From 2bfaddcf5776343957d08aa84747c685c82d31bc Mon Sep 17 00:00:00 2001
From: James Bardin <j.bardin@gmail.com>
Date: Fri, 24 Apr 2020 21:52:05 -0400
Subject: [PATCH] fix state mv to work without EachMode

The only situation where `state mv` needs to understand the each mode is
when with resource addresses that may reference a single instance, or a
group of for_each or count instances. In this case we can differentiate
the two by checking the existence of the NoKey instance key.
---
 command/state_mv.go      | 32 +++++++-------------------------
 command/state_mv_test.go | 24 +++++++++++++-----------
 2 files changed, 20 insertions(+), 36 deletions(-)

diff --git a/command/state_mv.go b/command/state_mv.go
index 7bcfb4428..10e9a86f7 100644
--- a/command/state_mv.go
+++ b/command/state_mv.go
@@ -279,10 +279,6 @@ func (c *StateMvCommand) Run(args []string) int {
 				ssFrom.ForgetResourceInstanceAll(addrFrom)
 				ssFrom.RemoveResourceIfEmpty(fromResourceAddr)
 
-				// since this is moving an instance, we can infer the target
-				// mode from the address.
-				toEachMode := eachModeForInstanceKey(addrTo.Resource.Key)
-
 				rs := stateTo.Resource(addrTo.ContainingResource())
 				if rs == nil {
 					// If we're moving to an address without an index then that
@@ -291,15 +287,13 @@ func (c *StateMvCommand) Run(args []string) int {
 					// address covers both). If there's an index in the
 					// target then allow creating the new instance here.
 					resourceAddr := addrTo.ContainingResource()
-					stateTo.SyncWrapper().SetResourceMeta(
+					stateTo.SyncWrapper().SetResourceProvider(
 						resourceAddr,
-						toEachMode,
 						fromProviderAddr, // in this case, we bring the provider along as if we were moving the whole resource
 					)
 					rs = stateTo.Resource(resourceAddr)
 				}
 
-				rs.EachMode = toEachMode
 				rs.Instances[addrTo.Resource.Key] = is
 			}
 		default:
@@ -372,20 +366,6 @@ func (c *StateMvCommand) Run(args []string) int {
 	return 0
 }
 
-func eachModeForInstanceKey(key addrs.InstanceKey) states.EachMode {
-	switch key.(type) {
-	case addrs.IntKey:
-		return states.EachList
-	case addrs.StringKey:
-		return states.EachMap
-	default:
-		if key == addrs.NoKey {
-			return states.NoEach
-		}
-		panic(fmt.Sprintf("don't know an each mode for instance key %#v", key))
-	}
-}
-
 // sourceObjectAddrs takes a single source object address and expands it to
 // potentially multiple objects that need to be handled within it.
 //
@@ -415,10 +395,12 @@ func (c *StateMvCommand) sourceObjectAddrs(state *states.State, matched addrs.Ta
 		//   terraform state mv aws_instance.foo aws_instance.bar[1]
 		// That wouldn't be allowed if aws_instance.foo had multiple instances
 		// since we can't move multiple instances into one.
-		if rs := state.Resource(addr); rs != nil && rs.EachMode == states.NoEach {
-			ret = append(ret, addr.Instance(addrs.NoKey))
-		} else {
-			ret = append(ret, addr)
+		if rs := state.Resource(addr); rs != nil {
+			if _, ok := rs.Instances[addrs.NoKey]; ok {
+				ret = append(ret, addr.Instance(addrs.NoKey))
+			} else {
+				ret = append(ret, addr)
+			}
 		}
 	default:
 		ret = append(ret, matched)
diff --git a/command/state_mv_test.go b/command/state_mv_test.go
index e84aca6f1..f970185b1 100644
--- a/command/state_mv_test.go
+++ b/command/state_mv_test.go
@@ -97,9 +97,10 @@ func TestStateMv(t *testing.T) {
 	if diags.HasErrors() {
 		t.Fatal(diags.Err())
 	}
-	i := s.Resource(addr)
-	if i.EachMode != states.EachList {
-		t.Fatalf("expected each mode List, got %s", i.EachMode)
+	for key := range s.Resource(addr).Instances {
+		if _, ok := key.(addrs.IntKey); !ok {
+			t.Fatalf("expected each mode List, got key %q", key)
+		}
 	}
 
 	// change from list to map
@@ -118,9 +119,10 @@ func TestStateMv(t *testing.T) {
 	if diags.HasErrors() {
 		t.Fatal(diags.Err())
 	}
-	i = s.Resource(addr)
-	if i.EachMode != states.EachMap {
-		t.Fatalf("expected each mode Map, got %s", i.EachMode)
+	for key := range s.Resource(addr).Instances {
+		if _, ok := key.(addrs.StringKey); !ok {
+			t.Fatalf("expected each mode map, found key %q", key)
+		}
 	}
 
 	// change from from map back to single
@@ -139,9 +141,10 @@ func TestStateMv(t *testing.T) {
 	if diags.HasErrors() {
 		t.Fatal(diags.Err())
 	}
-	i = s.Resource(addr)
-	if i.EachMode != states.NoEach {
-		t.Fatalf("expected each mode NoEach, got %s", i.EachMode)
+	for key := range s.Resource(addr).Instances {
+		if key != addrs.NoKey {
+			t.Fatalf("expected no each mode, found key %q", key)
+		}
 	}
 
 }
@@ -179,13 +182,12 @@ func TestStateMv_resourceToInstance(t *testing.T) {
 				Module:   addrs.RootModule,
 			},
 		)
-		s.SetResourceMeta(
+		s.SetResourceProvider(
 			addrs.Resource{
 				Mode: addrs.ManagedResourceMode,
 				Type: "test_instance",
 				Name: "bar",
 			}.Absolute(addrs.RootModuleInstance),
-			states.EachList,
 			addrs.AbsProviderConfig{
 				Provider: addrs.NewLegacyProvider("test"),
 				Module:   addrs.RootModule,