From a5083eb43e4916b8dcce877041fea630f4d1b2e2 Mon Sep 17 00:00:00 2001
From: Niko Matsakis <niko@alum.mit.edu>
Date: Tue, 15 Mar 2022 20:14:18 -0400
Subject: [PATCH] add a fast path

---
 chalk-recursive/src/solve.rs | 6 ++++++
 chalk-solve/src/solve.rs     | 2 +-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/chalk-recursive/src/solve.rs b/chalk-recursive/src/solve.rs
index a3212bafb09..47db7080ab3 100644
--- a/chalk-recursive/src/solve.rs
+++ b/chalk-recursive/src/solve.rs
@@ -179,6 +179,12 @@ trait SolveIterationHelpers<I: Interner>: SolveDatabase<I> {
             } else {
                 debug!("Error");
             }
+
+            if let Some((cur_solution, _)) = &cur_solution {
+                if cur_solution.is_trivial_and_always_true(self.interner()) {
+                    break;
+                }
+            }
         }
 
         if let Some((s, _)) = cur_solution {
diff --git a/chalk-solve/src/solve.rs b/chalk-solve/src/solve.rs
index 19389188650..0734fc53ea3 100644
--- a/chalk-solve/src/solve.rs
+++ b/chalk-solve/src/solve.rs
@@ -101,7 +101,7 @@ impl<I: Interner> Solution<I> {
         Solution::Ambig(guidance)
     }
 
-    fn is_trivial_and_always_true(&self, interner: I) -> bool {
+    pub fn is_trivial_and_always_true(&self, interner: I) -> bool {
         match self {
             Solution::Unique(constrained_subst) => {
                 constrained_subst.value.subst.is_identity_subst(interner)