fix #1424: always generate private method names

CHANGELOG.md

@@ -104,6 +104,55 @@
     console.log((init_esm_file(), esm_file_exports).test());
     ```
 
+* Fix a code generation bug for private methods ([#1424](https://github.com/evanw/esbuild/issues/1424))
+
+    This release fixes a bug where when private methods are transformed and the target environment is one that supports private methods (such as `esnext`), the member function name was uninitialized and took on the zero value by default. This resulted in the member function name becoming `__create` instead of the correct name since that's the name of the symbol at index 0. Now esbuild always generates a private method symbol even when private methods are supported, so this is no longer an issue:
+
+    ```js
+    // Original code
+    class Foo {
+      #a() { return 'a' }
+      #b() { return 'b' }
+      static c
+    }
+
+    // Old output
+    var _a, __create, _b, __create;
+    var Foo = class {
+      constructor() {
+        __privateAdd(this, _a);
+        __privateAdd(this, _b);
+      }
+    };
+    _a = new WeakSet();
+    __create = function() {
+      return "a";
+    };
+    _b = new WeakSet();
+    __create = function() {
+      return "b";
+    };
+    __publicField(Foo, "c");
+
+    // New output
+    var _a, a_fn, _b, b_fn;
+    var Foo = class {
+      constructor() {
+        __privateAdd(this, _a);
+        __privateAdd(this, _b);
+      }
+    };
+    _a = new WeakSet();
+    a_fn = function() {
+      return "a";
+    };
+    _b = new WeakSet();
+    b_fn = function() {
+      return "b";
+    };
+    __publicField(Foo, "c");
+    ```
+
 * The CLI now stops watch and serve mode when stdin is closed ([#1449](https://github.com/evanw/esbuild/pull/1449))
 
     To facilitate esbuild being called from the Erlang VM, esbuild's command-line interface will now exit when in `--watch` or `--serve` mode if stdin is closed. This change is necessary because the Erlang VM doesn't have an API for terminating a child process, so it instead closes stdin to indicate that the process is no longer needed.

internal/bundler/bundler_lower_test.go

@@ -1571,3 +1571,25 @@ func TestLowerTemplateObject(t *testing.T) {
 		},
 	})
 }
+
+// See https://github.com/evanw/esbuild/issues/1424 for more information
+func TestLowerPrivateClassFieldStaticIssue1424(t *testing.T) {
+	lower_suite.expectBundled(t, bundled{
+		files: map[string]string{
+			"/entry.js": `
+				class T {
+					#a() { return 'a'; }
+					#b() { return 'b'; }
+					static c;
+					d() { console.log(this.#a()); }
+				}
+				new T().d();
+			`,
+		},
+		entryPaths: []string{"/entry.js"},
+		options: config.Options{
+			Mode:          config.ModeBundle,
+			AbsOutputFile: "/out.js",
+		},
+	})
+}

internal/bundler/snapshots/snapshots_lower.txt

@@ -341,6 +341,31 @@ class Foo {
 _foo = new WeakMap();
 console.log(new Foo().bar === 123);
 
+================================================================================
+TestLowerPrivateClassFieldStaticIssue1424
+---------- /out.js ----------
+// entry.js
+var _a, a_fn, _b, b_fn;
+var T = class {
+  constructor() {
+    __privateAdd(this, _a);
+    __privateAdd(this, _b);
+  }
+  d() {
+    console.log(__privateMethod(this, _a, a_fn).call(this));
+  }
+};
+_a = new WeakSet();
+a_fn = function() {
+  return "a";
+};
+_b = new WeakSet();
+b_fn = function() {
+  return "b";
+};
+__publicField(T, "c");
+new T().d();
+
 ================================================================================
 TestLowerPrivateClassMethodOrder
 ---------- /out.js ----------

internal/js_parser/js_parser.go

@@ -2159,13 +2159,11 @@ func (p *parser) parseProperty(kind js_ast.PropertyKind, opts propertyOpts, erro
 				p.log.AddRangeError(&p.tracker, keyRange, fmt.Sprintf("Invalid method name %q", name))
 			}
 			private.Ref = p.declareSymbol(declare, key.Loc, name)
-			if p.options.unsupportedJSFeatures.Has(declare.Feature()) {
-				methodRef := p.newSymbol(js_ast.SymbolOther, name[1:]+suffix)
-				if kind == js_ast.PropertySet {
-					p.privateSetters[private.Ref] = methodRef
-				} else {
-					p.privateGetters[private.Ref] = methodRef
-				}
+			methodRef := p.newSymbol(js_ast.SymbolOther, name[1:]+suffix)
+			if kind == js_ast.PropertySet {
+				p.privateSetters[private.Ref] = methodRef
+			} else {
+				p.privateGetters[private.Ref] = methodRef
 			}
 		}