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add even more tests for ptr-to-ptr casts on trait objects

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This commit is contained in:
Lukas Markeffsky 2024-09-27 19:27:48 +02:00
parent a3f76a26e0
commit 8302f2e35f
4 changed files with 92 additions and 7 deletions
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6
tests/ui/cast/ptr-to-trait-obj-different-regions-misc.rs
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@ -15,6 +15,12 @@ fn change_lt_ba<'a, 'b: 'a>(x: *mut dyn Trait<'a>) -> *mut dyn Trait<'b> {
x as _ //~ error: lifetime may not live long enough
}
fn change_lt_hr<'a>(x: *mut dyn Trait<'a>) -> *mut dyn for<'b> Trait<'b> {
x as _ //~ error: lifetime may not live long enough
//~^ error: mismatched types
//~| one type is more general than the other
}
trait Assocked {
type Assoc: ?Sized;
}

35
tests/ui/cast/ptr-to-trait-obj-different-regions-misc.stderr
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@ -61,7 +61,29 @@ LL | x as _
= help: see <https://doc.rust-lang.org/nomicon/subtyping.html> for more information about variance
error: lifetime may not live long enough
--> $DIR/ptr-to-trait-obj-different-regions-misc.rs:25:5
--> $DIR/ptr-to-trait-obj-different-regions-misc.rs:19:5
|
LL | fn change_lt_hr<'a>(x: *mut dyn Trait<'a>) -> *mut dyn for<'b> Trait<'b> {
| -- lifetime `'a` defined here
LL | x as _
| ^^^^^^ cast requires that `'a` must outlive `'static`
|
help: to declare that the trait object captures data from argument `x`, you can add an explicit `'a` lifetime bound
|
LL | fn change_lt_hr<'a>(x: *mut dyn Trait<'a>) -> *mut dyn for<'b> Trait<'b> + 'a {
| ++++
error[E0308]: mismatched types
--> $DIR/ptr-to-trait-obj-different-regions-misc.rs:19:5
|
LL | x as _
| ^^^^^^ one type is more general than the other
|
= note: expected trait object `dyn for<'b> Trait<'b>`
found trait object `dyn Trait<'_>`
error: lifetime may not live long enough
--> $DIR/ptr-to-trait-obj-different-regions-misc.rs:31:5
|
LL | fn change_assoc_0<'a, 'b>(
| -- -- lifetime `'b` defined here
@ -77,7 +99,7 @@ LL | x as _
= help: see <https://doc.rust-lang.org/nomicon/subtyping.html> for more information about variance
error: lifetime may not live long enough
--> $DIR/ptr-to-trait-obj-different-regions-misc.rs:25:5
--> $DIR/ptr-to-trait-obj-different-regions-misc.rs:31:5
|
LL | fn change_assoc_0<'a, 'b>(
| -- -- lifetime `'b` defined here
@ -97,7 +119,7 @@ help: `'b` and `'a` must be the same: replace one with the other
= note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
error: lifetime may not live long enough
--> $DIR/ptr-to-trait-obj-different-regions-misc.rs:32:5
--> $DIR/ptr-to-trait-obj-different-regions-misc.rs:38:5
|
LL | fn change_assoc_1<'a, 'b>(
| -- -- lifetime `'b` defined here
@ -113,7 +135,7 @@ LL | x as _
= help: see <https://doc.rust-lang.org/nomicon/subtyping.html> for more information about variance
error: lifetime may not live long enough
--> $DIR/ptr-to-trait-obj-different-regions-misc.rs:32:5
--> $DIR/ptr-to-trait-obj-different-regions-misc.rs:38:5
|
LL | fn change_assoc_1<'a, 'b>(
| -- -- lifetime `'b` defined here
@ -133,12 +155,13 @@ help: `'b` and `'a` must be the same: replace one with the other
= note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
error: lifetime may not live long enough
--> $DIR/ptr-to-trait-obj-different-regions-misc.rs:39:20
--> $DIR/ptr-to-trait-obj-different-regions-misc.rs:45:20
|
LL | fn extend_to_static<'a>(ptr: *const dyn Trait<'a>) {
| -- lifetime `'a` defined here
LL | require_static(ptr as _)
| ^^^^^^^^ cast requires that `'a` must outlive `'static`
error: aborting due to 9 previous errors
error: aborting due to 11 previous errors
For more information about this error, try `rustc --explain E0308`.

34
tests/ui/cast/ptr-to-trait-obj-ok.rs
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@ -1,4 +1,4 @@
//@ check-pass
//@ check-fail
trait Trait<'a> {}
@ -10,8 +10,40 @@ fn cast_inherent_lt<'a, 'b>(x: *mut (dyn Trait<'static> + 'a)) -> *mut (dyn Trai
x as _
}
fn cast_away_higher_ranked<'a>(x: *mut dyn for<'b> Trait<'b>) -> *mut dyn Trait<'a> {
x as _
}
fn unprincipled<'a, 'b>(x: *mut (dyn Send + 'a)) -> *mut (dyn Sync + 'b) {
x as _
}
// If it is possible to coerce from the source to the target type modulo
// regions, then we skip the HIR checks for ptr-to-ptr casts and possibly
// insert an unsizing coercion into the MIR before the ptr-to-ptr cast.
// By wrapping the target type, we ensure that no coercion happens
// and also test the non-coercion cast behavior.
struct Wrapper<T: ?Sized>(T);
fn remove_auto_wrap<'a>(x: *mut (dyn Trait<'a> + Send)) -> *mut Wrapper<dyn Trait<'a>> {
x as _
}
fn cast_inherent_lt_wrap<'a, 'b>(
x: *mut (dyn Trait<'static> + 'a),
) -> *mut Wrapper<dyn Trait<'static> + 'b> {
x as _
}
fn cast_away_higher_ranked_wrap<'a>(x: *mut dyn for<'b> Trait<'b>) -> *mut Wrapper<dyn Trait<'a>> {
x as _
//~^ error: lifetime may not live long enough
//~| error: mismatched types
//~| one type is more general than the other
}
fn unprincipled_wrap<'a, 'b>(x: *mut (dyn Send + 'a)) -> *mut Wrapper<dyn Sync + 'b> {
x as _
}
fn main() {}

24
tests/ui/cast/ptr-to-trait-obj-ok.stderr Normal file
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@ -0,0 +1,24 @@
error: lifetime may not live long enough
--> $DIR/ptr-to-trait-obj-ok.rs:39:5
|
LL | fn cast_away_higher_ranked_wrap<'a>(x: *mut dyn for<'b> Trait<'b>) -> *mut Wrapper<dyn Trait<'a>> {
| -- lifetime `'a` defined here
LL | x as _
| ^^^^^^ returning this value requires that `'a` must outlive `'static`
|
= note: requirement occurs because of a mutable pointer to `Wrapper<dyn Trait<'_>>`
= note: mutable pointers are invariant over their type parameter
= help: see <https://doc.rust-lang.org/nomicon/subtyping.html> for more information about variance
error[E0308]: mismatched types
--> $DIR/ptr-to-trait-obj-ok.rs:39:5
|
LL | x as _
| ^^^^^^ one type is more general than the other
|
= note: expected trait object `dyn for<'b> Trait<'b>`
found trait object `dyn Trait<'_>`
error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0308`.