[eslint] add rule to prevent export* in plugin index files (#109357)

* [eslint] add rule to prevent export* in plugin index files

* deduplicate export names for types/instances with the same name

* attempt to auto-fix duplicate exports too

* capture exported enums too

* enforce no_export_all for core too

* disable rule by default, allow opting-in for help fixing

* update tests

* reduce yarn.lock duplication

* add rule but no fixes

* disable all existing violations

* update api docs with new line numbers

* revert unnecessary changes to yarn.lock which only had drawbacks

* remove unnecessary eslint-disable

* rework codegen to split type exports and use babel to generate valid code

* check for "export types" deeply

* improve test by using fixtures

* add comments to some helper functions

* disable fix for namespace exports including types

* label all eslint-disable comments with related team-specific issue

* ensure that child exports of `export type` are always tracked as types

Co-authored-by: spalger <[email protected]>
Co-authored-by: Kibana Machine <[email protected]>

.eslintrc.js

@@ -1656,5 +1656,24 @@ module.exports = {
         '@typescript-eslint/prefer-ts-expect-error': 'error',
       },
     },
+
+    /**
+     * Disallow `export *` syntax in plugin/core public/server/common index files and instead
+     * require that plugins/core explicitly export the APIs that should be accessible outside the plugin.
+     *
+     * To add your plugin to this list just update the relevant glob with the name of your plugin
+     */
+    {
+      files: [
+        'src/core/{server,public,common}/index.ts',
+        'src/plugins/*/{server,public,common}/index.ts',
+        'src/plugins/*/*/{server,public,common}/index.ts',
+        'x-pack/plugins/*/{server,public,common}/index.ts',
+        'x-pack/plugins/*/*/{server,public,common}/index.ts',
+      ],
+      rules: {
+        '@kbn/eslint/no_export_all': 'error',
+      },
+    },
   ],
 };

packages/kbn-eslint-plugin-eslint/BUILD.bazel

@@ -6,6 +6,7 @@ PKG_REQUIRE_NAME = "@kbn/eslint-plugin-eslint"
 SOURCE_FILES = glob(
   [
     "rules/**/*.js",
+    "helpers/**/*.js",
     "index.js",
     "lib.js",
   ],

packages/kbn-eslint-plugin-eslint/__fixtures__/bar.ts

@@ -0,0 +1,11 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+/* eslint-disable no-restricted-syntax */
+
+export class Bar {}

packages/kbn-eslint-plugin-eslint/__fixtures__/baz.ts

@@ -0,0 +1,13 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+/* eslint-disable no-restricted-syntax */
+
+export const one = 1;
+export const two = 2;
+export const three = 3;

packages/kbn-eslint-plugin-eslint/__fixtures__/foo.ts

@@ -0,0 +1,31 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+/* eslint-disable no-restricted-syntax */
+
+export type { Bar as ReexportedClass } from './bar';
+
+export const someConst = 'bar';
+
+// eslint-disable-next-line prefer-const
+export let someLet = 'bar';
+
+export function someFunction() {}
+
+export class SomeClass {}
+
+export interface SomeInterface {
+  prop: number;
+}
+
+export enum SomeEnum {
+  a = 'a',
+  b = 'b',
+}
+
+export type TypeAlias = string[];

packages/kbn-eslint-plugin-eslint/__fixtures__/top.ts

@@ -0,0 +1,11 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+/* eslint-disable no-restricted-syntax */
+
+export * from './foo';

packages/kbn-eslint-plugin-eslint/helpers/codegen.js

@@ -0,0 +1,82 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+const t = require('@babel/types');
+const { default: generate } = require('@babel/generator');
+
+/** @typedef {import('./export_set').ExportSet} ExportSet */
+
+/**
+ * Generate code for replacing a `export * from './path'`, ie.
+ *
+ * export type { foo } from './path'
+ * export { bar } from './path'
+
+ * @param {ExportSet} exportSet
+ * @param {string} source
+ */
+const getExportCode = (exportSet, source) => {
+  const exportedTypes = exportSet.types.size
+    ? t.exportNamedDeclaration(
+        undefined,
+        Array.from(exportSet.types).map((n) => t.exportSpecifier(t.identifier(n), t.identifier(n))),
+        t.stringLiteral(source)
+      )
+    : undefined;
+
+  if (exportedTypes) {
+    exportedTypes.exportKind = 'type';
+  }
+
+  const exportedValues = exportSet.values.size
+    ? t.exportNamedDeclaration(
+        undefined,
+        Array.from(exportSet.values).map((n) =>
+          t.exportSpecifier(t.identifier(n), t.identifier(n))
+        ),
+        t.stringLiteral(source)
+      )
+    : undefined;
+
+  return generate(t.program([exportedTypes, exportedValues].filter(Boolean))).code;
+};
+
+/**
+ * Generate code for replacing a `export * as name from './path'`, ie.
+ *
+ * import { foo, bar } from './path'
+ * export const name = { foo, bar }
+ *
+ * @param {string} nsName
+ * @param {string[]} exportNames
+ * @param {string} source
+ */
+const getExportNamedNamespaceCode = (nsName, exportNames, source) => {
+  return generate(
+    t.program([
+      t.importDeclaration(
+        exportNames.map((n) => t.importSpecifier(t.identifier(n), t.identifier(n))),
+        t.stringLiteral(source)
+      ),
+      t.exportNamedDeclaration(
+        t.variableDeclaration('const', [
+          t.variableDeclarator(
+            t.identifier(nsName),
+            t.objectExpression(
+              exportNames.map((n) =>
+                t.objectProperty(t.identifier(n), t.identifier(n), false, true)
+              )
+            )
+          ),
+        ])
+      ),
+    ])
+  ).code;
+};
+
+module.exports = { getExportCode, getExportNamedNamespaceCode };

packages/kbn-eslint-plugin-eslint/helpers/export_set.js

@@ -0,0 +1,34 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+/**
+ * Helper class to collect exports of different types, either "value" exports or "type" exports
+ */
+class ExportSet {
+  constructor() {
+    /** @type {Set<string>} */
+    this.values = new Set();
+
+    /** @type {Set<string>} */
+    this.types = new Set();
+  }
+
+  get size() {
+    return this.values.size + this.types.size;
+  }
+
+  /**
+   * @param {'value'|'type'} type
+   * @param {string} value
+   */
+  add(type, value) {
+    this[type + 's'].add(value);
+  }
+}
+
+module.exports = { ExportSet };