From 25f14ae9b4c862a81f336355a1029e02cb7f8fe0 Mon Sep 17 00:00:00 2001
From: Mathias Schreck <schreck.mathias@googlemail.com>
Date: Sun, 19 Jul 2015 17:39:05 +0200
Subject: [PATCH] Fix: allow empty loop body in no-extra-semi (fixes #3075)

---
 lib/rules/no-extra-semi.js       | 11 +++++++++--
 tests/lib/rules/no-extra-semi.js | 10 ++++++++++
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/lib/rules/no-extra-semi.js b/lib/rules/no-extra-semi.js
index a3897ef22750..994fe2c2f0e8 100644
--- a/lib/rules/no-extra-semi.js
+++ b/lib/rules/no-extra-semi.js
@@ -40,11 +40,18 @@ module.exports = function(context) {
 
     return {
         /**
-         * Reports this empty statement.
+         * Reports this empty statement, except if the parent node is a loop.
          * @param {Node} node - A EmptyStatement node to be reported.
          * @returns {void}
          */
-        "EmptyStatement": report,
+        "EmptyStatement": function(node) {
+            var parent = node.parent,
+                allowedParentTypes = ["ForStatement", "ForInStatement", "ForOfStatement", "WhileStatement", "DoWhileStatement"];
+
+            if (allowedParentTypes.indexOf(parent.type) === -1) {
+                report(node);
+            }
+        },
 
         /**
          * Checks tokens from the head of this class body to the first MethodDefinition or the end of this class body.
diff --git a/tests/lib/rules/no-extra-semi.js b/tests/lib/rules/no-extra-semi.js
index 0342103a42dd..278b411f6933 100644
--- a/tests/lib/rules/no-extra-semi.js
+++ b/tests/lib/rules/no-extra-semi.js
@@ -21,6 +21,11 @@ eslintTester.addRuleTest("lib/rules/no-extra-semi", {
     valid: [
         "var x = 5;",
         "function foo(){}",
+        "for(;;);",
+        "while(0);",
+        "do;while(0);",
+        "for(a in b);",
+        { code: "for(a of b);", ecmaFeatures: { forOf: true } },
 
         // Class body.
         {code: "class A { }", ecmaFeatures: {classes: true}},
@@ -32,6 +37,11 @@ eslintTester.addRuleTest("lib/rules/no-extra-semi", {
     invalid: [
         { code: "var x = 5;;", errors: [{ message: "Unnecessary semicolon.", type: "EmptyStatement"}] },
         { code: "function foo(){};", errors: [{ message: "Unnecessary semicolon.", type: "EmptyStatement"}] },
+        { code: "for(;;);;", errors: [{ message: "Unnecessary semicolon.", type: "EmptyStatement" }] },
+        { code: "while(0);;", errors: [{ message: "Unnecessary semicolon.", type: "EmptyStatement" }] },
+        { code: "do;while(0);;", errors: [{ message: "Unnecessary semicolon.", type: "EmptyStatement" }] },
+        { code: "for(a in b);;", errors: [{ message: "Unnecessary semicolon.", type: "EmptyStatement" }] },
+        { code: "for(a of b);;", ecmaFeatures: { forOf: true }, errors: [{ message: "Unnecessary semicolon.", type: "EmptyStatement" }] },
 
         // Class body.
         {