Tweak wording of "implemented trait isn't imported" suggestion

Author: estebank

compiler/rustc_hir_typeck/src/method/suggest.rs

@@ -275,7 +275,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     .span_if_local(def_id)
                     .unwrap_or_else(|| self.tcx.def_span(def_id));
                 err.span_label(sp, format!("private {kind} defined here"));
-                self.suggest_valid_traits(&mut err, out_of_scope_traits, true);
+                self.suggest_valid_traits(&mut err, item_name, out_of_scope_traits, true);
                 err.emit();
             }
 
@@ -2890,6 +2890,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     fn suggest_valid_traits(
         &self,
         err: &mut DiagnosticBuilder<'_>,
+        item_name: Ident,
         valid_out_of_scope_traits: Vec<DefId>,
         explain: bool,
     ) -> bool {
@@ -2908,9 +2909,16 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 err.help("items from traits can only be used if the trait is in scope");
             }
             let msg = format!(
-                "the following {traits_are} implemented but not in scope; \
-                 perhaps add a `use` for {one_of_them}:",
-                traits_are = if candidates.len() == 1 { "trait is" } else { "traits are" },
+                "{this_trait_is} implemented but not in scope; perhaps you want to import \
+                 {one_of_them}",
+                this_trait_is = if candidates.len() == 1 {
+                    format!(
+                        "trait `{}` which provides `{item_name}` is",
+                        self.tcx.item_name(candidates[0]),
+                    )
+                } else {
+                    format!("the following traits which provide `{item_name}` are")
+                },
                 one_of_them = if candidates.len() == 1 { "it" } else { "one of them" },
             );
 
@@ -3118,7 +3126,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 }
             }
         }
-        if self.suggest_valid_traits(err, valid_out_of_scope_traits, true) {
+        if self.suggest_valid_traits(err, item_name, valid_out_of_scope_traits, true) {
             return;
         }
 
@@ -3404,7 +3412,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 [] => {}
                 [trait_info] if trait_info.def_id.is_local() => {
                     if impls_trait(trait_info.def_id) {
-                        self.suggest_valid_traits(err, vec![trait_info.def_id], false);
+                        self.suggest_valid_traits(err, item_name, vec![trait_info.def_id], false);
                     } else {
                         err.subdiagnostic(
                             self.dcx(),
@@ -3431,7 +3439,12 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     ));
                     for (i, trait_info) in trait_infos.iter().enumerate() {
                         if impls_trait(trait_info.def_id) {
-                            self.suggest_valid_traits(err, vec![trait_info.def_id], false);
+                            self.suggest_valid_traits(
+                                err,
+                                item_name,
+                                vec![trait_info.def_id],
+                                false,
+                            );
                         }
                         msg.push_str(&format!(
                             "\ncandidate #{}: `{}`",

tests/ui/async-await/in-trait/dont-project-to-specializable-projection.stderr

@@ -30,7 +30,7 @@ LL |         match fut.as_mut().poll(ctx) {
    = note: the method is available for `Pin<&mut impl Future<Output = ()>>` here
    |
    = help: items from traits can only be used if the trait is in scope
-help: the following trait is implemented but not in scope; perhaps add a `use` for it:
+help: trait `Future` which provides `poll` is implemented but not in scope; perhaps you want to import it
    |
 LL + use std::future::Future;
    |

tests/ui/coherence/coherence_inherent.stderr

@@ -5,7 +5,7 @@ LL |         s.the_fn();
    |           ^^^^^^ method not found in `&TheStruct`
    |
    = help: items from traits can only be used if the trait is in scope
-help: the following trait is implemented but not in scope; perhaps add a `use` for it:
+help: trait `TheTrait` which provides `the_fn` is implemented but not in scope; perhaps you want to import it
    |
 LL +     use Lib::TheTrait;
    |

tests/ui/coherence/coherence_inherent_cc.stderr

@@ -5,7 +5,7 @@ LL |         s.the_fn();
    |           ^^^^^^ method not found in `&TheStruct`
    |
    = help: items from traits can only be used if the trait is in scope
-help: the following trait is implemented but not in scope; perhaps add a `use` for it:
+help: trait `TheTrait` which provides `the_fn` is implemented but not in scope; perhaps you want to import it
    |
 LL +     use coherence_inherent_cc_lib::TheTrait;
    |

tests/ui/hygiene/no_implicit_prelude.stderr

@@ -26,7 +26,7 @@ LL |         ().clone()
 help: there is a method `clone_from` with a similar name, but with different arguments
   --> $SRC_DIR/core/src/clone.rs:LL:COL
    = note: this error originates in the macro `::bar::m` (in Nightly builds, run with -Z macro-backtrace for more info)
-help: the following trait is implemented but not in scope; perhaps add a `use` for it:
+help: trait `Clone` which provides `clone` is implemented but not in scope; perhaps you want to import it
    |
 LL +     use std::clone::Clone;
    |

tests/ui/hygiene/trait_items.stderr

@@ -12,7 +12,7 @@ LL |     pub macro m() { ().f() }
    |
    = help: items from traits can only be used if the trait is in scope
    = note: this error originates in the macro `::baz::m` (in Nightly builds, run with -Z macro-backtrace for more info)
-help: the following trait is implemented but not in scope; perhaps add a `use` for it:
+help: trait `T` which provides `f` is implemented but not in scope; perhaps you want to import it
    |
 LL +     use foo::T;
    |

tests/ui/impl-trait/no-method-suggested-traits.stderr

@@ -5,7 +5,7 @@ LL |     1u32.method();
    |          ^^^^^^
    |
    = help: items from traits can only be used if the trait is in scope
-help: the following traits are implemented but not in scope; perhaps add a `use` for one of them:
+help: the following traits which provide `method` are implemented but not in scope; perhaps you want to import one of them
    |
 LL + use foo::Bar;
    |
@@ -27,7 +27,7 @@ LL |     std::rc::Rc::new(&mut Box::new(&1u32)).method();
    |                                            ^^^^^^
    |
    = help: items from traits can only be used if the trait is in scope
-help: the following traits are implemented but not in scope; perhaps add a `use` for one of them:
+help: the following traits which provide `method` are implemented but not in scope; perhaps you want to import one of them
    |
 LL + use foo::Bar;
    |
@@ -52,7 +52,7 @@ LL |     'a'.method();
    |         ^^^^^^
    |
    = help: items from traits can only be used if the trait is in scope
-help: the following trait is implemented but not in scope; perhaps add a `use` for it:
+help: trait `Bar` which provides `method` is implemented but not in scope; perhaps you want to import it
    |
 LL + use foo::Bar;
    |
@@ -68,7 +68,7 @@ LL |     std::rc::Rc::new(&mut Box::new(&'a')).method();
    |                                           ^^^^^^
    |
    = help: items from traits can only be used if the trait is in scope
-help: the following trait is implemented but not in scope; perhaps add a `use` for it:
+help: trait `Bar` which provides `method` is implemented but not in scope; perhaps you want to import it
    |
 LL + use foo::Bar;
    |
@@ -89,7 +89,7 @@ LL |         fn method(&self) {}
    |            ------ the method is available for `i32` here
    |
    = help: items from traits can only be used if the trait is in scope
-help: the following trait is implemented but not in scope; perhaps add a `use` for it:
+help: trait `PubPub` which provides `method` is implemented but not in scope; perhaps you want to import it
    |
 LL + use no_method_suggested_traits::foo::PubPub;
    |
@@ -105,7 +105,7 @@ LL |     std::rc::Rc::new(&mut Box::new(&1i32)).method();
    |                                            ^^^^^^
    |
    = help: items from traits can only be used if the trait is in scope
-help: the following trait is implemented but not in scope; perhaps add a `use` for it:
+help: trait `PubPub` which provides `method` is implemented but not in scope; perhaps you want to import it
    |
 LL + use no_method_suggested_traits::foo::PubPub;
    |

tests/ui/imports/overlapping_pub_trait.rs

@@ -4,7 +4,7 @@
  * This crate declares two public paths, `m::Tr` and `prelude::_`. Make sure we prefer the former.
  */
 extern crate overlapping_pub_trait_source;
-//~^ HELP the following trait is implemented but not in scope; perhaps add a `use` for it:
+//~^ HELP trait `Tr` which provides `method` is implemented but not in scope; perhaps you want to import it
 //~| SUGGESTION overlapping_pub_trait_source::m::Tr
 
 fn main() {

tests/ui/imports/overlapping_pub_trait.stderr

@@ -10,7 +10,7 @@ LL |     pub trait Tr { fn method(&self); }
    |                       ------ the method is available for `S` here
    |
    = help: items from traits can only be used if the trait is in scope
-help: the following trait is implemented but not in scope; perhaps add a `use` for it:
+help: trait `Tr` which provides `method` is implemented but not in scope; perhaps you want to import it
    |
 LL + use overlapping_pub_trait_source::m::Tr;
    |

tests/ui/imports/unnamed_pub_trait.rs

@@ -5,7 +5,7 @@
  * importing it by name, and instead we suggest importing it by glob.
  */
 extern crate unnamed_pub_trait_source;
-//~^ HELP the following trait is implemented but not in scope; perhaps add a `use` for it:
+//~^ HELP trait `Tr` which provides `method` is implemented but not in scope; perhaps you want to import it
 //~| SUGGESTION unnamed_pub_trait_source::prelude::*; // trait Tr
 
 fn main() {