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Tweak wording and spans of 'static dyn Trait/impl Trait require…
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@estebank
estebank committed May 30, 2020
1 parent 6dcd744 commit 83f6f22
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Showing 11 changed files with 91 additions and 156 deletions.
47 changes: 26 additions & 21 deletions src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -27,39 +27,44 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
let return_sp = sub_origin.span();
let mut err =
self.tcx().sess.struct_span_err(sp, "cannot infer an appropriate lifetime");
if sp == sup_origin.span() && return_sp == sp {
// Example: `ui/object-lifetime/object-lifetime-default-from-box-error.rs`
err.span_label(
sup_origin.span(),
"this needs to be `'static` but the borrow...",
);
} else {
err.span_label(return_sp, "this is `'static`...");
// We try to make the output have fewer overlapping spans if possible.
if sp == sup_origin.span() || !return_sp.overlaps(sup_origin.span()) {
// When `sp == sup_origin` we already have overlapping spans in the
// main diagnostic output, so we don't split this into its own note.
err.span_label(sup_origin.span(), "...but this borrow...");
let param_info = self.find_param_with_region(sup_r, sub_r)?;
err.span_label(param_info.param_ty_span, "data with this lifetime...");

// We try to make the output have fewer overlapping spans if possible.
if (sp == sup_origin.span() || !return_sp.overlaps(sup_origin.span()))
&& sup_origin.span() != return_sp
{
// FIXME: account for `async fn` like in `async-await/issues/issue-62097.rs`

// Customize the spans and labels depending on their relative order so
// that split sentences flow correctly.
if sup_origin.span().shrink_to_hi() <= return_sp.shrink_to_lo() {
err.span_label(sup_origin.span(), "...is captured here...");
err.span_label(return_sp, "...and required to be `'static` by this");
} else {
err.span_note(sup_origin.span(), "...but this borrow...");
err.span_label(return_sp, "...is required to be `'static` by this...");
err.span_label(sup_origin.span(), "...and is captured here");
}
} else {
err.span_label(
return_sp,
"...is captured and required to be `'static` here",
);
}

let (lifetime, lt_sp_opt) = msg_span_from_free_region(self.tcx(), sup_r);
if let Some(lifetime_sp) = lt_sp_opt {
err.span_note(lifetime_sp, &format!("...can't outlive {}", lifetime));
}
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() {
let msg = format!(
"you can add a bound to the returned `{} Trait` to make it last less \
than `'static` and match {}",
"to permit non-static references in {} `{} Trait` value, you can add \
an explicit bound for {}",
if is_dyn { "a" } else { "an" },
if is_dyn { "dyn" } else { "impl" },
lifetime
lifetime,
);
// FIXME: account for the need of parens in `&(dyn Trait + '_)`
err.span_suggestion_verbose(
Expand Down
13 changes: 5 additions & 8 deletions src/test/ui/async-await/issues/issue-62097.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -2,15 +2,12 @@ error: cannot infer an appropriate lifetime
--> $DIR/issue-62097.rs:12:31
|
LL | pub async fn run_dummy_fn(&self) {
| ^^^^^ ...but this borrow...
| ^^^^^
| |
| data with this lifetime...
| ...is captured here...
LL | foo(|| self.bar()).await;
| --- this is `'static`...
|
note: ...can't outlive the lifetime `'_` as defined on the method body at 12:31
--> $DIR/issue-62097.rs:12:31
|
LL | pub async fn run_dummy_fn(&self) {
| ^
| --- ...and required to be `'static` by this

error: aborting due to previous error

42 changes: 15 additions & 27 deletions src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -2,16 +2,12 @@ error: cannot infer an appropriate lifetime
--> $DIR/must_outlive_least_region_or_bound.rs:3:35
|
LL | fn elided(x: &i32) -> impl Copy { x }
| --------- ^ ...but this borrow...
| |
| this is `'static`...
| ---- --------- ^ ...and is captured here
| | |
| | ...is required to be `'static` by this...
| data with this lifetime...
|
note: ...can't outlive the anonymous lifetime #1 defined on the function body at 3:1
--> $DIR/must_outlive_least_region_or_bound.rs:3:1
|
LL | fn elided(x: &i32) -> impl Copy { x }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
help: you can add a bound to the returned `impl Trait` to make it last less than `'static` and match 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 #1 defined on the function body at 3:1
|
LL | fn elided(x: &i32) -> impl Copy + '_ { x }
| ^^^^
Expand All @@ -20,16 +16,12 @@ error: cannot infer an appropriate lifetime
--> $DIR/must_outlive_least_region_or_bound.rs:6:44
|
LL | fn explicit<'a>(x: &'a i32) -> impl Copy { x }
| --------- ^ ...but this borrow...
| |
| this is `'static`...
|
note: ...can't outlive the lifetime `'a` as defined on the function body at 6:13
--> $DIR/must_outlive_least_region_or_bound.rs:6:13
| ------- --------- ^ ...and is captured here
| | |
| | ...is required to be `'static` by this...
| data with this lifetime...
|
LL | fn explicit<'a>(x: &'a i32) -> impl Copy { x }
| ^^
help: you can add a bound to the returned `impl Trait` to make it last less than `'static` and match 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 the lifetime `'a` as defined on the function body at 6:13
|
LL | fn explicit<'a>(x: &'a i32) -> impl Copy + 'a { x }
| ^^^^
Expand All @@ -38,16 +30,12 @@ error: cannot infer an appropriate lifetime
--> $DIR/must_outlive_least_region_or_bound.rs:12:69
|
LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'static { x }
| -------------------------------- ^ ...but this borrow...
| |
| this is `'static`...
|
note: ...can't outlive the lifetime `'a` as defined on the function body at 12:15
--> $DIR/must_outlive_least_region_or_bound.rs:12:15
| ------- -------------------------------- ^ ...and is captured here
| | |
| | ...is required to be `'static` by this...
| data with this lifetime...
|
LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'static { x }
| ^^
help: you can add a bound to the returned `impl Trait` to make it last less than `'static` and match the lifetime `'a` as defined on the function body at 12:15
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 12:15
|
LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'static + 'a { x }
| ^^^^
Expand Down
28 changes: 10 additions & 18 deletions src/test/ui/impl-trait/static-return-lifetime-infered.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -2,20 +2,15 @@ error: cannot infer an appropriate lifetime
--> $DIR/static-return-lifetime-infered.rs:7:16
|
LL | fn iter_values_anon(&self) -> impl Iterator<Item=u32> {
| ----------------------- this is `'static`...
| ----- ----------------------- ...is required to be `'static` by this...
| |
| data with this lifetime...
LL | self.x.iter().map(|a| a.0)
| ------ ^^^^
| |
| ...but this borrow...
| ...and is captured here
|
note: ...can't outlive the anonymous lifetime #1 defined on the method body at 6:5
--> $DIR/static-return-lifetime-infered.rs:6:5
|
LL | / fn iter_values_anon(&self) -> impl Iterator<Item=u32> {
LL | | self.x.iter().map(|a| a.0)
LL | | }
| |_____^
help: you can add a bound to the returned `impl Trait` to make it last less than `'static` and match 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 #1 defined on the method body at 6:5
|
LL | fn iter_values_anon(&self) -> impl Iterator<Item=u32> + '_ {
| ^^^^
Expand All @@ -24,18 +19,15 @@ error: cannot infer an appropriate lifetime
--> $DIR/static-return-lifetime-infered.rs:11:16
|
LL | fn iter_values<'a>(&'a self) -> impl Iterator<Item=u32> {
| ----------------------- this is `'static`...
| -------- ----------------------- ...is required to be `'static` by this...
| |
| data with this lifetime...
LL | self.x.iter().map(|a| a.0)
| ------ ^^^^
| |
| ...but this borrow...
|
note: ...can't outlive the lifetime `'a` as defined on the method body at 10:20
--> $DIR/static-return-lifetime-infered.rs:10:20
| ...and is captured here
|
LL | fn iter_values<'a>(&'a self) -> impl Iterator<Item=u32> {
| ^^
help: you can add a bound to the returned `impl Trait` to make it last less than `'static` and match 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 the lifetime `'a` as defined on the method body at 10:20
|
LL | fn iter_values<'a>(&'a self) -> impl Iterator<Item=u32> + 'a {
| ^^^^
Expand Down
16 changes: 5 additions & 11 deletions src/test/ui/issues/issue-16922.stderr
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Original file line number Diff line number Diff line change
@@ -1,21 +1,15 @@
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...
LL | Box::new(value) as Box<dyn Any>
| ---------^^^^^-
| | |
| | ...but this borrow...
| this is `'static`...
| | ...and is captured here
| ...is required to be `'static` by this...
|
note: ...can't outlive the anonymous lifetime #1 defined on the function body at 3:1
--> $DIR/issue-16922.rs:3:1
|
LL | / fn foo<T: Any>(value: &T) -> Box<dyn Any> {
LL | | Box::new(value) as Box<dyn Any>
LL | |
LL | | }
| |_^
help: you can add a bound to the returned `dyn Trait` to make it last less than `'static` and match the anonymous lifetime #1 defined on the function body at 3:1
help: to permit non-static references in a `dyn Trait` value, you can add an explicit bound for the anonymous lifetime #1 defined on the function body at 3:1
|
LL | fn foo<T: Any>(value: &T) -> Box<dyn Any + '_> {
| ^^^^
Expand Down
17 changes: 5 additions & 12 deletions src/test/ui/object-lifetime/object-lifetime-default-from-box-error.stderr
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Original file line number Diff line number Diff line change
@@ -1,20 +1,13 @@
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...
...
LL | ss.r
| ^^^^ this needs to be `'static` but the borrow...
|
note: ...can't outlive the anonymous lifetime #2 defined on the function body at 14:1
--> $DIR/object-lifetime-default-from-box-error.rs:14:1
| ^^^^ ...is captured and required to be `'static` here
|
LL | / fn load(ss: &mut SomeStruct) -> Box<dyn SomeTrait> {
LL | | // `Box<SomeTrait>` defaults to a `'static` bound, so this return
LL | | // is illegal.
LL | |
LL | | ss.r
LL | | }
| |_^
help: you can add a bound to the returned `dyn Trait` to make it last less than `'static` and match the anonymous lifetime #2 defined on the function body at 14:1
help: to permit non-static references in a `dyn Trait` value, you can add an explicit bound for the anonymous lifetime #2 defined on the function body at 14:1
|
LL | fn load(ss: &mut SomeStruct) -> Box<dyn SomeTrait + '_> {
| ^^^^
Expand Down
18 changes: 6 additions & 12 deletions src/test/ui/regions/region-object-lifetime-in-coercion.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -17,22 +17,16 @@ LL | Box::new(v)
error: cannot infer an appropriate lifetime
--> $DIR/region-object-lifetime-in-coercion.rs:20:14
|
LL | fn c(v: &[u8]) -> Box<dyn Foo> {
| ----- data with this lifetime...
...
LL | Box::new(v)
| ---------^-
| | |
| | ...but this borrow...
| this is `'static`...
| | ...and is captured here
| ...is required to be `'static` by this...
|
note: ...can't outlive the anonymous lifetime #1 defined on the function body at 17:1
--> $DIR/region-object-lifetime-in-coercion.rs:17:1
|
LL | / fn c(v: &[u8]) -> Box<dyn Foo> {
LL | | // same as previous case due to RFC 599
LL | |
LL | | Box::new(v)
LL | | }
| |_^
help: you can add a bound to the returned `dyn Trait` to make it last less than `'static` and match the anonymous lifetime #1 defined on the function body at 17:1
help: to permit non-static references in a `dyn Trait` value, you can add an explicit bound for the anonymous lifetime #1 defined on the function body at 17:1
|
LL | fn c(v: &[u8]) -> Box<dyn Foo + '_> {
| ^^^^
Expand Down
13 changes: 4 additions & 9 deletions src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait-async.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -2,15 +2,10 @@ error: cannot infer an appropriate lifetime
--> $DIR/arbitrary_self_types_pin_lifetime_impl_trait-async.rs:8:16
|
LL | async fn f(self: Pin<&Self>) -> impl Clone { self }
| ^^^^ ---------- this is `'static`...
| |
| ...but this borrow...
|
note: ...can't outlive the lifetime `'_` as defined on the method body at 8:26
--> $DIR/arbitrary_self_types_pin_lifetime_impl_trait-async.rs:8:26
|
LL | async fn f(self: Pin<&Self>) -> impl Clone { self }
| ^
| ^^^^ ---------- ---------- ...and required to be `'static` by this
| | |
| | data with this lifetime...
| ...is captured here...

error: aborting due to previous error

14 changes: 5 additions & 9 deletions src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait.stderr
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2,16 +2,12 @@ error: cannot infer an appropriate lifetime
--> $DIR/arbitrary_self_types_pin_lifetime_impl_trait.rs:6:44
|
LL | fn f(self: Pin<&Self>) -> impl Clone { self }
| ---------- ^^^^ ...but this borrow...
| |
| this is `'static`...
| ---------- ---------- ^^^^ ...and is captured here
| | |
| | ...is required to be `'static` by this...
| data with this lifetime...
|
note: ...can't outlive the anonymous lifetime #1 defined on the method body at 6:5
--> $DIR/arbitrary_self_types_pin_lifetime_impl_trait.rs:6:5
|
LL | fn f(self: Pin<&Self>) -> impl Clone { self }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
help: you can add a bound to the returned `impl Trait` to make it last less than `'static` and match 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 #1 defined on the method body at 6:5
|
LL | fn f(self: Pin<&Self>) -> impl Clone + '_ { self }
| ^^^^
Expand Down
19 changes: 5 additions & 14 deletions src/test/ui/suggestions/lifetimes/missing-lifetimes-in-signature.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -10,25 +10,16 @@ error: cannot infer an appropriate lifetime
--> $DIR/missing-lifetimes-in-signature.rs:19:5
|
LL | fn foo<G, T>(g: G, dest: &mut T) -> impl FnOnce()
| ------------- this is `'static`...
| ------ ------------- ...is required to be `'static` by this...
| |
| data with this lifetime...
...
LL | / move || {
LL | | *dest = g.get();
LL | | }
| |_____^ ...but this borrow...
| |_____^ ...and is captured here
|
note: ...can't outlive the anonymous lifetime #1 defined on the function body at 15:1
--> $DIR/missing-lifetimes-in-signature.rs:15:1
|
LL | / fn foo<G, T>(g: G, dest: &mut T) -> impl FnOnce()
LL | | where
LL | | G: Get<T>
LL | | {
... |
LL | | }
LL | | }
| |_^
help: you can add a bound to the returned `impl Trait` to make it last less than `'static` and match 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 #1 defined on the function body at 15:1
|
LL | fn foo<G, T>(g: G, dest: &mut T) -> impl FnOnce() + '_
| ^^^^
Expand Down
20 changes: 5 additions & 15 deletions src/test/ui/underscore-lifetime/dyn-trait-underscore.stderr
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Original file line number Diff line number Diff line change
@@ -1,23 +1,13 @@
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...
LL | // ^^^^^^^^^^^^^^^^^^^^^ bound *here* defaults to `'static`
LL | Box::new(items.iter())
| ---------------^^^^--- this is `'static`...
| ---------------^^^^--- ...is captured and required to be `'static` here
|
note: ...but this borrow...
--> $DIR/dyn-trait-underscore.rs:8:14
|
LL | Box::new(items.iter())
| ^^^^^
note: ...can't outlive the anonymous lifetime #1 defined on the function body at 6:1
--> $DIR/dyn-trait-underscore.rs:6:1
|
LL | / fn a<T>(items: &[T]) -> Box<dyn Iterator<Item=&T>> {
LL | | // ^^^^^^^^^^^^^^^^^^^^^ bound *here* defaults to `'static`
LL | | Box::new(items.iter())
LL | | }
| |_^
help: you can add a bound to the returned `dyn Trait` to make it last less than `'static` and match the anonymous lifetime #1 defined on the function body at 6:1
help: to permit non-static references in a `dyn Trait` value, you can add an explicit bound for the anonymous lifetime #1 defined on the function body at 6:1
|
LL | fn a<T>(items: &[T]) -> Box<dyn Iterator<Item=&T> + '_> {
| ^^^^
Expand Down

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