From 44ac8c8529173711b66046ae5cfefa5bd4892461 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micha=C5=82=20Go=C5=82=C4=99biowski-Owczarek?=
 <m.goleb@gmail.com>
Date: Mon, 25 Nov 2019 20:16:53 +0100
Subject: [PATCH] Build: Require extensions for ES6 imports, prevent import
 cycles

jQuery source is now authored in ECMAScript modules. Native browser support
for them requires full file names including extensions. Rollup works even
if import paths don't specify extensions, though, so one import slipped
through without such an extension, breaking native browser import of
src/jquery.js.

A new ESLint rule using eslint-plugin-import prevents us from regressing
on that front.

Also, eslint-plugin-import's no-cycle rule is used to avoid import cycles.

Closes gh-4544
Ref gh-4541
Ref 075320149ae30a5c593c06b2fb015bdf033e0acf
---
 package.json       | 1 +
 src/.eslintrc.json | 7 +++++++
 2 files changed, 8 insertions(+)

diff --git a/package.json b/package.json
index 106417d07..1bb21b7c9 100644
--- a/package.json
+++ b/package.json
@@ -30,6 +30,7 @@
     "commitplease": "3.2.0",
     "core-js-bundle": "3.0.0",
     "eslint-config-jquery": "2.0.0",
+    "eslint-plugin-import": "2.18.2",
     "grunt": "1.0.4",
     "grunt-babel": "8.0.0",
     "grunt-cli": "1.3.2",
diff --git a/src/.eslintrc.json b/src/.eslintrc.json
index 44cb3a179..4ac59e28b 100644
--- a/src/.eslintrc.json
+++ b/src/.eslintrc.json
@@ -8,6 +8,13 @@
 		"sourceType": "module"
 	},
 
+	"plugins": [ "import" ],
+
+	"rules": {
+		"import/extensions": [ "error", "always" ],
+		"import/no-cycle": "error"
+	},
+
 	"overrides": [
 		{
 			"files": "wrapper.js",