fix(css): improve unicode wildcard range recovery

.changeset/fix-unicode-range-recovery.md

@@ -0,0 +1,22 @@
+---
+"@biomejs/biome": patch
+---
+
+Improved CSS parser recovery for invalid `unicode-range` values that mix wildcard ranges with range intervals. For example, Biome now reports clearer diagnostics for invalid syntax like:
+
+```css
+unicode-range: U+11???-2??;
+unicode-range: U+11???-;
+```
+
+with diagnostics such as:
+
+```text
+× Wildcard ranges cannot be combined with a range interval.
+  > unicode-range: U+11???-2??;
+                            ^
+
+× Expected a codepoint but instead found ';'.
+  > unicode-range: U+11???-;
+                             ^
+```

crates/biome_css_parser/src/syntax/property/unicode_range.rs

@@ -64,10 +64,24 @@ pub(crate) fn parse_unicode_range(p: &mut CssParser) -> ParsedSyntax {
     p.bump_with_context(T!["U+"], CssLexContext::UnicodeRange);
 
     // Checks if the parser is positioned to parse a Unicode range wildcard.
-    // A wildcard cannot be combined with a range interval. For example, `U+????-U+????` is invalid.
+    // A wildcard cannot be combined with a range interval. For example, `U+????-2222` is invalid.
     if is_at_unicode_range_wildcard(p) {
         parse_unicode_range_wildcard(p).ok();
 
+        if p.at(T![-]) {
+            // Wildcards cannot start a range interval (e.g. `U+????-2222`); consume the tail to recover.
+            let range = p.cur_range();
+            p.error(wildcard_range_interval_not_allowed(p, range));
+            p.bump_with_context(T![-], CssLexContext::UnicodeRange);
+
+            if parse_unicode_codepoint(p).is_absent() && parse_unicode_range_wildcard(p).is_absent()
+            {
+                p.error(expected_codepoint(p, p.cur_range()));
+            }
+
+            return Present(m.complete(p, CSS_BOGUS_UNICODE_RANGE_VALUE));
+        }
+
         return Present(m.complete(p, CSS_UNICODE_RANGE));
     }
 
@@ -173,6 +187,22 @@ pub(crate) fn wildcard_not_allowed(p: &CssParser, range: TextRange) -> ParseDiag
         )
 }
 
+/// Provides a diagnostic for invalid use of a wildcard range with an explicit interval.
+///
+/// Example: `U+11???-2222`
+pub(crate) fn wildcard_range_interval_not_allowed(
+    p: &CssParser,
+    range: TextRange,
+) -> ParseDiagnostic {
+    p.err_builder(
+        "Wildcard ranges cannot be combined with a range interval.",
+        range,
+    )
+    .with_hint(
+        "Use either a wildcard range (e.g. `U+11???`) or an explicit interval (e.g. `U+1100-2222`).",
+    )
+}
+
 /// Generates a parse diagnostic for an expected "codepoint" error message at the given range.
 pub(crate) fn expected_codepoint(p: &CssParser, range: TextRange) -> ParseDiagnostic {
     expected_node("codepoint", range, p)

crates/biome_css_parser/tests/css_test_suite/error/property/unicode_range_error.css

@@ -2,6 +2,8 @@
 	unicode-range: U+;
 	unicode-range: U+1111111111;
 	unicode-range: U+11???-2222;
+	unicode-range: U+11???-2??;
+	unicode-range: U+11???-;
 	unicode-range: U+11-2??;
 	unicode-range: U+11-;
 }