From 808e174dfc8e6921fa9aac71ae6e568e940687af Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Wed, 26 Jul 2023 01:35:51 +0000
Subject: [PATCH] Don't treat negative trait predicates as always knowable

---
 compiler/rustc_trait_selection/src/traits/select/mod.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/compiler/rustc_trait_selection/src/traits/select/mod.rs b/compiler/rustc_trait_selection/src/traits/select/mod.rs
index e086489b1bcb6..ca289ab6fe3f1 100644
--- a/compiler/rustc_trait_selection/src/traits/select/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/mod.rs
@@ -1487,7 +1487,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
     fn is_knowable<'o>(&mut self, stack: &TraitObligationStack<'o, 'tcx>) -> Result<(), Conflict> {
         debug!("is_knowable(intercrate={:?})", self.is_intercrate());
 
-        if !self.is_intercrate() || stack.obligation.polarity() == ty::ImplPolarity::Negative {
+        if !self.is_intercrate() {
             return Ok(());
         }