constify Add

library/core/src/lib.rs

@@ -175,6 +175,7 @@
 #![feature(const_is_char_boundary)]
 #![feature(const_precise_live_drops)]
 #![feature(const_str_split_at)]
+#![feature(const_trait_impl)]
 #![feature(decl_macro)]
 #![feature(deprecated_suggestion)]
 #![feature(doc_cfg)]

library/core/src/ops/arith.rs

@@ -73,6 +73,7 @@
     append_const_msg
 )]
 #[doc(alias = "+")]
+#[cfg_attr(not(bootstrap), const_trait)]
 pub trait Add<Rhs = Self> {
     /// The resulting type after applying the `+` operator.
     #[stable(feature = "rust1", since = "1.0.0")]
@@ -94,6 +95,7 @@ pub trait Add<Rhs = Self> {
 macro_rules! add_impl {
     ($($t:ty)*) => ($(
         #[stable(feature = "rust1", since = "1.0.0")]
+        #[cfg(bootstrap)]
         impl Add for $t {
             type Output = $t;
 
@@ -103,6 +105,17 @@ macro_rules! add_impl {
             fn add(self, other: $t) -> $t { self + other }
         }
 
+        #[stable(feature = "rust1", since = "1.0.0")]
+        #[cfg(not(bootstrap))]
+        impl const Add for $t {
+            type Output = $t;
+
+            #[inline]
+            #[track_caller]
+            #[rustc_inherit_overflow_checks]
+            fn add(self, other: $t) -> $t { self + other }
+        }
+
         forward_ref_binop! { impl Add, add for $t, $t }
     )*)
 }

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

@@ -1,12 +1,3 @@
-error: const `impl` for trait `Add` which is not marked with `#[const_trait]`
-  --> $DIR/call-const-trait-method-pass.rs:7:12
-   |
-LL | impl const std::ops::Add for Int {
-   |            ^^^^^^^^^^^^^
-   |
-   = note: marking a trait with `#[const_trait]` ensures all default method bodies are `const`
-   = note: adding a non-const method body in the future would be a breaking change
-
 error: const `impl` for trait `PartialEq` which is not marked with `#[const_trait]`
   --> $DIR/call-const-trait-method-pass.rs:15:12
    |
@@ -16,14 +7,6 @@ LL | impl const PartialEq for Int {
    = note: marking a trait with `#[const_trait]` ensures all default method bodies are `const`
    = note: adding a non-const method body in the future would be a breaking change
 
-error[E0015]: cannot call non-const operator in constants
-  --> $DIR/call-const-trait-method-pass.rs:39:22
-   |
-LL | const ADD_INT: Int = Int(1i32) + Int(2i32);
-   |                      ^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: calls in constants are limited to constant functions, tuple structs and tuple variants
-
 error[E0015]: cannot call non-const fn `<Int as PartialEq>::eq` in constant functions
   --> $DIR/call-const-trait-method-pass.rs:20:15
    |
@@ -32,6 +15,6 @@ LL |         !self.eq(other)
    |
    = note: calls in constant functions are limited to constant functions, tuple structs and tuple variants
 
-error: aborting due to 4 previous errors
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0015`.

tests/ui/traits/const-traits/const-and-non-const-impl.stderr

@@ -1,21 +1,3 @@
-error: const `impl` for trait `Add` which is not marked with `#[const_trait]`
-  --> $DIR/const-and-non-const-impl.rs:7:12
-   |
-LL | impl const std::ops::Add for i32 {
-   |            ^^^^^^^^^^^^^
-   |
-   = note: marking a trait with `#[const_trait]` ensures all default method bodies are `const`
-   = note: adding a non-const method body in the future would be a breaking change
-
-error: const `impl` for trait `Add` which is not marked with `#[const_trait]`
-  --> $DIR/const-and-non-const-impl.rs:23:12
-   |
-LL | impl const std::ops::Add for Int {
-   |            ^^^^^^^^^^^^^
-   |
-   = note: marking a trait with `#[const_trait]` ensures all default method bodies are `const`
-   = note: adding a non-const method body in the future would be a breaking change
-
 error[E0119]: conflicting implementations of trait `Add` for type `Int`
   --> $DIR/const-and-non-const-impl.rs:23:1
    |
@@ -38,7 +20,7 @@ LL | impl const std::ops::Add for i32 {
    = note: for more information see https://doc.rust-lang.org/reference/items/implementations.html#orphan-rules
    = note: define and implement a trait or new type instead
 
-error: aborting due to 4 previous errors
+error: aborting due to 2 previous errors
 
 Some errors have detailed explanations: E0117, E0119.
 For more information about an error, try `rustc --explain E0117`.

tests/ui/traits/const-traits/generic-bound.rs

@@ -1,4 +1,4 @@
-//@ known-bug: #110395
+//@ check-pass
 
 #![feature(const_trait_impl)]
 
@@ -26,5 +26,6 @@ const fn twice<T: std::ops::Add>(arg: S<T>) -> S<T> {
 }
 
 fn main() {
+    const _: S<i32> = twice(S(PhantomData));
     let _ = twice(S(PhantomData::<i32>));
 }