Don't extract links as arbitrary properties

Author: philipp-spiess

CHANGELOG.md

@@ -24,6 +24,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Treat starting single quote as verbatim text in Slim ([#17085](https://github.com/tailwindlabs/tailwindcss/pull/17085))
 - Ensure `.node` and `.wasm` files are not scanned for utilities ([#17123](https://github.com/tailwindlabs/tailwindcss/pull/17123))
 - Improve performance when scanning `JSON` files ([#17125](https://github.com/tailwindlabs/tailwindcss/pull/17125))
+- Don't create invalid CSS when encountering a link wrapped in square brackets ([#17129](https://github.com/tailwindlabs/tailwindcss/pull/17129))
 
 ## [4.0.12] - 2025-03-07
 

crates/oxide/src/extractor/arbitrary_property_machine.rs

@@ -163,6 +163,7 @@ impl Machine for ArbitraryPropertyMachine<ParsingValueState> {
  #[inline]
  fn next(&mut self, cursor: &mut cursor::Cursor<'_>) -> MachineState {
  let len = cursor.input.len();
+ let start_of_value = cursor.pos;
  while cursor.pos < len {
  match cursor.curr.into() {
  Class::Escape => match cursor.next.into() {
@@ -222,6 +223,9 @@ impl Machine for ArbitraryPropertyMachine<ParsingValueState> {
  // Any kind of whitespace is not allowed
  Class::Whitespace => return self.restart(),
 
+ // URLs are not allowed
+ Class::Slash if start_of_value == cursor.pos => return self.restart(),
+
  // Everything else is valid
  _ => cursor.advance(),
  };
@@ -278,6 +282,9 @@ enum Class {
  #[bytes(b':')]
  Colon,
 
+ #[bytes(b'/')]
+ Slash,
+
  #[bytes(b' ', b'\t', b'\n', b'\r', b'\x0C')]
  Whitespace,
 
@@ -341,6 +348,9 @@ mod tests {
  ("[:red]", vec![]),
  // Empty brackets are not allowed
  ("[]", vec![]),
+ // URLs
+ ("[http://example.com]", vec![]),
+ ("[https://example.com]", vec![]),
  // Missing colon in more complex example
  (r#"[CssClass("gap-y-4")]"#, vec![]),
  // Brackets must be balanced