From 8f2aa3a2b7cd72ccb4efa1a89397f343638d1adb Mon Sep 17 00:00:00 2001
From: Philipp Spiess <hello@philippspiess.com>
Date: Wed, 7 Aug 2024 15:50:25 +0200
Subject: [PATCH] Error on invalid @plugin usage (#14134)

This PR just adds two minor errors to guard against invalid `@plugin`
usage similarly to what we do with `@source` in
https://github.com/tailwindlabs/tailwindcss/pull/14078.
---
 packages/tailwindcss/src/index.test.ts | 38 ++++++++++++++++++++++++++
 packages/tailwindcss/src/index.ts      | 10 ++++++-
 2 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/packages/tailwindcss/src/index.test.ts b/packages/tailwindcss/src/index.test.ts
index 9e1a5a8dd..70d239deb 100644
--- a/packages/tailwindcss/src/index.test.ts
+++ b/packages/tailwindcss/src/index.test.ts
@@ -1258,6 +1258,44 @@ describe('Parsing themes values from CSS', () => {
 })
 
 describe('plugins', () => {
+  test('@plugin can not have a body.', () => {
+    expect(() =>
+      compile(
+        css`
+          @plugin {
+            color: red;
+          }
+        `,
+        {
+          loadPlugin: () => {
+            return ({ addVariant }) => {
+              addVariant('hocus', '&:hover, &:focus')
+            }
+          },
+        },
+      ).build(['hocus:underline']),
+    ).toThrowErrorMatchingInlineSnapshot(`[Error: \`@plugin\` cannot have a body.]`)
+  })
+
+  test('@plugin cannot be nested.', () => {
+    expect(() =>
+      compile(
+        css`
+          div {
+            @plugin "my-plugin";
+          }
+        `,
+        {
+          loadPlugin: () => {
+            return ({ addVariant }) => {
+              addVariant('hocus', '&:hover, &:focus')
+            }
+          },
+        },
+      ).build(['hocus:underline']),
+    ).toThrowErrorMatchingInlineSnapshot(`[Error: \`@plugin\` cannot be nested.]`)
+  })
+
   test('addVariant with string selector', () => {
     let compiled = compile(
       css`
diff --git a/packages/tailwindcss/src/index.ts b/packages/tailwindcss/src/index.ts
index 73b040d4e..8b61e65b2 100644
--- a/packages/tailwindcss/src/index.ts
+++ b/packages/tailwindcss/src/index.ts
@@ -78,7 +78,15 @@ export function compile(
     if (node.kind !== 'rule') return
 
     // Collect paths from `@plugin` at-rules
-    if (node.selector.startsWith('@plugin ')) {
+    if (node.selector === '@plugin' || node.selector.startsWith('@plugin ')) {
+      if (node.nodes.length > 0) {
+        throw new Error('`@plugin` cannot have a body.')
+      }
+
+      if (parent !== null) {
+        throw new Error('`@plugin` cannot be nested.')
+      }
+
       plugins.push(loadPlugin(node.selector.slice(9, -1)))
       replaceWith([])
       return