Revert "Do not need to account for overflow in predicate_can_apply"

This reverts commit cbe9328018.

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

@@ -2544,10 +2544,7 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
             let obligation =
                 Obligation::new(self.tcx, ObligationCause::dummy(), param_env, cleaned_pred);
 
-            // We don't use `InferCtxt::predicate_may_hold` because that
+            self.predicate_may_hold(&obligation)
-            // will re-run predicates that overflow locally, which ends up
-            // taking a really long time to compute.
-            self.evaluate_obligation(&obligation).map_or(false, |eval| eval.may_apply())
         })
     }
 

src/test/ui/traits/predicate_can_apply-hang.rs

@@ -1,6 +0,0 @@
-fn f<B>(x: Vec<[[[B; 1]; 1]; 1]>) -> impl PartialEq<B> {
-    //~^ ERROR can't compare `Vec<[[[B; 1]; 1]; 1]>` with `B`
-    x
-}
-
-fn main() {}

src/test/ui/traits/predicate_can_apply-hang.stderr

@@ -1,21 +0,0 @@
-error[E0277]: can't compare `Vec<[[[B; 1]; 1]; 1]>` with `B`
-  --> $DIR/predicate_can_apply-hang.rs:1:38
-   |
-LL | fn f<B>(x: Vec<[[[B; 1]; 1]; 1]>) -> impl PartialEq<B> {
-   |                                      ^^^^^^^^^^^^^^^^^ no implementation for `Vec<[[[B; 1]; 1]; 1]> == B`
-LL |
-LL |     x
-   |     - return type was inferred to be `Vec<[[[B; 1]; 1]; 1]>` here
-   |
-   = help: the trait `PartialEq<B>` is not implemented for `Vec<[[[B; 1]; 1]; 1]>`
-   = help: the following other types implement trait `PartialEq<Rhs>`:
-             <Vec<T, A1> as PartialEq<Vec<U, A2>>>
-             <Vec<T, A> as PartialEq<&[U; N]>>
-             <Vec<T, A> as PartialEq<&[U]>>
-             <Vec<T, A> as PartialEq<&mut [U]>>
-             <Vec<T, A> as PartialEq<[U; N]>>
-             <Vec<T, A> as PartialEq<[U]>>
-
-error: aborting due to previous error
-
-For more information about this error, try `rustc --explain E0277`.