feat: no-implicit-globals supports exported block comment (#16343)

* feat: support `"exported"` block comments

test: add valid tests

test: add invalid tests

* docs: mention about `exported` comment

docs: add correct example

* chore: use `variable.eslintExported` directly

* docs: add `:::` to close correct example

* fix: fix `exported` comment for multiple variables

* fix: add more invalid tests for global variable leaks

docs/src/rules/no-implicit-globals.md

@@ -5,6 +5,7 @@ rule_type: suggestion
 related_rules:
 - no-undef
 - no-global-assign
+- no-unused-vars
 further_reading:
 - https://benalman.com/news/2010/11/immediately-invoked-function-expression/
 - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Errors/Undeclared_var
@@ -255,6 +256,22 @@ window.MyGlobalFunction = (function() {
 
 :::
 
+### exported
+
+You can use `/* exported variableName */` block comments in the same way as in [`no-unused-vars`](./no-unused-vars). See the [`no-unused-vars` exported section](./no-unused-vars#exported) for details.
+
+Examples of **correct** code for `/* exported variableName */` operation:
+
+::: correct
+
+```js
+/* exported global_var */
+
+var global_var = 42;
+```
+
+:::
+
 ## When Not To Use It
 
 In the case of a browser script, if you want to be able to explicitly declare variables and functions in the global scope,

lib/linter/linter.js

@@ -213,6 +213,7 @@ function addDeclaredGlobals(globalScope, configGlobals, { exportedVariables, ena
 
         if (variable) {
             variable.eslintUsed = true;
+            variable.eslintExported = true;
         }
     });
 

lib/rules/no-implicit-globals.js

@@ -77,6 +77,11 @@ module.exports = {
                         return;
                     }
 
+                    // Variables exported by "exported" block comments
+                    if (variable.eslintExported) {
+                        return;
+                    }
+
                     variable.defs.forEach(def => {
                         const defNode = def.node;