From de6f2902b53e7ddc19a021c9b85fa7bd7fd56630 Mon Sep 17 00:00:00 2001
From: Jacob Trueb <jtrueb@northwestern.edu>
Date: Sun, 29 Oct 2023 15:00:29 -0500
Subject: [PATCH] Prevent recursive AlreadyEncountered error formatting

---
 crates/polars-plan/src/logical_plan/mod.rs | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/crates/polars-plan/src/logical_plan/mod.rs b/crates/polars-plan/src/logical_plan/mod.rs
index d394327e41f43..045cd086ad792 100644
--- a/crates/polars-plan/src/logical_plan/mod.rs
+++ b/crates/polars-plan/src/logical_plan/mod.rs
@@ -79,7 +79,12 @@ impl std::fmt::Display for ErrorState {
         match self {
             ErrorState::NotYetEncountered { err } => write!(f, "NotYetEncountered({err})")?,
             ErrorState::AlreadyEncountered { prev_err_msg } => {
-                write!(f, "AlreadyEncountered({prev_err_msg})")?
+                if prev_err_msg.contains("AlreadyEncountered") {
+                    // Recurively formatting error messages leads to N! memory usage
+                    write!(f, "Multiple AlreadyEncountered")?
+                } else {
+                    write!(f, "AlreadyEncountered({prev_err_msg})")?
+                }
             },
         };