return newkey in rename

d2oracle/edit.go

@@ -1309,12 +1309,12 @@ func ensureNode(g *d2graph.Graph, excludedEdges []*d2ast.Edge, scopeObj *d2graph
 	}
 }
 
-func Rename(g *d2graph.Graph, key, newName string) (_ *d2graph.Graph, err error) {
+func Rename(g *d2graph.Graph, key, newName string) (_ *d2graph.Graph, newKey string, err error) {
 	defer xdefer.Errorf(&err, "failed to rename %#v to %#v", key, newName)
 
 	mk, err := d2parser.ParseMapKey(key)
 	if err != nil {
-		return nil, err
+		return nil, "", err
 	}
 
 	if len(mk.Edges) > 0 && mk.EdgeKey == nil {
@@ -1322,7 +1322,7 @@ func Rename(g *d2graph.Graph, key, newName string) (_ *d2graph.Graph, err error)
 		// Maybe we remove Rename and just have Move.
 		mk2, err := d2parser.ParseMapKey(newName)
 		if err != nil {
-			return nil, err
+			return nil, "", err
 		}
 
 		mk2.Key = mk.Key
@@ -1330,13 +1330,25 @@ func Rename(g *d2graph.Graph, key, newName string) (_ *d2graph.Graph, err error)
 	} else {
 		_, ok := d2graph.ReservedKeywords[newName]
 		if ok {
-			return nil, fmt.Errorf("cannot rename to reserved keyword: %#v", newName)
+			return nil, "", fmt.Errorf("cannot rename to reserved keyword: %#v", newName)
+		}
+		if mk.Key != nil {
+			obj, ok := g.Root.HasChild(d2graph.Key(mk.Key))
+			if !ok {
+				return nil, "", fmt.Errorf("key does not exist")
+			}
+			// If attempt to name something "x", but "x" already exists, rename it "x 2" instead
+			generatedName, _, err := generateUniqueKey(g, newName, obj, nil)
+			if err == nil {
+				newName = generatedName
+			}
 		}
 		// TODO: Handle mk.EdgeKey
 		mk.Key.Path[len(mk.Key.Path)-1] = d2ast.MakeValueBox(d2ast.RawString(newName, true)).StringBox()
 	}
 
-	return move(g, key, d2format.Format(mk), false)
+	g, err = move(g, key, d2format.Format(mk), false)
+	return g, newName, err
 }
 
 func trimReservedSuffix(path []*d2ast.StringBox) []*d2ast.StringBox {

d2oracle/edit_test.go

@@ -2193,7 +2193,7 @@ more.(ok.q.z -> p.k): "furbling, v.:"
 			key:     "1.2.3.4",
 			newName: "bic",
 
-			expErr: `failed to rename "1.2.3.4" to "bic": key referenced by from does not exist`,
+			expErr: `failed to rename "1.2.3.4" to "bic": key does not exist`,
 		},
 
 		{
@@ -2215,7 +2215,18 @@ more.(ok.q.z -> p.k): "furbling, v.:"
 			et := editTest{
 				text: tc.text,
 				testFunc: func(g *d2graph.Graph) (*d2graph.Graph, error) {
-					return d2oracle.Rename(g, tc.key, tc.newName)
+					objectsBefore := len(g.Objects)
+					var err error
+					g, _, err = d2oracle.Rename(g, tc.key, tc.newName)
+					if err == nil {
+						objectsAfter := len(g.Objects)
+						if objectsBefore != objectsAfter {
+							t.Log(d2format.Format(g.AST))
+							return nil, fmt.Errorf("rename cannot destroy or create objects: found %d objects before and %d objects after", objectsBefore, objectsAfter)
+						}
+					}
+
+					return g, err
 				},
 
 				exp:        tc.exp,

testdata/d2oracle/TestRename/errors/nonexistent.exp.json

@@ -1,4 +1,4 @@
 {
   "graph": null,
-  "err": "failed to rename \"1.2.3.4\" to \"bic\": key referenced by from does not exist"
+  "err": "failed to rename \"1.2.3.4\" to \"bic\": key does not exist"
 }