From 40174b634ac54e3f4926ede57e642a346740d780 Mon Sep 17 00:00:00 2001
From: James Bardin <j.bardin@gmail.com>
Date: Thu, 11 Nov 2021 10:15:29 -0500
Subject: [PATCH 1/2] ignore_changes changing a null map to empty

Fix an error where using `ignore_changes` would cause some null maps to
be saved as an empty map.
---
 internal/terraform/node_resource_abstract_instance.go | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/internal/terraform/node_resource_abstract_instance.go b/internal/terraform/node_resource_abstract_instance.go
index 3cab2b181a..b7b781191b 100644
--- a/internal/terraform/node_resource_abstract_instance.go
+++ b/internal/terraform/node_resource_abstract_instance.go
@@ -1289,10 +1289,15 @@ func processIgnoreChangesIndividual(prior, config cty.Value, ignoreChangesPath [
 		}
 
 		var newVal cty.Value
-		if len(configMap) == 0 {
-			newVal = cty.MapValEmpty(v.Type().ElementType())
-		} else {
+		switch {
+		case len(configMap) > 0:
 			newVal = cty.MapVal(configMap)
+		case v.IsNull():
+			// if the config value was null, and no values remain in the map,
+			// reset the value to null.
+			newVal = v
+		default:
+			newVal = cty.MapValEmpty(v.Type().ElementType())
 		}
 
 		if len(vMarks) > 0 {

From 9d19086c8eeef6b8ca5275f8d18d45033d81ed48 Mon Sep 17 00:00:00 2001
From: James Bardin <j.bardin@gmail.com>
Date: Thu, 11 Nov 2021 10:42:36 -0500
Subject: [PATCH 2/2] test for null map and fix lost map marks

Add a test to ensure ignore_changes does not change null maps to empty
maps.

Fix when a marked map revers the changes ignored within that map.
---
 .../node_resource_abstract_instance.go        |  2 +-
 internal/terraform/reduce_plan_test.go        | 48 +++++++++++++++++++
 2 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/internal/terraform/node_resource_abstract_instance.go b/internal/terraform/node_resource_abstract_instance.go
index b7b781191b..d2b6489be3 100644
--- a/internal/terraform/node_resource_abstract_instance.go
+++ b/internal/terraform/node_resource_abstract_instance.go
@@ -1301,7 +1301,7 @@ func processIgnoreChangesIndividual(prior, config cty.Value, ignoreChangesPath [
 		}
 
 		if len(vMarks) > 0 {
-			newVal = v.WithMarks(vMarks)
+			newVal = newVal.WithMarks(vMarks)
 		}
 
 		return newVal, nil
diff --git a/internal/terraform/reduce_plan_test.go b/internal/terraform/reduce_plan_test.go
index 2d134d2c28..f32101aaf5 100644
--- a/internal/terraform/reduce_plan_test.go
+++ b/internal/terraform/reduce_plan_test.go
@@ -369,6 +369,54 @@ func TestProcessIgnoreChangesIndividual(t *testing.T) {
 				"b": cty.StringVal("new b value"),
 			}),
 		},
+		"null_map": {
+			cty.ObjectVal(map[string]cty.Value{
+				"a": cty.StringVal("ok"),
+				"list": cty.ListVal([]cty.Value{
+					cty.ObjectVal(map[string]cty.Value{
+						"s":   cty.StringVal("ok"),
+						"map": cty.NullVal(cty.Map(cty.String)),
+					}),
+				}),
+			}),
+			cty.ObjectVal(map[string]cty.Value{
+				"a": cty.NullVal(cty.String),
+				"list": cty.ListVal([]cty.Value{
+					cty.ObjectVal(map[string]cty.Value{
+						"s":   cty.StringVal("ok"),
+						"map": cty.NullVal(cty.Map(cty.String)),
+					}),
+				}),
+			}),
+			[]string{"a"},
+			cty.ObjectVal(map[string]cty.Value{
+				"a": cty.StringVal("ok"),
+				"list": cty.ListVal([]cty.Value{
+					cty.ObjectVal(map[string]cty.Value{
+						"s":   cty.StringVal("ok"),
+						"map": cty.NullVal(cty.Map(cty.String)),
+					}),
+				}),
+			}),
+		},
+		"marked_map": {
+			cty.ObjectVal(map[string]cty.Value{
+				"map": cty.MapVal(map[string]cty.Value{
+					"key": cty.StringVal("val"),
+				}).Mark("marked"),
+			}),
+			cty.ObjectVal(map[string]cty.Value{
+				"map": cty.MapVal(map[string]cty.Value{
+					"key": cty.StringVal("new val"),
+				}).Mark("marked"),
+			}),
+			[]string{`map["key"]`},
+			cty.ObjectVal(map[string]cty.Value{
+				"map": cty.MapVal(map[string]cty.Value{
+					"key": cty.StringVal("val"),
+				}).Mark("marked"),
+			}),
+		},
 	}
 
 	for name, test := range tests {