Fix parsing body-less at-rule without terminating semicolon (#13978)

* ensure body-less at-rules without semicolon are parsed correctly

* update changelog

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - Discard invalid classes such as `bg-red-[#000]` ([#13970](https://github.com/tailwindlabs/tailwindcss/pull/13970))
+- Fix parsing body-less at-rule without terminating semicolon ([#13978](https://github.com/tailwindlabs/tailwindcss/pull/13978))
 
 ## [4.0.0-alpha.17] - 2024-07-04
 

packages/tailwindcss/src/css-parser.test.ts

@@ -633,6 +633,14 @@ describe.each(['Unix', 'Windows'])('Line endings: %s', (lineEndings) => {
       ).toEqual([{ kind: 'rule', selector: '@charset "UTF-8"', nodes: [] }])
     })
 
+    it('should parse an at-rule without a block or semicolon', () => {
+      expect(
+        parse(`
+          @tailwind utilities
+        `),
+      ).toEqual([{ kind: 'rule', selector: '@tailwind utilities', nodes: [] }])
+    })
+
     it("should parse an at-rule without a block or semicolon when it's the last rule in a block", () => {
       expect(
         parse(`

packages/tailwindcss/src/css-parser.ts

@@ -461,6 +461,13 @@ export function parse(input: string) {
     }
   }
 
+  // If we have a leftover `buffer` that happens to start with an `@` then it
+  // means that we have an at-rule that is not terminated with a semicolon at
+  // the end of the input.
+  if (buffer[0] === '@') {
+    ast.push(rule(buffer.trim(), []))
+  }
+
   // When we are done parsing then everything should be balanced. If we still
   // have a leftover `parent`, then it means that we have an unterminated block.
   if (closingBracketStack.length > 0 && parent) {