Repository: eslint/eslint (js)

Issue:
no-undef misleading example
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**The version of ESLint you are using.**

master

**The problem you want to solve.**

From `no-undef` docs:

> Examples of **correct** code for this rule with `global` declaration:
>
> ```js
> /*global someFunction b:writable*/
> /*eslint no-undef: "error"*/
>
> var a = someFunction();
> b = 10;
> ```
>
> The `b:writable` syntax in `/*global */` indicates that assignment to `b` is correct.
>
> Examples of **incorrect** code for this rule with `global` declaration:
> 
> ```js
> /*global b*/
> /*eslint no-undef: "error"*/
> 
> b = 10;
> ```
> 
> By default, variables declared in `/*global */` are read-only, therefore assignment is incorrect.

'Incorrect' examples should be those with warnings, but ESLint does not report any warnings for the second example.

The problem with this is that the second example is actually **correct**, because `no-undef` rule does not check assignments to readonly global variables, that's what `no-global-assign` does.

**Your take on the correct solution to problem.**

I'm not sure. Probably modify the first example and remove the second. Maybe reference `no-global-assign`.  Perhaps also add more info to  `no-global-assign`. 

**Are you willing to submit a pull request to implement this change?**
Yes.

Pull request description:
Docs: Remove readonly/writable global logic from no-undef (fixes #11963)
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**What is the purpose of this pull request? (put an "X" next to item)**

[X] Documentation update #11963

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**What changes did you make? (Give an overview)**

Removed an example that does not apply to this rule.

Removed `writable` flag as it's irrelevant for this rule.

Modified a 'write' example (`b = 10`) to 'read' example (`var bar = a + 1`).

**Is there anything you'd like reviewers to focus on?**

Should there be a 'correct' example like this:

```js
/*global b*/
/*eslint no-undef: "error"*/
b = 10;
```

It is indeed a correct code for this rule, but it isn't the right way to use eslint global variables in general.



Patch:
diff --git a/README.md b/README.md
index ed485f66b..02c875ec6 100644
--- a/README.md
+++ b/README.md
@@ -260,7 +260,7 @@ The following companies, organizations, and individuals support ESLint's ongoing
 <h3>Gold Sponsors</h3>
 <p><a href="https://www.shopify.com"><img src="https://images.opencollective.com/shopify/eeb91aa/logo.png" alt="Shopify" height="96"></a> <a href="http://salesforce.com"><img src="https://images.opencollective.com/salesforce/853ecef/logo.png" alt="Salesforce" height="96"></a> <a href="https://badoo.com/team?utm_source=eslint"><img src="https://images.opencollective.com/badoo/2826a3b/logo.png" alt="Badoo" height="96"></a> <a href="https://www.airbnb.com/"><img src="https://images.opencollective.com/airbnb/001a341/logo.png" alt="Airbnb" height="96"></a> <a href="https://code.facebook.com/projects/"><img src="https://images.opencollective.com/fbopensource/fbb8a5b/logo.png" alt="Facebook Open Source" height="96"></a></p><h3>Silver Sponsors</h3>
 <p><a href="https://www.ampproject.org/"><img src="https://images.opencollective.com/amp/c8a3b25/logo.png" alt="AMP Project" height="64"></a></p><h3>Bronze Sponsors</h3>
-<p><a href="https://uxplanet.org/top-ui-ux-design-agencies-user-experience-firms-8c54697e290"><img src="https://images.opencollective.com/ux-top-5/cae5dfe/logo.png" alt="UX Top 5" height="32"></a> <a href="https://clay.global"><img src="https://images.opencollective.com/clayglobal/2468f34/logo.png" alt="clay" height="32"></a> <a href="https://discordapp.com"><img src="https://images.opencollective.com/discordapp/7e3d9a9/logo.png" alt="Discord" height="32"></a> <a href="https://themeisle.com"><img src="https://images.opencollective.com/themeisle/logo.png" alt="ThemeIsle" height="32"></a> <a href="https://tekhattan.com"><img src="https://images.opencollective.com/tekhattan/bc73c28/logo.png" alt="TekHattan" height="32"></a> <a href="https://www.marfeel.com/"><img src="https://images.opencollective.com/marfeel/4b88e30/logo.png" alt="Marfeel" height="32"></a> <a href="http://www.firesticktricks.com"><img src="https://images.opencollective.com/fire-stick-tricks/b8fbe2c/logo.png" alt="Fire Stick Tricks" height="32"></a> <a href="https://jsheroes.io/"><img src="https://images.opencollective.com/jsheroes1/9fedf0b/logo.png" alt="JSHeroes " height="32"></a> <a href="https://faithlife.com/ref/about"><img src="https://images.opencollective.com/faithlife/534b832/logo.png" alt="Faithlife" height="32"></a></p>
+<p><a href="https://icons8.com"><img src="https://images.opencollective.com/icons8/0b37d14/logo.png" alt="Free Icons by Icons8" height="32"></a> <a href="https://uxplanet.org/top-ui-ux-design-agencies-user-experience-firms-8c54697e290"><img src="https://images.opencollective.com/ui-ux-design-agencies/cae5dfe/logo.png" alt="UI UX Design Agencies" height="32"></a> <a href="https://clay.global"><img src="https://images.opencollective.com/clayglobal/2468f34/logo.png" alt="clay" height="32"></a> <a href="https://discordapp.com"><img src="https://images.opencollective.com/discordapp/7e3d9a9/logo.png" alt="Discord" height="32"></a> <a href="https://themeisle.com"><img src="https://images.opencollective.com/themeisle/logo.png" alt="ThemeIsle" height="32"></a> <a href="https://tekhattan.com"><img src="https://images.opencollective.com/tekhattan/bc73c28/logo.png" alt="TekHattan" height="32"></a> <a href="https://www.marfeel.com/"><img src="https://images.opencollective.com/marfeel/4b88e30/logo.png" alt="Marfeel" height="32"></a> <a href="http://www.firesticktricks.com"><img src="https://images.opencollective.com/fire-stick-tricks/b8fbe2c/logo.png" alt="Fire Stick Tricks" height="32"></a> <a href="https://jsheroes.io/"><img src="https://images.opencollective.com/jsheroes1/9fedf0b/logo.png" alt="JSHeroes " height="32"></a> <a href="https://faithlife.com/ref/about"><img src="https://images.opencollective.com/faithlife/534b832/logo.png" alt="Faithlife" height="32"></a></p>
 <!--sponsorsend-->
 
 ## <a name="technology-sponsors"></a>Technology Sponsors
diff --git a/docs/rules/no-undef.md b/docs/rules/no-undef.md
index f5dc5a280..faaf978cc 100644
--- a/docs/rules/no-undef.md
+++ b/docs/rules/no-undef.md
@@ -11,32 +11,25 @@ Examples of **incorrect** code for this rule:
 ```js
 /*eslint no-undef: "error"*/
 
-var a = someFunction();
-b = 10;
+var foo = someFunction();
+var bar = a + 1;
 ```
 
 Examples of **correct** code for this rule with `global` declaration:
 
 ```js
-/*global someFunction b:writable*/
+/*global someFunction, a*/
 /*eslint no-undef: "error"*/
 
-var a = someFunction();
-b = 10;
+var foo = someFunction();
+var bar = a + 1;
 ```
 
-The `b:writable` syntax in `/*global */` indicates that assignment to `b` is correct.
+Note that this rule does not disallow assignments to read-only global variables.
+See [no-global-assign](no-global-assign.md) if you also want to disallow those assignments.
 
-Examples of **incorrect** code for this rule with `global` declaration:
-
-```js
-/*global b*/
-/*eslint no-undef: "error"*/
-
-b = 10;
-```
-
-By default, variables declared in `/*global */` are read-only, therefore assignment is incorrect.
+This rule also does not disallow redeclarations of global variables.
+See [no-redeclare](no-redeclare.md) if you also want to disallow those redeclarations.
 
 ## Options
 
@@ -111,3 +104,8 @@ If explicit declaration of global variables is not to your taste.
 ## Compatibility
 
 This rule provides compatibility with treatment of global variables in [JSHint](http://jshint.com/) and [JSLint](http://www.jslint.com).
+
+## Related Rules
+
+* [no-global-assign](no-global-assign.md)
+* [no-redeclare](no-redeclare.md)
diff --git a/lib/rules/no-extra-parens.js b/lib/rules/no-extra-parens.js
index 6c3198b5f..c9278f2d0 100644
--- a/lib/rules/no-extra-parens.js
+++ b/lib/rules/no-extra-parens.js
@@ -686,6 +686,13 @@ module.exports = {
 
             CallExpression: checkCallNew,
 
+            ClassBody(node) {
+                node.body
+                    .filter(member => member.type === "MethodDefinition" && member.computed &&
+                        member.key && hasExcessParens(member.key) && precedence(member.key) >= PRECEDENCE_OF_ASSIGNMENT_EXPR)
+                    .forEach(member => report(member.key));
+            },
+
             ConditionalExpression(node) {
                 if (isReturnAssignException(node)) {
                     return;


Test patch:
diff --git a/tests/lib/rules/no-extra-parens.js b/tests/lib/rules/no-extra-parens.js
index 7be7d6e9e..6c6eeb2a1 100644
--- a/tests/lib/rules/no-extra-parens.js
+++ b/tests/lib/rules/no-extra-parens.js
@@ -160,6 +160,13 @@ ruleTester.run("no-extra-parens", rule, {
         "const {[a]:b=1} = {}",
         "const {[(a, b)]:c} = {}",
         "const {a, ...b} = {}",
+        "class foo {}",
+        "class foo { constructor(){} a(){} get b(){} set b(bar){} get c(){} set d(baz){} static e(){} }",
+        "class foo { [a](){} get [b](){} set [b](bar){} get [c](){} set [d](baz){} static [e](){} }",
+        "class foo { [(a,b)](){} }",
+        "class foo { a(){} [b](){} c(){} [(d,e)](){} }",
+        "class foo { [(a,b)](){} c(){} [d](){} e(){} }",
+        "const foo = class { constructor(){} a(){} get b(){} set b(bar){} get c(){} set d(baz){} static e(){} }",
 
         // ExpressionStatement restricted productions
         "({});",
@@ -553,6 +560,22 @@ ruleTester.run("no-extra-parens", rule, {
         invalid("const {a, b:c, [(d+e)]:f, [(g,h)]:i, [j]:k} = {}", "const {a, b:c, [d+e]:f, [(g,h)]:i, [j]:k} = {}", "BinaryExpression", 1),
         invalid("const {[a+(b*c)]:d} = {}", "const {[a+b*c]:d} = {}", "BinaryExpression", 1),
         invalid("const {[(a, (b+c))]:d} = {}", "const {[(a, b+c)]:d} = {}", "BinaryExpression", 1),
+        invalid("class foo { [(a)](){} }", "class foo { [a](){} }", "Identifier"),
+        invalid("class foo {*[(Symbol.iterator)]() {}}", "class foo {*[Symbol.iterator]() {}}", "MemberExpression"),
+        invalid("class foo { get [(a)](){} }", "class foo { get [a](){} }", "Identifier"),
+        invalid("class foo { set [(a)](bar){} }", "class foo { set [a](bar){} }", "Identifier"),
+        invalid("class foo { static [(a)](bar){} }", "class foo { static [a](bar){} }", "Identifier"),
+        invalid("class foo { [(a=b)](){} }", "class foo { [a=b](){} }", "AssignmentExpression"),
+        invalid("class foo { constructor (){} [(a+b)](){} }", "class foo { constructor (){} [a+b](){} }", "BinaryExpression"),
+        invalid("class foo { [(a+b)](){} constructor (){} }", "class foo { [a+b](){} constructor (){} }", "BinaryExpression"),
+        invalid("class foo { [(a+b)](){} c(){} }", "class foo { [a+b](){} c(){} }", "BinaryExpression"),
+        invalid("class foo { a(){} [(b+c)](){} d(){} }", "class foo { a(){} [b+c](){} d(){} }", "BinaryExpression"),
+        invalid("class foo { [(a+b)](){} [c](){} }", "class foo { [a+b](){} [c](){} }", "BinaryExpression"),
+        invalid("class foo { [a](){} [(b+c)](){} [d](){} }", "class foo { [a](){} [b+c](){} [d](){} }", "BinaryExpression"),
+        invalid("class foo { [(a+b)](){} [(c,d)](){} }", "class foo { [a+b](){} [(c,d)](){} }", "BinaryExpression"),
+        invalid("class foo { [(a,b)](){} [(c+d)](){} }", "class foo { [(a,b)](){} [c+d](){} }", "BinaryExpression"),
+        invalid("class foo { [a+(b*c)](){} }", "class foo { [a+b*c](){} }", "BinaryExpression"),
+        invalid("const foo = class { [(a)](){} }", "const foo = class { [a](){} }", "Identifier"),
         invalid(
             "var foo = (function*() { if ((yield foo())) { return; } }())",
             "var foo = (function*() { if (yield foo()) { return; } }())",