From 1712101b2a609156da53405bbf94b0ff7d011e36 Mon Sep 17 00:00:00 2001
From: James Bardin <j.bardin@gmail.com>
Date: Tue, 6 Jul 2021 19:08:27 -0400
Subject: [PATCH] function/stdlib: flatten no longer treats null values as
 unknown

---
 cty/function/stdlib/collection.go      |  2 +-
 cty/function/stdlib/collection_test.go | 33 ++++++++++++++++++++++++++
 2 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/cty/function/stdlib/collection.go b/cty/function/stdlib/collection.go
index f50f196e..279a20ee 100644
--- a/cty/function/stdlib/collection.go
+++ b/cty/function/stdlib/collection.go
@@ -538,7 +538,7 @@ func flattener(flattenList cty.Value) ([]cty.Value, []cty.ValueMarks, bool) {
 
 		// Any dynamic types could result in more collections that need to be
 		// flattened, so the type cannot be known.
-		if val.Type().Equals(cty.DynamicPseudoType) {
+		if val == cty.DynamicVal {
 			isKnown = false
 		}
 
diff --git a/cty/function/stdlib/collection_test.go b/cty/function/stdlib/collection_test.go
index cfafb4af..0d5d5e83 100644
--- a/cty/function/stdlib/collection_test.go
+++ b/cty/function/stdlib/collection_test.go
@@ -2031,6 +2031,39 @@ func TestFlatten(t *testing.T) {
 			}),
 			"",
 		},
+		{
+			cty.TupleVal([]cty.Value{
+				cty.TupleVal([]cty.Value{
+					cty.StringVal("a"),
+					cty.StringVal("b"),
+				}),
+				cty.NullVal(cty.DynamicPseudoType),
+				cty.TupleVal([]cty.Value{
+					cty.StringVal("c"),
+				}),
+			}),
+			cty.TupleVal([]cty.Value{
+				cty.StringVal("a"),
+				cty.StringVal("b"),
+				cty.NullVal(cty.DynamicPseudoType),
+				cty.StringVal("c"),
+			}),
+			"",
+		},
+		{
+			cty.TupleVal([]cty.Value{
+				cty.TupleVal([]cty.Value{
+					cty.StringVal("a"),
+					cty.StringVal("b"),
+				}),
+				cty.DynamicVal,
+				cty.TupleVal([]cty.Value{
+					cty.StringVal("c"),
+				}),
+			}),
+			cty.UnknownVal(cty.DynamicPseudoType),
+			"",
+		},
 	}
 
 	for _, test := range tests {