Reduce verbosity of suggestion message and mention lifetime in label

src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs

@@ -1,6 +1,5 @@
 //! Error Reporting for static impl Traits.
 
-use crate::infer::error_reporting::msg_span_from_free_region;
 use crate::infer::error_reporting::nice_region_error::NiceRegionError;
 use crate::infer::lexical_region_resolve::RegionResolutionError;
 use rustc_errors::{Applicability, ErrorReported};
@@ -33,9 +32,17 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                     let sp = var_origin.span();
                     let return_sp = sub_origin.span();
                     let param_info = self.find_param_with_region(sup_r, sub_r)?;
+                    let (lifetime_name, lifetime) = if sup_r.has_name() {
+                        (sup_r.to_string(), format!("lifetime `{}`", sup_r))
+                    } else {
+                        ("'_".to_owned(), "the anonymous lifetime `'_`".to_string())
+                    };
                     let mut err =
                         self.tcx().sess.struct_span_err(sp, "cannot infer an appropriate lifetime");
-                    err.span_label(param_info.param_ty_span, "data with this lifetime...");
+                    err.span_label(
+                        param_info.param_ty_span,
+                        &format!("this data with {}...", lifetime),
+                    );
                     debug!("try_report_static_impl_trait: param_info={:?}", param_info);
 
                     // We try to make the output have fewer overlapping spans if possible.
@@ -60,10 +67,6 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                         );
                     }
 
-                    let (lifetime, _) = msg_span_from_free_region(self.tcx(), sup_r);
-
-                    let lifetime_name =
-                        if sup_r.has_name() { sup_r.to_string() } else { "'_".to_owned() };
                     // only apply this suggestion onto functions with
                     // explicit non-desugar'able return.
                     if fn_return.span.desugaring_kind().is_none() {
@@ -93,8 +96,11 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                                 {
                                     err.span_suggestion_verbose(
                                         span,
-                                        "consider changing the `impl Trait`'s explicit \
-                                         `'static` bound",
+                                        &format!(
+                                            "consider changing the `impl Trait`'s explicit \
+                                             `'static` bound to {}",
+                                            lifetime,
+                                        ),
                                         lifetime_name,
                                         Applicability::MaybeIncorrect,
                                     );
@@ -118,40 +124,41 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                                     );
                                 };
                             }
-                            TyKind::TraitObject(_, lt) => {
-                                match lt.name {
-                                    LifetimeName::ImplicitObjectLifetimeDefault => {
-                                        err.span_suggestion_verbose(
-                                            fn_return.span.shrink_to_hi(),
-                                            &format!(
-                                                "to permit non-static references in a trait object \
-                                                 value, you can add an explicit bound for {}",
-                                                lifetime,
-                                            ),
-                                            format!(" + {}", lifetime_name),
-                                            Applicability::MaybeIncorrect,
-                                        );
-                                    }
-                                    _ => {
-                                        err.span_suggestion_verbose(
-                                            lt.span,
+                            TyKind::TraitObject(_, lt) => match lt.name {
+                                LifetimeName::ImplicitObjectLifetimeDefault => {
+                                    err.span_suggestion_verbose(
+                                        fn_return.span.shrink_to_hi(),
+                                        &format!(
+                                            "to permit non-static references in a trait object \
+                                             value, you can add an explicit bound for {}",
+                                            lifetime,
+                                        ),
+                                        format!(" + {}", lifetime_name),
+                                        Applicability::MaybeIncorrect,
+                                    );
+                                }
+                                _ => {
+                                    err.span_suggestion_verbose(
+                                        lt.span,
+                                        &format!(
                                             "consider changing the trait object's explicit \
-                                             `'static` bound",
-                                            lifetime_name,
-                                            Applicability::MaybeIncorrect,
-                                        );
-                                        err.span_suggestion_verbose(
-                                            param_info.param_ty_span,
-                                            &format!(
-                                                "alternatively, set an explicit `'static` lifetime \
-                                                 in this parameter",
-                                            ),
-                                            param_info.param_ty.to_string(),
-                                            Applicability::MaybeIncorrect,
-                                        );
-                                    }
+                                             `'static` bound to {}",
+                                            lifetime,
+                                        ),
+                                        lifetime_name,
+                                        Applicability::MaybeIncorrect,
+                                    );
+                                    err.span_suggestion_verbose(
+                                        param_info.param_ty_span,
+                                        &format!(
+                                            "alternatively, set an explicit `'static` lifetime \
+                                             in this parameter",
+                                        ),
+                                        param_info.param_ty.to_string(),
+                                        Applicability::MaybeIncorrect,
+                                    );
                                 }
-                            }
+                            },
                             _ => {}
                         }
                     }

src/test/ui/async-await/issues/issue-62097.stderr

@@ -4,7 +4,7 @@ error: cannot infer an appropriate lifetime
 LL |     pub async fn run_dummy_fn(&self) {
    |                               ^^^^^
    |                               |
-   |                               data with this lifetime...
+   |                               this data with the anonymous lifetime `'_`...
    |                               ...is captured here...
 LL |         foo(|| self.bar()).await;
    |         --- ...and required to be `'static` by this

src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr

@@ -5,9 +5,9 @@ LL | fn elided(x: &i32) -> impl Copy { x }
    |              ----     ---------   ^ ...and is captured here
    |              |        |
    |              |        ...is required to be `'static` by this...
-   |              data with this lifetime...
+   |              this data with the anonymous lifetime `'_`...
    |
-help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for the anonymous lifetime #1 defined on the function body at 3:1
+help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for the anonymous lifetime `'_`
    |
 LL | fn elided(x: &i32) -> impl Copy + '_ { x }
    |                                 ^^^^
@@ -19,9 +19,9 @@ LL | fn explicit<'a>(x: &'a i32) -> impl Copy { x }
    |                    -------     ---------   ^ ...and is captured here
    |                    |           |
    |                    |           ...is required to be `'static` by this...
-   |                    data with this lifetime...
+   |                    this data with lifetime `'a`...
    |
-help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for the lifetime `'a` as defined on the function body at 6:13
+help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for lifetime `'a`
    |
 LL | fn explicit<'a>(x: &'a i32) -> impl Copy + 'a { x }
    |                                          ^^^^
@@ -33,9 +33,9 @@ LL | fn elided2(x: &i32) -> impl Copy + 'static { x }
    |               ----     -------------------   ^ ...and is captured here
    |               |        |
    |               |        ...is required to be `'static` by this...
-   |               data with this lifetime...
+   |               this data with the anonymous lifetime `'_`...
    |
-help: consider changing the `impl Trait`'s explicit `'static` bound
+help: consider changing the `impl Trait`'s explicit `'static` bound to the anonymous lifetime `'_`
    |
 LL | fn elided2(x: &i32) -> impl Copy + '_ { x }
    |                                    ^^
@@ -51,9 +51,9 @@ LL | fn explicit2<'a>(x: &'a i32) -> impl Copy + 'static { x }
    |                     -------     -------------------   ^ ...and is captured here
    |                     |           |
    |                     |           ...is required to be `'static` by this...
-   |                     data with this lifetime...
+   |                     this data with lifetime `'a`...
    |
-help: consider changing the `impl Trait`'s explicit `'static` bound
+help: consider changing the `impl Trait`'s explicit `'static` bound to lifetime `'a`
    |
 LL | fn explicit2<'a>(x: &'a i32) -> impl Copy + 'a { x }
    |                                             ^^
@@ -77,9 +77,9 @@ LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'static { x }
    |                      -------     --------------------------------   ^ ...and is captured here
    |                      |           |
    |                      |           ...is required to be `'static` by this...
-   |                      data with this lifetime...
+   |                      this data with lifetime `'a`...
    |
-help: consider changing the `impl Trait`'s explicit `'static` bound
+help: consider changing the `impl Trait`'s explicit `'static` bound to lifetime `'a`
    |
 LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'a { x }
    |                                                           ^^
@@ -113,9 +113,9 @@ LL | fn elided3(x: &i32) -> Box<dyn Debug> { Box::new(x) }
    |               |                         |        |
    |               |                         |        ...and is captured here
    |               |                         ...is required to be `'static` by this...
-   |               data with this lifetime...
+   |               this data with the anonymous lifetime `'_`...
    |
-help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime #1 defined on the function body at 18:1
+help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime `'_`
    |
 LL | fn elided3(x: &i32) -> Box<dyn Debug + '_> { Box::new(x) }
    |                                      ^^^^
@@ -128,9 +128,9 @@ LL | fn explicit3<'a>(x: &'a i32) -> Box<dyn Debug> { Box::new(x) }
    |                     |                            |        |
    |                     |                            |        ...and is captured here
    |                     |                            ...is required to be `'static` by this...
-   |                     data with this lifetime...
+   |                     this data with lifetime `'a`...
    |
-help: to permit non-static references in a trait object value, you can add an explicit bound for the lifetime `'a` as defined on the function body at 21:14
+help: to permit non-static references in a trait object value, you can add an explicit bound for lifetime `'a`
    |
 LL | fn explicit3<'a>(x: &'a i32) -> Box<dyn Debug + 'a> { Box::new(x) }
    |                                               ^^^^
@@ -142,9 +142,10 @@ LL | fn elided4(x: &i32) -> Box<dyn Debug + 'static> { Box::new(x) }
    |               ----                                ---------^-
    |               |                                   |        |
    |               |                                   |        ...and is captured here
-   |               data with this lifetime...          ...is required to be `'static` by this...
+   |               |                                   ...is required to be `'static` by this...
+   |               this data with the anonymous lifetime `'_`...
    |
-help: consider changing the trait object's explicit `'static` bound
+help: consider changing the trait object's explicit `'static` bound to the anonymous lifetime `'_`
    |
 LL | fn elided4(x: &i32) -> Box<dyn Debug + '_> { Box::new(x) }
    |                                        ^^
@@ -160,9 +161,10 @@ LL | fn explicit4<'a>(x: &'a i32) -> Box<dyn Debug + 'static> { Box::new(x) }
    |                     -------                                ---------^-
    |                     |                                      |        |
    |                     |                                      |        ...and is captured here
-   |                     data with this lifetime...             ...is required to be `'static` by this...
+   |                     |                                      ...is required to be `'static` by this...
+   |                     this data with lifetime `'a`...
    |
-help: consider changing the trait object's explicit `'static` bound
+help: consider changing the trait object's explicit `'static` bound to lifetime `'a`
    |
 LL | fn explicit4<'a>(x: &'a i32) -> Box<dyn Debug + 'a> { Box::new(x) }
    |                                                 ^^

src/test/ui/impl-trait/static-return-lifetime-infered.stderr

@@ -4,13 +4,13 @@ error: cannot infer an appropriate lifetime
 LL |     fn iter_values_anon(&self) -> impl Iterator<Item=u32> {
    |                         -----     ----------------------- ...is required to be `'static` by this...
    |                         |
-   |                         data with this lifetime...
+   |                         this data with the anonymous lifetime `'_`...
 LL |         self.x.iter().map(|a| a.0)
    |         ------ ^^^^
    |         |
    |         ...and is captured here
    |
-help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for the anonymous lifetime #1 defined on the method body at 6:5
+help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for the anonymous lifetime `'_`
    |
 LL |     fn iter_values_anon(&self) -> impl Iterator<Item=u32> + '_ {
    |                                                           ^^^^
@@ -21,13 +21,13 @@ error: cannot infer an appropriate lifetime
 LL |     fn iter_values<'a>(&'a self) -> impl Iterator<Item=u32> {
    |                        --------     ----------------------- ...is required to be `'static` by this...
    |                        |
-   |                        data with this lifetime...
+   |                        this data with lifetime `'a`...
 LL |         self.x.iter().map(|a| a.0)
    |         ------ ^^^^
    |         |
    |         ...and is captured here
    |
-help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for the lifetime `'a` as defined on the method body at 10:20
+help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for lifetime `'a`
    |
 LL |     fn iter_values<'a>(&'a self) -> impl Iterator<Item=u32> + 'a {
    |                                                             ^^^^

src/test/ui/issues/issue-16922.stderr

@@ -2,14 +2,14 @@ error: cannot infer an appropriate lifetime
   --> $DIR/issue-16922.rs:4:14
    |
 LL | fn foo<T: Any>(value: &T) -> Box<dyn Any> {
-   |                       -- data with this lifetime...
+   |                       -- this data with the anonymous lifetime `'_`...
 LL |     Box::new(value) as Box<dyn Any>
    |     ---------^^^^^-
    |     |        |
    |     |        ...and is captured here
    |     ...is required to be `'static` by this...
    |
-help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime #1 defined on the function body at 3:1
+help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime `'_`
    |
 LL | fn foo<T: Any>(value: &T) -> Box<dyn Any + '_> {
    |                                          ^^^^

src/test/ui/object-lifetime/object-lifetime-default-from-box-error.stderr

@@ -2,12 +2,12 @@ error: cannot infer an appropriate lifetime
   --> $DIR/object-lifetime-default-from-box-error.rs:18:5
    |
 LL | fn load(ss: &mut SomeStruct) -> Box<dyn SomeTrait> {
-   |             --------------- data with this lifetime...
+   |             --------------- this data with the anonymous lifetime `'_`...
 ...
 LL |     ss.r
    |     ^^^^ ...is captured and required to be `'static` here
    |
-help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime #2 defined on the function body at 14:1
+help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime `'_`
    |
 LL | fn load(ss: &mut SomeStruct) -> Box<dyn SomeTrait + '_> {
    |                                                   ^^^^

src/test/ui/regions/region-object-lifetime-in-coercion.stderr

@@ -2,14 +2,14 @@ error: cannot infer an appropriate lifetime
   --> $DIR/region-object-lifetime-in-coercion.rs:8:46
    |
 LL | fn a(v: &[u8]) -> Box<dyn Foo + 'static> {
-   |         ----- data with this lifetime...
+   |         ----- this data with the anonymous lifetime `'_`...
 LL |     let x: Box<dyn Foo + 'static> = Box::new(v);
    |                                     ---------^-
    |                                     |        |
    |                                     |        ...and is captured here
    |                                     ...is required to be `'static` by this...
    |
-help: consider changing the trait object's explicit `'static` bound
+help: consider changing the trait object's explicit `'static` bound to the anonymous lifetime `'_`
    |
 LL | fn a(v: &[u8]) -> Box<dyn Foo + '_> {
    |                                 ^^
@@ -22,14 +22,14 @@ error: cannot infer an appropriate lifetime
   --> $DIR/region-object-lifetime-in-coercion.rs:13:14
    |
 LL | fn b(v: &[u8]) -> Box<dyn Foo + 'static> {
-   |         ----- data with this lifetime...
+   |         ----- this data with the anonymous lifetime `'_`...
 LL |     Box::new(v)
    |     ---------^-
    |     |        |
    |     |        ...and is captured here
    |     ...is required to be `'static` by this...
    |
-help: consider changing the trait object's explicit `'static` bound
+help: consider changing the trait object's explicit `'static` bound to the anonymous lifetime `'_`
    |
 LL | fn b(v: &[u8]) -> Box<dyn Foo + '_> {
    |                                 ^^
@@ -42,15 +42,15 @@ error: cannot infer an appropriate lifetime
   --> $DIR/region-object-lifetime-in-coercion.rs:19:14
    |
 LL | fn c(v: &[u8]) -> Box<dyn Foo> {
-   |         ----- data with this lifetime...
+   |         ----- this data with the anonymous lifetime `'_`...
 ...
 LL |     Box::new(v)
    |     ---------^-
    |     |        |
    |     |        ...and is captured here
    |     ...is required to be `'static` by this...
    |
-help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime #1 defined on the function body at 16:1
+help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime `'_`
    |
 LL | fn c(v: &[u8]) -> Box<dyn Foo + '_> {
    |                               ^^^^

src/test/ui/regions/regions-close-object-into-object-2.stderr

@@ -2,14 +2,14 @@ error: cannot infer an appropriate lifetime
   --> $DIR/regions-close-object-into-object-2.rs:10:11
    |
 LL | fn g<'a, T: 'static>(v: Box<dyn A<T> + 'a>) -> Box<dyn X + 'static> {
-   |                         ------------------ data with this lifetime...
+   |                         ------------------ this data with lifetime `'a`...
 LL |     box B(&*v) as Box<dyn X>
    |     ------^^^---------------
    |     |     |
    |     |     ...and is captured here
    |     ...is required to be `'static` by this...
    |
-help: consider changing the trait object's explicit `'static` bound
+help: consider changing the trait object's explicit `'static` bound to lifetime `'a`
    |
 LL | fn g<'a, T: 'static>(v: Box<dyn A<T> + 'a>) -> Box<dyn X + 'a> {
    |                                                            ^^

src/test/ui/regions/regions-close-object-into-object-4.stderr

@@ -2,14 +2,14 @@ error: cannot infer an appropriate lifetime
   --> $DIR/regions-close-object-into-object-4.rs:10:11
    |
 LL | fn i<'a, T, U>(v: Box<dyn A<U>+'a>) -> Box<dyn X + 'static> {
-   |                   ---------------- data with this lifetime...
+   |                   ---------------- this data with lifetime `'a`...
 LL |     box B(&*v) as Box<dyn X>
    |     ------^^^---------------
    |     |     |
    |     |     ...and is captured here
    |     ...is required to be `'static` by this...
    |
-help: consider changing the trait object's explicit `'static` bound
+help: consider changing the trait object's explicit `'static` bound to lifetime `'a`
    |
 LL | fn i<'a, T, U>(v: Box<dyn A<U>+'a>) -> Box<dyn X + 'a> {
    |                                                    ^^

src/test/ui/regions/regions-proc-bound-capture.stderr

@@ -2,15 +2,15 @@ error: cannot infer an appropriate lifetime
   --> $DIR/regions-proc-bound-capture.rs:9:14
    |
 LL | fn static_proc(x: &isize) -> Box<dyn FnMut() -> (isize) + 'static> {
-   |                   ------ data with this lifetime...
+   |                   ------ this data with the anonymous lifetime `'_`...
 LL |     // This is illegal, because the region bound on `proc` is 'static.
 LL |     Box::new(move || { *x })
    |     ---------^^^^^^^^^^^^^^-
    |     |        |
    |     |        ...and is captured here
    |     ...is required to be `'static` by this...
    |
-help: consider changing the trait object's explicit `'static` bound
+help: consider changing the trait object's explicit `'static` bound to the anonymous lifetime `'_`
    |
 LL | fn static_proc(x: &isize) -> Box<dyn FnMut() -> (isize) + '_> {
    |                                                           ^^

src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait-async.stderr

@@ -4,7 +4,7 @@ error: cannot infer an appropriate lifetime
 LL |     async fn f(self: Pin<&Self>) -> impl Clone { self }
    |                ^^^^  ----------     ---------- ...and required to be `'static` by this
    |                |     |
-   |                |     data with this lifetime...
+   |                |     this data with the anonymous lifetime `'_`...
    |                ...is captured here...
 
 error: aborting due to previous error

src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait.stderr

@@ -5,9 +5,9 @@ LL |     fn f(self: Pin<&Self>) -> impl Clone { self }
    |                ----------     ----------   ^^^^ ...and is captured here
    |                |              |
    |                |              ...is required to be `'static` by this...
-   |                data with this lifetime...
+   |                this data with the anonymous lifetime `'_`...
    |
-help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for the anonymous lifetime #1 defined on the method body at 6:5
+help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for the anonymous lifetime `'_`
    |
 LL |     fn f(self: Pin<&Self>) -> impl Clone + '_ { self }
    |                                          ^^^^

src/test/ui/suggestions/lifetimes/missing-lifetimes-in-signature.stderr

@@ -12,14 +12,14 @@ error: cannot infer an appropriate lifetime
 LL |   fn foo<G, T>(g: G, dest: &mut T) -> impl FnOnce()
    |                            ------     ------------- ...is required to be `'static` by this...
    |                            |
-   |                            data with this lifetime...
+   |                            this data with the anonymous lifetime `'_`...
 ...
 LL | /     move || {
 LL | |         *dest = g.get();
 LL | |     }
    | |_____^ ...and is captured here
    |
-help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for the anonymous lifetime #1 defined on the function body at 15:1
+help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for the anonymous lifetime `'_`
    |
 LL | fn foo<G, T>(g: G, dest: &mut T) -> impl FnOnce() + '_
    |                                                   ^^^^

src/test/ui/underscore-lifetime/dyn-trait-underscore.stderr

@@ -2,12 +2,12 @@ error: cannot infer an appropriate lifetime
   --> $DIR/dyn-trait-underscore.rs:8:20
    |
 LL | fn a<T>(items: &[T]) -> Box<dyn Iterator<Item=&T>> {
-   |                ---- data with this lifetime...
+   |                ---- this data with the anonymous lifetime `'_`...
 LL |     //                      ^^^^^^^^^^^^^^^^^^^^^ bound *here* defaults to `'static`
 LL |     Box::new(items.iter())
    |     ---------------^^^^--- ...is captured and required to be `'static` here
    |
-help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime #1 defined on the function body at 6:1
+help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime `'_`
    |
 LL | fn a<T>(items: &[T]) -> Box<dyn Iterator<Item=&T> + '_> {
    |                                                   ^^^^