Fix class extraction followed by ( in Slim (#17278)

This PR fixes an issue where using the class shorthand in Slim
templates, followed by an `(` results in the last class being ignored.

E.g.:

```slim
body.border-t-4.p-8(class="#{body_classes}" data-hotwire-native="#{hotwire_native_app?}" data-controller="update-time-zone")
```

This is because we will eventually extract `p-8` but it's followed by an
invalid boundary character `(`.

To solve this, we make sure to replace the `(` with a space. We already
do a similar thing when the classes are followed by an `[`.

One caveat, we _can_ have `(` in our classes, like `bg-(--my-color)`.
But in my testing this is not something that can be used in the
shorthand version.

E.g.:
```slim
div.bg-(--my-color)
```

Compiles to:
```html
<div --my-color="" class="bg-"></div>
```

So I didn't add any special handling for this. Even when trying to
escape the `(`, `-` and `)` characters, it still doesn't work. E.g.:

```slim
div.bg-\(--my-color\)
```

Compiles to:
```html
<div class="bg-">\(--my-color\)</div>
```

# Test plan

1. Added test for the issue
2. Existing tests pass
3. Verified via the extractor tool:

| Before | After |
| --- | --- |
| <img width="958" alt="image"
src="https://github.com/user-attachments/assets/f72c420e-5429-424f-a01d-12f724062bf2"
/> | <img width="958" alt="image"
src="https://github.com/user-attachments/assets/b0cc8f2f-97a8-4fca-8813-3bb1da8d99a8"
/> |

---

Fixes: #17277

Author: RobinMalfait

CHANGELOG.md

@@ -29,6 +29,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Remove redundant `line-height: initial` from Preflight ([#15212](https://github.com/tailwindlabs/tailwindcss/pull/15212))
 - Prevent segfault when loaded in a worker thread on Linux ([#17276](https://github.com/tailwindlabs/tailwindcss/pull/17276))
 - Ensure multiple `--value(…)` or `--modifier(…)` calls don't delete subsequent declarations ([#17273](https://github.com/tailwindlabs/tailwindcss/pull/17273))
+- Fix class extraction followed by `(` in Slim ([#17278](https://github.com/tailwindlabs/tailwindcss/pull/17278))
 
 ## [4.0.14] - 2025-03-13
 

crates/oxide/src/extractor/pre_processors/slim.rs

@@ -80,6 +80,23 @@ impl PreProcessor for Slim {
                     bracket_stack.push(cursor.curr);
                 }
 
+                // In slim the class name shorthand can be followed by a parenthesis. E.g.:
+                //
+                // ```slim
+                // body.border-t-4.p-8(attr=value)
+                //                    ^ Not part of the p-8 class
+                // ```
+                //
+                // This means that we need to replace all these `(` and `)` with spaces to make
+                // sure that we can extract the `p-8`.
+                //
+                // However, we also need to make sure that we keep the parens that are part of the
+                // utility class. E.g.: `bg-(--my-color)`.
+                b'(' if bracket_stack.is_empty() && !matches!(cursor.prev, b'-' | b'/') => {
+                    result[cursor.pos] = b' ';
+                    bracket_stack.push(cursor.curr);
+                }
+
                 b'(' | b'[' | b'{' => {
                     bracket_stack.push(cursor.curr);
                 }
@@ -116,7 +133,7 @@ mod tests {
                 " bg-red-500 2xl:flex bg-green-200 3xl:flex",
             ),
             // Keep dots in strings
-            (r#"div(class="px-2.5")"#, r#"div(class="px-2.5")"#),
+            (r#"div(class="px-2.5")"#, r#"div class="px-2.5")"#),
             // Replace top-level `(a-z0-9)[` with `$1 `. E.g.: `.flex[x]` -> `.flex x]`
             (".text-xl.text-red-600[", " text-xl text-red-600 "),
             // But keep important brackets:
@@ -194,6 +211,42 @@ mod tests {
         Slim::test_extract_contains(input, vec!["text-red-500", "text-3xl"]);
     }
 
+    // https://github.com/tailwindlabs/tailwindcss/issues/17277
+    #[test]
+    fn test_class_shorthand_followed_by_parens() {
+        let input = r#"
+              body.border-t-4.p-8(class="\#{body_classes}" data-hotwire-native="\#{hotwire_native_app?}" data-controller="update-time-zone")
+        "#;
+        Slim::test_extract_contains(input, vec!["border-t-4", "p-8"]);
+
+        // Additional test with CSS Variable shorthand syntax in the attribute itself because `(`
+        // and `)` are not valid in the class shorthand version.
+        //
+        // Also included an arbitrary value including `(` and `)` to make sure that we don't
+        // accidentally remove those either.
+        let input = r#"
+              body.p-8(class="bg-(--my-color) bg-(--my-color)/(--my-opacity) bg-[url(https://example.com)]")
+        "#;
+        Slim::test_extract_contains(
+            input,
+            vec![
+                "p-8",
+                "bg-(--my-color)",
+                "bg-(--my-color)/(--my-opacity)",
+                "bg-[url(https://example.com)]",
+            ],
+        );
+
+        // Top-level class shorthand with parens
+        let input = r#"
+            div class="bg-(--my-color) bg-(--my-color)/(--my-opacity)"
+        "#;
+        Slim::test_extract_contains(
+            input,
+            vec!["bg-(--my-color)", "bg-(--my-color)/(--my-opacity)"],
+        );
+    }
+
     #[test]
     fn test_strings_only_occur_when_nested() {
         let input = r#"