Tweak spans for self arg, fix borrow suggestion for signature mismatch

compiler/rustc_ast/src/ast.rs

@@ -2353,7 +2353,12 @@ impl Param {
     /// Builds a `Param` object from `ExplicitSelf`.
     pub fn from_self(attrs: AttrVec, eself: ExplicitSelf, eself_ident: Ident) -> Param {
         let span = eself.span.to(eself_ident.span);
-        let infer_ty = P(Ty { id: DUMMY_NODE_ID, kind: TyKind::ImplicitSelf, span, tokens: None });
+        let infer_ty = P(Ty {
+            id: DUMMY_NODE_ID,
+            kind: TyKind::ImplicitSelf,
+            span: eself_ident.span,
+            tokens: None,
+        });
         let (mutbl, ty) = match eself.node {
             SelfKind::Explicit(ty, mutbl) => (mutbl, ty),
             SelfKind::Value(mutbl) => (mutbl, infer_ty),

compiler/rustc_trait_selection/messages.ftl

@@ -1,3 +1,13 @@
+trait_selection_adjust_signature_borrow = consider adjusting the signature so it borrows its {$len ->
+        [one] argument
+        *[other] arguments
+    }
+
+trait_selection_adjust_signature_remove_borrow = consider adjusting the signature so it does not borrow its {$len ->
+        [one] argument
+        *[other] arguments
+    }
+
 trait_selection_dump_vtable_entries = vtable entries for `{$trait_ref}`: {$entries}
 
 trait_selection_empty_on_clause_in_rustc_on_unimplemented = empty `on`-clause in `#[rustc_on_unimplemented]`

compiler/rustc_trait_selection/src/errors.rs

@@ -1,5 +1,8 @@
 use crate::fluent_generated as fluent;
-use rustc_errors::{ErrorGuaranteed, Handler, IntoDiagnostic};
+use rustc_errors::{
+    AddToDiagnostic, Applicability, Diagnostic, ErrorGuaranteed, Handler, IntoDiagnostic,
+    SubdiagnosticMessage,
+};
 use rustc_macros::Diagnostic;
 use rustc_middle::ty::{self, PolyTraitRef, Ty};
 use rustc_span::{Span, Symbol};
@@ -97,3 +100,34 @@ pub struct InherentProjectionNormalizationOverflow {
     pub span: Span,
     pub ty: String,
 }
+
+pub enum AdjustSignatureBorrow {
+    Borrow { to_borrow: Vec<(Span, String)> },
+    RemoveBorrow { remove_borrow: Vec<(Span, String)> },
+}
+
+impl AddToDiagnostic for AdjustSignatureBorrow {
+    fn add_to_diagnostic_with<F>(self, diag: &mut Diagnostic, _: F)
+    where
+        F: Fn(&mut Diagnostic, SubdiagnosticMessage) -> SubdiagnosticMessage,
+    {
+        match self {
+            AdjustSignatureBorrow::Borrow { to_borrow } => {
+                diag.set_arg("len", to_borrow.len());
+                diag.multipart_suggestion_verbose(
+                    fluent::trait_selection_adjust_signature_borrow,
+                    to_borrow,
+                    Applicability::MaybeIncorrect,
+                );
+            }
+            AdjustSignatureBorrow::RemoveBorrow { remove_borrow } => {
+                diag.set_arg("len", remove_borrow.len());
+                diag.multipart_suggestion_verbose(
+                    fluent::trait_selection_adjust_signature_remove_borrow,
+                    remove_borrow,
+                    Applicability::MaybeIncorrect,
+                );
+            }
+        }
+    }
+}

compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs

@@ -5,6 +5,7 @@ use super::{
     PredicateObligation,
 };
 
+use crate::errors;
 use crate::infer::InferCtxt;
 use crate::traits::{NormalizeExt, ObligationCtxt};
 
@@ -3959,6 +3960,10 @@ fn hint_missing_borrow<'tcx>(
     found_node: Node<'_>,
     err: &mut Diagnostic,
 ) {
+    if matches!(found_node, Node::TraitItem(..)) {
+        return;
+    }
+
     let found_args = match found.kind() {
         ty::FnPtr(f) => infcx.instantiate_binder_with_placeholders(*f).inputs().iter(),
         kind => {
@@ -4028,19 +4033,11 @@ fn hint_missing_borrow<'tcx>(
     }
 
     if !to_borrow.is_empty() {
-        err.multipart_suggestion_verbose(
-            "consider borrowing the argument",
-            to_borrow,
-            Applicability::MaybeIncorrect,
-        );
+        err.subdiagnostic(errors::AdjustSignatureBorrow::Borrow { to_borrow });
     }
 
     if !remove_borrow.is_empty() {
-        err.multipart_suggestion_verbose(
-            "do not borrow the argument",
-            remove_borrow,
-            Applicability::MaybeIncorrect,
-        );
+        err.subdiagnostic(errors::AdjustSignatureBorrow::RemoveBorrow { remove_borrow });
     }
 }
 

tests/ui/anonymous-higher-ranked-lifetime.stderr

@@ -13,7 +13,7 @@ note: required by a bound in `f1`
    |
 LL | fn f1<F>(_: F) where F: Fn(&(), &()) {}
    |                         ^^^^^^^^^^^^ required by this bound in `f1`
-help: consider borrowing the argument
+help: consider adjusting the signature so it borrows its arguments
    |
 LL |     f1(|_: &(), _: &()| {});
    |            +       +
@@ -33,7 +33,7 @@ note: required by a bound in `f2`
    |
 LL | fn f2<F>(_: F) where F: for<'a> Fn(&'a (), &()) {}
    |                         ^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `f2`
-help: consider borrowing the argument
+help: consider adjusting the signature so it borrows its arguments
    |
 LL |     f2(|_: &(), _: &()| {});
    |            +       +
@@ -53,7 +53,7 @@ note: required by a bound in `f3`
    |
 LL | fn f3<'a, F>(_: F) where F: Fn(&'a (), &()) {}
    |                             ^^^^^^^^^^^^^^^ required by this bound in `f3`
-help: consider borrowing the argument
+help: consider adjusting the signature so it borrows its arguments
    |
 LL |     f3(|_: &(), _: &()| {});
    |            +       +
@@ -73,7 +73,7 @@ note: required by a bound in `f4`
    |
 LL | fn f4<F>(_: F) where F: for<'r> Fn(&(), &'r ()) {}
    |                         ^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `f4`
-help: consider borrowing the argument
+help: consider adjusting the signature so it borrows its arguments
    |
 LL |     f4(|_: &(), _: &()| {});
    |            +       +
@@ -93,7 +93,7 @@ note: required by a bound in `f5`
    |
 LL | fn f5<F>(_: F) where F: for<'r> Fn(&'r (), &'r ()) {}
    |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `f5`
-help: consider borrowing the argument
+help: consider adjusting the signature so it borrows its arguments
    |
 LL |     f5(|_: &(), _: &()| {});
    |            +       +
@@ -113,7 +113,7 @@ note: required by a bound in `g1`
    |
 LL | fn g1<F>(_: F) where F: Fn(&(), Box<dyn Fn(&())>) {}
    |                         ^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `g1`
-help: consider borrowing the argument
+help: consider adjusting the signature so it borrows its argument
    |
 LL |     g1(|_: &(), _: ()| {});
    |            +
@@ -133,7 +133,7 @@ note: required by a bound in `g2`
    |
 LL | fn g2<F>(_: F) where F: Fn(&(), fn(&())) {}
    |                         ^^^^^^^^^^^^^^^^ required by this bound in `g2`
-help: consider borrowing the argument
+help: consider adjusting the signature so it borrows its argument
    |
 LL |     g2(|_: &(), _: ()| {});
    |            +
@@ -153,7 +153,7 @@ note: required by a bound in `g3`
    |
 LL | fn g3<F>(_: F) where F: for<'s> Fn(&'s (), Box<dyn Fn(&())>) {}
    |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `g3`
-help: consider borrowing the argument
+help: consider adjusting the signature so it borrows its argument
    |
 LL |     g3(|_: &(), _: ()| {});
    |            +
@@ -173,7 +173,7 @@ note: required by a bound in `g4`
    |
 LL | fn g4<F>(_: F) where F: Fn(&(), for<'r> fn(&'r ())) {}
    |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `g4`
-help: consider borrowing the argument
+help: consider adjusting the signature so it borrows its argument
    |
 LL |     g4(|_: &(), _: ()| {});
    |            +
@@ -193,7 +193,7 @@ note: required by a bound in `h1`
    |
 LL | fn h1<F>(_: F) where F: Fn(&(), Box<dyn Fn(&())>, &(), fn(&(), &())) {}
    |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `h1`
-help: consider borrowing the argument
+help: consider adjusting the signature so it borrows its arguments
    |
 LL |     h1(|_: &(), _: (), _: &(), _: ()| {});
    |            +              +
@@ -213,7 +213,7 @@ note: required by a bound in `h2`
    |
 LL | fn h2<F>(_: F) where F: for<'t0> Fn(&(), Box<dyn Fn(&())>, &'t0 (), fn(&(), &())) {}
    |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `h2`
-help: consider borrowing the argument
+help: consider adjusting the signature so it borrows its arguments
    |
 LL |     h2(|_: &(), _: (), _: &(), _: ()| {});
    |            +              +

tests/ui/closures/multiple-fn-bounds.stderr

@@ -18,7 +18,7 @@ note: required by a bound in `foo`
    |
 LL | fn foo<F: Fn(&char) -> bool + Fn(char) -> bool>(f: F) {
    |                               ^^^^^^^^^^^^^^^^ required by this bound in `foo`
-help: do not borrow the argument
+help: consider adjusting the signature so it does not borrow its argument
    |
 LL |     foo(move |char| v);
    |               ~~~~

tests/ui/dropck/explicit-drop-bounds.bad1.stderr

@@ -15,10 +15,10 @@ LL |     [T; 1]: Copy, T: std::marker::Copy // But `[T; 1]: Copy` does not imply
    |                 ~~~~~~~~~~~~~~~~~~~~~~
 
 error[E0277]: the trait bound `T: Copy` is not satisfied
-  --> $DIR/explicit-drop-bounds.rs:32:13
+  --> $DIR/explicit-drop-bounds.rs:32:18
    |
 LL |     fn drop(&mut self) {}
-   |             ^^^^^^^^^ the trait `Copy` is not implemented for `T`
+   |                  ^^^^ the trait `Copy` is not implemented for `T`
    |
 note: required by a bound in `DropMe`
   --> $DIR/explicit-drop-bounds.rs:7:18

tests/ui/dropck/explicit-drop-bounds.bad2.stderr

@@ -15,10 +15,10 @@ LL | impl<T: std::marker::Copy> Drop for DropMe<T>
    |       +++++++++++++++++++
 
 error[E0277]: the trait bound `T: Copy` is not satisfied
-  --> $DIR/explicit-drop-bounds.rs:40:13
+  --> $DIR/explicit-drop-bounds.rs:40:18
    |
 LL |     fn drop(&mut self) {}
-   |             ^^^^^^^^^ the trait `Copy` is not implemented for `T`
+   |                  ^^^^ the trait `Copy` is not implemented for `T`
    |
 note: required by a bound in `DropMe`
   --> $DIR/explicit-drop-bounds.rs:7:18

tests/ui/mismatched_types/closure-arg-type-mismatch-issue-45727.stderr

@@ -10,7 +10,7 @@ LL |     let _ = (-10..=10).find(|x: i32| x.signum() == 0);
               found closure signature `fn(i32) -> _`
 note: required by a bound in `find`
   --> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL
-help: consider borrowing the argument
+help: consider adjusting the signature so it borrows its argument
    |
 LL |     let _ = (-10..=10).find(|x: &i32| x.signum() == 0);
    |                                 +
@@ -27,7 +27,7 @@ LL |     let _ = (-10..=10).find(|x: &&&i32| x.signum() == 0);
               found closure signature `for<'a, 'b, 'c> fn(&'a &'b &'c i32) -> _`
 note: required by a bound in `find`
   --> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL
-help: do not borrow the argument
+help: consider adjusting the signature so it does not borrow its argument
    |
 LL -     let _ = (-10..=10).find(|x: &&&i32| x.signum() == 0);
 LL +     let _ = (-10..=10).find(|x: &i32| x.signum() == 0);

tests/ui/mismatched_types/closure-arg-type-mismatch.stderr

@@ -10,7 +10,7 @@ LL |     a.iter().map(|_: (u32, u32)| 45);
               found closure signature `fn((u32, u32)) -> _`
 note: required by a bound in `map`
   --> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL
-help: consider borrowing the argument
+help: consider adjusting the signature so it borrows its argument
    |
 LL |     a.iter().map(|_: &(u32, u32)| 45);
    |                      +

tests/ui/mismatched_types/issue-36053-2.stderr

@@ -10,7 +10,7 @@ LL |     once::<&str>("str").fuse().filter(|a: &str| true).count();
               found closure signature `for<'a> fn(&'a str) -> _`
 note: required by a bound in `filter`
   --> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL
-help: consider borrowing the argument
+help: consider adjusting the signature so it borrows its argument
    |
 LL |     once::<&str>("str").fuse().filter(|a: &&str| true).count();
    |                                           +

tests/ui/mismatched_types/suggest-option-asderef-inference-var.stderr

@@ -13,7 +13,7 @@ LL |     let _has_inference_vars: Option<i32> = Some(0).map(deref_int);
               found function signature `for<'a> fn(&'a i32) -> _`
 note: required by a bound in `Option::<T>::map`
   --> $SRC_DIR/core/src/option.rs:LL:COL
-help: do not borrow the argument
+help: consider adjusting the signature so it does not borrow its argument
    |
 LL - fn deref_int(a: &i32) -> i32 {
 LL + fn deref_int(a: i32) -> i32 {

tests/ui/mismatched_types/suggest-option-asderef.fixed

@@ -17,7 +17,7 @@ fn generic<T>(_: T) -> Option<()> {
 }
 
 fn generic_ref<T>(_: T) -> Option<()> {
-    //~^ HELP do not borrow the argument
+    //~^ HELP consider adjusting the signature so it does not borrow its argument
     Some(())
 }
 

tests/ui/mismatched_types/suggest-option-asderef.rs

@@ -17,7 +17,7 @@ fn generic<T>(_: T) -> Option<()> {
 }
 
 fn generic_ref<T>(_: &T) -> Option<()> {
-    //~^ HELP do not borrow the argument
+    //~^ HELP consider adjusting the signature so it does not borrow its argument
     Some(())
 }
 

tests/ui/mismatched_types/suggest-option-asderef.stderr

@@ -73,7 +73,7 @@ LL |     let _ = produces_string().and_then(generic_ref);
               found function signature `for<'a> fn(&'a _) -> _`
 note: required by a bound in `Option::<T>::and_then`
   --> $SRC_DIR/core/src/option.rs:LL:COL
-help: do not borrow the argument
+help: consider adjusting the signature so it does not borrow its argument
    |
 LL - fn generic_ref<T>(_: &T) -> Option<()> {
 LL + fn generic_ref<T>(_: T) -> Option<()> {

tests/ui/specialization/min_specialization/issue-79224.stderr

@@ -11,10 +11,10 @@ LL | impl<B: ?Sized + std::clone::Clone> Display for Cow<'_, B> {
    |                +++++++++++++++++++
 
 error[E0277]: the trait bound `B: Clone` is not satisfied
-  --> $DIR/issue-79224.rs:20:12
+  --> $DIR/issue-79224.rs:20:13
    |
 LL |     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-   |            ^^^^^ the trait `Clone` is not implemented for `B`
+   |             ^^^^ the trait `Clone` is not implemented for `B`
    |
    = note: required for `B` to implement `ToOwned`
 help: consider further restricting this bound

tests/ui/suggestions/late-bound-in-borrow-closure-sugg.stderr

@@ -16,7 +16,7 @@ note: required by a bound in `Trader::<'a>::set_closure`
    |
 LL |     pub fn set_closure(&mut self, function: impl Fn(&mut Trader) + 'a) {
    |                                                  ^^^^^^^^^^^^^^^ required by this bound in `Trader::<'a>::set_closure`
-help: consider borrowing the argument
+help: consider adjusting the signature so it borrows its argument
    |
 LL |     let closure = |trader : &mut Trader| {
    |                             ++++

tests/ui/typeck/mismatched-map-under-self.rs

@@ -0,0 +1,17 @@
+pub trait Insertable {
+    type Values;
+
+    fn values(&self) -> Self::Values;
+}
+
+impl<T> Insertable for Option<T> {
+    type Values = ();
+
+    fn values(self) -> Self::Values {
+        //~^ ERROR method `values` has an incompatible type for trait
+        self.map(Insertable::values).unwrap_or_default()
+        //~^ ERROR type mismatch in function arguments
+    }
+}
+
+fn main() {}

tests/ui/typeck/mismatched-map-under-self.stderr

@@ -0,0 +1,37 @@
+error[E0053]: method `values` has an incompatible type for trait
+  --> $DIR/mismatched-map-under-self.rs:10:15
+   |
+LL |     fn values(self) -> Self::Values {
+   |               ^^^^
+   |               |
+   |               expected `&Option<T>`, found `Option<T>`
+   |               help: change the self-receiver type to match the trait: `&self`
+   |
+note: type in trait
+  --> $DIR/mismatched-map-under-self.rs:4:15
+   |
+LL |     fn values(&self) -> Self::Values;
+   |               ^^^^^
+   = note: expected signature `fn(&Option<T>)`
+              found signature `fn(Option<T>)`
+
+error[E0631]: type mismatch in function arguments
+  --> $DIR/mismatched-map-under-self.rs:12:18
+   |
+LL |     fn values(&self) -> Self::Values;
+   |     --------------------------------- found signature defined here
+...
+LL |         self.map(Insertable::values).unwrap_or_default()
+   |              --- ^^^^^^^^^^^^^^^^^^ expected due to this
+   |              |
+   |              required by a bound introduced by this call
+   |
+   = note: expected function signature `fn(T) -> _`
+              found function signature `for<'a> fn(&'a _) -> _`
+note: required by a bound in `Option::<T>::map`
+  --> $SRC_DIR/core/src/option.rs:LL:COL
+
+error: aborting due to 2 previous errors
+
+Some errors have detailed explanations: E0053, E0631.
+For more information about an error, try `rustc --explain E0053`.