From 55794eb6583608ecf15344f101d1e129ccffc3f4 Mon Sep 17 00:00:00 2001
From: Martin Atkins <mart@degeneration.co.uk>
Date: Fri, 31 May 2019 07:37:23 -0700
Subject: [PATCH] lang/funcs: Don't panic when distinct called with empty list

---
 lang/funcs/collection.go      | 3 +++
 lang/funcs/collection_test.go | 5 +++++
 2 files changed, 8 insertions(+)

diff --git a/lang/funcs/collection.go b/lang/funcs/collection.go
index 71b7a8466..1257895e3 100644
--- a/lang/funcs/collection.go
+++ b/lang/funcs/collection.go
@@ -363,6 +363,9 @@ var DistinctFunc = function.New(&function.Spec{
 			}
 		}
 
+		if len(list) == 0 {
+			return cty.ListValEmpty(retType.ElementType()), nil
+		}
 		return cty.ListVal(list), nil
 	},
 })
diff --git a/lang/funcs/collection_test.go b/lang/funcs/collection_test.go
index d1a543797..e408d385b 100644
--- a/lang/funcs/collection_test.go
+++ b/lang/funcs/collection_test.go
@@ -901,6 +901,11 @@ func TestDistinct(t *testing.T) {
 			}),
 			false,
 		},
+		{
+			cty.ListValEmpty(cty.String),
+			cty.ListValEmpty(cty.String),
+			false,
+		},
 		{
 			cty.ListVal([]cty.Value{
 				cty.StringVal("a"),