bail if there are too many non-region infer vars

rust-lang · Sep 20, 2024 · 5a219cb · 5a219cb
1 parent 2b11f26
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diff --git a/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/canonical.rs b/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/canonical.rs
@@ -157,6 +157,13 @@ where
             },
         );
 
+        let num_non_region_vars = canonical.variables.iter().filter(|c| !c.is_region()).count();
+        if num_non_region_vars > self.cx().recursion_limit() {
+            return Ok(self.make_ambiguous_response_no_constraints(MaybeCause::Overflow {
+                suggest_increasing_limit: true,
+            }));
+        }
+
         Ok(canonical)
     }
 

diff --git a/tests/ui/traits/coherence-alias-hang.rs b/tests/ui/traits/coherence-alias-hang.rs
@@ -1,4 +1,6 @@
 //@ check-pass
+//@ revisions: current next
+//[next]@ compile-flags: -Znext-solver
 
 // Regression test for nalgebra hang <https://github.com/rust-lang/rust/issues/130056>.