release notes for #1671

CHANGELOG.md

@@ -50,6 +50,29 @@
 
     This fix was contributed by [@eelco](https://github.com/eelco).
 
+* Fix an incorrect duplicate label error ([#1671](https://github.com/evanw/esbuild/pull/1671))
+
+    When labeling a statement in JavaScript, the label must be unique within the enclosing statements since the label determines the jump target of any labeled `break` or `continue` statement:
+
+    ```js
+    // This code is valid
+    x: y: z: break x;
+
+    // This code is invalid
+    x: y: x: break x;
+    ```
+
+    However, an enclosing label with the same name *is* allowed as long as it's located in a different function body. Since `break` and `continue` statements can't jump across function boundaries, the label is not ambiguous. This release fixes a bug where esbuild incorrectly treated this valid code as a syntax error:
+
+    ```js
+    // This code is valid, but was incorrectly considered a syntax error
+    x: (() => {
+      x: break x;
+    })();
+    ```
+
+    This fix was contributed by [@nevkontakte](https://github.com/nevkontakte).
+
 ## 0.13.4
 
 * Fix permission issues with the install script ([#1642](https://github.com/evanw/esbuild/issues/1642))

internal/js_parser/js_parser_test.go

@@ -1902,8 +1902,10 @@ func TestLabels(t *testing.T) {
 
 	expectPrinted(t, "x: y: z: 1", "x:\n  y:\n    z:\n      1;\n")
 	expectPrinted(t, "x: 1; y: 2; x: 3", "x:\n  1;\ny:\n  2;\nx:\n  3;\n")
+	expectPrinted(t, "x: (() => { x: 1; })()", "x:\n  (() => {\n    x:\n      1;\n  })();\n")
+	expectPrinted(t, "x: ({ f() { x: 1; } }).f()", "x:\n  ({ f() {\n    x:\n      1;\n  } }).f();\n")
+	expectPrinted(t, "x: (function() { x: 1; })()", "x:\n  (function() {\n    x:\n      1;\n  })();\n")
 	expectParseError(t, "x: y: x: 1", "<stdin>: error: Duplicate label \"x\"\n<stdin>: note: The original label \"x\" is here\n")
-	expectPrinted(t, "x: (function(){ x: 1; })()", "x:\n  (function() {\n    x:\n      1;\n  })();\n")
 }
 
 func TestArrow(t *testing.T) {