Avoid manually instantiating some binders in error reporting with -Znext-solver

compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs

@@ -890,9 +890,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
         }
 
         if let Ok(Some(ImplSource::UserDefined(impl_data))) =
-            self.enter_forall(trait_ref, |trait_ref_for_select| {
-                SelectionContext::new(self).select(&obligation.with(self.tcx, trait_ref_for_select))
-            })
+            SelectionContext::new(self).poly_select(&obligation.with(self.tcx, trait_ref))
         {
             let impl_did = impl_data.impl_def_id;
             let trait_did = trait_ref.def_id();

compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs

@@ -6022,19 +6022,12 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
         {
             self.probe(|_| {
                 let ocx = ObligationCtxt::new(self);
-                self.enter_forall(pred, |pred| {
-                    let pred = ocx.normalize(
-                        &ObligationCause::dummy(),
-                        param_env,
-                        Unnormalized::new_wip(pred),
-                    );
-                    ocx.register_obligation(Obligation::new(
-                        self.tcx,
-                        ObligationCause::dummy(),
-                        param_env,
-                        pred,
-                    ));
-                });
+                ocx.register_obligation(Obligation::new(
+                    self.tcx,
+                    ObligationCause::dummy(),
+                    param_env,
+                    pred,
+                ));
                 if !ocx.try_evaluate_obligations().no_errors() {
                     // encountered errors.
                     return;

compiler/rustc_trait_selection/src/solve/select.rs

@@ -5,7 +5,7 @@ use rustc_infer::traits::solve::inspect::ProbeKind;
 use rustc_infer::traits::solve::{CandidateSource, Certainty, Goal};
 use rustc_infer::traits::{
     BuiltinImplSource, ImplSource, ImplSourceUserDefinedData, Obligation, ObligationCause,
-    Selection, SelectionError, SelectionResult, TraitObligation,
+    PolyTraitObligation, Selection, SelectionError, SelectionResult,
 };
 use rustc_macros::extension;
 use rustc_middle::{bug, span_bug};
@@ -16,10 +16,10 @@ use crate::solve::inspect::{self, InferCtxtProofTreeExt};
 
 #[extension(pub trait InferCtxtSelectExt<'tcx>)]
 impl<'tcx> InferCtxt<'tcx> {
-    /// Do not use this directly. This is called from [`crate::traits::SelectionContext::select`].
+    /// Do not use this directly. This is called from [`crate::traits::SelectionContext::poly_select`].
     fn select_in_new_trait_solver(
         &self,
-        obligation: &TraitObligation<'tcx>,
+        obligation: &PolyTraitObligation<'tcx>,
     ) -> SelectionResult<'tcx, Selection<'tcx>> {
         assert!(self.next_trait_solver());
 

compiler/rustc_trait_selection/src/traits/select/mod.rs

@@ -255,7 +255,9 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         &mut self,
         obligation: &PolyTraitObligation<'tcx>,
     ) -> SelectionResult<'tcx, Selection<'tcx>> {
-        assert!(!self.infcx.next_trait_solver());
+        if self.infcx.next_trait_solver() {
+            return self.infcx.select_in_new_trait_solver(obligation);
+        }
 
         let candidate = match self.select_from_obligation(obligation) {
             Err(SelectionError::Overflow(OverflowError::Canonical)) => {
@@ -292,10 +294,6 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         &mut self,
         obligation: &TraitObligation<'tcx>,
     ) -> SelectionResult<'tcx, Selection<'tcx>> {
-        if self.infcx.next_trait_solver() {
-            return self.infcx.select_in_new_trait_solver(obligation);
-        }
-
         self.poly_select(&Obligation {
             cause: obligation.cause.clone(),
             param_env: obligation.param_env,

tests/ui/higher-ranked/trait-bounds/normalize-under-binder/issue-62529-3.stderr

@@ -8,14 +8,6 @@ LL |         call(f, ());
    |
    = note: expected a closure with signature `for<'a> fn(<_ as ATC<'a>>::Type)`
               found a closure with signature `fn(())`
-note: this is a known limitation of the trait solver that will be lifted in the future
-  --> $DIR/issue-62529-3.rs:25:14
-   |
-LL |         call(f, ());
-   |         -----^-----
-   |         |    |
-   |         |    the trait solver is unable to infer the generic types that should be inferred from this argument
-   |         add turbofish arguments to this call to specify the types manually, even if it's redundant
 note: required by a bound in `call`
   --> $DIR/issue-62529-3.rs:9:36
    |

tests/ui/mismatched_types/closure-mismatch.next.stderr

@@ -9,14 +9,6 @@ LL |     baz(|_| ());
    = help: the trait `for<'a> FnOnce(&'a ())` is not implemented for closure `{closure@$DIR/closure-mismatch.rs:12:9: 12:12}`
    = note: expected a closure with signature `for<'a> fn(&'a ())`
               found a closure with signature `fn(&())`
-note: this is a known limitation of the trait solver that will be lifted in the future
-  --> $DIR/closure-mismatch.rs:12:9
-   |
-LL |     baz(|_| ());
-   |     ----^^^----
-   |     |   |
-   |     |   the trait solver is unable to infer the generic types that should be inferred from this argument
-   |     add turbofish arguments to this call to specify the types manually, even if it's redundant
 note: required for `{closure@$DIR/closure-mismatch.rs:12:9: 12:12}` to implement `Foo`
   --> $DIR/closure-mismatch.rs:7:18
    |
@@ -41,14 +33,6 @@ LL |     baz(|x| ());
    = help: the trait `for<'a> FnOnce(&'a ())` is not implemented for closure `{closure@$DIR/closure-mismatch.rs:16:9: 16:12}`
    = note: expected a closure with signature `for<'a> fn(&'a ())`
               found a closure with signature `fn(&())`
-note: this is a known limitation of the trait solver that will be lifted in the future
-  --> $DIR/closure-mismatch.rs:16:9
-   |
-LL |     baz(|x| ());
-   |     ----^^^----
-   |     |   |
-   |     |   the trait solver is unable to infer the generic types that should be inferred from this argument
-   |     add turbofish arguments to this call to specify the types manually, even if it's redundant
 note: required for `{closure@$DIR/closure-mismatch.rs:16:9: 16:12}` to implement `Foo`
   --> $DIR/closure-mismatch.rs:7:18
    |

tests/ui/traits/non_lifetime_binders/universe-error-host-effect.rs

@@ -0,0 +1,28 @@
+//@ compile-flags: -Znext-solver
+
+#![feature(const_trait_impl, non_lifetime_binders, sized_hierarchy)]
+#![allow(incomplete_features)]
+
+use std::marker::PointeeSized;
+
+const trait Other<U: PointeeSized, V: PointeeSized>: PointeeSized {}
+
+trait Guard {}
+
+const impl<X: PointeeSized> Other<X, i32> for X {}
+
+impl<X: PointeeSized> Other<u8, u32> for X where u8: Guard {}
+//~^ ERROR the trait bound `u8: Guard` is not satisfied
+
+fn foo<U: PointeeSized, V: PointeeSized>()
+where
+    for<T> T: const Other<U, V>,
+{
+}
+
+fn bar() {
+    foo::<_, _>();
+    //~^ ERROR the trait bound `u8: Guard` is not satisfied
+}
+
+fn main() {}

tests/ui/traits/non_lifetime_binders/universe-error-host-effect.stderr

@@ -0,0 +1,44 @@
+error[E0277]: the trait bound `u8: Guard` is not satisfied
+  --> $DIR/universe-error-host-effect.rs:14:50
+   |
+LL | impl<X: PointeeSized> Other<u8, u32> for X where u8: Guard {}
+   |                                                  ^^^^^^^^^ the trait `Guard` is not implemented for `u8`
+   |
+help: this trait has no implementations, consider adding one
+  --> $DIR/universe-error-host-effect.rs:10:1
+   |
+LL | trait Guard {}
+   | ^^^^^^^^^^^
+help: add `#![feature(trivial_bounds)]` to the crate attributes to enable
+   |
+LL + #![feature(trivial_bounds)]
+   |
+
+error[E0277]: the trait bound `u8: Guard` is not satisfied
+  --> $DIR/universe-error-host-effect.rs:24:11
+   |
+LL |     foo::<_, _>();
+   |           ^ the trait `Guard` is not implemented for `u8`
+   |
+help: this trait has no implementations, consider adding one
+  --> $DIR/universe-error-host-effect.rs:10:1
+   |
+LL | trait Guard {}
+   | ^^^^^^^^^^^
+note: required for `T` to implement `Other<u8, u32>`
+  --> $DIR/universe-error-host-effect.rs:14:23
+   |
+LL | impl<X: PointeeSized> Other<u8, u32> for X where u8: Guard {}
+   |                       ^^^^^^^^^^^^^^     ^           ----- unsatisfied trait bound introduced here
+note: required by a bound in `foo`
+  --> $DIR/universe-error-host-effect.rs:19:15
+   |
+LL | fn foo<U: PointeeSized, V: PointeeSized>()
+   |    --- required by a bound in this function
+LL | where
+LL |     for<T> T: const Other<U, V>,
+   |               ^^^^^^^^^^^^^^^^^ required by this bound in `foo`
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0277`.

tests/ui/traits/non_lifetime_binders/universe-error1.stderr → tests/ui/traits/non_lifetime_binders/universe-error1.current.stderr

@@ -1,11 +1,11 @@
 error[E0277]: the trait bound `T: Other<_>` is not satisfied
-  --> $DIR/universe-error1.rs:16:11
+  --> $DIR/universe-error1.rs:20:11
    |
 LL |     foo::<_>();
    |           ^ the trait `Other<_>` is not implemented for `T`
    |
 note: required by a bound in `foo`
-  --> $DIR/universe-error1.rs:13:15
+  --> $DIR/universe-error1.rs:17:15
    |
 LL | fn foo<U: PointeeSized>()
    |    --- required by a bound in this function

tests/ui/traits/non_lifetime_binders/universe-error1.next.stderr

@@ -0,0 +1,18 @@
+error[E0277]: the trait bound `T: Other<_>` is not satisfied
+  --> $DIR/universe-error1.rs:20:11
+   |
+LL |     foo::<_>();
+   |           ^ the trait `Other<_>` is not implemented for `T`
+   |
+note: required by a bound in `foo`
+  --> $DIR/universe-error1.rs:17:15
+   |
+LL | fn foo<U: PointeeSized>()
+   |    --- required by a bound in this function
+LL | where
+LL |     for<T> T: Other<U> {}
+   |               ^^^^^^^^ required by this bound in `foo`
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0277`.

tests/ui/traits/non_lifetime_binders/universe-error1.rs

@@ -1,3 +1,7 @@
+//@ revisions: current next
+//@ ignore-compare-mode-next-solver (explicit revisions)
+//@[next] compile-flags: -Znext-solver
+
 #![feature(sized_hierarchy)]
 #![feature(non_lifetime_binders)]