From 9a66433f72f673e4029656abfbad55c297d53617 Mon Sep 17 00:00:00 2001
From: Emil Ejbyfeldt <emil.ejbyfeldt@gmail.com>
Date: Wed, 9 Oct 2024 21:52:25 +0200
Subject: [PATCH] Fix panic on wrong number of arguments to substr

---
 datafusion/functions/src/unicode/substr.rs    | 7 +++++++
 datafusion/sqllogictest/test_files/errors.slt | 3 +++
 2 files changed, 10 insertions(+)

diff --git a/datafusion/functions/src/unicode/substr.rs b/datafusion/functions/src/unicode/substr.rs
index c253ef7e03e9..969969ef2f6f 100644
--- a/datafusion/functions/src/unicode/substr.rs
+++ b/datafusion/functions/src/unicode/substr.rs
@@ -84,6 +84,13 @@ impl ScalarUDFImpl for SubstrFunc {
     }
 
     fn coerce_types(&self, arg_types: &[DataType]) -> Result<Vec<DataType>> {
+        if arg_types.len() < 2 || arg_types.len() > 3 {
+            return plan_err!(
+                "The {} function requires 2 or 3 arguments, but got {}.",
+                self.name(),
+                arg_types.len()
+            );
+        }
         let first_data_type = match &arg_types[0] {
             DataType::Null => Ok(DataType::Utf8),
             DataType::LargeUtf8 | DataType::Utf8View | DataType::Utf8 => Ok(arg_types[0].clone()),
diff --git a/datafusion/sqllogictest/test_files/errors.slt b/datafusion/sqllogictest/test_files/errors.slt
index 7abf94932c71..ce0947525344 100644
--- a/datafusion/sqllogictest/test_files/errors.slt
+++ b/datafusion/sqllogictest/test_files/errors.slt
@@ -130,3 +130,6 @@ order by c9
 
 query error DataFusion error: Arrow error: Cast error: Cannot cast string 'foo' to value of Int64 type
 create table foo as values (1), ('foo');
+
+query error No function matches
+select 1 group by substr('');