feat(es/compat): Verify private property access (#4465)

crates/swc/tests/errors/lints/check-private-property/1/output.swc-stderr

@@ -0,0 +1,11 @@
+  x Illegal access to private class property.
+    ,----
+ 18 | foo.#bar;
+    : ^^^^^^^^
+    `----
+
+  x Illegal access to private class property.
+    ,----
+ 19 | foo.#privateMethod();
+    : ^^^^^^^^^^^^^^^^^^
+    `----

crates/swc/tests/errors/lints/check-private-property/1/private.js

@@ -0,0 +1,21 @@
+class Foo {
+	#bar = 'i\'m a private field!';
+
+  #privateMethod() {
+    return 'i\'m a private method!';
+  }
+
+  foo() {
+    return this.#bar;
+  }
+
+  bar() {
+    return this.#privateMethod();
+  }
+}
+
+var f = new Foo();
+console.log(f.foo());
+console.log(f.bar());
+foo.#bar;
+foo.#privateMethod();

crates/swc/tests/fixture/issues-4xxx/4464/1/input/exec.js

@@ -0,0 +1,19 @@
+class Foo {
+        #bar = 'i\'m a private field!';
+
+  #privateMethod() {
+    return 'i\'m a private method!';
+  }
+
+  foo() {
+    return this.#bar;
+  }
+
+  bar() {
+    return this.#privateMethod();
+  }
+}
+
+var f = new Foo();
+console.log(f.foo());
+console.log(f.bar());

crates/swc/tests/fixture/issues-4xxx/4464/1/output/exec.js

@@ -0,0 +1,34 @@
+import * as swcHelpers from "@swc/helpers";
+var _bar = /*#__PURE__*/ new WeakMap(), _privateMethod = /*#__PURE__*/ new WeakSet();
+var Foo = /*#__PURE__*/ function() {
+    "use strict";
+    function Foo() {
+        swcHelpers.classCallCheck(this, Foo);
+        swcHelpers.classPrivateMethodInit(this, _privateMethod);
+        swcHelpers.classPrivateFieldInit(this, _bar, {
+            writable: true,
+            value: "i'm a private field!"
+        });
+    }
+    swcHelpers.createClass(Foo, [
+        {
+            key: "foo",
+            value: function foo() {
+                return swcHelpers.classPrivateFieldGet(this, _bar);
+            }
+        },
+        {
+            key: "bar",
+            value: function bar() {
+                return swcHelpers.classPrivateMethodGet(this, _privateMethod, privateMethod).call(this);
+            }
+        }
+    ]);
+    return Foo;
+}();
+function privateMethod() {
+    return "i'm a private method!";
+}
+var f = new Foo();
+console.log(f.foo());
+console.log(f.bar());

crates/swc_ecma_transforms_compat/src/es2022/private_in_object.rs

@@ -11,6 +11,7 @@ use swc_ecma_ast::*;
 use swc_ecma_transforms_base::pass::JsPass;
 use swc_ecma_utils::{
     default_constructor, ident::IdentLike, prepend, private_ident, quote_ident, ExprFactory, Id,
+    HANDLER,
 };
 use swc_ecma_visit::{
     as_folder, noop_visit_mut_type, noop_visit_type, Visit, VisitMut, VisitMutWith, VisitWith,
@@ -367,6 +368,15 @@ impl VisitMut for PrivateInObject {
                 });
             }
 
+            Expr::Member(MemberExpr {
+                span,
+                obj: _,
+                prop: MemberProp::PrivateName(PrivateName { .. }),
+            }) => {
+                let error = "Illegal access to private class property.";
+                HANDLER.with(|h| h.struct_span_err(*span, error).emit());
+            }
+
             _ => {}
         }
     }