From c7a21fe86c31360a75a6cc0e93ed61a448f65c29 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Le=C3=B3n=20Orell=20Valerian=20Liehr?= <me@fmease.dev>
Date: Fri, 6 Mar 2026 18:42:32 +0100
Subject: [PATCH] [crater only] Syntactically reject equality predicates

---
 compiler/rustc_parse/src/parser/generics.rs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/compiler/rustc_parse/src/parser/generics.rs b/compiler/rustc_parse/src/parser/generics.rs
index 8c02092fd6788..fde3373836032 100644
--- a/compiler/rustc_parse/src/parser/generics.rs
+++ b/compiler/rustc_parse/src/parser/generics.rs
@@ -595,6 +595,7 @@ impl<'a> Parser<'a> {
         // FIXME: We are just dropping the binders in lifetime_defs on the floor here.
         } else if self.eat(exp!(Eq)) || self.eat(exp!(EqEq)) {
             let rhs_ty = self.parse_ty()?;
+            self.dcx().span_err(ty.span.to(rhs_ty.span), "[[[ equality predicate ]]]");
             Ok(ast::WherePredicateKind::EqPredicate(ast::WhereEqPredicate { lhs_ty: ty, rhs_ty }))
         } else {
             self.maybe_recover_bounds_doubled_colon(&ty)?;