Fixed #85845: Added a note in E0369 if the missing trait is PartialEq

compiler/rustc_typeck/src/check/op.rs

@@ -959,6 +959,18 @@ fn suggest_impl_missing(err: &mut DiagnosticBuilder<'_>, ty: Ty<'_>, missing_tra
                 "an implementation of `{}` might be missing for `{}`",
                 missing_trait, ty
             ));
+            // This checks if the missing trait is PartialEq to suggest adding a derive
+            if missing_trait == "std::cmp::PartialEq" {
+                err.note(&format!(
+                    "add `#[derive(PartialEq)]` or manually implement `PartialEq` for `{}`",
+                    ty
+                ));
+            } else if missing_trait == "std::cmp::PartialOrd" {
+                err.note(&format!(
+                    "add `#[derive(PartialOrd)]` or manually implement `PartialOrd` for `{}`",
+                    ty
+                ));
+            }
         }
     }
 }

src/test/ui/binop/issue-28837.stderr

@@ -97,6 +97,7 @@ LL |     a == a;
    |     A
    |
    = note: an implementation of `std::cmp::PartialEq` might be missing for `A`
+   = note: add `#[derive(PartialEq)]` or manually implement `PartialEq` for `A`
 
 error[E0369]: binary operation `!=` cannot be applied to type `A`
   --> $DIR/issue-28837.rs:26:7
@@ -107,6 +108,7 @@ LL |     a != a;
    |     A
    |
    = note: an implementation of `std::cmp::PartialEq` might be missing for `A`
+   = note: add `#[derive(PartialEq)]` or manually implement `PartialEq` for `A`
 
 error[E0369]: binary operation `<` cannot be applied to type `A`
   --> $DIR/issue-28837.rs:28:7
@@ -117,6 +119,7 @@ LL |     a < a;
    |     A
    |
    = note: an implementation of `std::cmp::PartialOrd` might be missing for `A`
+   = note: add `#[derive(PartialOrd)]` or manually implement `PartialOrd` for `A`
 
 error[E0369]: binary operation `<=` cannot be applied to type `A`
   --> $DIR/issue-28837.rs:30:7
@@ -127,6 +130,7 @@ LL |     a <= a;
    |     A
    |
    = note: an implementation of `std::cmp::PartialOrd` might be missing for `A`
+   = note: add `#[derive(PartialOrd)]` or manually implement `PartialOrd` for `A`
 
 error[E0369]: binary operation `>` cannot be applied to type `A`
   --> $DIR/issue-28837.rs:32:7
@@ -137,6 +141,7 @@ LL |     a > a;
    |     A
    |
    = note: an implementation of `std::cmp::PartialOrd` might be missing for `A`
+   = note: add `#[derive(PartialOrd)]` or manually implement `PartialOrd` for `A`
 
 error[E0369]: binary operation `>=` cannot be applied to type `A`
   --> $DIR/issue-28837.rs:34:7
@@ -147,6 +152,7 @@ LL |     a >= a;
    |     A
    |
    = note: an implementation of `std::cmp::PartialOrd` might be missing for `A`
+   = note: add `#[derive(PartialOrd)]` or manually implement `PartialOrd` for `A`
 
 error: aborting due to 15 previous errors
 

src/test/ui/derives/derives-span-PartialEq-enum-struct-variant.stderr

@@ -5,6 +5,7 @@ LL |      x: Error
    |      ^^^^^^^^
    |
    = note: an implementation of `std::cmp::PartialEq` might be missing for `Error`
+   = note: add `#[derive(PartialEq)]` or manually implement `PartialEq` for `Error`
    = note: this error originates in the derive macro `PartialEq` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0369]: binary operation `!=` cannot be applied to type `Error`
@@ -14,6 +15,7 @@ LL |      x: Error
    |      ^^^^^^^^
    |
    = note: an implementation of `std::cmp::PartialEq` might be missing for `Error`
+   = note: add `#[derive(PartialEq)]` or manually implement `PartialEq` for `Error`
    = note: this error originates in the derive macro `PartialEq` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to 2 previous errors

src/test/ui/derives/derives-span-PartialEq-enum.stderr

@@ -5,6 +5,7 @@ LL |      Error
    |      ^^^^^
    |
    = note: an implementation of `std::cmp::PartialEq` might be missing for `Error`
+   = note: add `#[derive(PartialEq)]` or manually implement `PartialEq` for `Error`
    = note: this error originates in the derive macro `PartialEq` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0369]: binary operation `!=` cannot be applied to type `Error`
@@ -14,6 +15,7 @@ LL |      Error
    |      ^^^^^
    |
    = note: an implementation of `std::cmp::PartialEq` might be missing for `Error`
+   = note: add `#[derive(PartialEq)]` or manually implement `PartialEq` for `Error`
    = note: this error originates in the derive macro `PartialEq` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to 2 previous errors

src/test/ui/derives/derives-span-PartialEq-struct.stderr

@@ -5,6 +5,7 @@ LL |     x: Error
    |     ^^^^^^^^
    |
    = note: an implementation of `std::cmp::PartialEq` might be missing for `Error`
+   = note: add `#[derive(PartialEq)]` or manually implement `PartialEq` for `Error`
    = note: this error originates in the derive macro `PartialEq` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0369]: binary operation `!=` cannot be applied to type `Error`
@@ -14,6 +15,7 @@ LL |     x: Error
    |     ^^^^^^^^
    |
    = note: an implementation of `std::cmp::PartialEq` might be missing for `Error`
+   = note: add `#[derive(PartialEq)]` or manually implement `PartialEq` for `Error`
    = note: this error originates in the derive macro `PartialEq` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to 2 previous errors

src/test/ui/derives/derives-span-PartialEq-tuple-struct.stderr

@@ -5,6 +5,7 @@ LL |     Error
    |     ^^^^^
    |
    = note: an implementation of `std::cmp::PartialEq` might be missing for `Error`
+   = note: add `#[derive(PartialEq)]` or manually implement `PartialEq` for `Error`
    = note: this error originates in the derive macro `PartialEq` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0369]: binary operation `!=` cannot be applied to type `Error`
@@ -14,6 +15,7 @@ LL |     Error
    |     ^^^^^
    |
    = note: an implementation of `std::cmp::PartialEq` might be missing for `Error`
+   = note: add `#[derive(PartialEq)]` or manually implement `PartialEq` for `Error`
    = note: this error originates in the derive macro `PartialEq` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to 2 previous errors

src/test/ui/derives/deriving-no-inner-impl-error-message.stderr

@@ -5,6 +5,7 @@ LL |     x: NoCloneOrEq
    |     ^^^^^^^^^^^^^^
    |
    = note: an implementation of `std::cmp::PartialEq` might be missing for `NoCloneOrEq`
+   = note: add `#[derive(PartialEq)]` or manually implement `PartialEq` for `NoCloneOrEq`
    = note: this error originates in the derive macro `PartialEq` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0369]: binary operation `!=` cannot be applied to type `NoCloneOrEq`
@@ -14,6 +15,7 @@ LL |     x: NoCloneOrEq
    |     ^^^^^^^^^^^^^^
    |
    = note: an implementation of `std::cmp::PartialEq` might be missing for `NoCloneOrEq`
+   = note: add `#[derive(PartialEq)]` or manually implement `PartialEq` for `NoCloneOrEq`
    = note: this error originates in the derive macro `PartialEq` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0277]: the trait bound `NoCloneOrEq: Clone` is not satisfied

src/test/ui/issues/issue-62375.stderr

@@ -7,6 +7,7 @@ LL |     a == A::Value;
    |     A
    |
    = note: an implementation of `std::cmp::PartialEq` might be missing for `A`
+   = note: add `#[derive(PartialEq)]` or manually implement `PartialEq` for `A`
 
 error: aborting due to previous error