remove unused depends_on field and add test

The depends_on fields was deprecated during 0.12, and is no longer used.

Add a roundtrip test for the create_before_destroy status.

states/instance_object.go

@@ -42,11 +42,6 @@ type ResourceInstanceObject struct {
 	// destroy operations, we need to record the status to ensure a resource
 	// removed from the config will still be destroyed in the same manner.
 	CreateBeforeDestroy bool
-
-	// DependsOn corresponds to the deprecated `depends_on` field in the state.
-	// This field contained the configuration `depends_on` values, and some of
-	// the references from within a single module.
-	DependsOn []addrs.Referenceable
 }
 
 // ObjectStatus represents the status of a RemoteObject.

states/instance_object_src.go

@@ -55,8 +55,6 @@ type ResourceInstanceObjectSrc struct {
 	Status              ObjectStatus
 	Dependencies        []addrs.ConfigResource
 	CreateBeforeDestroy bool
-	// deprecated
-	DependsOn []addrs.Referenceable
 }
 
 // Decode unmarshals the raw representation of the object attributes. Pass the
@@ -89,7 +87,6 @@ func (os *ResourceInstanceObjectSrc) Decode(ty cty.Type) (*ResourceInstanceObjec
 		Value:               val,
 		Status:              os.Status,
 		Dependencies:        os.Dependencies,
-		DependsOn:           os.DependsOn,
 		Private:             os.Private,
 		CreateBeforeDestroy: os.CreateBeforeDestroy,
 	}, nil

states/state_deepcopy.go

@@ -158,12 +158,6 @@ func (obj *ResourceInstanceObjectSrc) DeepCopy() *ResourceInstanceObjectSrc {
 		copy(dependencies, obj.Dependencies)
 	}
 
-	var dependsOn []addrs.Referenceable
-	if obj.DependsOn != nil {
-		dependsOn = make([]addrs.Referenceable, len(obj.DependsOn))
-		copy(dependsOn, obj.DependsOn)
-	}
-
 	return &ResourceInstanceObjectSrc{
 		Status:              obj.Status,
 		SchemaVersion:       obj.SchemaVersion,
@@ -171,7 +165,6 @@ func (obj *ResourceInstanceObjectSrc) DeepCopy() *ResourceInstanceObjectSrc {
 		AttrsFlat:           attrsFlat,
 		AttrsJSON:           attrsJSON,
 		Dependencies:        dependencies,
-		DependsOn:           dependsOn,
 		CreateBeforeDestroy: obj.CreateBeforeDestroy,
 	}
 }

states/statefile/testdata/roundtrip/v4-cbd.in.tfstate

@@ -0,0 +1,34 @@
+{
+  "version": 4,
+  "serial": 0,
+  "lineage": "f2968801-fa14-41ab-a044-224f3a4adf04",
+  "terraform_version": "0.12.0",
+  "outputs": {
+    "numbers": {
+      "type": "string",
+      "value": "0,1"
+    }
+  },
+  "resources": [
+    {
+      "module": "module.modA",
+      "mode": "managed",
+      "type": "null_resource",
+      "name": "resource",
+      "provider": "provider[\"registry.terraform.io/-/null\"]",
+      "instances": [
+        {
+          "schema_version": 0,
+          "attributes": {
+            "id": "4639265839606265182",
+            "triggers": {
+              "input": "test"
+            }
+          },
+          "create_before_destroy": true,
+          "private": "bnVsbA=="
+        }
+      ]
+    }
+  ]
+}

states/statefile/testdata/roundtrip/v4-cbd.out.tfstate

@@ -0,0 +1 @@
+v4-cbd.in.tfstate

states/statefile/version3_upgrade.go

@@ -370,7 +370,6 @@ func upgradeInstanceObjectV3ToV4(rsOld *resourceStateV2, isOld *instanceStateV2,
 		Status:         status,
 		Deposed:        string(deposedKey),
 		AttributesFlat: attributes,
-		DependsOn:      dependencies,
 		SchemaVersion:  schemaVersion,
 		PrivateRaw:     privateJSON,
 	}, nil

states/statefile/version4.go

@@ -172,34 +172,6 @@ func prepareStateV4(sV4 *stateV4) (*File, tfdiags.Diagnostics) {
 				obj.Private = raw
 			}
 
-			{
-				// Allow both the deprecated `depends_on` and new
-				// `dependencies` to coexist for now so resources can be
-				// upgraded as they are refreshed.
-				depsRaw := isV4.DependsOn
-				deps := make([]addrs.Referenceable, 0, len(depsRaw))
-				for _, depRaw := range depsRaw {
-					ref, refDiags := addrs.ParseRefStr(depRaw)
-					diags = diags.Append(refDiags)
-					if refDiags.HasErrors() {
-						continue
-					}
-					if len(ref.Remaining) != 0 {
-						diags = diags.Append(tfdiags.Sourceless(
-							tfdiags.Error,
-							"Invalid resource instance metadata in state",
-							fmt.Sprintf("Instance %s declares dependency on %q, which is not a reference to a dependable object.", instAddr.Absolute(moduleAddr), depRaw),
-						))
-					}
-					if ref.Subject == nil {
-						// Should never happen
-						panic(fmt.Sprintf("parsing dependency %q for instance %s returned a nil address", depRaw, instAddr.Absolute(moduleAddr)))
-					}
-					deps = append(deps, ref.Subject)
-				}
-				obj.DependsOn = deps
-			}
-
 			{
 				depsRaw := isV4.Dependencies
 				deps := make([]addrs.ConfigResource, 0, len(depsRaw))
@@ -463,11 +435,6 @@ func appendInstanceObjectStateV4(rs *states.Resource, is *states.ResourceInstanc
 		deps[i] = depAddr.String()
 	}
 
-	depOn := make([]string, len(obj.DependsOn))
-	for i, depAddr := range obj.DependsOn {
-		depOn[i] = depAddr.String()
-	}
-
 	var rawKey interface{}
 	switch tk := key.(type) {
 	case addrs.IntKey:
@@ -493,7 +460,6 @@ func appendInstanceObjectStateV4(rs *states.Resource, is *states.ResourceInstanc
 		AttributesRaw:       obj.AttrsJSON,
 		PrivateRaw:          privateRaw,
 		Dependencies:        deps,
-		DependsOn:           depOn,
 		CreateBeforeDestroy: obj.CreateBeforeDestroy,
 	}), diags
 }
@@ -545,7 +511,6 @@ type instanceObjectStateV4 struct {
 	PrivateRaw []byte `json:"private,omitempty"`
 
 	Dependencies []string `json:"dependencies,omitempty"`
-	DependsOn    []string `json:"depends_on,omitempty"`
 
 	CreateBeforeDestroy bool `json:"create_before_destroy"`
 }