ^^^^^^
    |
    = note: calls in constant functions are limited to constant functions, tuple structs and tuple variants
+   = note: see issue #67792 <https://github.com/rust-lang/rust/issues/67792> for more information
+   = help: add `#![feature(const_trait_impl)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 help: consider dereferencing here
    |
 LL |     *a == *b
    |     +     +
 
-error[E0015]: cannot call non-const operator in constant functions
-  --> $DIR/issue-90870.rs:12:5
+error: `PartialEq` is not yet stable as a const trait
+  --> $DIR/issue-90870.rs:9:5
+   |
+LL |     a == b
+   |     ^^^^^^
+   |
+help: add `#![feature(const_trait_impl)]` to the crate attributes to enable
+   |
+LL + #![feature(const_trait_impl)]
+   |
+
+error[E0658]: cannot call conditionally-const operator in constant functions
+  --> $DIR/issue-90870.rs:17:5
    |
 LL |     a == b
    |     ^^^^^^
    |
    = note: calls in constant functions are limited to constant functions, tuple structs and tuple variants
+   = note: see issue #67792 <https://github.com/rust-lang/rust/issues/67792> for more information
+   = help: add `#![feature(const_trait_impl)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 help: consider dereferencing here
    |
 LL |     ****a == ****b
    |     ++++     ++++
 
-error[E0015]: cannot call non-const operator in constant functions
-  --> $DIR/issue-90870.rs:19:12
+error: `PartialEq` is not yet stable as a const trait
+  --> $DIR/issue-90870.rs:17:5
+   |
+LL |     a == b
+   |     ^^^^^^
+   |
+help: add `#![feature(const_trait_impl)]` to the crate attributes to enable
+   |
+LL + #![feature(const_trait_impl)]
+   |
+
+error[E0658]: cannot call conditionally-const operator in constant functions
+  --> $DIR/issue-90870.rs:26:12
    |
 LL |         if l == r {
    |            ^^^^^^
    |
    = note: calls in constant functions are limited to constant functions, tuple structs and tuple variants
+   = note: see issue #67792 <https://github.com/rust-lang/rust/issues/67792> for more information
+   = help: add `#![feature(const_trait_impl)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 help: consider dereferencing here
    |
 LL |         if *l == *r {
    |            +     +
 
-error: aborting due to 3 previous errors
+error: `PartialEq` is not yet stable as a const trait
+  --> $DIR/issue-90870.rs:26:12
+   |
+LL |         if l == r {
+   |            ^^^^^^
+   |
+help: add `#![feature(const_trait_impl)]` to the crate attributes to enable
+   |
+LL + #![feature(const_trait_impl)]
+   |
+
+error: aborting due to 6 previous errors
 
-For more information about this error, try `rustc --explain E0015`.
+For more information about this error, try `rustc --explain E0658`.

tests/ui/traits/const-traits/call-const-trait-method-pass.rs

@@ -1,6 +1,5 @@
-//@ known-bug: #110395
-
 #![feature(const_trait_impl, const_ops)]
+//@ check-pass
 
 struct Int(i32);
 

tests/ui/traits/const-traits/call-const-trait-method-pass.stderr

@@ -1,5 +1,4 @@
-//@ known-bug: #110395
-// FIXME(const_trait_impl) check-pass
+//@ check-pass
 #![feature(const_trait_impl)]
 
 #[const_trait]

tests/ui/traits/const-traits/call-generic-in-impl.rs

@@ -1,8 +1,7 @@
 //! Basic test for calling methods on generic type parameters in `const fn`.
 
-//@ known-bug: #110395
 //@ compile-flags: -Znext-solver
-// FIXME(const_trait_impl) check-pass
+//@ check-pass
 
 #![feature(const_trait_impl)]