Rollup merge of #64110 - estebank:receiver-type, r=Centril

Refer to "`self` type" instead of "receiver type"

Fix https://github.com/rust-lang/rust/issues/42603.

42 files changed, 283 insertions, 150 deletions

diff --git a/src/librustc/error_codes.rs b/src/librustc/error_codes.rs
index 2d09013f675..937a9ea6c1b 100644
--- a/src/librustc/error_codes.rs
+++ b/src/librustc/error_codes.rs
@@ -39,7 +39,7 @@ Generally, `Self: Sized` is used to indicate that the trait should not be used
 as a trait object. If the trait comes from your own crate, consider removing
 this restriction.
 
-### Method references the `Self` type in its arguments or return type
+### Method references the `Self` type in its parameters or return type
 
 This happens when a trait has a method like the following:
 
diff --git a/src/librustc/infer/error_reporting/mod.rs b/src/librustc/infer/error_reporting/mod.rs
index e684ccfeeb7..bf9cb79fb8a 100644
--- a/src/librustc/infer/error_reporting/mod.rs
+++ b/src/librustc/infer/error_reporting/mod.rs
@@ -1627,7 +1627,7 @@ impl<'tcx> ObligationCause<'tcx> {
             MainFunctionType => Error0580("main function has wrong type"),
             StartFunctionType => Error0308("start function has wrong type"),
             IntrinsicType => Error0308("intrinsic has wrong type"),
-            MethodReceiver => Error0308("mismatched method receiver"),
+            MethodReceiver => Error0308("mismatched `self` parameter type"),
 
             // In the case where we have no more specific thing to
             // say, also take a look at the error code, maybe we can
diff --git a/src/librustc/traits/error_reporting.rs b/src/librustc/traits/error_reporting.rs
index b38e1f5f839..03cc00d87e3 100644
--- a/src/librustc/traits/error_reporting.rs
+++ b/src/librustc/traits/error_reporting.rs
@@ -1384,7 +1384,10 @@ impl<'tcx> TyCtxt<'tcx> {
         let mut reported_violations = FxHashSet::default();
         for violation in violations {
             if reported_violations.insert(violation.clone()) {
-                err.note(&violation.error_msg());
+                match violation.span() {
+                    Some(span) => err.span_label(span, violation.error_msg()),
+                    None => err.note(&violation.error_msg()),
+                };
             }
         }
         Some(err)
diff --git a/src/librustc/traits/object_safety.rs b/src/librustc/traits/object_safety.rs
index 7ea7bf0257c..f7f459cd27f 100644
--- a/src/librustc/traits/object_safety.rs
+++ b/src/librustc/traits/object_safety.rs
@@ -20,7 +20,7 @@ use std::borrow::Cow;
 use std::iter::{self};
 use syntax::ast::{self};
 use syntax::symbol::InternedString;
-use syntax_pos::Span;
+use syntax_pos::{Span, DUMMY_SP};
 
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
 pub enum ObjectSafetyViolation {
@@ -32,10 +32,10 @@ pub enum ObjectSafetyViolation {
     SupertraitSelf,
 
     /// Method has something illegal.
-    Method(ast::Name, MethodViolationCode),
+    Method(ast::Name, MethodViolationCode, Span),
 
     /// Associated const.
-    AssocConst(ast::Name),
+    AssocConst(ast::Name, Span),
 }
 
 impl ObjectSafetyViolation {
@@ -46,22 +46,35 @@ impl ObjectSafetyViolation {
             ObjectSafetyViolation::SupertraitSelf =>
                 "the trait cannot use `Self` as a type parameter \
                  in the supertraits or where-clauses".into(),
-            ObjectSafetyViolation::Method(name, MethodViolationCode::StaticMethod) =>
-                format!("method `{}` has no receiver", name).into(),
-            ObjectSafetyViolation::Method(name, MethodViolationCode::ReferencesSelf) =>
-                format!("method `{}` references the `Self` type \
-                         in its arguments or return type", name).into(),
-            ObjectSafetyViolation::Method(name,
-                                            MethodViolationCode::WhereClauseReferencesSelf(_)) =>
-                format!("method `{}` references the `Self` type in where clauses", name).into(),
-            ObjectSafetyViolation::Method(name, MethodViolationCode::Generic) =>
+            ObjectSafetyViolation::Method(name, MethodViolationCode::StaticMethod, _) =>
+                format!("associated function `{}` has no `self` parameter", name).into(),
+            ObjectSafetyViolation::Method(name, MethodViolationCode::ReferencesSelf, _) => format!(
+                "method `{}` references the `Self` type in its parameters or return type",
+                name,
+            ).into(),
+            ObjectSafetyViolation::Method(
+                name,
+                MethodViolationCode::WhereClauseReferencesSelf,
+                _,
+            ) => format!("method `{}` references the `Self` type in where clauses", name).into(),
+            ObjectSafetyViolation::Method(name, MethodViolationCode::Generic, _) =>
                 format!("method `{}` has generic type parameters", name).into(),
-            ObjectSafetyViolation::Method(name, MethodViolationCode::UndispatchableReceiver) =>
-                format!("method `{}`'s receiver cannot be dispatched on", name).into(),
-            ObjectSafetyViolation::AssocConst(name) =>
+            ObjectSafetyViolation::Method(name, MethodViolationCode::UndispatchableReceiver, _) =>
+                format!("method `{}`'s `self` parameter cannot be dispatched on", name).into(),
+            ObjectSafetyViolation::AssocConst(name, _) =>
                 format!("the trait cannot contain associated consts like `{}`", name).into(),
         }
     }
+
+    pub fn span(&self) -> Option<Span> {
+        // When `span` comes from a separate crate, it'll be `DUMMY_SP`. Treat it as `None` so
+        // diagnostics use a `note` instead of a `span_label`.
+        match *self {
+            ObjectSafetyViolation::AssocConst(_, span) |
+            ObjectSafetyViolation::Method(_, _, span) if span != DUMMY_SP => Some(span),
+            _ => None,
+        }
+    }
 }
 
 /// Reasons a method might not be object-safe.
@@ -74,7 +87,7 @@ pub enum MethodViolationCode {
     ReferencesSelf,
 
     /// e.g., `fn foo(&self) where Self: Clone`
-    WhereClauseReferencesSelf(Span),
+    WhereClauseReferencesSelf,
 
     /// e.g., `fn foo<A>()`
     Generic,
@@ -88,9 +101,10 @@ impl<'tcx> TyCtxt<'tcx> {
     /// astconv -- currently, `Self` in supertraits. This is needed
     /// because `object_safety_violations` can't be used during
     /// type collection.
-    pub fn astconv_object_safety_violations(self, trait_def_id: DefId)
-                                            -> Vec<ObjectSafetyViolation>
-    {
+    pub fn astconv_object_safety_violations(
+        self,
+        trait_def_id: DefId,
+    ) -> Vec<ObjectSafetyViolation> {
         debug_assert!(self.generics_of(trait_def_id).has_self);
         let violations = traits::supertrait_def_ids(self, trait_def_id)
             .filter(|&def_id| self.predicates_reference_self(def_id, true))
@@ -128,7 +142,7 @@ impl<'tcx> TyCtxt<'tcx> {
         }
 
         match self.virtual_call_violation_for_method(trait_def_id, method) {
-            None | Some(MethodViolationCode::WhereClauseReferencesSelf(_)) => true,
+            None | Some(MethodViolationCode::WhereClauseReferencesSelf) => true,
             Some(_) => false,
         }
     }
@@ -138,12 +152,15 @@ impl<'tcx> TyCtxt<'tcx> {
         let mut violations: Vec<_> = self.associated_items(trait_def_id)
             .filter(|item| item.kind == ty::AssocKind::Method)
             .filter_map(|item|
-                self.object_safety_violation_for_method(trait_def_id, &item)
-                    .map(|code| ObjectSafetyViolation::Method(item.ident.name, code))
+                self.object_safety_violation_for_method(trait_def_id, &item).map(|code| {
+                    ObjectSafetyViolation::Method(item.ident.name, code, item.ident.span)
+                })
             ).filter(|violation| {
-                if let ObjectSafetyViolation::Method(_,
-                    MethodViolationCode::WhereClauseReferencesSelf(span)) = violation
-                {
+                if let ObjectSafetyViolation::Method(
+                    _,
+                    MethodViolationCode::WhereClauseReferencesSelf,
+                    span,
+                ) = violation {
                     // Using `CRATE_NODE_ID` is wrong, but it's hard to get a more precise id.
                     // It's also hard to get a use site span, so we use the method definition span.
                     self.lint_node_note(
@@ -169,7 +186,7 @@ impl<'tcx> TyCtxt<'tcx> {
 
         violations.extend(self.associated_items(trait_def_id)
             .filter(|item| item.kind == ty::AssocKind::Const)
-            .map(|item| ObjectSafetyViolation::AssocConst(item.ident.name)));
+            .map(|item| ObjectSafetyViolation::AssocConst(item.ident.name, item.ident.span)));
 
         debug!("object_safety_violations_for_trait(trait_def_id={:?}) = {:?}",
                trait_def_id,
@@ -325,8 +342,7 @@ impl<'tcx> TyCtxt<'tcx> {
                 .visit_tys_shallow(|t| {
                     self.contains_illegal_self_type_reference(trait_def_id, t)
                 }) {
-            let span = self.def_span(method.def_id);
-            return Some(MethodViolationCode::WhereClauseReferencesSelf(span));
+            return Some(MethodViolationCode::WhereClauseReferencesSelf);
         }
 
         let receiver_ty = self.liberate_late_bound_regions(
diff --git a/src/librustc_typeck/check/wfcheck.rs b/src/librustc_typeck/check/wfcheck.rs
index f95b3e44bf0..ac8ee43dd08 100644
--- a/src/librustc_typeck/check/wfcheck.rs
+++ b/src/librustc_typeck/check/wfcheck.rs
@@ -762,19 +762,19 @@ fn check_opaque_types<'fcx, 'tcx>(
     substituted_predicates
 }
 
+const HELP_FOR_SELF_TYPE: &str =
+    "consider changing to `self`, `&self`, `&mut self`, `self: Box<Self>`, \
+     `self: Rc<Self>`, `self: Arc<Self>`, or `self: Pin<P>` (where P is one \
+     of the previous types except `Self`)";
+
 fn check_method_receiver<'fcx, 'tcx>(
     fcx: &FnCtxt<'fcx, 'tcx>,
     method_sig: &hir::MethodSig,
     method: &ty::AssocItem,
     self_ty: Ty<'tcx>,
 ) {
-    const HELP_FOR_SELF_TYPE: &str =
-        "consider changing to `self`, `&self`, `&mut self`, `self: Box<Self>`, \
-         `self: Rc<Self>`, `self: Arc<Self>`, or `self: Pin<P>` (where P is one \
-         of the previous types except `Self`)";
     // Check that the method has a valid receiver type, given the type `Self`.
-    debug!("check_method_receiver({:?}, self_ty={:?})",
-           method, self_ty);
+    debug!("check_method_receiver({:?}, self_ty={:?})", method, self_ty);
 
     if !method.method_has_self_argument {
         return;
@@ -805,12 +805,7 @@ fn check_method_receiver<'fcx, 'tcx>(
     if fcx.tcx.features().arbitrary_self_types {
         if !receiver_is_valid(fcx, span, receiver_ty, self_ty, true) {
             // Report error; `arbitrary_self_types` was enabled.
-            fcx.tcx.sess.diagnostic().mut_span_err(
-                span, &format!("invalid method receiver type: {:?}", receiver_ty)
-            ).note("type of `self` must be `Self` or a type that dereferences to it")
-            .help(HELP_FOR_SELF_TYPE)
-            .code(DiagnosticId::Error("E0307".into()))
-            .emit();
+            e0307(fcx, span, receiver_ty);
         }
     } else {
         if !receiver_is_valid(fcx, span, receiver_ty, self_ty, false) {
@@ -830,17 +825,22 @@ fn check_method_receiver<'fcx, 'tcx>(
                 .emit();
             } else {
                 // Report error; would not have worked with `arbitrary_self_types`.
-                fcx.tcx.sess.diagnostic().mut_span_err(
-                    span, &format!("invalid method receiver type: {:?}", receiver_ty)
-                ).note("type must be `Self` or a type that dereferences to it")
-                .help(HELP_FOR_SELF_TYPE)
-                .code(DiagnosticId::Error("E0307".into()))
-                .emit();
+                e0307(fcx, span, receiver_ty);
             }
         }
     }
 }
 
+fn e0307(fcx: &FnCtxt<'fcx, 'tcx>, span: Span, receiver_ty: Ty<'_>) {
+    fcx.tcx.sess.diagnostic().mut_span_err(
+        span,
+        &format!("invalid `self` parameter type: {:?}", receiver_ty)
+    ).note("type of `self` must be `Self` or a type that dereferences to it")
+    .help(HELP_FOR_SELF_TYPE)
+    .code(DiagnosticId::Error("E0307".into()))
+    .emit();
+}
+
 /// Returns whether `receiver_ty` would be considered a valid receiver type for `self_ty`. If
 /// `arbitrary_self_types` is enabled, `receiver_ty` must transitively deref to `self_ty`, possibly
 /// through a `*const/mut T` raw pointer. If the feature is not enabled, the requirements are more
diff --git a/src/librustc_typeck/error_codes.rs b/src/librustc_typeck/error_codes.rs
index b52183d4b1b..093446d2853 100644
--- a/src/librustc_typeck/error_codes.rs
+++ b/src/librustc_typeck/error_codes.rs
@@ -212,7 +212,7 @@ match string {
 E0033: r##"
 This error indicates that a pointer to a trait type cannot be implicitly
 dereferenced by a pattern. Every trait defines a type, but because the
-size of trait implementors isn't fixed, this type has no compile-time size.
+size of trait implementers isn't fixed, this type has no compile-time size.
 Therefore, all accesses to trait types must be through pointers. If you
 encounter this error you should try to avoid dereferencing the pointer.
 
@@ -2425,6 +2425,87 @@ struct Bar<S, T> { x: Foo<S, T> }
 ```
 "##,
 
+E0307: r##"
+This error indicates that the `self` parameter in a method has an invalid
+"reciever type".
+
+Methods take a special first parameter, of which there are three variants:
+`self`, `&self`, and `&mut self`. These are syntactic sugar for
+`self: Self`, `self: &Self`, and `self: &mut Self` respectively.
+
+```
+# struct Foo;
+trait Trait {
+    fn foo(&self);
+//         ^^^^^ `self` here is a reference to the receiver object
+}
+
+impl Trait for Foo {
+    fn foo(&self) {}
+//         ^^^^^ the receiver type is `&Foo`
+}
+```
+
+The type `Self` acts as an alias to the type of the current trait
+implementer, or "receiver type". Besides the already mentioned `Self`,
+`&Self` and `&mut Self` valid receiver types, the following are also valid:
+`self: Box<Self>`, `self: Rc<Self>`, `self: Arc<Self>`, and `self: Pin<P>`
+(where P is one of the previous types except `Self`). Note that `Self` can
+also be the underlying implementing type, like `Foo` in the following
+example:
+
+```
+# struct Foo;
+# trait Trait {
+#     fn foo(&self);
+# }
+impl Trait for Foo {
+    fn foo(self: &Foo) {}
+}
+```
+
+E0307 will be emitted by the compiler when using an invalid reciver type,
+like in the following example:
+
+```compile_fail,E0307
+# struct Foo;
+# struct Bar;
+# trait Trait {
+#     fn foo(&self);
+# }
+impl Trait for Foo {
+    fn foo(self: &Bar) {}
+}
+```
+
+The nightly feature [Arbintrary self types][AST] extends the accepted
+set of receiver types to also include any type that can dereference to
+`Self`:
+
+```
+#![feature(arbitrary_self_types)]
+
+struct Foo;
+struct Bar;
+
+// Because you can dereference `Bar` into `Foo`...
+impl std::ops::Deref for Bar {
+    type Target = Foo;
+
+    fn deref(&self) -> &Foo {
+        &Foo
+    }
+}
+
+impl Foo {
+    fn foo(self: Bar) {}
+//         ^^^^^^^^^ ...it can be used as the receiver type
+}
+```
+
+[AST]: https://doc.rust-lang.org/unstable-book/language-features/arbitrary-self-types.html
+"##,
+
 E0321: r##"
 A cross-crate opt-out trait was implemented on something which wasn't a struct
 or enum type. Erroneous code example:
@@ -4851,7 +4932,6 @@ register_diagnostics! {
 //  E0247,
 //  E0248, // value used as a type, now reported earlier during resolution as E0412
 //  E0249,
-    E0307, // invalid method `self` type
 //  E0319, // trait impls for defaulted traits allowed just for structs/enums
 //  E0372, // coherence not object safe
     E0377, // the trait `CoerceUnsized` may only be implemented for a coercion
diff --git a/src/test/ui/associated-const/associated-const-in-trait.stderr b/src/test/ui/associated-const/associated-const-in-trait.stderr
index dff268a55c9..a5d7fc5b702 100644
--- a/src/test/ui/associated-const/associated-const-in-trait.stderr
+++ b/src/test/ui/associated-const/associated-const-in-trait.stderr
@@ -1,10 +1,11 @@
 error[E0038]: the trait `Trait` cannot be made into an object
   --> $DIR/associated-const-in-trait.rs:9:6
    |
+LL |     const N: usize;
+   |           - the trait cannot contain associated consts like `N`
+...
 LL | impl dyn Trait {
    |      ^^^^^^^^^ the trait `Trait` cannot be made into an object
-   |
-   = note: the trait cannot contain associated consts like `N`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/coherence/coherence-impl-trait-for-trait-object-safe.old.stderr b/src/test/ui/coherence/coherence-impl-trait-for-trait-object-safe.old.stderr
index c38d7456a99..18a7cea95bd 100644
--- a/src/test/ui/coherence/coherence-impl-trait-for-trait-object-safe.old.stderr
+++ b/src/test/ui/coherence/coherence-impl-trait-for-trait-object-safe.old.stderr
@@ -1,10 +1,10 @@
 error[E0038]: the trait `NotObjectSafe` cannot be made into an object
   --> $DIR/coherence-impl-trait-for-trait-object-safe.rs:11:6
    |
+LL | trait NotObjectSafe { fn eq(&self, other: Self); }
+   |                          -- method `eq` references the `Self` type in its parameters or return type
 LL | impl NotObjectSafe for dyn NotObjectSafe { }
    |      ^^^^^^^^^^^^^ the trait `NotObjectSafe` cannot be made into an object
-   |
-   = note: method `eq` references the `Self` type in its arguments or return type
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/coherence/coherence-impl-trait-for-trait-object-safe.re.stderr b/src/test/ui/coherence/coherence-impl-trait-for-trait-object-safe.re.stderr
index c38d7456a99..18a7cea95bd 100644
--- a/src/test/ui/coherence/coherence-impl-trait-for-trait-object-safe.re.stderr
+++ b/src/test/ui/coherence/coherence-impl-trait-for-trait-object-safe.re.stderr
@@ -1,10 +1,10 @@
 error[E0038]: the trait `NotObjectSafe` cannot be made into an object
   --> $DIR/coherence-impl-trait-for-trait-object-safe.rs:11:6
    |
+LL | trait NotObjectSafe { fn eq(&self, other: Self); }
+   |                          -- method `eq` references the `Self` type in its parameters or return type
 LL | impl NotObjectSafe for dyn NotObjectSafe { }
    |      ^^^^^^^^^^^^^ the trait `NotObjectSafe` cannot be made into an object
-   |
-   = note: method `eq` references the `Self` type in its arguments or return type
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/did_you_mean/issue-40006.stderr b/src/test/ui/did_you_mean/issue-40006.stderr
index 87e48cd1e1c..5b384045a48 100644
--- a/src/test/ui/did_you_mean/issue-40006.stderr
+++ b/src/test/ui/did_you_mean/issue-40006.stderr
@@ -61,8 +61,9 @@ error[E0038]: the trait `X` cannot be made into an object
    |
 LL | impl dyn X {
    |      ^^^^^ the trait `X` cannot be made into an object
-   |
-   = note: method `xxx` has no receiver
+...
+LL |     fn xxx() { ### }
+   |        --- associated function `xxx` has no `self` parameter
 
 error: aborting due to 9 previous errors
 
diff --git a/src/test/ui/error-codes/E0033-teach.rs b/src/test/ui/error-codes/E0033-teach.rs
index 6a27b07fa8b..19439651394 100644
--- a/src/test/ui/error-codes/E0033-teach.rs
+++ b/src/test/ui/error-codes/E0033-teach.rs
@@ -1,14 +1,13 @@
 // compile-flags: -Z teach
 
 trait SomeTrait {
-    fn foo();
+    fn foo(); //~ associated function `foo` has no `self` parameter
 }
 
 fn main() {
     let trait_obj: &dyn SomeTrait = SomeTrait;
     //~^ ERROR expected value, found trait `SomeTrait`
     //~| ERROR E0038
-    //~| method `foo` has no receiver
 
     let &invalid = trait_obj;
     //~^ ERROR E0033
diff --git a/src/test/ui/error-codes/E0033-teach.stderr b/src/test/ui/error-codes/E0033-teach.stderr
index fb630de7fc1..80f3d4441bd 100644
--- a/src/test/ui/error-codes/E0033-teach.stderr
+++ b/src/test/ui/error-codes/E0033-teach.stderr
@@ -7,13 +7,14 @@ LL |     let trait_obj: &dyn SomeTrait = SomeTrait;
 error[E0038]: the trait `SomeTrait` cannot be made into an object
   --> $DIR/E0033-teach.rs:8:20
    |
+LL |     fn foo();
+   |        --- associated function `foo` has no `self` parameter
+...
 LL |     let trait_obj: &dyn SomeTrait = SomeTrait;
    |                    ^^^^^^^^^^^^^^ the trait `SomeTrait` cannot be made into an object
-   |
-   = note: method `foo` has no receiver
 
 error[E0033]: type `&dyn SomeTrait` cannot be dereferenced
-  --> $DIR/E0033-teach.rs:13:9
+  --> $DIR/E0033-teach.rs:12:9
    |
 LL |     let &invalid = trait_obj;
    |         ^^^^^^^^ type `&dyn SomeTrait` cannot be dereferenced
diff --git a/src/test/ui/error-codes/E0033.rs b/src/test/ui/error-codes/E0033.rs
index 582600e110b..e5f0530f45f 100644
--- a/src/test/ui/error-codes/E0033.rs
+++ b/src/test/ui/error-codes/E0033.rs
@@ -1,12 +1,11 @@
 trait SomeTrait {
-    fn foo();
+    fn foo(); //~ associated function `foo` has no `self` parameter
 }
 
 fn main() {
     let trait_obj: &dyn SomeTrait = SomeTrait;
     //~^ ERROR expected value, found trait `SomeTrait`
     //~| ERROR E0038
-    //~| method `foo` has no receiver
 
     let &invalid = trait_obj;
     //~^ ERROR E0033
diff --git a/src/test/ui/error-codes/E0033.stderr b/src/test/ui/error-codes/E0033.stderr
index fe9f45d86a6..c2843796cc8 100644
--- a/src/test/ui/error-codes/E0033.stderr
+++ b/src/test/ui/error-codes/E0033.stderr
@@ -7,13 +7,14 @@ LL |     let trait_obj: &dyn SomeTrait = SomeTrait;
 error[E0038]: the trait `SomeTrait` cannot be made into an object
   --> $DIR/E0033.rs:6:20
    |
+LL |     fn foo();
+   |        --- associated function `foo` has no `self` parameter
+...
 LL |     let trait_obj: &dyn SomeTrait = SomeTrait;
    |                    ^^^^^^^^^^^^^^ the trait `SomeTrait` cannot be made into an object
-   |
-   = note: method `foo` has no receiver
 
 error[E0033]: type `&dyn SomeTrait` cannot be dereferenced
-  --> $DIR/E0033.rs:11:9
+  --> $DIR/E0033.rs:10:9
    |
 LL |     let &invalid = trait_obj;
    |         ^^^^^^^^ type `&dyn SomeTrait` cannot be dereferenced
diff --git a/src/test/ui/error-codes/E0038.stderr b/src/test/ui/error-codes/E0038.stderr
index e3d7593e42a..5c4d6d53c46 100644
--- a/src/test/ui/error-codes/E0038.stderr
+++ b/src/test/ui/error-codes/E0038.stderr
@@ -1,10 +1,11 @@
 error[E0038]: the trait `Trait` cannot be made into an object
   --> $DIR/E0038.rs:5:1
    |
+LL |     fn foo(&self) -> Self;
+   |        --- method `foo` references the `Self` type in its parameters or return type
+...
 LL | fn call_foo(x: Box<dyn Trait>) {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Trait` cannot be made into an object
-   |
-   = note: method `foo` references the `Self` type in its arguments or return type
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/explicit/explicit-self-lifetime-mismatch.rs b/src/test/ui/explicit/explicit-self-lifetime-mismatch.rs
index 82c64bcf6a7..9ab8e13893b 100644
--- a/src/test/ui/explicit/explicit-self-lifetime-mismatch.rs
+++ b/src/test/ui/explicit/explicit-self-lifetime-mismatch.rs
@@ -6,11 +6,11 @@ struct Foo<'a,'b> {
 impl<'a,'b> Foo<'a,'b> {
     fn bar(self:
            Foo<'b,'a>
-    //~^ ERROR mismatched method receiver
+    //~^ ERROR mismatched `self` parameter type
     //~| expected type `Foo<'a, 'b>`
     //~| found type `Foo<'b, 'a>`
     //~| lifetime mismatch
-    //~| ERROR mismatched method receiver
+    //~| ERROR mismatched `self` parameter type
     //~| expected type `Foo<'a, 'b>`
     //~| found type `Foo<'b, 'a>`
     //~| lifetime mismatch
diff --git a/src/test/ui/explicit/explicit-self-lifetime-mismatch.stderr b/src/test/ui/explicit/explicit-self-lifetime-mismatch.stderr
index e6f9eded9a4..4bf2d573d4f 100644
--- a/src/test/ui/explicit/explicit-self-lifetime-mismatch.stderr
+++ b/src/test/ui/explicit/explicit-self-lifetime-mismatch.stderr
@@ -1,4 +1,4 @@
-error[E0308]: mismatched method receiver
+error[E0308]: mismatched `self` parameter type
   --> $DIR/explicit-self-lifetime-mismatch.rs:8:12
    |
 LL |            Foo<'b,'a>
@@ -17,7 +17,7 @@ note: ...does not necessarily outlive the lifetime 'a as defined on the impl at
 LL | impl<'a,'b> Foo<'a,'b> {
    |      ^^
 
-error[E0308]: mismatched method receiver
+error[E0308]: mismatched `self` parameter type
   --> $DIR/explicit-self-lifetime-mismatch.rs:8:12
    |
 LL |            Foo<'b,'a>
diff --git a/src/test/ui/issues/issue-17740.rs b/src/test/ui/issues/issue-17740.rs
index c131b895849..b47568400c3 100644
--- a/src/test/ui/issues/issue-17740.rs
+++ b/src/test/ui/issues/issue-17740.rs
@@ -4,11 +4,11 @@ struct Foo<'a> {
 
 impl <'a> Foo<'a>{
     fn bar(self: &mut Foo) {
-    //~^ mismatched method receiver
+    //~^ mismatched `self` parameter type
     //~| expected type `Foo<'a>`
     //~| found type `Foo<'_>`
     //~| lifetime mismatch
-    //~| mismatched method receiver
+    //~| mismatched `self` parameter type
     //~| expected type `Foo<'a>`
     //~| found type `Foo<'_>`
     //~| lifetime mismatch
diff --git a/src/test/ui/issues/issue-17740.stderr b/src/test/ui/issues/issue-17740.stderr
index 7ab0fa4d818..b8a0a067631 100644
--- a/src/test/ui/issues/issue-17740.stderr
+++ b/src/test/ui/issues/issue-17740.stderr
@@ -1,4 +1,4 @@
-error[E0308]: mismatched method receiver
+error[E0308]: mismatched `self` parameter type
   --> $DIR/issue-17740.rs:6:18
    |
 LL |     fn bar(self: &mut Foo) {
@@ -23,7 +23,7 @@ note: ...does not necessarily outlive the lifetime 'a as defined on the impl at
 LL | impl <'a> Foo<'a>{
    |       ^^
 
-error[E0308]: mismatched method receiver
+error[E0308]: mismatched `self` parameter type
   --> $DIR/issue-17740.rs:6:18
    |
 LL |     fn bar(self: &mut Foo) {
diff --git a/src/test/ui/issues/issue-17905-2.rs b/src/test/ui/issues/issue-17905-2.rs
index 259d9450189..44279cc867b 100644
--- a/src/test/ui/issues/issue-17905-2.rs
+++ b/src/test/ui/issues/issue-17905-2.rs
@@ -6,8 +6,8 @@ impl Pair<
     isize
 > {
     fn say(self: &Pair<&str, isize>) {
-//~^ ERROR mismatched method receiver
-//~| ERROR mismatched method receiver
+//~^ ERROR mismatched `self` parameter type
+//~| ERROR mismatched `self` parameter type
         println!("{:?}", self);
     }
 }
diff --git a/src/test/ui/issues/issue-17905-2.stderr b/src/test/ui/issues/issue-17905-2.stderr
index e3909e0c125..585bc9c1488 100644
--- a/src/test/ui/issues/issue-17905-2.stderr
+++ b/src/test/ui/issues/issue-17905-2.stderr
@@ -1,4 +1,4 @@
-error[E0308]: mismatched method receiver
+error[E0308]: mismatched `self` parameter type
   --> $DIR/issue-17905-2.rs:8:18
    |
 LL |     fn say(self: &Pair<&str, isize>) {
@@ -21,7 +21,7 @@ note: ...does not necessarily outlive the lifetime '_ as defined on the impl at
 LL |     &str,
    |     ^
 
-error[E0308]: mismatched method receiver
+error[E0308]: mismatched `self` parameter type
   --> $DIR/issue-17905-2.rs:8:18
    |
 LL |     fn say(self: &Pair<&str, isize>) {
diff --git a/src/test/ui/issues/issue-18959.stderr b/src/test/ui/issues/issue-18959.stderr
index 63c33b7f447..d5e7092801e 100644
--- a/src/test/ui/issues/issue-18959.stderr
+++ b/src/test/ui/issues/issue-18959.stderr
@@ -1,10 +1,11 @@
 error[E0038]: the trait `Bar` cannot be made into an object
   --> $DIR/issue-18959.rs:11:1
    |
+LL | pub trait Foo { fn foo<T>(&self, ext_thing: &T); }
+   |                    --- method `foo` has generic type parameters
+...
 LL | fn foo(b: &dyn Bar) {
    | ^^^^^^^^^^^^^^^^^^^ the trait `Bar` cannot be made into an object
-   |
-   = note: method `foo` has generic type parameters
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-19380.stderr b/src/test/ui/issues/issue-19380.stderr
index 27e3ff57bf9..92bfdf1f26e 100644
--- a/src/test/ui/issues/issue-19380.stderr
+++ b/src/test/ui/issues/issue-19380.stderr
@@ -1,10 +1,11 @@
 error[E0038]: the trait `Qiz` cannot be made into an object
   --> $DIR/issue-19380.rs:11:3
    |
+LL |   fn qiz();
+   |      --- associated function `qiz` has no `self` parameter
+...
 LL |   foos: &'static [&'static (dyn Qiz + 'static)]
    |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Qiz` cannot be made into an object
-   |
-   = note: method `qiz` has no receiver
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-19538.stderr b/src/test/ui/issues/issue-19538.stderr
index e5da0a9b0da..5415a45f7d6 100644
--- a/src/test/ui/issues/issue-19538.stderr
+++ b/src/test/ui/issues/issue-19538.stderr
@@ -1,18 +1,21 @@
 error[E0038]: the trait `Bar` cannot be made into an object
   --> $DIR/issue-19538.rs:17:15
    |
+LL |     fn foo<T>(&self, val: T);
+   |        --- method `foo` has generic type parameters
+...
 LL |     let test: &mut dyn Bar = &mut thing;
    |               ^^^^^^^^^^^^ the trait `Bar` cannot be made into an object
-   |
-   = note: method `foo` has generic type parameters
 
 error[E0038]: the trait `Bar` cannot be made into an object
   --> $DIR/issue-19538.rs:17:30
    |
+LL |     fn foo<T>(&self, val: T);
+   |        --- method `foo` has generic type parameters
+...
 LL |     let test: &mut dyn Bar = &mut thing;
    |                              ^^^^^^^^^^ the trait `Bar` cannot be made into an object
    |
-   = note: method `foo` has generic type parameters
    = note: required because of the requirements on the impl of `std::ops::CoerceUnsized<&mut dyn Bar>` for `&mut Thing`
 
 error: aborting due to 2 previous errors
diff --git a/src/test/ui/issues/issue-50781.stderr b/src/test/ui/issues/issue-50781.stderr
index c98f78c51ee..02475ea97e3 100644
--- a/src/test/ui/issues/issue-50781.stderr
+++ b/src/test/ui/issues/issue-50781.stderr
@@ -1,8 +1,8 @@
 error: the trait `X` cannot be made into an object
-  --> $DIR/issue-50781.rs:6:5
+  --> $DIR/issue-50781.rs:6:8
    |
 LL |     fn foo(&self) where Self: Trait;
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |        ^^^
    |
 note: lint level defined here
   --> $DIR/issue-50781.rs:1:9
diff --git a/src/test/ui/issues/issue-56806.rs b/src/test/ui/issues/issue-56806.rs
index b6454e578e6..b1dac26d65a 100644
--- a/src/test/ui/issues/issue-56806.rs
+++ b/src/test/ui/issues/issue-56806.rs
@@ -1,7 +1,6 @@
 pub trait Trait {
     fn dyn_instead_of_self(self: Box<dyn Trait>);
-    //~^ ERROR invalid method receiver type: std::boxed::Box<(dyn Trait + 'static)>
+    //~^ ERROR invalid `self` parameter type
 }
 
-pub fn main() {
-}
+pub fn main() {}
diff --git a/src/test/ui/issues/issue-56806.stderr b/src/test/ui/issues/issue-56806.stderr
index fae6a26720f..a4f9aadcfef 100644
--- a/src/test/ui/issues/issue-56806.stderr
+++ b/src/test/ui/issues/issue-56806.stderr
@@ -1,11 +1,12 @@
-error[E0307]: invalid method receiver type: std::boxed::Box<(dyn Trait + 'static)>
+error[E0307]: invalid `self` parameter type: std::boxed::Box<(dyn Trait + 'static)>
   --> $DIR/issue-56806.rs:2:34
    |
 LL |     fn dyn_instead_of_self(self: Box<dyn Trait>);
    |                                  ^^^^^^^^^^^^^^
    |
-   = note: type must be `Self` or a type that dereferences to it
+   = note: type of `self` must be `Self` or a type that dereferences to it
    = help: consider changing to `self`, `&self`, `&mut self`, `self: Box<Self>`, `self: Rc<Self>`, `self: Arc<Self>`, or `self: Pin<P>` (where P is one of the previous types except `Self`)
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0307`.
diff --git a/src/test/ui/object-safety/object-safety-associated-consts.stderr b/src/test/ui/object-safety/object-safety-associated-consts.stderr
index 55f9e3f9f13..7d5aa00356e 100644
--- a/src/test/ui/object-safety/object-safety-associated-consts.stderr
+++ b/src/test/ui/object-safety/object-safety-associated-consts.stderr
@@ -1,10 +1,11 @@
 error[E0038]: the trait `Bar` cannot be made into an object
   --> $DIR/object-safety-associated-consts.rs:9:1
    |
+LL |     const X: usize;
+   |           - the trait cannot contain associated consts like `X`
+...
 LL | fn make_bar<T:Bar>(t: &T) -> &dyn Bar {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Bar` cannot be made into an object
-   |
-   = note: the trait cannot contain associated consts like `X`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/object-safety/object-safety-generics.stderr b/src/test/ui/object-safety/object-safety-generics.stderr
index d66cdb98448..b25e0052e41 100644
--- a/src/test/ui/object-safety/object-safety-generics.stderr
+++ b/src/test/ui/object-safety/object-safety-generics.stderr
@@ -1,18 +1,20 @@
 error[E0038]: the trait `Bar` cannot be made into an object
   --> $DIR/object-safety-generics.rs:14:1
    |
+LL |     fn bar<T>(&self, t: T);
+   |        --- method `bar` has generic type parameters
+...
 LL | fn make_bar<T:Bar>(t: &T) -> &dyn Bar {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Bar` cannot be made into an object
-   |
-   = note: method `bar` has generic type parameters
 
 error[E0038]: the trait `Bar` cannot be made into an object
   --> $DIR/object-safety-generics.rs:19:1
    |
+LL |     fn bar<T>(&self, t: T);
+   |        --- method `bar` has generic type parameters
+...
 LL | fn make_bar_explicit<T:Bar>(t: &T) -> &dyn Bar {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Bar` cannot be made into an object
-   |
-   = note: method `bar` has generic type parameters
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/object-safety/object-safety-mentions-Self.stderr b/src/test/ui/object-safety/object-safety-mentions-Self.stderr
index c0c471c2b1e..971e79cb021 100644
--- a/src/test/ui/object-safety/object-safety-mentions-Self.stderr
+++ b/src/test/ui/object-safety/object-safety-mentions-Self.stderr
@@ -1,18 +1,20 @@
 error[E0038]: the trait `Bar` cannot be made into an object
   --> $DIR/object-safety-mentions-Self.rs:17:1
    |
+LL |     fn bar(&self, x: &Self);
+   |        --- method `bar` references the `Self` type in its parameters or return type
+...
 LL | fn make_bar<T:Bar>(t: &T) -> &dyn Bar {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Bar` cannot be made into an object
-   |
-   = note: method `bar` references the `Self` type in its arguments or return type
 
 error[E0038]: the trait `Baz` cannot be made into an object
   --> $DIR/object-safety-mentions-Self.rs:22:1
    |
+LL |     fn bar(&self) -> Self;
+   |        --- method `bar` references the `Self` type in its parameters or return type
+...
 LL | fn make_baz<T:Baz>(t: &T) -> &dyn Baz {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Baz` cannot be made into an object
-   |
-   = note: method `bar` references the `Self` type in its arguments or return type
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/object-safety/object-safety-no-static.stderr b/src/test/ui/object-safety/object-safety-no-static.stderr
index da8dd657c2a..0de783f60ea 100644
--- a/src/test/ui/object-safety/object-safety-no-static.stderr
+++ b/src/test/ui/object-safety/object-safety-no-static.stderr
@@ -1,10 +1,11 @@
 error[E0038]: the trait `Foo` cannot be made into an object
   --> $DIR/object-safety-no-static.rs:8:1
    |
+LL |     fn foo();
+   |        --- associated function `foo` has no `self` parameter
+...
 LL | fn foo_implicit<T:Foo+'static>(b: Box<T>) -> Box<dyn Foo + 'static> {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Foo` cannot be made into an object
-   |
-   = note: method `foo` has no receiver
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/resolve/issue-3907-2.stderr b/src/test/ui/resolve/issue-3907-2.stderr
index 968c1f3e463..63ac11dc8ae 100644
--- a/src/test/ui/resolve/issue-3907-2.stderr
+++ b/src/test/ui/resolve/issue-3907-2.stderr
@@ -4,7 +4,7 @@ error[E0038]: the trait `issue_3907::Foo` cannot be made into an object
 LL | fn bar(_x: Foo) {}
    | ^^^^^^^^^^^^^^^ the trait `issue_3907::Foo` cannot be made into an object
    |
-   = note: method `bar` has no receiver
+   = note: associated function `bar` has no `self` parameter
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/self/arbitrary-self-types-not-object-safe.stderr b/src/test/ui/self/arbitrary-self-types-not-object-safe.stderr
index e45bc2657f1..e6eba377a95 100644
--- a/src/test/ui/self/arbitrary-self-types-not-object-safe.stderr
+++ b/src/test/ui/self/arbitrary-self-types-not-object-safe.stderr
@@ -1,18 +1,21 @@
 error[E0038]: the trait `Foo` cannot be made into an object
   --> $DIR/arbitrary-self-types-not-object-safe.rs:31:32
    |
+LL |     fn foo(self: &Rc<Self>) -> usize;
+   |        --- method `foo`'s `self` parameter cannot be dispatched on
+...
 LL |     let x = Rc::new(5usize) as Rc<dyn Foo>;
    |                                ^^^^^^^^^^^ the trait `Foo` cannot be made into an object
-   |
-   = note: method `foo`'s receiver cannot be dispatched on
 
 error[E0038]: the trait `Foo` cannot be made into an object
   --> $DIR/arbitrary-self-types-not-object-safe.rs:31:13
    |
+LL |     fn foo(self: &Rc<Self>) -> usize;
+   |        --- method `foo`'s `self` parameter cannot be dispatched on
+...
 LL |     let x = Rc::new(5usize) as Rc<dyn Foo>;
    |             ^^^^^^^^^^^^^^^ the trait `Foo` cannot be made into an object
    |
-   = note: method `foo`'s receiver cannot be dispatched on
    = note: required because of the requirements on the impl of `std::ops::CoerceUnsized<std::rc::Rc<dyn Foo>>` for `std::rc::Rc<usize>`
 
 error: aborting due to 2 previous errors
diff --git a/src/test/ui/span/issue-27522.rs b/src/test/ui/span/issue-27522.rs
index 5c9893f64a6..7a0cfb679ed 100644
--- a/src/test/ui/span/issue-27522.rs
+++ b/src/test/ui/span/issue-27522.rs
@@ -3,7 +3,7 @@
 struct SomeType {}
 
 trait Foo {
-    fn handler(self: &SomeType); //~ ERROR invalid method receiver type
+    fn handler(self: &SomeType); //~ ERROR invalid `self` parameter type
 }
 
 fn main() {}
diff --git a/src/test/ui/span/issue-27522.stderr b/src/test/ui/span/issue-27522.stderr
index 88dfee1cada..8a254a96855 100644
--- a/src/test/ui/span/issue-27522.stderr
+++ b/src/test/ui/span/issue-27522.stderr
@@ -1,11 +1,12 @@
-error[E0307]: invalid method receiver type: &SomeType
+error[E0307]: invalid `self` parameter type: &SomeType
   --> $DIR/issue-27522.rs:6:22
    |
 LL |     fn handler(self: &SomeType);
    |                      ^^^^^^^^^
    |
-   = note: type must be `Self` or a type that dereferences to it
+   = note: type of `self` must be `Self` or a type that dereferences to it
    = help: consider changing to `self`, `&self`, `&mut self`, `self: Box<Self>`, `self: Rc<Self>`, `self: Arc<Self>`, or `self: Pin<P>` (where P is one of the previous types except `Self`)
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0307`.
diff --git a/src/test/ui/traits/trait-item-privacy.stderr b/src/test/ui/traits/trait-item-privacy.stderr
index ce2919c8e77..16ea7bdb080 100644
--- a/src/test/ui/traits/trait-item-privacy.stderr
+++ b/src/test/ui/traits/trait-item-privacy.stderr
@@ -110,12 +110,17 @@ LL |     C::A;
 error[E0038]: the trait `assoc_const::C` cannot be made into an object
   --> $DIR/trait-item-privacy.rs:101:5
    |
+LL |         const A: u8 = 0;
+   |               - the trait cannot contain associated consts like `A`
+...
+LL |         const B: u8 = 0;
+   |               - the trait cannot contain associated consts like `B`
+...
+LL |         const C: u8 = 0;
+   |               - the trait cannot contain associated consts like `C`
+...
 LL |     C::A;
    |     ^^^^ the trait `assoc_const::C` cannot be made into an object
-   |
-   = note: the trait cannot contain associated consts like `C`
-   = note: the trait cannot contain associated consts like `B`
-   = note: the trait cannot contain associated consts like `A`
 
 error[E0223]: ambiguous associated type
   --> $DIR/trait-item-privacy.rs:115:12
diff --git a/src/test/ui/traits/trait-object-safety.stderr b/src/test/ui/traits/trait-object-safety.stderr
index 68edc178705..3ac1e96b30c 100644
--- a/src/test/ui/traits/trait-object-safety.stderr
+++ b/src/test/ui/traits/trait-object-safety.stderr
@@ -1,19 +1,22 @@
 error[E0038]: the trait `Tr` cannot be made into an object
   --> $DIR/trait-object-safety.rs:15:22
    |
+LL |     fn foo();
+   |        --- associated function `foo` has no `self` parameter
+...
 LL |     let _: &dyn Tr = &St;
    |                      ^^^ the trait `Tr` cannot be made into an object
    |
-   = note: method `foo` has no receiver
    = note: required because of the requirements on the impl of `std::ops::CoerceUnsized<&dyn Tr>` for `&St`
 
 error[E0038]: the trait `Tr` cannot be made into an object
   --> $DIR/trait-object-safety.rs:15:12
    |
+LL |     fn foo();
+   |        --- associated function `foo` has no `self` parameter
+...
 LL |     let _: &dyn Tr = &St;
    |            ^^^^^^^ the trait `Tr` cannot be made into an object
-   |
-   = note: method `foo` has no receiver
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/traits/trait-test-2.stderr b/src/test/ui/traits/trait-test-2.stderr
index 5d5251925a1..83c2c065274 100644
--- a/src/test/ui/traits/trait-test-2.stderr
+++ b/src/test/ui/traits/trait-test-2.stderr
@@ -13,20 +13,25 @@ LL |     10.blah::<i32, i32>();
 error[E0038]: the trait `bar` cannot be made into an object
   --> $DIR/trait-test-2.rs:11:16
    |
+LL | trait bar { fn dup(&self) -> Self; fn blah<X>(&self); }
+   |                ---                    ---- method `blah` has generic type parameters
+   |                |
+   |                method `dup` references the `Self` type in its parameters or return type
+...
 LL |     (box 10 as Box<dyn bar>).dup();
    |                ^^^^^^^^^^^^ the trait `bar` cannot be made into an object
-   |
-   = note: method `dup` references the `Self` type in its arguments or return type
-   = note: method `blah` has generic type parameters
 
 error[E0038]: the trait `bar` cannot be made into an object
   --> $DIR/trait-test-2.rs:11:6
    |
+LL | trait bar { fn dup(&self) -> Self; fn blah<X>(&self); }
+   |                ---                    ---- method `blah` has generic type parameters
+   |                |
+   |                method `dup` references the `Self` type in its parameters or return type
+...
 LL |     (box 10 as Box<dyn bar>).dup();
    |      ^^^^^^ the trait `bar` cannot be made into an object
    |
-   = note: method `dup` references the `Self` type in its arguments or return type
-   = note: method `blah` has generic type parameters
    = note: required because of the requirements on the impl of `std::ops::CoerceUnsized<std::boxed::Box<dyn bar>>` for `std::boxed::Box<{integer}>`
 
 error: aborting due to 4 previous errors
diff --git a/src/test/ui/type/type-parameter-defaults-referencing-Self-ppaux.stderr b/src/test/ui/type/type-parameter-defaults-referencing-Self-ppaux.stderr
index 58727ea0fef..b315fe9df8a 100644
--- a/src/test/ui/type/type-parameter-defaults-referencing-Self-ppaux.stderr
+++ b/src/test/ui/type/type-parameter-defaults-referencing-Self-ppaux.stderr
@@ -13,10 +13,11 @@ LL |     let y = x as dyn MyAdd<i32>;
 error[E0038]: the trait `MyAdd` cannot be made into an object
   --> $DIR/type-parameter-defaults-referencing-Self-ppaux.rs:14:18
    |
+LL | trait MyAdd<Rhs=Self> { fn add(&self, other: &Rhs) -> Self; }
+   |                            --- method `add` references the `Self` type in its parameters or return type
+...
 LL |     let y = x as dyn MyAdd<i32>;
    |                  ^^^^^^^^^^^^^^ the trait `MyAdd` cannot be made into an object
-   |
-   = note: method `add` references the `Self` type in its arguments or return type
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/ufcs/ufcs-explicit-self-bad.rs b/src/test/ui/ufcs/ufcs-explicit-self-bad.rs
index c6ff94a5e76..bdb8e197fbe 100644
--- a/src/test/ui/ufcs/ufcs-explicit-self-bad.rs
+++ b/src/test/ui/ufcs/ufcs-explicit-self-bad.rs
@@ -6,7 +6,7 @@ struct Foo {
 
 impl Foo {
     fn foo(self: isize, x: isize) -> isize {
-        //~^ ERROR invalid method receiver type
+        //~^ ERROR invalid `self` parameter type
         self.f + x
     }
 }
@@ -17,11 +17,11 @@ struct Bar<T> {
 
 impl<T> Bar<T> {
     fn foo(self: Bar<isize>, x: isize) -> isize {
-        //~^ ERROR invalid method receiver type
+        //~^ ERROR invalid `self` parameter type
         x
     }
     fn bar(self: &Bar<usize>, x: isize) -> isize {
-        //~^ ERROR invalid method receiver type
+        //~^ ERROR invalid `self` parameter type
         x
     }
 }
@@ -34,14 +34,14 @@ trait SomeTrait {
 
 impl<'a, T> SomeTrait for &'a Bar<T> {
     fn dummy1(self: &&'a Bar<T>) { }
-    fn dummy2(self: &Bar<T>) {} //~ ERROR mismatched method receiver
-    //~^ ERROR mismatched method receiver
+    fn dummy2(self: &Bar<T>) {} //~ ERROR mismatched `self` parameter type
+    //~^ ERROR mismatched `self` parameter type
     fn dummy3(self: &&Bar<T>) {}
-    //~^ ERROR mismatched method receiver
+    //~^ ERROR mismatched `self` parameter type
     //~| expected type `&'a Bar<T>`
     //~| found type `&Bar<T>`
     //~| lifetime mismatch
-    //~| ERROR mismatched method receiver
+    //~| ERROR mismatched `self` parameter type
     //~| expected type `&'a Bar<T>`
     //~| found type `&Bar<T>`
     //~| lifetime mismatch
diff --git a/src/test/ui/ufcs/ufcs-explicit-self-bad.stderr b/src/test/ui/ufcs/ufcs-explicit-self-bad.stderr
index 6da20e37577..b2fe1b281fc 100644
--- a/src/test/ui/ufcs/ufcs-explicit-self-bad.stderr
+++ b/src/test/ui/ufcs/ufcs-explicit-self-bad.stderr
@@ -1,31 +1,31 @@
-error[E0307]: invalid method receiver type: isize
+error[E0307]: invalid `self` parameter type: isize
   --> $DIR/ufcs-explicit-self-bad.rs:8:18
    |
 LL |     fn foo(self: isize, x: isize) -> isize {
    |                  ^^^^^
    |
-   = note: type must be `Self` or a type that dereferences to it
+   = note: type of `self` must be `Self` or a type that dereferences to it
    = help: consider changing to `self`, `&self`, `&mut self`, `self: Box<Self>`, `self: Rc<Self>`, `self: Arc<Self>`, or `self: Pin<P>` (where P is one of the previous types except `Self`)
 
-error[E0307]: invalid method receiver type: Bar<isize>
+error[E0307]: invalid `self` parameter type: Bar<isize>
   --> $DIR/ufcs-explicit-self-bad.rs:19:18
    |
 LL |     fn foo(self: Bar<isize>, x: isize) -> isize {
    |                  ^^^^^^^^^^
    |
-   = note: type must be `Self` or a type that dereferences to it
+   = note: type of `self` must be `Self` or a type that dereferences to it
    = help: consider changing to `self`, `&self`, `&mut self`, `self: Box<Self>`, `self: Rc<Self>`, `self: Arc<Self>`, or `self: Pin<P>` (where P is one of the previous types except `Self`)
 
-error[E0307]: invalid method receiver type: &Bar<usize>
+error[E0307]: invalid `self` parameter type: &Bar<usize>
   --> $DIR/ufcs-explicit-self-bad.rs:23:18
    |
 LL |     fn bar(self: &Bar<usize>, x: isize) -> isize {
    |                  ^^^^^^^^^^^
    |
-   = note: type must be `Self` or a type that dereferences to it
+   = note: type of `self` must be `Self` or a type that dereferences to it
    = help: consider changing to `self`, `&self`, `&mut self`, `self: Box<Self>`, `self: Rc<Self>`, `self: Arc<Self>`, or `self: Pin<P>` (where P is one of the previous types except `Self`)
 
-error[E0308]: mismatched method receiver
+error[E0308]: mismatched `self` parameter type
   --> $DIR/ufcs-explicit-self-bad.rs:37:21
    |
 LL |     fn dummy2(self: &Bar<T>) {}
@@ -44,7 +44,7 @@ note: ...does not necessarily outlive the lifetime 'a as defined on the impl at
 LL | impl<'a, T> SomeTrait for &'a Bar<T> {
    |      ^^
 
-error[E0308]: mismatched method receiver
+error[E0308]: mismatched `self` parameter type
   --> $DIR/ufcs-explicit-self-bad.rs:37:21
    |
 LL |     fn dummy2(self: &Bar<T>) {}
@@ -63,7 +63,7 @@ note: ...does not necessarily outlive the anonymous lifetime #1 defined on the m
 LL |     fn dummy2(self: &Bar<T>) {}
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error[E0308]: mismatched method receiver
+error[E0308]: mismatched `self` parameter type
   --> $DIR/ufcs-explicit-self-bad.rs:39:21
    |
 LL |     fn dummy3(self: &&Bar<T>) {}
@@ -82,7 +82,7 @@ note: ...does not necessarily outlive the lifetime 'a as defined on the impl at
 LL | impl<'a, T> SomeTrait for &'a Bar<T> {
    |      ^^
 
-error[E0308]: mismatched method receiver
+error[E0308]: mismatched `self` parameter type
   --> $DIR/ufcs-explicit-self-bad.rs:39:21
    |
 LL |     fn dummy3(self: &&Bar<T>) {}
@@ -103,4 +103,5 @@ LL |     fn dummy3(self: &&Bar<T>) {}
 
 error: aborting due to 7 previous errors
 
-For more information about this error, try `rustc --explain E0308`.
+Some errors have detailed explanations: E0307, E0308.
+For more information about an error, try `rustc --explain E0307`.
diff --git a/src/test/ui/wf/wf-object-safe.stderr b/src/test/ui/wf/wf-object-safe.stderr
index 3b264ecd580..0d8441f87e7 100644
--- a/src/test/ui/wf/wf-object-safe.stderr
+++ b/src/test/ui/wf/wf-object-safe.stderr
@@ -1,10 +1,11 @@
 error[E0038]: the trait `A` cannot be made into an object
   --> $DIR/wf-object-safe.rs:9:13
    |
+LL |     fn foo(&self, _x: &Self);
+   |        --- method `foo` references the `Self` type in its parameters or return type
+...
 LL |     let _x: &dyn A;
    |             ^^^^^^ the trait `A` cannot be made into an object
-   |
-   = note: method `foo` references the `Self` type in its arguments or return type
 
 error: aborting due to previous error