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fulfill: dedup newly added obligations #145714

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19 changes: 14 additions & 5 deletions compiler/rustc_trait_selection/src/solve/fulfill.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@ use std::marker::PhantomData;
use std::mem;
use std::ops::ControlFlow;

use rustc_data_structures::fx::FxHashSet;
use rustc_data_structures::thinvec::ExtractIf;
use rustc_hir::def_id::LocalDefId;
use rustc_infer::infer::InferCtxt;
Expand All @@ -19,7 +20,7 @@ use rustc_next_trait_solver::solve::{
};
use rustc_span::Span;
use thin_vec::ThinVec;
use tracing::instrument;
use tracing::{debug, instrument};

use self::derive_errors::*;
use super::Certainty;
Expand Down Expand Up @@ -57,6 +58,7 @@ pub struct FulfillmentCtxt<'tcx, E: 'tcx> {

#[derive(Default, Debug)]
struct ObligationStorage<'tcx> {
dedup: FxHashSet<(ty::ParamEnv<'tcx>, ty::Predicate<'tcx>)>,
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What happens if ?0: Tr and ?1: Tr both get constrained to i32: Tr? Do we not dedup in that case?

/// Obligations which resulted in an overflow in fulfillment itself.
///
/// We cannot eagerly return these as error so we instead store them here
Expand All @@ -67,7 +69,14 @@ struct ObligationStorage<'tcx> {
}

impl<'tcx> ObligationStorage<'tcx> {
fn register(
fn register(&mut self, obligation: PredicateObligation<'tcx>) {
if self.dedup.insert((obligation.param_env, obligation.predicate)) {
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@BoxyUwU BoxyUwU Sep 16, 2025 •
edited
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this dedups stuff with different recursion depths which seems wrong. in general this makes me nervous that we'll have a sort of "cache" that doesnt take into account all the inputs. Why not FxHashSet<PredicateObligation<'tcx>> which is the exact type used for the list of obligations to prove? Is it just because of the cause?

self.pending.push((obligation, None));
} else {
debug!("skipping already registered obligation: {obligation:?}");
}
}
fn readd_pending(
&mut self,
obligation: PredicateObligation<'tcx>,
stalled_on: Option<GoalStalledOn<TyCtxt<'tcx>>>,
Expand Down Expand Up @@ -161,7 +170,7 @@ where
obligation: PredicateObligation<'tcx>,
) {
assert_eq!(self.usable_in_snapshot, infcx.num_open_snapshots());
self.obligations.register(obligation, None);
self.obligations.register(obligation);
}

fn collect_remaining_errors(&mut self, infcx: &InferCtxt<'tcx>) -> Vec<E> {
Expand Down Expand Up @@ -205,7 +214,7 @@ where
// Only goals proven via the trait solver should be region dependent.
Certainty::Yes => {}
Certainty::Maybe(_) => {
self.obligations.register(obligation, None);
self.obligations.readd_pending(obligation, None);
}
}
continue;
Expand Down Expand Up @@ -256,7 +265,7 @@ where
infcx.push_hir_typeck_potentially_region_dependent_goal(obligation);
}
}
Certainty::Maybe(_) => self.obligations.register(obligation, stalled_on),
Certainty::Maybe(_) => self.obligations.readd_pending(obligation, stalled_on),
}
}

Expand Down
26 changes: 1 addition & 25 deletions tests/ui/const-generics/issues/issue-88119.stderr
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Expand Up @@ -30,18 +30,6 @@ note: required by a bound in `<&T as ConstName>`
LL | [(); name_len::<T>()]:,
| ^^^^^^^^^^^^^^^^^^^^^ required by this bound in `<&T as ConstName>`

error[E0275]: overflow evaluating the requirement `[(); name_len::<T>()] well-formed`
--> $DIR/issue-88119.rs:21:10
|
LL | [(); name_len::<T>()]:,
| ^^^^^^^^^^^^^^^
|
note: required by a bound in `<&T as ConstName>`
--> $DIR/issue-88119.rs:21:5
|
LL | [(); name_len::<T>()]:,
| ^^^^^^^^^^^^^^^^^^^^^ required by this bound in `<&T as ConstName>`

error[E0275]: overflow evaluating the requirement `&mut T: [const] ConstName`
--> $DIR/issue-88119.rs:26:49
|
Expand All @@ -66,18 +54,6 @@ note: required by a bound in `<&mut T as ConstName>`
LL | [(); name_len::<T>()]:,
| ^^^^^^^^^^^^^^^^^^^^^ required by this bound in `<&mut T as ConstName>`

error[E0275]: overflow evaluating the requirement `[(); name_len::<T>()] well-formed`
--> $DIR/issue-88119.rs:28:10
|
LL | [(); name_len::<T>()]:,
| ^^^^^^^^^^^^^^^
|
note: required by a bound in `<&mut T as ConstName>`
--> $DIR/issue-88119.rs:28:5
|
LL | [(); name_len::<T>()]:,
| ^^^^^^^^^^^^^^^^^^^^^ required by this bound in `<&mut T as ConstName>`

error[E0275]: overflow evaluating the requirement `&&mut u8: ConstName`
--> $DIR/issue-88119.rs:33:35
|
Expand All @@ -90,6 +66,6 @@ error[E0275]: overflow evaluating the requirement `&mut &u8: ConstName`
LL | pub const ICE_2: &'static [u8] = <&mut &u8 as ConstName>::NAME_BYTES;
| ^^^^^^^^

error: aborting due to 11 previous errors
error: aborting due to 9 previous errors

For more information about this error, try `rustc --explain E0275`.
8 changes: 1 addition & 7 deletions tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail-2.next.stderr
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Expand Up @@ -4,12 +4,6 @@ error[E0277]: the trait bound `U: [const] Other` is not satisfied
LL | T::Assoc::<U>::func();
| ^^^^^^^^^^^^^

error[E0277]: the trait bound `U: [const] Other` is not satisfied
--> $DIR/assoc-type-const-bound-usage-fail-2.rs:26:5
|
LL | <T as Trait>::Assoc::<U>::func();
| ^^^^^^^^^^^^^^^^^^^^^^^^

error: aborting due to 2 previous errors
error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0277`.
2 changes: 1 addition & 1 deletion tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail-2.rs
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Expand Up @@ -24,7 +24,7 @@ const fn fails<T: [const] Trait, U: Other>() {
T::Assoc::<U>::func();
//~^ ERROR the trait bound `U: [const] Other` is not satisfied
<T as Trait>::Assoc::<U>::func();
//~^ ERROR the trait bound `U: [const] Other` is not satisfied
//[current]~^ ERROR the trait bound `U: [const] Other` is not satisfied
}

const fn works<T: [const] Trait, U: [const] Other>() {
Expand Down
8 changes: 1 addition & 7 deletions tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail.next.stderr
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Expand Up @@ -4,12 +4,6 @@ error[E0277]: the trait bound `T: [const] Trait` is not satisfied
LL | T::Assoc::func();
| ^^^^^^^^

error[E0277]: the trait bound `T: [const] Trait` is not satisfied
--> $DIR/assoc-type-const-bound-usage-fail.rs:19:5
|
LL | <T as Trait>::Assoc::func();
| ^^^^^^^^^^^^^^^^^^^

error: aborting due to 2 previous errors
error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0277`.
2 changes: 1 addition & 1 deletion tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail.rs
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Expand Up @@ -17,7 +17,7 @@ const fn unqualified<T: Trait>() {
T::Assoc::func();
//~^ ERROR the trait bound `T: [const] Trait` is not satisfied
<T as Trait>::Assoc::func();
//~^ ERROR the trait bound `T: [const] Trait` is not satisfied
//[current]~^ ERROR the trait bound `T: [const] Trait` is not satisfied
}

const fn works<T: [const] Trait>() {
Expand Down
1 change: 0 additions & 1 deletion tests/ui/traits/const-traits/trait-where-clause-const.rs
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Expand Up @@ -21,7 +21,6 @@ const fn test1<T: [const] Foo + Bar>() {
T::b();
//~^ ERROR the trait bound
T::c::<T>();
//~^ ERROR the trait bound
}

const fn test2<T: [const] Foo + [const] Bar>() {
Expand Down
14 changes: 1 addition & 13 deletions tests/ui/traits/const-traits/trait-where-clause-const.stderr
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Expand Up @@ -10,18 +10,6 @@ note: required by a bound in `Foo::b`
LL | fn b() where Self: [const] Bar;
| ^^^^^^^^^^^ required by this bound in `Foo::b`

error[E0277]: the trait bound `T: [const] Bar` is not satisfied
--> $DIR/trait-where-clause-const.rs:23:12
|
LL | T::c::<T>();
| ^
|
note: required by a bound in `Foo::c`
--> $DIR/trait-where-clause-const.rs:16:13
|
LL | fn c<T: [const] Bar>();
| ^^^^^^^^^^^ required by this bound in `Foo::c`

error: aborting due to 2 previous errors
error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0277`.
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