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Make WHERE_CLAUSES_OBJECT_SAFETY a regular object safety violation

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This commit is contained in:
Michael Goulet 2024-04-23 14:52:54 -04:00
parent 8768db9912
commit de6b219803
13 changed files with 75 additions and 192 deletions
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42
compiler/rustc_lint_defs/src/builtin.rs
View file

@ -136,7 +136,6 @@
USELESS_DEPRECATED,
WARNINGS,
WASM_C_ABI,
WHERE_CLAUSES_OBJECT_SAFETY,
WRITES_THROUGH_IMMUTABLE_POINTER,
// tidy-alphabetical-end
]
@ -2093,47 +2092,6 @@
"detects labels that are never used"
}
declare_lint! {
/// The `where_clauses_object_safety` lint detects for [object safety] of
/// [where clauses].
///
/// [object safety]: https://doc.rust-lang.org/reference/items/traits.html#object-safety
/// [where clauses]: https://doc.rust-lang.org/reference/items/generics.html#where-clauses
///
/// ### Example
///
/// ```rust,no_run
/// trait Trait {}
///
/// trait X { fn foo(&self) where Self: Trait; }
///
/// impl X for () { fn foo(&self) {} }
///
/// impl Trait for dyn X {}
///
/// // Segfault at opt-level 0, SIGILL otherwise.
/// pub fn main() { <dyn X as X>::foo(&()); }
/// ```
///
/// {{produces}}
///
/// ### Explanation
///
/// The compiler previously allowed these object-unsafe bounds, which was
/// incorrect. This is a [future-incompatible] lint to transition this to
/// a hard error in the future. See [issue #51443] for more details.
///
/// [issue #51443]: https://github.com/rust-lang/rust/issues/51443
/// [future-incompatible]: ../index.md#future-incompatible-lints
pub WHERE_CLAUSES_OBJECT_SAFETY,
Warn,
"checks the object safety of where clauses",
@future_incompatible = FutureIncompatibleInfo {
reason: FutureIncompatibilityReason::FutureReleaseErrorDontReportInDeps,
reference: "issue #51443 <https://github.com/rust-lang/rust/issues/51443>",
};
}
declare_lint! {
/// The `proc_macro_derive_resolution_fallback` lint detects proc macro
/// derives using inaccessible names from parent modules.

81
compiler/rustc_trait_selection/src/traits/object_safety.rs
View file

@ -13,7 +13,7 @@
use crate::infer::TyCtxtInferExt;
use crate::traits::query::evaluate_obligation::InferCtxtExt;
use crate::traits::{self, Obligation, ObligationCause};
use rustc_errors::{FatalError, MultiSpan};
use rustc_errors::FatalError;
use rustc_hir as hir;
use rustc_hir::def_id::DefId;
use rustc_middle::query::Providers;
@ -23,7 +23,6 @@
};
use rustc_middle::ty::{GenericArg, GenericArgs};
use rustc_middle::ty::{TypeVisitableExt, Upcast};
use rustc_session::lint::builtin::WHERE_CLAUSES_OBJECT_SAFETY;
use rustc_span::symbol::Symbol;
use rustc_span::Span;
use rustc_target::abi::Abi;
@ -66,44 +65,13 @@ fn object_safety_violations(tcx: TyCtxt<'_>, trait_def_id: DefId) -> &'_ [Object
}
fn check_is_object_safe(tcx: TyCtxt<'_>, trait_def_id: DefId) -> bool {
let violations = tcx.object_safety_violations(trait_def_id);
if violations.is_empty() {
return true;
}
// If the trait contains any other violations, then let the error reporting path
// report it instead of emitting a warning here.
if violations.iter().all(|violation| {
matches!(
violation,
ObjectSafetyViolation::Method(_, MethodViolationCode::WhereClauseReferencesSelf, _)
)
}) {
for violation in violations {
if let ObjectSafetyViolation::Method(
_,
MethodViolationCode::WhereClauseReferencesSelf,
span,
) = violation
{
lint_object_unsafe_trait(tcx, *span, trait_def_id, violation);
}
}
return true;
}
false
tcx.object_safety_violations(trait_def_id).is_empty()
}
/// We say a method is *vtable safe* if it can be invoked on a trait
/// object. Note that object-safe traits can have some
/// non-vtable-safe methods, so long as they require `Self: Sized` or
/// otherwise ensure that they cannot be used when `Self = Trait`.
///
/// [`MethodViolationCode::WhereClauseReferencesSelf`] is considered object safe due to backwards
/// compatibility, see <https://github.com/rust-lang/rust/issues/51443> and
/// [`WHERE_CLAUSES_OBJECT_SAFETY`].
pub fn is_vtable_safe_method(tcx: TyCtxt<'_>, trait_def_id: DefId, method: ty::AssocItem) -> bool {
debug_assert!(tcx.generics_of(trait_def_id).has_self);
debug!("is_vtable_safe_method({:?}, {:?})", trait_def_id, method);
@ -112,9 +80,7 @@ pub fn is_vtable_safe_method(tcx: TyCtxt<'_>, trait_def_id: DefId, method: ty::A
return false;
}
virtual_call_violations_for_method(tcx, trait_def_id, method)
.iter()
.all(|v| matches!(v, MethodViolationCode::WhereClauseReferencesSelf))
virtual_call_violations_for_method(tcx, trait_def_id, method).is_empty()
}
fn object_safety_violations_for_trait(
@ -163,47 +129,6 @@ fn object_safety_violations_for_trait(
violations
}
/// Lint object-unsafe trait.
fn lint_object_unsafe_trait(
tcx: TyCtxt<'_>,
span: Span,
trait_def_id: DefId,
violation: &ObjectSafetyViolation,
) {
// Using `CRATE_NODE_ID` is wrong, but it's hard to get a more precise id.
// It's also hard to get a use site span, so we use the method definition span.
tcx.node_span_lint(WHERE_CLAUSES_OBJECT_SAFETY, hir::CRATE_HIR_ID, span, |err| {
err.primary_message(format!(
"the trait `{}` cannot be made into an object",
tcx.def_path_str(trait_def_id)
));
let node = tcx.hir().get_if_local(trait_def_id);
let mut spans = MultiSpan::from_span(span);
if let Some(hir::Node::Item(item)) = node {
spans.push_span_label(item.ident.span, "this trait cannot be made into an object...");
spans.push_span_label(span, format!("...because {}", violation.error_msg()));
} else {
spans.push_span_label(
span,
format!(
"the trait cannot be made into an object because {}",
violation.error_msg()
),
);
};
err.span_note(
spans,
"for a trait to be \"object safe\" it needs to allow building a vtable to allow the \
call to be resolvable dynamically; for more information visit \
<https://doc.rust-lang.org/reference/items/traits.html#object-safety>",
);
if node.is_some() {
// Only provide the help if its a local trait, otherwise it's not
violation.solution().add_to(err);
}
});
}
fn sized_trait_bound_spans<'tcx>(
tcx: TyCtxt<'tcx>,
bounds: hir::GenericBounds<'tcx>,

19
src/tools/miri/tests/fail/issue-miri-2432.rs
View file

@ -1,19 +0,0 @@
#![allow(where_clauses_object_safety)]
trait Trait {}
trait X {
fn foo(&self)
where
Self: Trait;
}
impl X for () {
fn foo(&self) {}
}
impl Trait for dyn X {}
pub fn main() {
<dyn X as X>::foo(&()); //~ERROR: trying to call something that is not a method
}

15
src/tools/miri/tests/fail/issue-miri-2432.stderr
View file

@ -1,15 +0,0 @@
error: Undefined Behavior: `dyn` call trying to call something that is not a method
--> $DIR/issue-miri-2432.rs:LL:CC
|
LL | <dyn X as X>::foo(&());
| ^^^^^^^^^^^^^^^^^^^^^^ `dyn` call trying to call something that is not a method
|
= help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
= help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
= note: BACKTRACE:
= note: inside `main` at $DIR/issue-miri-2432.rs:LL:CC
note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
error: aborting due to 1 previous error

5
tests/ui/const-generics/generic_const_exprs/object-safety-err-where-bounds.rs
View file

@ -1,14 +1,11 @@
#![feature(generic_const_exprs)]
#![allow(incomplete_features)]
#![deny(where_clauses_object_safety)]
const fn bar<T: ?Sized>() -> usize { 7 }
trait Foo {
fn test(&self) where [u8; bar::<Self>()]: Sized;
//~^ ERROR the trait `Foo` cannot be made into an object
//~| WARN this was previously accepted by the compiler but is being phased out
}
impl Foo for () {
@ -16,7 +13,9 @@ impl Foo for () {
}
fn use_dyn(v: &dyn Foo) {
//~^ ERROR the trait `Foo` cannot be made into an object
v.test();
//~^ ERROR the trait `Foo` cannot be made into an object
}
fn main() {}

35
tests/ui/const-generics/generic_const_exprs/object-safety-err-where-bounds.stderr
View file

@ -1,24 +1,35 @@
error: the trait `Foo` cannot be made into an object
--> $DIR/object-safety-err-where-bounds.rs:9:8
error[E0038]: the trait `Foo` cannot be made into an object
--> $DIR/object-safety-err-where-bounds.rs:15:16
|
LL | fn test(&self) where [u8; bar::<Self>()]: Sized;
| ^^^^
LL | fn use_dyn(v: &dyn Foo) {
| ^^^^^^^ `Foo` cannot be made into an object
|
= warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
= note: for more information, see issue #51443 <https://github.com/rust-lang/rust/issues/51443>
note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
--> $DIR/object-safety-err-where-bounds.rs:9:8
--> $DIR/object-safety-err-where-bounds.rs:8:8
|
LL | trait Foo {
| --- this trait cannot be made into an object...
LL | fn test(&self) where [u8; bar::<Self>()]: Sized;
| ^^^^ ...because method `test` references the `Self` type in its `where` clause
= help: consider moving `test` to another trait
note: the lint level is defined here
--> $DIR/object-safety-err-where-bounds.rs:3:9
= help: only type `()` implements the trait, consider using it directly instead
error[E0038]: the trait `Foo` cannot be made into an object
--> $DIR/object-safety-err-where-bounds.rs:17:5
|
LL | #![deny(where_clauses_object_safety)]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^
LL | v.test();
| ^^^^^^^^ `Foo` cannot be made into an object
|
note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
--> $DIR/object-safety-err-where-bounds.rs:8:8
|
LL | trait Foo {
| --- this trait cannot be made into an object...
LL | fn test(&self) where [u8; bar::<Self>()]: Sized;
| ^^^^ ...because method `test` references the `Self` type in its `where` clause
= help: consider moving `test` to another trait
= help: only type `()` implements the trait, consider using it directly instead
error: aborting due to 1 previous error
error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0038`.

8
tests/ui/issues/issue-50781.rs
View file

@ -1,10 +1,7 @@
#![deny(where_clauses_object_safety)]
trait Trait {}
trait X {
fn foo(&self) where Self: Trait; //~ ERROR the trait `X` cannot be made into an object
//~^ WARN this was previously accepted by the compiler but is being phased out
fn foo(&self) where Self: Trait;
}
impl X for () {
@ -12,8 +9,11 @@ fn foo(&self) {}
}
impl Trait for dyn X {}
//~^ ERROR the trait `X` cannot be made into an object
pub fn main() {
// Check that this does not segfault.
<dyn X as X>::foo(&());
//~^ ERROR the trait `X` cannot be made into an object
//~| ERROR the trait `X` cannot be made into an object
}

52
tests/ui/issues/issue-50781.stderr
View file

@ -1,24 +1,52 @@
error: the trait `X` cannot be made into an object
--> $DIR/issue-50781.rs:6:8
error[E0038]: the trait `X` cannot be made into an object
--> $DIR/issue-50781.rs:11:16
|
LL | fn foo(&self) where Self: Trait;
| ^^^
LL | impl Trait for dyn X {}
| ^^^^^ `X` cannot be made into an object
|
= warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
= note: for more information, see issue #51443 <https://github.com/rust-lang/rust/issues/51443>
note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
--> $DIR/issue-50781.rs:6:8
--> $DIR/issue-50781.rs:4:8
|
LL | trait X {
| - this trait cannot be made into an object...
LL | fn foo(&self) where Self: Trait;
| ^^^ ...because method `foo` references the `Self` type in its `where` clause
= help: consider moving `foo` to another trait
note: the lint level is defined here
--> $DIR/issue-50781.rs:1:9
= help: only type `()` implements the trait, consider using it directly instead
error[E0038]: the trait `X` cannot be made into an object
--> $DIR/issue-50781.rs:16:23
|
LL | #![deny(where_clauses_object_safety)]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^
LL | <dyn X as X>::foo(&());
| ^^^ `X` cannot be made into an object
|
note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
--> $DIR/issue-50781.rs:4:8
|
LL | trait X {
| - this trait cannot be made into an object...
LL | fn foo(&self) where Self: Trait;
| ^^^ ...because method `foo` references the `Self` type in its `where` clause
= help: consider moving `foo` to another trait
= help: only type `()` implements the trait, consider using it directly instead
= note: required for the cast from `&()` to `&dyn X`
error: aborting due to 1 previous error
error[E0038]: the trait `X` cannot be made into an object
--> $DIR/issue-50781.rs:16:6
|
LL | <dyn X as X>::foo(&());
| ^^^^^ `X` cannot be made into an object
|
note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
--> $DIR/issue-50781.rs:4:8
|
LL | trait X {
| - this trait cannot be made into an object...
LL | fn foo(&self) where Self: Trait;
| ^^^ ...because method `foo` references the `Self` type in its `where` clause
= help: consider moving `foo` to another trait
= help: only type `()` implements the trait, consider using it directly instead
error: aborting due to 3 previous errors
For more information about this error, try `rustc --explain E0038`.

2
tests/ui/object-safety/issue-106247.rs
View file

@ -1,7 +1,5 @@
//@ check-pass
#![deny(where_clauses_object_safety)]
pub trait Trait {
fn method(&self) where Self: Sync;
}

1
tests/ui/traits/vtable/vtable-vacant.rs
View file

@ -1,7 +1,6 @@
//@ build-fail
#![feature(rustc_attrs)]
#![feature(negative_impls)]
#![allow(where_clauses_object_safety)]
// B --> A

2
tests/ui/traits/vtable/vtable-vacant.stderr
View file

@ -7,7 +7,7 @@ error: vtable entries for `<S as B>`: [
Method(<S as B>::foo_b1),
Vacant,
]
--> $DIR/vtable-vacant.rs:15:1
--> $DIR/vtable-vacant.rs:14:1
|
LL | trait B: A {
| ^^^^^^^^^^

1
tests/ui/where-clauses/self-in-where-clause-allowed.rs
View file

@ -1,7 +1,6 @@
//@ check-fail
#![feature(auto_traits)]
#![deny(where_clauses_object_safety)]
auto trait AutoTrait {}

4
tests/ui/where-clauses/self-in-where-clause-allowed.stderr
View file

@ -1,11 +1,11 @@
error[E0277]: the trait bound `dyn Trait: AutoTrait` is not satisfied
--> $DIR/self-in-where-clause-allowed.rs:22:18
--> $DIR/self-in-where-clause-allowed.rs:21:18
|
LL | trait_object.autotrait_bound();
| ^^^^^^^^^^^^^^^ the trait `AutoTrait` is not implemented for `dyn Trait`
|
note: required by a bound in `Trait::autotrait_bound`
--> $DIR/self-in-where-clause-allowed.rs:13:43
--> $DIR/self-in-where-clause-allowed.rs:12:43
|
LL | fn autotrait_bound(&self) where Self: AutoTrait {}
| ^^^^^^^^^ required by this bound in `Trait::autotrait_bound`