New: Add no-restricted-exports rule (fixes #10428)

docs/rules/no-restricted-exports.md

@@ -0,0 +1,106 @@
+# Disallow specified names in exports (no-restricted-exports)
+
+In a project, certain names may be disallowed from being used as exported names for various reasons.
+
+## Rule Details
+
+This rule disallows specified names from being used as exported names.
+
+## Options
+
+By default, this rule doesn't disallow any names. Only the names you specify in the configuration will be disallowed.
+
+This rule has an object option:
+
+* `"restrictedNamedExports"` is an array of strings, where each string is a name to be restricted.
+
+Examples of **incorrect** code for this rule:
+
+```js
+/*eslint no-restricted-exports: ["error", {
+    "restrictedNamedExports": ["foo", "bar", "Baz", "a", "b", "c", "d"]
+}]*/
+
+export const foo = 1;
+
+export function bar() {}
+
+export class Baz {}
+
+const a = {};
+export { a };
+
+function someFunction() {}
+export { someFunction as b };
+
+export { c } from 'some_module';
+
+export { something as d } from 'some_module';
+```
+
+Examples of **correct** code for this rule:
+
+```js
+/*eslint no-restricted-exports: ["error", {
+    "restrictedNamedExports": ["foo", "bar", "Baz", "a", "b", "c", "d"]
+}]*/
+
+export const quux = 1;
+
+export function myFunction() {}
+
+export class MyClass {}
+
+const a = {};
+export { a as myObject };
+
+function someFunction() {}
+export { someFunction };
+
+export { c as someName } from 'some_module';
+
+export { something } from 'some_module';
+```
+
+### Default exports
+
+By design, this rule doesn't disallow `export default` declarations. If you configure `"default"` as a restricted name, that restriction will apply only to named export declarations.
+
+Examples of additional **incorrect** code for this rule:
+
+```js
+/*eslint no-restricted-exports: ["error", { "restrictedNamedExports": ["default"] }]*/
+
+function foo() {}
+
+export { foo as default };
+```
+
+```js
+/*eslint no-restricted-exports: ["error", { "restrictedNamedExports": ["default"] }]*/
+
+export { default } from 'some_module';
+```
+
+Examples of additional **correct** code for this rule:
+
+```js
+/*eslint no-restricted-exports: ["error", { "restrictedNamedExports": ["default", "foo"] }]*/
+
+export default function foo() {}
+```
+
+## Known Limitations
+
+This rule doesn't inspect the content of source modules in re-export declarations. In particular, if you are re-exporting everything from another module's export, that export may include a restricted name. This rule cannot detect such cases.
+
+```js
+
+//----- some_module.js -----
+export function foo() {}
+
+//----- my_module.js -----
+/*eslint no-restricted-exports: ["error", { "restrictedNamedExports": ["foo"] }]*/
+
+export * from 'some_module'; // allowed, although this declaration exports "foo" from my_module
+```

lib/rules/index.js

@@ -175,6 +175,7 @@ module.exports = new LazyLoadingRuleMap(Object.entries({
     "no-prototype-builtins": () => require("./no-prototype-builtins"),
     "no-redeclare": () => require("./no-redeclare"),
     "no-regex-spaces": () => require("./no-regex-spaces"),
+    "no-restricted-exports": () => require("./no-restricted-exports"),
     "no-restricted-globals": () => require("./no-restricted-globals"),
     "no-restricted-imports": () => require("./no-restricted-imports"),
     "no-restricted-modules": () => require("./no-restricted-modules"),

lib/rules/no-restricted-exports.js

@@ -0,0 +1,84 @@
+/**
+ * @fileoverview Rule to disallow specified names in exports
+ * @author Milos Djermanovic
+ */
+
+"use strict";
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+module.exports = {
+    meta: {
+        type: "suggestion",
+
+        docs: {
+            description: "disallow specified names in exports",
+            category: "ECMAScript 6",
+            recommended: false,
+            url: "https://eslint.org/docs/rules/no-restricted-exports"
+        },
+
+        schema: [{
+            type: "object",
+            properties: {
+                restrictedNamedExports: {
+                    type: "array",
+                    items: {
+                        type: "string"
+                    },
+                    uniqueItems: true
+                }
+            },
+            additionalProperties: false
+        }],
+
+        messages: {
+            restrictedNamed: "'{{name}}' is restricted from being used as an exported name."
+        }
+    },
+
+    create(context) {
+
+        const restrictedNames = new Set(context.options[0] && context.options[0].restrictedNamedExports);
+
+        /**
+         * Checks and reports given exported identifier.
+         * @param {ASTNode} node exported `Identifer` node to check.
+         * @returns {void}
+         */
+        function checkExportedName(node) {
+            const name = node.name;
+
+            if (restrictedNames.has(name)) {
+                context.report({
+                    node,
+                    messageId: "restrictedNamed",
+                    data: { name }
+                });
+            }
+        }
+
+        return {
+            ExportNamedDeclaration(node) {
+                const declaration = node.declaration;
+
+                if (declaration) {
+                    if (declaration.type === "FunctionDeclaration" || declaration.type === "ClassDeclaration") {
+                        checkExportedName(declaration.id);
+                    } else if (declaration.type === "VariableDeclaration") {
+                        context.getDeclaredVariables(declaration)
+                            .map(v => v.defs.find(d => d.parent === declaration))
+                            .map(d => d.name) // Identifier nodes
+                            .forEach(checkExportedName);
+                    }
+                } else {
+                    node.specifiers
+                        .map(s => s.exported)
+                        .forEach(checkExportedName);
+                }
+            }
+        };
+    }
+};