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trait_sel: MetaSized always holds temporarily

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As a temporary measure while a proper fix for
`tests/ui/sized-hierarchy/incomplete-inference-issue-143992.rs`
is implemented, make `MetaSized` obligations always hold. In effect,
temporarily reverting the `sized_hierarchy` feature. This is a small
change that can be backported.
This commit is contained in:
David Wood
2025-07-16 10:56:32 +00:00
parent 231257f583
commit 8d64937dc2
19 changed files with 77 additions and 244 deletions
Download Patch File Download Diff File Expand all files Collapse all files
compiler/rustc_trait_selection/src/traits/util.rs
+7
View File
@@ -378,6 +378,13 @@ pub fn sizedness_fast_path<'tcx>(tcx: TyCtxt<'tcx>, predicate: ty::Predicate<'tc
_ => return false,
};
// FIXME(sized_hierarchy): this temporarily reverts the `sized_hierarchy` feature
// while a proper fix for `tests/ui/sized-hierarchy/incomplete-inference-issue-143992.rs`
// is pending a proper fix
if !tcx.features().sized_hierarchy() && matches!(sizedness, SizedTraitKind::MetaSized) {
return true;
}
if trait_pred.self_ty().has_trivial_sizedness(tcx, sizedness) {
debug!("fast path -- trivial sizedness");
return true;
tests/ui/consts/const-size_of_val-align_of_val-extern-type.rs
+2 -2
View File
@@ -8,8 +8,8 @@
}
const _SIZE: usize = unsafe { size_of_val(&4 as *const i32 as *const Opaque) };
//~^ ERROR the size for values of type `Opaque` cannot be known
//~^ ERROR `extern type` does not have known layout
const _ALIGN: usize = unsafe { align_of_val(&4 as *const i32 as *const Opaque) };
//~^ ERROR the size for values of type `Opaque` cannot be known
//~^ ERROR `extern type` does not have known layout
fn main() {}
tests/ui/consts/const-size_of_val-align_of_val-extern-type.stderr
+7 -31
View File
@@ -1,39 +1,15 @@
error[E0277]: the size for values of type `Opaque` cannot be known
--> $DIR/const-size_of_val-align_of_val-extern-type.rs:10:43
error[E0080]: `extern type` does not have known layout
--> $DIR/const-size_of_val-align_of_val-extern-type.rs:10:31
|
LL | const _SIZE: usize = unsafe { size_of_val(&4 as *const i32 as *const Opaque) };
| ----------- ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `MetaSized` is not implemented for `Opaque`
| |
| required by a bound introduced by this call
|
= note: the trait bound `Opaque: MetaSized` is not satisfied
note: required by a bound in `std::intrinsics::size_of_val`
--> $SRC_DIR/core/src/intrinsics/mod.rs:LL:COL
help: consider borrowing here
|
LL | const _SIZE: usize = unsafe { size_of_val(&(&4 as *const i32 as *const Opaque)) };
| ++ +
LL | const _SIZE: usize = unsafe { size_of_val(&mut (&4 as *const i32 as *const Opaque)) };
| ++++++ +
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of `_SIZE` failed here
error[E0277]: the size for values of type `Opaque` cannot be known
--> $DIR/const-size_of_val-align_of_val-extern-type.rs:12:45
error[E0080]: `extern type` does not have known layout
--> $DIR/const-size_of_val-align_of_val-extern-type.rs:12:32
|
LL | const _ALIGN: usize = unsafe { align_of_val(&4 as *const i32 as *const Opaque) };
| ------------ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `MetaSized` is not implemented for `Opaque`
| |
| required by a bound introduced by this call
|
= note: the trait bound `Opaque: MetaSized` is not satisfied
note: required by a bound in `std::intrinsics::align_of_val`
--> $SRC_DIR/core/src/intrinsics/mod.rs:LL:COL
help: consider borrowing here
|
LL | const _ALIGN: usize = unsafe { align_of_val(&(&4 as *const i32 as *const Opaque)) };
| ++ +
LL | const _ALIGN: usize = unsafe { align_of_val(&mut (&4 as *const i32 as *const Opaque)) };
| ++++++ +
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of `_ALIGN` failed here
error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0277`.
For more information about this error, try `rustc --explain E0080`.
tests/ui/extern/extern-types-size_of_val.rs
Vendored
+1 -3
View File
@@ -1,4 +1,4 @@
//@ check-fail
//@ check-pass
#![feature(extern_types)]
use std::mem::{align_of_val, size_of_val};
@@ -11,7 +11,5 @@ fn main() {
let x: &A = unsafe { &*(1usize as *const A) };
size_of_val(x);
//~^ ERROR the size for values of type `A` cannot be known
align_of_val(x);
//~^ ERROR the size for values of type `A` cannot be known
}
tests/ui/extern/extern-types-size_of_val.stderr
Vendored
-39
View File
@@ -1,39 +0,0 @@
error[E0277]: the size for values of type `A` cannot be known
--> $DIR/extern-types-size_of_val.rs:13:17
|
LL | size_of_val(x);
| ----------- ^ the trait `MetaSized` is not implemented for `A`
| |
| required by a bound introduced by this call
|
= note: the trait bound `A: MetaSized` is not satisfied
note: required by a bound in `std::mem::size_of_val`
--> $SRC_DIR/core/src/mem/mod.rs:LL:COL
help: consider borrowing here
|
LL | size_of_val(&x);
| +
LL | size_of_val(&mut x);
| ++++
error[E0277]: the size for values of type `A` cannot be known
--> $DIR/extern-types-size_of_val.rs:15:18
|
LL | align_of_val(x);
| ------------ ^ the trait `MetaSized` is not implemented for `A`
| |
| required by a bound introduced by this call
|
= note: the trait bound `A: MetaSized` is not satisfied
note: required by a bound in `std::mem::align_of_val`
--> $SRC_DIR/core/src/mem/mod.rs:LL:COL
help: consider borrowing here
|
LL | align_of_val(&x);
| +
LL | align_of_val(&mut x);
| ++++
error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0277`.
tests/ui/extern/extern-types-unsized.rs
Vendored
-2
View File
@@ -27,9 +27,7 @@ fn main() {
assert_sized::<Bar<A>>();
//~^ ERROR the size for values of type
//~| ERROR the size for values of type
assert_sized::<Bar<Bar<A>>>();
//~^ ERROR the size for values of type
//~| ERROR the size for values of type
}
tests/ui/extern/extern-types-unsized.stderr
Vendored
+2 -28
View File
@@ -59,21 +59,8 @@ help: consider relaxing the implicit `Sized` restriction
LL | fn assert_sized<T: ?Sized>() {}
| ++++++++
error[E0277]: the size for values of type `A` cannot be known
--> $DIR/extern-types-unsized.rs:28:20
|
LL | assert_sized::<Bar<A>>();
| ^^^^^^ doesn't have a known size
|
= help: the trait `MetaSized` is not implemented for `A`
note: required by a bound in `Bar`
--> $DIR/extern-types-unsized.rs:14:12
|
LL | struct Bar<T: ?Sized> {
| ^ required by this bound in `Bar`
error[E0277]: the size for values of type `A` cannot be known at compilation time
--> $DIR/extern-types-unsized.rs:32:20
--> $DIR/extern-types-unsized.rs:31:20
|
LL | assert_sized::<Bar<Bar<A>>>();
| ^^^^^^^^^^^ doesn't have a size known at compile-time
@@ -94,19 +81,6 @@ help: consider relaxing the implicit `Sized` restriction
LL | fn assert_sized<T: ?Sized>() {}
| ++++++++
error[E0277]: the size for values of type `A` cannot be known
--> $DIR/extern-types-unsized.rs:32:20
|
LL | assert_sized::<Bar<Bar<A>>>();
| ^^^^^^^^^^^ doesn't have a known size
|
= help: the trait `MetaSized` is not implemented for `A`
note: required by a bound in `Bar`
--> $DIR/extern-types-unsized.rs:14:12
|
LL | struct Bar<T: ?Sized> {
| ^ required by this bound in `Bar`
error: aborting due to 6 previous errors
error: aborting due to 4 previous errors
For more information about this error, try `rustc --explain E0277`.
tests/ui/extern/unsized-extern-derefmove.rs
Vendored
-4
View File
@@ -7,14 +7,10 @@
}
unsafe fn make_device() -> Box<Device> {
//~^ ERROR the size for values of type `Device` cannot be known
Box::from_raw(0 as *mut _)
//~^ ERROR the size for values of type `Device` cannot be known
//~| ERROR the size for values of type `Device` cannot be known
}
fn main() {
let d: Device = unsafe { *make_device() };
//~^ ERROR the size for values of type `Device` cannot be known
//~| ERROR the size for values of type `Device` cannot be known
}
tests/ui/extern/unsized-extern-derefmove.stderr
Vendored
+2 -50
View File
@@ -1,43 +1,5 @@
error[E0277]: the size for values of type `Device` cannot be known
--> $DIR/unsized-extern-derefmove.rs:9:28
|
LL | unsafe fn make_device() -> Box<Device> {
| ^^^^^^^^^^^ doesn't have a known size
|
= help: the trait `MetaSized` is not implemented for `Device`
note: required by a bound in `Box`
--> $SRC_DIR/alloc/src/boxed.rs:LL:COL
error[E0277]: the size for values of type `Device` cannot be known
--> $DIR/unsized-extern-derefmove.rs:11:19
|
LL | Box::from_raw(0 as *mut _)
| ------------- ^^^^^^^^^^^ the trait `MetaSized` is not implemented for `Device`
| |
| required by a bound introduced by this call
|
= note: the trait bound `Device: MetaSized` is not satisfied
note: required by a bound in `Box::<T>::from_raw`
--> $SRC_DIR/alloc/src/boxed.rs:LL:COL
help: consider borrowing here
|
LL | Box::from_raw(&(0 as *mut _))
| ++ +
LL | Box::from_raw(&mut (0 as *mut _))
| ++++++ +
error[E0277]: the size for values of type `Device` cannot be known
--> $DIR/unsized-extern-derefmove.rs:11:5
|
LL | Box::from_raw(0 as *mut _)
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ doesn't have a known size
|
= help: the trait `MetaSized` is not implemented for `Device`
note: required by a bound in `Box`
--> $SRC_DIR/alloc/src/boxed.rs:LL:COL
error[E0277]: the size for values of type `Device` cannot be known at compilation time
--> $DIR/unsized-extern-derefmove.rs:17:9
--> $DIR/unsized-extern-derefmove.rs:14:9
|
LL | let d: Device = unsafe { *make_device() };
| ^ doesn't have a size known at compile-time
@@ -49,16 +11,6 @@ help: consider borrowing here
LL | let d: &Device = unsafe { *make_device() };
| +
error[E0277]: the size for values of type `Device` cannot be known
--> $DIR/unsized-extern-derefmove.rs:17:31
|
LL | let d: Device = unsafe { *make_device() };
| ^^^^^^^^^^^^^ doesn't have a known size
|
= help: the trait `MetaSized` is not implemented for `Device`
note: required by a bound in `Box`
--> $SRC_DIR/alloc/src/boxed.rs:LL:COL
error: aborting due to 5 previous errors
error: aborting due to 1 previous error
For more information about this error, try `rustc --explain E0277`.
tests/ui/layout/unconstrained-param-ice-137308.rs
-1
View File
@@ -17,4 +17,3 @@ impl<C: ?Sized> A for u8 { //~ ERROR: the type parameter `C` is not constrained
#[rustc_layout(debug)]
struct S([u8; <u8 as A>::B]);
//~^ ERROR: the type has an unknown layout
//~| ERROR: type annotations needed
tests/ui/layout/unconstrained-param-ice-137308.stderr
+2 -9
View File
@@ -4,19 +4,12 @@ error[E0207]: the type parameter `C` is not constrained by the impl trait, self
LL | impl<C: ?Sized> A for u8 {
| ^ unconstrained type parameter
error[E0282]: type annotations needed
--> $DIR/unconstrained-param-ice-137308.rs:18:16
|
LL | struct S([u8; <u8 as A>::B]);
| ^^ cannot infer type for type parameter `C`
error: the type has an unknown layout
--> $DIR/unconstrained-param-ice-137308.rs:18:1
|
LL | struct S([u8; <u8 as A>::B]);
| ^^^^^^^^
error: aborting due to 3 previous errors
error: aborting due to 2 previous errors
Some errors have detailed explanations: E0207, E0282.
For more information about an error, try `rustc --explain E0207`.
For more information about this error, try `rustc --explain E0207`.
tests/ui/nll/issue-50716.rs
+1 -1
View File
@@ -5,7 +5,7 @@ trait A {
type X: ?Sized;
}
fn foo<'a, T: 'static>(s: Box<<&'a T as A>::X>) //~ ERROR
fn foo<'a, T: 'static>(s: Box<<&'a T as A>::X>)
where
for<'b> &'b T: A,
<&'static T as A>::X: Sized
tests/ui/nll/issue-50716.stderr
+1 -17
View File
@@ -1,18 +1,3 @@
error[E0308]: mismatched types
--> $DIR/issue-50716.rs:8:27
|
LL | fn foo<'a, T: 'static>(s: Box<<&'a T as A>::X>)
| ^^^^^^^^^^^^^^^^^^^^ lifetime mismatch
|
= note: expected trait `<<&'a T as A>::X as MetaSized>`
found trait `<<&'static T as A>::X as MetaSized>`
note: the lifetime `'a` as defined here...
--> $DIR/issue-50716.rs:8:8
|
LL | fn foo<'a, T: 'static>(s: Box<<&'a T as A>::X>)
| ^^
= note: ...does not necessarily outlive the static lifetime
error: lifetime may not live long enough
--> $DIR/issue-50716.rs:13:14
|
@@ -22,6 +7,5 @@ LL | fn foo<'a, T: 'static>(s: Box<<&'a T as A>::X>)
LL | let _x = *s;
| ^^ proving this value is `Sized` requires that `'a` must outlive `'static`
error: aborting due to 2 previous errors
error: aborting due to 1 previous error
For more information about this error, try `rustc --explain E0308`.
tests/ui/sized-hierarchy/incomplete-inference-issue-143992.next.stderr
+17
View File
@@ -0,0 +1,17 @@
error[E0308]: mismatched types
--> $DIR/incomplete-inference-issue-143992.rs:27:28
|
LL | let _x = T::Assoc::new(());
| ------------- ^^ expected `[u32; 1]`, found `()`
| |
| arguments to this function are incorrect
|
note: associated function defined here
--> $DIR/incomplete-inference-issue-143992.rs:18:8
|
LL | fn new(r: R) -> R {
| ^^^ ----
error: aborting due to 1 previous error
For more information about this error, try `rustc --explain E0308`.
tests/ui/sized-hierarchy/incomplete-inference-issue-143992.rs
+29
View File
@@ -0,0 +1,29 @@
//@ compile-flags: --crate-type=lib
//@ revisions: current next
//@ ignore-compare-mode-next-solver (explicit revisions)
//@[current] check-pass
//@[next] compile-flags: -Znext-solver
//@[next] check-fail
// Test that we avoid incomplete inference when normalizing. Without this,
// `Trait`'s implicit `MetaSized` supertrait requires proving `T::Assoc<_>: MetaSized`
// before checking the `new` arguments, resulting in eagerly constraining the inference
// var to `u32`. This is undesirable and would breaking code.
pub trait Trait {
type Assoc<G>: OtherTrait<G>;
}
pub trait OtherTrait<R> {
fn new(r: R) -> R {
r
}
}
pub fn function<T: Trait>()
where
T::Assoc<[u32; 1]>: Clone,
{
let _x = T::Assoc::new(());
//[next]~^ ERROR mismatched types
}
tests/ui/sized-hierarchy/overflow.current.stderr
-45
View File
@@ -1,45 +0,0 @@
error[E0275]: overflow evaluating the requirement `Element: MetaSized`
--> $DIR/overflow.rs:16:16
|
LL | struct Element(<Box<Box<Element>> as ParseTokens>::Output);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
note: required for `Box<Element>` to implement `ParseTokens`
--> $DIR/overflow.rs:12:31
|
LL | impl<T: ParseTokens + ?Sized> ParseTokens for Box<T> {
| - ^^^^^^^^^^^ ^^^^^^
| |
| unsatisfied trait bound introduced here
= note: 1 redundant requirement hidden
= note: required for `Box<Box<Element>>` to implement `ParseTokens`
error[E0275]: overflow evaluating the requirement `Box<Element>: ParseTokens`
--> $DIR/overflow.rs:18:22
|
LL | impl ParseTokens for Element {
| ^^^^^^^
|
note: required for `Box<Box<Element>>` to implement `ParseTokens`
--> $DIR/overflow.rs:12:31
|
LL | impl<T: ParseTokens + ?Sized> ParseTokens for Box<T> {
| ----------- ^^^^^^^^^^^ ^^^^^^
| |
| unsatisfied trait bound introduced here
note: required because it appears within the type `Element`
--> $DIR/overflow.rs:16:8
|
LL | struct Element(<Box<Box<Element>> as ParseTokens>::Output);
| ^^^^^^^
note: required by a bound in `ParseTokens`
--> $DIR/overflow.rs:9:1
|
LL | / trait ParseTokens {
LL | | type Output;
LL | | }
| |_^ required by this bound in `ParseTokens`
error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0275`.
tests/ui/sized-hierarchy/overflow.rs
+4 -2
View File
@@ -1,9 +1,13 @@
//@ compile-flags: --crate-type=lib
//@ revisions: current next
//@ ignore-compare-mode-next-solver (explicit revisions)
//@[current] check-pass
//@[next] check-pass
//@[next] compile-flags: -Znext-solver
// FIXME(sized_hierarchy): this is expected to fail in the old solver when there
// isn't a temporary revert of the `sized_hierarchy` feature
use std::marker::PhantomData;
trait ParseTokens {
@@ -14,8 +18,6 @@ impl<T: ParseTokens + ?Sized> ParseTokens for Box<T> {
}
struct Element(<Box<Box<Element>> as ParseTokens>::Output);
//[current]~^ ERROR overflow evaluating
impl ParseTokens for Element {
//[current]~^ ERROR overflow evaluating
type Output = ();
}
tests/ui/traits/resolve-impl-before-constrain-check.rs
-1
View File
@@ -15,7 +15,6 @@ fn call() {}
fn test() -> impl Sized {
<() as Callable>::call()
//~^ ERROR: type annotations needed
}
fn main() {}
tests/ui/traits/resolve-impl-before-constrain-check.stderr
+2 -9
View File
@@ -4,13 +4,6 @@ error[E0207]: the type parameter `V` is not constrained by the impl trait, self
LL | impl<V: ?Sized> Callable for () {
| ^ unconstrained type parameter
error[E0282]: type annotations needed
--> $DIR/resolve-impl-before-constrain-check.rs:17:6
|
LL | <() as Callable>::call()
| ^^ cannot infer type for type parameter `V`
error: aborting due to 1 previous error
error: aborting due to 2 previous errors
Some errors have detailed explanations: E0207, E0282.
For more information about an error, try `rustc --explain E0207`.
For more information about this error, try `rustc --explain E0207`.