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estebankestebank
committedJul 20, 2020
Detect when 'static obligation might come from an impl
Address #71341.
1 parent f9a3086 commit 0ced817

13 files changed

+431
-302
lines changed
 

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

+270-195
Large diffs are not rendered by default.

‎src/test/ui/associated-types/cache/project-fn-ret-contravariant.rs

+1-1
Original file line numberDiff line numberDiff line change
@@ -35,7 +35,7 @@ fn baz<'a,'b>(x: &'a u32, y: &'b u32) -> (&'a u32, &'b u32) {
3535

3636
#[cfg(transmute)] // one instantiations: BAD
3737
fn baz<'a,'b>(x: &'a u32) -> &'static u32 {
38-
bar(foo, x) //[transmute]~ ERROR E0495
38+
bar(foo, x) //[transmute]~ ERROR E0759
3939
}
4040

4141
#[cfg(krisskross)] // two instantiations, mixing and matching: BAD

‎src/test/ui/associated-types/cache/project-fn-ret-contravariant.transmute.stderr

+4-19
Original file line numberDiff line numberDiff line change
@@ -1,26 +1,11 @@
1-
error[E0495]: cannot infer an appropriate lifetime due to conflicting requirements
1+
error[E0759]: cannot infer an appropriate lifetime
22
--> $DIR/project-fn-ret-contravariant.rs:38:8
33
|
4-
LL | bar(foo, x)
5-
| ^^^
6-
|
7-
note: first, the lifetime cannot outlive the lifetime `'a` as defined on the function body at 37:8...
8-
--> $DIR/project-fn-ret-contravariant.rs:37:8
9-
|
104
LL | fn baz<'a,'b>(x: &'a u32) -> &'static u32 {
11-
| ^^
12-
note: ...so that reference does not outlive borrowed content
13-
--> $DIR/project-fn-ret-contravariant.rs:38:13
14-
|
15-
LL | bar(foo, x)
16-
| ^
17-
= note: but, the lifetime must be valid for the static lifetime...
18-
note: ...so that reference does not outlive borrowed content
19-
--> $DIR/project-fn-ret-contravariant.rs:38:4
20-
|
5+
| ------- this data with lifetime `'a`...
216
LL | bar(foo, x)
22-
| ^^^^^^^^^^^
7+
| ----^^^---- ...is captured and required to live as long as `'static` here
238

249
error: aborting due to previous error
2510

26-
For more information about this error, try `rustc --explain E0495`.
11+
For more information about this error, try `rustc --explain E0759`.

‎src/test/ui/associated-types/cache/project-fn-ret-invariant.rs

+1-1
Original file line numberDiff line numberDiff line change
@@ -46,7 +46,7 @@ fn baz<'a, 'b>(x: Type<'a>) -> Type<'static> {
4646
// Cannot instantiate `foo` with any lifetime other than `'a`,
4747
// since it is provided as input.
4848

49-
bar(foo, x) //[transmute]~ ERROR E0495
49+
bar(foo, x) //[transmute]~ ERROR E0759
5050
}
5151

5252
#[cfg(krisskross)] // two instantiations, mixing and matching: BAD

‎src/test/ui/associated-types/cache/project-fn-ret-invariant.transmute.stderr

+5-23
Original file line numberDiff line numberDiff line change
@@ -1,30 +1,12 @@
1-
error[E0495]: cannot infer an appropriate lifetime for lifetime parameter `'a` due to conflicting requirements
1+
error[E0759]: cannot infer an appropriate lifetime
22
--> $DIR/project-fn-ret-invariant.rs:49:9
33
|
4-
LL | bar(foo, x)
5-
| ^^^
6-
|
7-
note: first, the lifetime cannot outlive the lifetime `'a` as defined on the function body at 45:8...
8-
--> $DIR/project-fn-ret-invariant.rs:45:8
9-
|
104
LL | fn baz<'a, 'b>(x: Type<'a>) -> Type<'static> {
11-
| ^^
12-
note: ...so that the expression is assignable
13-
--> $DIR/project-fn-ret-invariant.rs:49:14
14-
|
15-
LL | bar(foo, x)
16-
| ^
17-
= note: expected `Type<'_>`
18-
found `Type<'a>`
19-
= note: but, the lifetime must be valid for the static lifetime...
20-
note: ...so that the expression is assignable
21-
--> $DIR/project-fn-ret-invariant.rs:49:5
22-
|
5+
| -------- this data with lifetime `'a`...
6+
...
237
LL | bar(foo, x)
24-
| ^^^^^^^^^^^
25-
= note: expected `Type<'static>`
26-
found `Type<'_>`
8+
| ----^^^---- ...is captured and required to live as long as `'static` here
279

2810
error: aborting due to previous error
2911

30-
For more information about this error, try `rustc --explain E0495`.
12+
For more information about this error, try `rustc --explain E0759`.

‎src/test/ui/impl-header-lifetime-elision/dyn-trait.stderr

+6-19
Original file line numberDiff line numberDiff line change
@@ -1,30 +1,17 @@
1-
error[E0495]: cannot infer an appropriate lifetime due to conflicting requirements
1+
error[E0759]: cannot infer an appropriate lifetime
22
--> $DIR/dyn-trait.rs:20:16
33
|
4-
LL | static_val(x);
5-
| ^
6-
|
7-
note: first, the lifetime cannot outlive the lifetime `'a` as defined on the function body at 19:26...
8-
--> $DIR/dyn-trait.rs:19:26
9-
|
104
LL | fn with_dyn_debug_static<'a>(x: Box<dyn Debug + 'a>) {
11-
| ^^
12-
note: ...so that the expression is assignable
13-
--> $DIR/dyn-trait.rs:20:16
14-
|
5+
| ------------------- this data with lifetime `'a`...
156
LL | static_val(x);
16-
| ^
17-
= note: expected `std::boxed::Box<dyn std::fmt::Debug>`
18-
found `std::boxed::Box<(dyn std::fmt::Debug + 'a)>`
19-
= note: but, the lifetime must be valid for the static lifetime...
20-
note: ...so that the types are compatible
7+
| ^ ...is captured here...
8+
|
9+
note: ...and is required to live as long as `'static` here
2110
--> $DIR/dyn-trait.rs:20:5
2211
|
2312
LL | static_val(x);
2413
| ^^^^^^^^^^
25-
= note: expected `StaticTrait`
26-
found `StaticTrait`
2714

2815
error: aborting due to previous error
2916

30-
For more information about this error, try `rustc --explain E0495`.
17+
For more information about this error, try `rustc --explain E0759`.

‎src/test/ui/nll/user-annotations/constant-in-expr-inherent-1.stderr

+4-21
Original file line numberDiff line numberDiff line change
@@ -1,28 +1,11 @@
1-
error[E0495]: cannot infer an appropriate lifetime for lifetime parameter `'a` due to conflicting requirements
1+
error[E0759]: cannot infer an appropriate lifetime
22
--> $DIR/constant-in-expr-inherent-1.rs:8:5
33
|
4-
LL | <Foo<'a>>::C
5-
| ^^^^^^^^^^^^
6-
|
7-
note: first, the lifetime cannot outlive the lifetime `'a` as defined on the function body at 7:8...
8-
--> $DIR/constant-in-expr-inherent-1.rs:7:8
9-
|
104
LL | fn foo<'a>(_: &'a u32) -> &'static u32 {
11-
| ^^
12-
note: ...so that the types are compatible
13-
--> $DIR/constant-in-expr-inherent-1.rs:8:5
14-
|
15-
LL | <Foo<'a>>::C
16-
| ^^^^^^^^^^^^
17-
= note: expected `Foo<'_>`
18-
found `Foo<'a>`
19-
= note: but, the lifetime must be valid for the static lifetime...
20-
note: ...so that reference does not outlive borrowed content
21-
--> $DIR/constant-in-expr-inherent-1.rs:8:5
22-
|
5+
| ------- this data with lifetime `'a`...
236
LL | <Foo<'a>>::C
24-
| ^^^^^^^^^^^^
7+
| ^^^^^^^^^^^^ ...is captured and required to live as long as `'static` here
258

269
error: aborting due to previous error
2710

28-
For more information about this error, try `rustc --explain E0495`.
11+
For more information about this error, try `rustc --explain E0759`.

‎src/test/ui/regions/regions-addr-of-self.stderr

+5-23
Original file line numberDiff line numberDiff line change
@@ -1,29 +1,11 @@
1-
error[E0495]: cannot infer an appropriate lifetime for borrow expression due to conflicting requirements
1+
error[E0759]: cannot infer an appropriate lifetime
22
--> $DIR/regions-addr-of-self.rs:7:37
33
|
4+
LL | pub fn chase_cat(&mut self) {
5+
| --------- this data with an anonymous lifetime `'_`...
46
LL | let p: &'static mut usize = &mut self.cats_chased;
5-
| ^^^^^^^^^^^^^^^^^^^^^
6-
|
7-
note: first, the lifetime cannot outlive the anonymous lifetime #1 defined on the method body at 6:5...
8-
--> $DIR/regions-addr-of-self.rs:6:5
9-
|
10-
LL | / pub fn chase_cat(&mut self) {
11-
LL | | let p: &'static mut usize = &mut self.cats_chased;
12-
LL | | *p += 1;
13-
LL | | }
14-
| |_____^
15-
note: ...so that reference does not outlive borrowed content
16-
--> $DIR/regions-addr-of-self.rs:7:37
17-
|
18-
LL | let p: &'static mut usize = &mut self.cats_chased;
19-
| ^^^^^^^^^^^^^^^^^^^^^
20-
= note: but, the lifetime must be valid for the static lifetime...
21-
note: ...so that reference does not outlive borrowed content
22-
--> $DIR/regions-addr-of-self.rs:7:37
23-
|
24-
LL | let p: &'static mut usize = &mut self.cats_chased;
25-
| ^^^^^^^^^^^^^^^^^^^^^
7+
| ^^^^^^^^^^^^^^^^^^^^^ ...is captured and required to live as long as `'static` here
268

279
error: aborting due to previous error
2810

29-
For more information about this error, try `rustc --explain E0495`.
11+
For more information about this error, try `rustc --explain E0759`.

‎src/test/ui/suggestions/impl-on-dyn-trait-with-implicit-static-bound-without-suggestion.rs

+14
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,14 @@
1+
trait OtherTrait<'a> {}
2+
impl<'a> OtherTrait<'a> for &'a () {}
3+
4+
trait ObjectTrait {}
5+
6+
impl dyn ObjectTrait {
7+
fn use_self(&self) -> &() { panic!() }
8+
}
9+
10+
fn use_it<'a>(val: &'a dyn ObjectTrait) -> impl OtherTrait<'a> + 'a {
11+
val.use_self() //~ ERROR mismatched types
12+
}
13+
14+
fn main() {}

‎src/test/ui/suggestions/impl-on-dyn-trait-with-implicit-static-bound-without-suggestion.stderr

+18
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,18 @@
1+
error[E0308]: mismatched types
2+
--> $DIR/impl-on-dyn-trait-with-implicit-static-bound-without-suggestion.rs:11:9
3+
|
4+
LL | val.use_self()
5+
| ^^^^^^^^ lifetime mismatch
6+
|
7+
= note: expected reference `&(dyn ObjectTrait + 'static)`
8+
found reference `&(dyn ObjectTrait + 'a)`
9+
note: the lifetime `'a` as defined on the function body at 10:11...
10+
--> $DIR/impl-on-dyn-trait-with-implicit-static-bound-without-suggestion.rs:10:11
11+
|
12+
LL | fn use_it<'a>(val: &'a dyn ObjectTrait) -> impl OtherTrait<'a> + 'a {
13+
| ^^
14+
= note: ...does not necessarily outlive the static lifetime
15+
16+
error: aborting due to previous error
17+
18+
For more information about this error, try `rustc --explain E0308`.

‎src/test/ui/suggestions/impl-on-dyn-trait-with-implicit-static-bound.fixed

+37
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,37 @@
1+
// run-rustfix
2+
#![allow(dead_code)]
3+
4+
mod foo {
5+
trait OtherTrait<'a> {}
6+
impl<'a> OtherTrait<'a> for &'a () {}
7+
8+
trait ObjectTrait {}
9+
trait MyTrait {
10+
fn use_self(&self) -> &();
11+
}
12+
13+
impl MyTrait for dyn ObjectTrait + '_ {
14+
fn use_self(&self) -> &() { panic!() }
15+
}
16+
17+
fn use_it<'a>(val: &'a dyn ObjectTrait) -> impl OtherTrait<'a> + 'a {
18+
val.use_self() //~ ERROR cannot infer an appropriate lifetime
19+
}
20+
}
21+
22+
mod bar {
23+
trait ObjectTrait {}
24+
trait MyTrait {
25+
fn use_self(&self) -> &();
26+
}
27+
28+
impl MyTrait for dyn ObjectTrait + '_ {
29+
fn use_self(&self) -> &() { panic!() }
30+
}
31+
32+
fn use_it<'a>(val: &'a dyn ObjectTrait) -> &'a () {
33+
val.use_self() //~ ERROR cannot infer an appropriate lifetime
34+
}
35+
}
36+
37+
fn main() {}

‎src/test/ui/suggestions/impl-on-dyn-trait-with-implicit-static-bound.rs

+37
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,37 @@
1+
// run-rustfix
2+
#![allow(dead_code)]
3+
4+
mod foo {
5+
trait OtherTrait<'a> {}
6+
impl<'a> OtherTrait<'a> for &'a () {}
7+
8+
trait ObjectTrait {}
9+
trait MyTrait {
10+
fn use_self(&self) -> &();
11+
}
12+
13+
impl MyTrait for dyn ObjectTrait {
14+
fn use_self(&self) -> &() { panic!() }
15+
}
16+
17+
fn use_it<'a>(val: &'a dyn ObjectTrait) -> impl OtherTrait<'a> + 'a {
18+
val.use_self() //~ ERROR cannot infer an appropriate lifetime
19+
}
20+
}
21+
22+
mod bar {
23+
trait ObjectTrait {}
24+
trait MyTrait {
25+
fn use_self(&self) -> &();
26+
}
27+
28+
impl MyTrait for dyn ObjectTrait {
29+
fn use_self(&self) -> &() { panic!() }
30+
}
31+
32+
fn use_it<'a>(val: &'a dyn ObjectTrait) -> &'a () {
33+
val.use_self() //~ ERROR cannot infer an appropriate lifetime
34+
}
35+
}
36+
37+
fn main() {}

‎src/test/ui/suggestions/impl-on-dyn-trait-with-implicit-static-bound.stderr

+29
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,29 @@
1+
error[E0759]: cannot infer an appropriate lifetime
2+
--> $DIR/impl-on-dyn-trait-with-implicit-static-bound.rs:18:13
3+
|
4+
LL | fn use_it<'a>(val: &'a dyn ObjectTrait) -> impl OtherTrait<'a> + 'a {
5+
| ------------------- this data with lifetime `'a`...
6+
LL | val.use_self()
7+
| ^^^^^^^^ ...is captured and required to live as long as `'static` here
8+
|
9+
help: this `impl` introduces an implicit `'static` requirement, consider changing it
10+
|
11+
LL | impl MyTrait for dyn ObjectTrait + '_ {
12+
| ^^^^
13+
14+
error[E0759]: cannot infer an appropriate lifetime
15+
--> $DIR/impl-on-dyn-trait-with-implicit-static-bound.rs:33:13
16+
|
17+
LL | fn use_it<'a>(val: &'a dyn ObjectTrait) -> &'a () {
18+
| ------------------- this data with lifetime `'a`...
19+
LL | val.use_self()
20+
| ^^^^^^^^ ...is captured and required to live as long as `'static` here
21+
|
22+
help: this `impl` introduces an implicit `'static` requirement, consider changing it
23+
|
24+
LL | impl MyTrait for dyn ObjectTrait + '_ {
25+
| ^^^^
26+
27+
error: aborting due to 2 previous errors
28+
29+
For more information about this error, try `rustc --explain E0759`.

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