Arbitrary self types v2: adjust diagnostic.

The recently landed PR to adjust arbitrary self types was a bit
overenthusiastic, advising folks to use the new Receiver trait even
before it's been stabilized. Revert to the older wording of the lint in
such cases.

Author: adetaylor

compiler/rustc_hir_analysis/messages.ftl

@@ -246,6 +246,12 @@ hir_analysis_invalid_receiver_ty = invalid `self` parameter type: `{$receiver_ty
 hir_analysis_invalid_receiver_ty_help =
     consider changing to `self`, `&self`, `&mut self`, or a type implementing `Receiver` such as `self: Box<Self>`, `self: Rc<Self>`, or `self: Arc<Self>`
 
+hir_analysis_invalid_receiver_ty_help_no_arbitrary_self_types =
+    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`)
+
+hir_analysis_invalid_receiver_ty_no_arbitrary_self_types = invalid `self` parameter type: `{$receiver_ty}`
+    .note = type of `self` must be `Self` or a type that dereferences to it
+
 hir_analysis_invalid_union_field =
     field must implement `Copy` or be wrapped in `ManuallyDrop<...>` to be used in a union
     .note = union fields must not have drop side-effects, which is currently enforced via either `Copy` or `ManuallyDrop<...>`

compiler/rustc_hir_analysis/src/check/wfcheck.rs

@@ -1748,9 +1748,15 @@ fn check_method_receiver<'tcx>(
             // Report error; would not have worked with `arbitrary_self_types[_pointers]`.
             {
                 match receiver_validity_err {
-                    ReceiverValidityError::DoesNotDeref => {
+                    ReceiverValidityError::DoesNotDeref if arbitrary_self_types_level.is_some() => {
                         tcx.dcx().emit_err(errors::InvalidReceiverTy { span, receiver_ty })
                     }
+                    ReceiverValidityError::DoesNotDeref => {
+                        tcx.dcx().emit_err(errors::InvalidReceiverTyNoArbitrarySelfTypes {
+                            span,
+                            receiver_ty,
+                        })
+                    }
                     ReceiverValidityError::MethodGenericParamUsed => {
                         tcx.dcx().emit_err(errors::InvalidGenericReceiverTy { span, receiver_ty })
                     }

compiler/rustc_hir_analysis/src/errors.rs

@@ -1655,6 +1655,16 @@ pub(crate) struct NonConstRange {
     pub span: Span,
 }
 
+#[derive(Diagnostic)]
+#[diag(hir_analysis_invalid_receiver_ty_no_arbitrary_self_types, code = E0307)]
+#[note]
+#[help(hir_analysis_invalid_receiver_ty_help_no_arbitrary_self_types)]
+pub(crate) struct InvalidReceiverTyNoArbitrarySelfTypes<'tcx> {
+    #[primary_span]
+    pub span: Span,
+    pub receiver_ty: Ty<'tcx>,
+}
+
 #[derive(Diagnostic)]
 #[diag(hir_analysis_invalid_receiver_ty, code = E0307)]
 #[note]

tests/ui/async-await/inference_var_self_argument.stderr

@@ -4,8 +4,8 @@ error[E0307]: invalid `self` parameter type: `&dyn Foo`
 LL |     async fn foo(self: &dyn Foo) {
    |                        ^^^^^^^^
    |
-   = note: type of `self` must be `Self` or some type implementing `Receiver`
-   = help: consider changing to `self`, `&self`, `&mut self`, or a type implementing `Receiver` such as `self: Box<Self>`, `self: Rc<Self>`, or `self: Arc<Self>`
+   = 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[E0038]: the trait `Foo` cannot be made into an object
   --> $DIR/inference_var_self_argument.rs:5:5

tests/ui/async-await/issue-66312.stderr

@@ -4,8 +4,8 @@ error[E0307]: invalid `self` parameter type: `T`
 LL |     fn is_some(self: T);
    |                      ^
    |
-   = note: type of `self` must be `Self` or some type implementing `Receiver`
-   = help: consider changing to `self`, `&self`, `&mut self`, or a type implementing `Receiver` such as `self: Box<Self>`, `self: Rc<Self>`, or `self: Arc<Self>`
+   = 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 types
   --> $DIR/issue-66312.rs:9:8

tests/ui/feature-gates/feature-gate-dispatch-from-dyn-cell.stderr

@@ -4,8 +4,8 @@ error[E0307]: invalid `self` parameter type: `Cell<&Self>`
 LL |     fn cell(self: Cell<&Self>);
    |                   ^^^^^^^^^^^
    |
-   = note: type of `self` must be `Self` or some type implementing `Receiver`
-   = help: consider changing to `self`, `&self`, `&mut self`, or a type implementing `Receiver` such as `self: Box<Self>`, `self: Rc<Self>`, or `self: Arc<Self>`
+   = 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 1 previous error
 

tests/ui/issues/issue-56806.stderr

@@ -4,8 +4,8 @@ error[E0307]: invalid `self` parameter type: `Box<(dyn Trait + 'static)>`
 LL |     fn dyn_instead_of_self(self: Box<dyn Trait>);
    |                                  ^^^^^^^^^^^^^^
    |
-   = note: type of `self` must be `Self` or some type implementing `Receiver`
-   = help: consider changing to `self`, `&self`, `&mut self`, or a type implementing `Receiver` such as `self: Box<Self>`, `self: Rc<Self>`, or `self: Arc<Self>`
+   = 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 1 previous error
 

tests/ui/self/arbitrary-self-opaque.stderr

@@ -4,8 +4,8 @@ error[E0307]: invalid `self` parameter type: `Bar`
 LL |     fn foo(self: Bar) {}
    |                  ^^^
    |
-   = note: type of `self` must be `Self` or some type implementing `Receiver`
-   = help: consider changing to `self`, `&self`, `&mut self`, or a type implementing `Receiver` such as `self: Box<Self>`, `self: Rc<Self>`, or `self: Arc<Self>`
+   = 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: item does not constrain `Bar::{opaque#0}`, but has it in its signature
   --> $DIR/arbitrary-self-opaque.rs:7:8

tests/ui/span/issue-27522.stderr

@@ -4,8 +4,8 @@ error[E0307]: invalid `self` parameter type: `&SomeType`
 LL |     fn handler(self: &SomeType);
    |                      ^^^^^^^^^
    |
-   = note: type of `self` must be `Self` or some type implementing `Receiver`
-   = help: consider changing to `self`, `&self`, `&mut self`, or a type implementing `Receiver` such as `self: Box<Self>`, `self: Rc<Self>`, or `self: Arc<Self>`
+   = 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 1 previous error
 

tests/ui/suggestions/dyn-incompatible-trait-should-use-where-sized.stderr

@@ -32,8 +32,8 @@ error[E0307]: invalid `self` parameter type: `()`
 LL |     fn bar(self: ()) {}
    |                  ^^
    |
-   = note: type of `self` must be `Self` or some type implementing `Receiver`
-   = help: consider changing to `self`, `&self`, `&mut self`, or a type implementing `Receiver` such as `self: Box<Self>`, `self: Rc<Self>`, or `self: Arc<Self>`
+   = 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 2 previous errors