user0/rust
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Rollup merge of #72804 - estebank:opaque-missing-lts-in-fn-2, r=nikomatsakis

Browse source 
Further tweak lifetime errors involving `dyn Trait` and `impl Trait` in return position

* Suggest substituting `'static` lifetime in impl/dyn `Trait + 'static` instead of `Trait + 'static + '_`
* When `'static` is explicit, also suggest constraining argument with it
* Reduce verbosity of suggestion message and mention lifetime in label
* Tweak output for overlapping required/captured spans
* Give these errors an error code

Follow up to #72543.

r? @nikomatsakis
This commit is contained in:
Manish Goregaokar 2020-06-18 15:20:43 -07:00 • committed by GitHub
commit 40fd2bdcfe
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
25 changed files with 617 additions and 211 deletions
Download patch file Download diff file Expand all files Collapse all files

38
src/test/ui/impl-trait/must_outlive_least_region_or_bound.nll.stderr
View file

@ -26,7 +26,34 @@ LL | fn explicit<'a>(x: &'a i32) -> impl Copy + 'a { x }
| ^^^^^^^^^^^^^^
error: lifetime may not live long enough
--> $DIR/must_outlive_least_region_or_bound.rs:12:69
--> $DIR/must_outlive_least_region_or_bound.rs:9:46
|
LL | fn elided2(x: &i32) -> impl Copy + 'static { x }
| - ^ returning this value requires that `'1` must outlive `'static`
| |
| let's call the lifetime of this reference `'1`
|
= help: consider replacing `'1` with `'static`
error: lifetime may not live long enough
--> $DIR/must_outlive_least_region_or_bound.rs:12:55
|
LL | fn explicit2<'a>(x: &'a i32) -> impl Copy + 'static { x }
| -- lifetime `'a` defined here ^ returning this value requires that `'a` must outlive `'static`
|
= help: consider replacing `'a` with `'static`
= help: consider replacing `'a` with `'static`
error[E0621]: explicit lifetime required in the type of `x`
--> $DIR/must_outlive_least_region_or_bound.rs:15:41
|
LL | fn foo<'a>(x: &i32) -> impl Copy + 'a { x }
| ---- ^ lifetime `'a` required
| |
| help: add explicit lifetime `'a` to the type of `x`: `&'a i32`
error: lifetime may not live long enough
--> $DIR/must_outlive_least_region_or_bound.rs:33:69
|
LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'static { x }
| -- lifetime `'a` defined here ^ returning this value requires that `'a` must outlive `'static`
@ -35,7 +62,7 @@ LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'static { x }
= help: consider replacing `'a` with `'static`
error: lifetime may not live long enough
--> $DIR/must_outlive_least_region_or_bound.rs:17:61
--> $DIR/must_outlive_least_region_or_bound.rs:38:61
|
LL | fn move_lifetime_into_fn<'a, 'b>(x: &'a u32, y: &'b u32) -> impl Fn(&'a u32) {
| -- -- lifetime `'b` defined here ^^^^^^^^^^^^^^^^ opaque type requires that `'b` must outlive `'a`
@ -45,13 +72,14 @@ LL | fn move_lifetime_into_fn<'a, 'b>(x: &'a u32, y: &'b u32) -> impl Fn(&'a u32
= help: consider adding the following bound: `'b: 'a`
error[E0310]: the parameter type `T` may not live long enough
--> $DIR/must_outlive_least_region_or_bound.rs:22:51
--> $DIR/must_outlive_least_region_or_bound.rs:43:51
|
LL | fn ty_param_wont_outlive_static<T:Debug>(x: T) -> impl Debug + 'static {
| ^^^^^^^^^^^^^^^^^^^^
|
= help: consider adding an explicit lifetime bound `T: 'static`...
error: aborting due to 5 previous errors
error: aborting due to 8 previous errors
For more information about this error, try `rustc --explain E0310`.
Some errors have detailed explanations: E0310, E0621.
For more information about an error, try `rustc --explain E0310`.

21
src/test/ui/impl-trait/must_outlive_least_region_or_bound.rs
View file

@ -6,6 +6,27 @@ fn elided(x: &i32) -> impl Copy { x }
fn explicit<'a>(x: &'a i32) -> impl Copy { x }
//~^ ERROR cannot infer an appropriate lifetime
fn elided2(x: &i32) -> impl Copy + 'static { x }
//~^ ERROR cannot infer an appropriate lifetime
fn explicit2<'a>(x: &'a i32) -> impl Copy + 'static { x }
//~^ ERROR cannot infer an appropriate lifetime
fn foo<'a>(x: &i32) -> impl Copy + 'a { x }
//~^ ERROR explicit lifetime required in the type of `x`
fn elided3(x: &i32) -> Box<dyn Debug> { Box::new(x) }
//~^ ERROR cannot infer an appropriate lifetime
fn explicit3<'a>(x: &'a i32) -> Box<dyn Debug> { Box::new(x) }
//~^ ERROR cannot infer an appropriate lifetime
fn elided4(x: &i32) -> Box<dyn Debug + 'static> { Box::new(x) }
//~^ ERROR cannot infer an appropriate lifetime
fn explicit4<'a>(x: &'a i32) -> Box<dyn Debug + 'static> { Box::new(x) }
//~^ ERROR cannot infer an appropriate lifetime
trait LifetimeTrait<'a> {}
impl<'a> LifetimeTrait<'a> for &'a i32 {}

174
src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
View file

@ -1,47 +1,113 @@
error: cannot infer an appropriate lifetime
error[E0759]: cannot infer an appropriate lifetime
--> $DIR/must_outlive_least_region_or_bound.rs:3:35
|
LL | fn elided(x: &i32) -> impl Copy { x }
| ---- --------- ^ ...and is captured here
| | |
| | ...is required to be `'static` by this...
| data with this lifetime...
| ---- ^ ...is captured here...
| |
| this data with an 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
note: ...and is required to live as long as `'static` here
--> $DIR/must_outlive_least_region_or_bound.rs:3:23
|
LL | fn elided(x: &i32) -> impl Copy { x }
| ^^^^^^^^^
help: to declare that the `impl Trait` captures data from argument `x`, you can add an explicit `'_` lifetime bound
|
LL | fn elided(x: &i32) -> impl Copy + '_ { x }
| ^^^^
error: cannot infer an appropriate lifetime
error[E0759]: 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 }
| ------- --------- ^ ...and is captured here
| | |
| | ...is required to be `'static` by this...
| data with this lifetime...
| ------- ^ ...is captured here...
| |
| 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
note: ...and is required to live as long as `'static` here
--> $DIR/must_outlive_least_region_or_bound.rs:6:32
|
LL | fn explicit<'a>(x: &'a i32) -> impl Copy { x }
| ^^^^^^^^^
help: to declare that the `impl Trait` captures data from argument `x`, you can add an explicit `'a` lifetime bound
|
LL | fn explicit<'a>(x: &'a i32) -> impl Copy + 'a { x }
| ^^^^
error: cannot infer an appropriate lifetime
--> $DIR/must_outlive_least_region_or_bound.rs:12:69
error[E0759]: cannot infer an appropriate lifetime
--> $DIR/must_outlive_least_region_or_bound.rs:9:46
|
LL | fn elided2(x: &i32) -> impl Copy + 'static { x }
| ---- ^ ...is captured here...
| |
| this data with an anonymous lifetime `'_`...
|
note: ...and is required to live as long as `'static` here
--> $DIR/must_outlive_least_region_or_bound.rs:9:24
|
LL | fn elided2(x: &i32) -> impl Copy + 'static { x }
| ^^^^^^^^^^^^^^^^^^^
help: consider changing the `impl Trait`'s explicit `'static` bound to the lifetime of argument `x`
|
LL | fn elided2(x: &i32) -> impl Copy + '_ { x }
| ^^
help: alternatively, add an explicit `'static` bound to this reference
|
LL | fn elided2(x: &'static i32) -> impl Copy + 'static { x }
| ^^^^^^^^^^^^
error[E0759]: cannot infer an appropriate lifetime
--> $DIR/must_outlive_least_region_or_bound.rs:12:55
|
LL | fn explicit2<'a>(x: &'a i32) -> impl Copy + 'static { x }
| ------- ^ ...is captured here...
| |
| this data with lifetime `'a`...
|
note: ...and is required to live as long as `'static` here
--> $DIR/must_outlive_least_region_or_bound.rs:12:33
|
LL | fn explicit2<'a>(x: &'a i32) -> impl Copy + 'static { x }
| ^^^^^^^^^^^^^^^^^^^
help: consider changing the `impl Trait`'s explicit `'static` bound to the lifetime of argument `x`
|
LL | fn explicit2<'a>(x: &'a i32) -> impl Copy + 'a { x }
| ^^
help: alternatively, add an explicit `'static` bound to this reference
|
LL | fn explicit2<'a>(x: &'static i32) -> impl Copy + 'static { x }
| ^^^^^^^^^^^^
error[E0621]: explicit lifetime required in the type of `x`
--> $DIR/must_outlive_least_region_or_bound.rs:15:24
|
LL | fn foo<'a>(x: &i32) -> impl Copy + 'a { x }
| ---- ^^^^^^^^^^^^^^ lifetime `'a` required
| |
| help: add explicit lifetime `'a` to the type of `x`: `&'a i32`
error[E0759]: cannot infer an appropriate lifetime
--> $DIR/must_outlive_least_region_or_bound.rs:33:69
|
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`... ^ ...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 function body at 12:15
note: ...and is required to live as long as `'static` here
--> $DIR/must_outlive_least_region_or_bound.rs:33:34
|
LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'static + 'a { x }
| ^^^^
LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'static { x }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
help: consider changing the `impl Trait`'s explicit `'static` bound to the lifetime of argument `x`
|
LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'a { x }
| ^^
help: alternatively, add an explicit `'static` bound to this reference
|
LL | fn with_bound<'a>(x: &'static i32) -> impl LifetimeTrait<'a> + 'static { x }
| ^^^^^^^^^^^^
error[E0623]: lifetime mismatch
--> $DIR/must_outlive_least_region_or_bound.rs:17:61
--> $DIR/must_outlive_least_region_or_bound.rs:38:61
|
LL | fn move_lifetime_into_fn<'a, 'b>(x: &'a u32, y: &'b u32) -> impl Fn(&'a u32) {
| ------- ^^^^^^^^^^^^^^^^
@ -50,14 +116,72 @@ LL | fn move_lifetime_into_fn<'a, 'b>(x: &'a u32, y: &'b u32) -> impl Fn(&'a u32
| this parameter and the return type are declared with different lifetimes...
error[E0310]: the parameter type `T` may not live long enough
--> $DIR/must_outlive_least_region_or_bound.rs:22:51
--> $DIR/must_outlive_least_region_or_bound.rs:43:51
|
LL | fn ty_param_wont_outlive_static<T:Debug>(x: T) -> impl Debug + 'static {
| -- ^^^^^^^^^^^^^^^^^^^^ ...so that the type `T` will meet its required lifetime bounds
| |
| help: consider adding an explicit lifetime bound...: `T: 'static +`
error: aborting due to 5 previous errors
error[E0759]: cannot infer an appropriate lifetime
--> $DIR/must_outlive_least_region_or_bound.rs:18:50
|
LL | fn elided3(x: &i32) -> Box<dyn Debug> { Box::new(x) }
| ---- ^ ...is captured here, requiring it to live as long as `'static`
| |
| this data with an anonymous lifetime `'_`...
|
help: to declare that the trait object captures data from argument `x`, you can add an explicit `'_` lifetime bound
|
LL | fn elided3(x: &i32) -> Box<dyn Debug + '_> { Box::new(x) }
| ^^^^
Some errors have detailed explanations: E0310, E0623.
error[E0759]: cannot infer an appropriate lifetime
--> $DIR/must_outlive_least_region_or_bound.rs:21:59
|
LL | fn explicit3<'a>(x: &'a i32) -> Box<dyn Debug> { Box::new(x) }
| ------- ^ ...is captured here, requiring it to live as long as `'static`
| |
| this data with lifetime `'a`...
|
help: to declare that the trait object captures data from argument `x`, you can add an explicit `'a` lifetime bound
|
LL | fn explicit3<'a>(x: &'a i32) -> Box<dyn Debug + 'a> { Box::new(x) }
| ^^^^
error[E0759]: cannot infer an appropriate lifetime
--> $DIR/must_outlive_least_region_or_bound.rs:24:60
|
LL | fn elided4(x: &i32) -> Box<dyn Debug + 'static> { Box::new(x) }
| ---- ^ ...is captured here, requiring it to live as long as `'static`
| |
| this data with an anonymous lifetime `'_`...
|
help: consider changing the trait object's explicit `'static` bound to the lifetime of argument `x`
|
LL | fn elided4(x: &i32) -> Box<dyn Debug + '_> { Box::new(x) }
| ^^
help: alternatively, add an explicit `'static` bound to this reference
|
LL | fn elided4(x: &'static i32) -> Box<dyn Debug + 'static> { Box::new(x) }
| ^^^^^^^^^^^^
error[E0759]: cannot infer an appropriate lifetime
--> $DIR/must_outlive_least_region_or_bound.rs:27:69
|
LL | fn explicit4<'a>(x: &'a i32) -> Box<dyn Debug + 'static> { Box::new(x) }
| ------- this data with lifetime `'a`... ^ ...is captured here, requiring it to live as long as `'static`
|
help: consider changing the trait object's explicit `'static` bound to the lifetime of argument `x`
|
LL | fn explicit4<'a>(x: &'a i32) -> Box<dyn Debug + 'a> { Box::new(x) }
| ^^
help: alternatively, add an explicit `'static` bound to this reference
|
LL | fn explicit4<'a>(x: &'static i32) -> Box<dyn Debug + 'static> { Box::new(x) }
| ^^^^^^^^^^^^
error: aborting due to 12 previous errors
Some errors have detailed explanations: E0310, E0621, E0623, E0759.
For more information about an error, try `rustc --explain E0310`.

31
src/test/ui/impl-trait/static-return-lifetime-infered.stderr
View file

@ -1,36 +1,43 @@
error: cannot infer an appropriate lifetime
error[E0759]: cannot infer an appropriate lifetime
--> $DIR/static-return-lifetime-infered.rs:7:16
|
LL | fn iter_values_anon(&self) -> impl Iterator<Item=u32> {
| ----- ----------------------- ...is required to be `'static` by this...
| |
| data with this lifetime...
| ----- this data with an anonymous lifetime `'_`...
LL | self.x.iter().map(|a| a.0)
| ------ ^^^^
| |
| ...and is captured here
| ...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
note: ...and is required to live as long as `'static` here
--> $DIR/static-return-lifetime-infered.rs:6:35
|
LL | fn iter_values_anon(&self) -> impl Iterator<Item=u32> {
| ^^^^^^^^^^^^^^^^^^^^^^^
help: to declare that the `impl Trait` captures data from argument `self`, you can add an explicit `'_` lifetime bound
|
LL | fn iter_values_anon(&self) -> impl Iterator<Item=u32> + '_ {
| ^^^^
error: cannot infer an appropriate lifetime
error[E0759]: cannot infer an appropriate lifetime
--> $DIR/static-return-lifetime-infered.rs:11:16
|
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
| ...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
note: ...and is required to live as long as `'static` here
--> $DIR/static-return-lifetime-infered.rs:10:37
|
LL | fn iter_values<'a>(&'a self) -> impl Iterator<Item=u32> {
| ^^^^^^^^^^^^^^^^^^^^^^^
help: to declare that the `impl Trait` captures data from argument `self`, you can add an explicit `'a` lifetime bound
|
LL | fn iter_values<'a>(&'a self) -> impl Iterator<Item=u32> + 'a {
| ^^^^
error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0759`.