From 6ad3945fe7d572227289c18b0c53add63b5ed415 Mon Sep 17 00:00:00 2001
From: Jordan Pittman <jordan@cryptica.me>
Date: Mon, 9 Jan 2023 11:14:16 -0500
Subject: [PATCH] Escape group names in selectors (#10276)

* Handle escaped selector characters in parseVariantFormatString

* Escape group names in selectors

Otherwise special characters would break O_O

* Update changelog
---
 CHANGELOG.md                 |  1 +
 src/corePlugins.js           |  8 +++--
 src/lib/setupContextUtils.js | 60 +++++++++++++++++++++++-------------
 tests/basic-usage.test.js    | 24 +++++++++++++++
 4 files changed, 70 insertions(+), 23 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8fce71eae9f8..fd1a71587b35 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -34,6 +34,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Don't prefix classes in arbitrary variants ([#10214](https://github.com/tailwindlabs/tailwindcss/pull/10214))
 - Fix perf regression when checking for changed content ([#10234](https://github.com/tailwindlabs/tailwindcss/pull/10234))
 - Fix missing `blocklist` member in the `Config` type ([#10239](https://github.com/tailwindlabs/tailwindcss/pull/10239))
+- Escape group names in selectors ([#10276](https://github.com/tailwindlabs/tailwindcss/pull/10276))
 
 ### Changed
 
diff --git a/src/corePlugins.js b/src/corePlugins.js
index f92767e24cbe..47521e5eed10 100644
--- a/src/corePlugins.js
+++ b/src/corePlugins.js
@@ -150,9 +150,13 @@ export let variantPlugins = {
 
     let variants = {
       group: (_, { modifier }) =>
-        modifier ? [`:merge(.group\\/${modifier})`, ' &'] : [`:merge(.group)`, ' &'],
+        modifier
+          ? [`:merge(.group\\/${escapeClassName(modifier)})`, ' &']
+          : [`:merge(.group)`, ' &'],
       peer: (_, { modifier }) =>
-        modifier ? [`:merge(.peer\\/${modifier})`, ' ~ &'] : [`:merge(.peer)`, ' ~ &'],
+        modifier
+          ? [`:merge(.peer\\/${escapeClassName(modifier)})`, ' ~ &']
+          : [`:merge(.peer)`, ' ~ &'],
     }
 
     for (let [name, fn] of Object.entries(variants)) {
diff --git a/src/lib/setupContextUtils.js b/src/lib/setupContextUtils.js
index 2bb9350d77ce..445fceb23a57 100644
--- a/src/lib/setupContextUtils.js
+++ b/src/lib/setupContextUtils.js
@@ -54,32 +54,50 @@ function normalizeOptionTypes({ type = 'any', ...options }) {
 }
 
 function parseVariantFormatString(input) {
-  if (input.includes('{')) {
-    if (!isBalanced(input)) throw new Error(`Your { and } are unbalanced.`)
-
-    return input
-      .split(/{(.*)}/gim)
-      .flatMap((line) => parseVariantFormatString(line))
-      .filter(Boolean)
-  }
-
-  return [input.trim()]
-}
-
-function isBalanced(input) {
-  let count = 0
-
-  for (let char of input) {
-    if (char === '{') {
-      count++
+  /** @type {string[]} */
+  let parts = []
+
+  // When parsing whitespace around special characters are insignificant
+  // However, _inside_ of a variant they could be
+  // Because the selector could look like this
+  // @media { &[data-name="foo bar"] }
+  // This is why we do not skip whitespace
+
+  let current = ''
+  let depth = 0
+
+  for (let idx = 0; idx < input.length; idx++) {
+    let char = input[idx]
+
+    if (char === '\\') {
+      // Escaped characters are not special
+      current += '\\' + input[++idx]
+    } else if (char === '{') {
+      // Nested rule: start
+      ++depth
+      parts.push(current.trim())
+      current = ''
     } else if (char === '}') {
-      if (--count < 0) {
-        return false // unbalanced
+      // Nested rule: end
+      if (--depth < 0) {
+        throw new Error(`Your { and } are unbalanced.`)
       }
+
+      parts.push(current.trim())
+      current = ''
+    } else {
+      // Normal character
+      current += char
     }
   }
 
-  return count === 0
+  if (current.length > 0) {
+    parts.push(current.trim())
+  }
+
+  parts = parts.filter((part) => part !== '')
+
+  return parts
 }
 
 function insertInto(list, value, { before = [] } = {}) {
diff --git a/tests/basic-usage.test.js b/tests/basic-usage.test.js
index d310fc0e3a28..a644cbd3571c 100644
--- a/tests/basic-usage.test.js
+++ b/tests/basic-usage.test.js
@@ -689,3 +689,27 @@ it('Ring color utilities are generated when using respectDefaultRingColorOpacity
     `)
   })
 })
+
+it('should not crash when group names contain special characters', () => {
+  let config = {
+    future: { respectDefaultRingColorOpacity: true },
+    content: [
+      {
+        raw: '<div class="group/${id}"><div class="group-hover/${id}:visible"></div></div>',
+      },
+    ],
+    corePlugins: { preflight: false },
+  }
+
+  let input = css`
+    @tailwind utilities;
+  `
+
+  return run(input, config).then((result) => {
+    expect(result.css).toMatchFormattedCss(css`
+      .group\/\$\{id\}:hover .group-hover\/\$\{id\}\:visible {
+        visibility: visible;
+      }
+    `)
+  })
+})