fulfill: dedup newly added obligations

Author: lcnr

compiler/rustc_trait_selection/src/solve/fulfill.rs

@@ -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;
@@ -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;
@@ -57,6 +58,7 @@ pub struct FulfillmentCtxt<'tcx, E: 'tcx> {
 
 #[derive(Default, Debug)]
 struct ObligationStorage<'tcx> {
+    dedup: FxHashSet<(ty::ParamEnv<'tcx>, ty::Predicate<'tcx>)>,
     /// Obligations which resulted in an overflow in fulfillment itself.
     ///
     /// We cannot eagerly return these as error so we instead store them here
@@ -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)) {
+            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>>>,
@@ -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> {
@@ -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;
@@ -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),
                 }
             }
 

tests/ui/const-generics/issues/issue-88119.stderr

@@ -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
    |
@@ -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
    |
@@ -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`.

tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail-2.next.stderr

@@ -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`.

tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail-2.rs

@@ -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>() {

tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail.next.stderr

@@ -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`.

tests/ui/traits/const-traits/assoc-type-const-bound-usage-fail.rs

@@ -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>() {

tests/ui/traits/const-traits/trait-where-clause-const.rs

@@ -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>() {

tests/ui/traits/const-traits/trait-where-clause-const.stderr

@@ -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`.