fix: throw early error for delete this?.#x

packages/babel-parser/src/parser/expression.js

@@ -502,7 +502,8 @@ export default class ExpressionParser extends LValParser {
         if (arg.type === "Identifier") {
           this.raise(node.start, Errors.StrictDelete);
         } else if (
-          arg.type === "MemberExpression" &&
+          (arg.type === "MemberExpression" ||
+            arg.type === "OptionalMemberExpression") &&
           arg.property.type === "PrivateName"
         ) {
           this.raise(node.start, Errors.DeletePrivateField);

packages/babel-parser/test/fixtures/experimental/class-private-properties/failure-delete-optional-private-property/input.js

@@ -0,0 +1,6 @@
+class Foo {
+  #x;
+  constructor() {
+    delete this?.#x;
+  }
+}

packages/babel-parser/test/fixtures/experimental/class-private-properties/failure-delete-optional-private-property/options.json

@@ -0,0 +1,3 @@
+{
+  "plugins": ["classPrivateProperties"]
+}

packages/babel-parser/test/fixtures/experimental/class-private-properties/failure-delete-optional-private-property/output.json

@@ -0,0 +1,99 @@
+{
+  "type": "File",
+  "start":0,"end":62,"loc":{"start":{"line":1,"column":0},"end":{"line":6,"column":1}},
+  "errors": [
+    "SyntaxError: Deleting a private field is not allowed (4:4)"
+  ],
+  "program": {
+    "type": "Program",
+    "start":0,"end":62,"loc":{"start":{"line":1,"column":0},"end":{"line":6,"column":1}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ClassDeclaration",
+        "start":0,"end":62,"loc":{"start":{"line":1,"column":0},"end":{"line":6,"column":1}},
+        "id": {
+          "type": "Identifier",
+          "start":6,"end":9,"loc":{"start":{"line":1,"column":6},"end":{"line":1,"column":9},"identifierName":"Foo"},
+          "name": "Foo"
+        },
+        "superClass": null,
+        "body": {
+          "type": "ClassBody",
+          "start":10,"end":62,"loc":{"start":{"line":1,"column":10},"end":{"line":6,"column":1}},
+          "body": [
+            {
+              "type": "ClassPrivateProperty",
+              "start":14,"end":17,"loc":{"start":{"line":2,"column":2},"end":{"line":2,"column":5}},
+              "static": false,
+              "key": {
+                "type": "PrivateName",
+                "start":14,"end":16,"loc":{"start":{"line":2,"column":2},"end":{"line":2,"column":4}},
+                "id": {
+                  "type": "Identifier",
+                  "start":15,"end":16,"loc":{"start":{"line":2,"column":3},"end":{"line":2,"column":4},"identifierName":"x"},
+                  "name": "x"
+                }
+              },
+              "value": null
+            },
+            {
+              "type": "ClassMethod",
+              "start":20,"end":60,"loc":{"start":{"line":3,"column":2},"end":{"line":5,"column":3}},
+              "static": false,
+              "key": {
+                "type": "Identifier",
+                "start":20,"end":31,"loc":{"start":{"line":3,"column":2},"end":{"line":3,"column":13},"identifierName":"constructor"},
+                "name": "constructor"
+              },
+              "computed": false,
+              "kind": "constructor",
+              "id": null,
+              "generator": false,
+              "async": false,
+              "params": [],
+              "body": {
+                "type": "BlockStatement",
+                "start":34,"end":60,"loc":{"start":{"line":3,"column":16},"end":{"line":5,"column":3}},
+                "body": [
+                  {
+                    "type": "ExpressionStatement",
+                    "start":40,"end":56,"loc":{"start":{"line":4,"column":4},"end":{"line":4,"column":20}},
+                    "expression": {
+                      "type": "UnaryExpression",
+                      "start":40,"end":55,"loc":{"start":{"line":4,"column":4},"end":{"line":4,"column":19}},
+                      "operator": "delete",
+                      "prefix": true,
+                      "argument": {
+                        "type": "OptionalMemberExpression",
+                        "start":47,"end":55,"loc":{"start":{"line":4,"column":11},"end":{"line":4,"column":19}},
+                        "object": {
+                          "type": "ThisExpression",
+                          "start":47,"end":51,"loc":{"start":{"line":4,"column":11},"end":{"line":4,"column":15}}
+                        },
+                        "property": {
+                          "type": "PrivateName",
+                          "start":53,"end":55,"loc":{"start":{"line":4,"column":17},"end":{"line":4,"column":19}},
+                          "id": {
+                            "type": "Identifier",
+                            "start":54,"end":55,"loc":{"start":{"line":4,"column":18},"end":{"line":4,"column":19},"identifierName":"x"},
+                            "name": "x"
+                          }
+                        },
+                        "computed": false,
+                        "optional": true
+                      }
+                    }
+                  }
+                ],
+                "directives": []
+              }
+            }
+          ]
+        }
+      }
+    ],
+    "directives": []
+  }
+}