From 04b8da4e054df87a5c10cad7f52a69490da2508f Mon Sep 17 00:00:00 2001
From: grahamhar <grahamhar@users.noreply.github.com>
Date: Wed, 18 Nov 2020 19:04:27 +0000
Subject: [PATCH] Fix change detection

The change detection failed on maps, this introduces the use of go-cmp
which is better suited to this purpose.

Credit to https://github.com/gdavison for providing the tests.
---
 helper/schema/resource_data.go      |  3 +-
 helper/schema/resource_data_test.go | 78 +++++++++++++++++++++++++++++
 2 files changed, 80 insertions(+), 1 deletion(-)

diff --git a/helper/schema/resource_data.go b/helper/schema/resource_data.go
index d12e7546046..5519336c8a8 100644
--- a/helper/schema/resource_data.go
+++ b/helper/schema/resource_data.go
@@ -1,6 +1,7 @@
 package schema
 
 import (
+	"github.com/google/go-cmp/cmp"
 	"log"
 	"reflect"
 	"strings"
@@ -162,7 +163,7 @@ func (d *ResourceData) HasChange(key string) bool {
 		return !eq.Equal(n)
 	}
 
-	return !reflect.DeepEqual(o, n)
+	return !cmp.Equal(o, n)
 }
 
 // HasChangeExcept returns whether any keys outside the given key have been changed.
diff --git a/helper/schema/resource_data_test.go b/helper/schema/resource_data_test.go
index d3e06fa0ea6..c2c4d854e36 100644
--- a/helper/schema/resource_data_test.go
+++ b/helper/schema/resource_data_test.go
@@ -2073,6 +2073,84 @@ func TestResourceDataHasChange(t *testing.T) {
 
 			Key: "ports",
 
+			Change: false,
+		},
+		{
+			Schema: map[string]*Schema{
+				"vpc_config": {
+					Type:     TypeList,
+					Optional: true,
+					Elem: &Resource{
+						Schema: map[string]*Schema{
+							"subnet_ids": {
+								Type:     TypeSet,
+								Required: true,
+								Elem:     &Schema{Type: TypeString},
+								Set:      HashString,
+							},
+						},
+					},
+				},
+			},
+
+			State: &terraform.InstanceState{
+				Attributes: map[string]string{
+					"vpc_config.#":              "1",
+					"vpc_config.0.subnet_ids.#": "1",
+					fmt.Sprintf("vpc_config.0.subnet_ids.%d", HashString("abc-123")): "abc-123",
+				},
+			},
+
+			Diff: &terraform.InstanceDiff{
+				Attributes: map[string]*terraform.ResourceAttrDiff{
+					"vpc_config.0.subnet_ids.#": {
+						Old: "1",
+						New: "0",
+					},
+				},
+			},
+
+			Key: "vpc_config",
+
+			Change: true,
+		},
+		{
+			Schema: map[string]*Schema{
+				"vpc_config": {
+					Type:     TypeList,
+					Optional: true,
+					Elem: &Resource{
+						Schema: map[string]*Schema{
+							"subnet_ids": {
+								Type:     TypeSet,
+								Required: true,
+								Elem:     &Schema{Type: TypeString},
+								Set:      HashString,
+							},
+						},
+					},
+				},
+			},
+
+			State: &terraform.InstanceState{
+				Attributes: map[string]string{
+					"vpc_config.#":              "1",
+					"vpc_config.0.subnet_ids.#": "1",
+					fmt.Sprintf("vpc_config.0.subnet_ids.%d", HashString("abc-123")): "abc-123",
+				},
+			},
+
+			Diff: &terraform.InstanceDiff{
+				Attributes: map[string]*terraform.ResourceAttrDiff{
+					"tags.foo": {
+						Old: "",
+						New: "bar",
+					},
+				},
+			},
+
+			Key: "vpc_config",
+
 			Change: false,
 		},
 	}